Water Quality Monitoring in Singapore's Natural Areas

A new, natural venue for water quality monitoring (WQM) - Tampines Eco Green (TEG)

2011-12-22T02:13:00.000+08:00

Invited by Nparks to help design and implement a water quality monitoring (WQM) programme, I found myself in one of their latest natural attractions – Tampines Eco Green (TEG) accessible from Sun Plaza Park along Tampines Avenue 9.

For those who are expecting fast food joints nearby, lots of parking space and plenty of lighting for an evening walk, you will be quite disappointed as there is none of the above.

Even the toilet is not the normal kind you find in other parks as it is supposedly the first of its kind in an Nparks park – an eco toilet that makes use of composting to treat your waste. It has no water for washing. Instead you press for hand sanitiser gel from that wall dispenser. No water is available for flushing. Instead, wood chips are "dumped" into the toilet bowl to help in the composting process. For those who can’t get used to such a setup for your sanitary needs, a few portable toilets are located nearby. Personally, I prefer the well ventilated eco toilet to the tightly confined space of a portable toilet with its characteristic chemical odour. (Opps, I seemed to have said too much about the toilet rather than the WQM aspects of TEG.)

But for those who enjoy a relatively natural environment for their bird watching, firefly appreciation or WQM, TEG scores very high. Formerly made up of sand quarries (and I heard it was also used as a dumping ground), TEG is now marshes and shrubs. The trail is not gravel or dirt but a comfortable carpet of turf grass.

It is outfitted with a handful of ponds of yet to be examined water quality. A few seemed to be favoured by apple snails as evident from the pink clusters of snail eggs. Some were observed with pond skaters on the water surface and dragonflies skirting the above-water vegetation. As with the water quality, the kind of aquatic life below the surface has not been surveyed.

Figure: The roughly 2-km trail surrounds several ponds of unknown water quality.

Figure: "Pond 1", nearest to the entrance, is quite muddy.

Figure: "Pond 2" is starting to show signs of algal mat formation. Is it triggered by nutrients in the water? If so, where do the nutrients come from?

Figure 3: Clear (at least in the middle and right) brownish water suggests presence of dissolved organic matter e.g. tannins in "Pond 3".

Figure: Eco toilet with composting - supposedly first of its kind in Nparks jurisdiction

Figure: Bioswales like this one are found around the trails in the park. They are supposed to clean up the water draining through the park before discharging into a nearby canal. Are they effective? No one has tested them yet.

Water quality monitoring (WQM) workshop for Sengkang Floating Wetland

2011-12-16T23:40:00.002+08:00

I have a rare opportunity to conduct a WQM workshop at Sengkang Floating Wetland which lies smack in the Punggol Reservoir. All thanks to PUB for arranging the venue and coordinating the overall workshop!

At the same time, this workshop was funded by the Water Education Fund from FairPrice which also sponsored my book - Your first guide to water quality monitoring in Singapore. Not surprisingly, all the participants were given a copy of the book to help them implement their own WQM programme.

Figure (courtesy of PUB): Classroom lesson at Anchorvale CC before heading out to the field

Figure: Getting water samples on the floating wetland was made easy with the help of contract workers who happened to be there maintaining the wetland

Figure: In the middle of the floating wetland

Figure: Participants getting their hands wet and dirty along Punggol Reservoir

Question on phytoremediation

2011-12-16T11:34:00.000+08:00

Dear Mr Kwok,

My name is C and I am a marine life enthusiast like yourself. I recently had the opportunity to visit a few fish and shrimp farms in Brunei. These farms are in land farms beside the coast. I noticed that in some of the ponds the water is obviously highly toxic with large amounts of foam floating on the surface. Owner confirms that the water in these ponds have not been changed for 1-2 months.

As each pond is approximately 10 metres by 25 metres and 2 metres deep, each farm has 40-50 ponds, it may be expensive to perform frequent water change such as those done by owners of reef aquariums.

So if there are say 20 such farms in the area, each discharging the waste water directly into the sea, wouldnt the water quality in the area be adversely affected?

The question I have for you is this:

1) In a reef aquarium, we use a protein skimmer to remove dissolved organic materials and water changes to dilute the toxic compounds in the water. This is obviously too expensive for commercial fish farming. Some hobbyists have experimented with using mangrove saplings to remove dissolved organics as a replacement for the protein skimmer. Is it possible then, to grow mangrove on floating pontoons in the fish pond? Would this be a cost effective way to improve water quality in the pond and there by improving food safety?

2) What are the issues we might have to think about if we want to plant mangrove on floating pontoons?

Thanks and regards,

C

Dear C,

You may want to read through my posts on phytoremediation

especially Singapore latest water attraction - Sengkang Floating Wetland and Before you write off a plant as a weed, read this

There are certainly many issues involved in phytoremediation via mangrove plants on floating pontoons aka floating wetlands, from conception, evaluation, design, implementation, operation to management.

I will attempt to touch on those that are close to my heart though I am sure there many other important ones which I will miss out.

1. I assume you want to use mangrove plants (I suppose you are referring to the tree types) because the water is brackish or salty. I strongly believe mangrove trees have a lot of potential to perform phytoremediation, especially removal of nutrients from pond water. However, though widely used in Asia and other tropical countries, documentation of their implementation and effectiveness are still lacking compared to other “traditional” phytoremediation plants. Certain salt marsh plants (e.g. cordgrasses, seaside rush) have been documented to be successfully used in brackish/salty water. Nevertheless, I would still encourage you to try mangrove trees since they are very much part of our natural heritage.

2. Cost! This can be a big issue if you are using any of the proprietary floating mats for holding your plants. There are many high-tech mats out in the market and they will cost you more than having a similar constructed wetland built on land. Alternatively, you can go the DIY route. I have seem floating platforms made out of bamboo, plastic bottles and other recycled materials.

3. One gripe I have with floating wetlands is their short reach with respect to the depth of the water body. You mentioned that you intend to use such floating wetlands to remove dissolved organics. Ideally, you will need a good root system well distributed laterally and vertically in the pond to achieve that. The root system allows bacteria to flourish and these are the guys on the ground removing your organics. Hence, the mangrove roots will need to go as deep as possible but a floating mat by its nature can impede the spread of the roots.

4. What about harvesting? Do you intend to remove the plants periodically? What if they grow too big for your mat to support? On the other hand, you need your plants to be big to be efficient in phytoremediation (think more biomass to absorb the nutrients or more roots with longer reach for bacteria to grow). Of course, harvesting and replanting will incur more costs.

Good luck!

Figure: a DIY floating wetland in a pond in Chinese Garden

Figure: Rhizophora sp. in Sungei Buloh Wetland Reserve - a mangrove tree that has potential in phytoremediation, especially in brackish/saline waters

Water quality monitoring (WQM) workshop for Sengkang Floating Wetland

2011-11-01T14:59:00.000+08:00

Below is a copy of the invitation sent out to MOE teachers.

Dear Educators,

We would like to invite you and your teachers to attend PUB’s Water Quality Monitoring Workshop:

Admission is free and course materials and equipments will be provided. Teachers will also receive a complimentary copy of the book,“ Your First Guide To Water Quality Monitoring in Singapore”, written by Mr Kwok Chen Ko in collaboration with PUB and the NTUC Water Education Fund.

This course is suitable for

 Science teachers, Green Club teachers and teachers interested in environmental or field work

 Teachers who are interested in conducting Water Quality Monitoring with students.

 Any teachers with a passion for the environment!

Trainer
Mr Kwok Chen Ko, Environmental Science lecturer from Singapore Polytechnic.

Course objectives

To introduce importance of water quality in the environment and how water quality monitoring can be carried out. At the end of the course, teachers will be able to:

(a) Appreciate the importance of water quality to the health of the environment.

(b) Explain how several fundamental water quality parameters interact with aquatic life.

(c) Perform field sampling of water.

(d) Perform water analyses in the field and classroom.

Topics covered

1. The types of freshwater systems in Singapore

2. What is water quality?

3. Important water quality parameters

4. The art of water sampling

5. The science of water analysis

6. How to conduct sampling, analysis and collection of water in the field.

Programme outline
The workshop consists of a classroom lecture followed by field work at the nearby Sengkang Floating Wetland.

Time Activity

1:00 PM – 1:30 PM Registration of participants

1:30 PM – 2:30 PM Lecture session:

-Introduction to Water Quality Monitoring in Singapore

- Water quality monitoring parameters

2:30 PM – 4:30 PM Practical session:

-Practical water quality testing exercise at Sengkang Floating Wetland

4:30 PM – 5:30 PM Debriefing session

Admission is limited to the first 20 participants only, so do register by 4 November 2011.

For registration please contact:

Ms Farah’ Ain Niza
Email: Farahain_Niza_Md_Tamren@pub.gov.sg
Tel no : 6731 3274

Water quality monitoring workshop for CUGE

2011-10-03T01:56:00.001+08:00

I had the opportunity to conduct an inaugural water quality monitoring (WQM) workshop for CUGE (Centre for urban greenery and ecology). The participants were mostly Nparks staff. Before this, I had only worked with MOE teachers and students in my WQM courses.

It was indeed an eye opener. With their outdoor experience, my field trip became a non-issue. No complaints about the mozzies, the mud or the weather.

In fact, I dare say this field trip to Ngee Ann Stream was my most challenging. A huge tree has fallen over the path I normally took my participants. There was no clear path through it or around it. Fortunately, a hardy participant (L) came forward to blaze a trail through the fallen tree while I was wondering whether the rest were able to handle such bashing through. Reminding myself these were Nparks staff, everyone came through without a scratch despite the big ants scrambling all over the branches in protest of our intrusion. A few other “garang” types helped to clear the trail as L and I took the lead in our trailblazing.

Because of the wet weather earlier in the day, the canal was flooded. Usually a convenient way to cover ground, the canal became out of bounds. Since these guys and ladies were as good as I thought they were, I decided to do another round of bashing through a patch of tall grasses. Since these were only grasses (not trees or shrubs), I used my handy walking stick to sweep the blockage aside. Problem solved.

Though most of the participants have no chemistry background, they were thrilled with trying out the water testing kits back in our classroom. Designed for field work and hence simple to operate, most participants took an instant familiarity with the kits’ usage. In fact, they were more than enthusiastic to stay after 5p.m. to finish their water testing with the kits. It is always a pleasure to observe students with a passion to learn and experiment.

Figure: My favourite monitoring station along Ngee Ann Stream. A good shady spot for the participants to rest after the "gruelling" hike through tall grasses and steep slopes. Notice the tall grasses in middle - we had to bash through those after this station.

Figure: This canal is normally dry with only a small flow in the centre. On this day, an earlier rain has made the canal impassable. Even the participant has to collect a water sample on the steps. Not for school students.

Figure: Using water testing kits back in the classroom

Figure: Participants putting up their water quality data for all to see and compare.

Figure: Bug hunting and identification at Chinese Garden

Figure: We had the rare chance of checking out what Chinese Garden has implemented its admirable efforts to go green. This is a phytoremediation project to treat and reuse grey water from a toilet's sinks.

Update: Here is the link for a write-up of the workshop on CUGE' website
http://www.cuge.com.sg/October-2011 > 04 Oct 2011 - A Fun and Enriching Hands-on Experience Sampling and Testing Water

New book: Your first guide to water quality monitoring in Singapore

2011-08-05T23:51:00.001+08:00

More than a year in the making, my labour finally paid off in the form of my new book "Your first guide to water quality monitoring in Singapore". Available to PUB's partner schools, schools interested in water quality monitoring and government agencies, please contact the following PUB staff for more details on getting a copy.

Ms Nora Farhain (senior officer): nora_farhain_hamim@pub.gov.sg

Figure: Front cover of the book

Figure: Back cover of the book

Excerpt from SP Website:
Mr Kwok Chen Ko from SP's School of Chemical & Life Sciences has written a book for the Public Utilities Board (PUB). Titled "Your first guide to water quality monitoring in Singapore", the book was presented at the opening of the Punggol and Serangoon Reservoirs on 3 July.

Water is fast becoming the coolest (and hottest) topic in the 21st century, as people learn more about the importance of water quality, and schools embark on various water-related projects. Chen Ko's book is a boost to the local environmental education scene, providing a no-frills guide to the basics of water quality. Designed for teachers and students in mind, it allows the readers to understand more about water quality monitoring programmes and even how to design one themselves!

As for the idea behind his book, Chen Ko said it stemmed from his vision of implementing a citizen-based approach to monitoring the waterways of Singapore, which is widely done in other countries, but had not quite taken off in ours.

"When I first started my first water quality monitoring in 2006, there was simply no guide for reference on such a topic in Singapore. I gathered whatever information I could from the Internet, books and journals and dived right into it," said Chen Ko.

After five years of water monitoring work and research, Chen Ko felt ready to impart his knowledge and experiences to a wider audience by writing this book.

Testing your drinking water - the whys and why nots

2011-08-03T23:20:00.000+08:00

I have been receiving requests to find out more about sending drinking or filtered water for lab testing - how, why, where etc. so I have compiled a short advisory here for those interested readers out there.

Some queries are linked to the use of water filters in the home e.g. filtered water actually makes the children sick. Dear readers, for goodness sake, if you think that filtered water is making your children, just disconnect the water filter and drink tap water straight or boiled. Our tap water is supposed to strictly follow WHO's drinking water guidelines.

You are strongly urged to read through my earlier posts on water filters to get a have a better background of this post.

Why?
This is probably the most important question to answer in order to justify testing your drinking water. In most cases, the user suspects that the tap or filtered water is causing health problems in the household. At this point, it will be good to be specific about your health problem and do some research to find out exactly what substance in the water can be causing that problem. E.g. gastrointestinal discomfort? Then that could be caused by bacteria in the water.

What?
Most people say that they want to send their water samples to a commercial laboratory for analysis. But analysis is a BIG word because the laboratory will then ask them, "what components in water do you want to analyse?" This is the point when most users will leave their mouths hanging. You see, there are tens of thousands of chemicals in use today and probably several different methods to analyse each of them. Even WHO's guidelines go up to more than a hundred water parameters. It is simply not economical to analyse for so many components unless you own the water utilities company. And in general, laboratory testing is not cheap - each additional parameter to test heaps on additional cost.

Ideally, you should have answered the "why" question reasonably well so that you have a good idea of what chemicals or parameters to test for. Personally, I feel that coliform or E. coli should be a good test to start with as it gives you an idea of the level of human contamination in the water. The presence of coliform or E. coli should reflect a high likelihood of other human pathogens in the water. Other potential candidates to be tested for include chlorine, fluoride, heavy metals e.g. lead, pesticides though it really depends on your particular situation.

Figure: Testing for coliforms using the membrane filtration method

Figure: Testing for coliforms using the most probable number (MPN) method

How?
There are no lack of commercial testing labs in Singapore though they serve commercial clients most of the time. Do call them up to get a quote for testing your water according to the parameters you specified. Typically, they require a water sample to be sent over to their lab. And if you want to be scientific about it, you may to perform replication in your testing i.e. testing more than 1 sample. Some of the better known testing labs are Tuv Sud PSB, SGS Testing, Setsco Services, CPG Laboratories (a newcomer).

And if you get an "ND" in your testing report, it means "not detected". It would be smart to ask the lab what kind of detection limit (DL) does their testing method involve because ND doesn't mean something is not there or means that the water is safe. ND simply means that that particular could be present but below the detection limit (BDL). Better still, ask the lab about the level of certainty of your results e.g. +- 5% or +-0.1ppm (parts per million). Professionals will normally know the answers to the above questions.

Interpretation of your test results could be the hardest part of the whole process. Most times, the lab is not qualified to interpret your results and tell you how safe your water is. You should always check against WHO's guidelines and PUB's typical values. But as mentioned in an earlier post, WHO's guidelines are not omnipotent. Therefore, you could be on your own to decide how safe your water is. In the case of water filters, the interpretation could be simplied by testing both the influent and effluent of your filter. E.g. if you filter is supposed to remove bacteria and yet more bacteria is showing up in your filtered water (effluent), suspect that your filter is failing you.

Final thoughts
I know... water testing is a big and sometimes formidable topic but I hope this post has clarified some of the points. I am always a staunch supporter of consumer education so please find out all you can about water testing, ask the right questions and hopefully make the right choice. Good luck.

Phytoremediation Question

2011-07-26T00:45:00.000+08:00

Dear Mr Kwok,

It was a pleasure to read your post on the topic "Before you write off a plant as a weed, read this...".

I enjoyed reading the article and found the information on phytoremediation both fascinating and very comprehensive.

I will like ask if there are any regulatory or monetary policies in Singapore to be considered in regards to phytoremediation applications.

I don't seem to be able to find this information and will really appreciate your sage advice.

Thank you.

Warm Regards,

J

Dear J,

Glad to know that you enjoy reading my blog article.

Incidentally, you did not mention your purpose of using phytoremediation. In it for treatment of industrial waste? Agricultural waste? Domestic waste? Rainwater harvesting? Or simply storm water filtration? Are you using it to clean water or soil or perhaps even air?

As far as I know, there are no regulations in Singapore governing the use of phytoremediation per se. However, there are likely to be regulations controlling the end result of your phytoremediation endeavour which is tied to your purpose of application. For example, if you intend to use phytoremediation to treat industrial waste before discharge into the sewers, you will have to adhere to National Environment Agency (NEA) effluent discharge limits which may or may not make phytoremediation feasible.

Public Utilities Board (PUB) does have some guidelines (Active, beautiful, clean waters design guidelines) pertaining to the design and use of water design features (e.g. bio swales, rain gardens, wetlands) to clean up storm water.

What do you mean by monetary policy? If you are referring to monetary incentives, no, I have not heard anything. The closest is PUB is quite ready to invest in pilot-scale floating wetlands in its reservoirs (Jurong Lake, Pandan Reservoir, Sengkang Floating Wetland) and a full-scale constructed wetland (Lorong Halus Wetland at Serangoon Reservoir) to try out phytoremediation.

Phytoremediation is an emerging technique in environmental pollution control. But it lacks documentation of successful applications in this part of the world. And no matter where in the world it is used, phytoremediation takes relatively long for treatment to complete and precious land is needed grow and maintain the plants that form the heart of a phytoremediation system. Money will certainly trickle into R&D in phytoremediation though I am not sure that money will be gushing into full-scale application of phytoremediation anytime soon, at least not in this part of the world.

CK

How to get rid of your seemingly unstoppable pond algae

2011-07-23T01:51:00.083+08:00

Excessive growth of algae (aka algal bloom or eutrophication) is not a new problem in Singapore. You can sometimes see a canal or even a reservoir taking on an unnatural greenish or bluish tinge. For the aquarium hobbyist, it is just as tough a nut to crack as the algae is removed physically, chemically or biologically, only to return with fresh vigour after a while, seeminlgly impossible to kill.

Figure: "Orange" algae in stream in Chinese Garden (Apr 2011)

Figure: Pond badly overgrown with "green" algae at Sungei Buloh Wetland Reserve (SBWR) (Mar 2011)

Figure: Another shot of the same pond in SBWR (Mar 2011)

With a sprinkling of scientific principles, here are my sentiments on curbing this tough guy.

First: scoping out your opponent
Find out who this tough guy really is. Algae comes in all sorts of flavours, from red, green, blue-green, brown to diatoms and dinoflagellates. To really nail it down to species level, you will need molecular techniques in well equipped labs. Since most of us do not have access to such high powered stuff, we will have to settle on visual examination under microscope. (I agree that most of us do not have a microscope stashed away at home either but at least most schools should have a few to play with.)

Figure: Microcystis spp under 10x magnification

Figure: Anabaena sp under 10x magnification

Once you have an idea of your guy, check out his characteristics. How does he grow? What are his most important nutrients? Which nutrient is the limiting one? In the case of the above 2 algae, they normally bloom in an excess of phosphorus usually in the form of phosphate.

Second: scoping out your water
Hey, this is water quality blog so yes, you have to check out your water quality. The standard parameters include: dissolved oxygen (DO), electrical conductivity (EC), turbidity, pH, alkalinity, hardness, nitrate, ammonia, phosphate, biochemical oxygen demand (BOD), chemical oxygen demand (COD). Feel free to add more if you have the resources but the above should be a good starting point. Throw in chlorophyll a (a chemical found in algae) if you think you are up to it.

Go through your water quality data. Is there anything wrong besides the algae you observe? Anything amiss could point to some systemic problem that might have triggered the algal bloom. Following the above examples of Microcystis and Anabaena, the phosphate level is likely to be elevated.

Comparative studiesUnfortunately, it is hard to define what is meant by elevated in a natural environment impacted by numerous uncontrollable factors. One way is to make comparisons. Ideally, you should compare the same variable against time i.e. what was the phosphate level 1 year, 5 years, 10 years ago. Unfortunately, almost no one in Singapore (short of PUB in their reservoirs) does regular long term water quality monitoring (WQM) of their water bodies.

