Application of a Box-Behnken design to the optimization of margin processing conditions by the electro-Fenton process on different anodes using solar energy

This study focuses on the treatment of margin (olive mill wastewater) using the electro-Fenton process with different anodes powered by solar energy. Iron from pyrite is used as a catalyst, and hydrogen peroxide is produced in situ by bubbling air into the effluent. A three-factor Box-Behnken design is employed for optimization. The results show that a boron-doped diamond (BDD) anode achieves a chemical oxygen demand (COD) reduction rate of 98.71 % under the following conditions: current of 0.7 A, pyrite mass of 0.3 g, and electrolysis time of 90 min. Using a platinum anode, a COD reduction rate of 87.0 % is obtained with a current of 0.5 A, a pyrite mass of 0.3 g, and an electrolysis time of 75 min. Energy consumption is 10.35 kWh m⁻³ for BDD and 6.25 kWh m⁻³ for Pt, giving an operating cost of around 1.13 $ m⁻³ and 0.682 $ m⁻³ for the BDD and Pt respectively. This study demonstrates that the BDD electrode yields superior results compared to a flat platinum anode when using solar energy.