ABSTRACT

Wastewater treatment plants (WWTPs) have been identified as a source of microplastics, an emerging contaminant class of increasing concern, to the environment. Three WWTPs in the Canterbury region, New Zealand, were sampled bi-monthly from winter (June) to summer (December), to assess the variability of the abundance, morphology and polymer type of microplastics present over time. Microplastics were isolated from effluent via wet-sieving (300 μm and 1 mm) and wet peroxide oxidation (WPO) digest, and the polymer types determined using micro-Fourier-Transform Infrared Spectroscopy (μ-FTIR). Confirmed microplastics were detected at an average concentration of 1.3 ± 0.6 particles/L in effluent, with fragments comprising 58% of all morphotypes. Dominant polymer types detected were polyester, polyethylene, and polypropylene (26%, 22%, and 15%, respectively). The results of this study were comparable with those reported in international studies. An estimated 2.4 × 10⁵ microplastics enter the receiving coastal environment daily from the discharge of effluent from the three WWTPs studied. No trends in microplastic concentration, morphotype and polymer type were observed in effluent samples from each WWTP, suggesting a common and continual source of microplastics into WWTPs. Further sampling is required to identify the factors that determine the variability of microplastics in WWTP influents and effluents.

摘要

废水处理厂 (WWTP) 已被确定为微塑料的来源，微塑料是一种日益受到环境关注的新兴污染物类别。从冬季（六月）到夏季（十二月），每两个月对新西兰坎特伯雷地区的三个污水处理厂进行一次采样，以评估微塑料的丰度、形态和聚合物类型随时间的变化。通过湿筛（300 μm 和 1 mm）和湿式过氧化物氧化 (WPO) 消解法从废水中分离出微塑料，并使用微傅里叶变换红外光谱 (μ-FTIR) 确定聚合物类型。在污水中检测到的微塑料平均浓度为 1.3 ± 0.6 颗粒/升，其中碎片占所有形态类型的 58%。检测到的主要聚合物类型是聚酯、聚乙烯和聚丙烯（26%、22% 和 15%，分别）。这项研究的结果与国际研究报告的结果相当。估计 2.4 × 10^{每天有 5 种}微塑料通过所研究的三个污水处理厂的废水排放进入接收沿海环境。在每个污水处理厂的废水样品中没有观察到微塑料浓度、形态类型和聚合物类型的趋势，这表明污水处理厂中微塑料有一个共同且持续的来源。需要进一步采样以确定决定污水处理厂进水和出水中微塑料变化的因素。