초록
This study describes the performance of bioelectrochemical systems, based on electrochemically active mixed culture, capable of reducing CO<SUB>2</SUB> to CH<SUB>4</SUB> and CH<SUB>3</SUB>COOH via direct and/or indirect extracellular electron transfer. The metabolic pathway and end products of this mixed culture were highly dependent on the set cathode potentials. Only CH<SUB>4</SUB> and H<SUB>2</SUB> were produced when the cathode potentials were set in the range from -850 to -950 mV (vs. Ag/AgCl). At potentials more negative than -950 mV, CH<SUB>4</SUB>, H<SUB>2</SUB> and CH<SUB>3</SUB>COOH were simultaneously produced. With a relatively large cathode surface area of 49 cm<SUP>-2</SUP>, CH<SUB>4</SUB> and CH<SUB>3</SUB>COOH were produced at high rates of 129.32 mL d<SUP>-1</SUP> and 94.73 mg d<SUP>-1</SUP>, respectively (at potential of -1150 mV). The highest current capture efficiency reached to 97% in batch potentiostatic experiments. These results presented here suggest that mixed culture show the ability to directly accept electrons from the electrode and abiotically produce H<SUB>2</SUB> to convert CO<SUB>2</SUB> into various organic compounds.