A prototype for on-site generation of chlorinated disinfectant for use in rural aqueducts

Abstract

Sodium hypochlorite has significant potential as a sanitation solution in hard-to-reach areas. Few studies have investigated the optimal electrolysis parameters for its production with volumes greater than 10 L. This study evaluated sodium hypochlorite production through electrolysis in a 22-L prototype and identified the optimal operating parameters. Tests were performed using graphite electrodes with areas of 68.4 cm2 at the laboratory scale and 1 865.0 cm2 at the prototype scale. A design for experiments with different operating times, chloride concentrations, and electric current intensities was developed. The optimal operating time, sodium chloride concentration, and current intensity at the laboratory scale were 120 min, 150 g of chloride per liter, and 3 A, respectively, leading to the production of 5.02 g/L of the disinfectant with an energy efficiency of 12.21 mg of Cl2 per kilojoule. At the prototype scale, the maximum sodium hypochlorite concentration of 3.99 g of chloride per liter was achieved with an operating time of 120 min, a sodium chloride concentration of 100 g of chloride per liter, and a current intensity of 70 A, reaching an energy efficiency of 42.56 mg of Cl2 per kilojoule. In addition, this study evaluated the influences of the chloride concentration, current intensity, and operating time on the production of sodium hypochlorite at the two scales, and formulated the equations showing the trends of sodium hypochlorite production and energy efficiency in the electrochemical systems. The 22-L prototype model for production of this oxidizing substance is promising for disinfection of large volumes of water in areas that are difficult to access.