Effects of Neutral Salts on the Activity of Iodine, Bromine, and Chlorine as Swimming Pool Water Disinfectants

Abstract

Potassium iodide, potassium bromide, and potassium chloride materially slow down the bacteria killing rates of iodine, bromine, and chlorine, respectively, in distilled water. The germicidal activity of elemental iodine in water does not increase as the pH is increased from pH 5.8 (the mean value fovind in unbuffered water containing 2.0 ppni free iodine) to 8.0 as might be expected if the germicidal activity of iodine could be attributed to hypoiodous acid. Chlorine is considerably less effective as a disinfectant for sea water than for fresh water when judged by activity against the gram-positive test organism S. faecalis. While this can be attributed, in part, to interference by the neutral chloride salts present in sea water, the presence of an initial high chlorine demand and difficulties encountered in maintaining available chlorine residuals after this demand has apparently been satisfied make it impossible to conclude that this is the only factor involved.

Effect of Algicidal Quaternaries on the Germicidal Activity of Chlorine on Swimming Pool Water

“…This method has been accepted as official by the AOAC, and is used routinely in our laboratory for regulatory testing. It has also been successfully employed in a number of investigations concerning swimming pool water disinfection (11,12,16,17). The starting concentration of 0.6 ppm of available chlorine was selected as the lowest concentration which could be used to assure a residual of at least 0.4 ppm throughout the test period.…”