Currently, there are 2 billion people with inadequate sanitation and 80% of wastewater globally is discharged into our environment untreated. The pollution causes environmental damage, disease and financial burden upon small businesses, severely affecting communities’ ability to prosper.
We currently heavily rely on centralised sewage networks which are expensive to install and energy intensive. With a new approach focusing on a circular decentralised model, we can treat waste onsite and recover energy. Anaerobic Digestion (AD) is one method of recovering energy from waste; however, digesters are large, have long treatment times and require careful operation. Electro-Methanogenesis is an emerging technology that increases energy production, reduces treatment time and increases the stability of the AD.
Electro-Methanogenesis is the direct biological conversion of electrical current, hydrogen ions and carbon dioxide to methane in an Electro-Methanogenic Reactor (EMR). A small voltage (<-0.8 V) is applied to the electrodes. Wastewater containing organic matter is broken down into CO2 and hydrogen ions by electroactive microorganisms hosted on an anode. The electrical current creates hydrogen at the cathode. Hydrogen production is currently a limiting factor for the production of methane in AD. The methanogenic culture on the cathode can convert hydrogen and CO2 to methane at a faster rate than in AD, producing 20-30% more methane in the biogas than AD (70-80% CH4, 30-20% CO2).
While examples of EMR technology have been reported in the literature there have been few effective pilot or commercial scale implementations (>1000 L) of this technology. The technology is relatively young and optimal conditions are not defined. Further research is needed to fully characterise the process and optimise operating conditions to reduce barriers to implementation and enable full scale, long term commercial operation. This project is sponsored by the Royal Commission for the Exhibition of 1851 and involves collaboration with WASE Ltd.