Source: Sarp Saydam/UNSW Science

Scientists at UNSW have developed a graphene-based, laboratory-scale filter that is capable of removing over 99 percent of the natural organic matter that lingers after the traditional treatment of drinking water.

"Our advance is to use filters based on graphene — an extremely thin form of carbon. No other filtration method has come close to removing 99 percent of natural organic matter from water at low pressure," said Dr. Rakesh Joshi of the UNSW School of Materials Science and Engineering.

"Our results indicate that graphene-based membranes could be converted into an alternative new option that could in the future be retrofitted in conventional water treatment plants."

Concerned that the lingering natural organic matter can impact the success of direct filtration plants (often reducing their capacity after a heavy rain), the team of scientists, working alongside Sydney Water, set out to test the new approach on treated water from the Nepean Water Filtration Plant in western Sydney.

"The most common methods used at present to remove organic matter from water supplies include the application of chemical coagulants," said Dr. Heriberto Bustamante of Sydney Water.

"However, these existing treatments are only partly effective, particularly as the concentration of natural organic matter is increasing."

Dr. Joshi said: "The new treatment system is made by converting naturally occurring graphite into graphene oxide membranes that allow high water flow at atmospheric pressure while removing virtually all of the organic matter."

The findings are detailed in the journal Carbon.