Evaluation of a sustainable dye-exhausted resin regeneration method for cost-effective decolorization and detoxification of textile wastewater

Abstract

Despite the efficiency of the ion exchange (IEX) process in eliminating color and toxicity from textile wastewater, its extensive application is hindered by the challenges associated with recovering dye-exhausted resin using conventional regeneration methods. Thus, hazardous polymer-based decolorants are currently used to meet color standards and produce vast amounts of hazardous sludge. This study focuses on the hydrothermal alkaline regeneration (HTAR) method for regenerating exhausted strong-base anionic ion resin as an alternative to the hazardous decolorization method. It mainly emphasizes its application with trademarked regenerant (Veritas Regenerant®) after the resin was employed for decolorization and detoxification of biologically treated textile wastewater (BTTWW), aiming at sustainable treatment and reuse of such wastewater without producing hazardous sludge. The performance of the regenerated resin was assessed through various parameters, including toxicity (Microtox® test), color, chemical oxygen demand (COD), and total dissolved organic carbon (DOC). On average, the anionic IEX process achieved the removal of 96 % of color, 74 % of DOC, 43 % of COD, and 60 % of toxicity from BTTWW. Complete recovery of the resin was successfully attained using the HTAR method at 40 °C. Notably, the performance of the resin remained consistent over 50 multiple exhaustion/regeneration cycles, indicating the viability of HTAR for regenerating color-exhausted resin for repeated utilization in the treatment and reuse of biological textile wastewater. These results underscore the potential of trademarked regenerant in HTAR to improve the pre-treatment of textile wastewater before membrane wastewater reuse systems while also potentially reducing operational color removal costs in the textile sector, estimated at approximately 0.26–0.50 €/m³, to around 0.08 €/m³.