Pollutant removal, electricity generation and microbial community in an electrochemical membrane bioreactor during co-treatment of sewage and landfill leachate

A three-chamber electrochemical membrane bioreactor (EMBR) with a microbial fuel cell (MFC) was employed to co-treat synthetic wastewater and 20% landfill leachate (LFL) and produce electrical energy. We observed the following removal rates: 98 +/- 1% of BOD5,20, 86 +/- 5% of COD, 79 +/- 2% of N-NH4+, 72 +/- 6% of DOC and 43 +/- 3% of N-total, while voltage generation was 463 +/- 41 mV. The EMBR compartments showed distinct microbial communities and inferred metabolic pathways. Acinetobacter spp. was the most abundant bacteria in the anodic biofilm and has an important role in energy generation, as noted elsewhere. Meanwhile, the high abundance of Nitrospira spp. in the cathodic biofilm indicated its importance in the nitrification process in this system, essential for treating matrices with high-nitrogen content, such as LFL. Important abundant metabolic pathways inferred in the EMBR also included aerobic chemoheterotrophs, fermenters, degraders of aromatic compounds/hydrocarbon, and denitrifiers. Clearly, metabolic groups showed that microbial communities developed in the EMBR can degrade organic matter and remove toxic compounds (e.g., aromatic compounds) and nitrogen from LFL while producing energy. Furthermore, this study indicated that a MBR coupled with MFC create a great system for the co-treatment of LFL with wastewater, achieving both pollutant removal and electrical energy generation.