Distribution and occurrence of microplastics in wastewater treatment plants

Microplastic pollution is an alarming problem into aquatic environment. Wastewater treatment plants (WWTPs) with applied technologies are strictly interested in the technical challenges with budget calculations and sustainable development without contaminants. WWTPs are suspected as potential sources discharging microplastics (MPs) into the environment. This study investigated the distribution and occurrence of MPs in influent and effluent of three typical industrial wastewater treatment plants (WWTPs) named HoaCam WWTP (HC WWTP), DaNang WWTP (DN WWTP), and HoaKhanh WWTP (HK WWTP) in Danang city, Vietnam. The results showed that the abundance of MPs total is 183–443 particles/L and 138–340 particles/L in the influent and the effluent. The average MPs removal efficiency obtained 25.5%, 21.8% and 25.3% at HC, DN and HK of three WWTPs, respectively. Hence, the average loading capacity of MPs discharged to recipient sources is 3.8 × 107, 8.3 × 107 and 1.5 × 109 particles per day in the HC, DN, HK WWTPs, respectively. The majority of MPs identified in this study included a profile of size, shape type, color and chemical compositions of MPs. The sizes of MPs highly varied from 1.6 to 5000μm with the abundant MPs types of fiber and fragment in both the influent and the effluent. In addition, the colors of MPs such as yellow, white, blue and black are presented. Using Fourier Transform Infrared spectroscopy (FTIR), the main polymer compositions of MPs included polyethylene terephthalate (PET), polyethylene (PE), nylon and polyvinyl chloride (PVC) were determined in three WWTPs.