An overview on the characterization of microplastics (MPs) in waste water treatment plants (WWTPs)

The occurrence of microplastics (MPs) in the environment has become an emerging global concern and has been reported to pose consequential risks to organisms, human health and the environment. Due to their small size (ranging from 1 μm to 5 mm in size), eliminating MPs from wastewater poses a significant challenge, which leads to their accumulation in wastewater treatment plants (WWTPs). This review article explores the method of characterizing MPs in WWTPs to understand their environmental impact better. It also discusses various techniques for characterising MPs in WWTPs, drawing on existing scientific literature. The article provides a comprehensive review of the current methodologies used for the characterisation (chemical, morphology, thermal) of MPs in WWTPs. Furthermore, analytical techniques such as scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy are discussed along with their limitations and potential for recognition and differentiation of various kinds of MPs. The article also highlights the need for standardisation of sampling, extraction, and analytical methods to ensure comparability of results from different studies. The review identifies several obstacles in characterising MPs within WWTPs, such as the absence of standardised methods, restricted detection thresholds, and challenges in quantifying MPs within intricate environmental contexts. To overcome these obstacles, the review recommends prioritising research efforts aimed at enhancing current methodologies, emphasising the need to refine techniques for better comprehension and analysis of MPs within WWTPs.