Effects of Hydraulic Retention Time on Process Stability of Integrated Fixed Film Activated Sludge (IFAS) Biological Wastewater Treatment Process
Abstract
The objective of this study was to evaluate the effects of hydraulic retention time (HRT) on the stability of Integrated Fixed Film Activated Sludge (IFAS) wastewater treatment process. The experiments were conducted by two pilot-scale Modified Ludzack-Ettinger (MLE) systems, i.e., the system installed with Bioweb media in the aerobic zone at the filling volume of 34.5% v/v, so-called as IFAS system, and the system operated without media installed, so-called AS system. Both systems were operated at different HRTs of 8, 6 and 4 hours, at the solid retention time (SRT) of 8 days, and at the temperature of 28 ± 2 oC. The results revealed that the organic removal efficiencies were 90.4 ± 0.6%, 88.7 ± 3.2%, and 84.2 ± 10.2%, respectively, in AS system and were 87.6 ± 3.0%, 85.4 ± 3.7% and 87.7 ± 4.8%, respectively, in IFAS system. Nitrification were 99.2 ± 0.5%, 99.4 ± 1.1%, and 97.9 ± 0.5%, respectively, for AS system and were 85.1 ± 5.61%, 84.3 ± 6.6%, 67.5 ± 5.6%, respectively, for IFAS system, at the HRTs of 8, 6, and 4 hours, respectively. The reductions of HRTs had the negative effects on the organic removal efficiencies in the AS system because sludges were washed out from the final clarifier due to insufficient settling time and excessive filamentous bacteria resulting in bulking sludge. The negative effects of HRT were resulted in the IFAS system for nitrification because the diffusion time of substrates into the biofilm layers were limited at higher flowrates. It appears that the capacities of AS system for organics and nitrogen removals were higher than IFAS system at the SRT of 8 days and at the HRTs of 8, 6 and 4 hours, respectively, due to the limitations of substrates diffusion. The results indicate that the HRT has a negatively impact on the stability of IFAS system at the SRT of 8 days and the conventional AS should be used instead for the wastewater treatment. Keywords : hydraulic retention Time ; IFAS, stability ; biofilm ; nitrificationReferences
Arias, A., Alvarino, T., Allegue, T., Suárez, S., Garrido, J.M. & Omil, F. (2018). An innovative wastewater treatment technology based on UASB and IFAS for cost-efficient macro and micropollutant removal. Journal of Hazardous Materials, 359, 113-120.
Grady, C.P.L., Daigger, G.T., & Lim, H.C. (1999). Biological Wastewater Treatment. New York :
Marcel Dekker, Inc.
Hubbell, S.B., Pehrson, R., & Schuler, A. (2006). Eight years of successful cold weather with Integrated Fixed Film/Activated Sludge. In Proceedings of the Water Environment Federation 2006. (pp. 240-250). Virginia: Water Environment Federation.
Jabari, P., Munz, G. & Oleszkiewicz, J.A. (2014). Selection of denitrifying phosphorous accumulating organisms in IFAS systems: comparison of nitrite with nitrate as an electron acceptor. Chemosphere, 109, 20-27.
Li, L. & Visvanathan, C. (2019). Effect of PVA-gel filling ratio in attached growth membrane bioreactor for treating polluted surface water. Environmental Technology, 40(2), 219-225.
Mannina, G., Capodici, M., Cosenza, A., Trapani, D.D. & Ekama, G.A. (2018). The effect of the solids and hydraulic retention time on moving bed membrane bioreactor performance. Journal of Cleaner Production, 170, 1305-1315.
Mannina, G. & Viviani, G. (2017). Hybrid moving bed biofilm reactors: an effective solution for upgrading
a large wastewater treatment plant. Water Science & Technology, 60(5), 1103-1116.
Moretti, P., Choubert, J.M., Canler, J.P., Petrimaux, O., Buffiere, P., & Lessard, P. (2015). Understanding the contribution of biofilm in an integrated fixed-film-activated sludge system (IFAS) designed for nitrogen removal. Water Science & Technology, 71(10), 1500-1506.
