Independently of the extraction time, as it was expected,the yield of lipids increased after each extraction stage when increasing the amount of solvent. However, for volume ratios of 2:1, 1:1 and 1:2, 60 min of extraction time did not show significant difference between the lipid yields, after the third stage of extraction. This suggests that the quantity of hexane used for a ratio 2:1 for 60 min was enough to achieve 27% of lipids based on dry sludge (91% of the attainable lipid value).