Thursday, December 22, 2011

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

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.

Friday, December 16, 2011

Water quality monitoring (WQM) workshop for Sengkang Floating Wetland

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

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,


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

Tuesday, November 01, 2011

Water quality monitoring (WQM) workshop for Sengkang Floating Wetland

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!

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
Tel no : 6731 3274

Monday, October 03, 2011

Water quality monitoring workshop for CUGE

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 > 04 Oct 2011 - A Fun and Enriching Hands-on Experience Sampling and Testing Water

Friday, August 05, 2011

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

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):

 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.

Wednesday, August 03, 2011

Testing your drinking water - the whys and why nots

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.

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.

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

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.

Tuesday, July 26, 2011

Phytoremediation Question

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,


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.


Saturday, July 23, 2011

How to get rid of your seemingly unstoppable pond algae

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.

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

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.

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.

Friday, July 01, 2011

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

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...

Thursday, April 28, 2011

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

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.

Monday, April 18, 2011

Some random thoughts on floods and water quality

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) ( 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.

Monday, April 11, 2011

Answering a simple question - what is water quality?

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.

Thursday, April 07, 2011

Latest wetland craze - Lorong Halus Wetland

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.)

Wednesday, March 02, 2011

Outdoors classroom - Ngee Ann Stream

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