Key Laboratory of Karst Geological Resources and Environment (Guizhou University), Ministry of Education, Guiyang, Guizhou 550000, China.
Key Laboratory of Karst Geological Resources and Environment (Guizhou University), Ministry of Education, Guiyang, Guizhou 550000, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang, Guizhou, 550000, China.
Environ Pollut. 2023 Mar 1;320:121076. doi: 10.1016/j.envpol.2023.121076. Epub 2023 Jan 12.
Microplastic pollution threatens water systems worldwide. As one of the most important parts of city wastewater treatment, wastewater treatment plants are not only microplastics interception barriers but also emission sources. Water samples were collected from each sewage treatment plant stage and sludge from the sludge dewatering room. Microplastics were extracted using wet peroxide oxidation and flotation, and the abundance, size, shape, and polymer type of microplastics were detected. Basis on the results, the influence of each process on the removal rate and characteristics of microplastics under the same influent source was analysed. The influent microplastic concentration in this study was 32.5 ± 1.0 n/L, which rapidly decreased after treatment. The removal rates of the sequencing batch reactor activated sludge, cyclic activated sludge, and anaerobic anoxic oxic technologies were 73.0%, 75.6%, and 83.9%, respectively. Most microplastics were transported to the sludge, and the concentration of microplastics in dehydrated sludge was 27.2 ± 3.1 n/g. Microplastics removal occurred primarily during the primary and secondary stages. Disposal processes, settling time, and process design affected wastewater treatment plant microplastic removal rates at each stage. Significant differences in microplastic characteristics were observed at each stage, with the most abundant being fragment shaped, particle sizes of 30-100 μm, and black in colour. Sixteen polymer types were identified using a Raman spectrometer. The predominant polymers are polypropylene, polyethylene, and polyethylene terephthalate. This study demonstrates that optimising the process design of existing wastewater treatment plants is crucial for the prevention and control of microplastic pollution. It is suggested that the process settings of contemporary wastewater treatment plants should be studied in depth to develop a scientific foundation for avoiding and managing microplastic pollution in urban areas.
微塑料污染威胁着全世界的水系统。作为城市污水处理最重要的部分之一，污水处理厂不仅是微塑料的截留屏障，也是排放源。从每个污水处理厂的各个阶段采集水样，并从污泥脱水室采集污泥。使用湿过氧化物氧化和浮选法提取微塑料，并检测微塑料的丰度、尺寸、形状和聚合物类型。根据结果，分析了在相同进水源条件下，每个工艺对微塑料去除率和特性的影响。本研究中进水的微塑料浓度为 32.5 ± 1.0 n/L，处理后迅速下降。序批式活性污泥法、循环活性污泥法和厌氧缺氧好氧工艺的去除率分别为 73.0%、75.6%和 83.9%。大多数微塑料被输送到污泥中，脱水污泥中微塑料的浓度为 27.2 ± 3.1 n/g。微塑料去除主要发生在一级和二级处理阶段。处置工艺、沉降时间和工艺设计影响了每个阶段污水处理厂的微塑料去除率。在每个阶段都观察到微塑料特征存在显著差异，最丰富的是碎片形状，粒径为 30-100 μm，颜色为黑色。使用拉曼光谱仪鉴定了 16 种聚合物类型。主要的聚合物是聚丙烯、聚乙烯和聚对苯二甲酸乙二醇酯。本研究表明，优化现有污水处理厂的工艺设计对于预防和控制微塑料污染至关重要。建议深入研究当代污水处理厂的工艺设置，为避免和管理城市地区的微塑料污染提供科学依据。
