It may now be finally be possible to filter pure drinking wastewater through an innovative wastewater treatment process. Researchers from Australia and Russia have found a novel way of using graphene as a cost-effective way to eliminate toxins and bacteria from wastewater resulting in drinkable water regardless of the initial wastewater quality.
But what is graphene and why is it a more effective wastewater treatment process than traditional systems? Graphene is a special form of carbon that is just one atom thick. It is so thin that it is fundamentally considered two dimensional.
Researchers from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia have explored the use of graphene in water filtration and have developed an extremely efficient system that is both simpler and quicker than other filtration methods.
The scientists have long known that graphene can be multiple orders of magnitude better in water filtration than industry-standard reverse osmosis membranes. This is because graphene is comprised of extremely narrow channels which can filter out larger molecules of toxic substances resulting in a yield of pure water. It is such an effective system that even the introduction of acidic and alkalotic water sources resulted in a neutral pH water output.
They developed a special form of graphene called ‘Graph Air’ which is a single step system that can effectively produce drinking water from extremely polluted water using heat, the Graph Air membrane filter, and a water pump.
Another significant advantage of using graphene filters is that is not prone to fouling, a phenomenon known to occur frequently in most conventional systems. Fouling is the build-up of pollutants on a membrane filter that reduces its effectiveness unless it is periodically cleaned. Graph Air was shown to operate at full capacity without succumbing to fouling.
The CSIRO researchers have discovered a more cost-effective way of producing graphene without having to go through the more intricate and resource-intensive production method. They used a process called the ‘ambient air vapor deposition process’ which is faster and more eco-friendly because it does not require the use of expensive volatile gases. The researchers managed this by using a cheap and renewable material to produce their graphene: soybean oil.
They integrated Graph Air in a membrane distillation (MD) system which is a heat-powered water purification method that effectively filters seawater and industrial waste. MD uses a vapor pressure gradient that runs across a hydrophobic membrane. The water then goes through parallel flows of a ‘hot’ feed side and a ‘cold’ permeate side, resulting in purified water vapor forming on the feed side.
Salinity has been the biggest obstacles in producing purified water. But the Graph Air MD system is capable of removing the salt from any water source regardless of salinity and has shown durability and resistance to fouling making it an excellent wastewater treatment process.
In Russia, graphene has also been used to treat wastewater but in a different way. Researchers from Russia’sNational University of Science and Technology (MISiS) showed that graphene could purify water without the need for chlorination.
In their study, scientists eliminated E. coli from a solution by injecting it with a graphene oxide saline solution. The team found that the injected graphene could capture toxic bacteria by forming flakes around it. The flakes were then removed to produce drinkable water and the graphene by-product was then reused. The scientists believe that the graphene oxide works because it develops free radicals that are toxic to bacteria.
The researchers are confident that this purification system would eliminate the need for chlorination. Its low-cost and scalability also makes the graphene oxide system easily applicable in large wastewater treatment facilities.
If you are a municipality in Ontario and in need of a biosolids management solution, please feel free to contact us at 1 (877) 479-1388.