Microplastics (MPs) are described as plastic particles smaller than 5mm in size, which might pose serious threat on the aquatic organisms due to its slow degradation and small size. Apart from waste plastics, municipal effluent from wastewater treatment plant has been proposed a known source of MPs to enter in the aquatic environment. However, few studies focus on the abundance of MPs and their removal in wastewater treatment plant.
The Ecology Pollution Group in Wuhan Botanical Garden investigated the transfer and fate of MPs in one wastewater treatment plant of Wuhan City, the central of China.
The results indicated the removal rate of MPs during the whole treatment was 64.4%, and the microplastics removed were mostly transferred and stored into the sludge. Larger size fraction of MPs in the effluent was reduced compared to that in the influent due to a series of treatment process.
An interesting finding was that the ellipses seldom reported before were abundantly seen in the influent with a percentage of 4.4%, but not observed in the effluent. One part of them was stored into sludge, while the other was degraded during the whole treatment process.
This study shows that there is still high abundance of microplastic in the effluent of wastewater treatment plant, thus much emphasis should be exerted on the removal rate of microplastic, escaping the potential pollution on aquatic environment.
This study was supported by Funding Project of Sino-Africa Joint Research Center, Chinese Academy of Sciences, and results were published in Chemical Engineering Journal with the title of "Transfer and fate of microplastics during the conventional activated sludge process in one wastewater treatment plant of China".