Eloksal işlem yapan fabrikalarda düşük maliyetli kimyasal kullanımı ile sülfat giderimi

The surface treatment of and by metals dates back to early man using gold decoratively before 4000 BC. One of the surface treatment methods is anodic oxidation. Anodic oxidation, or anodizing, is an electrolytic process for producing very much thicker oxide coatings whose improved physical and chemical properties have greatly increased the field of application for aluminum. Sulfuric acid soon became and, remains the most common anodizing electrolyte. In anodizing process, 18-20% concentration of sulfuric acid is used as the electrolyte. Due to sulfuric acid ionize to H+ and SO42-, anodizing wastewaters contain high sulfate concentration. High concentrations of sulfate in drinking water may cause transitory diarrhea. In Turkey, sulfate concentration limit is 250 mg/L in drinking water and 1700 mg/L for the industrial plants at the organized industrial zones (OIZ, industrial park). This study aims to investigate sulfate removal from an acidic wastewater, which is obtained from an Aluminum Profile Production and Anodizing Plant located in Bilecik. The experiments were performed under the same conditions of the treatment facility of the factory. BaCl2.H2O, which is currently used in the treatment facility of factory, was applied with different amounts. CaCl2 and KCl were selected as alternative chemicals to BaCl2.H2O and were used with different amounts in the experimental trials. Besides, the effect of the flocculants and the basic effluent, which is used for neutralization, was also investigated. As an important result of the study, it was determined that chemical costs of the treatment facility can be decreased by changing the chemical type and amounts. In the first section; the aim, scope and the literature about the investigation of sulfate treatment methods were given. In the second section; theoretical knowledge about anodic oxidation process and aluminum plant information were presented. In the third section; the chemical precipitation by BaCl2.H2O, CaCl2, KCl, and neutralization with basic effluent methodologies were explained. In the fourth section; the results of experiments were given and they were comparatively assessed. In the fifth section, the evaluation of experimental results was presented.