Electrocoagulation Treatment of Oily Wastewater in the Oil Industry

Abstract

Electrocoagulation has turned out to be a rapidly growing area of wastewater treatment due to
its ability to remove contaminants that are generally more difficult to remove by filtration or
chemical treatment systems. These pollutants may include emulsified oil, petroleum
hydrocarbons, suspended solids, and heavy metals. In this novel technology, metal cations are
released into the wastewater through dissolving metal electrodes. Simultaneously, beneficial
side reactions can help in removing flocculated material from the water.
Oily wastewater represents a dangerous threat when discharged to the environment; therefore
treating it becomes vital in oil industry. This research has investigated electrocoagulation as a
simple, effective and economic technique for treatment of such wastewater. Bench scale reactor
was used to evaluate the factors that may affect the treatment of oily wastewater. Aluminum
was used as a sacrificial anode. Electrodes were arranged at different configurations to select
the optimal one. Other tested operation parameters include time of treatment, current density,
distance between the electrodes, and the electrolyte concentration of the emulsion. The
experimental results indicated that electrocoagulation was very efficient and able to achieve
94% turbidity removal in less 60 min, pH:7, current density of 45 (A/m2).
Also the effect of initial concentration of oil (100-1000 ppm) in wastewater, applied voltage
(10-20 v), the dose of NaCl electrolyte (0-1 g) and temperature (35-60 oC) were optimized.
What distinguishes this work is the the type of the electrodes configuration. Circular horizontal
Al/Al electrodes (Ø12 cm) with 17 holes (Ø7 mm) have been found to give the best
electrocoagulation environment and thus optimum results. The associated electrical energy
consumption is 1.6 kW h/m3 for flotation times of 60 min.