Simultaneous Production of Methane and Acetate from Carbon Dioxide with Bioelectrochemical Systems

Reduction of CO2 to organics with bioelectrical systems has become a research area of environmental microbiology.This study constructed a bioelectrochemical system(BES) capable of reducing CO2 to CH4 and CH3COOH via abiotical H2 gas production and/or direct extracellular electron transfer. CH4 and CH3COOH were produced at rates of 17.3 mL h-1L-1 and 13.9 mg h-1L-1, respectively(at potential of-1 100 mV). The current capture efficiency reached 94.0% in batch potentiostatic experiments. Microbial characterization revealed that the microbial populations consisted of Methanobacterium palustre,Methanocorpusculum parvum, and acetogen Acetobacterium sp. These results suggested that mixed culture in BESs can convert CO2 into various organic compounds by accepting electrons in different ways.