Background

"TextileMission" is part of the "Plastics in the Environment, Sources, Sinks, Solutions" funding line of the German Federal Ministry of Education and Research (BMBF). The overarching objectives of the funding line are to develop a consistent picture of the microplastic waste problem and, together with actors from politics, business and society, to identify, develop and implement solutions. Key questions include

•     What is the dimension of the problem?
•     How much plastic can be found where?
•     What are the main sources of the problem?
•     What are the most important entry paths and causes?

Various international studies came to the conclusion that textiles based on synthetic fibres are an important source of microplastic emissions into the world's oceans and inland waters. It has been observed that during the production and household washing of synthetic textiles, microplastic particles are released and cannot be completely retained by sewage treatment plants. They enter the environment via waste water, accumulate and pollute oceans and inland waters as non-degradable plastic waste. However, there is still a lack of precise knowledge on the total amount, precise descriptions of the pathways and data on the extent or proportion of different textiles contributing to the overall problem.

This is exactly where TextileMission comes into play. The project partners examine textile related entry sources of microplastics with a special focus on fleece articles used in the sports and outdoor industry. By its multidisciplinary approach, this joint project contributes to all three key words of the funding priority: "Sources, sinks, solutions".

Status quo analysis: Within the framework of TextileMission a survey of the German-wide introduction of textile microplastics through household linen is carried out. The manufacturers of sports and outdoor clothing involved in the project are providing textiles for intensive washing tests at Hochschule Niederrhein - University of Applied Sciences. The filtered microplastic load is quantified and extrapolated. In a further step, the samples will be examined at TU Dresden with regard to their fractionation (proportion of different particle sizes).

Textile technology research: In addition to polyester-based textiles such as running shirts and football jerseys, the focus is on outdoor articles such as fleece jackets and pullovers. Fleece is a voluminous knitted polyester fabric that is roughened and sheared on both sides after the knitting process. This production creates a soft, voluminous fibrous pile on both fabric sides and forms an air envelope with insulating properties  in addition to lightness, flexibility, volume, breathability and a soft feel. A problem now being recognized is the fibre fragment release during the roughening and warping process.

Textile biopolymers, as substituents for textile polyesters, could provide an approach to reducing microplastic problems. Biopolymers are polymers synthesized by organisms in cells, such as polysaccharides or proteins. The natural fibres cotton and wool are based on these biopolymers. In addition, technical biopolymers used in the textile industry are obtained from renewable raw materials such as viscose fibres or polylactic acid fibres. They can be either bio- or non-degradable (e.g. viscose), such as polyethylene fibres obtained from sugar cane. One promising solution in this project is the sustainable fleece fabric "Biopile",  presented by project partner Vaude at the beginning of November 2017 together with Italian fabric producer Pontetorto. The inner, roughened side of the fabric is not polyester-based (as is the case with conventional fleece), but consists of 100% Tencel wood cellulose fibre, also biodegradable in seawater.

Research on wastewater treatment technology: Studies at Swedish, Finnish, Dutch, Irish, Russian, American and German wastewater treatment plants show that between 65 and 99 percent of the microplastic particles are retained in the process. The majority of the studies find a retention rate of > 95 percent. Nevertheless, even with such high retention capacities, the emission of microplastic particles into the environment is still enormous.

In sewage treatment plants there are different mechanical separation stages to remove suspended particles. In particular, floating material and oil separators, sedimentation tanks and flotation tanks have to be mentioned here. The retention capacity for textile microparticles is investigated on a laboratory scale (5 - 10 L) by the project partner TU Dresden. A further approach: One tenth of the large sewage treatment plants has an after-treatment system, for example sand filters, which purify approx. 13 percent of the total amount of waste water generated in Germany. The retention capacity and in particular the retention capacity of textile related microplastics in sand and activated carbon filters is also investigated.