The alternative is to compare against a nearby "clean" water body. Since it is algae free, does it have a lower phosphate level?

Third: scope out your environment
Assuming you have discovered elevated phosphate level in your algae infested pond, ask: where does it come from? What are the sources of water flowing into your pond? Does surface run-off carry fertilisers from your next door vegetable farm neighbour into your pond?

You may have to check historical records too as your pond may be sitting on an old farming area. If your pond sediment is choked full of phosphate from chicken waste from the previous chicken farm, you will have to get rid of the sediment.

I am all for long term solutions so learning the source of problem and tackling it at the source has always been my principle.

Fourth: ACT
As mentioned earlier, you may have the option of physical, chemical and biological methods.

Physical
Drain your pond and dredge out your sediment if it is the source of phosphate. You may also mechanically remove your algae via nets and filters

Chemical
Add alum or other chemicals (there are quite a few exotic ones in the market now) to bind the phosphate in your water into solid form and remove the solids.

Biological
By the nature of their operations (e.g. nature parks), some organisations are reluctant to use physical and chemical methods. Biological methods like phytoremediation appears appealing because of their naturalness. Yet, they may not pack the punch necessary to remove the nutrient (e.g. phosphate) sufficiently.
Other actions
Naturally, if the source of nutrient appears to come from your surroundings, you probably to get your neighbours into the picture to discuss ways to resolve your problem.

Some thoughts on "lower half of body found in Bedok Reservoir"

2011-07-01T21:49:00.000+08:00

Here is a follow-up to the article "Lower half of body found in Bedok Reservoir" in Straits Times on 21 Jun 2011 to tie up some loose ends.

No disrespect is meant by any of the comments here to the deceased and members of his family.

Being found decomposing in a reservoir, the body is bound to gather questions from the public about its effects on the reservoir's water quality and ultimately, the quality of the tap water. Since most of us live in a highly urbanised society, we tend to forget that we are still very much part of the web of life. Life and death go on continuously in the web of life, regardless of our humanly desires, emotions or concepts e.g. justice.

Chemically speaking, we are simply bundles of water, fats, proteins and minerals, similar to many animals. A reservoir, whether artificial or natural, provides for a diversity of life - an ecology unto itself. When a living thing dies in it or a human body somehow ends up in it, it will be decomposed by the same microbes and converted into the same end products e.g. carbon dioxide. (Strictly speaking though, the exact environmental conditions e.g. presence of air, determine the type of end products produced.) No, my friends, we are not so different from other living beings.

Of course, some may point out the possibility of the presence of pathogens (water borne diseases) in the waters of Bedok Reservoir due to the body. In most cases where such diseases became epidemic (floods, earthquakes), the water body has been contaminated by an overwhelming number of dead bodies or excessive dose of human waste. A single body in a normal reservoir will not likely give rise to a concentration of pathogens of concern.

Lastly, our reservoir water goes through water treatment (Bedok Waterworks) before ending up in your tap. Singapore's water treatment process is adequate to remove harmful substances, including pathogens, under normal conditions.

So drink well...

Checking out the water quality at Singapore's iconic (but mostly forgotten) landmark: Chinese Garden

2011-04-28T00:16:00.000+08:00

Some time ago, I was lamenting about the lack of water bodies in Singapore for educational activities. I now realise that I have missed out a wonderful outdoors location for my water quality studies and it is none other than our iconic Chinese Garden. (The nearby Japanese Garden and Jurong Lake Park should also fit the bill as outdoors classrooms though I have yet to check them out.) When I was younger (decades ago?), Chinese Garden was always in the spotlight for shooting of period drama serials by the then SBC (Singapore Broadcasting Corporation) (now Mediacorp). Nowadays, it is mostly forgotten except for a handful of joggers, photographers and tourists. The latest attractions in town are the sexy casino and theme park on Sentosa, as well as the panoramic sky garden and another casino at Marina Bay Sands.Chinese Garden is so "history".

What prompted me to check out Chinese Garden was a friendly meeting with the management of the Garden under JTC (Jurong Town Corporation). They are really supportive of promoting the 2 gardens and 1 park for educational purposes - outdoors lessons, water quality studies, even relevant R&D. Do approach them if you think that they fit your educational curriculum as I am sure they will oblige your request.

Enough chatter. Here are some of the findings on my trip there.

Figure: A rather commonly encountered aesthetic problem is the obvious presence of algae in a few streams and ponds. We didn't try doing any sampling for fear of allergic reactions to algae and their metabolic products.

Figure: Quite a few healthy patches of cattails. We tried sampling for bugs (macroinvertebrates) here as such densely vegetated areas are their favourite haunt.

Figure: A small water body at the dead end of a stream. Because of the lack of flow and circulation, the end of this pond is occasionally overwhelmed by suspended sediments. We also did a sampling of the bugs here.

Figure: Sorting out the bugs from our water sampling. Surprise, surprise... there are healthy populations of various bugs despite the aesthetic problems mentioned above. Lots of shrimps, damselflies, some dragonflies, quite a few mayflies, water bugs, almost no worms and no leeches. The water is biologically (and implicitly chemically and physically) healthier than most water bodies I have sampled in Singapore. Make no mistake, Chinese Garden is THE place to visit for water quality work.

Some random thoughts on floods and water quality

2011-04-18T23:47:00.002+08:00

I have been wanting to write something on floods and water quality since our Orchard Road floods make headline news in June 2010. But other committments in life came to the fore and this task became relegated to the background.

Brisbane floods: Up close (18 Jan 2011, ABC News)

Figure 1: This looks like some sort of water treatment or wastewater treatment plant in an industrial area

Figure: Same area as Figure 1 after the flood. Notice that the treatment plant is overwhelmed. If it is a water treatment plant supplying tap water, you can expect contaminants from the flood to go into tap water. If it is a wastewater treatment plant, you can expect untreated or partially treated wastewater to be carried by the flood to who knows where. Depending on the type of wastewater, contaminants can include raw sewage, industrial effluent (heavy metals, solvents etc.) or agricultural waste (animal waste, pesticides, fertilisers etc.).

Orchard Road Floods Straits Times/ Stomp (June 2010)

Figures: The same principle applies here. We had a flood. Flood washed everything around Orchard Road in its path. Let me hazard a guess - "everything" should include motor oil/ fuel (from vehicles), rubbish (glass, paper, aluminium), animal waste (stray animals, rats), pesticides/ fertilisers (lawns, green spaces) and lots of sediment (notice the "kopi susu"-like flood water). Where do you think the flood water eventually end up? Orchard Road is part of the Marina Reservoir watershed so yes, the contaminants end up in our reservoir. Our water treatment plants are supposed to be very effective so most of these stuff should be removed before reaching our taps. Even if this were true, treatment costs will likely rise from an increase in wear and tear of the treatment units handling such a heavy and diverse load of contaminants.

Figure: Tsunami caused by earthquake in Japan (Mar 2011) (japantsunamipics.com). The same can be said of a tsunami. It can carry everything nasty land pollutant in its path far inland, impacting water supplies and wastewater processing. I remember first learning about this term "tsunami" in secondary school geography. It didn't strike a chord with me then. Perhaps there weren't that many tsunamis then. But nowadays, even children know about this term when everyone can see horrific images of death and destruction following its wake. It has also receive much publicity since the tragic Asian tsunami in Dec 2004.

A disaster may be split into 2 phases with respect to its damage. The 1st phase is the disaster itself. Energy from an earthquake or flood causes loss of life and property. This phase usually lasts a short while (though there are floods that take months to recede). The second phase comes in when the population starts to rebuild their lives. The economy is torn to pieces. Food, water and fuel become scarce. Ditto for daily necessities. If law enforcement is weak and the people desperate, social disorder ensues. Without clean water (and food) and proper sanitation, people start coming down with water borne diseases which may spread without check, especially when people are herded into cramped refugee camps. See my earlier post for a fuller discussion on the aftermath of a disaster.

Answering a simple question - what is water quality?

2011-04-11T23:27:00.000+08:00

The closest things are usually the ones we miss seeing.

Having blogged for 3 years about water quality, it comes as no surprise (or does it?) that I have not talked more about what water quality is.

Let's try to define it. I am a fan of 1-sentence definitions so I shall do the same here. Water quality simply tells you whether the water is suitable for use. Simple enough? Unfortunately, real life often complicates things. For example, what use? For whom (or what)? What is meant by suitable? How to measure suitable? (There goes the 1-sentence rule...)

What use?
These come to mind - drinking, washing, bathing, cooking, swimming, recreation, industry (food & beverage, wafer fabrication, pharmaceutical, cooling water, boiler water...), agriculture (animals, crops...)... The uses of water seem endless and mind boggling. But it doesn't end here.

For whom (or what)?
Environmental science used to be human centric, focusing only on the applications for society and the effects on the human condition. With the rise of the environmental movement, care and concern for non-human entities are increasingly becoming the norm. (I must stress that humans are too part of the web of life so it makes sense to care for these non-human entities. Anything that goes wrong in the environment will ultimately comes back to impact us. Remember - everything is connected to everything else.)

Have you considered the poor fish living in the wild downstream of your wastewater treatment plant? How about that rare aquatic fern surviving precariously in an increasingly polluted river?

Environmental protection and conservation have now come into the picture. Water quality must be of an adequate standard for organisms (especially aquatic ones) to survive and thrive. As someone pointed out, good water quality is not enough to nourish the ecosystem, you need to adopt a holistic view and protect/conserve the rest of the ecosystem too.

But before we get too carried away, don't forget the mind boggling uses of water listed at the beginning. There are many perspectives to water quality. The key is to first define the use for that water. Drinking water will have rather different requirements compard to industrial and agricultural water. Water quality for human consumption can be quite different from that for a fish or frog.

Just as water quality is only one of the many components of conservation, conservation is too only one component of water quality. You may protest, "what has happened to the 'nature conservation' given in your blog profile?" Nothing has happened. I still believe in conserving nature. But realise that water quality is a big topic, encompassing many different viewpoints that sometimes do not fit in well with one another.

What is meant by suitable? How to measure suitable?
This could be a can of worms so I will try not to open it (at least not in this post). Suitability is described by the various water quality parameters (dissolved oxygen (DO), pH, turbidity, metal content, pesticide concentration and many many more). Obviously, the type of use will determine which parameters are important and the limiting values of those parameters. For example, low DO is not a big issue for human drinking except that the water may taste flat. Yet a low DO water can get a fish killed from asphyxiation. Another example - a zero coliform count is expected of drinking water yet a count of less than 200 per 100mL of water is considered all right for swimming.

"Suitability" can be a dodgy term. Yet, I believe that regardless of the inadequacies of water quality parameters and their limiting values, they at least give us a grasp on the elusive nature of water quality and hopefully allow us to work towards better ways of defining water quality.

Latest wetland craze - Lorong Halus Wetland

2011-04-07T00:00:00.001+08:00

Wetlands seem to be all the rage in Singapore right now. With the launch of Sengkang Floating Wetland in November 2010, we now have the latest wetland launched (kinda reminds me of the incessant condominium launches in Singapore now) at Lorong Halus on top of our old landfill before Pulau Semakau took over. After talking to 2 staff from CUGE (Centre for Urban Greenery and Ecology), I found that there are many more wetlands being built all over our island, being part of experiments to clean up water.

Hey, don't get me wrong, I am all for installing constructed wetlands. If designed and managed well, they are effective in improving water quality (see post on using plants to clean up water). They are also pretty to look at, especially if the wetland attracts a diverse range of wildlife. Unlike artificial concrete and steel in a wastewater treatment plant (WWTP), a constructed wetland is mostly natural which is where its greatest appeal lies. (Though constructed wetlands are supposedly cheaper than conventional WWTP, I was told that our much publicised wetlands run into price tags of six figures or more. Perhaps, most of the cost went into paying the foreign expertise for design and possibly imports e.g. floating mats to make a floating wetland.)

The best thing about Lorong Halus Wetland (LHW) is it is not just a showpiece. It actually works! It functions as a treatment unit for leachate escaping from the former landfill at Lorong Halus. Leachate from a landfill can contain all sorts of nasty contaminants like heavy metals and toxic organics which can escape into the Serangoon Reservoir and subsequently into the water treatment plant.

What does the future hold?
I personally believe that constructed wetlands (a type of phytoremediation - defined as the use of plants to clean up soil and water) will become more widespread in the near future. As society becomes more environmentally conscious (what with the issues of climate change being publicised almost non-stop nowadays), people are starting to look for sustainable and environmentally friendly methods of treating wastewater. Even though constructed wetlands have their limitations (e.g. a need for land), their natural appeal and sustainable character are hard to beat. And if you are business minded, this is one natural technology that should not be overlooked as its market (especially in developing Asia) is set to grow. I will be writing more about this in future posts.

Back to LHW

Figure 1: PUB (Public Utilities Board) seems to releasing this watershed map of Singapore in recent projects. (Read more about how to interpret a similar map in post on Sengkang Floating Wetland.) Of particular highlight is the dark blue (also blown up as a circular insert above) area which delineates the watershed for Serangoon Reservoir.

Figure 2: Compare this old watershed map from PUB to the one in Figure 1. This old map split Singapore into only 3 catchment areas - East, Central, West. I believe this is more for adminstrative purposes (certain PUB departments are also split according to these 3 regions) rather than based on geography.

Figure: The wetlands are in the upper part of the figure, consisting of reed beds (green with white dots) and polishing ponds (small patches of light blue).

Figure: As in Sengkang Floating Wetland, there are ample signboards to educate the visitor about the site. Here, it explains why a constructed wetland is needed at Lorong Halus. (Answer: to clean up the leachate escaping from the landfill.)

Figure: Another signboard explaining the need for polishing ponds after the leachate has gone through the reed beds. (Answer: the ponds are there to remove leftover nutrients and suspended particles.)

Figure: In the distance, you can see the Serangoon East Dam which closes up Serangoon Reservoir. I imagine like most local dams, it only allows water to flow out and not in from the sea, hence, keeping the reservoir water fresh and preventing seawater from intruding.

Figure: One of the reed beds consisting of Papyrus. You probably find that this layout does not fit the definition of a wetland but it does or at least, it is defined as a constructed wetland. This type is known as HSSF (horizontal sub-surface flow) where the wastewater flows in the sub-surface via the plant roots where treatment takes place.

Figure: Another reed bed, notice the gravel filling up the constructed wetland. This is advantageous because the wetland is "covered up", hence is aesthetically more acceptable - no unsightly wastewater and little offensive odours. Hey, you can even walk across the gravel bed as the gravel filling is well packed. Also the use of gravel allows the wastewater to flow underground easily through the empty spaces among gravel pieces.

Figure: A polishing pond. This design is also known as FWS (free water surface) as opposed to HSSF. By this time of the treatement process, the wastewater should be more or less cleaned since the reed beds have already done their dirty job of removing most contaminants. Therefore, an open water surface (or FWS) will be quite reasonable here.

(Update: you can find out more about how to clean up rainwater before it flows into our reservoirs in PUB's ABC (active, beautiful & clean) waters design guidelines. These guidelines advise developers and industry professionals to incorporate environment friendly features such as rain gardens, bioretention swales and wetlands in their developments.

Remember our watershed concept? Almost 70% of rainfall in Singapore lands in a watershed somewhere, ultimately ending up in our reservoirs. The plants and soil media employed in the above features act as “filters” to remove nutrients and sediments from the water going into our waterways.)

Outdoors classroom - Ngee Ann Stream

2011-03-02T23:38:00.001+08:00

It is good to be back at Ngee Ann Stream where my water quality monitoring (WQM) workshop first started. Since then, I have brought groups on field trips to many other locales but none as charming as Ngee Ann Stream - so close to civilisation yet retaining the rustic and rural character of a lost world unknown to most Singaporeans. Despite losing some of its charm to development, I have never found another field location quite like it - a combination of different freshwater habitats, chest high Buffalo Grass to bash through, water seeping in through your shoes from the soggy soils, balancing yourself on narrow ledges, climbing down algae infested steps which are really part of a drain... the list goes on. (In KCK's list, Binjai Stream is in a close fight with Ngee Ann Stream for the most interesting waterway in Singapore but Binjai is more back to nature whereas Ngee Ann is more back to kampung so their charms are rather dichotomous.)

This time round, I have the pleasure of bringing students from River Valley High to my favourite outdoors classroom. The highlight of the trip must be the sudden heavy downpour near the end, accompanied by thunderous light show, courtesy of Mother Nature. Before this, many days have passed without rain - not a good sign as this means rain and thunderstorms become more probable with each passing day. (I know, this sounds like pseudoscience but it really works!)

Being in a canal when a big storm comes is a downright lousy place to be in - open terrain with no safe shelter and subject to flash floods which is such a trendy topic in Singapore nowadays. Being young (in age, if not, at heart) and energetic, we scurried back to the safe and dry confines of our transport in one piece. In case anyone thinks that such weather makes field trips a big no-no, nothing could be more wrong. We are living in Singapore, a country in the tropics - heavy rainfall is normal, thunderstorms are normal while shivering in an air-conditioned room all day is NOT normal nor healthy. We should not be baby-proofing nature (phrase is taken from Ice Age 3) for our youth. Given our current rate of development, I hope I won't ever see Singapore entombed in a climate controlled (aka air-conditioned) dome with nature only found in manicured parks and the only waterways are covered or canalised ones.

Ok, rant mode off... here are some pics for sharing.

Figure: Our field trip itinerary includes crossing the currently operational railway track. I always wonder what would happen to this beautiful patch of railway land when it is returned to Singapore. Will Ngee Ann Stream be further developed?

Figure: WQM in the canal. Most people don't get to climb into these canals throughout their lives.

Figure: In my opinion, the best photo of the day. Heavy downpour, wet staff and students, umbrellas out if available, a sense of urgency to scramble out from the canal - something real-life, capturing the moment and not posed

Figure: Posed photo - using a colour comparator to measure the ammonia content in the water back in the indoors classroom

Evaluating the necessity and usefulness of water filters for domestic tap water

2011-02-12T12:32:00.001+08:00

My above project has finally concluded after months of experimental work by my project team.

Due to the popularity of water filters in the market these past years, I thought it will be interesting to find out more about them, especially if they are necessary and useful.

Filter 1

Figure: Home-made gravity filter using Doulton Supersterasyl filter candle (the white thingy in the middle) - ceramic (diatomaceous earth) filter impregnated with silver and incorporating a granular carbon core

Filter 2

Figure: Pressure filter train utilising standard 10-in filter housing. Order of filtration from input to output: pleated 5-um, twisted yarn 1-um, granular activated carbon (GAC), ion-exchange, fluoride reduction, pleated 0.5-um, pleated 0.35-um

Tap water was sampled from 4 different tertiary institutions well distributed spatially in Singapore. It was then allowed to run through the 2 types of filters. The raw tap water, filtered water from filter 1 and filtered water from filter 2 were tested for the following parameters - turbidity, pH, conductivity, nitrate, fluoride, total hardness, chloride, sulphate, phosphate, iron, manganese, copper, aluminium, total chlorine, aerobic bacteria count, lead. Most of the above parameters are similar to the routine testing done by PUB.

Figure: Portable water quality with typical PUB values and WHO guidelines

Tap Water Results
From the above table, you may have noticed that most of the PUB's values are well below the limits under WHO guidelines. Well folks, good news! Most of our results lie within PUB's values so PUB is not kidding in providing quality tap water. (However, WHO guidelines are not omnipotent as you may have read in my previous post - water filters in Singapore.)

For the astute reader, you may have noticed the word "most". For 2 institutions, copper content in tap water is at 0.21mg/L and 0.15mg/L, respectively - much higher than the PUB value of 0.05mg/L. In case you start jumping to the wrong conclusion, don't forget that the values above only apply to water coming of PUB's waterworks. The water still has to travel through miles of piping through the distribution network and store at various locations along the way before ending up at your tap. Lots of things can go wrong - leaking lines, corroded piping, poorly maintained tanks etc. Older buildings probably have corroding copper pipes which jack up the copper content in tap water.

The other parameter of interest is fluoride. Surprisingly, 2 of the institutions have tap water containing only 0.1mg/L fluoride while the other 2 just meet the minimum of 0.4mg/L as given by PUB. Officially, fluoride is added (yes, it is not a contaminant but is intentionally added) into water to fight tooth decay. Are we getting enough fluoride in our water for it to do its job? On the other side of the story, critics have fought against fluoridation at any level as we are already getting enough fluoride in our diet and taking in more can compromise our health - see fluorosis.

The next big thing in water is chlorine. Relax... our water is not overchlorinated. Instead, the tap water results are in the range of 0.05 - 0.15mg/L. Different sources cite different values for adequate chlorination at the end user, ranging from 0.2 - 0.5mg/L or even more. Our results are rather low so the question is whether our tap water is adequately disinfected. As you would have guessed, there is another side of the story - consuming chlorinated water has been linked to several cancers and heart disease. It is also inked to the production of trihalomethanes (THM) and haloacetic acids (HAA) in water, both of which are likely carcinogens. Hence, a low level of chlorine in tap water may actually be good news.

