Biological treatment of high strength ammonia wastewater containing 2,4-dichlorophenol in a membrane bioreactor: System performance and microbial community

Abstract

Two membrane bioreactors (toxic MBR and blank MBR) were established and compared to treat high ammonia wastewater in the presence and absence of 2,4-dichlorophenol (2,4-DCP). After 130 days operation, both MBRs expressed NH4+-N removal efficiency (>95%) and 2,4-DCP removal efficiency was (96.47 ± 1.54) %. Specific oxygen uptake rate (SOUR) data showed that nitrifying bacteria receive more severe inhibition than heterotrophic bacteria. Trans-membrane pressure (TMP) data indicated that the presence of 2,4-DCP caused more serious membrane fouling. The protein/polysaccharide ratio increased to 1.1 and 6.3 in the loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) after 2,4-DCP addition. Excitation-emission matrix (EEM) showed that TB-EPS were mainly composed of aromatic and tryptophan PN-like substances, and LB-EPS of humic acid-like and fulvic acid-like substances. The microbial community analysis showed that the abundance of Proteobacteria, Firmicutes, and Nitrospirae under 2,4-DCP stress increased from 22.56%, 27.10%, and 1.27% to 38.89%, 28.25% and 3.59%, respectively.