Effect of Calcium Bicarbonate on Disinfection by Halogens

The inorganic entities in water comprise a significant portion of chemicals in water and their effects upon the disinfection process should be fully evaluated. This investigation was undertaken to determine possible effects of various inorganic chemical additives in water on the efficacy of disinfection by halogens. The chemical used in this experimentation was calcium bicarbonate. Halogen concentrations used were on an equal equivalent weight basis. The test microorganism was Escherichia coli. The exposure substrate was cold sterile distilled water to which appropriate quantities of calcium bicarbonate were added. All bacterial exposures to disinfectant were performed at pH values 5.0 and 7.0 and a temperature of 2-3°C. Bacterial death kinetics are presented in comparisons of varying additive conditions for each halogen and also for constant additive conditions for all halogens used. A hampering effect of calcium on the disinfection efficacy of chlorine, bromine and iodine was found at the conditions of the experimentation.