Reuse of Salt-Containing Dyeing Effluents by Means of an Electrochemical and Ultraviolet Coupled System

Abstract

The textile dyeing produces a large volume of wastewater with high salinity and deep colouration. Residual dyes are generally not removed in conventional wastewater treatments, and therefore, specific treatments are required to remove colour. Sometimes, textile mills are not able to accomplish water discharge regulations as salts cannot be removed in the common wastewater treatments. To face both problems, salinity and colour of effluents, a new system has been designed based on a coupled electrochemical and UV process (EC-UV). It is a fast and simple treatment that enables the effluents colour removal. In addition, the wastewater salinity can also be reduced through the reuse of the treated effluents in new productive processes. The treatment is particularly efficient in the reactive dyeing process, although it can also be used for effluents of direct dyes. The implementation of this new system in the textile industry achieves significant benefits. The reuse of effluents containing high amount of salts implies lower consumption of water and salt in the dyeing process, and the removal of colour improves the yield of wastewater treatment plants with less consumption of chemicals. Finally, the reduction of wastewater salinity is also an additional economic and environmental benefit of the treatment, which results in lower wastewater taxes and improvement of the aquatic ecosystems.