High rate anaerobic digestion of swine wastewater in an anaerobic membrane bioreactor

Efficient treatment of swine wastewater at a high rate would facilitate the development of a sustainable pig industry. In this study, to investigate methane fermentation and membrane filtration performance, an anaerobic membrane bioreactor was operated under mesophilic conditions for 207 days during four stages, with a hydraulic retention time (HRT) decreasing from 5 to 3, 2, and 1 day, and a changing of solid retention time/hydraulic retention time (SRT/HRT) ratio from 18,18 to 8 and 3.2. The results showed that a higher volumetric methane production of 1.63 L/(L.d) and a lower VFAs concentration (<200 mg/L at stable stage) could achieved when the HRT was 1 day and SRT/HRT ratio was only 3.2. The specific methanogenic activity slightly decreased under the shorter HRT, and with SRT/HRT shortening, hydro-genotrophic Methanocorpusculum tended to dominate in bulk sludge while acetoclastic Methanosaeta dominated in the biofilm. Membrane fouling was observed after 4 months with a flux decline and a significant increase in trans-membrane pressure. A serial cleaning test indicated that organic pollutants contributed highly to the membrane fouling. (C) 2019 Published by Elsevier Ltd.