Anaerobic co-digestion of waste activated sludge and fish waste: Methane production performance and mechanism analysis

Abstract

The performances of anaerobic co-digestion (AcD) of waste activated sludge (WAS) and fish waste (FW) were studied through mesophilic biochemical methane potential test. Mixtures of various compositions (0, 1.5, 3, 6 and 10% of FW on the volume basis) were tested as the AcD substrates. Experimental results showed that 1.5% and 3% of FW addition could enhance the cumulative methane production remarkably, increasing from 212.3 mL CH4/g VSfed (100% WAS) to 410.1 mL CH4/g VSfed and 683.8 mL CH4/g VSfed, respectively. However, methane producing was inhibited severely with more than 6% of FW addition, whose cumulative methane production dramatically decreased to approximately 51 mL CH4/g VSfed. Mechanism analysis showed that large amounts of fatty acids accumulation occurred during the AcD with FW addition above 6%, leading to methanogenesis process failure. Microbial community analysis showed that methane producing during AcD was dominated by hydrogenotrophic and methylotrophic methanogenesis pathways led by Methanobacterium and Methanomassiliicoccus.