Efficiency of microbial fuel cells based on the sulfate reduction by lactate and glucose

The influence of lactate and glucose, used as electron donors on the rate of sulfate reduction, electricity generation and microbial communities in anodic chamber of microbial fuel cells, was studied. Effective sulfate and chemical oxygen demand removal was achieved at different hydraulic retention times by the laboratory installations, consisting of anaerobic fixed-bed reactor and microbial fuel cell with air–cathode. The highest maximum power density of 349 mW/m2 was obtained in the lactate-fed microbial fuel cell under hydraulic retention time of 66 h. The type of electron donor had a great impact on the composition of the microbial community. The metagenomic data obtained showed that the most abundant phylum in both bacterial communities was Proteobacteria—67% and 46% when using lactate and glucose as an electron donor, respectively. Euryarchaeota was found in significant quantities (11.57%) in the microbial communities cultivated on lactate, whereas when using glucose, they were 0.01%. The bacterial community at glucose was characterized with the phyla belonging to Verrucomicrobia (15.11%) and Spirochaetes (17.26%). In both microbial communities in anodic chamber were presented sulfate-reducing bacteria that can incompletely oxidize the organic compound usually with acetate as an end product, as the dominant microbial species among sulfate-reducing bacteria was Desulfomicrobium baculatum (3.21%) in the microbial fuel cell at lactate, and Desulfovibrio mexicanus dominated (2.73%) in the microbial fuel cell at glucose.