Chlorine Requirement of Water

The chlorine requirement of water is the amount of active chlorine equivalent to the mass of the chlorinated substance in water into which it has turned as a result of chlorine requirement reactions.

The value of chlorine absorption of water is one of the most important indicators of the safety of drinking water, the quality of its preparation with chlorine, and the quality of water in open reservoirs that are intended for drinking purposes. The chlorine absorption of water is determined by two reactions - i) the reaction to the dry residue and ii) to the residual chlorine. The rate of interaction of water with the analytical medium of a working solution of a certain composition and concentrations of the reagents used is determined. Solutions are usually prepared anew. A water sample is tested in three series and the third series is used to calculate the chlorine absorption capacity of water. It is advisable to decolorize tap water without chlorine or with a small amount of it by adding saturated solutions of mineral acids to it, and water containing free sediment needs to be pre-washed. The greater the chlorine demand, the greater the safety of the water and the greater the amount of bleach or chlorine gas required for disinfection. According to GOST, during the period of operation of water pipelines and water towers, constant monitoring of the content of active chlorine in the network is established. The determination can be performed using AKP-1 and AKP-2 analyzers, or using KFK-3 photoelectrocolorimeters, noting the blackening of a transparent strip of paper, therefore the required degree of dechlorination of water at the outlet of the station is determined.