Chlorine dioxide bulk decay prediction in desalinated drinking water

• We propose a novel empirical mathematical model for chlorine dioxide decay prediction.
• Model covers decay at a wide range of both temperature and ClO2 concentrations.
• Model provides an unprecedented opportunity to properly design disinfection systems.
• Model verifications indicate good agreement between calculated and measured values.

Chlorine dioxide is one of the most promising disinfectants though usually used as a secondary disinfectant. Several studies addressed the decay rate of chlorine while no study so far tackled the chlorine dioxide decay. This work provides a novel mathematical equation for chlorine dioxide decay prediction in desalinated water.The study was performed at five different chlorine dioxide dosages; 1.4, 1.2, 1.0, 0.8 and 0.6 mg/L (to cover the most frequently used dosages within both production facilities “as primary disinfectant” and/or the distribution system “as secondary disinfectant”). Each dosage had been tested at four different temperatures; 20°, 27°, 35° and 45 °C.To confirm the validity of the proposed decay rate model/equation, site verification was performed (real concentration vs. predicted concentration) and then t-test formula was used to indicate the similarity of both test results.As an overall conclusion, the study’s proposed a novel model/equation that shows reasonable levels of robustness. Furthermore, it covers the chlorine dioxide decay at a wide range of temperature profiles as well as a wide range of chlorine dioxide initial concentration dosages.The proposed model provides an unprecedented opportunity to more realistically plan and model distribution systems to achieve disinfection; among other water quality; goals. Network modelling software such as EPANET provides the platform where the proposed chlorine dioxide decay model can be implemented. Moreover, the model can aid in the decision variables (design, placement, number of stations and operation control & operation optimization) for disinfection boosters in water distribution systems.