Factors affecting the release of microfibers and microplastics from laundry activities: type, quantity, and properties

Microfibers (MFs) and microplastics (MPs) released during laundering represent an important source of wastewater contamination. However, their release dynamics across real-world sources remain poorly understood. This study evaluated MFs and MPs released into laundry wastewater from household, coin-operated, and laundromat sources. Field sampling revealed that laundromats generated both MFs and MPs up to 1.6 × 10 4 pieces/L. Across all sources, fibers in the 20-300 µm size range constituted the largest proportion, and FTIR analysis identified cellophane as the predominant polymer type. Under laboratory conditions, increasing the washing speed from 50 to 150 rpm significantly increased MFs release from cotton reaching 5.2 × 10 3 pieces (MFs)/L, and MPs release from polyester reaching 3.1 × 10 3 pieces (MPs)/L. Front-load machines consistently released more fibers than top-load configurations, whereas detergent formulation (powder, liquid, and gel ball) showed no significant effect. Redundancy analysis (RDA) identified washing speed as the dominant factor governing fiber size distribution, explaining 96.77% for MFs and 99.09% for MPs, while locally sourced detergents were consistently associated with elevated fiber release (RDA, 83.96%). These findings indicate that mechanical abrasion plays an important role in the release of MFs and MPs, and provide critical baseline data to inform mitigation strategies and wastewater management guidelines.