School of Bio-Chemical Engineering and Technology, Thammasat University, Thailand.
Waste Manag Res. 2021 May;39(5):754-761. doi: 10.1177/0734242X20982055. Epub 2021 Jan 6.
Plastic waste has become a global environmental concern. One type of plastic waste is microplastics (MPs), which can spread easily in the environment. Wastewater effluent is one of the land-based sources of MPs. This study investigates the amount of microplastic (MP) pollution in an urban wastewater treatment plant (WWTP) in Thailand. Water samples were collected and examined to find the types, morphology and sources of MPs. Wastewater was filtered through a set of sieves ranging from 5 mm to 0.05 mm. Sludge samples were also collected to find the potential risk from the application of dried sewage sludge. Fourier-transform infrared spectroscopy (FTIR) was used to confirm the types of MPs. The amount of MPs in the influent was 26.6 ± 11.8 MPs/L. More than one-third of MP particles were removed after a grit trap, followed by 14.24% removal in the secondary treatment. If the peak flow rate of the WWTP is reached, 2.32 × 10 MP particles can be released daily. The amount of MPs in a sludge sample was 8.12 ± 0.28 × 10 particles/kg dry weight. Dry sludge is one of the potential sources of MP contamination in agricultural soil. Most MPs in the liquid fraction and sludge sample were fibres. Results from FTIR analysis showed that the major types of MPs in the WWTP were polyester fibres, followed by polypropylene, polyethylene, silicone polymer and polystyrene. This finding indicates that a conventional WWTP may act as a path by which MPs enter the environment.
塑料废物已成为全球环境关注的问题。其中一种塑料废物是微塑料（MPs），它们很容易在环境中扩散。废水是 MPs 的陆地来源之一。本研究调查了泰国一个城市废水处理厂（WWTP）中的微塑料（MP）污染程度。采集水样并进行检查，以确定 MPs 的类型、形态和来源。废水通过一组从 5 毫米到 0.05 毫米的筛子进行过滤。还收集了污泥样本，以发现干燥的污水污泥应用的潜在风险。傅里叶变换红外光谱（FTIR）用于确认 MPs 的类型。进水口的 MPs 含量为 26.6±11.8 MPs/L。经过砾石阱后，超过三分之一的 MPs 颗粒被去除，随后在二级处理中去除了 14.24%。如果达到 WWTP 的高峰流量，每天可释放 2.32×10 MPs 颗粒。污泥样本中的 MPs 数量为 8.12±0.28×10 颗粒/公斤干重。干污泥是农业土壤中 MP 污染的潜在来源之一。液体部分和污泥样本中的大多数 MPs 是纤维。FTIR 分析结果表明，WWTP 中的主要 MPs 类型是聚酯纤维，其次是聚丙烯、聚乙烯、硅酮聚合物和聚苯乙烯。这一发现表明，传统的 WWTP 可能是 MPs 进入环境的途径之一。
