Changes in nitrogen removal and microbiota of anammox biofilm reactors under tetracycline stress at environmentally and industrially relevant concentrations

摘要

Anammox-related processes are often applied for the wastewater treatment which contains both ammonium and antibiotics. Herein, the long-term effects of tetracycline (TC), at environmentally and industrially relevant concentrations, on the performance, anammox activity and microbial community of anammox reactors were investigated for 518 days. The control reactor (without TC exposure) was stable for nitrogen removal during the long-term operation (a nitrogen removal rate of 0.56 +/- 0.05 kg-N.m(-3).d(-1)). In the TC-added reactor, the nitrogen removal efficiency increased slightly at low TC levels (1-100 mu g/L), whereas poor anammox performance occurred at high TC concentration (1000 mu g/L). Furthermore, the concentrations of extracellular polymeric substances (EPS) were much higher at 10 mu g/L than those in the control reactor (P 0.01), whereas rapidly decreased at 1000 mu g-TC/L. Furthermore, the reactor performance was highly consistent with the variations of the heme c contents. Consistently, exposure to TC changed the abundance of anammox bacteria, e.g., an increase in Candidates Jettenia abundance occurred from 220 = 0.97% (0-10 mu g/L) to 12.13 +/- 1.66% (100 mu g/L). Similarly, the genus Denitratisoma, the most predominant denitrification bacteria, also had a higher abundance at a TC concentration of 100 mu g/L (15.60 +/- 6.42%) than other TC concentrations (5.40 +/- 2.50% and 7.65 +/- 0.55% at concentrations of 10 and 1000 mu g/L, respectively). The results can explain why the exposure of anammox bacteria to a lower TC concentration (100 mu g/L) resulted in a better nitrogen removal rate. In contrast, exposure to a high TC level (1000 mu g/L) led to a decline in the abundance of anammox bacteria and denitrifiers (1.53 +/- 0.64% and 8.18 +/- 0.63%, respectively) but an increased abundance in the nitrifier population (8.07 +/- 1.21%; P 0.01). Therefore, this study can aid in the design and operation of anammox-based processes treating sewage and industrial wastewater. (C) 2019 Elsevier B.V. All rights reserved.