Treatment of Oily Wastes Using High-Shear Rotary Ultrafiltration

Abstract

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 flux-rotational speed (ω) relationship was described by