Fate and transport of chlorine dioxide: Modeling chlorine dioxide in water distribution systems.

This study aims to conduct a comprehensive analysis of switching disinfectants from sodium hypochlorite bleach to chlorine dioxide (ClO) in the water distribution system of Geyikbayiri, Antalya. For this purpose, bulk decay rates of ClO at various water temperatures were determined in laboratory studies. The study revealed ClO bulk decay rates of 0.12639 day, 0.17848 day, and 0.19621 day at temperatures 15°C, 20°C, and 30°C, respectively. The EPANET, a widely employed computer program for simulating the extended-period behavior of hydraulic and water quality in pressurized pipes, was utilized for the analysis of the fate and transport of ClO. A hydraulic model was first developed, calibrated, and verified using distinct data sets. The Hazen-Williams friction coefficient of the PSA was determined to be 120 by the trial-and-error method with a mean absolute error (MAE) of 0.408 m. A ClO model was then integrated with the calibrated and verified hydraulic model, revealing a wall decay rate of 0.01 m/day and an average MAE of 0.034 mg/l. After calibration and verification of the ClO model, several management scenarios were developed, and ClO dosing rates were determined. The study showed that ClO dosing rates of 0.40 mg/l and 0.45 mg/l should be applied to keep ClO concentrations within certain limits. PRACTITIONER POINTS: Disinfectants must maintain a sufficient residual in water distribution systems. Chlorine dioxide requires less contact time and is not affected by pH fluctuations. Modeling serves as a decision-making tool for the management of disinfectants. Bulk and wall decay rates of chlorine dioxide are crucial for management strategies. Chlorine dioxide is a good alternative as a disinfectant in such systems.