Investigation of the treatability of Tunceli organized industrial zone wastewater with electrocoagulation process

In this study, the treatment of wastewater from the Tunceli Organized Industrial Zone (OIZ) using the electrocoagulation process was investigated. The main aim of the research is to determine the optimal operating conditions that provide the highest chemical oxygen demand (COD) and color removal efficiencies in the electrocoagulation process while minimizing operational costs. In the study, the effects of three independent parameters—current density, inter-electrode distance, and reaction time—on COD removal, color removal, and operational cost were evaluated using the Response Surface Methodology (RSM)-based Central Composite Design (CCD). The experimental work was designed and analyzed using Design Expert 7.0 software. The modeling results showed that the second-order (quadratic) models developed for COD removal, color removal, and operational cost were statistically significant and reliable. The correlation coefficients (R²) were found to be 0.9425 (COD removal), 0.9255 (color removal), and 0.9899 (operational cost), indicating a strong correlation between the experimental data and model predictions. As a result of optimization studies, the optimum conditions for COD removal were found to be 19.86 mA/cm² current density, 4.84 cm inter-electrode distance, and 79.49 minutes reaction time, achieving a COD removal of 68.07%. For color removal, the optimum conditions were 5.41 mA/cm² current density, 5.15 cm inter-electrode distance, and 68.47 minutes reaction time, resulting in 99.93% color removal. The minimum operational cost was found to be 0.098 USD/m³ at a current density of 6.82 mA/cm², inter-electrode distance of 2.58 cm, and reaction time of 10.29 minutes. Additionally, under the conditions providing 68.07% COD removal, a 98.34% color removal and an operational cost of 0.125 USD/m³ were achieved. As a result of this study, it was demonstrated that when optimized with suitable parameters, the electrocoagulation method can effectively treat industrial wastewater, such as that from Tunceli OIZ, and provide a sustainable treatment alternative with low operational costs.