Nitrogen removal and microbial community in a Simultaneous Nitrification and Denitrification Moving Bed Membrane Bioreactor (SND-MBMBR)

This study aimed to evaluate the nitrogen and organic matter removal, and the main microorganisms involved in this process, in a submerged membrane bioreactor with biofilm (SMBR-BF) operated in different concentrations of dissolved oxygen (DO) and under specific conditions for simultaneous nitrification and denitrification (SND). The SMBR-BF was operated in two phases characterized by the DO concentrations whose DO average concentrations were 2,3 ± 0,2 mg O2/L e 0,9 ± 0,3 mg O2/L for the phase I and II respectively. The system operated under the average flow of 22 ± 4 e 16 ± 1 L.h-1 in the phase I and II, respectively. It got elevated efficiency in turbidity removal, about 99 ± 1% for both phases. The average removal for COD and BDO5 was always over 95% ± 1, in any phase and conditions of the operation. The OD concentration influenced significantly the process of conversion of total nitrogen (TN), since in the Phase I, the removal was 33 ± 8 %, while the average removal in the Phase II was 74 ± 1%. There was stability in the ammoniacal nitrogen removal in both phases on similar percentages of 90 ± 2%. On the other hand, the molecular biology outcomes have demonstrated that the abundance and the dynamics of the total of bacteria, AOB, NOB and denitrifyings (Thiothrix, Comamonas, Rhodobacter, Mycobacterium, Thermomonas, Sphingobium, Sphigopyxis, Pseudoxanthomonas, Nitrospira and, Novosphingobium) was alike as in the suspended biomass as in the biolfilm on SMBR-BF system. It may be concluded that the reduction of DO concentration influenced the nitrogen removal, without changing the efficiency of organic matter elimination and the bacterial communities, whether the system is operated in SND configuration or in DO conditions previously exposed.

本研究旨在评估带生物膜浸没式膜生物反应器（submerged membrane bioreactor with biofilm，SMBR-BF）在不同溶解氧（dissolved oxygen，DO）浓度、同步硝化反硝化（simultaneous nitrification and denitrification，SND）特定工况下的氮与有机物去除效果，以及该过程涉及的主要微生物类群。该SMBR-BF分为两个运行阶段，阶段I与阶段II的平均溶解氧浓度分别为2.3±0.2 mg O₂/L和0.9±0.3 mg O₂/L。系统在阶段I与阶段II的平均进水流量分别为22±4 L·h⁻¹和16±1 L·h⁻¹。两个阶段的浊度去除效率均高达99±1%，表现优异。COD与5日生化需氧量（Biochemical Oxygen Demand，BOD₅，原文笔误为BDO5）的平均去除率在所有运行阶段与工况下均稳定维持在95%±1%以上。溶解氧浓度对总氮（total nitrogen，TN）的转化过程具有显著影响：阶段I的总氮去除率为33±8%，而阶段II的平均总氮去除率可达74±1%。两个阶段的氨氮去除率均稳定在90±2%的相近水平。另一方面，分子生物学检测结果表明，SMBR-BF系统中悬浮态微生物与附着态生物膜内的总细菌、氨氧化细菌（Ammonia Oxidizing Bacteria，AOB）、亚硝酸盐氧化细菌（Nitrite Oxidizing Bacteria，NOB）以及反硝化菌（包括丝硫细菌属*Thiothrix*、丛毛单胞菌属*Comamonas*、红杆菌属*Rhodobacter*、分枝杆菌属*Mycobacterium*、热单胞菌属*Thermomonas*、鞘氨醇单胞菌属*Sphingobium*、*Sphigopyxis*、假黄色单胞菌属*Pseudoxanthomonas*、硝化螺菌属*Nitrospira*以及新鞘氨醇杆菌属*Novosphingobium*）的丰度与群落动态均无显著差异。综上可得出结论：降低溶解氧浓度可提升系统的氮去除效果，且无论系统以同步硝化反硝化模式运行还是采用前述溶解氧工况，均不会改变有机物去除效率与细菌群落结构。