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Effects of CeO2 nanoparticles on biological nitrogen removal in a sequencing batch biofilm reactor and mechanism of toxicity
- Hou, Jun, You, Guoxiang, Xu, Yi, Wang, Chao, Wang, Peifang, Miao, Lingzhan, Ao, Yanhui, Li, Yi, Lv, Bowen
- Bioresource technology 2015 v.191 pp. 73-78
- ammonia monooxygenase, bacteria, biofilm, ceric oxide, confocal laser scanning microscopy, image analysis, lactate dehydrogenase, nanoparticles, nitrate reductase, nitrites, nitrogen, nitrogen content, reactive oxygen species, scanning electron microscopes, toxicity, viability
- The effects of CeO2 nanoparticles (CeO2 NPs) exposure on biological nitrogen removal in a sequencing batch biofilm reactor (SBBR) were investigated. At low concentration (1mg/L), no significant effect was observed on total nitrogen (TN) removal. However, at high concentrations (10 and 50mg/L), the TN removal efficiency reduced from 74.09% to 64.26% and 55.17%, respectively. Scanning electron microscope imaging showed large amounts of CeO2 NPs adsorbed on the biofilm, which increased the production of reactive oxygen species. The exposure at only 50mg/L CeO2 NPs measurably affected the lactate dehydrogenase release. Confocal laser scanning microscopy showed that high concentrations of CeO2 NPs reduced bacterial viability. Moreover, after a short-term exposure, extracellular polymeric substances (EPS) were observed to increase, forming a compact matrix to protect the bacteria. The activities of nitrate reductase and ammonia monooxygenase were inhibited, but there was no significant impact on the activity of nitrite oxidoreductase.