Electrodialysis Treatment of Refinery Wastewater

Abstract

Water is fundamental in the oil refining process, with on average 0.9 m3 water being consumed per m3 of oil processed. Water is used in the oil refining process for steam generation, cooling systems, potabilization, fire fighting, the removal of contaminants and services in general. Industries are having difficulties in obtaining water due to the growing scarcity and pollution of water, with increasing treatment costs as a consequence, which limits increases in productivity. It has therefore become necessary that industries implant a water management system, including its rationalization with process modification, choosing the best treatment method for discharge or reuse. For many industries, management systems and water reuse may be an important factor contributing to their survival. The wastewater generated in refineries is sent to a treatment plant, to reach the necessary quality for discharge. The composition of the wastewater varies greatly and depends on the complexity of the refining process. The reuse requires additional treatment processes and the selection of the method will depend on the characteristics of the wastewater and on the required water quality. Wastewater treatment processes using membranes are being increasingly used because of their high efficiency, small installation area, low consumption of chemicals and increased automation. Among the different membrane processes, electrodialysis has been increasingly employed in the industry for partial desalination aiming water reuse. In refineries, the electrodialysis reversal process is not yet widely used, but it has great growth potential. The evaluation of the pilots and industrial units in operation have shown the advantages over similar desalination processes, such as greater robustness, operational reliability and simplicity and less necessity of wastewater pre-treatment. This chapter will present an overview of the use of electrodialysis for water reuse in refineries.