Short-term inhibitory effects of TiO2 NPs on Anammox process

Abstract

Anammox process has brought about cost-effective, eco-friendly, and innovative technologies to wastewater treatment by reducing the operational cost of treatment plants and decreasing greenhouse gas emissions. Titanium dioxide (TiO2), as one of the most prevalent nanoparticles (NPs) in the world, is being used in various consumer products and applications. In recent years, studies have focused on potential toxicological impacts of NPs on biological processes due to their endless production and consumption. In this context, the first time in the literature, 24 h acute TiO2 NPs exposure on Anammox process was investigated. Deterioration on anammox activity gradually increased with increasing applied TiO2 NPs concentration. At 300 mg/L exposure dose, nitrogen removal rate dramatically decreased to 37.09 ± 0.24 mgN/ gVSS.d and a severe inhibition (80.57% ± 1.17%) was observed. Among the several curve fit models, non-linear second order polynomial (quadratic) model was the best fit one with IC50 of 154 mg/L. Scanning electron microscope (SEM) images demonstrated the tendency of TiO2 NPs to aggregate and attach to the surface of the bacteria. Extracellular polymeric substance (EPS) response of anammox bacteria was also investigated and it was found that, the total EPS content gradually decreased by increasing TiO2 NPs concentration.

Keywords

• Anammox bacteria
• Nanoparticles
• Acute inhibition
• Nanoparticle toxicity

References

1. Bhushan, B. (2017). Introduction to Nanotechnology In B. Bhushan (Ed.), Springer Handbook of Nanotechnology (4 ed., pp. 1-18). Berlin, Germany: Springer.
2. Cao, Y. S., van Loosdrecht, M. C. M., & Daigger, G. T. (2017). Mainstream partial nitritation-anammox in municipal wastewater treatment: status, bottlenecks, and further studies. Applied Microbiology and Biotechnology, 101(4), 1365-1383.
3. Cervantes-Aviles, P., Pinas, N. C., Ida, J., & Cuevas-Rodriguez, G. (2017). Influence of wastewater type on the impact generated by TiO2 nanoparticles on the oxygen uptake rate in activated sludge process. Journal of Environmental Management, 190, 35-44.
4. Chen, R., & Chen, C. (2017). Environment, Health and Safety Issues in Nanotechnology. In B. Bhushan (Ed.), Springer Handbook of Nanotechnology (pp. 1559-1586). Berlin, Germany: Springer.
5. Gupta, R., & Xie, H. (2018). Nanoparticles in Daily Life: Applications, Toxicity and Regulations. Journal of Environmental Pathology Toxicology and Oncology, 37(3), 209-230.
6. He, Q. L., Gao, S. X., Zhang, S. L., Zhang, W., & Wang, H. Y. (2017). Chronic responses of aerobic granules to zinc oxide nanoparticles in a sequencing batch reactor performing simultaneous nitrification, denitrification and phosphorus removal. Bioresource Technology, 238, 95-101.
7. Heil, J., Vereecken, H., & Bruggemann, N. (2016). A review of chemical reactions of nitrification intermediates and their role in nitrogen cycling and nitrogen trace gas formation in soil. European Journal of Soil Science, 67(1), 23-39.
8. Hou, J., Miao, L. Z., Wang, C., Wang, P. F., Ao, Y. H., & Lv, B. W. (2015). Effect of CuO nanoparticles on the production and composition of extracellular polymeric substances and physicochemical stability of activated sludge flocs. Bioresource Technology, 176, 65-70.

9. Huangfu, X. L., Xu, Y. H., Liu, C. H., He, Q., Ma, J., Ma, C. X., & Huang, R. X. (2019). A review on the interactions between engineered nanoparticles with extracellular and intracellular polymeric substances from wastewater treatment aggregates. Chemosphere, 219, 766-783.
10. Jin, R. C., Yang, G. F., Yu, J. J., & Zheng, P. (2012). The inhibition of the Anammox process: A review. Chemical Engineering Journal, 197, 67-79.