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NTU scientists develop energy-saving nanofilter for wastewater treatment

Scientists at Nanyang Technological University (NTU) in Singapore have invented a new type of nanofilter that could reduce the energy needed to treat wastewater by up to five times.

Typically, for the last steps of water purification in a wastewater treatment process, an ultrafiltration (UF) membrane filters out small particles before a reverse osmosis (RO) membrane is used.

In reverse osmosis, water is pushed through an extremely fine membrane at high pressure to separate water molecules from any remaining tiny contaminants.

These unwelcome particles are about a thousand times smaller than the width of a human hair, including salt, heavy metals, and toxic chemicals like benzene.

The used high water pressure, typically 10 bars and above, means that the water pumps need a lot of energy, but NTU’s proprietary nanofiltration (NF) hollow fibre membrane does away with both ultrafiltration and reverse osmosis, combining the two processes.

The membrane also requires only 2 bars of water pressure to filter out the same type of contaminants while producing water that is nearly as pure as through reverse osmosis. 

Developing the technology took NTU's Nanyang Environment and Water Research Institute (NEWRI) about two years and it is now being commercialised by an NTU spin-off company De.Mem.

De.Mem owns over a dozen water treatment plants in Vietnam and Singapore and it will build a pilot production plant in Singapore to manufacture the new membranes.

NTU Professor Ng Wun Jern, the executive director of NEWRI, said the new technology marks “yet another huge step forward” for Singapore, as it will be the first of its kind to hit the market. 

“With the increasing urbanisation of cities and fast growing global population, more cities and communities will face an unprecedented challenge to meet its growing demand for clean water and wastewater treatment,” Ng said.

“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.”

NTU Professor Wang Rong, the director of NEWRI’s Singapore Membrane Technology Centre and who led the team in designing the new NF membrane, said they had designed it for commercial scale-up and production.

“Our new membrane is easy to manufacture using low-cost chemicals that are 30 times cheaper than conventional chemicals, making it suitable for mass production,” explained Wang.

De.Mem will test the new membrane modules in real world usage in its plants to verify their effectiveness and efficiency before scaling up to a full industrial production line.