Kitchen wastewater degradation using electrochemical reactor

Kitchen wastewater (KW) constitutes a significant fraction of global wastewater and contains bio-refractory organics that require effective treatment. This study investigates the treatment of KW using an electrochemical bipolar disk stack reactor equipped with electronic waste (ewaste) derived lead dioxide (PbO₂)-coated graphite electrode. The influence of critical operating parameters such as applied voltage, electrolyte concentration, and volumetric flow rate on chemical oxygen demand (COD) removal was examined by following the response surface methodology (RSM) based central composite design (CCD). Results showed that COD removal increased with voltage and electrolyte concentration but decreased with flow rate, with voltage being the most significant factor. The optimized conditions - 12 V, 5 g/L NaCl, and 0.25 mL/s flow rate - achieved 84% COD reduction with an energy consumption of 0.0134 kWh/g COD. Additionally, a theoretical model was developed to predict COD removal efficiency. The results demonstrated superior catalytic activity and stability of the e-waste-derived PbO₂-coated graphite electrode.