Effects of FeO nanoparticles on anaerobic digestion enzymes and microbial community of sludge.

FeO nanoparticles (NPs) have potential effects on the anaerobic digestion of excess sludge. The effects of different concentrations of FeO NPs (0, 100, 200, 400 and 600 mg/L) on enzymes and microorganisms in anaerobic digestion were studied to explore the mechanism of the effect of FeO NPs on anaerobic digestion. The results showed that 100, 200 and 400 mg/L FeO NPs could promote anaerobic digestion, and 200 mg/L FeO NPs had the most obvious promoting effect. The activities of protease, cellulase, dehydrogenase, acetic kinase and coenzyme F420 in the 200 mg/L FeO NPs group reached 120 U/mg VS, 71.75 U/g VS, 135 U/mL, 94 mol/L, 1.37 umol/g VSS, respectively, which were 3.8, 1.5, 1.2, 1.2 and 1.6 times of the blank group, respectively. However, when the concentration of FeO NPs reached 600 mg/L, the activities of cellulase, dehydrogenase and acetic kinase were lower than those of the blank group, and anaerobic digestion was inhibited. The above conclusions can also be confirmed by high-throughput sequencing. The abundance of and in the 200 mg/L FeO NPs group was 8.8% and 4.1% respectively, and abundance was 69%, which was more conducive to decomposition acetic acid into CH. To explore the effects of Fe3O4 NPS on enzyme activity and microorganisms.200mg/L FeO NPs could significantly promote the activity of enzyme.200mg/L FeO NPs could promote the diversity of bacterial and archaeal communities.600mg/L FeO NPs could inhibit some enzyme activities and microbial community diversity.