Biocathodic performance of bioelectrochemical systems operated at low temperature

This study investigated the effects of operational temperature on cathodic performances of five bioelectrochemical reactors operated in parallel at 25–7 °C, and on the biofilm microbial community at the end of tests. Compared with the anodic biofilm, the cathodic biofilm has high stability subjected to temperature shift in the aspect of cathode potentials, redox activities, and internal resistances. The maximum power density was reduced linearly with temperature at a rate of 1.1 W/m³ °C. The bacterial community at 7 °C cathodic biofilm was dominated by four phyla including Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes with percentages of 81.7%, 8.9%, 3.3% and 1.3%, and the predominant genera were affiliated with Azoarcus sp. (56.45%), Acidovorax sp. (7.32%), Rhodococcus sp. (5.02%), Halomonas sp. (2.6%). The most vigorous metabolism of cathodic biofilm at low temperature was proposed to be biosynthesis and energy generation. The cathodic biofilm has resilient microbial community to temperature challenges.