Abstract

Petroleum industries are burdened with the problem of handling large quantities of sludge having properties that depend on the nature of the crude oil, the processing capacity, the down-stream capacities, and the design of effluent treatment plants. Oily sludge is a complex mixture of hydrocarbons, water, metals, and suspended fine solids. This composition makes management of the sludge a complicated and costly undertaking. The objective of this research is to develop a technique that would significantly improve the separation of phases so as to allow for their further reuse. This investigation focused on the application of electrokinetic phenomenon for the remediation of oily sludge. To assess the effect of surfactant on the electrokinetic mobilization of organic contaminants in oily sludge, an amphoteric surfactant was used. Tests were performed in a series of electrokinetic cells with different electrical potentials. During 32 days of the experimental, electrical parameters and pH were measured daily, while samples collected at strategic intervals were analyzed by UV/VIS and FTIR methods. This research lies at the forefront of electrokinetic technology and embraces a combination of several processes including electrocoagulation, electrocoalescence, desorption, electrophoresis, and electroosmosis. The results obtained permit an assessment of the thermodynamics of the proposed process and introduce new theories on the behavior of the colloidal component of oily sludge under different electrical potentials. The results demonstrated an excellent separation of phases; these consisted of water, hydrocarbon, and solid phases. The recovered solid phase exhibited high hydrocarbon content, so it could be reused. The separated liquid hydrocarbon could be reused in other processes. Some volatile hydrocarbons were released during the process. Advantageously, these gaseous hydrocarbons may be captured and burned as fuel. The results showed that the separated water had a low concentration of hydrocarbon, suitable for sending to the wastewater treatment plant. The method allows for the recycling of the hydrocarbon residue of a waste stream into a usable refinery product by achieving a 63% reduction in water content, and, thereby, reduces or eliminates the potential liability for environmental contamination arising from the disposal of waste stream products.