2 institutions have very high levels of bacteria but don't be alarmed. We are measuring aerobic bacteria and not an indicator bacteria like faecal coliform or Enterococcus. Of course, the older the distribution network and the poorer maintained it is, you are likely to see more bugs in your tap water. Actually, the purpose of measuring aerobic bacteria is to gauge the effectiveness of filtration by comparing the values before and after filtration.

Filtration Results
Frankly, because our tap water is so clean, the filters we tested could not perform as well as they could have or were certified for. Certification e.g. NSF/ANSI standard 42 or 53 requires a certain challenge inflow concentration. If the outflow concentration falls by a certain percentage, say 90%, the device has passed the test. But if the inflow concentration is already very low, a 90% reduction is not likely to be achieved.

The gravity filter appears significantly more capable at removing chlorine (25%), iron (92%), manganese (34%) and aluminium (55%) while the pressure filter seems better at reducing nitrate (42%), fluoride (58%), hardness (35%), chloride (40%), copper (75%) and bacteria (> 94%).

However, sulphate does not appear to be significantly reduced by either filter (< 7%).

Final thoughts
Are water filters necessary?

If you trust WHO guidelines and PUB seems to be doing a good job at providing quality water consistently, then no, you probably don't need them.

But if you feel that for whatever reason, WHO guidelines (or PUB typical values) are not adequate at safeguarding your health, by all means get a filter but know that to reduce the contaminant level even further, a filter probably won't cut it. You probably will need reverse osmosis, distillation or air-to-water units to give you the next level of water purity. In any case, it is good to be sure of exactly what you are concerned about e.g. chlorine, fluoride. Better still, send samples of your tap water to a commercial lab for analysis of that particular concern. AND submit for analysis another sample after going through your preferred treatment. You should then be able to have a good idea if your treatment unit is working up to your expectations.

Of course, you may suspect that there is something wrong with the distribution network. My advice is the same - be clear of your concern, analyse your water and get a treatment unit only if necessary, preferrably with a follow-up analysis of your treated water.

Water quality monitoring course coming up: 1 Jun 2011

2011-02-11T17:18:00.001+08:00

The next run of my water quality monitoring (WQM) course will be held on 1 Jun 2011. Formerly only offered to MOE teachers and staff, it is now open to members of the public too. (This came about because of the various requests from non-MOE staff and nature lovers who want to participate in the course as well.)

WQM involves checking the health of waterways on a regular basis. Whether in natural streams or urban canals, most of the water ends up in our reservoirs which provide our drinking water. Hence, WQM plays a vital role in safeguarding our water supplies.

If you are interested, you can find out more about the fascinating world of WQM in this course. Teachers and MOE staff, as well as members of the public can sign up here. For more details on the course, click

Course title: My forest is DYING and the role of water quality

Date: 1 June 2011
Time: 0900 - 1700
Venue: Singapore Polytechnic and field location
No. of participants: 20

More details can be found here. Write-up of previous runs may be found here - 1, 2. (My other WQM courses for students can be found here - 1, 2)

The things that nobody told you about Pasir Ris

2011-01-31T22:23:00.012+08:00

The water quality off Pasir Ris Park has piqued my interest since it has been in the limelight for failing the Enterococcus test for primary contact activities (e.g. swimming) for 3 years in a row (2008 - 2010) and the mass fish kill in Dec 09/ Jan 10 (see previous posts). I also found out that further back in Dec 06/ Jan 07 (1, 2, 3), another mass die-off has been observed and the reason was suggested to be a sharp drop in salinity (Update: In her blog, Ria Tan questioned whether Chek Jawa will survive the incessant rain in Jan 2011). Therefore in 2010, I decided to get my team to test out the water quality off Pasir Ris at 2 patches of seagrasses - 1 close to Sg Loyang and the other close to Sg Tampines.

Figure: Patch of seagrass near Sg Loyang

Figure: Another patch of seagrasses near Sg Tampines

Fast forward to the present, and we have some interesting results to share, not just on Pasir Ris but also on the other 2 locations we monitored. Evidently, Enterococcus is not the only thing we have to worry about.

Data were obtained from sampling seawater and sediments in three selected seagrass areas, namely Chek Jawa (CJ), Pasir Ris (PR) Park and Pulau Semakau (PS) from June to December 2010. Sampling dates and times corresponded to tide levels of 0 to 0.5m for safety reasons and ease of seagrass observation. Our team made 6 visits to Chek Jawa (2 sites), 6 visits to Pasir Ris Park (2 sites) and 2 visits to Pulau Semakau (3 sites) during the monitoring period. (The smaller number of trips to Pulau Semakau was due to logistical constraints hence the team could only head there together with Team Seagrass on their routine seagrass monitoring sessions.)

Our on-site tests include air temperature, water temperature, pH, dissolved oxygen (DO), electrical conductivity (EC), turbidity and nutrients in water - ammonia (NH3), nitrate (NO3-) and phosphate (PO43-). Laboratory testing of water samples involves Escherichia coli (E. coli), chemical oxygen demand (COD), total alkalinity, total hardness, calcium and magnesium hardness, metal ions (aluminium, copper, iron and lead) and chlorophyll a. Sediment samples were also brought back to the laboratory to analyse for nutrient content - ammonia (NH3), nitrate (NO3-) and phosphate (PO43-).

Summary of results

The values below were obtained by averaging all the results for each location. For ease of reading, only the notable water quality parameters are highlighted.

* ND = not detected

DO (mg/L) 10.5 (CJ), 8.79 (PS), 5.85 (PR)
DO is significantly lower at Pasir Ris. While considered acceptable compared to waters elsewhere in Singapore, these DO levels were relatively low for a seagrass area which is supposed to photosynthesise and produce oxygen in the day.

EC (mS/cm) 43.9 (CJ), 46.0 (PS), 42.7 (PR)
The average EC appeared consistently healthy for all 3 areas except for Chek Jawa in November 2010 for which the EC plummeted to 24.67 mS/cm at site 2.

Turbidity (NTU) 30.6 (CJ), 18.9 (PS), 262 (PR)
The water at Pasir Ris is significantly more turbid. Turbidity measures the loss in transparency in water due to the presence of suspended particles such as phytoplankton and silt. Fishes start to experience stress when exposed to a turbidity of 10-100 NTU for several hours.

E. coli (CFU/ml) 17.3 (CJ), 2.17 (PS), 23.4 (PR)
Though E. coli is a different bacterium from Enteroccus, it too indicates the presence of faecal contamination, just like Enteroccus.

Pasir Ris and Chek Jawa are significantly higher in E. coli count compared to Pulau Semakau.

E. coli has the highest count at 76 CFU (colony forming unit)/mL in November for Pasir Ris site 2. United States Environmental Protection Agency (USEPA) standards provide a maximum of 10 CFU/mL faecal coliforms for primary contact activities e.g. swimming, and a maximum of 50 CFU/mL for secondary contact activities e.g. boating.

COD (mg/L) 135 (CJ), 136 (PS), 132 (PR)
Surprisingly, the organic matter content in all 3 areas was rather similar and compares well with values obtained in our coastal areas in 2009.

Iron (mg/L) 0.998 (CJ), 0.314 (PS), 1.34 (PR)
Though not considered a threat to marine life, Pasir Ris has the highest iron concentration.

Aluminium (mg/L) 0.612 (CJ), 0.0148 (PS), 1.64 (PR)
Pasir Ris has significantly higher concentration of aluminium. The toxicity of aluminium depends to a large extent on the water pH, with the most toxic aluminium compound forming at pH 5.2-5.8. At pH 7.0, a concentration as low as 0.52 mg/L was found to reduce the growth of rainbow trout. In another example, a mass kill of maraena and peled fry occurred at 0.3 mg/L at a pH of 7.0-7.5. Seawater contains an average of 0.01 mg/L aluminium.

Lead (mg/L) 0.181 (CJ), 0.0428 (PS), ND* (PR)
Superb! Pasir Ris water has no lead detected!

Chlorophyll a (µg/L) No data (CJ), No data (PS), 7.59 (PR)
Though not shown in the averaged result above, chlorophyll a concentrations peaked at 25.1 µg/L at site 2 and 19.2 µg/L at site 1 for Pasir Ris in December. This placed the water within eutrophic condition as given under the guidelines for USA (10-500 µg/L). Eutrophic water has excessive nutrients which support an abundance of algae releasing chlorophyll a.

Nutrient in Water

Ammonia (mg/L-N) 0.174 (CJ), 0.178 (PS), 0.345 (PR)
Pasir Ris has significantly higher concentration of ammonia. Ammonia is toxic by itself. It can also contribute to eutrophication.

Nitrate (mg/L-N) 0.103 (CJ), 0.0875 (PS), 0.242 (PR)
Pasir Ris has significantly higher concentration of nitrate. Nitrate can contribute to eutrophication. Concentrations of 0.1-0.75 mg/L nitrate + ammonia N in fresh waters or even less in saline waters have been enough for a bloom.

Phosphate (mg/L-P) ND* (CJ), ND* (PS), 0.103 (PR)
Pasir Ris has significantly higher concentration of phosphate-phosphorus. Like nitrogen, phosphorus can contribute to eutrophication. A level of 0.005-0.5 mg/L P is already enough to cause phytoplankton blooms.

I have tonnes of water at my door but none in my pantry - Queensland floods

2011-01-14T22:18:00.140+08:00

If you have been reading into floods, earthquakes and other disasters, you should have guessed that the scene portrayed in the following figure is "normal". In fact, this photo immediately caught my attention, prompting me to write this post.

100,000 to lose power, supermarkets bare as flooding crisis continues (11 Jan 2011)

Figure: Actually, the amazing thing about this scene is there ARE still bottles of water on the shelf. I imagine the photographer positioning himself capture the shot in the midst of hordes scrambling to grab water, food, batteries, flashlights, fuel, candles, first aid items and toilet paper (TP) (yes, TP is incredibly valuable in an emergency though few people talk about stocking it up) in the supermarket.

Regardless of the country (developed e.g. Australia, developing e.g. Haiti, communist) and the type of disaster or emergency (flood, earthquake, civil disobedience, war), the same patterns are often observed.

The chain of event goes something like this (also see this earlier post on the earthquake in Chile based on similar themes):

Dysfunctional utitlitiesElectricity usually goes down. This has wide ranging implications as many other services depend on this modern convenience. And in the case of floods, the power company may turn it off to prevent accidental electrocution. Same goes for gas lines during an earthquake, the gas company turn them off to prevent explosions due to gas leakage.

Water supply may or may not be disrupted. Even if your tap continues to run, the water may not as clean as before due to contamination at broken lines or inadequate treatment at the water works.

Though fixed line phones are not directly tied to the electrical supply (i.e. your phone may still work even if your power is down), the physical cables and switches may still be affected by the disaster. In case you think your cellular phone has a better chance, don't count on it as the disaster can strike at the wireless transceivers placed around you. (Next time when you are outside, watch out for those usually grey boxes with 2 antennae hanging above you e.g. lamp post. There, you have your cellular transceiver.)

Sanitation - big and ugly problem. What are you going to do if your WC stops working. Do you have a chemical toilet tucked away somewhere? Not likely. This is a very real problem yet few people want to come face-to-face with it (same as for TP).

Not really counted as a utility but highly valuable and useful - money. Due to a lack of power or communications, forget about using your credit card or debit card. Even cheques are viewed with suspicion. (Is your bank still going to operate after the flood/earthquake/emergency?) Cash is KING. And it pays to have small change and denominations for the small value items. By the way, your ATM is probably not working or out of cash.
The mad rushPeople may initially be in a state of denial about the extent of damage. (Right, the government will fix things up. Or we can depend on the utilities companies to bring everything back to life within hours.) Once they wake up to the fact that our modern conveniences are not going to be back for some time, panic rushes in. Supermakets are raided for food, water.... Even items of dubious value (e.g. caviar) are cleaned up with all the cash one can master. If you are heading to the supermarket at the same time when the hordes are on a spree of panic buying, good luck.
Civil disorderDepending on how strong the authorities are and how fast they can deploy policemen and soldiers, civil order may break down. (Remember, policemen and soldiers may also be affected by the disaster so whether they turn up for work is a big question.) When people go hungry and thirsty and uncomfortable (or worse still, their children are experiencing these problems), morality, legality and decency can go the way of the window. Riots, looting, burglary, kidnapping and daylight robbery crawl out of the woodwork. I added kidnapping because I have read of criminals kidnapping children in exchange for food and essential items from the parents during Hurricane Katrina.
Health issuesIf normalcy is not restored soon (say days or weeks), the lack of clean water and food and adequate waste disposal (both liquid and solid) will take a toll on the population's health. Water borne diseases like cholera and typhoid are incredibly easy to spread among people packed together in refugee camps having less than proper sanitation. Dead bodies of humans and animals may lie (or float) in the streets waiting to be cleared. Add in malnourishment and you have the recipe for diarrhea and dysentry in addition to the big 2 above. Children and the elderly normally suffer the most. In the tropics, you can also count on vector borne diseases like dengue rearing its ugly head.

I am sure I can continue writing on and on but the idea is disasters suck. And they suck worst when you do not know of its consequences and/or are unprepared for them. (Yes, I have not written anything about the preparation part but that would be too much for a single post, right.)

Singapore latest water attraction - Sengkang Floating Wetland

2011-01-04T22:58:00.003+08:00

I finally had the chance to visit this latest water attraction in Singapore. It is not in Sentosa but right in the middle of Punggol Reservoir surrounded by Sengkang, Anchorvale and Punggol housing estates. Publicised since at least 2007, the Sengkang Floating Wetland was finally launched in Nov 2010 by PUB (Public Utilities Board). See PUB press release 07 Nov 2010: Wet and Wild

Figure: PUB poster on "Sengkang Floating Island" (circa 2007)

Figure: A map showing the floating wetland (in green) in the middle of Punggol Reservoir with Anchorvale Community Club in the east and Sengkang Riverside Park in the west

What I found highly useful are the numerous signboards describing the wetland, how it works, the importance of the watershed (covering Punggol, Anchorvale and Sengkang) and the various water plants grown on the wetland itself.

Figure: This is probably the best take-home message from the signboards. It actually shows the delineation of the watersheds (light blue)for all 17 reservoirs (dark blue) in Singapore. Of particular interest are the white areas which represent non-watershed areas i.e. rainwater falling in these areas do not go into any reservoir. A good guess would be about 70% of Singapore's land area is used to collect rainwater. Another interesting point is Changi Airport area is NOT a watershed though the airport itself harvest rainwater for its own water demands. See previous post - How to reduce flooding in Singapore? Harvest more rainwater!

Now, a floating wetland is a kind of constructed wetland but unlike the traditional constructed wetland, it floats on the surface of a water body rather than acts as a container for the water body. Flotation is achieved using a mat of polymeric material which acts as a substrate for water plants to grow and at the same allows the roots to penetrate into the water column. PUB already has several of these floating wetlands (in a smaller scale) in other reservoirs - Lower Seletar, Pandan.
(Update: Sengkang Wetland is based on BioHaven floating islands which have been used in other countries.)

Figure: A mini floating wetland at Pandan Reservoir

Figure: A conventional constructed wetland in Mississippi (http://coastal.msstate.edu/cwres.html)

Constructed (and floating) wetlands are usually designed to clean up the water, improving water quality. The roots and the underside of the polymeric mat tend to accumulate a layer of biofilm containing bacteria, fungi and algae which help in the decomposition of organic matter, nitrogen (e.g. ammonia) and phosphorus compounds. The water plants themselves also can absorb nitrogen and phosphorus, as well as certain heavy metals. Their roots extend into the water column not just for aesthetics but they can also filter and trap sediments. Such a use of plants to clean up the environment is known as phytoremediation. For a more complete discussion, check out this post - Before you write off a plant as a weed, read this

Besides the benefits of cleaning up water and providing a refuge for wildlife, a floating wetland has several advantages over a conventional constructed wetland. It is easily fabricated elsewhere and several units can be joined together to make a large wetland in actual deployment. It can be conveniently placed in existing water bodies without excavation and retrofitting of the existing landscape. If you find lake X has poor water quality, just push a few floating units into the lake. And when they have accomplished their tasks or if problems crop up, they can be conveniently removed as if they were never there in the first place.

However, a key design of constructed is the depth and width of the water body. For the plants (and associated biofilm) to work their magic, the water has to pass through the zone of influence of the roots. A lone floating wetland in the middle of a wide and deep river is not likely to have enough juice to clean up the river. I am not sure how deep the Punggol Reservoir is but if it is like most reservoirs, probably a few metres deep. I doubt the roots can reach to such depths. Also, when I look at the map of the Sengkang Floating
Wetland (see above), it appears exactly like a lonesome patch of greenery surrounded by a swath of blue. Can it really improve the water quality? If yes, how much? (As a side note, I may be conducting water quality monitoring workshops here so perhaps, the water quality data can provide a better picture.)

Anyway, water cleaning efficiency aside, Sengkang Floating Wetland is an excellent showcase of Singapore's focus on active, beautiful and clean water.

Figure: A boardwalk connects the floating wetland to the 2 banks and allows visitors to get up close and personal.

Figure: Viewing the floating wetland and boardwalk from Anchorvale CC. Notice Sengkang flats in the distance

Australia inundated by flooding

2011-01-03T20:15:00.001+08:00

We seem to be seeing more flooding and at more serious intensities around the world these years. From New Orleans to Malaysia, Pakistan and now Australia, floods have had a busy decade. While some fingers point to climate change, others point to El Nino/ La Nina effects and still others decry the destruction of natural buffers such as wetlands and coral reefs as the culprit to widespread flooding.

The latest flood on the block:
Australia floods larger than France strand 200,000

"The muddy water inundating thousands of homes and businesses has led to a shortage of drinking water and raised fears of mosquito-borne disease...

The town was facing food shortages, power outages and sewage-contaminated floodwaters..."

And like all floods (and most natural disasters e.g. earthquake in Haiti, Chile), the victims are facing a shortage of clean drinking water, lack of sanitation services, contamination from wastewater (sewage) and water (and vector) borne diseases in addition to all the other inconveniences such as power outages, shortage of food and lack of shelter.

Singapore wastewater reuse

2010-12-22T01:03:00.000+08:00

Dear Sir,

I am currently looking for information regarding wastewater reusing in Singapore.

Basically, I am looking for the Singaporean regulatory framework as far as reuse of wastewater is concerned, to answer this very specific question : which recycled water quality for which use (agricultural, domestic, urban uses…) ?

I have found your blog very interesting and I wonder if you could help me to find the information I need or to advice me where I could find it.

This would be extremely helpful.

I really thank you for your diligence.

Yours sincerely,
N

Dear N,

As mentioned in an earlier post, Singapore is a small country so almost all its water needs and wastewater (domestic) handling services are provided by a single government agency, PUB (Public Utilities Board). Again, due to the country's size, reuse of domestic wastewater is limited to the production of NEWater and industrial water by none other than PUB. NEWater is a highly purified water suitable for high-end electronics manufacturing (and drinking of course) but also used to supplement our reservoir water. Industrial water is non-potable and only used by chemical industries in Jurong Island.

The water quality of NEWater is partially given here (I am sure many more other tests on NEWater have been performed though their results are not publicised). Water quality for industrial water is even harder to find. You probably have to approach PUB for more answers.

Good luck.

Water filters in Singapore

2010-12-21T20:13:00.002+08:00

Dear Mr Kwok,

I happened to read your blog http://waterqualityinsingapore.blogspot.com/ and I was wondering if you could help me with my project, "Study on the Effect of Poorly Maintained Water Filters on Water Quality". You mentioned that you did a project on the effectiveness of water filters, could you share the research paper/report with me? I will definitely acknowledge the source under my report so not to worry.

I have a few questions to ask as well:
1. Do you have any opinions/comments/inputs with regards to my project title?
2. Why would people still buy water filters although our tap water is well within WHO standards?
3. What is the major cause why these tend to be poorly maintained (because they forget to change, it is costly to change, do not know they have to change[perhaps the people who sell the filters to them did not mention it explicitly], etc?)
4. What kind of water filters are being sold in Singapore and which are the ones that are more likely to be poorly maintained?

I would certainly very much appreciate it if you could help me out.

Thank you very much!
Best regards,
R

Hi R,

More information about water filters may be found in my earlier posts.
My project on testing the effectiveness of water filters is still on-going so I am not able to share the results with you at the moment. If all goes well, it should finish by Feb 2011 and I will post the results on this blog.

Your project will certainly be useful and of interest to consumers of water filters as this is a poorly researched topic with even less publicity on the results from the few studies on said topic.

