Performance Investigation of an Electrocoagulation Reactor with Electrodes’ Polarity Crossly Oriented in Emulsified Oil Separation

Abstract

This work aimed to separate emulsified oil from oily sewage by electrocoagulation (EC). The research was carried out in a continuous system with aluminum electrodes. The effect of electrodes placement, including tilt angle of parallel-plate electrodes (APE) and electrodes’ polarity orientation (POE), on EC performance (oil removal and energy consumption) was studied. A novel reactor, within which the electrodes with polarity crossly oriented (PC) was compared to that with electrodes’ polarity identically oriented (PI) under different running conditions, as the APE, applied current density, flow rate, and electrode distance. To throw light upon the difference of reaction rate between PC and PI performance, a first-order kinetics equation was established. The results show that the PC system was more efficient than the PI system, particularly at lower current densities. At optimum conditions (current density of 140 A/m2, electrolysis time of 140 min, a flow rate of 5 L/h, and APE of 76°), 97.6% of emulsified oil was removed in the PC system with the energy consumption of 0.869 kW·h/m3. By contrast, the removal efficiency in the PI system only reached 91.4%, which was 6.2% lower than that in the PC system. Besides, it can be found that the entire EC process can be divided into two stages: start-up stage and steady state. The higher the current density and the flow rate, the shorter the start-up time. Evaluation of the effects of APE indicates that there exists an optimum tilt angle of electrodes at which the EC performance was better than any other tilt angles studied.

Enhanced chromium removal from tannery wastewater through electrocoagulation with iron electrodes: Leveraging the Box-Behnken design for optimization

“…Treatment times have a direct effect on electrocoagulation process efficiencies [ 33 ]. This parameter influences the production rate of coagulant, , and , as well as affects the cost-effectiveness of the process [ 33 , 34 ]. Hence, we varied the treatment time in the range of .…”