Produced water (PW) is oily water that is co-produced during oil and gas exploration and production. In the United States, PW accounted for 88% of the total volume of exploration and production material brought to the surface by the oil and gas industry in 2007. The total volume of PW generated from most of the nearly 1 million actively producing oil and gas wells in the United States in 2007 was estimated to be about 21 billion barrels (bbl). Therefore, identifying and implementing appropriate beneficial uses for PW should provide overwhelming benefits for local communities and ecosystems and provide oil and gas companies with flexible, cost-saving water management options. Conventional wastewater treatment technologies such as coagulation, flocculation, air flotation and gravity separation normally cannot meet the high purity requirements for discharge of PW. There is a growing tendency to use membrane technology for PW treatment. Although membranes can treat PW, their widespread use is hindered by a decline in permeate flux experienced as a result of fouling.