Department of Energy, Environment and Climate Change, School of Environment, Resources and Development, Asian Institute of Technology, P.O. Box 4, Klong Luang, Pathumthani 12120, Thailand.
Department of Energy, Environment and Climate Change, School of Environment, Resources and Development, Asian Institute of Technology, P.O. Box 4, Klong Luang, Pathumthani 12120, Thailand.
Water Res. 2021 Jan 1;188:116547. doi: 10.1016/j.watres.2020.116547. Epub 2020 Oct 21.
Membrane bioreactor (MBR) is an advantageous technology for wastewater treatment. However, efficient nutrient removal and membrane fouling mitigation remain major challenges in its applications. In this study, an electroconductive moving bed membrane bioreactor (EcMB-MBR) was proposed for simultaneous removal of organics and nutrients from domestic wastewater. The EcMB-MBR was composed of a submerged MBR, filled with electrodes and free-floating conductive media. Conductive media were introduced to reduce energy consumption in an electrochemical MBR, to improve nitrogen removal, and to mitigate membrane fouling. The results showed that COD, total nitrogen, and total phosphorus removal was up to 97.1 ± 1.4%, 88.8 ± 4.2%, and 99.0 ± 0.9%, respectively, in comparison with those of 93.4 ± 1.5%, 65.2 ± 5.3%, and 20.4 ± 11.3% in a conventional submerged MBR. Meanwhile, a total membrane resistance reduction of 26.7% was obtained in the EcMB-MBR. The optimized operating condition was determined at an intermittent electricity exposure time of 10 min-ON/10 min-OFF, and a direct current density of 15 A/m. The interactions between electric current and conductive media were explored to understand the working mechanism in this proposed system. The conductive media reduced 21% of the electrical resistivity in the mixed liquor at a selected packing density of 0.20 (v/v). The combination of electrochemical process and conductive media specially enhanced the reduction of nitrate-nitrogen (NO-N) through hybrid bio-electrochemical denitrification processes. These mechanisms involved with electrochemically assisted autotrophic denitrification by autotrophic denitrifying bacteria. As a result, 5.2% of NO-N remained in the effluent of EcMB-MBR in comparison with that of 29.5% in the MBR. Membrane fouling was minimized via both mechanical scouring and electrochemical decomposition/precipitation of organic/particulate foulants. Furthermore, a preliminary cost analysis indicated that an additional operating cost of 0.081 USD/m, accounting for 10 - 30% increment of the operating cost of a conventional MBR, was needed to enhance the nitrogen and phosphorus removal correspondingly in the EcMB-MBR.
膜生物反应器（MBR）是一种用于废水处理的优势技术。然而，高效地去除营养物质和减轻膜污染仍然是其应用中的主要挑战。在这项研究中，提出了一种用于同时去除生活污水中有机物和营养物质的导电移动床膜生物反应器（EcMB-MBR）。EcMB-MBR 由浸没式 MBR 组成，其中填充有电极和自由浮动的导电介质。引入导电介质是为了降低电化学 MBR 的能耗，提高脱氮效率并减轻膜污染。结果表明，与传统的浸没式 MBR 中的 93.4 ± 1.5%、65.2 ± 5.3%和 20.4 ± 11.3%相比，COD、总氮和总磷的去除率分别高达 97.1 ± 1.4%、88.8 ± 4.2%和 99.0 ± 0.9%。同时，在 EcMB-MBR 中获得了 26.7%的总膜阻力降低。在 EcMB-MBR 中确定了最佳操作条件为间歇通电时间 10 min-ON/10 min-OFF，直流密度为 15 A/m。探索了电流与导电介质之间的相互作用，以了解该系统中的工作机制。在选定的填充密度为 0.20（v/v）时，导电介质将混合液中的电阻率降低了 21%。电化学过程和导电介质的结合特别增强了通过混合生物电化学反硝化过程对硝酸盐氮（NO-N）的还原。这些机制涉及通过自养脱氮细菌进行电化学辅助自养反硝化。结果，与 MBR 中的 29.5%相比，EcMB-MBR 中的出水中仍保留了 5.2%的 NO-N。通过机械冲刷和有机/颗粒污染物的电化学分解/沉淀来最小化膜污染。此外，初步的成本分析表明，需要额外的运行成本 0.081 美元/m，占传统 MBR 运行成本的 10-30%的增量，以相应地提高 EcMB-MBR 中的氮磷去除效率。