Ødegaard, H. (2017). New applications for MBBR and IFAS systems. In G. Mannina (Eds.), Frontiers in Wastewater Treatment and Modelling (FICWTM 2017) (pp. 499-507). Springer International Publishing.
Sriwiriyarat, T., Ungkurarate, K., Fongsatikul, P., & Chinwetkitvanich, S. (2008a). Effects of dissolved oxygen on biological nitrogen Removal in Integrated Fixed Film Activated Sludge (IFAS) wastewater treatment processes. Journal of Environmental Science and Health, Part A-Toxic/Hazardous Substances & Environmental Engineering, 43(5), 518-527.
Sriwiriyarat, T., Pittayakool, K., Fongsatitkul, P., & Chinwetkitvanich, S. (2008b). Stability and capacity enhancements of activated sludge process by IFAS technology. Journal of Environmental Science and Health, Part A-Toxic/Hazardous Substances & Environmental Engineering, 43(11), 1318-1324.
Tchobanoglous, G., Burton, F.L., & Stensel, H.D. (2003). Wastewater Engineering: Treatment and Reuse. New York: Metcalf & Eddy, Inc.
Grady, C.P.L., Daigger, G.T., & Lim, H.C. (1999). Biological Wastewater Treatment. New York :
Marcel Dekker, Inc.
Hubbell, S.B., Pehrson, R., & Schuler, A. (2006). Eight years of successful cold weather with Integrated Fixed Film/Activated Sludge. In Proceedings of the Water Environment Federation 2006. (pp. 240-250). Virginia: Water Environment Federation.
Jabari, P., Munz, G. & Oleszkiewicz, J.A. (2014). Selection of denitrifying phosphorous accumulating organisms in IFAS systems: comparison of nitrite with nitrate as an electron acceptor. Chemosphere, 109, 20-27.
Li, L. & Visvanathan, C. (2019). Effect of PVA-gel filling ratio in attached growth membrane bioreactor for treating polluted surface water. Environmental Technology, 40(2), 219-225.
Mannina, G., Capodici, M., Cosenza, A., Trapani, D.D. & Ekama, G.A. (2018). The effect of the solids and hydraulic retention time on moving bed membrane bioreactor performance. Journal of Cleaner Production, 170, 1305-1315.
Mannina, G. & Viviani, G. (2017). Hybrid moving bed biofilm reactors: an effective solution for upgrading
a large wastewater treatment plant. Water Science & Technology, 60(5), 1103-1116.
Moretti, P., Choubert, J.M., Canler, J.P., Petrimaux, O., Buffiere, P., & Lessard, P. (2015). Understanding the contribution of biofilm in an integrated fixed-film-activated sludge system (IFAS) designed for nitrogen removal. Water Science & Technology, 71(10), 1500-1506.
Ødegaard, H. (2017). New applications for MBBR and IFAS systems. In G. Mannina (Eds.), Frontiers in Wastewater Treatment and Modelling (FICWTM 2017) (pp. 499-507). Springer International Publishing.
Sriwiriyarat, T., Ungkurarate, K., Fongsatikul, P., & Chinwetkitvanich, S. (2008a). Effects of dissolved oxygen on biological nitrogen Removal in Integrated Fixed Film Activated Sludge (IFAS) wastewater treatment processes. Journal of Environmental Science and Health, Part A-Toxic/Hazardous Substances & Environmental Engineering, 43(5), 518-527.
Sriwiriyarat, T., Pittayakool, K., Fongsatitkul, P., & Chinwetkitvanich, S. (2008b). Stability and capacity enhancements of activated sludge process by IFAS technology. Journal of Environmental Science and Health, Part A-Toxic/Hazardous Substances & Environmental Engineering, 43(11), 1318-1324.
Tchobanoglous, G., Burton, F.L., & Stensel, H.D. (2003). Wastewater Engineering: Treatment and Reuse. New York: Metcalf & Eddy, Inc.
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Published
2021-01-06
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