LCA study of a new electrochemical and ultraviolet (EC-UV) combined system to decolourise and reuse textile saline effluents: Environmental evaluation and proposal to improve the production process

Abstract

In this work, the environmental performance of the reactive Jet dyeing process and the subsequent wastewater treatment currently carried out in the textile companies is compared with a new system. The developed system combines the application of an electrochemical process with ultraviolet irradiation (EC-UV) to remove colour of effluents containing reactive dyes. EC-UV system is also able to prepare the discoloured effluents for its subsequent reuse in a new dyeing process. The developed system can operate in two modes: decolourisation and decolourisation plus reuse. This study compiles life cycle inventory data for both operation modes and compares their environmental impact with the conventional dyeing and wastewater treatment. The results show that the EC-UV system, running in “decolourisation mode” (ED scenario), has a better environmental performance than conventional decolourisation (CD scenario), since the tertiary treatment is eliminated. The environmental assessment for CD and ED scenarios shows that the dyeing process has the largest contribution to all the impact categories, mainly caused by the consumption of Na2CO3 and NaCl. When EC-UV system is running to treat and reuse water and salt (EDR scenario), the reconstitution step process, necessary to reuse effluents, has a great contribution in most of the impact categories. Based on the obtained results, a modification in the dyeing process has also been evaluated. The proposed modification substitutes the use of Na2CO3 by NaOH in the dyeing process, causing a great environmental improvement in all the impact categories for the EDR scenario, being this scenario the one with better environmental performance.