Electrochemical Treatment of Colour Index Reactive Orange 84 and Textile Wastewater by Using Stainless Steel and Iron Electrodes Ebubekir Yuksel, Murat Eyvaz, and Ercan Gurbulak Department of Environmental Engineering, Gebze Institute of Technology, Gebze 41400, Turkey; murateyvaz@gmail.com (for correspondence) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ep.10601 In this study, two case studies were carried out: Electro- coagulation (EC) of a reactive textile dye solution and a tex- tile wastewater. Stainless steel (SS) and iron (Fe) electrodes were used as sacrificial electrodes in parallel connection modes. Effects of pH, current density, and operating time on performance of EC were investigated. Optimum parameters obtained from dye experiments were applied to treatment of the textile wastewater. According to the experimental results, SS electrodes were found to be superior compared with Fe electrodes for treatment of both the dye and the textile waste- water. By using SS electrodes, the textile wastewater was elec- trocoagulated successfully with 89.7% of COD, 91.2% of TOC, 90.3% of turbidity, and 94.1% of TSS removal efficien- cies as well as 2.43 kWh/m 3 of energy and 0.05 kg/m 3 of electrode consumptions, 1.061 kg/m 3 of sludge production, and 0.62 $/m 3 of total operating cost. Ó 2011 American Institute of Chemical Engineers Environ Prog, 00: 000–000, 2011 Keywords: electrocoagulation, stainless steel electrodes, iron electrodes, textile wastewaters, reactive orange 84, eco- nomic evaluation INTRODUCTION Wastewater from both fabric and yarn dyeing pose serious environmental problems because of their color and high COD [1, 2]. Therefore, textile industry is one of the most complicated industry among manufacturing industries. Textile wastewaters contain various waste chemical pollutants such as sizing agents, wetting agents, complexing agents, dyes, pigments, softening agents, and many other additives, which are used throughout the processes. As a result, textile plants produce highly toxic wastewaters [3–6]. Treating these waste- waters have become a real challenge in recent years. Differ- ent combinations of treatment methods have been proposed to effectively manage the above wastewater [7, 8]. Selection of treatment methods for these wastewaters will be governed by their character, the policy of the regulatory body covering the waters of receiving scheme, and econom- ics of the treatment. A large range of physico–chemical proc- esses have been proposed for the treatment of textile waste- waters: coagulation [9], adsorption [10], chemical oxidation [11], photolysis [12], photocatalytic degradation [13], sus- pended [14] or supported photocatalysis [15], and electropho- tocatalysis [16]. Except in the two last cases, they require the addition of chemicals. Conventional process generates large amount of sludge and, in some cases the removal efficiencies are not enough to achieve the discharge limits and hence fur- ther treatment is necessary [17]. In recent years, electrochemical treatment methods such as electrooxidation (EOX) and EC have attracted great atten- tion as an eco-friendly and a cost-effective process [18, 19]. These research works have been focused on the efficiency in oxidizing various pollutants on different electrodes, improve- ment of the electrocatalytic activity and electrochemical sta- bility of electrode materials, investigation of factors affecting the process performance, and also exploration of the mecha- nisms and kinetics of pollutant degradation [19]. EC system includes simple equipment and it provides easy and cost-effective operation, brief reactive retention pe- riod, and decreased amount of sludge. Therefore, a lot of researchers have focused on the efficiency of the system on different aqueous solutions in terms of various experimental conditions. Although many researches on treatment of syn- thetic or real wastewaters with EC are available, very few researches have been carried out on the economical applic- ability of EC in details [20–22]. In this study, technical and economic analysis of C. I. Re- active Orange 84 (RO 84) treatment from aqueous solution by EC with SS or Fe electrodes was studied. Dye and TOC removals were considered while treatment efficiency of the process was measured. The effects of such operational pa- rameters as initial pH, current density, and electrolysis period of the aqueous solution, and distance between the sacrificial electrodes were examined. Suitable experimental conditions were determined and optimum parameters found in these tests were applied to EC treatment of a real textile waste- water. Operating costs were calculated per m 3 of dye solu- tion or textile wastewater and per kg pollutant removed. Electrode and energy consumptions and sludge formations were also presented separately. Brief Description of EC On the contrary of chemical coagulation, EC method con- sists of the in situ generation of coagulants by electrolytic ox- idation of an appropriate soluble anode material (e.g., iron or aluminum) [23, 24]. In an EC process, the coagulating ions are produced ‘‘in situ’’ and it involves three successive stages: (i) formation of coagulants by electrolytic oxidation of the ‘‘sacrificial electrode,’’ (ii) destabilization of the contami- nants, particulate suspension, and breaking of emulsions, Ó 2011 American Institute of Chemical Engineers Environmental Progress & Sustainable Energy (Vol.00, No.00) DOI 10.1002/ep Month 2011 1