Comparison of the enhancement of microbial electrolysis cell on mesophilic and thermophilic anaerobic digestion of swine manure

Semi-continuous experiments were conducted to compare the enhancement of microbial electrolysis cell (MEC) on mesophilic (MAD) and thermophilic (TAD) anaerobic digestion of swine manure (SM). The experimental results showed that there were significant differences between the enhancements of MEC on the two anaerobic digestions (AD), with a more pronounced effect on MAD than on TAD. MEC enhanced the methane production of MAD by 64.54 ± 11.60 % and TAD only by 17.11 ± 10.89 %, with additional low energy input of 0.17 kJ/g VS for MAD and 0.11 kJ/g VS for TAD. MEC improved the biogas production stability of both ADs for SM. Regarding organic matter removal, the enhancement rates of MEC on MAD were 18.49 ± 4.69 % and 17.21 ± 5.15 %, while those on TAD were 7.42 ± 4.90 % and 5.88 ± 2.66 %. MEC had a greater effect on the performance of MAD and a stronger effect on the microbial communities in TAD. MEC mainly enhanced the hydrolysis and methanogenesis among the four AD steps, with higher enhancement in MAD. MEC enriched acetoclastic methanogens in MAD while hydrogenotrophic ones in TAD.