Industrial wastewater treatment by electrocoagulation–electrooxidation processes powered by solar cells

• The EC and EO achieved a TOC removal efficiency of 99%.
• The use of copper in EC stabilizes the system.
• The electrooxidation process (BDD/Cu) promotes the demineralization of water.
• The electrooxidation is a clean process that avoids the CO2 emissions.
• The solar cells supply sustainable energy to the electrochemical processes.

The goal of this research was the elimination of the chemical oxygen demand (COD), total organic carbon (TOC), color, and turbidity from the industrial wastewater from an industrial park by applying electrocoagulation (EC) and electrooxidation (EO) processes powered by solar cells. The EC process was carried out in a batch monopolar electrochemical cell; copper was used for the anode and cathode electrodes, with an area of 0.00125 m2, and solar cells supplied the system with 1–3 A of current intensity. The COD reduction was 80% at pH 2 and 89% at pH 4, and a removal efficiency of 97% and 91% of color and turbidity, respectively, were achieved; however, TOC reduction achieved was only 48%. In order to improve the removal of TOC, an EO treatment was applied after the EC process. The EO was carried out in batch cells using a boron-doped diamond (BDD) anode and a copper cathode. The maximum removal efficiency was 70.26% of TOC and 99.7% of COD, with EC + EO processes. Color and turbidity removal were 100% and 95%, respectively. Aside from the strong oxidation capability of the hydroxyl radicals generated, the presence of active chlorine in the solution contributed to COD removal via indirect oxidation.

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