I suppose that your project pertains to the Singapore context which is rather unique compared to most parts of the world. Becuase of our small size, water supply is controlled, regulated and provided by a single agency, PUB (with the exception of some islands). In this aspect, I believe that PUB has done a good job of providing safe and affordable drinking water to the populace. In Singapore, you don't see epidemics of water borne diseases or people suffering from dehydration. This of course presents a unique market for water filters. People are not worried about pathogens like Giardia, Cryptosporidium or Salmonella in their tap water. (Despite this fact, most people still boil their water here.)

As you ask, why are people buying water even though our tap water is well within WHO standards? I am afraid you will have to conduct a consumer survey to find the real answer(s) but I shall offer my perspective here.

First, from a scientific point of view, the WHO standards for drinking water are not all encompassing and do have their limitations.

Under the standards, the limits for certain chemicals in water are set because that is the best our latest technology can detect. Say chemical A can only be reliably detected at 5ppb (parts per billion) using the latest and best instrument X. Therefore, 5ppm is set as the WHO standard. This of course does not mean that chemical A is harmless at 5ppm.
Sometimes, chemical B may be harmful at 2ppb but because our water treatment plant can only economically reduce its concentration to 2ppb, 2ppb becomes the standard for chemical B.
WHO standards set limits for about more than 100 parameters but there are easily tens of thousands of chemicals out there. Can you be sure that these chemicals are not in your water and if they are, they are harmless?
The standards mostly cover single chemical substances. In many cases, mixtures of substances (e.g. heavy metals) can actually exert a synergistic effect, making the cocktail more deadly than the sum of the individual components. However, water regulators are starting to wake up to this fact and steps have been taken to categorise several substances into a single group under a single standard.
To be sure, most of the toxicology studies on which a limit is set are based on animal studies. Let's say chemical C has no adverse effects on a guinea pig population at 1ppb so 1ppb is set as the standard. (This is grossly simplified for illustration purpose.) Can this 1ppb be translated to humans? This can go both ways - the value can be higher or lower in humans but nobody knows for sure.
Even for those rare standards based on human studies, a large percentage of them are still short term studies. Who can be sure whether the same chemical D (supposedly safe at 3ppb for a month) will be safe if consumed for 30 years?

Science aside... (Are consumers knowledgeable enough about the science? I myself don't know much about the technical specifications in my laptop. As long as it works, I am happy.)

More than scientific facts, the most important element in sales (as any good salesman should know) is psychology. Show the consumer a high-profile example of person poisoned by lead (or substitute your least favourite chemical here) in drinking water, you will have the masses starting to show concern about their water and whether they should get a filter. This is notwithstanding the fact that the high-profile case may involve extraordinary circumstances not shared by the majority. Or more often than not, a latest piece of research may publicise that toxic chemicals are found in drinking water. Yes, this should push the panic button of many people and herd them towards the latest filter.

Don't get me wrong. I am not against water filters. But people should be rational about such purchases and should never buy based on fear or peer pressure.

3. What is the major cause why these tend to be poorly maintained (because they forget to change, it is costly to change, do not know they have to change[perhaps the people who sell the filters to them did not mention it explicitly], etc?)

Again, you will have to do a consumer survey to find out the truth. But I suspect most consumers do not keep track of their water use as conscientiously as they should. Most water filters are rated for a certain capacity (e.g. 1000 gallons of ordinary tap water) before replacement. Or perhaps you can say that most water filters not as well designed as they should as there is no meter or indicator when the 1000 gallons have passed through it. To make things simpler for the consumer, some filter suppliers have specified a timeframe instead e.g. the filter should be changed every 6 months. Again, this can be misleading as the usage of the consumer can vary. A family of 4 filtering 10 gallons of water a day is quite different from an extended family of 10 requiring 25 gallons a day. However, I have also seen some filter models incorporating an indicator that change colour when it is time to change the filter. I have not tried these models but they should be useful if they work as claimed.

4. What kind of water filters are being sold in Singapore and which are the ones that are more likely to be poorly maintained?

Unlike in certain countries, the household filters here are mostly of the point-of-use type that does its filtration at the point of discharge (tap). Not surprisingly, the low-end ones are rather popular. They may come in the form of jugs or faucet attachments. Slightly more expensive will be the counter-top and under-sink models. These filters mostly consist of a sediment sieve, an activated carbon packing and possibly a ceramic piece or plastic membrane.

The higher end ones will involve reverse osmosis (the same process used in Newater treatment). Ultraviolet units are rather rare. Ditto for distillation units and deionisation units. (I am using the term "filters" loosely here as some of the above items are strictly speaking, not filters.) In recent years, air-to-water units (e.g. Hyflux dragonfly/dolphin) have come onboard the water filter/purifier market. In my opinion though, they needlessly use energy to produce clean water and are excruciating slow to produce a decent amount of water.

Again, a consumer survey will be useful to find out the answer but I bet the more unwieldy and troublesome to change the filter, the more likely it will remain unchanged.

Phytoremediation of Wastewater

2010-12-20T19:27:00.001+08:00

Hi Chen Ko,

Hope all is well with you. While researching on phytoremediation for wastewater, I chanced upon your blog.
http://waterqualityinsingapore.blogspot.com/2010/03/before-you-write-off-plant-as-weed-read.html

Your blog has enhanced my understanding of phytoremediation and its potential in SEA. In the blog, you mentioned Earthship Biotecture. Do you happen to know the company/inventor behind this concept?

Thanks.
Best Regards
I

Hi I,

Glad to hear that you find my post useful. From what I know, Earthship Biotecture was founded by Michael Reynolds. The idea of an Earthship is a self-contained living environment that maximises the recycling of water - closing the loop as they call it, and minimises the wastage of energy. Food is actually a "by-product" of the recycling of water. Though it does not mean 100% self-sustaining as in a spaceship, the concept is nevertheless useful as a model for future housing.

If you are seriously interested in Earthship, you can actually sign up at the website as a volunteer to help out in the construction of their current projects. Unfortunately, there are no projects in our region as they are mostly located in the U.S.

Or if you prefer to find out more before diving head-first into the physical work, check out the 2 books by Michael Reynolds.

Earthship
Water from the sky

Here is a review of book #2 that I have written for my campus library in 2007.

Do you want to harvest rainwater and recycle your wastewater so that you will never have to depend on public utilities? Perhaps you simply want to reduce your rising water bills. Or perhaps you are an environmentalist at heart and feel strongly about conserving such a vital resource like water. If you have any of the above goals, this book excels in illustrating the processes of rainwater collection and recycling of both grey and black water. Detailed designs are available for the reader to immerse into the bolts and nuts from choosing the right materials to building a functional system which includes water treatment for rainwater, grey water and black water. Numerous photos and illustrations enable the reader to visualise each stage of the construction. This is however not a science book since the scientific reasons behind most designs are not well explained. The reader is advised to find out more about the science from other sources. One major shortcoming is the lack of costing details, impeding the reader from gauging how economical such a system is. Even though the author claims that the recycled water is drinkable after treatment, there is no mention of any physical, chemical or microbiological test being done. The relevant tests would have strongly validated his claims. Despite the above inadequacies, the book presents plenty of useful hands-on information that many “scientific” books lack. It should be read by anyone interested in rainwater collection and wastewater recycling.

Boil Water Advisory due to power outage in New Orleans

2010-12-03T22:29:00.002+08:00

I recently came across this article (Boil Water Advisory In Effect For Orleans Parish East Bank) about New Orleans which was best known for its devastation by Hurricane Katrina in 2005 from a water point of view. (Yes, I know that it is well known for its Madi Gras and the Cajun influence but hey, this is a water blog.)

What caught my eye was "It's the most widespread boil-water order in New Orleans since Hurricane Katrina, affecting more than 300,000 people." Basically a 10-minute (yes, only 10 minutes) power outage at the local water treatment plant prompted city officials to declare that all tap water for drinking and cooking should be boiled for at least a minute. Bathing is fine as long as you keep your mouth shut. This advisory lasted for a day or so.

Again, I stressed that energy and water are intimately linked. Remember the Matrix Reloaded, electricity is supposed to be the system all other systems are built on. Knock it out and other systems will follow.

Of course, if the power outage lasts longer, how are you going to boil water with your electric kettle? If your gas supply is down, the stove becomes out of the question too. Therefore, it is never a bad idea to have a good water filter handy for such emergencies, if not for routine use.

Water quality in Sungei Buloh Wetland Reserve (SBWR)

2010-12-02T23:42:00.003+08:00

I just found my article has been published in Wetlands. It has taken a long time to reach print so I must admit the data is slightly outdated (2008).

Overall, the water quality in SBWR was either relatively unpolluted or weakly polluted. Some concerns are raised regarding the levels of

dissolved oxygen (DO), phosphorus, nitrogen (ammonia and nitrate) and Escherichia coli. Regarding that last bit about E. coli, please do not comtemplate swimming in those waters as the E. coli count was sometimes found to be above the EPA limits for primary contact activities e.g. swimming. In case you are wondering where E. coli comes from, it is found in the human gut and normally enters water via human fecal matter. I guess you can imagine the rest. (See previous post on a similar indicator microbe, Enterococcus.)

Are our streams dying?

2010-11-30T19:27:00.000+08:00

First, it was Ngee Ann Stream - formerly natural (or "naturalised") stream surrounded by beautiful secondary forests was cleared and replaced by a canalised version. (See former posts - 1, 2, 3)

Now, development or rather its effects have come to my favourite tributary leading to Sungei Ulu Pandan. On 2 visits to this tributary as part of my field trip for my course on Freshwater Quality and Biodiversity, it was badly polluted by an ugly layer of black oil floating on the surface. On the first trip, the only living macroinvertebrates (bugs) we could find were a couple of blood worms. The second trip proved to be much worse with ZERO bugs and this time, besides the black oily film, there was also a strong petrochemical smell, presumably from the oil. Most of the adjacent vegetation have also been stained by the oil. I am skeptical that the stream can survive the ordeal.

Where could this oil have come from? Further upstream was some road construction works and even further up, a golf course was being extensively cleared. Were they the culprits? Possible but no way to tell without further investigation.

There goes another educational site. It was already small to start with though we could still find dragonflies, damselflies, snails easily then. We even found the odd freshwater eel sometimes. Now, I will have to crack my head to look for another viable alternative.

I happened to see this recent article: Stormwater Runoff Disrupts Urban Stream Life. This study in Seattle basically says that stormwater carries many pollutants from the land into water bodies, killing or driving off aquatic life. Though nothing new, it reminds us of the interconnectivity between human activities and nature and especially the relationship between land use and water.

At first sight, land and water appear separated and independent but never forget that water in stream does not just come from upstream, it comes from a much wider land area known as the watershed. Anything bad going down in the watershed can eventually find its way into the stream and even the sea. I heard of this interesting remark that "we all live downstream", meaning our (or human) actions will often come back to haunt us, whether for good or bad depending on what the said actions were.

Figure: Black oily stuff floating down from upstream. Though the aquatic plants managed to block off the bulk of it, the oil inevitably trickled downstream to kill off the bugs in the stream.

Figure: Another view of the oil

Do we really need water filters 2?

2010-11-19T23:03:00.003+08:00

Here is a follow-up to the previous post.

Thanks very much for your very detailed explanations.

Just wonder, since "New Water" is quite pure and will be gradually added to our reservoir, how can consumers be protected from any harmful effect that it might bring about ? Is water filter one of the solutions ? Any other ways ?

I would not worry about any harmful effects from Newater. Newater is produced by treating the effluent from water reclamation plants using microfiltration, reverse osmosis and UV disinfection. Most (but not all of course) impurities e.g. salts, metals, organic compounds, would have been removed. This is probably already very close to pure water. Anyway, we are not drinking Newater straight unless you have accumulated cartons of Newater and drink exclusively from them. As you pointed out, Newater is mixed in a small percentage with reservoir water so I will worry more about other sources of contaminants.

I missed out a point in the previous post. The water from the water works is routinely tested and compared against WHO (World Health Organisation) drinking water guidelines. Let's assume that the WHO guidelines are adequate safeguards of the water's suitability for drinking, does this mean that water from the tap should be good to drink? Perhaps not because most of the testing and sampling are done right at the output from the water works. The water from the water works then has to flow through a complicated distribution network before reaching your home.

How many of us routinely test the water from our taps? Is there leakage along the way between the water water and our tap? Could the water have come into contact with sewage which may have also leaked from sewage lines? Or perhaps other contaminants have entered the cracks in the lines? What about the pipes and fixtures themselves? Lead, copper, zinc from old pipes could have gone into the water as the pipes corrode. All these scenarios can be real.

Is there other info that might help consumers in their cost benefit analysis as water filters incur recurring cost.

Our drinking water and sanitary standards are considered quite impressive compared to many countries. We do not have epidemics of cholera, typhoid or dysentry as seen in some developing countries or cases of severe heavy metal poisoning that turns whole villages into a public health nightmare. Therefore, most of our concerns are on potential or unconfirmed long term health effects e.g. chlorine, fluoride (update: check out Fluoride Action Network for arguments against fluoridation). This of course makes a quantitative analysis of costs and benefits difficult. For example, how do you quantify the cost of a cancer that may or may not manifest in 30 years time? I suppose the best we can do is a qualitative analysis. Is the risk of cancer (in 30 years time) worth the $300 you spend per year in water filters? Or perhaps is that $300 worth the peace of mind you get from filtering your drinking water? Obviously different people will have different opinions here.

Also, Is there any independent studies being conducted on the water filters and do they really live up to what they had claimed ?

The most widely used standards I have come across are the NSF/ANSI (National Sanitary Foundation International/ American National Standards Insitute) standards. (Other countries e.g. Japan also have their own standards for water filters. Ditto for other organisations such as USEPA and American Red Cross which certify/approve various water treatment units though some of these units are for outdoors use.) NSF/ANSI 42 applies to improvement of aesthetic effects in drinking water using a filter while NSF/ANSI 53 applies to mitigation of health effects from contaminants in drinking water. Water filters can be certified under either or both of these standards though if you are more concerned about your health, NSF/ANSI 53 will be more useful.

However, even if a water filter is certified under these standards, do check the kind of water quality parameters it is tested against. One filter may lay claim to reduction of turbidity and bacteria while another may be certified to reduce only iron and hydrogen sulphide. These are the fine points most consumers will miss out. (Even the sales staff may not be knowledgeable enough.) Make sure you know what contaminants you are concerned about and check whether your water filter is certified to remove those contaminants.

To complicate things a bit more, these standards can apply to the filter component (cartridge or element) itself or the whole system (filter housing + cartridge). Even though a filter element is certified, if the housing has a leakage, the filtered water can be cross contaminated by the inflow. If possible, get a filter that is certified as a whole system and not just the cartridge itself.

On a final note, an uncertified filter does not necessarily means that it performs poorly. Remember, certification costs money and that cost will certainly be reflected in the price of the filter.

By the way, may I know which is the Doulton gravity filter you are referring to as they had quite a few models ?

The model that I have is the stainless steel gravity filter, STS-S-ATC (http://www.arkwater.com/stainless.html) which uses the ATC Super Sterasyl filter element (http://www.arkwater.com/ceramiccandles.html). It is the smallest model available here (I have seen a smaller one sold overseas though) so if you have a big family, it may not be enough. Also note that the ATC Super Sterasyl filter element is designed to remove microbes, particulates, metals, organics, chlorine etc. It is very versatile but that comes at a price (monetary and otherwise). Besides the higher price, its filtration capacity is reduced compared to the other filter elements from Doulton. If you are chiefly concerned about chlorine, you can consider getting the STS-SS10 (http://www.arkwater.com/stainless.html) instead.

I personally advocate getting a gravity filter because of its beauty in operating without electricity and water pressure. However, it can be a pain to keep scooping water into the filter and pouring out the filtrate from the lower chamber. If you find this too painful, you can consider getting a counter-top (model: HCP-Single) or under-sink (model: HIP-Single) housing incorporating the Supercarb filter element (or candle as they call it) (http://www.arkwater.com/residential.html). (Their webpage shows the above models fixed with their Ultracarb filter element which is higher end. I suppose if you ask for the Supercarb, the price should be lower.)

Thanks & Regards.
L

Do we really need water filters?

2010-11-15T19:30:00.002+08:00

I got an enquiry about water filters and their necessity. I have posted my reply below. (As a side note, I am currently working on a project to determine the effectiveness of water filters in reducing contaminants in our tap water.)

Hi

I was searching for water filters and happened to see your blog
http://waterqualityinsingapore.blogspot.com/

I had a few queries and hope that you could comment or advise :

May I know whether the tap water/new water in Singapore is safe to be consumed directly without boiling ?

The tap water in Singapore has its quality benchmarked against World Health Organisation (WHO) drinking water guidelines. Its water quality meets and sometimes even surpasses the requirements given by WHO. From this perspective, yes, tap water in SG can be consumed directly.

As for boiling, it is most effective at killing microorganisms in the water. Boiling can prevent you from getting a case of food poisoning or diarrhea if the water is contaminated by pathogens. However, boiling is not good at removing chemical contaminants such as heavy metals, organic compounds or even chlorine if they are present in the water.

I heard from salesman selling water filters that tap water contain chlorine which is not suitable to be boiled as it may produce trihalomethanes (THMs) which may cause cancer over long period of usage.

Yes, our tap water contains chlorine for its ability to prevent the growth of microorganisms in the water. But the concentration is still within the limits given under the WHO guidelines.

Yes, chlorine can form trihalomethanes (THM) under the right conditions. First, you will need organic compounds in the water to react with chlorine to form THM. Usually the organic matter content in our tap water is too insignificant to form any THM. Our tap water is normally slightly acidic (< 7) so THM, if any, will form very slowly as they favour a high (alkaline) pH.

To be fair, the most well known member of THM, chloroform, is (only) a confirmed animal carcinogen with unknown relevance to humans. (Of course, I will rather not take my chances with ingesting chloroform.) The other members of THM are much less studied regarding their toxicity effects.

On the other hand, even disregarding THM, chlorine can be toxic in other ways - by itself or reacting with other chemical compounds IF its concentration in water is high enough. I have heard of water treatment companies in other countries dumping large doses of chlorine to disinfect their tap water and in the process, causing health problems in their consumers e.g. tumours, miscarriages. However, the chlorine in our tap water is definitely much lower (again according to WHO guidelines) as we routinely test it as part of our students' training.

If that is the case, does it mean that we need to buy water filters in order get rid of the chlorine before boiling the tap water for making hot beverages ?

Just like issues on food and medicine, water is surrounded by much controversy, especially on the health effects of its components, whether for good or bad. Chlorine in water is no exception. I can't say for certain that chlorine is completely harmless. This is complicated by the fact the health effects are usually only seen in the long term. Performing unbiased studies on human health for the long term (25, 50 years) will be difficult so no one can be sure what the long term effects are.

My thought is if you are worried and you can spare the budget (remember, filters are consummables and require constant changes), do go ahead and get yourself a good filter to reduce the chlorine content in tap water.

May I know what are the impurities that are still present in the tap water/new water and what are the suitable filter to address them ?

Despite its clear appearance, our tap water contains lots of impurities. (Try googling for "PUB tap water quality".) Water of high purity (Newater by itself is quite pure though) is normally used in microelectronics/wafer fabrication, medical applications, pharmaceutical manufacture. (Actually, high purity water is considered "agressive" and may be bad for health. Oh boy, another can of worms here.)

One impurity of notoriety is fluoride. Our tap water is intentionally fluoridated (addition of fluoride) to fight against tooth decay. However, studies (again inconclusive) have shown that fluoride can be bad for health (arthritis, mutagenicity etc.) and unlike decades ago, we are already getting enough fluoride from our food and toothpaste. Do we still need fluoridation then? Like chlorine, may factors come into play in determining whether fluoride really does exert those negative effects e.g. concentration, time frame. And like chlorine, if you are worried, you should get a filter to reduce fluoride. (Update: check out Fluoride Action Network for arguments against fluoridation)

I saw "arkwater" filter being mentioned, is it advisable to get it to remove the impurities present like chlorine ?

I believe that the Doulton gravity filter (get the high-end one) from Arkwater is a very good overall filter to remove many contaminants in water - microorganisms, heavy metals, organic compounds, fluoride, chlorine. This is especially critical for disaster or emergency relief when you do not have a clean source of water. Being a gravity filter, it does not need pressure (e.g. water mains) or electricity (what if your power is down). In addition, the filter can handle thousands of gallons of water before needing a replacement. Even if your intention to remove (or reduce) contaminants of unconfirmed health effects as in your case, the filter should still perform beautifully. (I must stress that I am in no way affiliated to Arkwater and derive no benefits from their sales.)

Figure: Doulton (aka British Berkefeld) fluoride removal filter cartridge. You will need this additional cartridge to remove fluoride as the others cannot remove this controversial compound.

Figure: Doulton (aka British Berkefeld) ceramic filter cartridge - the ATC Super Sterasyl model - the highest end for their line of gravity filter cartridges. It contains activated carbon to remove chlorine and organic compounds. Also inside is a metals removal medum.

