Enhanced chromium removal from tannery wastewater through electrocoagulation with iron electrodes: Leveraging the Box-Behnken design for optimization

This study is focused on reducing total chromium level in tannery wastewater through the electrocoagulation process, in order to comply with the maximum permissible limits (MPL) and to determine the effects from its main operating factors. For this purpose, a batch electrocoagulation reactor was manufactured using iron electrodes. Next, the response surface methodology was applied in the experimental design using a Box-Behnken design (BBD) with three factors: current intensity, treatment time, and $pH$ level. In addition, the total chromium removal percentage was taken as a response variable. The corresponding statistical analysis revealed that the treatment time, current intensity, and $pH$ level variables were significant at a confidence level of $P-value<0.05$. Obtained in this study for a $99\%$ total chromium removal were: current intensity $\left(I\right)=2.9A$, time $\left(t\right)=18.1\min$, and $pH=5.6$. Our results indicated that the electrocoagulation process effectively removes total chromium from tannery effluents up to MPL values.