Characterization and removal of microplastics in a sewage treatment plant from urban Nagpur, India

Sewage treatment plant (STP) acts as a potential source of microplastic contamination in the environment. The presence of microplastics in the sewage treatment plant is reported over the globe in varying concentrations. Hence, the current study is intended to evaluate the presence and abundance of microplastics occurring in sewage treatment plants in India. The samples were processed through digestion and density separation, followed by microscopic and polymer identification through Fourier transform infrared spectroscopy. Also, different wastewater parameters were studied to analyze their influence. High microplastic concentrations were detected in the influent (1860 +/- 265 MPs/L), which reduced by > 90%, to around 148 +/- 51 MPs/L in the effluent. The concentration of microplastics in sewage sludge was 830 MPs/kg. The prominent plastic types identified include low-density polyethylene, polypropylene, polyurethane, polyvinyl chloride, and rayon. The smaller particles prevail in the effluent, releasing around 30 billion particles per day to the environment. This suggests that the current STP is efficient in removing the majority of the particles, but considerations are needed to avoid the ecological risks associated.

Automated summary

Sewage treatment plants (STPs) contribute to the presence of microplastics in the environment, with varying concentrations reported worldwide. This study evaluated the abundance and presence of microplastics in Indian STPs. The results showed high concentrations of microplastics in the influent, but a significant reduction in the effluent. The main types of plastics identified were low-density polyethylene, polypropylene, polyurethane, polyvinyl chloride, and rayon. The study highlights the efficiency of the current STPs in removing microplastics but emphasizes the need to address ecological risks.