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

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 (Fe2+) 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 SO42-/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 SO42-/COD ratio was increased from 0.1 to 2, the ratio of COD converting to CH4 was decreased from 80.85% to 20.16%, while the ratio of COD used for SO42- 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%.