College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310012, PR China.
Sci Total Environ. 2022 Feb 1;806(Pt 1):150545. doi: 10.1016/j.scitotenv.2021.150545. Epub 2021 Sep 25.
Microplastics (MPs) are the emerging pollutants in the fresh water and have been found in the drinking water. Drinking water treatment plant (DWTP) is an important barrier to ensure the safety and quality of drinking water, so their effectiveness in removing MPs needs to be evaluated and optimized. In this paper, the abundance, characteristics and removal performance of 5 μm-5 mm granular MPs and 100 μm-5 mm fibrous MPs in the effluent of each water treatment unit in a DWTP in China were analyzed. The results show that only 80.96% of MPs ≤ 20 μm, accounting for more than 98% in the raw water, could be removed in the DWTP, while over 99% of the removal efficiency could be achieved for MPs > 20 μm. Coagulation-sedimentation and micro-flocculation combined with sand filtration couldn't effectively remove the granular MPs ≤ 20 μm (42.8% and 25.8%, respectively), but biological activated carbon (BAC) filtration was prone to remove this part (63.8%). Significant increases of granular MPs ≤ 20 μm were observed in the effluents of biological treatment (+149.6%) and ozonation (+13.8%). According to the variation in separate MPs' size distribution, the increases in MPs were attributed to the fragmentation of MPs, on which ozonation showed a remarkable effect. The ozonation might accelerate the aging and embrittlement of MPs, and then external stresses could further break them into smaller pieces, which eventually lead to an increase in MPs. To deal with the stubborn part and fragmentation of MPs in water, the removal ability of DWTP for MPs ≤ 20 μm needs to be improved. This study provides a detailed proof for the fate of MPs in the DWTP, and the results indicate that the fragmentation of MPs and the removal rate of MPs ≤ 20 μm should draw more attention in the DWTP.
微塑料（MPs）是淡水中新兴的污染物，已在饮用水中被发现。饮用水处理厂（DWTP）是确保饮用水安全和质量的重要屏障，因此需要评估和优化其去除 MPs 的效果。本文分析了中国某 DWTP 中各水处理单元出水中 5μm-5mm 颗粒 MPs 和 100μm-5mm 纤维 MPs 的丰度、特征和去除性能。结果表明，DWTP 只能去除 80.96%的≤20μm MPs，而在原水中，超过 98%的 MPs 可以被去除；而对于>20μm 的 MPs，去除效率超过 99%。混凝沉淀和微絮凝联合砂滤无法有效去除≤20μm 的颗粒 MPs（分别为 42.8%和 25.8%），但生物活性炭（BAC）过滤易于去除这部分 MPs（63.8%）。生物处理（+149.6%）和臭氧氧化（+13.8%）出水中观察到≤20μm 的颗粒 MPs 显著增加。根据 MPs 单独的尺寸分布变化，MPs 的增加归因于 MPs 的碎片化，臭氧氧化对此显示出显著效果。臭氧氧化可能会加速 MPs 的老化和脆化，然后外部应力会进一步将其破碎成更小的碎片，最终导致 MPs 的增加。为了处理水中顽固的 MPs 部分和碎片化，DWTP 对 MPs 的去除能力需要提高。本研究为 DWTP 中 MPs 的命运提供了详细的证据，结果表明，DWTP 中应更加关注 MPs 的碎片化和去除率<20μm 的 MPs。
