Polymer Identification of Dominant Microplastics in Wastewater Using FTIR and RSM Imaging

ABSTRACT Microplastics (<5 mm) have emerged as persistent environmental pollutants, and wastewater treatment plants (STPs) are recognized as major pathways for their release into aquatic environments. The present study investigated the abundance, morphology, and polymer composition of microplastics in wastewater using an integrated approach combining RSM‐based imaging and Fourier transform infrared (FTIR) spectroscopy. A total of 45 influent and effluent samples were collected over one year from the Erandwane STP, Pune, India. Microplastics were extracted through filtration, density separation, and chemical digestion, followed by quantitative and qualitative characterization. The results showed an overall removal efficiency of approximately 86%–93%. Fibers were the dominant morphological type (50%–65%), indicating substantial contributions from textile‐related sources. FTIR analysis identified polyester (30%–40%) as the dominant polymer, followed by polyethylene (PE) and polypropylene (PP). The characteristic FTIR absorption peaks showed strong agreement with standard reference spectra, confirming reliable polymer identification. The integrated RSM imaging–FTIR approach enabled effective cross‐validation of particle quantification, morphological characterization, and polymer identification, thereby improving the reliability of wastewater microplastic assessment. Despite the relatively high removal efficiency, residual microplastics persisted in treated effluent, highlighting the limitations of conventional wastewater treatment systems. Overall, the study demonstrates the effectiveness of the integrated analytical approach and emphasizes the need for advanced treatment strategies to reduce microplastic discharge into aquatic environments.