Researchers at the National University of Singapore presented an innovation that could remove up to 99 % recalcitrant impurities from industrial wastewater without using chemicals or generating sludge.
Singapore — A team of scientists from the National University of Singapore (NUS) has come up with a novel approach to treat industrial wastewater using electricity as a reagent for purification. The method can remove up to 99 % of hard-to-treat organic compounds found in various types of industrial wastewater. The NUS-developed system operates on low electrical power and does not generate secondary waste, such as sludge, that requires further costly residual waste processing such as incineration.
“Our electrochemical system has shown that it can achieve complete mineralisation of any organic pollutant. This means the system can completely remove organic compounds in the wastewater by degrading them into water and carbon dioxide. This novel system can also be incorporated as a pre-treatment to an existing wastewater treatment scheme. It operates on low electrical power and the system could easily be combined with solar power and other purification methods such as using membranes and biological treatments,” explained Assistant Professor Olivier Lefebvre from the Department of Civil and Environmental Engineering at NUS Faculty of Engineering, who is the leader of the research team.
Removing Organic Impurities
The system developed by the NUS scientists uses electrochemistry to treat water and wastewater and does not require chemicals to be physically added into the system.
The treatment begins with the pumping of wastewater into the system’s chamber. As electric current is passed, electrodes in the chamber generate hydrogen peroxide and hydroxyl radical (one of the most powerful oxidising agents) that will react with the complex organic compounds in the water. The generated hydrogen peroxide and hydroxyl radical are completely used up during the treatment and they continuously break down the complex compounds into simpler molecules, until all organic contaminants have been degraded into water and carbon dioxide.
Cost-effective Alternative for Wastewater Treatment
Besides benefitting farmland, electronics and pharmaceutical industries, the new electrochemical system developed by the NUS team could potentially be utilised by heavy manufacturing industries that require ultrapure water for their processes such as mining, oil and gas, and textile industries; and the shipping industry for the disinfection of problematic ballast water from ships. It could also be applied to treat micro pollutants in domestic wastewater as well as manage water purity in various outdoor environment such as in controlling algal growth in water bodies and purifying landfill leachate.
Next Steps in Research
Asst Prof Lefebvre and his team have applied for two patents for the technology used in the electrochemical system and they are now testing the system on more types of industrial wastewater to further refine the design and optimise the efficiency of the system. In addition, the team has recently developed superior graphene electrodes that can speed up the system’s water purification process. They are also looking to collaborate with industry partners to commercialise the technology.