Discharge of wastewater contained detergent into water body causes entering phosphate compound into water and Eutrophication. Today, replacement of common detergent is not economically. One of the water and wastewater treatment methods is chemical coagulation. This method produce huge amount of sludge and has high sludge disposal expenses as a result of using chemical materials. Electro coagulation is a suitable method for replacement of common chemical coagulation. In this technology, coagulants release in solution by solving electrode instead of utilizing metallic salt or polymer. In this study ability of electro coagulation and complementary flocculation by using iron as electrode in treatment of wastewater contained detergent was evaluated.COD removal was evaluating factor of removal efficiency. In order to optimize the removal efficiency, four factors including pH, initial detergent concentration, electrolysis time and electrical current were investigated and experiments were carried out in batch reactors. Full factorial method was used for studding any of these factors and optimum condition was determined. Results showed that in optimum conditions electro coagulation and complementary flocculation with iron is capable of reducing COD concentration from 217 mg/L to 81.3 mg/L. furthermore ANOVA analyze showed that all of the experimental factors were statistically significant. ANOVA results revealed that the contribution of error term in the total results for all of the samples is less than 16%. Interaction analysis were carried out to investigate the relative importance of different interactions between involved factors in this sample and it was concluded that the most important interaction in this sample happens between pH and initial detergent concentration. Considering the behavior of the coagulants results it was concluded that charge neutralization and bridging are the most important mechanisms in detergent COD removal using waste iron electrode. Also the experiments showed that final pH samples after of electro coagulation and complementary flocculation increased and in optimum condition, it was equal 8.04. Moreover examination revealed that electro coagulation and complementary flocculation in compare of chemical coagulation with ferric chloride and ferric soleplate was used less coagulation and produced less sludge volume and reached higher COD removal. Overall, this study showed that electro coagulation and complementary flocculation is capable of decreasing detergent COD and can be used as a cheap, easy application and low producing sludge alternative in wastewater treatment. Key Words: Detergent , electro coagulation, complementary flocculation, Iron electrode, Full factorial
