Substantiation of halogenated by-products generation in the chlorination process of natural drinking water resources by analytical investigation

Abstract

Chlorine, the most commonly used disinfectant for the drinking water treatment industry, has also an application for several other water treatment objectives, such as oxidation of iron, manganese, hydrogen sulfide, and ammonia, prevention of algal growth in sedimentation basins, maintenance of biological stability of drinking water by prevention of bacteria regrowth in the distribution system. Natural organic matter (NOM) like humic substances present in water resources reacts with aqueous free chlorine or free bromine, halogenated by-products being formed. Only a small percentage of halogenated by-products has been regulated in drinking water, most of them with adverse effects on human health: trihalomethanes (THMs) with MAC of 80/100 µg/L (US/EU regulations) and haloacetic acids (HAAs) with MAC of 60 µg/L (only US regulations). The main indicator of the amount of halogenated by-product that could be expected to form in the distribution system if chlorine is applied in water treatment (oxidation/disinfection steps) is considered to be "disinfection by-products potential formation (DBPF)”. For evaluation/quantification of some halogenated by-products (THMs and HAAs) generated by the reactions between chlorine/bromine and NOM, performant analytical investigation methods are needed.