Separati̇on of oil-water emulsions by electrocoagulation processes

Oils, which are a fairly common pollutant in water today, are usually found in emulsion form in petrochemical plants, mining operations, food industries and in water formed as a result of many industrial processes. In addition, oil spills/spills that occur continuously during oil transportation and oil production over the sea cause oil containing a large amount of oil-based pollutants to mix with water resources and form oily wastewater. Since frequent occurrence of oil spills-accidents and discharge of emulsified oil-water mixtures directly to receiving environments will have harmful effects on the environment and living life, efficient treatment of such wastewater is of great importance. In this thesis study, it is aimed to separate oil-water emulsions by electrocoagulation (EC) which is evaluated as an effective and promising method for sustainable water management and electro-persulfate method (EPS) called advanced electrocoagulation process. A model oil-water emulsion was prepared for experimental studies. As a firstly in the study, oil-water emulsions with three different electrode configurations were treated with EC and the most economical electrode pair was determined. Afterwards, operating conditions of EC and EPS were modeled and optimized for the treatment of oil-water emulsions process by response surface method (RSM) and Box-Behnken design (BBD). Operating parameters with BBD (pH, current density, and electrolysis time for EC; pH, current density, persulfate (PS)/COD and electrolysis time for EPS), effects on system response (COD removal) and their interactions with each other have been revealed. At neutral pH, the optimal operating conditions determined with the help of the model for maximum COD removal are 27 mA/cm2, 37 min for EC and 27 mA/cm2, 25 min and PS/COD=0.5 for EPS. Whereas The COD removal efficiency estimated as 100% and 88.18% by BBD under optimum conditions, tests results in the same conditions were 97.15% and and 87.94% for EC and EPS respectively, and the total cost was 2,061 €/m3 and 1.19 €/m3 for EC and EPS respectively. As a result of the study, EC achieved higher wastewater treatment performance than the EPS process. However, from an economic point of view, the EPS process has enabled the treatment of more efficient oil-water emulsions. Keywords: Electrocoagulation, Electro-persülfate, Optimization, Sonication, Oil-water emulsion