A new type of nanofilter could reduce the energy needed to treat wastewater by up to five times, by combining ultrafiltration and reverse osmosis, and reducing the pressure required during the process.
A team at Nanyang Technological University (NTU Singapore) has invented the new nanofiltration hollow fibre membrane, which only requires two bars of water pressure.
Comparatively speaking, conventional water purification processes in wastewater treatment, requires high water pressure, typically ten bars and above. This is because water is passed through an ultrafiltration membrane, which filters out small particles, before a reverse osmosis membrane is used.
In reverse osmosis, water is pushed through an extremely fine membrane at high pressure to separate water molecules from any remaining contaminants which are tiny – about a thousand times smaller than the width of a human hair, such as salt, heavy metals and toxic chemicals like benzene.
The new filter, despite operating at much lower pressures, can produce water that is almost as pure as that which has gone through a reverse osmosis process. NTU's Nanyang Environment and Water Research Institute (NEWRI) took two years to develop this technology, and it is now being commercialised by a spin-off company called De.Mem.
De.Mem owns over a dozen water treatment plants in Vietnam and Singapore, and will build a pilot production plant in Singapore to manufacture the new membranes.
The company will test the new membrane modules in real world usage in its plants to verify its effectiveness and efficiency before scaling up to a full industrial production line.
According to Professor Ng Wun Jern, the executive director of NEWRI, the new technology will help growing cities and communities meet the burgeoning demand for clean water and wastewater treatment.
"If we are to address the ever increasing demand for clean water, what the world needs are innovative technologies like NTU’s new nanofiltration hollow fibre membrane that allow us to treat and produce extremely clean water at a low cost, yet have high reliability and are easy to maintain," he said.
The new nanofilters are designed for commercial scale-up and production, being easy to manufacture using low-cost chemicals that are up to 30 times cheaper than conventional chemicals, making them suited for mass production.