Simultaneous electricity generation and microbially-assisted electrosynthesis in ceramic MFCs

•MFCs synthesise alkali as a direct product of electricity generation — not consumption.•Electric current and up to 68 mL of alkaline solution was produced from the breakdown of wastewater.•The maximum power performance of a single MFC obtained by polarisation curve was 2.58 mW.•Cost effective ceramic MFCs with internal cathode achieved 92% COD reduction.•Energy generated from ceramic MFCs operated LED light for 7 days.

To date, the development of microbially assisted synthesis in Bioelectrochemical Systems (BESs) has focused on mechanisms that consume energy in order to drive the electrosynthesis process. This work reports – for the first time – on novel ceramic MFC systems that generate electricity whilst simultaneously driving the electrosynthesis of useful chemical products. A novel, inexpensive and low maintenance MFC demonstrated electrical power production and implementation into a practical application. Terracotta based tubular MFCs were able to produce sufficient power to operate an LED continuously over a 7 day period with a concomitant 92% COD reduction. Whilst the MFCs were generating energy, an alkaline solution was produced on the cathode that was directly related to the amount of power generated. The alkaline catholyte was able to fix CO2 into carbonate/bicarbonate salts. This approach implies carbon capture and storage (CCS), effectively capturing CO2 through wet caustic ‘scrubbing’ on the cathode, which ultimately locks carbon dioxide.