The accumulation of multi-hydrolytic enzyme through anaerobic co-digestion of waste-activated sludge (WAS) and food waste (FW) was studied by regulating temperature, pH and the mass ratio of FW to WAS (F/W). Experimental results showed that temperature had a profound effect on the activity of the enzyme and the most suitable temperatures for the accumulation of amylase and protease were 37°C and 50°C, respectively. The highest activity of amylase and protease accumulated reached 10.29 and 19.23 U/mL at an F/W ratio of 2:1. The addition of anaerobic co-digestion solution enriching protease and amylase had positive effects on the hydrolysis of WAS. In addition, the Illumina high-throughput sequencing demonstrated that the bacterial diversity decreased, but the bacterial abundance increased during the co-digestion process of WAS and FW. The predominant strains for secreting amylase were Lactobacillus and Clostridium-sensu-strito-1, and Aeromonas was the dominant strain for secreting protease.
Keywords: Anaerobic co-digestion; enzyme; food waste; hydrolysis; waste-activated sludge.