Reducing microfibres in textile sector wastewater
Watershed moment for microfibres
Microfibres shed by synthetic textiles during washing are currently in the spotlight, especially their impact on aquatic ecosystems. Researchers are investigating this problem and how to prevent fibres from escaping into the environment.
In municipal water treatment plants they are filtered out of the water, but end up in the sludge that is typically spread on farmland, where the microfibres can still leach into waterways. Polyester, rayon, acrylics, and blends containing these fibres can all shed microfibres.
How does it work?
For producers, the first stage is to identify which steps in the process might be responsible for releasing the most microfibres. The typical way to measure how many microfibres you have at various take-off points is to filter a sample from each point through a fine filter (<2 μm) and then examine it under a microscope. Specialist labs can carry out these measurements if the capabilities don’t exist in-house.
Reducing the number of microfibres in textile industry wastewater is carried out by a number of methods:
- Microfibre catcher: Commercial products which attract microfibres and stop them going down the drain. One claims to be able to collect up to 35 % of microfibres per load, in domestic washing machines. Microfibres tend to be slightly positively charged, so the catchers have negatively charged surfaces.
- Filter bags: Textiles are placed in reusable mesh washing bags with holes small enough to prevent microfibres from escaping.
- Filtering wastewater: Ultrafiltration and reverse osmosis are ways to remove microfibres from wastewater. Instead of treating all process wastewater, it might be possible to just target the effluent from steps that release large numbers of microfibres.
The suitability of these methods depends on the temperatures and chemicals used in various textile production processes.
Companies could also tackle microfibre generation at the product design stage, and these changes would last throughout the product’s life. Consideration of the yarn and fabric properties can affect the amount of microfibres shed, for example :
- Shorter fibres are more likely to migrate to the surface of the yarn and be released during washing
- Reduce shedding by increasing the compactness of fibres, having a higher number of twists
- Fabrics with a tighter structure, i.e. a higher number of yarns per unit length, release fewer microfibres
- The thinner the yarn (higher yarn count), the higher the microfibre release
 Doyle, A. 2017. Plastic found in mussels from Arctic to China - enters human food, https://uk.reuters.com/article/us-environment-mussels/plastic-found-in-mussels-from-arctic-to-china-enters-human-food-idUKKBN1EE194
 J. Bayo, et al. 2016. Microplastics and microfibers in the sludge of a municipal wastewater treatment plant, https://www.witpress.com/Secure/ejournals/papers/SDP110517f.pdf
 Åström, L. 2016. Shedding of synthetic microfibers from textiles, https://bioenv.gu.se/digitalAssets/1568/1568686_linn---str--m.pdf
 Coraball website, https://coraball.com/
 Ecotextile news, April/May 2018, P.32, http://life-mermaids.eu/en/