Ultrafiltration (UF) membrane separation is one of the largely used technologies for macro molecular solutes separation from aqueous streams especially for effluent treatment of process industries. A series of cellulose acetate (CA) blended with activated carbon, ultrafiltration (UF) membranes were prepared by the phase-inversion technique in 99.5/0.5, 98.5/1.5 and 97.5/2.5% blend compositions. Prepared membranes were subjected to morphological studies (using SEM and AFM), UF characterization study and thermal stability study. The blend membranes exhibited differences in morphologies, porosities and properties due to the activated carbon (AC) addition. With increase in AC concentration in the membrane composition, the membranes exhibited excellent water permeability, hydrophilicity, thermal strength and good anti-fouling ability. Results clearly indicated the improved characteristic features of 97.5% CA - 2.5% AC blend membrane in comparison with other synthesized UF membranes. Subsequently, performance study on the 97.5% CA - 2.5% AC blend membrane was carried out by subjecting the blend membrane for a typical tannery effluent treatment to study the reduction of BOD, COD and sulphates in the effluent. Performance results of the blend membrane were compared with the performance of pure CA membrane.