Experimental studies of tannery wastewater treatment by combined electrocoagulation and ultrasonication processes using response surface methodology optimization

In this study, tannery wastewater treatment using a combined electrocoagulation–ultrasonication process and the optimization of operating parameters by response surface methodology were performed. The electrocoagulation process was conducted using aluminum electrodes by varying current density, pH, and time. The ultrasonication process was studied by varying probe diameter, power rate, and time. Mathematical models showing the effects of parameters on chemical oxygen demand reduction during the process were also developed with an average deviation of 6% compared to the experimental values. The optimum operating time for the electrocoagulation and ultrasonication in the combined process was found to be 60 and 45 min, respectively. Results indicate that a maximum chemical oxygen demand removal of 69% was observed by the combined process. Sludge obtained from the electrocoagulation process was used as a fertilizer additive in soil for plant seedlings. The nitrogen content in the sludge mixed soil has increased by 46% within 4 weeks compared to raw soil which provides additional growth supplements to the plant. The findings demonstrate that the multimodal treatment process is capable for the treatment of tannery wastewater. Further, response surface methodology is identified as a potential tool for the optimization of variables during the treatment process.