Reducing the environmental impact of textile industry by reusing residual salts and water: ecuval system

Abstract The textile industry is one of the largest consumers of water in the world and its wastewater constitutes a serious problem when it is discharged without the proper treatment. Different techniques are being applied for treating textile effluents. But, as far as we know, none of them consider the reuse of the clarified effluents. In this work, a recently developed wastewater system named ECUVal is proposed to treat and subsequently reuse the effluents generated by the dyeing process of a textile mill, which usually have high dyes and salt content. With this system, a reduction of water and salt consumption is achieved and simultaneously the volume of discharged effluents is also reduced. The ECUVal system is based on an electrochemical treatment assisted by UV irradiation. The system is able to remove colour completely. Colour removal efficiencies between 64 and 99% were obtained depending on the intensity applied. Moreover, the treated effluents are reconstituted in the system to be reused in new dyeing processes. Thus, 70% of water and up to 72% of salt reuse was achieved. The chromatic coordinates of fabrics dyed with the treated effluent were evaluated with respect to reference ones. Dyeings performed with reused effluents were in general into the acceptance limit of the textile industry (DE CMC(2:1)  ≤ 1). Finally, the environmental impact of the wastewater treatment currently performed in the textile companies was compared with respect to the ECUVal treatment by means of life cycle assessment. It was concluded that the use of the system reduces significantly the environmental impact of the textile industry.