Study of trihalomethanes potencial formation in Extremoz-RN pond

ABSTRACT Trihalomethanes formation potential (THMFP) has been used to evaluate the possibility of disinfection byproduct (DBP) formation by chlorination during the water treatment process. Trihalomethanes (THM) are organochlorine compounds and represents the sum of chloroform, dichlorobromomethane, dibromochloromethane, and bromoform, and is the main class of DBP formed from the reaction between free residual chlorine and natural organic matter (NOM) present in the source waters of surface fountains. This research evaluates the THMFP on the source water from the Extremoz Pond (Natal-RN, Brazil), which is treated by direct filtration followed by chlorine disinfection. Results indicated the presence on source water of hydrophilic natural organic matter with the predominance of fulvic acids. The mean concentration of TTHM7 (4.22 mg.L-1) showed that the source water has a strong potential for halogenated organic compounds formation. Chloroform represented about 80% of the total THM concentration in the assays performed. Significant and strong correlations were observed between hardness (R = 0.90 and p = 0.005) and apparent color (R = -0.93 and p = 0.002) attesting that Ca2+ and Mg2+ ions can promote the formation of THM, as well as the apparent color.