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Nitrogen removal from wastewater through partial nitrification/ Anammox process Kosari, Fatemeh

Abstract

Nitrogen removal from wastewater through partial nitrification/Anammox was investigated. The objectives of the research were divided to three distinctive and related areas: Partial Nitrification (PN) process, Anammox reaction and green house gases emission from partial nitrification and Anammox reactor. In the PN process, research objectives were to determine: 1) the effect Dissolved Oxygen concentration, alkalinity on the PN reaction 2) evaluation of continuous moving bed biofilm reactor (MBBR) and sequencing batch reactor (SBR) for partial nitrification process. The main goals of the Anammox process study was to investigate: 1) parameters, which affect the Anammox process 2) evaluation of continuous moving bed biofilm reactor, hybrid reactor and up-flow fixed-bed reactor for the Anammox process. In the last stage, N₂O and NO emissions from both partial nitrification and Anammox reactor under various operating conditions were determined. Partial nitrification in the sequencing batch reactor was more efficient, compared to continuous moving bed biofilm reactor. Alkalinity was investigated as a limiting factor for oxidizing more ammonium to nitrite in the PN reactor. The effluent of the MBBR contained 59.7% ammonium, 31.7 % nitrite and 8.5 % nitrate and gaseous products, such as nitrous oxide and nitrogen as initial nitrogen load. Whereas, the SBR could convert more than 45% of the ammonium to nitrite; in fact, the effluent of the SBR reactor contained 45.1% ammonium, 45.1% nitrite and 1.9% nitrate, as initial nitrogen load. Subsequent Anammox treatment, after the MBBR, resulted in 38.8% additional ammonium removal and nitrite removal of 83.1 %. As a result, total ammonia removal in the combined system reached 79.1% and total nitrogen removal was 56.8 %. The Hybrid Anammox reactor removed an average of 55.8% of NH₄-N, versus 48.3% NH₄-N removal in the up-flow fixed-bed reactor. Nitrite removal in the hybrid and up-flow fixed-bed Anammox reactor was 80.8% and 62.5%, respectively. This research indicates that nitrous oxide and nitric oxide emission from partial nitrification at DO being controlled at 2 mg/L were 2.6±0.2% and 0.6±0.3% as nitrogen load, respectively. Relatively low N₂O of 0.15±0.02% was observed from the Anammox reactor, compared to partial nitrification and NO emissions was none detected.

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Attribution-NonCommercial-NoDerivatives 4.0 International