TREATMENT OF OILY WASTES USING HIGH-SHEAR ROTARY ULTRAFILTRATION

The high-shear rotary ultrafiltration (UF) system uses membrane rotati on to provide the turbulence required to minimize concentration polari zation and flux decline. The high-shear UF system was effective in con centrating oily wastes from about 5% to as high as 65%. The decoupling of turbulence promotion from feed pressurization/recirculation by rot ating the membrane was the primary reason for the improvement in perfo rmance over that observed with conventional UF systems. Transitional a nd gel layer oil concentrations (20% and 50-59%, respectively) were hi gher than values reported in the literature. Permeate flux was depende nt on the temperature and rotational speed. Flux increased by about 45 % when the temperature was increased from 43 to 60 degrees C. A larger decrease in waste viscosity, over that predicted for water alone, and increased oil droplet diffusivity were hypothesized as reasons for th e stronger than expected flux-temperature relationship. The flux-rotat ional speed (omega) relationship was described by J = f(omega)(0.90); however, the gel layer exhibited stability with increasing omega. The ceramic membrane was superior to the polymeric membrane in regards to permeate flux and quality as well as cleaning and durability.