Identification of critical issues and development of strategies to increase the environmental sustainability of textile districts in Europe

The textile industry is highly water-intensive, consuming 200-400 liters of freshwater per kg of product, making it the EU's 3rd largest water consumer. The Textile BAT Reference document (TXT Bref) highlights the volume of water discharged and its chemical load as key environmental concerns applicable throughout the European Union, including Italy and Spain. This study examines water-related challenges in the textile districts of Prato (Italy) and Catalonia (Spain), aiming to develop strategies for enhanced sustainability through innovative wastewater management, resource recycling, and sludge treatment. TXT BAT conclusions introduced associated emission levels (BAT-AELs) for direct and indirect wastewater discharges. Consequently, textile companies characterized by indirect discharge will be supposed to respect the BAT-AELs of certain contaminants unless the downstream wastewater treatment plant (WWTP) can abate these contaminants. In this study, mass balance calculations of two WWTPs located in Prato were conducted to verify that the removal of specific pollutants primarily originating from textile processes resulted from an effective treatment process and not merely a dilution effect with domestic wastewater. The findings confirmed the effective removal of critical compounds like COD, BiAS, sulfides, phenols, and hydrocarbons. Contaminants like Zn, Cu, Ba, Crtot, and Sb showed >50% removal efficiency, though results varied with sampling procedures. TXT BAT conclusions promote reuse and recycling to reduce freshwater use and wastewater generation. Prato, home to Europe’s largest wastewater recycling plant, faces challenges with high hardness in reclaimed water from Baciacavallo WWTP. It was demonstrated that an ultrafiltration-nanofiltration (UF-NF) pilot plant can reduce water hardness by more than 98%, regardless of the operating conditions. Furthermore, a simplified steady-state model of the chloride cycle revealed that replacing ion-exchange resin technology, used in Prato for water softening, with a UF-NF system leads to a substantial reduction in chloride concentration, enabling the reuse of reclaimed wastewater for other purposes such as irrigation. This research demonstrated that NF can treat dyeing wastewater and reuse the permeate for the dyeing process, thereby avoiding freshwater consumption and recovering salts. To this end, a laboratory NF pilot plant was employed to treat and reuse wastewater from the dyeing of cotton with reactive dyes. Permeate reuse had no impact on the final product's color reproducibility and allowed saving up to 24% of NaCl and 32% of Na2CO3. Moreover, electrochemical oxidation was applied to treat the NF concentrate, resulting in a color degradation level exceeding 95%. This outcome suggests the potential for the reuse of the concentrate, accompanied by the recovery of additional resources. Textile sludge (TXS) disposal, mainly via landfilling or incineration, is an environmental challenge. Therefore, in this work, biochemical methane potential (BMP) tests were conducted on three types of sludge (i.e., municipal, textile, and mixed) to assess anaerobic digestion (AD) as a potential sustainable treatment alternative. The results demonstrated the feasibility and benefits of AD for the valorization of TXS, with co-digestion as a promising approach to maximize biogas production efficiency. Finally, the study addressed microplastic (MP) pollution, proposing a method to quantify and identify MPs in wastewater. Understanding WWTP efficiency in MP removal supports efforts to mitigate emerging environmental concerns. The study outlines strategies to improve the environmental sustainability of textile districts. By adopting technologies like NF and AD, industries could reduce resource use, enhance wastewater treatment, and recover byproducts. It also highlights the need to tackle issues like microplastics with advanced monitoring, promoting sustainable practices in the European textile sector.