Issue 160, July 2016
Reducing energy needed in wastewater treatment
​New nanofilters invented use five times less energy than current reverse osmosis process

Scientists at Nanyang Technological University (NTU 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 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. This high water pressure, typically 10 bars and above, means that the water pumps need a lot of energy.

However, NTU’s proprietary nanofiltration (NF) hollow fibre membrane does away with both ultrafiltration and reverse osmosis, combining the two processes. It also requires only two bars of water pressure, similar to the pressure found in a typical home pressure cooker, to filter out the same type of contaminants. Yet it produces water that is almost as pure as through reverse osmosis. 

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

De.Mem which owns over a dozen water treatment plants in Vietnam and Singapore, will be building a pilot production plant in Singapore to manufacture the new membranes.

© Nanyang Technological University Singapore