A Diffusion Membrane for Separation of Hydrocarbons from Water Streams

ABSlRACT Over the years a variety of technologies have been used to remove organic contamination from water. Unfortunately, most of these techniques are either too expensive or too complicated to operate and, in some cases, cause secondary pollution effects. Various membrane processes have been developed and tried but, unfortunately, little success has been realized. Membrane processes are gaining increased acceptance in a variety of separations because they are relatively simple, require less energy to operate, can easily be scaled up, and because they can achieve a high degree of selectivity of separation. However, they have had several drawbacks when applied to hydrocarbon-water separations, such as degradation from petroleum products, fouling, inadequate rejection of petroleum hydrocarbons, and high failure rates, resulting in high replacement costs. Described herein, is a new membrane technology that has been shown to be extremely effective in separating hydrocarbons from water streams. This membrane separation process uses a proprietary membrane called EXTRANTM, which is composed of completely natural cellulose made by a special SDI process. Membranes are in the form of hollow fibers that are potted into suitable pressure vessels and incorporated into a system. The EXTRAN membrane is resistant to a vast array of hydrocarbons and organic solvents. Being a true diffusion membrane, it has no pores to clog. These properties, in combination with high tangential velocities through the bore of the membrane, allows continuous operation with little or no chemical cleaning. Presented are test data obtained by the company in its laboratories as well as results obtained by others. The results obtained to date indicate that the new membrane system shows good potential for the treatment of a variety of hydrocarbon contamhated wastewaters. Applications being exploited include treatment of tank water bottoms, offshore produced water, and a variety of other liquid waste streams.