Efficiency of microbial fuel cells based on the sulphate-reduction by ethanol

Abstract

The influence of hydraulic retention time (HRT) on the rate of sulphate-reduction and electricity generation of microbial fuel cell fed with ethanol was studied. The experiments were performed in the laboratory installation, consisting of an anaerobic fixed-bed reactor and a microbial fuel cell with air-cathode. An effective sulphate removal was achieved at hydraulic retention times 44 and 66 h. The effectiveness of COD removal raises with increasing the hydraulic retention time. The highest maximum power density of 258 mW/m2 was obtained at 22 h HRT. The use of ethanol as an electron donor had a great impact on the composition of the microbial community. The metagenomic data obtained showed that the most abundant phylum in bacterial community was Proteobacteria – 87.8 %, and particularly Gammaproteobacteria – 53,1%. The sulphate reducing bacteria that can incompletely oxidise organic compounds usually with acetate as an end product were presented in the microbial community in anodic chamber. The dominant microbial species among sulphate reducing bacteria was Desulfomicrobium mexicanus (19,79%).