Sulfate in anaerobic co-digester accelerates methane production from food waste and waste activated sludge.

Affiliation

Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, China. Electronic address: [Email]

Abstract

The presence of sulfate in food waste (FW) and waste activated sludge (WAS) threatens the anaerobic co-digestion for methane production. In this study, methane production from the anaerobic co-digestion of FW and WAS at sulfate concentrations of 50, 100, and 400 mg S/L was not affected, but instead deteriorated at 200 and 300 mg S/L. However, a model-based kinetic analysis reveals that sulfate can significantly promote the conversion of rapidly biodegradable substrates by up to 93%. From a point of thermodynamic view, the presence of sulfate can stimulate sulfate-reducing bacteria acting as acetogens to convert propionate to acetate, providing an alternative metabolic pathway for methanogenesis. In the anaerobic co-digestion, regulation of sulfate can be a potential strategy to improve the efficiency of methane production. However, more research is needed to optimize the sulfate concentration and substrate types in the anaerobic co-digester.

Keywords

Anaerobic co-digestion,Food waste,Sulfate,Sulfate-reducing bacteria,Waste activated sludge,

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