Unveiling the mechanisms of how vivianite affects anaerobic digestion of waste activated sludge

Recently, phosphorus recovery as vivianite from sludge digestion system has attracted increasing attention because of its high recovery efficiency and economic value. However, the potential impact of vivianite on anaerobic digestion of waste activated sludge remains largely unknown. This study therefore aims to provide such support. Experimental results revealed that the maximal methane yield decreased from 103.55 to 76.55 mL/ g volatile solids, with the vivianite level increasing from 0 to 500 mg P/L. Mechanism explorations showed that vivianite caused more substrates remaining in tightly-bound extracellular polymeric substances, and thus sup -pressed sludge solubilization. In addition, it was observed that hydrolysis, acidiogenesis, acetogenesis and methanogenesis bio-processes were all inhibited by vivianite. Microbial analysis revealed that vivianite signif-icantly decreased the relative abundances of hydrolytic microbes, acidogens and methanogens. Further inves-tigation showed that vivianite benefited sludge agglomeration and can enhance the mass transfer resistance of anaerobic digestion, further supporting the inhibitions on anaerobic digestion.

Automated summary

This study revealed that vivianite significantly inhibits anaerobic digestion of waste activated sludge, leading to a decrease in methane yield, an increase in substrate remaining, and an impact on microbial communities.