Performance and mechanism of in-situ biogas upgrading using anaerobic membrane bioreactor effluent

Anaerobic membrane bioreactor (AnMBR) is considered an important alternative biogas source while efficiently purifying sewage. Improving the methane (CH 4 ) content in the AnMBR biogas in a cost-effective way is closely related to its future availability. In the study, a novel system was proposed for in-situ biogas upgrading using AnMBR effluent. The system achieves the dual goals of bioenergy recovery from sewage and biogas upgrading. Biogas upgrading results showed that the CH 4 content in upgraded biogas was 90.3% at biogas flow of 0.36 L/h, effluent flow of 2.88 L/h, and normal temperature and pressure. The mechanism analysis showed that efficient upgrading with AnMBR effluent depended on sufficiency alkali products and less N 2 and O 2 . Meanwhile, conversion efficiency of chemical oxygen demand (COD) to CH 4 of AnMBR was 78.5% under hydraulic retention time (HRT) of 8 h and organic load rate of 1.2 g COD/L/d. The novel system provides a new solution for cost-effective in-situ biogas upgrading using AnMBR effluent by integration of AnMBR with scrubbing column. • A novel system for in-situ biogas upgrading by the AnMBR effluent was proposed. • The conversion efficiency of COD to CH 4 in AnMBR was 78.52%. • The CH 4 of upgraded biogas with AnMBR effluent was 90.3%. • Advantages of AnMBR effluent were sufficient alkali products and less N 2 and O 2 . • AnMBR effluent was a new solution for cost-effective in-situ biogas upgrading.