investigation of electro and chemical coagulation processes for marine microalgae separationin this study, different methods of separating of the microalgae from the culture medium as one of the most important and expensive steps in achieving commercial production of biodiesel from microalgae was investigated. electro coagulation-flotation (ecf) was preferred among these methods due to its process simplicity and capability to scale up. the effect

in this study, different methods of separating of the microalgae from the culture medium as one of the most important and expensive steps in achieving commercial production of biodiesel from microalgae was investigated. electro coagulation-flotation (ecf) was preferred among these methods due to its process simplicity and capability to scale up. the effect of three parameters, i.e., initial ph, electric current density and duration was investigated on microalgae separation efficiency and operating costs. it was revealed that duration was the most effective parameter on the both microalgae separation efficiency and the operational costs, wherein high efficiency was resulted in long duration. on the other hand, the high amount of electric current density caused high coagulation, flotation rates, and also consumed high power. although the ph of solution had a little impact on operating cost compared with the duration and current density, the natural condition (ph = 6) is recommended. microalgae separationefficiency was obtained 96.8% in optimal point; wherein current density equals 1.6 ma / cm2 for 17.65 min and no need to ph adjustment. additionally, the performance of chemical coagulation (cc) as an alternative to the ecf in microalgae separation was evaluated. the results demonstrate that the optimal coagulant concentration and ph are respectively equal to 450 mg /l and 8 with the separation efficiency of 86%. comparison of performance of these two methods indicate that ecf is a promising method of microalgae harvesting in large scale  due to its more flexibility and lower cost and also less sensitivity to ph changes.