微塑料在污水处理过程中的演变与归宿

Evolution and Fate of Microplastics in Sewage Treatment

微塑料(粒径<5 mm)因生产、生活使用废弃后所产生,分原生与次生两种形式。按不同检测粒径分级,原污水中微塑料数量不一,但每m3至少达千粒至十万粒以上,且多属于生物难降解成分。微塑料进入污水处理厂后主要被一级处理吸附截留去除;二级处理亦以吸附去除为主,但作用不大;三级处理可通过膜截留方式具有一定去除作用。污水一、二级处理对微塑料的总去除率约为80%,出水残留微塑料(≤20%)则进入水环境,也是目前水圈中微塑料迁移、累积的重要来源。环境中的微塑料可通过饮用水、食盐、海鲜等方式进入人体,对人类健康形成各种潜在危害。为此,介绍了污水中微塑料的来源及危害,总结了检测水中微塑料的方法,分析微塑料在污水处理过程中的迁移转化规律,阐述微塑料之环境归宿以及防范策略。

Microplastics ( size < 5 mm) are produced due to daily discard from both daily life and industry production, in which there are two forms: primary and secondary microplastics. Numbers of microplastics vary a lot due to different testing particle sizes, and there are at least 1 000 to 100 000 n/m^3 in raw sewage, most of which are unbiodegradable. Microplastics were mainly removed by adsorption in the primary treatment facilities;some microplastics could be adsorbed in the secondary treatment process, but the role of the secondary treatment was not great;the membrane interception method in the tertiary treatment ( membrane and/or filtration) could effectively remove microplastics. The average removing efficiency of microplastics via both primary and secondary treatment was around 80%, the residue (≤20%) of microplastics in the effluent would enter into the water environment, which was a major source of evolution and accumulation in the hydrosphere. Microplastics in the environment could be taken up by the human beings through drinking water, salt, seafood, etc. For this reason, the sources and hazards of microplastics were reviewed;and detecting methods in water/wastewater were summarized;evolution patterns were analyzed;fate in the environment and preventive measures into both products and the environment were elucidated.