Carbamazepine biodegradation and volatile fatty acids production by selectively enriched sulfate-reducing bacteria and fermentative acidogenic bacteria

BACKGROUND The micropollutant carbamazepine (CBZ) is persistent and resistant to conventional wastewater treatment. This study investigated the role of fermentative acidogenic bacteria (FAB) and sulfate-reducing bacteria (SRB) for CBZ biodegradation and volatile fatty acid (VFA) production. RESULTS The experimental results demonstrated that CBZ biodegradation, total organic carbon and sulfate removal efficiency reached 46%, 36% and 98%, respectively, after 144 h of operation with VFA production of acetic acid (20.72 mmol L-1), propionic acid (3.67 mmol L-1) and butyric acid (4.90 mmol L-1). However, the acetate fraction decreased from 78% to 70% with a decrease in chemical oxygen demand/sulfate (COD:SO42-) ratios from 1.06 to 0.35, respectively, suggesting that acetate was partially oxidized by SRB under substrate/COD limiting conditions. The biodegradation performance of SRB + FAB was also compared with that of a mixed microbial community (MMC). CONCLUSIONS Upon increasing the initial CBZ concentration from 42.3 to 169.2 mu mol L-1, SRB + FAB exhibited much higher CBZ biodegradation (33%) than MMC (12%). Microbial community analyses confirmed the enrichment of VFA-producing species including phylum Firmicutes (2.4% to 36.8%) and class Clostridia (1.3% to 29.6%). Moreover, aromatic and nitroaromatic compound-degrading bacteria such asEscherichiaandDesulfovibriowere also enriched. This signifies the applicability of SRB + FAB to pharmaceutical pollutant biodegradation in the environment. (c) 2020 Society of Chemical Industry (SCI)