Performance evaluation and microbial community analysis of a continuous stirred tank reactor-anaerobic - anaerobic ceramic membrane bioreactor system for practical swine wastewater treatment

To treat swine wastewater from a practical piggery, a continuous stirred tank reactor (CSTR)-anaerobic ceramic membrane bioreactor (AnCMBR) was operated for 201 days. A high chemical oxygen demand (COD) removal efficiency of 95 % and biogas production rate of 0.31 L/L center dot d were achieved at an organic loading rate (OLR) of 1.19 g-COD/L center dot d. Although the free ammonia concentration reached a maximum of 200 mg/L during the last operational phase, no evident inhibitory effect on AnCMBR performance was observed. Microbial community analyses indicated that six bacterial phyla were responsible for the hydrolysis, acidification, and fermentation of organics and environmental stabilization. Hydrotrophic methanogenic archaea were dominant, indicating that the main methane production pathway involved the use of H2 2 and CO2 2 as substrates. The results demonstrated that CSTR-AnCMBR systems exhibit excellent organics removal performance and energy recovery at high organic concentrations and possess strong anti-shock ability. Thus, they represent alternative green and sustainable anaerobic technologies for practical swine wastewater treatment.