Figure: Shell of the Doulton filter. The top compartment holds the filter cartridge and accepts raw water. Raw water filters through the cartridge by gravity and you get clean water in the bottom compartment.

At the end of the day, what I am trying to say is beware of sales tactics based on fear only with little or no truth. I am not saying that you should not get a good filter for your domestic use. But if you do, your decision should be based on sound judgement of facts or at least probabilities after weighing the costs and benefits sufficiently.

Thanks & Regards.

Outdoor Education Conference (27 Oct 2010)

2010-10-25T23:20:00.000+08:00

For those of you heading to this conference (walk-in registration is still available), you may be interested to know that I am presenting 2 sessions on 27 Oct 2010 (Wed).

Details for the concurrent sessions are as follows.

Session	Date	Time	Presenter/s	Venue

Water Quality Monitoring as a Tool for Environmental Education

27 Oct

09:00am-11:00am

Mr Kwok Chen Ko Singapore Polytechnic, Singapore

B08-09

Water Quality Monitoring as a Tool for Environmental Education

27 Oct

11:30am-12:30pm

Mr Kwok Chen Ko Singapore Polytechnic, Singapore

B08-09

Objectives
1. Appreciate the importance of water quality to the health of the environment

2. Understand how several fundamental water quality parameters interact with aquatic life
3. Recognise the potential and challenges to water quality monitoring in Singapore

Target audience
Teachers/ Practitioners/ Coordinators of outdoor education programmes

Brief Description of SessionBesides the usual classroom talk on water quality monitoring, we will go through some of the instruments used in the field via a demonstration.
1. What is water quality
2. The basic water quality parameters
3. Measuring these parameters in the field
4. Challenges to water quality monitoring in Singapore
5. Resources for water quality monitoring

Is Pasir Ris water really unsafe?

2010-10-10T01:05:00.001+08:00

As a follow-up to the news update on the fecal bacteria laden water of Pasir Ris, this news may throw more questions (instead of light) on the issue of poor water quality at Pasir Ris.

First, a quick summary. A press release from NEA (Sep 2010) stated that the water at Pasir Ris Beach is unsafe due to the off-specs level of Enterococcus (a bacteria) in the water. Enterococcus is supposed to indicate the level of fecal contamination. More Enterococcus of course means more fecal contamination, implying a higher possibility of the presence of human pathogens.

Why don't we analyse the water directly for the pathogens? There are simply too many pathogens to test for so going down this route will easily lead to a logistical nightmare. Therefore, we stick to an indicator organism, something that is strongly linked to humans. Since Enterococcus (supposedly) comes from the human gut, its presence is (supposedly) sufficient to prove the contamination of the water by humans.

Going back a bit backwards in the history of water quality testing, the title of indicator organism for fecal contamination used by held by a group of bacteria known as coliforms. Not surprisingly, coliforms are also found in the human gut and its presence used to conclude the presence of human contamination. Unfortunately, coliforms are also found in other animals and soil. Some years back, Enterococcus has taken over this position as it was found to produce a better correlation to many human pathogens found in sewage. (Opps, the summary seems a bit longer than I initially thought.)

Ok, enough of summarising. Check these out:
1. Evaluation of Chemical, Molecular, and Traditional Markers of Fecal Contamination in an Effluent Dominated Urban Stream

2. How To Define "Safe" Water? Water Pollution: Southern California study highlights the limits of bacteria used as fecal indicators

The study basically argues that even Enterococcus is not a good enough indicator for fecal contamination in water. Why? Because it can also be found naturally in the river bed (in the study). In fact, it can actually grow in the river bed under favourable conditions i.e. good nutrient availability. Therefore, a bacterial count using Enterococcus tends to be overestimated with regards to the actual fecal contamination. (Granted, the study took place in fresh water and not seawater. But being such a versatile creature, Enterococcus can tolerate a wide range of conditions - pH, temperature, salinity, presence/absence of oxygen so it will not be surprising to find it thriving nicely in seawater.)

Is the water at Pasir Ris safe then? Your guess is as good as mine.

However, the study did recommend a substitutre for Enterococcus - something known as human-specific HF183 Bacteroides. This bacteria is supposedly (?) found only in the human gut. Testing for the presence of its genetic material will provide an accurate (?) picture of the amount of fecal contamination in water.

Will it really work?

Me? I will wait for the next piece of study to throw a spanner into this theory :-)

Digging around at Pandan Reservoir

2010-10-08T01:40:00.001+08:00

I managed to steal some rare spare time to tag along with a NUS team and JH for a biodiversity survey of the floating wetlands at Pandan Reservoir.
What floating wetlands?!? If you have been observant enough, Pandan Reservoir and Lower Seletar Reservoirs have several bunches of plants floating right in the water. No, they are not aquatic weeds that suddenly grow up from the reservoir bed. They were deliberately placed there as an experiment(?) to improve the water quality. (Check out my previous post on how plants can clean up water.)

Figure: One of the floating wetlands at Pandan Reservoir. Notice that the plants on the wetland are different from those on the shore.

These floating wetlands are actually made of a floating plastic matrix above which a layer of coconut husks is embedded. The plants are allowed to extend their roots through these 2 layers.

Will they float away? No. Short of an extreme weather event, each wetland is anchored to the bed by rocks.

These floating wetlands dotted the northern shore of Pandan Reservoir. Are they effective in improving the water quality? My opinion is there are probably too few of such wetlands to make a difference to the reservoir as a whole. (Did I say that this was just an experiment?) Any change in water quality is probably localised and restricted to the immediate vicinity of the wetland. You will likely need a series of these wetlands to ring the entire reservoir. Maybe add another ring or two.

Figure: By the way, we had the luxury of sitting in a PUB motorboat as we passed by several floating wetlands

Next question - do bugs (macroinvertebrates) live under these wetlands? If so, what kind of bugs? These are interesting questions as my usual bug surveys were performed in running water (e.g. stream) or stationary water (e.g. pond). In the substrate of a floating wetland?!? No one knows...

Figure: Digging and scrapping and sweeping through the underside of a floating wetland

Figure: Voila! You can see a Marble Goby (top left) and a shrimp (bottom right) clearly here.

No so clear in the figure include: backswimmers (many!), unknown zooplankton (?) (many!), copepods, chironomids (your wriggling blood worms), a few damsel flies, dragonfly nymph exoskeletons (surprisingly, no live nymphs though we can see adult dragonflies happily scuttling through the air), chironomid eggs and pupa cases, mayflies (!). Looks like the biodiversity in these floating wetlands ain't so bad.

Figure: No, this is not part of the wetland survey. Actually, this is the primary task of the NUS team - deploying sampling traps in the reservoir to find out what kind of bugs can be lured into them.

Figure: On the way back, we stopped by this odd looking contraption floating in the middle of the reservoir. (Actually, it a buoy housing sensors though no one in the team knows what kind of sensors.) Of course, data from the sensors are transmitted telemetrically to some receiver on shore. Everything is this package is powered by solar energy as evident by the solar panels. See a previous post on descriptions of a similar setup. Oh, we didn't stop here just to admire this blue box. The NUS team actually wanted to catch some spider specimens here as a healthy population of spiders seems to be thriving on this buoy in the middle of nowhere.

How to reduce flooding in Singapore? Harvest more rainwater!

2010-09-18T23:16:00.003+08:00

Harvesting of rainwater may sound foreign to most of us even though this term is commonly used in other countries. It simply means collection and storage of rainwater. It may be on an individual, residential, community or even national basis.

Actually, Singapore has been harvesting rainwater for a long time on a national basis. From PUB's webpage, two-thirds of the land area here is available for rainwater catchment (Yes, right, "catchment" is more commonly used here).

(Figure: www.pub.gov.sg/water/Pages/LocalCatchment.aspx)

Is so much of our area covered by reservoirs? NO! It means that land (residential, industrial, recreational, waste etc.) is used to funnel all that rainwater into reservoirs. For example, rainwater falls on rooftops, flows into drains which lead into canals, ultimately joining up with a reservoir. Because of the flash floods in June, everyone now knows that Orchard Road is part of the catchment area for the Marina Reservoir. Talk about practical environmental education.

Indeed a very clever system to alleviate the shortage of water in this densely populated island. However, it suffers from a few drawbacks.

One, in times of heavy rainfall, no way will the reservoirs be able to hold so much water. The natural thing to do is to drain the excess into the sea. (E.g. the Marina Barrage is well touted to be able to do this in the event of heavy rains.) This of course means a waste of fresh water. AND IF the excess CANNOT be drained (e.g. blockage of some water way), flooding will result. In the (good?) old days when Singapore is still a tropical jungle, most rainwater will be soaked up by the vegetation and soil. But with the increase of built-up area, we no longer have such a luxury. Most rainwater will flow over the ground surface straight into drains and canals or perhaps accumulate in some low lying area as a flood.

Another challenge of open reservoirs like ours is the loss of water through evaporation. In the dry months, the water level in the reservoirs drops not only because of the lack of rainfall but also through the above mentioned loss.

This article predicts that the rainwater harvesting (RWH) markets in Europe and India are set to experience high growth rates in the coming years due to a rising fresh water shortage. More RWH systems will be installed at the residential, commercial and industrial levels.

Guess what? This is nothing new in Singapore! Changi Airport has such a system. Nanyang Polytechnic has one too. The airport is reported to satisfy one-third of its water demands in this manner, saving $390 000 per year. Such water is normally collected on the roof-top and undergoes minimal treatment for non-portable use e.g. toilet flushing, firefighting drills, watering of plants.

Imagine... if we have more of such systems, not only will our reservoirs be less stressed in times of heavy rain, there will also be less loss of precious fresh water through evaporation.

If your interest has been piqued, how do you set up a RWH system. SIF Technologies is selling a "chemical free RWH system". Chemicals are sometimes added in conventional water storage to discourage microbial growth. (Chlorine in PUB water does this job.) In the case of SIF, they are using a proprietary non-chemical means to do the same thing.

But RWH can be simple and cheap. Consider this 3rd world method of RWH. However, remember to always discard the first 10min of so of rainwater as it may contain pollutants from the air or your roof-top.

Figure: using a tin roof to collect rainwater (Water for Life, Hesperian Foundation)

Figure: My own version of a RWH system for use in a high-rise flat from a project several years back. (Naturally, we can't have every household in a HDB block harvesting rainwater. I suspect only the top floors will get any significant amount. The other concern is not to have a high-rise RWH system becoming killer litter.)

Oh, before you rush out to install a RWH system, here is an extract from Singapore Law.

SEWERAGE AND DRAINAGE ACT

PART V PROTECTION OF WATER RESOURCES
Prohibition on extraction of water
No person shall, without the approval of the Board (PUB), construct any works for taking or intercepting water from any place or sea, within the territorial limits of Singapore.

However, I believe the law has been relaxed for residential installation provided the storage tank is less than a size of 5x2x2m. Anyting bigger will require a water-borne fee to be paid. But if you are planning a system for your company or school, you still have to go through the bureaucracy for permission. One last point, check out the guidelines for collection of rainwater at NEA.

(Update: Rainwater Harvesting Seen as Solution for Drought and Flood Control: In Kenyan cities like Nairobi, rainwater harvesting is seen as a solution to multiple problems.)

Water resources from Loughborough University

2010-09-15T23:50:00.000+08:00

Loughborough University's Water, Engineering and Development Centre (WEDC) has a new knowledge base where 150 books, over 1700 conference papers and hundreds of other knowledge outputs are available for download FOC if you register.

Topics range from water supply, sanitation, emergencies/disasters, lessons from floods and many more.

http://wedc.lboro.ac.uk/knowledge/know.html

Revisiting Pasir Ris

2010-09-14T22:31:00.001+08:00

Thanks to Ria for her post on Pasir Ris water quality deteriorating due to the high concentration of enterococcus bacteria in the water.

An explanation of the situation from NEA press release (7 Sep 2010)
"According to results from a study released by NEA in 2009 during the last annual assessment of water quality at beaches, Pasir Ris beach’s water quality is affected by various possible sources, including minor leakage from older sewers, moored vessels, animals, as well as discharges from small-scale Sewage Treatment Plants (STPs) that presently serve the more remote areas in Pasir Ris. The low water currents in the concave part of Pasir Ris beach are not effective in diluting and dispersing the discharges."

I do not have the answers to most of the whys and hows in this issue. Instead, I will pose a few more questions. (Does this complicate the issue further?)

Fish farms in the vicinity

I believe the staff on these farms dispose of their bodily waste directly into the sea straight without treatment so yes, this can be a source of the E. bacterium. (Anyone care to refute the part on direct disposal?)
Fish waste is another issue altogether. Yes, they may decompose and cause the dissolved oxygen level to plummet but enterococcus??? Not likely as the bacteria normally comes from humans.

Aging sewage treatment plants (STP) in Changi and Tampines

Can anyone throw some light on these plants? Where are they? Industrial (probably)? What kind of industry? What is in the sewage - human, animal or industrial waste?
Doesn't sewage go into the PUB sewers?
Why are they allowed to discharge unhealthy effluent into our waterways? Any discharge into a watercourse must be approved by NEA under the trade effluent regulations of Environmental Protection and Management Act.

Unfortunately, under the same regulations, there is no mention on the limit of coliform, enterococcus or even bacteria for a discharge.

The closest will be BOD5 (biochemical oxygen demand for 5 days) under the regulations. (In simple terms, BOD5 is a measure of the biodegradable substances e.g. faeces, urine, food in the water.)

"The 5-day Biochemical Oxygen Demand at 20° Celsius (referred to in this paragraph as BOD) and the Chemical Oxygen Demand (referred to in this paragraph as COD) of any trade effluent analysed in accordance with regulation 11 shall not be in proportions greater than those set out below:
(a) 50 milligrams per litre of BOD and 100 milligrams per litre of COD where the trade effluent is discharged into a watercourse other than a controlled watercourse"
I assume the waterways which lead to the sea off Pasir Ris are non-controlled watercourse since they do not go into a reservoir. Still, 50mg/L of BOD5 is easily exceeded by normal domestic sewage (100 - 300mg/L). (Agricultural or food wastewater may go into the thousands in terms of BOD5.)

How efficient are these STP in treating sewage i.e. percent reduction in BOD5? Did anyone check whether their discharges exceed the limits set out in the trade effluent regulations?

Nevertheless, it is entirely possible that the discharge can pass the BOD5 test but yet contains enough human waste to give a high enterococcus count in the sea.

Sembawang Park

The water quality off Sembawang Park (also given in the same report) seems fine. Being located along the Johor Straits as is Pasir Ris Park, I imagine the seawater dispersion there is as dismal. Perhaps, the smaller number of fish farms and the lack of aging STPs and leaking sewers do make a difference.

Introducing the British Berkefeld filter - something you can count on when the chips are down

2010-09-10T04:57:00.001+08:00

The latest earthquake in New Zealand (Christchurch and surrounding area, 4 Sep 2010, 4:35a.m. Saturday, 7.1 magnitude) got me thinking about the supply of water again but this time round it prompted me to pen it down. (Long post as follows)

If you have been following this year's (2010) natural disasters - earthquakes in Haiti, Chile; flood in Pakistan, public water supply has always been a fragile creature. Infrastructure can be destroyed, piping and storage tanks can be broken.

In Pakistan, the deluge caused natural sources of water (e.g. wells, springs, streams) to be contaminated with whatever the flood water carried - human and animal waste, pathogens from corpses and carcasses, pesticides from farms, heavy metals from industry. In the short term though, it was the water borne diseases that caused the most problems - diarrhea, dysentry, cholera, typhoid etc. The breakdown of sanitation and water supply led to a nightmare for public health (probably nowhere near top notch even before the flood).

Bottled water naturally became a valuable commoditity as seen in Chile when it became one of the top looted items (together with bread and candles). I imagine the same would have occurred in Haiti if there was enough bottled water to go around to be looted.

Being a developed country, New Zealand was spared from serious looting (some still took place according to the news) or outbreaks of water borne diseases. Heck, no one was killed by the quake as according to some experts, the strict building codes to quake-proof its structures have helped. (Compare against 230 000 killed in the Haiti quake.) Nevertheless, the sewage pipes were broken in the quake, allowing sewage to mix into the drinking water supply which probably probably suffered from broken piping too.

Consequently, residents in affected areas were asked to boil their tap water for drinking. I am thinking: these people are lucky (despite the quake and all). They still have electricity or/and gas. Imagine... if you have no gas, no electricity and only sewage infused tap water, how are you going to boil your water?

Imagine some more.... the NZ scenario (without the gas and electricity) happens right here in good old SG (assuming we survive the quake), do you have a wood burning stove and charcoal at home? How about a camp stove with extra gas tanks? The lucky ones will be those NOT using piped gas. The years of effort to heft around those gas cylinders would have been worth it.

Do you have Aquatabs on hand? Bleach? Do you know how much to add into water? Personally, these are not my favourite choices because of strong chlorine taste and many health controversies of overchlorination. By the way, if you opt for bleach, only use the straight ones without extra ingredients e.g. scent.

Boiling is good if you can do it but it only removes the bugs and not all the other nasty stuff (pesticides, metals) in the water. Imagine having a Pakistani scenario here. I will boil my water before running it through a good filter.

I personally recommend the British Berkefeld (or Doulton) gravity filter. (In America, it is sold under the name of Berkey.) No water pressure, no electricity needed. Simply pour your water through the top and collect clean water at the bottom. The key element in the setup is the filter candle with the ATC SuperSterasyl being the best. It has a ceramic outer shell impregnated with silver. The ceramic physically remove microbes and particulate matter from the water while the silver suppresses bacterial growth. The water next enters a granular activated carbon core containing a metal ion removal medium (works by ion exchange, I believe) to eliminate many organic compounds (e.g. pesticides), chlorine and metals (e.g. lead, cadmium).

Figure: The external setup of the British Berkefeld stainless steel gravity filter minus the faucet which should be attached near the bottom. It is certainly not small (this is already the smallest stainless steel model) so it should be used for the family or small group at a static location.

Figure: Opening the lid reveals 3 holes for fixing a filter candle each

Figure: The heart of the filter system - ATC SuperSterasyl filter candle. Notice the white ceramic exterior. Water enters through the ceramic and filtered water leaves through the black nozzle on the right.

Figure: The top portion is removable for fixing the filter candles. Filtered water goes into the bottom portion for dispensing via a faucet.

Having one of these filters will certainly add a great degree of water security to any family. And if you are involved in overseas community projects, keeping one with you serves as insurance, especially if you are not sure of the water quality or source of your drinking water.

This line of filters may be procured locally from Arkwater. Of course, I am in no way affiliated with the company except for purchasing these filters from them.

Sembcorp water technology prize (Sec 2 - JC2)

2010-09-09T16:54:00.001+08:00

Just saw the poster below even though my colleagues have mentioned to me that they are involved in the competition. More details are found on PUB's webpage here. If you are considering to participate, the deadline is 18 Sep 2010.

Apparently, there is this push into membrane technology as the solution to getting clean water. Membrane technology is certainly cheaper and more energy efficient compared to traditional distillation. Theoretically, it can remove almost any impurity (salt, organic compound) in water. A membrane is basically a filter with very tiny pores. Depending on the specifications, some are small enough to block off microbes while others can block off even dissolved ions like sodium and chloride, allowing only water molecules to pass through. Seawater and heavily contaminated water can be made into potable water.

Naturally, pushing water through such tiny pores requires lots of pressure (and energy) so using membrane to purify water (e.g. reverse osmosis) is by no means cheap but prices seem to be dropping all the time.

Other challenges. Membrane fouling is a major problem. After some time, contaminants accumlate on the surface of the membrane till it can no longer function efficiently. It is time to either clean the membrane or replace it entirely. To prolong the operating life of a membrane, it is essential to have good pretreatment. In other words, you need to have many steps before the actual membrane itself to filter off increasingly smaller contaminants. Imagine having several filters of decreasing mesh size so that the final filter will not be stressed by a big load of contaminants.

Of course, this sort of setup comes with controls and maintenance operated by skilled personnel. Though there are now remote control interfaces, allowing a treatment unit in say, Africa to be controlled by a technician in America, you still need boots on the ground to attend to certain maintenance tasks. Therefore, this technology is still not so useful for rural areas without the presence of skilled personnel. Very often, even with skilled personnel present, the local population may not be able to operate the treatment unit once these personnel leave.

But for Singapore, sure, no problem. Membrane technology is the way to go!

A quick update for the past months

2010-09-08T22:35:00.003+08:00

I would like to convince myself (and you) that my packed work schedule has prevented me from posting anything since the end of May. I know it is a shame but I am also sure that inertia has played a large part - not having posted for so long propagates the said behaviour :-)

In part to prove that I am really "busy" and to update you on the past activities, here is a summary of my "work".

