SBIR-STTR Award

The objective of this proposal is to demonstrate the feasibility of an innovative design that combines cross-flow filtration (CFF) and Dean Flow surface cleaning to achieve an effective self-cleaning filtration for Armys RO pretreatment. CFF is especially effective for feed flow with a high amount of colloidal solids that are commonly found in surface water. Unlike dead-end filtration, the surface dynamics of CFF does not make the gelatinous colloidal solids extrude through pores which often compromise the performance of filtration. The Dean Flow has a form of double vortices. The shear force of the vortices will prevent contaminants from adsorbing to the membrane wall. At the same time, the flow trajectory tends to push solids and contaminants toward the eye of the vortices, keeping them away from the membrane surface to minimize the fouling. The design also takes advantage of modern tubular membrane filter to engineer the flow path required for Dean Flow generation and to attain the required processed flow quality. The combination of the CFF and Dean Flow minimize the concentration polarization problem commonly found in membrane filtration.

The objective of this proposal is to continue the development of an innovative filter design that combines cross-flow filtration, Dean Flow surface cleaning, a coiled tubular membrane filter (TMF), and an unhoused membrane module into an advanced, robust and simple reverse osmosis pretreatment system. Dean Flow is a secondary flow with a dual vortex form. The vortex profile generates a high shear rate which acts to transport contaminants away from the filter membrane surface to be carried away by the cross-flow. The design takes advantage of the characteristics and performance of modern TMF by coiling the tube to engineer the flow path required for Dean Flow generation in order to attain the required water quality. Taking advantage of the manageable dimensions of the coiled tube (as opposed to a long straight tube) and the simple system operating conditions allows this novel filter membrane module to simply be mounted under a drum or tank cover. In Phase I, the feasibility of a system that combines these features was demonstrated. Phase II will pursue advanced development to refine the design and optimize performance. A full size prototype with a capacity of 100 gallons per minute will be completed for demonstration.