Friday, March 26, 2010

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

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.

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.

Thursday, March 25, 2010

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

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

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."

Thursday, March 18, 2010

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

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.

Tuesday, March 16, 2010

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

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.

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 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.

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 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?


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.

Wednesday, March 10, 2010

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

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)

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.

Thursday, March 04, 2010

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

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.)

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.

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).

Tuesday, March 02, 2010

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

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.