June - July
Conducted "Freshwater quality and biodiversity" course for Crescent Girls, Henderson Sec Sch, Clementi Woods SS, Queensway SS. It was back to a tributary (sort of a naturalised drain) of Sg Ulu Pandan for more water quality testing and bug hunting.

Figure: The group hunt (for bugs)

Figure: Don't forget the water quality parameters

Figure: Sorting out the spoils of the hunt

Figure: A rare find - freshwater eel - too small for unagi though

Figure: The common Dragonfly nymphs though perhaps not so commonly seen by the students

Conducted a round of 6-day intensive AEM (advanced elective module) "Water quality and pollution".

Figure: On first sight, nothing wrong with the scene. But if you look closely enough, lots of people are looking down on their pants and shoes. This is what happens when you venture out in the wilderness in the rain and through knee high vegetation. All manner of creepy-crawlies are out their homes, latching on to the hapless passer-by (i.e. us).

Figure: Part of Ngee Ann Stream. Looks like another canal except that this used to be a natural stream with thick secondary forest on both edges. See next figure.

Figure: The same part of Ngee Ann Stream as the figure above but a year back. Note the vegetation stretching right to the edge of the secondary forest stream

Figure: An unusual find - a catfish struggling against the current in the "canalised" Ngee Ann Stream. Why was it doing so? I have no idea. Perhaps it should have just flowed along with the tide of change as what the rest of the stream did when it gave way to "development".

Figure: Due to the earlier heavy rain (what else is new in Singapore?), the whole canal was flooded, preventing the students from sampling the water (too dangerous).

Figure: The same part of the canal as the figure above but in drier times and more than a year back.

Figure: I simply can't resist putting in this routine group photo. Must show that the participants are in good spirits, right?

Singapore International Water Festival (27 Jun 2010)

Once again, I was roped in to organise the event "Amazing Greenviron Challenge" - an environmental quiz of sorts with indoor and outdoor components at the Marina Barrage. Weather was terrible in the morning so the outdoor part has to be moved indoors. (Right, rain was indeed heavy in June, giving rise to the shocking floods in downtown Singapore.)

Figure: Only 1 photo to show you here - the super group photo with organisers, student helpers and participants.

(Are we not done with the summary yet??? Afraid not... Did I mention that I had a tight schedule then?)

Water Quality Monitoring (WQM) (19 Jun 2010)

Amidst the tight schedule, I managed to sneak in a round of WQM with Team Seagrass at Chek Jawa.

Figure: On this rare sunny June morning, my students prepared their equipment for WQM.

To top it off, I attended the 4-day Wilderness Medical First Responder (WMFR) Course by OBS (Outward Bound Singapore) on Pulau Ubin. More on this in a later post.

Figure: WMFR participants and our dummies

WQM at Pasir Ris

Ah yes, the problematic kid on the block with regards to water quality - Pasir Ris Beach. (The latest advisory on its "fair" water quality is found here.) We checked out this notorious locale on this rainy July morning. Perhaps unknown to most people, this stretch of sand hosts 2 significant patches of seagrasses even though they are not monitored by Team Seagrass. (Some of the Team's members do however check out the seagrasses here in their own capacity.) And since there are seagrasses here, my team will of course be interested in the WQ.

Figure: 1 patch of seagrasses near Sg Loyang

Figure: The 2nd patch of seagrasses near Sg Tampines. I was told that there is a smaller patch further west near the end of Pasir Ris Park. We did not check this one out though.

Who's who in the oil spill response team (Crude oil spill off Changi East)

2010-05-28T12:29:00.000+08:00

Based on the reports (check out my previous post for links) on this latest oil spill in Singapore waters, the response is run-of-the-mill. Floating booms, dispersants and skimmers are traditional methods to combat spills of all sorts but they have their limitations. And sometimes, they are plain inappropriate to use.

For example, in 2000 & 2001, 2 phenol spills occurred near Changi/ Pulau Ubin. (With such a high shipping traffic in our waters, spillage of chemicals and oil is inevitably common.) Floating booms were used then in an attempt to block off the spill. Being moderately soluble (read: much more soluble compared to oil) in water and slightly denser than water, DO NOT expect it to float on the water surface to be corralled by mere floating booms. Phenol will simply dissolve and disperse into the water column, possibly killing many marine organisms along the way. The good news is phenol is reasonably easy to decompose (yes, something toxic to us need not be so to bacteria) so it should be all gone in a few days.

All right, back to our current crude oil spill.

1. Floating boom

Extremely versatile devices. The inflatable types are especially easy to deploy. Other types can be linked together into various lengths to corral or block off an oil spill.

One limitation is of course certain chemicals do not float on the surface for floating boom to work their magic. Another is they do not work so well in rough sea and foul weather. Oil (or other chemicals) can simply be splashed over or pushed under the boom.

Figure: 1 possible type of floating boom

2. Dispersants

Dispersants basically contain detergent, solvent and other stuff. They are supposed to emulsify the oil into tiny oil droplets. Theoretically, this should allow better decomposition.

In the old days, we would be concerned about the toxicity of dispersants on marine life and their persistence in the environment. However, nowadays non-toxic and biodegradable dispersants are in widespread use. Nevertheless, they still have limitations. One: they are not so effective against heavy oils and weathered oils which are too tough to break up. Another common problem is the lack of adequate vehicles (boats, planes, helicopters) to discharge the dispersants, especially for large spills that cover a wide area.

One other concern: the way they work is a double edged sword. Small oil droplets do indeed facilitate decomposition but they also can be taken up by larger organisms more easily. Instead of just floating on the surface, the oil is now "dispersed" downwards where the marine life has nowhere to hide.

3. Skimmers

These are essentially boats fitted with devices to soak up the oil.

Figure: A skimming device dipped into oil. The moving belt is coating with a sorbent material. Upon reaching the rollers, the oil is squeezed out so that the sorbent can container to soak up a new batch of oil.

Figure: Skimming device fitted underneath a boat

Figure: Combination of floating boom and skimmer. The boom is towed between a barge (yellow) and a skimmer (red) which soaks up the oil trapped within the boom.

Figure: A common configuration. 2 barges (yellow) tow a floating boom. The oil collected within the encirclement is removed by a skimmer.

As you probably can guess by now, if the oil spill is huge, you are going to need lots of skimmers (and supporting logistics) to remove it. Similarly, the operation can be hindered by rough sea and foul weather.

However, despite the limitations mentioned, it is still BETTER to clear the oil while it is at sea. Once the oil comes ashore, the problems outlined above will seem like child's play. Labour, time and cost will balloon astronomically if beach cleaning is required.

* All figures are hand drawn by me. Please contact me if you want to use them :-)

What will happen to all this oil? (Oil spill off Changi East)

2010-05-27T02:07:00.000+08:00

Work has been terribly hectic the past few weeks so please excuse me for my lack of posts.

But hearing about the oil spill (2500 tonnes of crude oil) off Changi East made me sit up to find out more. As usual, I depended on Ria's blog posts to bring me up to speed on this accident which is the latest in a string of similar accidents (see list compiled by Siva).

The oil spill has apparently hit our shores despite earlier comments that it might vaporise before reaching land. The argument was being a light crude, the spill could vaporise easily.

So far, I have not seen any mention of exactly what kind of crude we are dealing with. Different crudes will have different compositions, affecting how a spill will behave and the remediation steps required.

Nevertheless, a crude oil should have the following fractions. Only the percentage of each fraction differs for different crudes.

Light fraction
This refers to the low molecular weight compounds e.g. benzene which have a tendency to vaporise. Naturally, their vapours led to the petrochemical odour experienced in the eastern part of Singapore. In terms of marine pollution, these guys are of little consequence.
Water soluble fractionYes, some oily compounds are relatively soluble in water e.g. benzene. These are especially worrisome as they do not float on the sea surface but instead disperse both horizontally and vertically. (You are right if you deduce that living in the depths of the sea does not protect against these dangerous components.)

Being water soluble, they are very bioavailable to marine organisms, easily entering their bodies through inhalation and ingestion. Oil booms have limited effect against them. On the other hand, being bioavailable makes them rather susceptible to decomposition.
Immiscible fraction
These stuff do not mix with water. However, they can form emulsions (suspension of liquid particles in another liquid). Depending on the sea conditions, an oil-in-water emulsion or a water-in-oil emulsion may form.

Oil-in-water emulsion means the oil is distributed into tiny droplets in the sea. This allows them to be more readily decomposed. BUT at the same time, these emulsified oil droplets are quite bioavailable and can disperse vertically, hence they are more likely to affect marine life.

Water-in-oil emulsion commonly appears as yucky patches similar to chocolate mousse. These are tough for microbes to gobble up so they tend to remain in the sea for a long time.
Heavy fraction
High molecular weight stuff like waxes make up this fraction. No surprise here - they are formidable for microbes to handle. They also tend to form "tar balls" - ugly pieces of black, viscous oil. These balls remain unchanged for a long time in the sea.

Moreover, certain heavy compounds are literally that - HEAVY. They sink. Bottom feeders take note as the oil spill is no longer just restricted to the sea surface.

All the above considerations do not make oil spill response any easier. A good response will have to identify the kind of oil it is dealing with, accurately model the transport and fate of the oil and effectively manage adequate resources to combat the spill.

Water quality monitoring (WQM) project in Japan

2010-05-07T09:23:00.001+08:00

Here is another secondary school working on WQM but this is the first one I have seen operating in Japan! WQM aside, it seems our schools are going around the world quite a bit. Environmental projects seem to be a common theme for such overseas trips. And WQM is usually in the forefront of such environmental projects.

School:
I have a challenge here which I hope you may be able to advise. I’ll be bringing a group of students to Japan Kurihara in early June with an objective of doing an investigative project on environmental issue. After much brainstorming, the students would like to do a water quality project. Brings to mind of your course.

With our initiation in the coming trip, we hope our sister school in Japan will be able to follow up with periodic collection of data and hopefully make meaning to the data. We are not sure at this point what kind of data to collect. We can bring along dataloggers and sensors like pH, temperature and dissolved oxygen. But we are uncertain if our sister school will have the equipment to continue collecting such data. Please advise what meaningful data that we can collect and yet not be so imposing on our Japan’s school.

Even without dataloggers, meaningful data can still be collected with regular spot sampling.

Here are some suggestions.

1. pH
Get some universal pH paper which shows reasonable resolution i.e. instead of simply acidic or alkaline, the universal pH paper will measure pH from 1 to 14 based on a colour scale.

2. turbidity
Turbidity in water can be measured using a Secchi disk. In fact, you can get the students to make their own disks. Basically, it is lowered into the water till the disk can no longer be seen. This depth is then recorded.

3. temperature
Easily measured using thermometers though try to get the non-mercury types instead of mercury ones which may break and pollute the water.

4. Settleable solids
This test measures the amount of settleable solids in the water. Strictly speaking, you need to get an Imhoff Cone for the job but I suppose any measuring cylinder will do if the budget is tight.

5. River flowrate
A quick and dirty method is to float an orange downstream within a predetermined distance. Time it and calculate the speed. Better still, estimate the cross-sectional area of the stream and multiply this by the speed to get water flowrate. Besides science, this also tests the math ability of the students.

Of course, if your sister school has the budget, they can procure reasonably priced portable pH meters and conductivity meters (~ S$100 for a low-end one). These will give more precise readings and may be economical over the long term. Digital DO meter tends to be pricier so get one only if they have the budget.

There are also relatively low priced water tests involving chemicals e.g. DO, hardness but depending on the students' ability and the school's budget, these may or may not be suitable.

Good luck!

1-day course on water quality for teachers: My forest is dying and the role of water quality

2010-04-19T13:19:00.003+08:00

Are you thinking of designing an out-of-classroom lesson for your students?

Have you considered water quality monitoring (WQM)? It can be tied to subjects like chemistry, geography and biology. Elements of community service and environmental education may also be incorporated in a WQM session.

There is currently much interest on water from the top (government). Perhaps because of this, much interest has been generated from the base (e.g. schools) too. In recent years, I have observed many projects on water quality, water treatment, wastewater treatment etc. from primary to tertiary level. Some projects were entered for competitions, some became community projects for developing countries while others aim to expose school students to the importance of water and water quality.

WQM involves checking the health of waterways on a regular basis. Whether in natural streams or urban canals, most of the water ends up in our reservoirs which provide our drinking water. Hence, WQM plays a vital role in safeguarding our water supplies.

WQM can become an on-going community service project. For schools in particular, WQM brings students into the field to experience real science and covers the part of their curriculum on environmental education and place based education (PBE).

If you are interested, you can find out more about the fascinating world of WQM in this course. Teachers and MOE staff may sign up for it via Traisi. For more details on the course, click here. Write-up of previous runs may be found here - 1, 2.

Course title: My forest is DYING and the role of water quality
Date: 2 June 2010 (Wed)
Time: 0900 - 1700
Venue: Singapore Polytechnic and in the field

Some further information:
I have regularly performed WQM with my polytechnic students since 2006. My publications include articles in Nature Watch and Nature News. I am currently continuing my WQM work with Nparks and Team Seagrass in Singapore's natural and coastal areas. My training courses (1, 2) on WQM have been regularly attended by students (primary, secondary, JC) and MOE teachers.

The forgotten mangroves at Sungei Pandan

2010-04-06T00:57:00.004+08:00

Talk about mangroves in Singapore and you will hear about places like Sungei Buloh, Pasir Ris, Pulau Ubin and from the savvy ones, Sungei Sembawang, Sungei Punggol, Pulau Tekong. Only from the most experienced naturalists will you pick up whispers of Sungei Pandan. If you look up "Longman atlas: Singapore and the world", you won't even find mangroves there.

There is a very good reason too - Singapore's northern coast is well suited for mangrove building with gentle currents for sediment deposition. Yes, you need to have accumulation of the "yucky muck" for a good substrate. Sungei Pandan mangroves thus appears to be an odd orphan located near the southern coast. Could the conditions at Sg Pandan be similar to those of our northern coast?

I simply can't resist taking my advanced elective module (AEM) class to this interesting habitat for a water quality monitoring (WQM) field trip.

Figure: A massive dam lying right across Sg Pandan. Such dams are common on rivers and canals leading to the sea (Marina Barrage is the big brother among them). They control the loss of fresh water into the sea so that the reservoir (Pandan Reservoir in this case) can be pumped up. Another important function of a dam is to prevent the flow of seawater (read salty water) into the reservoir. Treatment of salty water is expensive since you need reverse osmosis or distillation to do the job. Conventional water treatment does not cut it.

But... (there is always a "but") these dams also disrupts the continuity of the flow, separating the stream into 2 parts with distinct characteristics, one of which being salinity. (1st hint: take note of the vegetation on the bank in the above figure.)

Bad for the aquatic life but great for an outdoor lesson. Here is a Google Earth file compiling the data collected by the participants.

Aside to FMSS students in selected groups: Please use this file to prepare for your case study presentation.

2nd, a dam may prevent precious sediment from reaching downstream. To you, sediment may be muck; to the creatures downstream, it is food, nutrients, home and more. Just as sediment is blocked, the migration of animals for spawning, feeding etc. across the great divide in both directions is also hindered. I am sure environmentalists all over the world have more to say about these dam problems (1, 2; Mekong - 3, 4).

Figure: Steady rain for the whole field trip but what the heck, we are living in the tropics - rain is a standard feature. As long as safety is not compromised (e.g. lightning), some work in the rain is good for the spirit.

Figure: A denizen of the mangroves cleverly avoided the rain by following the guy with the umbrella

Figure: Downstream of the dam. Spot the different root systems of mangrove plants. The exciting mangroves in this figure is a vivid contrast to the boring grasses (no offence to the grass people) upstream.

Figure: Mudskippers surfacing to enjoy the cool rain which keeps their bodies comfortably moist.

Water from the sky... and we are not talking about rain

2010-03-26T23:34:00.001+08:00

I saw this article ‘Sky water' plant a boon for people of Sidlaghatta (The Hindu, 22 Mar 2010) about "a new technology that is reportedly making waves in the U.S. and European countries". Put simply, it is a big condenser that converts the water vapour in the air (aka humidity) into clean liquid water, extremely useful for rural populations with no access to safe water.

Actually, don't you think this is similar to the Dragonfly from our local brand, Hyflux, introduced a few years back? Granted, the Dragonfly is designed for a small family/office (up to 24L per day according to specs) while this sky water plant can crank out 1000L per day, about suitable for a small village. Nevertheless, the operating principles are the same.

Cost wise... sky water costs 10 paise per litre (~ SGD3 per cubic metre (m3), 1 rupee = 100 paise). Our domestic tap water costs SGD1.52 per m3 (including tariff) while newater sold to industry costs SGD1 per m3. (Desalination costs about twice that of the newater process so the price probably follows suit. Based on a ST article in 2004, desalinated water costs SGD0.78/ m3.) No, sky water is not cheap by our standards but when water stands between life and death, any price is cheap.

Incidentally, I do have some concerns about this technology, especially when applied on a large scale, say for a town or (heaven forbid) a city. When you start to draw this large amount of moisture from the atmosphere, what are the effects on the water cycle? Will we have less precipitation which leads to less water for our reservoirs, hence ending up with a zero sum game? Will less moisture in the air lead to larger fluctuations in temperature between day and night since water vapour acts as a buffer in air temperature changes? What will our neighbours say - that we are stealing water from the air which is supposed to pass over them? And I am sure there are many other unintended consequences beyond my imagination.

Figure: Water cycle (from http://cd7.e2bn.net/e2bn/leas/c99/schools/cd7/website/images/bp-watercycle2.jpg)

Though the above scenarios sound far fetched at the moment, they do somewhat mirror the process of drawing groundwater in many countries. An excessive withdrawal will lead to all sorts of problems e.g. sinking land, salt water intrusion, dried up surface soil prone to combustion.

Back to Ngee Ann Stream with Fairfield Methodist School (15 Mar 10)

2010-03-25T21:40:00.002+08:00

This particular field trip for my advanced elective module (AEM), water quality and pollution, was reported in the Straits Times (25 Mar 10).

I have decided to post some exclusive footage not captured in the news article. (Actually, these are just routine photos I take every time I head to the field.) In addition, I have included a Google Earth file compiling all the water quality data gathered by the students on that hot and sunny morning. The students were given hands-on practice on the use of Google Earth as a means of documenting water quality data.

Figure: The 4 sampling stations displayed in Google Earth. Notice the ugly patch of cleared land. More land has since been cleared as Google Earth satellite photos are back dated. See previous post.

Aside to FMSS students in selected groups: Please use the compiled data in the Google Earth file to prepare for your case study presentation.

Figure: Group work at sampling station 2.

The humble umbrella is immensely useful for field work as it can shield one from the rain and sun. (Try recording your data on a rain soaked piece of paper and you will know what I mean.)
The other point to note is the highly turbid (muddy) water caused by sediments being washed down the canal from the nearby construction site. In fact, the turbidity exceeds 1000NTU which is the measurement limit of our turbidimeter (you may check the data here). This has never been observed before in this stretch of water.

Figure: Construction site - clearing of the secondary forest in progress. Note the open ground of easily eroded soil

Figure: Moving on from station 2. The canal floor was still wet from the drizzle earlier in the morning.

Figure: The customary group photo at "Graffiti Bridge" (sampling station 3). Many happy faces despite the "bedraggled" appearance

Push for Singapore students to learn from their environment and that seven-coloured thingy in the sky

2010-03-25T02:10:00.003+08:00

Reading this Straits Times article on "Push for Singapore students to learn from their environment" pushes me to compile some random thoughts and observations into a coherent post.

The article centred on a top institution here espousing the merits of place-based education (PBE), "a learning pedagogy first introduced in the United States". PBE "emphasises learning through real-world experiences, with the local community and environment as a starting point". In short, it connects students to the real world.

Besides the term "PBE", nothing is new. Education has always been trying to get students into the real world, whether through work attachment, community service, field trips, study trips etc. However, in practice, budget and time usually closet the student in the classroom or glue him to the computer screen (online research, lessons, discussion and whatnot). I guess PBE is another repackaging exercise like PBL (problem based learning) a decade back. (Hey, don't they sound similar?!)

Nevertheless, the principles of PBE are highly relevant, so much so that I am a strong believer of PBE despite hearing about "PBE" for the first time. Besides for research purposes, my water quality monitoring (WQM) activities and courses aim to bring students (from primary level all the way to working adults) into the real world environment to experience how it fits (and contradicts) classroom theory and laboratory experiments.

Here are some anecdotes in support of PBE.

I once talked to a JC teacher who accounted that some of her students have never seen a rainbow in Singapore. When they had a field trip to Australia, they were awed by the first rainbow they experienced. Uh... are our students going outdoors nowadays? Not surprisingly, these students have yet to visit Bukit Timah Nature Reserve (BTNR), Sungei Buloh Wetland Reserve (SBWR) and even the highly touted Marina Barrage.

