Australian researchers have developed a filter which promises to revolutionize how we treat drinking water.
Graphene has been making many appearances in science lately, owing to its unique physical properties. Today, it's making headlines in a rather unexpected field of research: water treatment. Researchers from the University of New South Wales (UNSW) Sydney, working together with Sydney Water, have created a world-first graphene filter that can remove 99% of the natural, organic matter left behind by conventional treatment of drinking water. The team is now working on scaling up their technology.
Sydney Water caters to the H2O needs of about 4.8 million people throughout Sydney proper, the Illawarra, and the Blue Mountains. One problem they're facing is that the source of this water (nature) doesn't do a very good job at keeping the water pure. For that, Sydney Water employs direct filtration plants, but there's still a problem -- during periods of heavy rains, small-particle organic matter contaminants negatively impact the performance of these plants, reducing their overall capacity.
No organics allowed
The most common working principle these plants rely on is the use of chemical coagulants, which fuse all the organic material together into goop that settles on the bottom. High enough concentrations of these contaminants interfere with the chemical reactions that produce said goop, meaning the plants need to reduce output to ensure the water's purity.
The team, led by Dr. Rakesh Joshi of the UNSW, decided to skip the chemicals altogether and rely on good old-fashioned mechanical methods:
"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% of natural organic matter from water at low pressure," said lead researcher Dr Rakesh Joshi.
"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."
The filters are produced by converting natural graphite into membranes of graphite oxide. At high pressures, these membranes become selectively permeable, allowing water to flow through, but not contaminants.
Currently, the filters have only been used in a prototype, small-scale form inside laboratory settings. However, given the exciting results they've had thus far, the UNSW team plans to upgrade the experimental rig to a small pilot plant for field testing.
While water filters don't seem like headline news, it all has to be viewed in the context of our present situation. Pollution, especially plastic pollution, has been plaguing our waterways for decades now. We're pumping out a lot of waste into the waterways around us, and it's not going away as we hoped or wanted to think. There's even cocaine in there. In later years, the situation has taken a dramatic turn for the worst. Plastic particles have found their way into the water we drink, and it also bears the industrial legacy of toxic metal contamination.
Better water filters could help stop the goop before it ever enters the waters -- and until it's clean again, they will help keep the goop (and plastic) out of our bodies.
The paper "Application of graphene oxide membranes for removal of natural organic matter from water" has been published in the journal Carbon.