Department of Civil and Environmental Engineering, Indian Institute of Technology Patna, Bihar, 801 106, India.
Department of Civil and Environmental Engineering, Indian Institute of Technology Patna, Bihar, 801 106, India.
J Environ Manage. 2023 Aug 15;340:118014. doi: 10.1016/j.jenvman.2023.118014. Epub 2023 Apr 28.
Microplastics (MPs) (plastic particles <5 mm) are globally acknowledged as a serious emerging micropollutant, which passes through various pathways in natural habitats and eventually ends up in our food chain. In this context, the present study critically reviews recent advances in MPs sampling and detection, occurrence, fate, and removal in wastewater treatment plants (WWTPs) by delineating their characteristics that manifest toxicity in the environment via effluent discharge. While there is currently no standard protocol in place, this work examined and compared the latest approaches adopted for improved sampling, sample processing, and characterization of MPs via fluorescence imaging and certified reference materials for method validation. MPs concentration from different sources in the WWTPs varies considerably ranging between 0.28 and 18285 MPs/L (raw wastewater), 0.004-750 MPs/L (effluent), and 0.00023-10380 MPs/kg (sludge). Assessment of MPs removal efficiency across different treatment stages in various in WWTPs has been performed and elucidated their removal mechanisms. The overall MPs removal efficiency in primary, secondary, and tertiary treatment stages in WWTPs reported to be around 57-99%, 78.1-99.4%, and 90-99.2%, respectively. Moreover, the review covers advanced treatment methods for removing MPs, including membrane bioreactors, coagulation/flocculation, ultrafiltration, rapid sand filtration, ozonation, disc filtration, and reverse osmosis, which have been found to be highly effective (>99%). Membrane bioreactors have been proclaimed to be the most reliable secondary treatment technique for MPs removal. Coagulation (92.2-95.7%) followed by ozonation (99.2%) as a tertiary treatment chain has been demonstrated to be the most efficient in removing MPs from secondary-treated wastewater effluent. Further, the review delineates the effect of different treatment stages on the physical and chemical characteristics of MPs, associated toxicity, and potential impact factors that can influence the MPs removal efficiency in WWTPs. Conclusively, the merits and demerits of advanced treatment techniques to mitigate MPs pollution from the wastewater system, research gaps, and future perspectives have been highlighted.
微塑料（MPs）（粒径<5 毫米）被全球公认为一种严重的新兴微污染物，它们通过自然栖息地的各种途径传播，最终进入我们的食物链。在这种情况下，本研究通过描述通过废水排放对环境表现出毒性的 MPs 的特征，批判性地回顾了 MPs 在污水处理厂（WWTP）中的采样和检测、出现、命运和去除方面的最新进展。虽然目前尚无标准协议，但本工作检查和比较了为改进采样、样品处理和 MPs 荧光成像以及用于方法验证的认证参考材料的特征而采用的最新方法。WWTP 中不同来源的 MPs 浓度差异很大，范围在 0.28 到 18285 MPs/L（原废水）、0.004 到 750 MPs/L（出水）和 0.00023 到 10380 MPs/kg（污泥）之间。已经对不同处理阶段在不同 WWTP 中的 MPs 去除效率进行了评估，并阐明了它们的去除机制。报告 WWTP 中初级、二级和三级处理阶段的 MPs 总去除效率分别约为 57-99%、78.1-99.4%和 90-99.2%。此外，本综述还涵盖了去除 MPs 的高级处理方法，包括膜生物反应器、混凝/絮凝、超滤、快速砂滤、臭氧氧化、盘式过滤和反渗透，这些方法已被证明非常有效（>99%）。膜生物反应器已被宣布为去除 MPs 的最可靠的二级处理技术。作为三级处理链的混凝（92.2-95.7%）随后是臭氧氧化（99.2%）已被证明是去除二级处理废水出水的 MPs 的最有效方法。此外，本综述还描述了不同处理阶段对 MPs 的物理化学特性、相关毒性以及可能影响 WWTP 中 MPs 去除效率的潜在影响因素的影响。最后，强调了先进处理技术减轻废水系统中 MPs 污染的优点和缺点、研究空白和未来展望。
