水中聚乙烯微塑料风化行为对混凝过程的影响

以地表水中丰度较高的聚乙烯（PE）微塑料作为研究对象，开展吸附和混凝试验，在解析PE微塑料对水中有机物吸附能力的基础上，用氙灯对PE微塑料进行光老化以模拟微塑料在自然条件下的风化行为，深入研究PE微塑料风化行为对混凝过程的影响。结果表明：粒度为50~200目的PE微塑料对有机物的吸附量为310~350 mg/g（以碳计），不存在显著的吸附性能差异。在混凝过程中，相较于未添加PE微塑料的情况，添加未风化的PE微塑料会降低有机物去除率，而添加风化PE微塑料则能明显提升有机物去除率。同时，混凝过程对风化PE微塑料的去除率高于未风化PE微塑料，表明PE微塑料的风化行为有利于其在混凝过程中被去除。根据混凝过程中絮体特征可知，PE微塑料的风化行为对形成絮体的尺寸影响极小，但能显著提高絮体的生长速度。

Effect of weathering behavior of polyethylene microplastics in water on coagulation process

Polyethylene (PE) microplastics with high abundance in surface water were used as the research object to conduct adsorption and coagulation experiments. Based on the study regarding the organic matter adsorption capacity of PE microplastics, the effect of weathering behavior of PE microplastics on the coagulation process was further explored by using photoaged PE microplastics with xenon lamp to simulate weathering behavior of microplastics under natural conditions. The results showed that PE microplastics with particle size 50-200 mesh could adsorb 310-350 mg/g (calculated by carbon) organic matter, indicating that the microplastic size would not significantly influence the adsorption performance of PE microplastics. In coagulation, compared with no PE microplastics conditions, the addition of unweathered PE microplastics was prone to decrease the organic matter removal rate, while the addition of weathered PE microplastics was able to obviously increase the removal efficiency of organic matter. Furthermore, the removal rate of weathered PE microplastics was remarkably higher than that of unweathered PE microplastics in coagulation, which suggested that the weathering behavior was beneficial to PE microplastics removal during the coagulation process. According to the floc properties in coagulation, it was notable that both unweathered and weathered PE microplastics would not influence floc average size in coagulation, but significantly increased the growth rate of flocs in this process.