Modeling and Simulation of Oxygen-Limited Partial Nitritation in a Membrane-Assisted Bioreactor (MBR)

Laboratory for Applied Physical Chemistry, Faculty of Agricultural and Applied Biological Sciences, Ghent University, Coupure Links 653, B-9000 Gent, Belgium.
Biotechnology and Bioengineering (Impact Factor: 4.13). 06/2004; 86(5):531-42. DOI: 10.1002/bit.20008
Source: PubMed


Combination of a partial nitritation process and an anaerobic ammonium oxidation process for the treatment of sludge reject water has some general cost-efficient advantages compared to nitrification-denitrification. The integrated process features two-stage autotrophic conversion of ammonium via nitrite to dinitrogen gas with lower demand for oxygen and no external carbon requirement. A nitrifying membrane-assisted bioreactor (MBR) for the treatment of sludge reject water was operated under continuous aeration at low dissolved oxygen (DO) concentrations with the purpose of generating nitrite accumulation. Microfiltration was applied to allow a high sludge retention time (SRT), resulting in a stable partial nitritation process. During start-up of the MBR, oxygen-limited conditions were induced by increasing the ammonium loading rate and decreasing the oxygen transfer. At a loading rate of 0.9 kg N m(-3) d(-1) and an oxygen concentration below 0.1 mg DO L(-1), conversion to nitrite was close to 50% of the incoming ammonium, thereby yielding an optimal effluent within the stoichiometric requirements for subsequent anaerobic ammonium oxidation. A mathematical model for ammonium oxidation to nitrite and nitrite oxidation to nitrate was developed to describe the oxygen-limited partial nitritation process within the MBR. The model was calibrated with in situ determinations of kinetic parameters for microbial growth, reflecting the intrinsic characteristics of the ammonium oxidizing growth system at limited oxygen availability and high sludge age. The oxygen transfer coefficient (K(L)a) and the ammonium-loading rate were shown to be the appropriate operational variables to describe the experimental data accurately. The validated model was used for further steady state simulation under different operational conditions of hydraulic retention time (HRT), K(L)a, temperature and SRT, with the intention to support optimized process design. Simulation results indicated that stable nitrite production from sludge reject water was feasible with this process even at a relatively low temperature of 20 degrees C with HRT down to 0.25 days.

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    • "[35] There are many different (kinetic) models, such as Monod, Contois, first-and second-order Grau (modified), Stover–Kincannon, Chen and Hashimoto and Michaelis–Menten, some of which were applied to the wastewater treatment.[36] [37] [38] [39] [40] [41] [42] [43] [44] [45] Only few modelling studies are available concerning Anammox reactors. For example, in an Anammox non-woven membrane reactor and in an Anammox up-flow filter, the second-order Grau and the modified Stover–Kincannon seem to be the best for describing nitrogen removal.[46–48] "
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    ABSTRACT: Anammox has shown its promise and low cost for removing nitrogen from high strength wastewater such as landfill leachate. A reactor was inoculated with nitrification-denitrification sludge originating from a landfill leachate treating waste water treatment plant. During the operation, the sludge gradually converted into red Anammox granular sludge with high and stable Anammox activity. At a maximal nitrogen loading rate of 0.6 g N l(-1) d(-1), the reactor presented ammonium and nitrite removal efficiencies of above 90%. In addition, a modified Stover-Kincannon model was applied to simulate and assess the performance of the Anammox reactor. The Stover-Kincannon model was appropriate for the description of the nitrogen removal in the reactor with the high regression coefficient values (R2 = 0.946) and low Theil's inequality coefficient (TIC) values (TIC < 0.3). The model results showed that the maximal N loading rate of the reactor should be 3.69 g N l(-1) d(-).
    Environmental Technology 05/2014; 35(9-12):1226-33. DOI:10.1080/09593330.2013.865084 · 1.56 Impact Factor
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    • "That concept, however, is not applicable for biofilm systems (Fux et al., 2004) because biofilms can sustain microorganisms with very different growth kinetics due to the undefined SRT and their distinct substrate gradients (Bryers, 2000); further also for combined PN/A SRT cannot be applied as sole selection criterion due to the significantly slower growth rate of the anammox biomass. The most practical approach to limit nitrite oxidation is considered to be reactor operation under oxygen limited conditions which favors growth of ammonium oxidizing bacteria versus nitrite oxidizing bacteria, as their oxygen affinity is higher (Blackburne et al., 2008; Wyffels et al., 2004) and combined with additionally competition for nitrite by the anammox bacteria. Within the last decade several technologies have been developed and successfully implemented in full scale, e.g. "
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    ABSTRACT: Partial nitritation/anammox (PN/A) has been one of the most innovative developments in biological wastewater treatment in recent years. With its discovery in the 1990s a completely new way of ammonium removal from wastewater became available. Over the past decade many technologies have been developed and studied for their applicability to the PN/A concept and several have made it into full-scale. With the perspective of reaching 100 full-scale installations in operation worldwide by 2014 this work presents a summary of PN/A technologies that have been successfully developed, implemented and optimized for high-strength ammonium wastewaters with low C:N ratios and elevated temperatures. The data revealed that more than 50% of all PN/A installations are sequencing batch reactors, 88% of all plants being operated as single-stage systems, and 75% for sidestream treatment of municipal wastewater. Additionally an in-depth survey of 14 full-scale installations was conducted to evaluate practical experiences and report on operational control and troubleshooting. Incoming solids, aeration control and nitrate built up were revealed as the main operational difficulties. The information provided gives a unique/new perspective throughout all the major technologies and discusses the remaining obstacles.
    Water Research 05/2014; 55:292–303. DOI:10.1016/j.watres.2014.02.032 · 5.53 Impact Factor
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    • "The SHARON process (Hellinga et al., 1998) relies on short sludge retention time (SRT) (1–1.5 d) and high temperatures (30–35 °C) to washout NOB from the system. Alternative approaches for nitrite build-up take advantage of the lower dissolved oxygen (DO) affinity of NOB (Wyffels et al., 2004) or their higher sensitivity towards free ammonia (FA) and/or free nitrous acid (FNA) (Ganigué et al., 2009; Qiao et al., 2010; Yamamoto et al., 2011). The SHARON process is conducted in a continuous stirred tank reactor (CSTR) configuration, where the maximum volumetric loading rate is limited by the maximum growth rate of AOB (Wyffels et al., 2004). "
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    ABSTRACT: The Anammox process allows a sustainable treatment of wastewater with high nitrogen content. Partial oxidation of ammonium to nitrite is a previous and crucial step. Given the variability on wastewater composition, the operation of sequencing batch reactors (SBR) for partial nitritation (PN) is very challenging. This work assessed the combined influence of influent characteristics and process loading rate. Simulation results showed that wastewater composition - Total nitrogen as ammonia (TNH) and total inorganic carbon (TIC) - as well as nitrogen loading rate (NLR) govern the outcomes of the reactor. A suitable effluent can be produced when treating wastewater with different ammonia levels, as long as the TIC:TNH influent molar ratio is around 1:1 and extreme NLR are avoided. The influent pH has a key impact on nitrite conversion by governing the CO(2)-bicarbonate-carbonate equilibrium. Finally, results showed that oxidation of biodegradable organic matter produces CO(2), which acidifies the media and limits process conversion.
    Bioresource Technology 02/2012; 111:62-9. DOI:10.1016/j.biortech.2012.01.183 · 4.49 Impact Factor
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