Microplastic fibre releases from industrial wastewater effluent: A textile wet-processing mill in China

Abstract: Microplastic fibres (MPFs) released from textiles are routinely found throughout the environment indicating human impacts on natural systems. The most common release pathway to the environment investigated are domestic textile laundering, transport through and retention in municipal wastewater treatment plants and subsequent application of processed sludge onto agricultural fields as soil amendment. A less-studied but potentially equally relevant source is releases further upstream in the textile production chain such as industrial wastewater effluents from textile processing mills. In this context, industrial wastewater from a typical textile wet-processing mill in China was sampled to estimate MPF release. Effluent was sampled and MPF fibre number and length were quantified by stereomicroscope. An average of 361.6 ± 24.5 MPFs L-1 was identified in the mill effluent. MPF length was highly variable, yet 92 % of all fibres were shorter than 1000 µm. Additionally, the sampling strategy was used to identify the optimal volume necessary to adequately subsample the effluent. We found that total fibre counts were linearly correlated with sample volumes between 1 and 10 L, but a sampling volume of 5 L is suggested for good reproducibility, low standard deviation and ease of working volume. The significant abundance of MPFs in the industrial wastewater effluent emphasises that not only should attention be placed on domestic releases, but the production stage of textiles can also be responsible for MPF pollution. The ability to target and treat industrial effluents may significantly reduce a potentially major point source.