Highly efficient low-temperature biodegradation of nitrogenous pollutions in domestic wastewater via immobilized-microbial bioaugmentation coupled with hybrid membrane bioreactor

Bioaugmentation has been widely applied to domestic wastewater treatment. However, low temperature significantly inhibits the treatment efficacy of bioaugmentation. In this study, the engineered Paracoccus denitrificans expressing AMO and Nirs (rPARD) was constructed. The removal efficiencies of rPARD coupled with hybrid membrane bioreactor (HMBR) for treating domestic wastewater under low temperature (4–8 °C) were investigated. Immobilized-microbial bioaugmentation using rPARD (irPARD) coupled with HMBR (irPARD-HMBR) enhanced the nitrogenous metabolism by driving heterotrophic nitrification-aerobic denitrification. The removal efficacies of ammonia nitrogen (NH4-H), total nitrogen (TN), chemical oxygen demand (COD), and biochemical oxygen demand (BOD) in irPARD-HMBR were 95.6 %, 92.5 %, 96.2 % and 98.2 %, respectively. Microbial analysis demonstrated that the relatively high abundance of rPARD (75.4 %) and functional genes (72.5 %) upregulated the activities of key enzymes involved in nitrogenous metabolism. In addition, irPARD significantly increased the abundance of nitrogen metabolism-related functional genes in the treatment system. Furthermore, the application of irPARD-HMBR showed shorter hydraulic retention time (HRT), sludge retention time (SRT), lower operational cost (0.32 yuan/m3) and greenhouse gas (GHG) emissions (0.56 kg CO2eq/d). In conclusion, findings indicate that irPARD-HMBR presents potential application for treating domestic wastewater under low temperature.