Quantitative analysis of microplastics in wastewater during selected treatment processes

Microplastics are plastic particles with a diameter of 1 μm–5 mm. In recent decades, contamination by plastic microparticles has become a serious environmental problem of a global nature. Wastewater treatment plants (WWTPs) are recognized as an important source of these micropollutants in surface waters – conventional methods of wastewater treatment do not completely remove plastic microparticles. The present research aimed to evaluate quantity and quality as well as estimate the removal efficiency of microplastics in the large and medium WWTP. The research carried out in two WWTPs (large and medium) showed the presence of microparticles of plastics in various forms – microfragments of foil, microfibers, and microgranules. The total concentration of microplastics in the grit chamber was 4,700–7,200 particles/m³ in the medium WWTP and 2,140–2,220 particles/m³ in the large one. In effluent, the concentration was not exceeded 600 and 780 particles/m³, respectively. Both WWTPs showed high removal efficiency of fibers and microgranules removal (over 90%). Microfoils were removed in less than 50%.