A laboratory study was carried out to enhance biofuel yield of marine microalgae Tetraselmis chuii, Chaetoceros muelleri and Isochrysis sp. (clone c Iso), using an aqueous extract of secondary recovered sewage sludge (SS). In this respect, we compared the intracellular lipid accumulation in cells grown on controlled to the treated with SS cultures, both quality and quantity. The gravimetric data showed an obvious increase of total lipids in the treated cells 13.16, 1.65 and 1.8 times for T. chuii, C. muelleri and Iso. sp. respectively. In addition, the algal oil increased 16, 1.73 and 5 times in the same order. Fatty acid methyl esters of the controlled  growth cultures are dominated by C14:0, C16:0, C16:1, C18:0, C18:1, C18:2, C18:3, C18:4 and C22:6. However, the treated ones showed a significant variation in the concentration of both total lipids and oil fatty acids. Moreover, some fractions are disappeared, while others are newly synthesized. The results suggest that the application of sewage sludge could enhance the accumulation of algal lipid, oil, and improve the quality of biofuel produced.