Abstract: The method of extracting single cell protein from spent liquor of citric fermentation was studide.The optimum conditions were obtained.Chitosan concentrate 90mg/kg pH4.5,temperature 45℃,stirring for 20min.As a result the yield of single cell protein was up to 97.8%.The COD of the spent lipuor was decreased by 31 .7%.

Key words: Spent liquor, Single cell protein, Extraction chitosan