Microbial Community Profiles Related to Volatile Fatty Acids Production in Mesophilic and Thermophilic Fermentation of Waste Activated Sludge Pretreated by Enzymolysis

Mesophilic and thermophilic anaerobic fermentation performance of waste activated sludge (WAS) pretreated by enzymes catalysis associated with microbial community shifts were investigated. WAS disintegration was boosted considerably by enzymolysis with 8750 mg/L of soluble COD release within 180 min. Mesophilic anaerobic fermentation (MAF) produced nearly equal VFA accumulation with over 3200 mg COD/L compared with that of thermophilic fermentation (TAF). Bacterial community consortia showed great shifting differences in dynamics of main T-RFs between MAF and TAF. Moreover, MAF was conducive to form intermediate bacterial community evenness compared to TAF, which preserved a robust function of VFA production. The enzymes catalysis prompted bio-energy (electricity) recovery potential of WAS organics via anaerobic fermentation (MAF/TAF) with evaluating electricity conversion efficiency of 0.75-0.82 kW·h/kg VSS (3.9 times higher than control test). Finally, this study proposed some novel thinking on future WAS treatment/management towards energy recovery coupled with energy-sufficient wastewater treatment by co-locating WAS anaerobic fermentation, MFC plant with wastewater treatment plant(s).