respectively. The sulfur content of the animal fat methyl esters fitted the ASTM D6751 (S500) biodiesel standard while they were not suitable to EN 14214 biodiesel standard. The reason of the high sulfur content of these esters may be the sulfuric acid usage in the biodiesel production. However, in some studies (Çolak et al., 2005; Rashid et al., 2009), the sulfur content of the vegetable oil or animal fat methyl esters did not fit the EN 14214 sulfur standard (10 ppm) although sulfuric acid was not used in those studies. This shows that sulfur containing compounds may still be in the biodiesel after washing or purifying process. Therefore, water-washing or other purifying methods are critical for sulfur removal.
The results showed that the fuel properties of the methyl esters produced in the laboratory and pilot plant were a little different but close to each other. The reason for this may be higher amount of oil usage or production and refining process in the biodiesel pilot plant. In addition, another reason may be that the fuel properties of