Specific microbial diversity and functional gene (AOB amoA) analysis of a sponge-based aerobic nitrifying moving bed biofilm reactor exposed to typical pharmaceuticals

Abstract

Four bench-scale sponge-based aerobic nitrifying moving bed biofilm reactors (MBBRs) were used to treat municipal wastewater containing typical pharmaceuticals (1 mg/L, 2 mg/L and 5 mg/L). This preliminary research aims to investigate the effects of sulfadiazine (SDZ), ibuprofen (IBU) and carbamazepine (CBZ) on nitrification performance and explore specific microbial diversity and functional gene (Ammonia-oxidizing bacteria (AOB), amoA) of MBBRs. After 90 days of operation, the MBBR without pharmaceuticals could remove up to 97.4 ± 1.5% of NH4+-N while the removals of NH4+-N by the MBBRs with SDZ, IBU and CBZ were all suppressed to varying degrees. Based on the Shannon and Chao 1 index, the specific microbial diversity and richness in biofilm samples increased at a range of 1 mg/L to 2 mg/L pharmaceuticals (SDZ, IBU or CBZ) and started decreasing after the pharmaceutical concentration was higher than 2 mg/L. The determination of functional gene (AOB amoA) showed that Proteobacteria was the most dominant bacteria within all biofilms with the relative abundance ranging from 24.81% to 55.32%. Furthermore, Nitrosomonas was the most numerous genus in AOB, followed by Campylobacter and Thauera, whose relative abundance shifted under the pressure of different pharmaceuticals.