Enhanced wastewater treatment with high o-aminophenol concentration by two-stage MABR and its biodegradation mechanism.

A two-stage bench-scale membrane-aerated biofilm reactor (MABR) was developed to treat wastewater containing high o-aminophenol (OAP) content. Long-term process showed that MABR-1 can achieve the removal rates of 17.6 g OAP/m2 d and 29.4 g COD/m2 d. MABR-2 can effectively perform more than 90% TN removal with the addition of external glucose. Pseudomonas and Nitrosomonas were the key functional genera in MABR-1 and MABR-2, respectively. Functional genes related to OAP degradation, including amnA,B,D, dmpC,H, mhpD,E,F, and bphH,I,J, were detected, and the involved enzymes were predicted. The OAP-degrading species and functional contribution analysis indicated that OAP can be metabolized by a single Pseudomonas or by the synergistic effects of bacteria, mainly including Cupriavidus, Thauera, unclassified Sphingomonadaceae, Lysobacter, and Azotobacter or by the cooperation of all the bacteria above. These diversified patterns guaranteed the high efficiency for OAP removal in MABR when treating wastewater with high OAP concentration.