Effect of voltage and pH on the electrocoagulation process for chemical oxygen demand removal in wastewater from Mollendo, Peru

The discharge of urban wastewater to receiving bodies represents a growing environmental threat in cities such as Mollendo, Peru, where the absence of a treatment plant has caused the discharge of untreated effluents into the sea, causing a serious ecological impact. Therefore, the objective of this study is to evaluate the influence of voltage and pH on the electrocoagulation process for the removal of Chemical Oxygen Demand (COD), whose initial concentration is approximately 670 mgL-1. A system of 5 L batch reactors with iron electrodes was used, which presented fast removal kinetics, achieving a 94.4% reduction of COD in only 20 minutes under optimal conditions (pH 7.5 and 7 V) complying with local regulations. The rate constant around 0.1204 min-1 indicates a high level of accuracy of the mathematical model. In addition, the operating cost was estimated at 0.3919 USD/Kg COD which corresponds to energy consumption of 0.363 USD/Kg COD. These results demonstrate the potential of electrocoagulation as an effective, economical and sustainable alternative to mitigate water pollution in coastal urban environments. Keywords: electrocoagulation, pH, removal, time, voltage, wastewater.