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Enhancing the stability and efficiency of the anammox process in plug-flow integrated fixed-film activated sludge (IFAS) reactors through alternating anoxic/aerobic (A3) conditions

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Abstract

The breakthrough of this study was the development of plug-flow integrated fixed-film activated sludge (IFAS) reactors operated with alternating anoxic/aerobic (A3) conditions for enhanced anammox processes. The energy-saving capacity and efficiency of this A3-IFAS system was compared with an identical IFAS reactor operated with continuous low oxygen aeration (CLOA) through a test period of 141 days. At the nitritation start-up phase, the nitrite in the effluent of the A3-IFAS system quickly accumulated to 77.9%, which was higher than that of the CLOA-IFAS system (61.7%). The A3-IFAS system reached 94.1 ± 4.0% of total inorganic nitrogen (TIN) removal in the stabilization stage, which was higher than that in the CLOA-IFAS system (66.7 ± 5.3%). A3-IFAS maintained stable partial nitrification and TIN removal, whereas the nitritation in CLOA-IFAS was disturbed on the 96th day and the TIN removal became unstable. Quantitative real-time polymerase chain reaction (qPCR) analysis indicated that ammonia-oxidizing bacteria (AOB) were dominant in both IFAS reactors, while the amount of nitrite-oxidizing bacteria (NOB) in the CLOA-IFAS system was 5.27 times that in the A3-IFAS system. The kinetic analysis revealed that the ratio of the AOB specific growth rate (μAOB) and NOB specific growth rate (μNOB) in A3-IFAS was 4.09, which was higher than that (3.1) in the CLOA-IFAS system, implying that the low growth rate of NOB in anoxic zones is the main reason for the stable nitritation and high TN removal in A3-IFAS.

Graphical abstract: Enhancing the stability and efficiency of the anammox process in plug-flow integrated fixed-film activated sludge (IFAS) reactors through alternating anoxic/aerobic (A3) conditions

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Publication details

The article was received on 02 Jan 2019, accepted on 23 Mar 2019 and first published on 06 Apr 2019


Article type: Paper
DOI: 10.1039/C9EW00004F
Citation: Environ. Sci.: Water Res. Technol., 2019, Advance Article

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    Enhancing the stability and efficiency of the anammox process in plug-flow integrated fixed-film activated sludge (IFAS) reactors through alternating anoxic/aerobic (A3) conditions

    C. Liu, W. Liu, L. Wu and Y. Peng, Environ. Sci.: Water Res. Technol., 2019, Advance Article , DOI: 10.1039/C9EW00004F

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