Performance evaluation of an integrated photo-Fenton – Electrocoagulation process applied to pollutant removal from tannery effluent in batch system

The treatment of tannery industrial effluent (TIE) by integrating the widely used photo-Fenton and electrocoagulation (EC) processes was investigated. The optimization of the photo-Fenton process by using solar irradiation was made performing a full 33 factorial experimental design. An irradiation time of 120 min for the photo-Fenton reaction was more favorable to pollutant removal in acidic medium using Fe2+ concentrations ranging from 0.4 to 0.5 g L−1 and H2O2 concentrations ranging from 15 to 30 g L−1. Nonetheless, a reduction in sludge production and a minimum residual content of hydrogen peroxide were attained within 540 min of irradiation time, with 0.4 g L−1 Fe2+ and 15 g L−1 H2O2 initial concentrations, with almost the same efficiency of COD, color, and turbidity removal obtained under the optimal experimental conditions. When the pretreated TIE samples were submitted to an EC process, the results of inorganic pollutants removal were better than with the conventional method (use of a combination of filtration, chemical coagulation, and sedimentation processes). In addition, the application of the integrated photo-Fenton and EC process for TIE treatment is cheaper than the conventional one. All the results showed that the integrated photo-Fenton and EC process could be applied as an efficient low-cost alternative treatment for the removal of organic and inorganic pollutants from tannery industrial effluent with a low environmental impact.

► Integrated processes were applied to remove pollutants from tannery effluents.
► Both photo-Fenton and electrocoagulation processes were optimized and integrated.
► A sludge yield reduction was studied searching a minimum environmental impact.
► A minimum H2O2 content was investigated to drive an efficient low-cost treatment.
► High pollutant removals were attained with values below the allowed environmental limits.