Background & Objectives: Trihalomethanes in the form of chloroform, bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform. Are a group of compounds that can form when the chlorine used to disinfect drinking water reacts with naturally occurring organic matter. Potential hazards and carcinogenic characteristics of THMs have already been recognized. Therefore, current study attempted to measure concentration of these compounds in output (drinking water) of Jlalieh water treatment plant.Methods: In this study concentrations of trihalomethanes with chloroform index have been measured in the output of Jalalieh water treatment plant in 2009. Monthly water sampling carried out in morning. Samples were taken to the lab and sodium thiosulfate was used for dechlorination of the water samples. Samples were analyzed in a time span of less than 6 hours using a GC set.Results: The average concentration of chloroform in input crude water of Jalalieh water treatment plant was equal to 7.42 mg/l. The average pH value in input and output of water treatment plant was equal to 7.92, and 7.87, respectively.Conclusions: The average concentration of chlorine in input and output of water treatment plant was equal to 0.73 mg/l, and 0.94 mg/l, respectively. Although concentration of free chlorine was 0.94 mg/l in output treated water, however, the chloroform concentration in output treated water was lower than the permissible value (200 mg/l) recommended by WHO for drinking water. The highest concentration of THMs was found in April.

Chlorination is a common method of water disinfection in the world, especially in developing countries. But this process can cause harmful compounds such as trihalomethanes. In this research, the effects of different levels of chlorination on trout effluent (cold fish), to produce trihalomethane compounds (THMs), were investigated. Four hundred liters of effluent from a rainbow trout farm sampled and transferred to Laboratory and divided into 15 containers with 20-liter capacity as the experimental unites. Then different concentrations of chlorine (sodium hypochlorite) were added to the containers, including five treatments (control), 10, 20, 30 and 40 mg / l, in triplicates and kept on the shaker for ventilation during a-24hr period. The results showed that the amount of trihalomethane has increasing trend while chlorination increase. So that in the 40 mg / l chlorination treatment, the total trihalomethane concentration was significantly higher and reached to 4 ± 82 μ g / l but in the control treatment, it was 15. 2 μ g / l. However, the mean of produced chloride-bromomethane did not show any significant differences among the chlorinate treatments (p> 0. 05). Also, with increasing the chlorination concentration, the dichlorobromethane and chloroform showed significantly an increasing trend among treatments. Different levels of chlorination had not any significantly effect on bromoform formation. The production of trihalomethanes due to the high level of organic matter in trout farm effluents was higher compared to the global health standards, except in the 10 mg / l treatment. Therefore, the maximum concentration of chlorine for trout wastewater treatment (cold-water fish), was 10 mg per liter, and proposed as a standard level.

Toxicology studies have shown several DBPs including THMs to be carcinogenic or causing adverse reproductive or developmental effects in laboratory animals, numerous epidemiological studies have suggested an increased cancer risk to individuals exposed to chlorinated waters. It has been shown that, regardless of the source, trichloromethane (TCM) comprised approximately 20 percent of the TOX. While there is controversy of the THMs as percentage of TOX, in an extensive study, effects of 3 pH values, 3 reaction times and 4 bromide concentrations on the formation of 4 THMs, trichloromethane (TCM), dicholorobromomethane (DCBM), dibromochloromethane (DBCM) and tribromomethane (TBM) as percentage of TOX have been evaluated. Factorial designs were used to statistically evaluate influences of different factors. Honesty Significant Differences test (HSD) and ANOVA tests were used for the statistical analyses. The Excel graphic software was used for plotting the formation curves, and Lotus 1, 2, 3 was used for the calculations. Statistical analyses showed that the parameters Br, pH and reaction time had significant effects on the formation of TOX and individual THMs. The study revealed that although TCM was the principal percentage of the TOX as THMs in the absence of bromide ion, this compound decreased rapidly with the incremental addition of Br. This study also showed that brominated and mixed species would be dominated in the presence of a high Br concentration which contributes to a high percentage of the TOX.

The reaction of disinfectants with natural organic materials (NOM) existing in water lead to the formation of Disinfection By-Products. Potentially hazardous and carcinogenic characteristics of THMs recognized. Thus removal of THMs or THMs precursor is necessary for human health the aim of this study was to research of efficiency of domestic reverse osmosis (RO) in removal of trihalomethanes (THMs) from drinking water. In this study was used pilot scale of RO system with Polyamide membrane as Spiral-Wound, Tape wrapping module. Feed solution was made by using of pure chloroform. The samples containing chloroform were analyzed using a gas chromatograph, which equipped with a flame ionization detector. By increasing the flow, the removal rate of chloroform decrease and with declining removal of EC, the removal of chloroform was declined too. In this research, at worst condition, the efficiency of the pilot scale reverse osmosis reached to 80 % removal of chloroform.

Background and purpose: Natural organic matter in water resources (mainly caused by humic acid) leads to formation of THMs and HAAs. Removal of DBPs precursors from drinking water resources is the most important step to prevent from THMs formation. The aim of this study was to investigate the efficiency of modified nanoclay with EDTA and fresh nanoclay in adsorption of humic acid in aquatic solutions.Materials and methods: Characteristics and chemical structure of fresh and modified nanoclays were determined via scanning electronic microscope (SEM), BET, XRD, and FTIR techniques. HA concentration was determined by spectrophotometric method in 254 nm. Langmuir, Freundlich models and pseudo-first and pseudo second-order kinetics were used for adsorption isotherm and kinetics studies, respectively.Results: The XRD results showed that the distance between the layers increased after modification of nanoclay with EDTA. Also, BET analysis revealed that specific area of nanoclay increased from 13.02 to 28.36 m2/gr after modification. By decrease in pH the efficiency in removal of humic acid increased and in constant initial concentration of HA by increasing adsorbent dosage the adsorption capacity decreased. Adsorption of HA onto modified nanoclay and fresh nanoclay complies with Langmuir (R2=0.989) and Freundlich (R2=0.96), respectively. The pseudo-first order kinetic complies for both adsorptions.Conclusion: This study showed that in acidic condition the modified nanoclay has an appropriate efficiency on HA adsorption.