Closing the loop: Analysis of biotechnological processes for sustainable valorisation of textile waste from the fast fashion industry

The textile industry currently stands as one of the most polluting sectors globally. The proliferation of fast fashion has led to an unprecedented increase in textile production and waste generation, marked by mixed material compositions and significant reduction in the lifespan of each garment. These factors contribute to the creation of complex mixed waste streams, with a majority ending up in landfills. In agreement with international sustainability directives, the textile sector has emerged as a prime candidate for harnessing valuable raw materials from waste. This review specifically targets the transformation of the prevailing linear production model into a more circular one. It focuses on utilizing biotechnological processes to convert textile waste into secondary raw materials to produce platform chemicals and added-value products, able to replace petrochemical-derived materials. The review begins with an extensive analysis of the state-of-the-art and the determination of technically feasible, economically viable, and environmentally sustainable waste valorisation techniques. The focus is on the pre-treatment phases of hydrolysis and fermentation of textile waste to produce industrially promising building blocks. Cotton and cotton-polyester blends, the two most common waste materials in fast fashion, were selected as the primary research materials. Significant variables affecting the efficiency of pre-treatment and hydrolysis methods are identified, highlighting the importance of pre-treatment and the potential use of enzymes for textile hydrolysis. Following the selected studies, the review defines the environmental and economic interests of the projects. These assessments provide essential insights into the sustainability and financial feasibility of the proposed waste valorisation methods.