Firoozeh Zarkesh - R&D unit, Laboratory of Samiran company, Tehran, Iran
Hamzeh Saghafi - R&D unit, Laboratory of Samiran company, Tehran, Iran
Hassan Koshyar - CEO of Samiran Company, Tehran, Iran

In the present study, it is supposed a simple and inexpensive method for removal of hazardous organic compounds and Chemical Oxygen Demand (COD) elimination of pesticides wastewaters. The process of treatment is based on a physico-chemical method to lessen the level of organic materials using bentonitee, activated carbon, followed by fenton oxidation. The first step treatment was studied in various amounts of bentonite from 0.1% to 1% in different times of 30 minutes to 3 hours, the results have shown a decrease in COD level to 58% in 2 hours by using 0.7% bentonitee. Then for the second step, the amounts of 0.1 to 0.5% activate carbon (AC) in 30 minutes to 3 hours was examined, and the outcome showed an enhancement in COD reduction and by using 0.4% activated carbon in 2 hours the remains COD decreased to 27%. The third and final step was applying fenton oxidation to remove the remain organic materials and COD elimination using 0.5 to 2% H2O2 and 0.005% Fe(II) at pH 4, from 15 minutes to 90 minutes. The best result was given when the combination of 1% of H2O2 and 0.005% Fe (II) were used in 1 hour. The improvement of COD reduction was achieved to 96% and just 4% of COD was remained in this stage and it was shown a high ability of this method for hazardous organic wastewaters treatment. Meanwhile, a sample of main wastewater and treated wastewater were analyzed by HPLC and GC to compare with the results of COD elimination in steps 1 to 3, and prove that the most organic materials in wastewater were removed. This Presented physico-chemical method is easily applicable and economic for plants which have the problem of hazardous wastewater such as pesticides factories.

Wastewater(WW), hazardous wastewaters treatment, Chemical Oxygen Demand (COD), physico-chemical method, bentonite, Activated Carbon (AC) fenton oxidation