Simultaneous removal of triclosan and nitrate by a stable denitrifying microbial consortium

Abstract

The co-existence of antibiotics and nitrate in common in the aquatic environment, so the simultaneous removal of antibiotics and nitrate is necessary, but still challenge. In this study, a stable denitrifying microbial consortium capable of degrading triclosan was isolated from a long-term operated denitrifying bioreactor used for biological nitrate removal. The microbial consortium consisted of Pseudomonas (93.47 %), Burkholderia (1.56 %) and Cupriavidus (1.17 %) based on high-throughout sequencing analysis. The denitrification efficiency was higher under anoxic condition than that under aerobic condition. However, the accumulation of nitrite was observed under anoxic condition, with maximal concentration of 10.2 mg/L. Triclosan had negative impact on denitrification under both aerobic and anoxic conditions. The pseudo first-order kinetic constant of denitrification was 0.0303 h−1 and 0.0468 h−1 under aerobic and anoxic conditions, respectively. Dechlorination of triclosan was observed under aerobic condition but not under anoxic condition. Hydroxylated-triclosan, 2,4-dichlorophenol and phenol were identified as intermediate products of triclosan degradation.