Quantification and characterization of microplastics released by mechanized laundry washing

Abstract

Concern about the contribution of laundry washing in natural environments to microplastic (MP) pollution in water bodies motivated this study, which quantified and characterized MPs released by domestic washing in a washing machine with a capacity for 14 kg of clothes. Three effluent samples (A1, A2, and A3) were collected on different days under typical usage conditions ("Normal" program, "Extra High" water level, liquid detergent, and fabric softener). 50 mL aliquots of each sample were oxidized with H₂O₂ at 60 °C, subjected to density separation with NaCl, and filtered. The particles were counted using a stereomicroscope (20×) and identified by FTIR-s. A total of 143, 49, and 26 MPs were found in A1, A2, and A3, respectively, equivalent to 520–2860 MPs L⁻¹ and 1.01 × 10⁵–5.58 × 10⁵ particles per wash, considering a volume of 195 L. Black was the most frequent color in the sample with the highest synthetic fabric content, and FTIR spectra indicated polyester/PET as the main polymer. Although lower than the values found in industrial laundries, these numbers show that each household wash can release hundreds of thousands of MPs into the sewage system, highlighting the need for: washing machine filters to retain MPs; greater MP removal efficiency in sewage treatment plants; replacement of garments made from synthetic materials with natural materials; and tax incentives for more sustainable textile production.