Effect of divalent nickel on the anammox process in a UASB reactor

• Published in: Chemosphere (Oxford) Vol. 226; pp. 934 - 944
• Main Authors: Wu, Dan, Zhang, Quan, Xia, Wen-Jing, Shi, Zhi-Jian, Huang, Bao-Cheng, Fan, Nian-Si, Jin, Ren-Cun
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.07.2019
• Subjects: Anammox; Granular sludge; Inhibition; Microbial community; Nickel; Nitrogen removal; Nitrogen removal; Anammox; Nickel; Inhibition; Granular sludge; Microbial community
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2019.03.121

The anaerobic ammonium oxidation (anammox) process has the advantages of a high nitrogen removal rate, low operational cost, and small footprint and has been successfully implemented to treat high-content ammonium wastewater. However, very little is known about the toxicity of the heavy metal element Ni(II) to the anammox process. In this study, the short- and long-term effects of Ni(II) on the anammox process in an upflow anaerobic sludge blanket (UASB) reactor were revealed. The results of the short-term batch test showed that the half maximal inhibitory concentration (IC50) of Ni(II) on anammox biomass was 14.6 mg L−1. A continuous-flow experiment was performed for 150 days of operation, and the results illustrated that after domestication, the achieved nitrogen removal efficiency was up to 93±0.03% at 10 mg L−1 Ni(II). The settling velocity, specific anammox activity and EPS content decreased as the Ni(II) concentration increased. Nevertheless, the content of heme c increased as the Ni(II) increased. These results indicate that short-term exposure to Ni(II) has an adverse impact on anammox process, but the anammox system could tolerate 10 mg L−1 Ni(II) stress after acclimation during continuous-flow operation for 150 days. High-throughput sequencing results indicated that the presence of Ni(II) had an impact on the microbial community composition in the anammox reactor, especially Candidatus Kuenenia. At Ni(II) concentrations of 0-10 mg L−1, the relative abundance of Candidatus Kuenenia decreased from 36.23% to 28.46%. •The IC50 of Ni(II) on anammox biomass was 14.64 mg L−1 in short-term assay.•The effect of Ni(II) on substrate removal kinetic behavior of anammox was studied.•The long-term effects of Ni(II) in anammox UASB reactor were evaluated.