Development of a Membrane System for the Shipboard Processing of GrayWAter/Oily Water

For nearly 20 years the Navy has been facing the problem of limitations of graywater and oily waste discharge into the ocean and/or harbors. One obvious method would be a lightweight unit composed of a membrane system capable of successfully processing these complex waters. Membrane systems composed of spiral elements, hollow-fine fibers and ceramic filters that have been tested over this period have all suffered severe flux declines operating on these waters. This Phase I proposal is directed toward demonstrating the feasibility of utilizing a low-fouling hydrophilic, ultrafiltration or nanofiltration membrane, incorporated in a high velocity spinning device designed to minimize fouling and promote ease of cleaning, for the processing of graywater and oily wastewater feeds aboard ship. This rotating membrane system utilizes the process of centrifugal action and shear forces to prevent membrane fouling common to spiral-wound elements. The open channels in the unit eliminates the need for mesh-type turbulence-promoting spacers that can plug with solids and lower the system performance. This leads us to conclude that fouling should not be a high-flux membrane developed during this program offers excellent promise of success.