Enhancing methanogenesis from anaerobic digestion of propionate with addition of Fe oxides supported on conductive carbon cloth.

In this study, a FeO supported on conductive carbon cloth (FC) was prepared and supplemented into anaerobic digestion reactors to improve propionate degradation. In the FC-supplemented reactors, the cumulative methane production and propionate degradation increased by 15.4% and 19.67% compared with those of the control, respectively. Less methane production with H/CO as the sole substrate in the culture taken from the FC reactors suggested that interspecies hydrogen transfer in the FC reactors was weaker. These results suggested that direct interspecies electron transfer (DIET) was established in the FC reactors to improve the performance. FeO increased the secretion of electron shuttle components of extracellular polymeric substances to increase electron exchange capacity of biomass of the FC reactors, which further facilitated the DIET. Analysis on microbial communities confirmed that the abundance of microorganisms-related DIET in the FC reactors was higher than that in the control.