Variation in the performance and sludge characteristics of anaerobic ammonium oxidation inhibited by copper

This study investigated the short-term inhibitory effects of Cu(II) on anaerobic ammonium oxidation (anammox) performance and sludge characteristics. The short-term inhibition, kinetic characteristics, and cumulative inhibition of Cu(II) on anammox sludge and recovery from this inhibited activity by washing with buffered solution were investigated by batch testing. The results showed that the half inhibition concentration (IC50) was 32.5 mg L-1 and that inhibition by Cu(II) on anammox was non-competitive. The cumulative toxicity of Cu(II) was severe. After the biomass was washed with buffered solution for 10 h, the suppression of anammox activity by 5 mg L-1 Cu(II) could be remitted, whereas no more than 73.0% of the pre-inhibited level of activity was regained at higher Cu(II) concentrations (over 15 mg L-1). Additionally, 8 mg L-1 Cu(II) inhibited anammox performance considerably during continuous operation, with the nitrogen removal rate (NRR) decreasing from 12.4 to nearly 0 kg m(-3) d(-1). In contrast, the anammox consortia could tolerate Cu(II) stress after domestication with a low level of Cu(II) (5 mg L-1). The performance of recovery similar to the re-startup features were simulated by a modified Boltzmann model. (C) 2014 Elsevier B.V. All rights reserved.