Effect of water treatment process on organochlorine pesticide residue levels in Ahvaz water treatment plant No.2 .

One of the main hazards of human life and health is the presence of pesticides in the aquatic system is. The Karun River is the surface water source in the preparation of drinking water for the city of Ahvaz city at the Ahvaz Water Treatment Plant. (AWTP)No.2. This study was done in order to investigate the statue of qualification and the quantification of the contamination of waters entering into (AWTP)No.2 by selected organochlorine pesticides [(α, β, γ, δ )HCH, heptachlor, alderin, dielderin, (op’ , pp’ ) DDT, (α, β) endosulfan and metoxychlor], plus the water treatment effects on these pesticide residues removal. For this purpose, one composite sample from each of the water treatment process steps was taken monthly which was comprised of 20 grab samples in 2008. Water samples were acidified to pH < 2, extracted three times with n-hexane, and concentrated using a rotary vacuum evaporator for Florisil column chromatography cleanup and fractioned by elution with three different solvent mixtures of petroleum and diethyl ether. Finally, the elutes were concentrated to dryness using rotary vacuum evaporator and then the residues were dissolved in hexane and analyzed by GC- μECD. All 12 investigated organochlorine pesticides were detected. Results of this study indicated that concentration of investigated pesticides decreased (according to the kind of pesticide) by 20% to 80% and the mean of total concentration was reduced by 49% during water treatment process steps. There was a significant positive correlation (r=97.75%) between variation in the concentration of poisons and the total organic matter (KMnO4 value)