Wastewater treatment using ultrafiltration at a vegetable oil factory

An investigation of wastewater treatment by ultrafiltration (UF) is introduced. In the experiments a UF membrane (UFPHT20-6338) and samples of Behshahr Ind. Co. wastewater as feed were used. The effect of operating conditions such as pressure difference, cross flow velocity, shear stress, temperature, concentration of organic components and pH on permeation flux, flux decline and fouling resistance were studied. The results show that a pressure difference more than 3 bar, high cross flow velocities (depending on economic considerations), a temperature of 30°C and a pH of 9 are the best operating conditions. Analysis of the wastewater treated by UF represents 91%, 87%, 100%, 85% and ! 40% reduction in COD, TOC, TSS, [PO4 3] and [Cl!], respectively. Reduction of the phosphate concentration by UF is very considerable.

According to the results, it can be concluded that UF treatment is a possible and acceptable method for vegetable oil wastewater. More suitable properties of the permeate, easier operating conditions, a greater ability to combine with other methods (chemical and biological) and easier control of the system are considerable advantages of UF. In addition, a slight dependence of permeate properties on the feed properties is another advantage of this method. In other words, finite variations in feed parameters do not seriously affect product properties. The results show that a pressure difference of more than 3 bar, high cross flow velocities, a temperature of 30°C and a pH of 9 are the best operating conditions.