Fluid Mechanics of High Shear Rotating Disk Membranes

Funding Agency: Texas Advanced Technology Program, Lyonnaise des Eaux-Suez

Principal Researchers: Christophe Serra, Jim Engler

Computational Fluid Dynamics (CFD) simulation of flow near a rotating membrane disk

The current global market for membrane processes exceeds $1 billion annually. Applications for membrane technologies include treatment of production waters from gas and oil well operations; hazardous and industrial waste cleanup (Texas is the nation's largest producer of hazardous wastes, ­ 22%); water desalination/reuse; resource recovery, pollution prevention, medical and pharmaceutical separations; pretreatment of cooling waters for power plants; water supply to military personnel in the field or on naval vessels; and water treatment in the beverage industry. In this effort, Rice Unversity researchers have been studying the fluid dynamics of an innovative rotating disk membrane process. The rotating disk membrane filter is a high shear rotary crossflow device composed of hollow membrane-covered disks stacked on a hollow shaft which turns inside a pressurized vessel. This liquid separation technology provides for continuous three-way separation of water, materials lighter than water (e.g., oils), and heavier-than- water materials (e.g., suspended solids). Permeation into the membrane disks occurs due to the pressure applied within this vessel to the outside of the membrane disks. Rotation of the disks produces a shear at the membrane surface which scours deposited materials from the membrane, thereby maintaining low resistance to flow through the membrane. However, centrifugal force within the membrane disk creates a back pressure which may reduce the efficiency of this process. Computational fluid dynamics and laboratory observations of particle transport and deposition are being used to arrive at a better understanding of the process and to optimize design.