Integration of electrochemical technologies to produce chlorine dioxide: A solution for disinfection processes

This work introduces a novel, scalable strategy for on-demand ClO 2 generation through the continuous electrochemical production of HClO 3 and H 2 O 2 as key precursors. The integrated process comprises four stages: electrochemical oxidation of NaCl to ClO 3 - in an undivided cell under ambient conditions without catalytic additives, purification of the resulting solution via air stripping, acidification of ClO 3 - to high-purity HClO 3 using bipolar membrane electrodialysis (BMED), and optimized electro-synthesis of H 2 O 2 . Results demonstrate that the integration of electrochemical oxidation and BMED enables efficient and safe conversion of chloride to chlorate and subsequent acidification. Small doses of electro-generated H 2 O 2 enable selective in situ reduction of HClO 3 to ClO 2 , achieving controlled gas-phase transport without Cl 2 formation at flow rates of 0.009-0.049 mg min -1 . Applied to hospital effluents, ClO 2 achieved complete disinfection using Klebsiella pneumoniae as a model pathogen, requiring 1.67 g per m 3 of urine per log unit of bacteria reduction. Enhanced gas-liquid contact via jet aeration accelerates disinfection kinetics and minimizes oxidant consumption, positioning this approach as a safe and cost-effective solution for mitigating antimicrobial resistance in healthcare wastewater streams. Finally, a comparative analysis of ClO 2 against other oxidants demonstrated ClO 2 ’s comparative advantage under the tested conditions in hospital effluent disinfection. • Efficient chloride-to-HClO 3 conversion via electrochemical oxidation and BMED. • Small H 2 O 2 doses enable controlled conversion of HClO 3 into ClO 2 on demand. • High-purity ClO 2 is selectively produced without Cl 2 at mass flow rates of 0.009 - 0.049 mg min -1 . • ClO 2 exhibit high disinfection efficiency in effluents with high organic and biological loads.