HALOACETIC ACIDS (HAAs) FORMATION IN DESALINATION PLANTS PROCESSES DUE TO DISINFECTANTS 1

SUMMARY Chlorination of drinking water yields disinfection by-products (DBPs). Trihalomethanes (THM) Haloacetic acids and Keto acids are some of the common disinfection by-products. Health Organizations and Agencies, viz. WHO, USEPA, SASO, have already regulated the maximum permissible limits of THMs and HAAs at 80 µg/l and 60 µg/l due to their carcinogenic and mutagenic nature. Formation of THMs by chlorine and other disinfectants in different waters is well documented but there is dearth of information regarding the formation potential of HAAs particularly in desalination plants. In this report, an effort has been made to study the formation of different Haloacetic acids and their dependence on total organic carbon (TOC), bromide, chlorine and residence time of biocide in seawater feed and product of desalination plants. Five types of Haloacetic acids viz. Monochloroacetic, Dichloroacetic, trichloroacetic, Monobromoacetic and Dibromoacetic acids have been identified by GCECD method in seawater and product water. Effect of chlorine concentrations, Total organic Carbon (DBP precursors), and Bromide concentration on the formation potential of HAAs in seawater (feed to desalination plants), product water (from MSF), well water used for blending and blended water were studied. Higher concentration of Bromo Haloacetic acids in seawater could be attributed to high bromide content of seawater. The concentration of haloacetic acid determined in drinking water and other streams were found to be very much below the maximum permissible levels of 60 µg/l. The study revealed that use of chlorine as a disinfectant to the product