Enhancement of the requirements to monitoring the safety of drinking water during chlorination

Summary

Oxidative methods involving the use of chlorine and sodium hypochlorite are most widely used for water disinfection. At the same time the regulatory requirements included into the sanitary and epidemiological legislation do not fully reflect the requirements to monitoring their use. A comparative analysis of scientific, technical and methodological literature, as well as of the statutory documents regulating the parameters of the effectiveness and safety of drinking water disinfection with chlorine showed that in the process of developing the first SanPiN 2.1.4.559-96 an exact definition was neglected. It consisted in the fact that the quantitative indicators of these parameters shall not stipulate mandatory simultaneous presence of free and combined residual chlorine in water. The data on the in-process control of drinking water at the water treatment plant in the city of Perm showed no need to maintain the concentration of residual free chlorine at 0.3–0.5 mg/l granting residual combined chlorine in the range of 0.8–1.2 mg/l is available. In this regard it is advisable to introduce appropriate updated requirements for monitoring the concentrations of free and combined chlorine in drinking water in SanPiN 2.1.4.1074-01. When water is chlorinated with gaseous chlorine and sodium hypochlorite a large amount of hazardous halogen-containing volatile and semivolatile compounds including carcinogenic are formed. However, water quality control is carried out only for certain volatile substances. A differentiated approach to the selection of indicators for monitoring the concentration of halogen-containing compounds taking into account the characteristics of raw and disinfected drinking water is recommended.

Key words

chlorination , sodium hypochlorite , water disinfection , chlorine-containing compounds , chlorine , requirements to monitoring , residual free and combined chlorine