Department of Environmental Engineering, Faculty of Engineering, Chulalongkorn University, 254 Phyathai Rd., Wangmai, Pathumwan, Bangkok 10330, Thailand.
Department of Environmental Engineering, Faculty of Engineering, Chulalongkorn University, 254 Phyathai Rd., Wangmai, Pathumwan, Bangkok 10330, Thailand; Research Network of NANOTEC-CU (RNN) on Environment, Chulalongkorn University, Bangkok 10330, Thailand.
J Hazard Mater. 2021 Jun 5;411:124991. doi: 10.1016/j.jhazmat.2020.124991. Epub 2020 Dec 30.
Issues associated with accumulating microplastic (MP) in sewage sludge during wastewater treatment in a membrane bioreactor (MBR) system have not been studied in detail. Here, we investigated the microplastic's effects on floc characteristics, microbial community compositions, and fouling behavior inside sequencing-batch MBRs. MBRs were operated with 0, 7, 15, and 75 MPs/L of feed for 124-days. Results indicated that MP presence decreased sludge floc size, floc hydrophobicity, and extracellular polymeric substance (EPS) molecular size, and increased EPS concentration and the floc's negative zeta potential. These results were attributed to the facilitation of divalent cation (Ca and Mg) uptake by MPs that weakened ion-bridging interactions within the sludge flocs. MPs accumulation slightly affected microbial structure and diversity. Relative abundances of dominant phyla, Actinobacteria, also decreased substantially. MPs also acted like a scouring material on membrane surfaces, inducing transformation of matured biofilm structures where protein content was substantially lower than nucleic acid content, in contrast to the control. Overall, MPs' negative effects on sludge flocs were counteracted by their scouring effect; consequently, SB-MBRs operated up to 4 months did not suffer from severe cake fouling, compared to control.
在膜生物反应器（MBR）系统中处理废水时，污水污泥中积累微塑料（MP）的相关问题尚未得到详细研究。在这里，我们研究了微塑料对絮体特性、微生物群落组成和序批式 MBR 内部结垢行为的影响。MBR 以 0、7、15 和 75 MPs/L 的进料运行了 124 天。结果表明，MP 的存在降低了污泥絮体的粒径、疏水性和胞外聚合物（EPS）分子大小，增加了 EPS 浓度和絮体的负 ζ 电位。这些结果归因于 MPs 促进了二价阳离子（Ca 和 Mg）的摄取，从而削弱了污泥絮体内部的离子桥接相互作用。MP 的积累对微生物结构和多样性的影响较小。优势菌门放线菌的相对丰度也大幅下降。MP 还对膜表面起到了冲刷作用，诱导成熟生物膜结构的转化，其中蛋白质含量明显低于核酸含量，与对照形成对比。总的来说，MP 对污泥絮体的负面影响被其冲刷作用所抵消；因此，与对照相比，运行长达 4 个月的 SB-MBR 并未遭受严重的结垢。
