Super-stable mineralization coupled with electrolysis towards the treatment of leather wastewater containing high-concentration organic pollutants

With the growth of the tanning industry, the discharge of wastewater containing Cr(III) ions and ultrahigh organic contaminants has become a significant environmental issue, requiring efficient treatment technologies. In this work, a super-stable mineralization coupled electrocatalytic treatment technology was developed to treat leather wastewater in two steps. In the first step, the Cr(III) in the solution was efficiently converted to CaCr-layered double hydroxide (LDH) by the super-stable mineralization technology. In the second step, the remaining organic contaminant with a high chemical oxygen demand (COD) was eliminated using NiFe-LDH electrode via electrocatalytic oxidation process. Using citric acid as a model organic contaminant, this work demonstrated a COD removal rate of 84.6%, meeting the discharge standards and demonstrating applicability to other organic pollutants. This method was further demonstrated to be efficient for the treatment of real leather wastewater, thus offers a novel perspective on the treatment/recycling of heavy metal-containing wastewater with high concentration of organic compounds.