Bunse Philipp, Orschler Laura, Agrawal Shelesh, Lackner Susanne
Department of Civil and Environmental Engineering Sciences, Institute IWAR, Chair of Wastewater Engineering, Technical University of Darmstadt, Germany.
Water Res X. 2020 Sep 3;9:100066. doi: 10.1016/j.wroa.2020.100066. eCollection 2020 Dec 1.
This study investigated the potential of Membrane-Aerated Biofilm Reactors (MABRs) for mainstream nitrogen removal via partial nitration/anaerobic ammonium oxidation (anammox). Four laboratory-scale MABRs were operated with real municipal wastewater characterized by low concentrations of nitrogen (varying between 31 and 120 mg-NH-N L) and the presence of biodegradable organic carbon (soluble COD (sCOD) between 7 and 230 mg-O L). Two reactors were operated with different aeration strategies (intermittent vs. continuous), the other two with differences in biomass retention (recirculation or removal of detached biomass). Keeping a constant HRT caused instabilities due to difficulties with setting the optimal oxygen flux for the respective surface loadings (1.6-6 g-NH-N m d). Operating the MABRs with a constant surface loading (2 g-NH-N m d) resulted in higher and more stable total nitrogen (TN) removal independent of the aeration strategy. The intermittently aerated MABR improved from an average TN removal of 23%-69%, the continuously aerated MABR from 20% to 50% TN removal. Independent of the feeding strategy, the continuously aerated reactor removed slightly more ammonium (80-95%) compared to the intermittently aerated reactor (74-93%). Limiting the oxygen supply by intermittent aeration proofed successful to favor partial nitritation and anammox. Continuous aeration did not achieve stable suppression of nitrite oxidizing bacteria (NOB). Of the removed ammonium, approx. 26% were left in the effluent as nitrate (only 10% with intermittent aeration). Recirculation of the detached biomass resulted in reattachment onto the biofilm or membrane surface. This recirculation led to significantly higher biomass retention times and thus to better performance. Removing detached biofilm from the reactor caused a slightly lower TN removal of 33% compared to 45% with reattachment, while average ammonium removal was 58% compared to 63%, respectively. Scouring events had a significant impact on the overall operation, resulting in short term losses of TN removal capacities of 50-100%. The microbial community composition was different depending on the aeration strategy and biomass retention. The continuously aerated reactor contained significantly more AOB than the intermittently aerated MABR. The reactor with biomass retention contained less ammonium oxidizing bacteria (AOB), compared to the reactor with low biomass retention. In all MABRs, anammox bacteria established in the biofilm after an initial drop in abundance.
本研究调查了膜曝气生物膜反应器（MABR）通过部分硝化/厌氧氨氧化（anammox）实现主流氮去除的潜力。四个实验室规模的MABR以实际城市污水运行，其特点是氮浓度低（在31至120mg-NH₄-N/L之间变化）且存在可生物降解的有机碳（可溶性化学需氧量（sCOD）在7至230mg-O/L之间）。两个反应器采用不同的曝气策略（间歇曝气与连续曝气）运行，另外两个在生物量保留方面存在差异（分离生物量的再循环或去除）。由于难以针对各自的表面负荷（1.6 - 6g-NH₄-N/m²·d）设定最佳氧通量，保持恒定的水力停留时间（HRT）会导致运行不稳定。以恒定表面负荷（2g-NH₄-N/m²·d）运行MABR可实现更高且更稳定的总氮（TN）去除，且与曝气策略无关。间歇曝气的MABR的平均TN去除率从23%提高到69%，连续曝气的MABR从20%提高到50%。与间歇曝气的反应器（74 - 93%）相比，无论进水策略如何，连续曝气的反应器去除的铵略多（80 - 95%）。通过间歇曝气限制氧气供应被证明有利于部分亚硝化和anammox。连续曝气未能实现对亚硝酸盐氧化细菌（NOB）的稳定抑制。在去除的铵中，约26%以硝酸盐形式留在流出物中（间歇曝气时仅为10%）。分离生物量的再循环导致其重新附着在生物膜或膜表面。这种再循环导致生物量保留时间显著延长，从而性能更好。与再附着时45%的TN去除率相比，从反应器中去除分离的生物膜导致TN去除率略低，为33%，而平均铵去除率分别为58%和63%。冲刷事件对整体运行有显著影响，导致TN去除能力短期损失50 - 100%。微生物群落组成因曝气策略和生物量保留情况而异。连续曝气的反应器中氨氧化细菌（AOB）的含量明显高于间歇曝气的MABR。与生物量保留低的反应器相比，生物量保留的反应器中氨氧化细菌（AOB）较少。在所有MABR中，anammox细菌在丰度最初下降后在生物膜中定殖。
