Short-Term Effects of CuO, ZnO, and TiO_2 Nanoparticles on Anammox

摘要

Anaerobic ammonium oxidation (Anammox) is attracting significant attention for use in mainstream sewage treatment. However, its application is limited by sensitivity of anaerobic ammonia-oxidizing bacteria (AAOB) to environmental conditions. Use of nanoparticles (NPs) for sewage treatment has increased in recent years, but so has the risk of NPs entering into municipal sewage. In this study, three identical sequencing batch reactors were fed with CuO, ZnO, and TiO2 NPs in different concentrations (0, 1, 5, 10, 20, and 50 mg/L) to study the short-term effects of the NPs on Anammox. Results showed that ZnO and CuO NPs had a similar effect on Anammox, that is, both NPs at low concentrations (1 mg/L) significantly suppressed nitrogen removal. Reactors also exhibited self-adaptation to ZnO NPs at concentrations in the range 5-20 mg/L and CuO NPs in the range 10-50 mg/L. ZnO and CuO NPs exerted different levels of inhibition on Anammox within the experimental range of concentrations (1-50 mg/L). TiO2 NPs were beneficial for Anammox and improved nitrogen removal at low concentrations, but significantly suppressed AAOB bioactivity at high concentrations (1 mg/L). However, they had no impact on Anammox at a concentration of 50 mg/L due to NP aggregation.