Advanced nitrogen and phosphorus removal in A²O-BAF system treating low carbon-to-nitrogen ratio domestic wastewater

Abstract

A laboratory-scale anaerobic-anoxic-aerobic process (A²O) with a small aerobic zone and a bigger anoxic zone and biologic aerated filter (A²O-BAF) system was operated to treat low carbon-to-nitrogen ratio domestic wastewater. The A²O process was employed mainly for organic matter and phosphorus removal, and for denitrification. The BAF was only used for nitrification which coupled with a settling tank Compared with a conventional A²O process, the suspended activated sludge in this A²O-BAF process contained small quantities of nitrifier, but nitrification overwhelmingly conducted in BAF. So the system successfully avoided the contradiction in sludge retention time (SRT) between nitrifying bacteria and phosphorus accumulating organisms (PAOs). Denitrifying phosphorus accumulating organisms (DPAOs) played an important role in removing up to 91% of phosphorus along with nitrogen, which indicated that the suspended activated sludge process presented a good denitrifying phosphorus removal performance. The average removal efficiency of chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), and\mathrm{N}{\mathrm{H}}_{\mathrm{4}}^{+}-\mathrm{N} were 85.56%, 92.07%, 81.24% and 98.7% respectively. The effluent quality consistently satisfied the national first level A effluent discharge standard of China. The average sludge volume index (SVI) was 85.4 mL·g^-1 additionally, the volume ratio of anaerobic, anoxic and aerobic zone in A²O process was also investigated, and the results demonstrated that the optimum value was 1∶6∶2.

Keywords

Anoxic zone and biologic aerated filter (A²O-BAF) system / domestic wastewater with low carbon-to-nitrogen ratio / advanced nitrogen and phosphorus removal / denitrifying phosphorus removal

References

[1] Fan J, Tao T, Zhang J, You G L. Performance evaluation of a modified anaerobic/anoxic/oxic (A²/O) process treating low strength wastewater. Desalination, 2009, 249(2): 822-827 doi:10.1016/j.desal.2009.03.015

[2] Tchobanoglous G, Burton F L, Stensel H D. Wastewater Engineering: Treatment Disposal and Reuse. 4th ed. New York: Metcalf & Eddy Inc., McGraw-Hill Science Engineering, 2003

[3] Banu J R, Uan K, Chung I J, Kaliappan S, Yeom I T. A study on the performance of a pilot scale A2/0-MBR system in treating domestic wastewater. Journal of Environment biology, 2009, 30(6): 959-963

[4] Wang X L, Peng Y Z, Wang S Y, Fan J, Cao X. Influence of wastewater composition on nitrogen and phosphorus removal and process control in A²/O process. Bioprocess and Biosystems Engineering, 2006, 28(6): 397-404

[5] You S J, Hsu C L, Chuang S H, Ouyang C F. Nitrification efficiency and nitrifying bacteria abundance in combined AS-RBC and A²/O systems. Water Research, 2003, 37(10): 2281-2290

[6] Ding Y W, Wang L, Wang B Z, Wang Z. Removal of nitrogen and phosphorus in a combined A²/O-BAF system with a short aerobic SRT. Journal of Environment Science, 2006, 18(6): 1082-1087

[7] Chuang S H, Ouyang C F, Yuang H C, You S J. Effects of SRT and DO on nutrient removal in a combined AS-biofilm process. Water Science and Technology, 1997, 36(12): 19-27

[8] Kuba T, van Loosdrecht M C M, Brandse F A, Heijnen J J. Occurrence of denitrifying phosphorus removing bacteria in modified UCT-type wastewater treatment plants. Water Research, 1997, 31(4): 777-786

[9] Nam H U, Lee J H, Kim C W, Park T J. Enhanced biological nutrients removal using the combined fixed-film reactor with bypass flow. Water Research, 2000, 34(5): 1570-1576

[10] Mino T, van Loosdrecht M C M, Heijnen J J. Microbiology and biochemistry of the enhanced biological phosphate removal process. Water Research, 1998, 32(11): 3193-3207

[11] Barker P S, Dold P L. Denitrification behaviour in biological excess phosphorus removal activated sludge systems. Water Research, 1996, 30(4): 769-780

[12] Ahn J, Daidou T, Tsuneda S, Hirata A. Transformation of phosphorus and relevant intracellular compounds by a phosphorus-accumulating enrichment culture in the presence of both the electron acceptor and electron donor. Biotechnology and Bioengineering, 2002, 79(1): 83-93

[13] Peng Y, Wang X, Li B. Anoxic biological phosphorus uptake and the effect of excessive aeration on biological phosphorus removal in the A²/O process. Desalination, 2006, 189(1-3): 155-164

[14] Kuba T, Smolders G, van Loosdrecht M CM, Heijnen J J.Biological phosphorus removal from wastewater by anaerobic-anoxic sequencing batch reactor. Water Science and Technology, 1993, 27(5-6): 241-252

[15] Hu J Y, Ong S L, Ng W J, Lu F, Fan X J. A new method for characterizing denitrifying phosphorus removal bacteria by using three different types of electron acceptors. Water Research, 2003, 37(14): 3463-3471

[16] Hou H X, Wang S Y, Peng Y Z, Yuan Z G, Yin F, Gan W. Anoxic phosphorus removal in a pilot scale anaerobic-anoxic oxidation ditch process. Frontiers of Environmental Science & Engineering in China, 2009, 3(1): 106-111

[17] Wang Y Y, Peng Y Z, Li T W, Ozaki M. Phosphorus removal under anoxic conditions in a continuous-flow A²/N two-sludge process. Water Science and Technology, 2004, 5(6): 37-44

[18] Kapagiannidis A G, Zafiriadis I, Aivasidis A. Comparison between UCT type and DPAO biomass phosphorus removal efficiency under aerobic and anoxic conditions. Water Science and Technology, 2009, 60(10): 2695-2703

[19] Ma J, Peng Y Z, Wang S Y, Wang L, Liu Y, Ma N. Denitrifying phosphorus removal in a step-feed CAST with alternating anoxic-oxic operational strategy. Journal of Environment Science, 2009, 21(9): 1169-1174

[20] Ko K B, Park N Y, Oh Y K, Lee K S, Yu Y S. Denitrification and phosphorus release under anoxic conditions in an anoxic-anaerobic-aerobic BNR process. Environmental Technology, 2003, 24(6): 693-702 doi:10.1080/09593330309385605

Acknowledgements

This work was supported by the project of Scientific Research Base And Scientific Innovation Platform of Beijing Municipal Education Commission (No. PXM2008_014204_050843), and Supported by State Key Laboratory of Urban Water Resource and Environment (HIT) (No. QAK200802).

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2014 Higher Education Press and Springer-Verlag Berlin Heidelberg