Department of Environmental Engineering, Faculty of Engineering, Chulalongkorn University, 254 Phayathai road, Wangmai, Pathumwan, Bangkok, 10330, Thailand.
Environmental Research Institute, Chulalongkorn University, Bangkok, Thailand.
Environ Sci Pollut Res Int. 2020 May;27(15):18557-18564. doi: 10.1007/s11356-020-08265-7. Epub 2020 Mar 20.
Municipal wastewater treatment plants (WWTPs) have been identified as a key source of microplastics (MPs) release into rivers and oceans. Varied extents of MPs pollution have been observed at different WWTPs with limited information in Thailand. This research aimed to study the occurrence of MPs in municipal WWTPs in Thailand by measuring MPs of three WWTPs which employ different treatment process. The WWTPs were selected to represent MP pollution from urbanized and suburbanized areas with different treatment set-ups, i.e., sequence batch reactor (WWTP-A), oxidation ditch (WWTP-B), and conventional activated sludge (WWTP-C). Water and sludge sampling was performed at the inlet and outlet of primary and secondary treatment units. The results indicate that the average MPs removal efficiency of the WWTPs was ca. 84%, with the aeration tank as the main removal unit by transferring MPs from the water phase to sludge. Primary treatment comprising of screening and grit chambers could not remove MPs effectively. Most of the MPs observed in the WWTPs were fibers (32-57%), mostly made of polyester, polyethylene, polyacrylate, and polypropylene. From these results, it is suggested to implement tertiary treatment options to improve MPs removal efficiency in WWTPs, and to apply post-treatment to the WWTPs' raw sludge to prevent the MPs' release into the environment when the sludge is applied to agricultural land.
城市污水处理厂（WWTP）已被确定为将微塑料（MPs）释放到河流和海洋中的关键来源。在泰国，有限的信息表明不同的 WWTP 存在不同程度的 MPs 污染。本研究旨在通过测量采用不同处理工艺的三个 WWTP 中的 MPs 来研究泰国城市 WWTP 中 MPs 的发生情况。选择 WWTP 来代表来自城市化和郊区化地区的 MP 污染，其处理设置不同，即序批式反应器（WWTP-A）、氧化沟（WWTP-B）和传统活性污泥（WWTP-C）。在一级和二级处理单元的进出口处进行了水和污泥采样。结果表明，WWTP 的 MPs 去除效率平均约为 84%，曝气池是通过将 MPs 从水相向污泥转移来主要去除单元。包括筛选和格栅室在内的一级处理不能有效地去除 MPs。在 WWTP 中观察到的大多数 MPs 是纤维（32-57%），主要由聚酯、聚乙烯、聚丙烯酸酯和聚丙烯制成。根据这些结果，建议在 WWTP 中实施三级处理选项以提高 MPs 的去除效率，并对 WWTP 的原始污泥进行后处理，以防止在将污泥施用于农田时 MPs 释放到环境中。