Figure: Marina Barrage in the foreground still under construction in 2007

When I showed my own polytechnic students bug specimens, most of them became instantly fascinated. (Of course, there were always the few who hated and feared bugs.) Why? Throughout their primary and secondary school education, the only bugs they saw were two-dimensional ones on print or screen. They would never have imagined the sizes and shapes of real bugs (albeit as specimens).

Figure: bug specimens

PUB is a strong supporter (financial and otherwise) of water research. A PUB staff once remarked to me about PUB having sponsored a secondary school team in developing a remote mobile WQM device. Indeed a wonderful idea and a handy gadget if successful. Yup, the kind that needs good working knowledge of mechanics and electronics. Shockingly though, the students were unsure of why WQM is necessary and how it is useful to the environment. (Perhaps they have not read this blog.)

Henry Peavy in his book, As if the earth matters, summed the issues up succcintly - one day, students (who will grow into the leaders of the world) can't even recognise a chicken without reading its DNA.

To reiterate my earlier point about students (and adults) not going out into the environment enough (shopping and movies are not counted!), I am perturbed that based on a quick poll of the primary school students in my courses, most use an email account and half write a blog. Looks like learning for them will still remain mostly in the classroom and their computers.

To end, I quote this from the anime, Monster (yes, television and the internet have their place in education but they should be done in moderation) - "education is to develop people useful for society". But anyone who has watched the series knows that these "educated" people ended up as psychological inepts incapable of love. Perhaps a more apt description would be "education is to develop the full potential of an individual - intellectually, physically and emotionally."

Next run of MOE workshop: My forest is DYING and the role of water quality (2 Jun 10)

2010-03-18T14:37:00.000+08:00

This workshop on the theoretical and practical aspects of water quality monitoring in Singapore is scheduled to run on 2 Jun 2010 (Wed).

From my past experiences, I have immensely enjoyed teaching this course and most participants have given encouraging feedback.
Writeup of previous runs may be found here - 1, 2.

MOE teachers and staff may enrol for the course in Traisi.

Before you write off a plant as a weed, read this

2010-03-16T16:28:00.000+08:00

Encouraged by the Celebrating Singapore's BioDiversity blog set up by Ria and gang in tandem with the International Year of Biodiversity 2010, I decided to write about an important but not so cuddly class of living things - plants AND their effects on environmental quality. (They are important not just for their production of oxygen or role as primary producers.)

“What is a weed? A plant whose virtues have not yet been discovered” Ralph Waldo Emerson

“Natural wetland systems have often been described as the ‘earth’s kidneys’ because they filter pollutants from water that flows through on its way to receiving lakes, streams and oceans.” EPA on constructed wetlands

South East Asia is blessed with lush greenery consisting of a vast diversity of plants. Remarkably, this greenery can be utilised in the fight against environmental pollution. Imagine your dish water being piped into a garden of bougainvilleas for treatment before returning to your water closet to flush your waste. Or imagine a plot of industrial land contaminated by a former plating plant being sown with Indian Mustard (Brassica juncea) to suck out the copper from the soil.

The two scenarios above are examples of phytoremediation, a method of cleaning up soil or water using plants. It is an emerging technology attracting significant interest in U.S.A., Canada, Europe and the former U.S.S.R. Though much of phytoremediation is still under research and experiment, many cases of successful application have been documented.

Actually, phytoremediation has been practised by Mother Nature to clean up human and animal waste in wetlands and other water bodies since time immemorial. Phytoremediation as a technology is simply enhancing Nature’s ability to treat soil and water. This element of “naturalness” enables it to be more readily accepted by the public as an environmentally friendly and safe way to clean up pollution.

Not only is phytoremediation environmentally benign, its capital and operating costs are typically low. This makes the technology particularly appealing to developing countries having large polluted areas but limited budgets for cleaning up.

For land contamination, phytoremediation is capable of in situ operation without a need to excavate the entire contaminated site. Unlike traditional pump-and-treat methods, phytoremediation is aesthetically pleasant, having rows and rows of greenery instead of masses of mechanical equipment, hence appearing more like a plantation rather than a wasteland.

The primary disadvantage of phytoremediation is the long time required to effectively clean up pollutants. Operational duration is generally in terms of years. In addition, the depth of contamination should be within reach of the plant roots (choice of plants becomes important).

Phytoremediation may be broadly classified into four different mechanisms - accumulation, degradation, volatilisation and stabilisation.

Accumulation
Most of the work being done on phytoremediation focuses on accumulation, especially in the treatment of heavy metals e.g. lead, chromium, zinc, copper, nickel, cadmium. Certain plants can extract heavy metals from soil or water partly because these heavy metals are chemically similar to the elements required for plant growth and nutrition. The heavy metals are subsequently stored within the plant tissues or on the roots.

Hydroponics systems utilising Indian Mustard were proven effective in removing the above heavy metals. Even radioisotopes such as Caesium-137 and Strontium-90 were successfully removed by Sunflowers (Helianthus annuus). When the plants have matured and reached their accumulation capacity, they are harvested and sent for drying, composting or incineration. The resulting residue still contains the heavy metals hence it has to be appropriately disposed. Many cycles of growth and harvest are necessary before a site is sufficiently cleaned.

Figure: Continuous hydroponics system cultivating Brassica oleracea. Instead of growing vegetables for consumption, can such systems be used to treat wastewater using the same vegetables?

Figure: Phytoremediation experiment using Indian Mustard grown by batch hydroponics in week 4. This was the control which has no heavy metal in the nutrient solution.

Figure: Phytoremediation experiment using Indian Mustard grown by batch hydroponics in week 4. Nickel was present in the nutrient solution. Notice the gradual deterioration of the plant due to the toxic effects of nickel.

Degradation
Degradation is usually applicable to organic contaminants, including domestic wastewater, agricultural wastewater, oil, explosives and solvents. Certain plants are capable of absorbing these organic compounds through their roots and metabolising them into harmless substances.

Usually, these plants receive help from the friendly microorganisms thriving in the rhizosphere (root system zone). The rhizosphere tends to support a large population of bacteria and fungi attracted by the rich environment there. This environment is influenced by root exudates containing proteins, organic acids, alcohols, carbohydrates etc. most of which are beneficial to the microorganisms. Besides exudates, the root system also gives out an important product of photosynthesis – oxygen. Oxygen is particularly useful in promoting aerobic decomposition of the organic contaminants by the surrounding bacteria and fungi into carbon dioxide, water and other harmless chemicals.

Floating plants such as water hyacinth (Eichhornia crassipes), water ferns (Azolia spp.) and duckweeds (Lemna spp., Wolfia spp.) have treated wastewater which is allowed to pass through basins holding these floating plants. More elaborate systems exist in the form of constructed wetlands involving cattails (Typha angustifolia), bulrush (Scirpus spp.), reeds (Phragmites australis), rushes (Juncus spp.) and sedges (Carex spp.). These systems mimic the cleansing ability of natural wetlands and can effectively treat wastewaters of high organic loading e.g. human and agricultural wastewater.

Figure: Basins of water hyacinths in Johor. These can be converted to treat wastewater from domestic or agricultural sources.

Figure: Cattails are common emergent aquatic plants in wetlands (Singapore). They have been incorporated into wetlands to treat organics in wastewater.

Terrestrial plants offer another option as they tend to have more extensive root systems and can potentially grow to larger sizes. Therefore they are able to treat wastewater more efficiently. One example is the Earthship concept by Earthship Biotecture (which designs and builds self-contained houses (Earthships) in the U.S.A. and other countries.

Figure: Outdoors botanical cell next to an Earthship. This cell is used to treat black water.

Their treatment units are designated “botanical cells” occupied by bananas, bougainvilleas, grapes, lemons etc. These botanical cells are either enclosed in greenhouses (integrated with the living quarters) or sited outside next to the house. Grey water from the sink and the shower and black water from the water closet go into separate botanical cells. As black water has a higher organic loading and is a potential biohazard, it detours into a septic tank before heading for the botanical cells.

Figure: Indoors botanical cell. The greenhouse is incorporated into the living quarters. This cell is used to treat grey water.

Volatilisation
Certain toxic contaminants such as mercury and selenium can exist as gaseous compounds. In volatilisation, plants take in mercury and selenium and release them as gaseous compounds into the atmosphere via the leaves. Members of Brassicaceae and cattails (Typha latifolia) have been proven to remove selenium from soil in this manner. Thale cress (Arabidopsis thaliana, Brassicaceae) and Tobacco (Nicotiana tabacum) were genetically modified to incorporate bacterial genes so that they can absorb mercury compounds from the soil and release mercury vapour.

Obviously, the main concern is the fate of the gaseous products – where will these gases ultimately go? After all, volatilisation simply transfers mercury and selenium from soil and water into air. Most experts agree that volatilisation should not be carried out near human populations or under meteorological conditions that do not favour the dispersion of gaseous pollutants.

Stabilisation
Stabilisation is only appropriate for heavy metals in soil. Unlike other mechanisms, it does not remove the contaminants from the environment. Instead, it immobilises the contaminants by root sorption. The plants also provide soil cover to prevent the movement of contaminants via water and wind erosion. Vertical transport of contaminants into groundwater is minimised by controlling the downward movement of water. Ideally, these plants should not transfer heavy metals from their roots to their aerial parts in order to reduce the potential of exposure to humans and animals.

Two cultivars of Colonial Bentgrass (Agrostis tenuis) and one of Red Fescue (Festuca rubra) are commercially available to stabilise lead, copper and zinc in soil.

Stabilisation is usually employed if there is no urgency to clean up a site or the contaminated area is simply too large. Alternatively, it may act as an interim measure before a decision is made on the final method of contaminant removal.

Is this technology for us?

Absolutely.

Even though South East Asia (SEA) lags behind many countries in research and application of phytoremediation, it should not discount phytoremediation as an option to clean up pollution. An inspiration for phytoremediation in SEA is the huge commercial potential as large parcels of land and water are polluted in the wake of SEA countries’ efforts to modernise and develop their economies.

Plants ARE the system in phytoremediation. Before even contemplating whether they can tolerate and clean up contaminated environments, they must be able to grow in that environment. Climate and soil (or water) conditions must favour the plants. All these imply that most studies done in the U.S.A. and other temperate countries cannot apply to the environment in SEA. SEA will have to come up with its own unique phytoremediation solution suitable for its unique conditions.

Wetlands are well known as repositories of biodiversity and pit stops for migratory birds. Constructed wetlands can also perform these functions as documented in many of such systems in U.S.A. Can we incorporate mangrove genera such as Avicennia, Sonneratia or Rhizophora into our very own constructed wetlands to perform wastewater treatment and at the same time provide sanctuary to plants and animals? It certainly warrants research to answer such intriguing questions.

Figure: Abandoned prawn farms in Singapore. These can be adapted as constructed wetlands for phytoremediation.

Figure: Typical mangrove wetlands habitat with Rhizophora sp., Singapore. The potential of Rhizophora for phytoremediation is as yet unclear.

On a more personal level, low impact living is becoming more of a necessity than a lifestyle option. Rural households may be able to implement some form of constructed wetland (albeit closer to the size of a swimming pool), perhaps working in tandem with a septic tank. Water is thus conserved by recycling wastewater back into the house for non-potable uses, effectively closing the loop on water usage.

In closure, phytoremediation is undoubtedly a natural and viable method to treat waste but it is NOT the solution to all environmental problems. It is simply a possible tool in a repertoire of environmental remediation tools.

Water quality in Bukit Timah Nature Reserve (BTNR) - part 2

2010-03-10T17:15:00.000+08:00

Here is an update to my water quality monitoring (WQM) work in BTNR under page 12 of Nature News (Mar - Apr issue).

Figure: Map of BTNR with the locations of the 3 sampling stations - streams cutting across Jungle Fall Path, Seraya Loop, Rock Path

AEM: Water quality and pollution (Mar - Apr 10)

2010-03-10T17:04:00.000+08:00

It always feel good to get into teaching water quality monitoring (WQM) to students. No doubt, you can argue round and round about the benefits to the environment, the next generation, the world etc. but ultimately, the teacher/instructor has to be passionate about what he teaches. If not, all the other reasons do not matter.

Here is the latest batch from Fairfield Methodist School (Secondary).

Figure: Introduction to WQM by having a "field trip" to the nearby fish pond. Notice the student in the foreground wearing slippers. He became the first "casualty" when he slipped into the water. Yes, such things happen, even in a controlled environment like a fish pond.

Figure: Basic data collected on the fish pond. They seem to indicate that the fishes are having a good time in the well maintained pond.

Myth or miracle? - Using 1-cent coins to destroy mosquito eggs

2010-03-04T10:38:00.001+08:00

The following email about using the Singapore 1-cent coin (another version uses the Malaysian equivalent) to stop mosquito breeding has been circulating around. At first glance, this appears unrelated to water quality but read on... and find out another aspect of water quality and macroinvertebrates (bugs) that we seldom think about. (The common theme is about how clean water is indicated by a healthy bug community while polluted water is often dominated by the "uglies" such as leeches, tubifex worms.)

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Subject: How to prevent mosquitoes lay eggs, cheapest way of preventing survival of mosquitoes.

We cannot stop mosquitoes laying eggs at any stagnant water in drains/ponds or water collected in waste pails, tanks, tins, used tyres etc. etc. Of course if you have fish inside the tanks/containers then there should be no problem.

Do you know that there is a very simple and very economical way to destroy the mosquitoes' eggs and not let them hatch into larvae. Very very simple, just put in few 1 cent copper coins into the tanks/containers then it will solve all your problems.. Because in accordance to Japanese Research Scientists, they found the mosquitoes eggs will be destroyed by a kind of mineral discharge from the copper.

DON'T BELIEVE, Try it by yourself and even the small snails also will not visit the containers (with copper coins) collected with stagnant water. You will observe the water collected in the containers will be very clean and clear.
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Should you save up your 1-cent coins to keep the mozzies away? (By the way, production of 1-cent coins has been discontinued some years back due to inflation.) Here's my take:

Certain heavy metals (e.g. copper, lead) have been known to be toxic to bugs and their larvae in water (selected ref: 1, 2). These heavy metals exert their toxicity when they are dissolved in water at concentrations as low as below 1ppm (part per million).

The Singapore 1-cent coin is made of zinc plated over by copper according to the Singapore Mint. Solid copper is barely soluble in water but under certain conditions (e.g. acidity), significant amounts of the copper plating can dissolve into solution. With a sufficient concentration of dissolved copper in water, mosquito larvae (or eggs which are usually more vulnerable) can be killed.

Is the water then safe for drinking? It depends on the final concentration of dissolved copper. WHO (World Health Organisation) provided a maximum limit of 2ppm (2004 guideline) of copper in drinking water. But pouring the water into the sewers should not pose a problem.

Myth or miracle? Neither, it is science. No harm trying but I wouldn't count on this method as my only defence against mosquito breeding.

You can also read my interview on this topic in Lianhe Wanbao (4 Mar 10).

Dear, we have run out of water from the tap. Can you head to the nearest supermarket and loot some? (Earthquake in Chile)

2010-03-02T17:39:00.000+08:00

Different country but same story and ramifications.

Chile was hit by a magnitude 8.8 earthquake on 27 Feb 10, killing at least 700 people by last count. As always, the quest for survival has only started for the survivors. Public utilities like water, gas, electricity and telephone are down. Police presence is barely felt but sorely needed as some parts of the country turn into a looters' paradise.

Imagine a densely populated city like Concepcion (the hardest hit major city) and take away all public utilities. You now have a recipe for social chaos. People become desperate when no water comes out of the tap, the food stalls and supermarkets are closed, no lights to reassure the soul at night, transportation is dysfunctional.... When children get cranky from hunger and thirst, parents are invariably driven nuts.

Cops also face the same challenges and need to take care of their families. It will be lucky if half the police force turns up for work.

Not surprisingly, looting starts and spreads. And the number one items looters look for - water (bottled, packaged, canned), food (bread is a favourite), lighting (candles, torches) and fuel.

Remember, electricity is so ubiquitous in our city lives that if it fails, lots of other systems fail (aka systems built upon other systems in Matrix Reloaded). Even if you want to be law abiding and pay for your groceries, you probably can't do so as the ATMs, NETS (or its equivalent in Chile), cash card and credit card machines are down.

Similarly, even if petrol stations are willing to risk opening for business, their pumps can't work without electricity so your vehicle is only left with whatever gasoline remains in the tank. Therefore, we see footage of looters siphoning fuel from underground storage tanks at petrol kiosks, probably using manual or portable electric pumps.

Throw some opportunistic looters going after electronics and non-essential items in the mix and you have an anarchy brewing.

By the way, the above events are happening just on the second day after the quake. Who knows how ugly the situation will degenerate if utilities remain down for a week, 2 weeks?

One other thing - don't count on your hand phones working either. The base stations or switches may be hit by the earthquake itself or they may have shut down due to the lack of power. Heck, even your own mobile may go "low batt" without a power supply to recharge. (Or are you one of the lucky few to have a crank operated mobile charger? Hint, hint. ) In Chile, the government actually sets up a generator in a public area for people to charge their mobiles. Yes, communications is right at the top of the list, next to water, food and lighting. Another concern is even if the mobile network is all and well, you can expect the network to be jammed in the initial hours after a catastrophe. (This happened right after the Sep 11 terrorist attacks.)

Folks, do keep some supplies at home - water especially, food, candles (torches, batteries), first aid items. If you consume soft drinks, why not reuse the PET bottles to store water instead of dumping them? More environmentally friendly too. If you have empty Lock-and-lock containers lying around, fill them with water. Water is not just for drinking, you still need to wash, bathe, cook and even clear your waste in the W.C.

See my previous post on Haiti for a related discussion.

Water quality monitoring (WQM) projects on the rise?

2010-02-25T20:34:00.002+08:00

It is heartening to see more schools (secondary and pre-U) getting into water quality monitoring (WQM), based on the queries coming in from teaching staff and students. This is especially encouraging given the lack of publicity and media coverage on WQM.

I will truly be happy when I see the same trend in research and innovation funds going into WQM. On the positive side, there is already an observable rise in interest in environmental issues, the most obvious star being climate change with all its implications.

Much money has also been poured into water - not WQM of course but on water and wastewater treatment. In the context of Singapore, this is understandable as water has always been an issue of national security. Wastewater treatment may seem to to be a poor cousin of water supply but it is NOT. Without it, Singapore will likely be infested with filthy waterways and crippled by rampant waterborne diseases. (I suddenly remember this analogous joke about our bottom orifice being the boss among all the other body parts. When it refused to work and shut down (literally), the brain, heart, stomach etc. went into panic and finally acknowledged it as the boss.)

Hopefully, we will start to recognise the role WQM plays in our water supply. Water does not only come from rain dropping into the reservoir directly. It comes from the watershed serving the reservoir. In Singapore's case, the watershed can extend to quite a large area serviced by a network of canals running into the reservoir. Oh well, perhaps one step at a time.

I have copied an excerpt of a recent query below together with my reply. Perhaps some of you may find it useful. (I have of course omitted names of persons and schools in my excerpt.)

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We are a group of 3 students from (omitted) currently preparing to embark on a water quality project by assessing the macroinvertebrates in water body. The two main water bodies we are looking at are WELL stream and a canal in Hort Park.

After looking at your blog, we discovered a lot of useful information that can help us with our project. There are a few problems we hope you can clarify for us.

Firstly, we are unsure about the period needed to monitor the macroinvertebrates in order for the results to be accurate.

Also, we are not very sure about the suitable methodology to monitor the macroinvertebrates as we are strongly discouraged to remove macroinvertebrate from the water bodies. Currently we are thinking about scooping the macroinvertebrates out of the water body to observe, before putting them back since the canal and stream are relatively shallow and the kick-seine method is not practical. The problem with this is that the stream may flow too fast for us to count the macroinvertebrates correctly.

We really want a guidesheet and would like to enquire if you have a guidesheet for identifying macroinvertebrates. Due to short dateline, we would only pick on one species to observe, which we would only decide after going to the actual sites.

-----------------------------

Good to see that you are interested in the bugs in our waters.

A few points from me:

What is your objective of assessing the bugs in your chosen water bodies? Do you have a hypothesis to prove or disprove?

Monitoring period
This depends on your answer to point 1.

E.g. if you are trying to find out the effects of day/night on the bug community, then you probably have sample in the morning, afternoon, evening, after midnight.

Or are you trying to correlate some other parameter to the bug community?

Methodology
This will be tricky if you do not want to remove any bugs from the environment. Sorting and counting will be impossible without bringing the bugs out of the water though I believe it is possible to sort/count on site as your suggested (the bugs will still have to be removed from the water environment).

However, the method you suggested (scoping out and putting back) may not work too well if you do not stir up the bottom sediments. Most bugs are found in the sediment.

