摘要
In wastewater treatment plants(WWTPs),microplastics(MPs)are complex,especially with mixed domestic–industrial influents.Conventional random grab sampling can roughly depict the distribution and characteristics of MPs but can not accurately reflect their daily fluctuations.In this study,the concentration,shape,polymer type,size,and color of MPs were analyzed by micro-Raman spectroscopy(detection limit of 0.05 mm)throughout treatment stages of three mixed domestic–industrial WWTPs(W1,W2,and W3)in Wuxi City,China,and the daily fluctuations of MPs were also obtained by dense grab sampling within 24 h.For influent samples,the average MP concentration of 392.2 items/L in W1 with 10%industrial wastewater was much higher than those in W2(71.2 items/L with 10%industrial wastewater)and W3(38.3 items/L with 60%industrial wastewater).White polyethylene granules with a diameter less than 0.5 mm from plastic manufacturing were the most dominant MPs in the influent of W1,proving the key role of industrial sources in MPs pollution.In addition,the daily dense sampling results showed that MP concentration in W1 influent fluctuated widely between 29.1 items/L and 4617.6 items/L within a day.Finally,few MPs(less than 4.0 items/L)in these WWTPs effluents were attributed to the effective removal of wastewater treatment processes.Thus,further attention should be paid to regulating the primary sources of MPs.
基金
This work was supported by the Major Science and Technology Program forWater Pollution Control and Treatment(China)(No.2017ZX07302-001)
the Research Program for In-depth Treatment Technology Upgradation of theWuxi Urban Sewage Treatment Plant(China)(N20191003)
The authors also gratefully acknowledge the support of the Pre-research Fund of Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment(China)(No.XTCXSZ2020-2).
