Development of New Disinfection Indicator in Chlorine Contact Tanks

Abstract

Abstract Although alternative methods for evaluating disinfection performance have been developed recently, the conventional CT value has been widely used due to its simplicity. This research proposes a simple, nondimensional variable chlorine disinfection index (CDI), which is derived from a chlorine decay constant, an inactivation rate constant, the initial dosage of chlorine, and the deadzone volume percentage, and investigates its possibility as a new disinfection indicator. To assess disinfection performance using CDI, 75 cases were created from each factor's value, based on previous research, and simulated using the computational fluid dynamics model. Results showed that CDI is linearly correlated with log inactivation of microorganisms, but that the relation varies with the value of the chlorine decay constant. Although the CT value is also correlated with log inactivation by linear regression, the relationship of the CT value to log inactivation is different with the inactivation rate being consta...