Being not familiar with the locations you mentioned, I am not sure why you said that the kick seine method is not practical as it can still be used in shallow waters. Other methods include the Surber sampler, colonisation samplers (leaving something in the water for bugs to colonise) and drift sampler. Colonisation sampling and drift sampling do not require kicking and have a good chance of yielding a signicant number of bugs.

I suggest that you restrict yourself to Order level for identification rather than species level as it is difficult to even go to Family level in the field. A good guidesheet is the Aquatic key sold at Nature Niche. It is designed for Thailand's bugs though it should still work well here. Check if they have stock. If not, you may borrow from me.

Going, going, gone - the end of Ngee Ann Stream (almost)

2010-02-04T18:33:00.001+08:00

In preparation of a coming course on water quality, I went back to my favourite stream for a recce yesterday.

First time I ever saw an excavator clearing debris and aquatic plants from the stream though this should not be surprising. The stream often is muddy and overgrown with Hydrilla. Someone has to maintain and clear the channel for storm water collected in the Bukit Timah area to flow all the way to Pandan Reservoir.

The riparian zone next to the stream in the secondary forest has been completely cleared.

This was taken in 2008, showing the same patch of land (then forested)beyond the railway track.

The riffles are now under a wooden bridge for trucks. Both sides of the stream are not spared.

The riffles as they were in 2009.

Remainder of the secondary forest... waiting to be cleared

Even the belukar was turned into a nice field.

The beluka as it was in 2009.

A large patch of land was already cleared when this satellite photo was taken but even the small sliver of secondary forest (in red outline) bordering the stream is now gone.

I guess the property hunters will soon have another condominium to fight over.

As given in the URA Master Plan 2008, this area is planned for residential purpose.

As for me, I will continue using Ngee Ann Stream as my living classroom though I will have to alter my teaching route and miss out the wonderful shade and undulating terrain of the secondary forest.

Is acidity a problem in streams of Bukit Timah Nature Reserve (BTNR)?

2010-02-02T19:43:00.000+08:00

This is in response to the Straits Times article "Native species in Singapore may be wiped out by acid rain" (14 Sep 09) (I must have somehow missed it last year :-), the reply from Nparks and a recent comment.

BTNR has always held deep memories for me in water quality monitoring as this was where it all started in 2006.

These past few years, the pH of the 3 streams I monitored have indeed been acidic, fluctuating around 3 to 5, with a few instances of 2+ and one instance of 1+ in 2007. Though some websites mentioned that the pH used to be higher in the 1990s, I could find no documentation about this.

The big question is: is this bad for the water inhabitants e.g. crabs, fish? Hard to say. Most literature will insist that such low pH is unthinkable for aquatic lifeforms to thrive or even survive. However, many reports have surfaced about discovering rare and endemic species living in acidic waters with a pH as low as 3. You just need to give living things time to adapt (and evolve?) and they should fit in eventually.

Then the question becomes: has the acidity in BTNR always been like this? We are now back to historical records which are hard to come by.

Nevertheless, here are some possible explanations to the low pH in BTNR (regardless of whether it harms the wildlife there).

Acid rain
From reports, acid rain generally does not lower the water pH below 4. An accomplice maybe but hardly the main perpetrator.
Decomposing vegetation
Ah... this sounds like a more likely culprit. Decomposing vegetation can give rise to humic and tannic acids. These dark brown substances produce the well known black waters in the Amazon and the acidic peat swamps in Sumatra and Borneo. Still, they do not generally cause the pH to go below 3.
Acid mine drainageThis can be a real killer. Sulphur or sulphide bearing ore from underground deposits are somehow brought to the surface and oxidised into sulphuric acid. This CAN really depress the pH to deadly levels.
GeologySimilar to acid mine drainage, certain volcanic streams and lakes (probably having the same origins of sulphur or sulphide in the geology) can push the pH down below 1.
PollutionAnd yes, if you dump acids right into the stream, you can get very high acidity.

1 and 2 appear unlikely in view of the low pH in BTNR. I suppose 5 is out too unless some lunatic is dumping acids at the peak of BTNR.

If BTNR has sulphur or sulphide underground, this certainly is interesting. Has anyone done any geological analysis there?

Then I have a new question if it turns out that the pH used to be higher in the last decade: what has happened that causes the sulphur/sulphide to oxidise into sulphuric acid in this decade?

Till the guys at Nparks and NUS finish their investigation, I guess we just wait and see for the results.

Jungle Fall Path stream

Seraya Loop stream

Rock Path stream

Singapore Bug List

2010-01-29T17:24:00.001+08:00

In response to queries from some readers regarding the types of bugs (macroinvertebrates) found in Singapore's fresh waters, I have compiled a quick list of the bugs I have encountered.

I have broadly classified our fresh water bodies into 3 types:

1. Ponds

Figure: A very stagnant pond next to Sungei Ulu Pandan

Figure: Turbid pond in the forest near Dover MRT station. (Sorry folks, if you intend to visit this one, forget it as the whole area is now under construction.)

Bugs present:

Leeches! And big ones too! These are whoppers compared to the tiny terrestrial ones commonly encountered in Malaysian jungles. I was told that they are Buffalo Leeches (unverified).

There are also tiny ones (fingernail sized).
Dragonfly
Damselfly
Water stick insect
Mayfly
Pond skater
Chironomid ("Bloodworm")
Sludge worm
Beetle

NO Caddisfly!

Unsurprisingly, when the dissolved oxygen (DO) level drops low (say below 2-3mg/L), the ponds become infested with leeches which crowd out the friendly bugs e.g. Mayflies.

2. Streams

Figure: Ngee Ann Stream riffles surrounded by secondary forest then. If you want to visit this wonderful stream, do it soon because the adjacent land is cleared and under construction (yawn, what else is new?). Who knows when the stream will be paved over to make way for yet another condominium?

Figure: Binjai Stream. A good old clear stream PROVIDED rains do not wash sediments into it.

Figure: Tributary into Sungei Pandan. This is a good example of a canal that looks like a natural stream.

Bugs present:

Snail (lots of them in the tributary leading to Sg Pandan)
Collembola
Dragonfly
Damselfly
Eel
Shrimp
Crab (Binjai Stream. Yes, this stream is clean and natural enough to find crabs.)

NO Mayfly! NO Caddisfly!

3. Freshwater reservoir

Figure: MacRitchie Reservoir. Fully exposed to the sky.

Bugs present:

Mayfly
Dragonfly
Damselfly
Chironomid
Shrimp
Snail
Lentil Shrimp
Caddisfly

NO Leech!

Disclaimer: Haha, this is definitely not a complete list. All the above bugs are based on my experience in those waters.

Strangely, NO Plecoptera (Stonefly) and Megaloptera have been found so far in Singapore waters! These 2 orderse are supposed to be really common in other countries e.g. USA, UK.

Acknowledgement: Many thanks to Esther for introducing me to the world of water bugs! I am still learning lots more from her.

One last comment:

Forget about finding bugs in artificial fish ponds with little or no natural substrate - e.g. below

Courses on water quality

2010-01-28T16:59:00.000+08:00

In response to queries about my courses on water quality, I have listed them here for easy reference.

AEM (advanced elective module): Water Quality and Pollution
This 40-hour module is essentially for upper secondary school students as dictated by MOE (unless the school is willing to forgo the MOE subsidy).

Check out this post for more details.
My forest is DYING and the role of water quality
This 1-day course is mainly catered for MOE teachers even though MOE HQ staff have attended it. I was initially told that the course title sounded wacky and school management (the approvers for my customers - teachers) would not be amused with such a title. However, many participants found the title catchy and wanted to learn more about the course. Hence, the title stays as it is.

Check out the course details here.
Water Quality in Natural Habitats
Another 1-day course. This is more suitable for secondary school students and above as it involves laboratory work in addition to the standard (at least for me) field work plus classroom lesson.

Check out the flyer here.
Freshwater quality and biodiversity
Duration of 1 day too. This course is suitable for primary school students and above. There is no laboratory work. Instead, the participants get to see aquatic bugs (macroinvertebrates) up close and personal - an unforgettable experience to most since people in Singapore hardly go out to "play" with nature anymore.

Check out the flyer here.

FAQs on AEMs (advanced elective modules): Water Quality and Pollution

2010-01-28T16:29:00.003+08:00

What are AEMs?
Check out characteristics of AEMs
What are the dates and times?
The teacher in-charge will have to work out the schedule with coordinator of the AEM (typically a Polytechnic lecturer). Each module is 40h so it will take about 5-6 full days either condensed into a week or spread across several weeks.
How many participants are required?
Minimum 20. I normally stick to a maximum of 20 for safety reasons, especially in laboratory and field work.
When must I give you the list of participants?
The name list can be sent to me latest 1 week before the course starts.
What is the cost?
<br>$400 per pax. MOE can subsidise $345 with $55 coming from the student or school.
How do we go about applying for the MOE subsidy?Check out application of funds for running AEMs
Are teacher required to be present?The presence of a teacher is preferred, especially for the field trips.
What is the AEM, Water Quality and Pollution about?Check out my flyer or the description
If I need more information, who can I approach?For further clarifications on policy and implementation issues, please contact:

Water Competitions for Students in Singapore

2010-01-28T15:38:00.006+08:00

I have regularly been asked by school teachers whether Singapore has any competition based on a water theme for their students. That's right, participating (and winning) in competitions are pretty much part of the job scope of our teachers nowadays, from primary right up to tertiary level. Who knows, next time, even our kindergartens are not spared.

These are the few I can think of.

Singapore Junior Water Prize (by Ngee Ann Polytechnic and Lien Foundation)
This project based competition is as close to a water theme as you can get. Registration for 2010 closes on 26 Feb 2010 so hurry! Winners of this Prize will get to compete internationally in the Stockholm Junior Water Prize.
Singapore International Water Festival (SIWF) @ the Barrage (by Singapore Polytechnic and PUB)
This is NOT a project based competition. Instead, it hosts a range of competitions - Environmental Quiz (a, b), Amazing Race, Walking on Water, Solar Boat Race, International Raft Race. The Festival is scheduled for Jun 2010 though the details have yet to be put up.
Green Wave Environmental Care Competition (by Sembawang Shipyard)
Project based. Submission of proposal form closes on 31 Mar 2010. This competition covers more than water as it stretches over many aspects of the environment. Entries need not even be technical since social and educational projects can be accepted.
Singapore Science and Engineering Fair (SSSEF) (by Singapore Science Centre, MOE, A*star)

Project based. It covers a diversity of topics in science, maths and engineering. Winners will represent Singapore to compete at the Intel ISEF (International Science and Engineering Fair).
Weather Station Project Challenge (by Senoko Power Station)
Project based. Related to geography, specifically weather. I am not sure whether this is a yearly competition. There seems to be little information about it.
Singapore Land Authority (SLA) Spatial Challenge
This competition involves the use of GIS (geographic information system). The project obviously has a slant towards geography. The good news is the participants will get to be trained in GIS (a very useful tool - see my earlier post) for free.
Clean Water Challenge (by Singapore Polytechnic School of ABE)
This competition involves the participants building a water filter with given materials on the spot. The winning filter produces the cleanest effluent in the shortest time.
Other inter-school science competitions at cluster or national level (by MOE)

Water lessons from Haiti

2010-01-22T11:58:00.002+08:00

Facing a cascade of news about the situation in Haiti after a magnitude 7 earthquake, I can't help but compare Haiti with Singapore. (I know this sounds off topic but don't worry, I will get to the water part soon.)

First, a summary of the aftermath in Haiti:

100000 - 200000 people died (the number varies, depending on the news source)
Survivors are in dire straits - severe lack of food, water and shelter.
The various institutions (government, law enforcement, health care etc.) are seriously crippled.
Looting is rampant in the capital.

Some recent news of Haiti:
HAITI: Agencies rush to get water to earthquake disaster zone (19/01/10)
Haiti's Environment Needs Long-Term Help: Experts

Most of us would immediately sympathise with the Haitians. But if asked whether the same thing can happen in Singapore, most of us will instinctively shake off such a possibility.

Here is an informative post discussing the possbility of an earthquake here. Naturally, there is no definite answer since earthquake prediction is not an exact science though our odds of not having an earthquake seem pretty good.

However, I remember reading a book in my childhood about an earthquake recorded in Singapore in Feb 1861. The interesting part is not the earthquake but the rain of frogs and fishes that preceded the earthquake. See:

However, there was no mention of casulties, magnitude of quake or damage level. I presume that was linked to the quake in Sumatra at that time.

My point is: Singapore's history is so short that we won't know if there ever was a killer quake in the past while we assume we are safe.

Anyway, it does not take an earthquake to disrupt civilised society. You can choose from any of the following crises (some more probable than others):

Terrorist attack
Tsunami
Nuclear power plant accident

Indonesia - a, b (is Indonesia still building its nuclear plant in Java?)
Malaysia
Singapore

Social unrest
Economic collapse
Pandemic (H1N1, H5N1, Sars etc.)
20 December 2012 (this will be hard to survive)

Back to water...

It is said that you can only live 3 days without water yet how many of us actually pause to ponder about how the water reaches our taps and where to get water if our taps run dry? From Haiti's experience, water is clearly a top priority commodity once the normal channels of water supply are disrupted. Yes, I am sure people will kill to obtain this precious fluid.

Check out the following sites on handling a crisis/ emergency in Singapore.
Singapore Government Crisis News Website
Water distribution (under purview of SCDF)
Stockpiling of essential household items (SCDF)

We are encouraged to stockpile food, candles, first aid items, torches, radios but water is glaringly missing from the list. (Do not be mistaken. The above items are critical too.) Instead, in an emergency, water is to be collected at distribution points served presumably by water tankers. How reliable is this? If 10% of the population is incapacitated, will the water tankers still run? What about 50% of the population being incapacitated?

It is my belief that each family should stockpile some water. How much? This is trickier to answer. A good estimate is to have 8 litres per person per day to survive comfortably. Depending on the severity of the crisis, you may need to store enough water for 3 days to 3 years but I feel 3 days should be the bare minimum.

Alternatively, your water supply may still operate but because of disruption to the water treatment process due to the crisis, the water quality of water from your tap is less than ideal. (In fact, some people already believe this to be so currently, which explains the popularity of water filtration/ purification devices.) Do you have the ability to filter/ purify your water? If you are lucky to have a water filter/ purifier, does it need electricity (which may not be available) to work? If you boil your water, is gas or electricity available?

Figure: My favourite Katadyn Mini - mostly for use outdoors. It can remove particulates and most bugs but not heavy metals, pesticides. However, because it is so light and small, I won't mind bringing it along whenever I head outdoors so when I really need it, it will be there. (Batteries are of course not needed.)

A final question to keep you thinking critically - if there is no water supply, your toilet flush is not going to work. What are you going to do with the loads of bodily waste from your family - both liquid and solid. Talk about solving a filthy problem.

I hope that at the very least, this post will start you thinking about the many things we take for granted in civilised society and how fragile many of society's support services are. And if you go ahead to do something about these, all the better.

Fish kill at Pais Ris: do you have a million bucks to spare?

2010-01-14T15:24:00.004+08:00

Apparently, the recent fish kill at Pasir Ris (Dec 09) and Pulau Ubin (Jan 10) was not the only event concerning negative water quality in that area.

Other events include:

2008, 2009 - Pasir Ris Beach was found unsuitable for swimming because of the high bacateria (Enterococcus) count
Dec 2006/ Jan 2007 - mass death of marine creatures in Chek Jawa due to drop in salinity caused by heavy rainfall
(Update: a comment from "Death Note from Chek Jawa" recorded the salinity at 22ppt (parts per thousand). I believe this was measured using a portable conductivity meter. I personally find measuring the salinity this way can be rather confusing to readers as the salinity is calculated by the meter based on the conductivity multiplied by a conversion factor. Unfortunately, this conversion factor can be quite different for different waters, ranging from 0.5 to 0.7. Hence, I personally find it more useful to report the salinity as the base measurement of electrical conductivity adjusted to 25oC.)

According to AVA, a monitoring programme has already been in place to test the water quality in the said area. Without elaboration from AVA about its programme, I shall not comment on its effectiveness but here are my suggestions for AVA/NEA for a price tag of (you got it!) a million bucks.

Since this Pasir Ris/ Pulau Ubin/ Changi is such a problematic area in terms of water quality, install a continuous monitoring system with maybe 3 to 5 monitoring stations to provide real time data for immediate response. The technology is there... you just need money. Even manpower is saved since staff only go down to the field for further investigation or to do sampling for a more detailed analysis.

3 - 5 buoys containing water quality and metereological sensors, telemetry package, solar panels and batteries. See previous post. They should be strategically placed for maximum monitoring effectiveness - 1 at north of Pulau Tekong, 1 south of P. Tekong, 1 between P. Tekong and P. Ubin, 1 north of P. Punggol and 1 north of Pasir Ris Beach
One/two water quality sensor packages installed on each buoy. See previous post. They should be able to measure depth, dissolved oxygen (DO), turbidity, electrical conductivity (EC), temperature, pH, chlorophyll, nitrate, ammonia. I was told that each package can cost about S$15000.
Remote server (perhaps in the agency's HQ) with the capability to receive data via cellular signals from the buoys/sensors.
To handle these vast amount of water quality data, GIS (geographic information system) should be installed on a workstation linked to the remote server to document and analyse the data. See previous post. A GIS can also provide a visual display of the water quality with colour coding. Any unusual or out-of-spec event should trigger an alarm.
Better still, install a modelling software to tie in with the GIS. Some free models can be found at USEPA. A properly calibrated model can make predictions and simulations on the water quality in the area to prepare for future events of similar or worse magnitude.
Qualified and trained manpower to use and maintain all the above goodies.

All the above may not even amount to $1M. I am sure this system will reduce the guesswork involved in future events e.g. whose fault? and probably allow for rapid remediation if required.

Some thoughts on the fish kill at Pasir Ris

2010-01-14T12:41:00.001+08:00

I must admit I have not been following the news about the recent fish kill at Pasir Ris as close as I should have. But thanks to Ria, her blog posts quickly brought me up to speed on the sequence of events. Here are the links with further links inside the webpages.

From all accounts, the situation appeared to be a classic case of eutrophication. Put simply, eutrophication is an excessive growth of algae (sometimes, the term plankton is used though they are not the same) caused by the introduction of nutrients into an ecosystem. Depending on the type of algae, the nutrients may be nitrate, phosphate, silica or others.

Without further information from AVA (or NEA which was strangely silent in this whole episode) about the kind of algae (or "plankton" as given in the media) in the seas off Pasir Ris, I can only surmise that nitrate and ammonia (which can degrade to nitrate) are the probably culprits. In general, seawater is limited by nitrogen so once a sudden excessive input of nitrogen (in the form of nitrate or ammonia) rushes in, the algae immediately makes the best of this bonanza to multiply.

Nitrate is commonly found in fertilisers (yes, it is good for plants too!) and sewage (an decomposition product of ammonia). The question is: who was releasing these fertilisers or sewage? One suggestion was the incidental heavy rains have washed fertilisers or sewage into the sea. Of course, the question remains: where did these fertilisers and sewage come from?

Algae grows fast but they die fast too. Dead algae is major bad news as they decompose, using up dissolved oxygen (DO) in the water. Since many marine organims can only breathe DO, they are in trouble. However, marine organisms are not created equally. Some are more hardy than others since they need less DO to survive.

Wouldn't oxygen from the air replenish the loss of DO in seawater? Yes, it would but the rate of replenishment lags far behind the rate of DO usage in decompostion. Imagine lots and lots of algae dying and taking up DO. Atmospheric oxygen wouldn't have a chance!

Figure: Eutrophication at Botanic Garden (Nov 08). The greenish water is a dead giveaway.
Monitoring by AVA
According to AVA, regular monitoring was in place even before the recent fish kill event (Straits Times Forum 11 Jan 10). When the fish kill occurred, its staff was monitoring daily.

It will be great if AVA can reveal more about its regular monitoring programme - how regular? where are the monitoring stations? What kind of data are collected? For its daily monitoring during the fish kill episode, in addition to the above questions, can AVA reveal the following - what kind of algae was detected in the bloom? Was there a spike in the nutrient levels? What kind of nutrients? What is the trend for DO during the monitoring period?

What about NEA? It has many water sampling stations along the coast. Can their data shed any light on the fish kill? For that matter, NEA has never elaborated on its monitoring programme either i.e. kind of data collected, frequency of collection. Its water quality results have never been in the public domain (except for bits and pieces in its annual report.) (That goes the same for PUB. Have you ever tried requesting for a copy of the analysis report of the tap water that goes to your house?)

Figure: NEA sampling stations in both inland and coastal waters (taken from NEA website a few years back as it no longer could be found currently)

For some reason, water quality data are considered confidential in Singapore. Do such data constitute an issue of national security? Or are the agencies concerned about a vulnerability in their legal position?

Check out the extensive data placed online by the Environmental Protection Department (EPD) of Hong Kong.

Or the data compiled by USGS (U.S. Geological Survey) for the USA.