CHLORINE CONSUMPTION MODELING AND TRIHALOMETHANE FORMATION POTENTIAL: KODIAT MDAOUAR DAM (BATNA, ALGERIA)
Humic substances are the most widely distributed organic products of surface water, they are known by their strong reactivity with chlorine, producing trihalomethanes (THM) THM are classified as carcinogenic compounds that are regulated by the world health organization and other government organizations (CEE, US EPA) After a succession of operations: filtration, softening and concentration with reverse osmosis, Hydrophobic and transphilic fractions of natural organic matter (NOM) were isolated from water supplies (Koudiat Medaour dam Batna) using no polar XAD 7HP and XAD 4 resin. Under standard conditions (pH 7.0 0.2, 25deg C) hydrophobic (HPO) and transphilic (TRS) fractions, are chlorinated with an excess of sodium hypochlorite, then chlorine consumption and UV254 variation are followed. The obtained results were modeled by nonlinear regression using XLStat pro 7.5 software. After seven days of chlorination, the trihalomethanes formation potential (THMFP) was analyzed using gas chromatography LLE GC ECD. The results show that the chlorine consumption of HPO and TRS fractions are practically similar and their values are 1.106 and 1.235 mg Cl2/mg C respectively. On the other hand, the formation of THMFP of TRS fraction (59.62 mg THM/mg C) was more important than that of HPO fraction (32.817mg THM/mg C) The chlorine consumption model confirms the first order with two speeds, the fast speed from 0 to 2 hours and the slow speed from 2 to 168 hours. The characterization of functional groups by infrared (FTIR) shows more important carboxylic and phenolic functions in the transphilic fraction than in hydrophobic fraction, this is in correlation with the strong reactivity of the transphilic fraction compared to that of hydrophobic fraction.