The high-shear rotary ultrafiltration (UF) system uses membrane rotation to provide the turbulence required to minimize concentration polarization and flux decline. The high-shear UF system was effective in concentrating oily wastes from about 5% to as high as 65%. The decoupling of turbulence promotion from feed pressurization/recirculation by rotating the membrane was the primary reason for the improvement in performance over that observed with conventional UF systems. Transitional and gel layer oil concentrations (20% and 50-59%, respectively) were higher than values reported in the literature. Permeate flux was dependent on the temperature and rotational speed. Flux increased by about 45% when the temperature was increased from 43 to 60°C. A larger decrease in waste viscosity, over that predicted for water alone, and increased oil droplet diffusivity were hypothesized as reasons for the stronger than expected flux-temperature relationship. The ceramic membrane was superior to the polymeric membrane in regards to permeate flux and quality as well as cleaning and durability.

Reprinted with Permission from Spintek Filtration, Inc.