Sensitivity of Esch. Coli and Poliovirus to Different Forms of Combined Chlorine

This article discusses the term “combined available chlorine,” which refers to forms of active residuals of chlorine other than free chlorine. Combined chlorine is thus an empiric definition, which may cover any form of chloramine that is able to react as an oxidant in the chosen analytic system. A better understanding of chlorination resulted when it was recognized that the efficiency of free chlorine by far exceeded that of combined chlorine. In early works, the effect of chlorination was studied by using different compounds containing – or under the conditions applied, resulting in formation of – combined chlorine. The results are difficult to evaluate because they were obtained before a distinction was made between free and combined chlorine. Because it appeared questionable that unlike forms of combined chlorine actually possessed the same disinfecting capacity, the experiments reported in this article were carried out to study the inactivation of Escherichia coli and of poliovirus using different forms of combined chlorine.