Still waters run deep

We have seen the dangers of several pollutants in the history of mankind that have persisted in the environment and in the news. Microplastics have stolen the headlines recently because of the way they persist and damage marine life. The main polluting sources of microplastics are well-known and widely understood whether it be tyres, cosmetics, disintegrating plastic products or textiles. It feels somehow easier to aggregate and categorise all these sources into large visible boxes with no regard to the way these products are made and maintained throughout their life.

To some extent, these large boxes work perfectly well for the main sources of microplastics such as plastic products thrown into the marine environment, shedding of polymers from tyres, microbeads in cosmetics and so on. Textiles, however, are much more complex products than any other category because of the way these products exist in our lives. We have the responsibility then to carefully distinguish some of the data that are published between fast fashion products and highly sustainable industrial rental products that are manufactured and maintained very differently.

An average consumer may not see any difference between a cotton shirt they wear to a cotton towel they used when they last stayed in a hotel. Those who use workwear or personal protective equipment in their workplaces should ideally understand the difference in the way these articles are designed and maintained. Clearly, different textile products are miles apart from each other - from the way they are made - to the way they are cared for - to the way they are managed at the end of life. Industrial workwear has a very different purpose, use and maintenance over its life compared to a fast fashion product. However, there is a growing tendency to cluster the data relating to industrial laundry rental products with that of fast fashion and retail textile products. This is an erroneous approach and overlooks where the real solutions need to be targeted. Furthermore, it makes us ignore from whence some solutions may be adopted.

Good practice

There are plenty of good practices in the industrial laundry processes, equipment and products that in fact reduce the abrasion of polymeric elements of a textile product. Industrial processes are designed and optimised to the last micro-inch for efficiency and effectiveness. For example, studies have highlighted that industrial tumble dryers and liquid detergents used in industrial processes reduce the overall shed of textile fibres whether they are polymeric or cellulosic (biodegradable and not constituted as microplastics). The study by De Falco et al. (2018) shows that powder detergents seem to stimulate comparatively more fibre release. The findings from the Swedish MinShed project (presentation by Hanning and Söderberg, December 2019) indicate that tumble drying decreases the fibre release into the water stream in the subsequent wash due to the removal of lint during tumble drying.

It is well known that a large proportion of fibre release happens at the first and second washes. The study by de Falco et al. (2019) shows that the first wash contributes to the highest release of fibres and this is confirmed by other studies (e.g. Napper & N C Thomson (2016). After five washes these numbers are reduced to around the halves, and after 10 washes they are down to around one-tenth of the first wash. There is also consensus about the order of magnitude of the release of fibres between several researchers. For polyester, the mean value is 0.27 g/kg – varying between 0.13 and 0.39 g/kg – or around 0.03% of the textile weight is lost during the first wash. The summary then is that the longer use of textiles products is the best way to combat the release of microplastics from clothes. This is another reason to clearly distinguish the data for different textiles sources. Home washing and fast fashion would contribute a large portion of microplastics compared to an industrial rental process where the processes are designed to extend the life of their products to the maximum.

There is also a big difference when it comes to the types of material in use. More than 70% of the UK’s industrial textiles are either 100% cotton or cotton-rich products. The industrial products used in the hospitality and healthcare sectors would constitute less than a few percentages of all the UK’s microplastic pollution from textiles. This is due to large-scale efficiencies and long life cycles achieved by industrial rental services.

More cotton

From other studies and tests, it is also clear that cotton releases far more fibres per amount of cotton in the fabric than polyester. When calculating the release per gram of material on average, the cotton fibres in the fabric released around 1800 fibres per gram of the cotton, while polyester on average released only around 340 fibres per gram – for the blends tested. Please bear in mind the difference between the terms ‘fibres’ and ‘microplastics’ when making your judgment on these numbers. It is significant because industrial laundry filters are capable of capturing a wide scale of fibre sizes from ‘larger’ types to substantial micro sizes. UK’s Textile Services Association supports its European counterpart’s position on this issue. Generally, textiles applied in textile service are high quality – high twist with tight weaving/knitting. These products consequently release a relatively limited amount of microplastics.

Even with the best products and process mix, certain polyester or polyester/cotton blended fabrics from which healthcare, hospitality and industrial items are manufactured and which are industrially laundered, may to some degree shed their fibres. However, the data on this cannot be mixed together with fashion/retail products. The minute plastic and more evident cotton lint fibres are consequently present in the industrial effluent discharged to sewer from laundry sites.

Many elements

The effluent constitutes many other elements, including detergents, mineral and proteinaceous oils and greases and settleable solids, the levels of which are routinely measured and charged for by the water companies. At certain larger laundry sites, the practice of effluent filtration in order to recycle and reuse the process water as well as to recover some of its useful heat is common. It is still the case that the effluent in a more concentrated form (reduced volume) is discharged to the sewer. The water companies apply the Mogden formula in order to calculate the charge. The industrial laundry effluent may be effectively filtered or perhaps the microplastic fibres may be broken down by physio-chemical oxidation; both options must be technically developed and proven as well as cost evaluated.

Although there are several emerging technologies looking at disintegrating microplastics using electrolysis, enzymatic reactions etc., the energy consumption to implement these technologies can create newer challenges. If this can be managed at scale by the water treatment companies as we currently do with other effluents in wastewater, that would achieve great efficiencies while addressing the problem. There are huge technical challenges to overcome to make this happen at scale.

Our industry is also engaged in the development of British, European and international standards that measure the shed of microplastics from textiles. The ETSA standards group chaired by the TSA is battling similar issues in scope and content of the currently developing standard BS EN ISO 4484 (draft). This three-part test method standard is intended to measure and evaluate the release of microplastics from ‘textiles’.

The danger is the tendency to categorise all textiles into that one large box as we saw earlier. The standard drafts in their current form are not geared to be used for commercial laundry products at all. We have a lot of work to do in the coming months to ensure that standards developers and policymakers understand these differences and the importance of the role our industry has to play for a sustainable and responsible future.

One thing is clear; this problem cannot be addressed by working in our own silos – we need much more constructive collaboration, sensible standards, the right information and good research to combat the issue. The entire value chain - from design/manufacturing all the way to water treatment - needs to work together if we are aiming for lasting changes.