Effects on mesophilic anaerobic digestion performance of corn stalk with the addition/pretreatment of depolymerization wastewater

To develop the economic anaerobic digestion (AD) pretreatment technology, the digestive performance of corn stalk (CS) with the addition/pretreatment of depolymerization wastewater (DW) was evaluated. In this study, CS was pretreated by DW for 0 day (Only added) or 3 days, namely T0 and T1, respectively, and a mesophilic AD was performed with the whole slurry (CS and DW). Results showed that the addition of DW introduced digestive substrates, i.e. acetic acid, into the system, which promoted the hydrolysis of CS. The addition/pretreatment of DW changed the reducing sugar content (RS), pH and volatile fatty acids (VFAs) content, and then increased cumulative methane production. The maximum cumulative methane production was achieved in T1 (160.77 mL/g VS), followed by T0 (152.87 mL/g VS) and control group (CK, 138.29 mL/g VS). Microbial community analysis indicated this phenomenon was caused by the increasing activity of the hydrolytic bacteria. The addition of DW slightly facilitated the hydrolytic and acidogenic stage, and the pretreatment further facilitated this stage. This study proposed a new pretreatment for AD, which paved a way for the utilization of DW.