In the wet washing process, for every 100 L of biodiesel produced some 20 L of wastewater are produced [5]. The water content of the biofuel after the washing step (mentioned in point iii), is around 0.15% [6,7]; this value is above the maximum set by the standards (0.05%) and it’s therefore necessary to introduce a later stage of centrifugation and/or drying under vacuum conditions. The wastewater due to its physicochemical characteristics, should be treated before the final discharge in order to reduce the environmental impact. The washing water is characterized by high values of pH, COD (chemical oxygen demand), BOD (biological oxygen demand), fats and oils, needing a complicated and expensive biological treatment and thus increasing operating costs [5,8].