Fan Linhua, Mohseni Arash, Schmidt Jonathan, Evans Ben, Murdoch Ben, Gao Li
School of Engineering and WETT Research Centre, RMIT University, Melbourne, Victoria 3001, Australia.
School of Engineering and WETT Research Centre, RMIT University, Melbourne, Victoria 3001, Australia.
Sci Total Environ. 2023 Jun 10;876:162714. doi: 10.1016/j.scitotenv.2023.162714. Epub 2023 Mar 11.
Municipal wastewater treatment plants act as a sink, but also are a source of microplastics in the environment. A conventional wastewater lagoon system and an activated sludge (AS)-lagoon system in Victoria (Australia) were investigated through a two-year sampling program to understand the fate and transport of MP in such treatment processes. The abundance (>25 μm) and characteristics (size, shape, and colour) of the microplastics present in the various wastewater streams were determined. The mean values of MP in the influent of the two plants were 55.3 ± 38.4 and 42.5 ± 20.1 MP/L, respectively. The dominant MP size of influent and final effluent was <500 μm, with 25-200 μm accounting for >65 % of the total MP; synthetic fibres were the dominant MP in all wastewater streams. Influent MP concentration was significantly higher in summer than in other seasons for both systems, which was related to the lower plant inflow due to less stormwater entering the sewer during summer. The promising MP removal capability of the lagoon system (97 %) was attributed to its lengthy wastewater detention time (total HRT >250 days, including the storage lagoons) that would allow effective separation of MP from the water column via various physical and biological pathways. For the AS-lagoon system, the high MP reduction efficiency (98.4 %) was attributed to the post-secondary treatment of the wastewater with the lagoon system, in which MP was further removed during the month-long detention in the lagoons. The results indicated the potential of such low-energy and low-cost wastewater treatment systems for MP control.
城市污水处理厂既是微塑料的汇，也是环境中微塑料的一个来源。通过一项为期两年的采样计划，对澳大利亚维多利亚州的一个传统废水泻湖系统和一个活性污泥 - 泻湖系统进行了调查，以了解微塑料在这种处理过程中的归宿和迁移。测定了各种废水流中存在的微塑料的丰度（>25μm）和特性（尺寸、形状和颜色）。这两个工厂进水的微塑料平均值分别为55.3±38.4和42.5±20.1个/升。进水和最终出水的微塑料主要尺寸<500μm，其中25 - 200μm占微塑料总量的>65%；合成纤维是所有废水流中的主要微塑料类型。两个系统夏季的进水微塑料浓度均显著高于其他季节，这与夏季进入下水道的雨水较少导致工厂进水量较低有关。泻湖系统有前景的微塑料去除能力（97%）归因于其较长的废水停留时间（总水力停留时间>250天，包括储存泻湖），这将允许通过各种物理和生物途径使微塑料从水柱中有效分离。对于活性污泥 - 泻湖系统，较高的微塑料去除效率（98.4%）归因于废水在泻湖系统中的二级后处理，其中微塑料在泻湖中长达一个月的停留期间被进一步去除。结果表明了这种低能耗和低成本废水处理系统在控制微塑料方面的潜力。
