The reduction of impurities in the biodiesel can be achieved by applying further purification steps, subsequent to decantation. Traditionally, the most widely used method is wet scrubbing (wet washing), which consists of using hot water due to the high solubility of these contaminants in water, coupled with the low cost, simplicity, efficiency and abundance. The disadvantage of the method, besides the formation of the emulsion, preventing the separation of esters and allow the formation of free fatty acids and soap, is the large volume of wastewater generated. In this last case, it can be circumvented by applying dry purification methods which do not use water to wash the biodiesel.