Impact of nZVI and nZVI/BC on the anaerobic digestion of piggery wastewater

In this study, nanoscale zero valent iron (nZVI) and biochar supported zero valent iron (nZVI/BC) mediated anaerobic digestion of piggery wastewater were investigated. The variation of COD removal rate, methane yield, kinetics modeling and microbial community analysis was analyzed. COD removal rate was increased by 7.46–14.79% respectively for 1, 2, 3 and 4 g nZVI. While COD removal rate was increased by 7.90–12.83% respectively for 1, 2, 3 and 4 g nZVI/BC. Compared with the control group, the accumulated methane yield was increased by 24.17–30.22% and 29.2–46.7% respectively for nZVI and nZVI/BC. Meanwhile, the accumulated hydrogen sulfide concentration was greatly reduced which was decreased from 8.32 ml (control group) to 0.40 ml (nZVI) and 0.22 ml (nZVI/BC). The variation of microbial community showed that nZVI could increase the relative abundance of Methanobacterium, longlinea and syntrophobacter, while nZVI/BC provides a more suitable environment for the growth of Mesotoga, Pertrimonas and Longilinea.