DBP formation during chloramination

Batch experiments were conducted on three diverse water sources to study th e formation of dissolved organic halogen (DOX), trihalomethanes (THMs), hal oacetic acids (HAAs), and cyanogen halides (CNX) during chloramination. The authors used preformed chloramines to examine the effect of pH, mass ratio of chlorine to ammonia-nitrogen (Cl-2 to N), and bromide concentration on disinfection by-product (DBP) formation. Formation of specific DBPs as well as the group parameter DOX was greatest at low pH and high Cl-2-to-N ratio s and followed the general trend of decreasing with increasing pH and decre asing Cl-2-to-N ratio. Bromide addition increased the concentration of brom ine-substituted DBPs and DOX. These experiments demonstrated that because o f dihaloacetic acid formation, HAA formation is more problematic during chl oramination than THM. formation. Because the specific DBPs measured in this research (THMs, six HAAs, and CNX) accounted for no more than 35 percent o f the DOX concentration, utilities may want to consider both specific DBPs and DOX in selecting appropriate chloramination conditions.