Synergistic treatment of chloride and mine-impacted water using ultraviolet/hydrogen peroxide

Abstract

Paper presents the preliminary concept of salinity reduction in mine water by advanced chloride ions oxidation. New methods and technologies of salinity reduction are crucial in the context of mine water management strategies. These strategies are now the area of concern of coal mining entrepreneurs responsible for saline discharges into environment, which should be significantly reduced or eliminated to meet legal requirements. The study presents the effectiveness of standalone ultraviolet/hydrogen peroxide (UV/H₂O₂, no iron catalysts) as a robust, simpler alternative to complex, multi-stage hybrid systems, e.g., ultraviolet/persulphate (UV/PS) or photo-Fenton) in real, high-salinity mine water. Contrary to the assumption that chloride strictly inhibits oxidation, findings indicate that at high salinity, UV/H₂O₂ maintains high organic degradation efficiency (above 90% in complex matrices). While UV/PS can achieve higher removal in some cases (e.g., up to 99% for chlorinated contaminants at 600 mJ∙cm⁻²), UV/H₂O₂ is highlighted as more environmentally sustainable, as persulphate production contributes a larger environmental footprint than H₂O₂. The advanced chloride ion elimination method is a promising solution for mitigating the impact of saline water on water resources generated by coal mining during the transition period. This approach utilises UV/H₂O₂ for direct photolysis and hydroxyl radical () oxidation, with results showing high efficiency (>90% degradation) on recalcitrant organic contaminants even in complex matrices, demonstrating its effectiveness against chloride inhibition.