Treatment of aqueous effluents from the biodiesel industry using membrane technology

ABSTRACT The wastewaters from biodiesel production are generated mainly in the washing process, in this step the contaminants of biodiesel are eliminated in order to the obtained biodiesel meets with the internationals regulations. These wastes contain impurities such as methyl ester, residual oil, mono and diglycerides, soluble salts, catalyst, soap, glycerol and alcohol. The aim of this study is the application of membrane technology for the treatment of aqueous wastes from biodiesel industry. By means of the phase inversion method was synthesized a membrane of UF using a 17wt% of polyvinylidene polyfluoride (PVDF) and 8,5wt % polyvinylpyrrolidone (PVP) casting solution. The filtration essays were performed in a cross flow cell. The operational conditions were: T= 20°C, Δp=0.4-1 bar y v=0.5-1 m/s. A synthetic sample prepared in the laboratory and a real effluent sample from biodiesel industry was employed as membrane feed. At constant feed stream speed, the permeate flux decreases with increase of pressure (mass transfer controlled region). While an increasing in the permeation speed at constant pressure the permeate flux gradually increases. With increasing speed, membrane surface cleaning increases due to solutes are swept tangentially away. It was concluded that the studied membrane retains between 83-100% of oils and fats, and between 20-40% of DQO, whereas pH and TSS remain constant.