The influence of biochar supported nano‐zero valent iron on the anaerobic digestion of sulfate wastewater

Abstract In this study, the effect of biochar supported nano‐zero valent iron (nZVI/BC) on anaerobic digestion of sulfate wastewater including methane yield, total volatile fatty acids, COD balance, sulfur balance, variation of iron (Fe 2+ ) and microbial community structure was investigated by a batch‐scale experiment. The results showed that nZVI/BC could effectively maintain the stability of anaerobic digestion even at a high sulfate concentration. At SO 4 2− /COD = 0.1 with 2 g nZVI/BC, the maximum methane yield ( B max ) and maximum methane production rate ( R max ) were obtained with a value of 3940.6648 mL and 553.6266 mL/day, respectively. When the SO 4 2− /COD ratio was increased from 0.1 to 2, the ratio of COD converting to CH 4 was decreased from 80.85% to 20.16%, while the ratio of COD used for SO 4 2− reduction was increased from 8.79% to 77.96%. Meanwhile, nZVI/BC could enrich the hydrogentrophic Methanobacterium especially Methanobacterium with an average relative abundance of 75.86%.