Towards a Cleaner Textile Industry: Using ASEC to Decrease the Water Footprint to Zero Liquid Discharge

Abstract

Textile manufacturing is the second most polluting industry. It involves a series of processes that require large amounts of water and generates highly polluting wastewater. Four liquid wastes collected at different steps from two different textile factories (synthetic and natural fibers) were treated using a new disruptive technology (Adiabatic Sonic Evaporation and Crystallization—ASEC). After the treatment of the contaminated fluids, the byproducts obtained (freshwater and crystallized solids <1% humidity) were characterized to determine depuration efficiency and their potential commercial reuse. The physicochemical parameters were analyzed in the liquid and solid phases. The results evidence a completely efficient separation of the contaminants and solutes from the liquids analyzed, resulting in 100% pure water with the characteristics of distilled water (an electrical conductivity below 20 µS/cm) suitable for other industrial processes or water reuses, including human consumption. This implies an estimated annual reduction in the water consumption of these factories of between 16 and 103 Olympic pools. It would also avoid the disposal of 181 and 966 ton/y dried residue by the current synthetic and natural fiber textile processing factories, respectively. More than 75% of the resulting solid residue was S from the synthetic fiber industry, and light elements from the natural fiber residues. The installation of ASEC technology in different phases or at the end of industrial textile processing lines could change the paradigm of water consumption to a minimum, thus reducing consumption and resulting in the complete recycling of water. Using renewable energy and residual heat transforms the system into a zero-pollution technology; it makes it possible to attain almost 0% CO2 emissions, fulfilling the European Green Deal objectives such as a circular economy, the decarbonization of the textile industry, the protection of the biodiversity of river basins, and zero pollution.