The results of lipid transesterification from liquid–liquid extraction were compared with the results from drying by standard MgSO4·H2O method in order to verify that the process did not affect the yield of biodiesel and the composition of FAMEs. The optimised liquid–liquid extraction gave 26.7 ± 0.1% of lipid (on the basis of dry sludge), the saponifiable obtained after transesterification was 72.0 ± 3.0% (on the basis of lipid) and the value of biodiesel was 19.2 ± 0.1% (on the basis of dry sludge). These values are higher than those obtained by standard method (25.2 ± 0.2% of lipid, 69.7 ± 0.7% of saponifiable and 17.6 ± 0.2% of biodiesel)