Microfiber Emissions from Textile Manufacturing Industries: A Critical Review.

Microfiber (MF) emissions from all types of textiles, natural, synthetic and semi-synthetic, are not well studied with most papers identifying domestic washing as the major cause of MF leakage; however, this ignores large-scale MF shedding during manufacturing. In the last 5 years, only 10 papers have focused on MF release during textile manufacturing, highlighting gaps in knowledge. A review of available literature demonstrated manufacturing as an important but underappreciated source of MF pollution and a potential opportunity for mitigation. Varying methods of analysis, levels of replication, and different data reporting norms pose difficulty in gaining a holistic overview of the data available. The need for more stringent research into this area is evident to fully map MF emissions throughout the supply chain and to ensure adequate process design and remediation methodologies. On average, wet processing releases two times more MFs (∼1,300 MF g-1 fabric) than dry processing (∼700 MF g-1), whilst dyeing (∼800 MF g-1) releases most MFs. Wet processes also release 2× more MF mass compared to dry processes, and MF length in wet processing is 57% shorter compared to dry processing. Wastewater treatment plant capture efficiency for MFs depends on MF size in the influent, which in turn depends on the type of fibers used in production, the manufacturing processes, and material characteristics. Scalable "better-by-design" interventions offer a significant opportunity to reduce MF emissions in production, including selecting yarns with higher twist and packing density, laser cut fabrics, pre-treatment of textiles using plasma treatment, low temperature dope dyeing and in-situ dyeing methods with reduced abrasion, and pre-washing textiles before sending to the consumer to reduce MF emissions.