A new circular economy concept: from textile waste towards chemical and textile industries feedstock

The RESYNTEX project aims at designing, developing and demonstrating new high environmental impact industrial symbiosis between the unwearable blends and pure components of textile waste and the chemical and textile industries. The project comprises: - A strategic design of the whole value chain from textile waste collection, until the new marketable feedstock for chemical & textile industrie, by which the symbiosis opportunities are evaluated (by public authorities and the private sector) in terms of their social, technical, economic, environmental and legislative aspects. - The improvement of collection approaches particularly for non-wearable textiles for recycling by changing citizen’s behaviour and creation of tools for higher social involvement and recycling promotion. This will ensure a greater accessibility to textile waste as resource and increase the textile waste rates destined for recycling. With 50% collection rate all over Europe would be a significant improvement in order to provide large quantities of feedstock. - A data aggregation system that will be developed and implemented in order to ensure waste traceability and also provide relevant data for economic and environmental assessment; - The development of new business models adapted for different synergies identified and for new markets. In addition, environmental LCA and LCC for different scenarios and identification of the most promising routes and synergies will support this objective. - Automation of the macro separation and sorting for pure or blended textiles, in order to enhance productivity and competitiveness of the whole recycling process. - A new demonstration process based on a synergistic chemical and biotechnological cascading separation/transformation approach of textile basic components (proteins, cellulose, polyamide and polyester) from textile blends as basic feedstock materials for chemical & textile industries. Liquid and solid waste treatment and valorisation will close the loop.

The results show that the RESYNTEX system without integration represents higher impact than the reference system for all indicators assessed but with similar impacts regarding human health. The RESYNTEX with water and energy integration shows better performance than the reference system for human health, but it is more impacting for the other indicators assessed. The higher impact for the RESYNTEX systems is mainly due to the high impacts of the biochemical and chemical processes that are not existing in the reference system. On the contrary, the end-product synthesis is always more impacting for the reference system than for the RESYNTEX (but for this latter, the end-product synthesis adds to the biochemical and chemical processes leading to final higher impacts). In addition to this, the incineration of the textile wastes provides sometimes environmental credits to the reference system (depending on the type of textile and the indicator considered). It has to be noted that even if a first step of integration has been considered for one of the RESYNTEX scenarios, it only considers water, energy, partly infrastructures and enzymes and sodium hydroxide integration and not all chemical inputs. It means that this assessment still compares completely mature production routes well optimized for the reference case with industrial scale modelling including only partly integrated data. The RESYNTEX integrated scenario has therefore still a good improvement margin before becoming a mature process. The key benefits identified from the LCA results for improving environmental performance are as follows: • A more in-depth assessment of the main factors contributing to the biochemical and chemical processes shows that further improvements in environmental performance can be achieved by using chemicals (either by using less harmful chemicals or in smaller quantities) and further reducing energy use or substituting for less impactful energy (e.g. renewable electricity or using waste heat from other industrial activities). These improvements should not reduce the efficiency of the process, as maintaining current efficiencies or increasing them is another key element for optimizing the RESYNTEX system. As cellulose and denim material are more important in terms of quantity in the textile blend input, improvements should be made primarily for the biochemical and chemical processes for these materials, together with the improvement for PET processing, which corresponds to a smaller proportion of the textile blend but has a large impact on the overall biochemical and chemical processes. • Infrastructure (machinery) has a non-negligible contribution to the biochemical and chemical processes. Therefore, it is important to choose the best possible equipment with long life, low impact material and easy to dismantle machines to ensure a good recycling rate. • Another aspect to consider when optimizing the system is textile sorting and pre-treatment. In fact, this stage represents a very low contribution to the overall impact of the RESYNTEY system. Consequently, any type of pre-treatment that could reduce energy consumption or goods consumption should be considered at the biochemical and chemical process stage. • The synthesis of final products from intermediate products (outputs of biochemical and chemical processes) is quite efficient compared to biochemical and chemical processes, but also compared to reference processes. The optimal way to improve the performance of the final product synthesis is to increase the efficiency of the RESYNTEX biochemical and chemical processes, increasing the amount of final products for the same amount of textile input. Some other elements related to the synthesis of the final product could be integrated into the improvement thinking. Some examples could be: o conducting research on how to increase the proportion of an intermediate product used in the final product (as for phenol formaldehyde resin); o trying to link the production of the final product with the biochemistry and chemical manufacturing plant to extend the integration process to the final product manufacturing unit, thereby improving energy and water use; to try to find the best formulas and work on the eco-design and sustainable procurement of other components of the final product; or o initiating research and trials to find other possible final products.

As part of the Resyntex project, IOS set up a DEMO pilot plant at a dislocated location in Maribor in 2019. The plant allows for going beyond the size of a laboratory environment and optimizing the recycling processes of textile waste (cotton, wool, PET, PA and their mixtures). The processes are being upgraded for recycling other polymer waste, e.g. plastic and paper packaging. While the depolymerization of PET plastic and textile waste is already ready to enter the market, the recycling of cellulose and PA waste is still in the optimization phase. The demo pilot plant is intended for recycling textile and plastic waste. It consists of two high-pressure / high-temperature reactors and a bioreactor for enzymatic degradation, an extruder and associated peripheral equipment, which includes a chemical dosing system, a belt press, a vacuum filter press, etc. Advantages of the DEMO pilot plant: – Non-apparel textiles can become a useful source for new chemical feedstock, – Improving standards for industrial symbiosis and new models in the circular economy.