Advantages of Compound Electrocoagulation–Filtration with Calotropis procera for the Treatment of Emulsified Oil in Water

Abstract Emulsified oil removal from water was evaluated using electrocoagulation (EC) with aluminum electrodes coupled to filtration through in naturaCalotropis procera (CP) fibers. The integrated EC–CP system outperformed filtration alone and maintained higher efficiency at increased flow rates than standalone EC. At the highest flow rate tested (6 mL·s–1), it achieved 97 ± 2% oil removal (OR%T), 91 ± 1% chemical oxygen demand reduction (COD%T), and 99.6 ± 0.4% turbidity removal (Turb%T). Higher flow also lowered specific energy consumption to 1.2 kWh·m–3, less than half the value for a flow rate of 2 mL·s–1. Overall, operating at elevated flow rates reduced average energy cost (Cenergy) by 72% and operational cost (Cop) by up to 67%, because larger volumes could be treated while preserving higher OR% than pure EC. The best combined performance for COD%T, Turb%T, and OR%T occurred at 6 mL·s–1 and an electrode inversion time (ti) of 20 s.