Advanced Membrane System for Graywater Treatment

Fouling is a serious problem encountered when membranes are utilized to treat shipboard graywater. Its resolution is particularly critical aboard naval vessels due to space limitations. A hybrid membrane is proposed which is capable of producing an effluent with a biological oxygen demand (BOD) and suspended solids less than 30 ppm with 95% rejection of oils, surfactants, etc. The membrane features a unique, non-absorbing layer fixed upon the surface of the polymeric ultrafiltration membrane substrate. Not only does this layer inhibit fouling but it facilitates cleaning of the membrane surface and is stable to macromolecular spatial rearrangement. Consequently, system longevity is extended. Although this membrane can be used for a variety of applications in which adsorption of feed species and concomitant membrane fouling limit the utility of ultrafiltration membranes, this research will focus upon treating the shipboard graywater. A Phase I research program is needed to characterize membrane configurations and to evaluate operation parameters on graywater treatment. The primary objectives are to prepare membranes with specific performance properties, to verify separation efficiencies, and to demonstrate utility with simulated waste feeds in a bench scale test loop. In Phase II, a prototype scale system will be constructed to demonstrate long term operability.