Saving our shores and water
Prof Liu believes that we need to be prepared for the worst with rising sea levels
Thanks to climate change, we can expect moremassive erosion, land sinking, as well as soil and water contamination as rising seawaters intrude inland. Besides more severe drought, there could be serious flooding in Singapore, especially with the heavy rainfall inland and the strong winds from the South China Sea blowing in tandem. These winds push the waves towards the shore and cause seawaters to pile up along coastlines, overwhelming coastal defences as they surge inland, explained Professor Philip Liu, Distinguished Professor with NUS Engineering, internationally recognised for his research in coastal oceanography and an expert on coastal hazards.
Having more coastal reservoirs is a good idea to catch storm water runoff, said Prof Liu, but these reservoirs also need to be protected from rising seas. Coastal defences such as sea walls, tidal gates and dykes would need to be adjusted according to projected sea level rises. To help with more accurate projections, Prof Liu and a team at the NUS Tropical Marine Science Institute (TMSI) have downscaled a global climate change model into a Singapore model, coupling this with water runoff and storm surge models in a new initiative. With these models, engineers can then look at specific scenarios and develop toolboxes to help city planners design infrastructures and solutions, said Prof Liu.
“We need to be prepared for the worst scenario. In bigger countries, the city can move further inland. But in Singapore, this would mean encroaching on our nature reserves. If we clear our forests, we are going to get less rainfall and that would further affect our water supply,” he commented.
Towards a circular economy
In responding to water challenges, a holistic approach is needed, said Professor Hu Jiangyong, Director of Centre for Water Research (CWR) at NUS Civil and Environmental Engineering (CEE). “We need to develop an approach based on the principle of circular economy which maximises the utility of limited resources while minimising the production of waste. In the past, our main emphasis was to develop new methods of treating used water to produce good quality water. Now, we are also focusing on the need to recover valuable resources from used water,” said Prof Hu.
Their efforts towards a circular economy have borne fruit and they have been reaping accolades. For example, Professors Ng How Yong and Ong Say Leong from CWR have come out with a novel system to harvest biodiesel — a form of sustainable energy — from used water. This project won first prize at the third GCL Cup of the International College Green Energy Technology Innovation and Entrepreneurship Competition in 2017.
In collaboration with Prof Ong, Prof Hu has also developed a novel bioretention system for sustainable stormwater management which makes use of waste materials such as water treatment residues as additives in soil media. This technology has been featured in PUB’s ABC Waters Design Guidelines which provides guidance to industry professionals on implementing environmentally sustainable green features in their developments.
Another project known as EWat by Dr Olivier Lefebvre, won the IES Prestigious Engineering Achievement Award 2019 at the World Engineers Summit in August. Targeting hard-to-treat industrial water, it is able to remove up to 99 per cent of impurities without producing any secondary waste, said Dr Lefebvre who has worked with industries such as chemical, electronics and farms, which produce very challenging wastewaters and sludge.
With emerging contaminants such as pharmaceuticals, pesticides and residues from a wide range of personal care and common everyday products finding their way into our water these days, Prof Hu and her team are also paying a lot of attention to this area of treatment. Working with French researchers, they have successfully turned biomass such as cut tree branches and leaves into activated carbon for removing emerging contaminants. They have also developed a novel ultraviolet advanced oxidation process (UV-AOP) to generate highly efficient oxidants for breaking down emerging organic contaminants. A pilot-testing system is in the works to further testbed and evaluate its long term performance.
Protecting our waters
Recently back from a World Health Organisation (WHO) and Food and Agricultural Organisation (FAO) Expert panel meeting in Geneva, Associate Professor Karina Gin, who leads a research team in water quality at CEE, said that a big concern is how climate change impacts the water that goes into our food chain — from agriculture to the juice we drink. Clearly, our source water needs to be protected. A risk assessment needs to be built, identifying the hazards and evaluating the risks with control measures developed.
The team has been compiling a “hit list” of water-borne pathogens and indicators and tracking their occurrence in environmental waters. With climate change, not only are we seeing more algal blooms but also an increase in toxic species, said Assoc Prof Gin. Her team has been characterising and tracking local species of cyanobacteria which are capable of producing nasty toxins and nuisance off-flavours. Working with Shanghai Jiao Tong University, they are sequencing cyanobacteria in Singapore and China, with the aim to develop a model cum genomic database to assist in algal bloom management and protection of water resources.
They are also developing natural methods such as using viruses (cyanophages) to kill algae, and using bacteria to breakdown algal toxins. Such methods are more environmentally friendly compared to the use of chemicals like copper sulphate which is toxic.
“Compared to five years ago, we can identify the culprits creating toxins in our waters more accurately and swiftly using next generation sequencing (NGS) technologies. Previously, microbes were identified using culture-based methods which besides being labour intensive, also took ages to yield results. Then, molecular based methods such as quantitative polymerase chain reaction allowed detection of specific microbes within two hours. Now, there are new in situ NGS instruments which can give real-time snapshots of the microbial community in a water sample, although these still require some validation and research when applied to different environmental waters,” said Assoc Prof Gin.
The challenge remains for the team to design real-time detectors which are more sensitive and accurate, as well as able to detect the different species present in the microbial community, including strain variants capable of mutating, especially in the face of global warming and climate change.
Sustainability, not just a catchword
Fighting climate change goes beyond safeguarding our shores and water, of course. “We would all need to be united in our efforts. It should not be just activists taking to the streets. We need to internalise it,” said Professor Philip Liu.
“When I went to a conference in Jakarta recently, I was informed to bring my own tumbler as paper cups would not be provided! I thought that was great,” he said, adding that we could do away with serving plastic bottles of water at conferences and events. We can also cut down our use of electricity for example — and step up our ideas on water recycling.
On this front, Dr Olivier Lefebvre shared some green aspects of his current work — an adaptation of EWat which couples electricity with sunlight. He envisions that the system could be downscaled and used in households.
“Your pail of dirty, grey water after mopping the floor or cleaning dishes could be recycled into clear water using this device. After a few minutes, voila, you could use the water again for other purposes,” he said.
How nifty is that.