Characterization of Microplastics in Wastewater Treatment Plants and Filtration Using a Sand-Char Model

Naziya Begum, Imtiyaz Jahangir Khan

The current study focused on detecting and removing microplastics (MPs) from wastewater using a low-cost filter. Microplastics are very small plastic pieces that pollute water and can harm both animals and people. For this study, water samples were collected from three treatment plants in Srinagar: Hariparbat STP, Laam STP, and Nishat WTP. The presence of microplastics was studied under stereo microscope, FTIR (Fourier Transform Infrared Spectroscopy), and SEM (Scanning Electron Microscopy). Common microplastic shapes found were cross-network microfibres, fibres, films, fragments, and foams. Hariparbat STP had the highest number of microplastics, followed by Laam STP and then Nishat WTP. Biological treatment was most effective in removing microplastics (91.93%), followed by chemical (65.10%) and physical stage (41.05%) in STPs; however, in WTP, maximum removal efficiency was shown by Physical Stage (69.28%) followed by chemical stage (49.62%). As Nishat WTP does not have a biological stage, it showed lower removal. The main microplastic polymers found were PET, PP, PE, PVC, LDPE, HDPE and PAN. Overall removal efficiency was highest in Hariparbat STP (99.7%), followed by Laam STP (97.66%) and Nishat WTP (84.52%). For removal, a low-cost filter was developed using sand, charcoal, and activated charcoal in different combinations. Among all filters tested, the sand-activated charcoal filter showed the highest removal efficiency (99.5%), followed by the sand-charcoal filter (99%) and the plain sand filter (97.16%). The sand-charcoal filter was the most affordable and effective for wider use in low-resource areas.