Abstract:

Polyester fiber is an important source of microplastics in wastewater treatment plants, but the effect of polyester fiber on wastewater biological treatment is not clear. In this study, the response of polyester fiber microplastics with different concentrations (0, 10mg/L, 1000mg/L) of 1mm in length and 20µm in diameter to the reactor performance and microbial community structure was investigated in laboratory-scale sequencing batch reactor (SBR). The results showed that polyester fiber microplastics accumulated continuously in the sludge, but the treatment performance of the reactor was not significantly affected, with high purification capacity. At the same time, the continuous exposure of polyester fiber microplastics made the sludge settling performance worse and inhibited the secretion of extracellular polymeric substances (EPS). Under the stress of high concentration of polyester fiber microplastics, the abundance and diversity of sludge microbial community increased. Dokdonella was the most abundant denitrifying bacteria in activated sludge, and the relative abundance of denitrifying bacteria increased with the increase of polyester fiber microplastic concentration. This study showed that filamentous polyester fiber microplastics had no significant effect on the biological treatment performance of sewage, but had certain selectivity to sludge microbial community in a certain period.

Key words: sequencing batch reactor, polyester fiber, microplastics, extracellular polymeric substances, microbial community

摘要：

聚酯纤维是污水处理厂中微塑料的一个重要来源，但聚酯纤维对废水生物处理的影响尚不清楚。本研究采用实验室规模序批式反应器（sequencing batch reactor，SBR）处理模拟洗衣废水，考察不同浓度（0、10mg/L、1000mg/L），长1mm、直径20µm的聚酯纤维微塑料对反应器性能和微生物群落结构的响应。结果表明，聚酯纤维微塑料在污泥中不断积累，但反应器的处理性能未受到明显影响，具有较高的净化能力。同时，聚酯纤维微塑料的持续暴露使得污泥的沉降性能变差，并抑制了胞外聚合物（extracellular polymeric substances，EPS）的分泌。高浓度聚酯纤维微塑料胁迫下，污泥微生物群落的丰度和多样性增加。独岛菌属（Dokdonella）是活性污泥中相对丰度最高的脱氮菌属，随着聚酯纤维微塑料浓度的增加，反硝化菌属相对丰度也增加。本研究表明，在一定时期内丝状类聚酯纤维微塑料对污水生物处理性能的影响不显著，但对污泥微生物群落有一定的选择性。

关键词: 序批式反应器, 聚酯纤维, 微塑料, 胞外聚合物, 微生物群落