Comparison of Microplastic Detection Methods in Wastewater Treatment Plants

Abstract

A plastic can be turned into millions of fragments of microplastic particles by anthropogenic activities and environmental events (such as wind, UV light, and the water wave action). Due to their surface hydrophobicity, absorbance of persistent organic pollutants, potential to transport contaminants and persistent properties, microplastics have the potential to become widely dispersed in the water environment via hydrodynamic processes and water currents. Plastic materials are durable and, rather than decomposing, they break down into small plastic particles over time. These small particles of less than 5 mm are usually defined as microplastics. As a consequence of the large plastic production rates, plastic waste accumulation in the natural environment has rapidly increased worldwide. However, the effects of plastic wastes in different ecosystems are still largely unknown. Water and wastewater treatment plants are important facilities to estimate plastic waste release to or retention amounts in the environment. Sampling, analysis and standardization of measurements in microplastic analysis is still an ongoing issue. Since wastewater has a mixed matrix, very few microplastic measurements have been made so far. Furthermore, the lack of a standard and viable method to identify microplastics has limited the correct assessment of microplastics and may lead to an incorrect estimation. In this study, microplastic sampling techniques, extraction methods and identification methods of microplastics in wastewater were compared. It was concluded that studies were mostly performed with grap-type sampling, wet peroxite oxidation and identification methods with a microscope and Fourier Transform Infrared Spectrophotometer (FTIR). In the FTIR analysis to determine the polymer structure of microplastics, the most common type of polymers were found to be polypropylene (PP) and polyethylene (PE).