The study of enhanced coagulation process efficacy and direct filtration's effectiveness on elimination of natural organic materials from surface waters

One of the main problems of surface water resources is high concentrations of natural organic matter (NOMs). NOMs may be made as extra products of disinfection which could be toxic or carcinogenic for humans. The aim of this study was to evaluate the effectiveness of enhanced coagulation and direct filtration process on elimination of NOMs from surface waters. In this quasi-experimental research, a pilot study was designed for enhanced coagulation and direct filtration with a capacity of 144 liters per hour. Choghakhour wetland, located in 65 km far from Shahrekord City, was selected as a sampling location. To measure NOMs, UV absorption at 254 nm was used through a spectrophotometer. The effect of PH, FeCl3 dosage and flow rate was studied to evaluate the elimination of NOM. The results showed that in the optimum conditions, the elimination of NOMs was about 94 percent and the amount of residual contaminants was about 2 mg/l. The optimum condition to remove the NOMS, was observed in PH 6.2, ferric chloride dose 60 mg/l and flow rate of 95 l/h. According to analyses of under study factors, coagulation concentration showed the most efficacies on the removal efficiency of NOMs, PH and flow rate, respectively. It can be concluded that enhanced coagulation and direct filtration through ferric chloride can improve the NOM removal efficacy in the water treatment plants.