THM AND TOX FORMATION: ROUTES, RATES, AND PRECURSORS.

Oxidation and substitution are important mechanisms in the interaction between disinfectants and naturally occurring organics in water. Oxidation processes are responsible for the removal of organic compounds and precursors of trihalomethanes (THMs) and total organic halogen (TOX). Substitution reactions are the source of chlorine incorporation into the organic matter. Disinfectants differ in their abilities to carry out oxidation and substitution reactions, but studies show that chloramines also add chlorine to organic materials by substitution. Before a decision is made to change disinfectants, operating parameters and chemical functions must be taken into account to achieve the best quality drinking water.