The effect of current on chemicals production in annular double-chamber microbial electrosynthesis reactor with ethanol as electron donor.

The efficient production of C4 compounds (e.g., butyrate) from CO2 in microbial electrosynthesis (MES) systems faces persistent challenges. This study employed an annular double-chamber MES reactor with ethanol as electron donor to systematically investigate chemicals generation under three controlled currents (50 mA, 100 mA, and 150 mA). The results showed MES with 50 mA can produce the highest butyrate concentrations of 8.7 g/L with average yield of 0.62 g/L/d, and its electron recovery efficiency reached a maximum of 94.4%. In contrast, acetate became the primary product in MES at 100 mA and 150 mA. The elevated abundance of Clostridium_sensu_stricto_12 correlates with enhanced butyrate synthesis under 50 mA. Low current (50 mA) combined with minimized electrode spacing in a DC-powered annular double-chamber reactor significantly enhances C4 production efficiency. This study provides a new strategy for generating long carbon chain chemicals in MES.