NOVELTY - A microalgal biomass is extracted. Delipidized biomass is separated from microalgal oil solution. Microalgal oil is treated with methanol and super-acid solid catalyst. The obtained 5-chloromethyl furfural is extracted in toluene. The obtained aldolic condensate is mixed with reaction product of methyl esters of fatty acids. The mixture of aldolic condensate and hydrogenated and hydrocracked esters is subjected to hydrodeoxygenation, and hydroisomerized. A fraction of obtained mixture of n-isoalkane is separated, to obtain aviation biofuel.    USE - Preparation of aviation biofuel from microalgal biomass (claimed).    ADVANTAGE - The method enables economical preparation of aviation biofuel from microalgal biomass by processing in an integrated system. Both microalgal oil and component polysaccharides of microalgal biomass are turned into aviation biofuel. The valorization of protein fraction in the algal biomass is achieved as proteinic hydrolyzate which is recycled in mixotrophic cultivation of microalgae as a source of nitrogen, or used as foliar nitrogen fertilizer for plants. Recycling of the glycerin resulting as by-product from the processing of microalgal oil, in mixotrophic cultivation of microalgae as a carbon source, is achieved.    DETAILED DESCRIPTION - A microalgal biomass with dry content of 19.11-21.43%, is extracted in an ultrasound extractor with a solvent at 62-69 degrees C. The delipidized biomass is separated by centrifugation from the microalgal oil solution, from which the extraction solvent is removed by distillation. The microalgal oil is treated with 44.34-54.32 wt.% methanol and 5-6 wt.% super-acid solid catalyst. The reaction mass is maintained under stirring at temperatures at which the water resulting from the esterification of fatty acids is separated from methanol in a rectification column and removed. Methanol is recirculated, until the acidity index drops to less than 1 mg potassium hydroxide/g. The super-acid solid catalyst is removed by filtration, and the filtrate is treated under stirring with 6 wt.% calcium oxide and maintaining the transesterification temperature at 65-70 degrees C for 3 hours. Calcium oxide is removed by filtration, and raw glycerin (1) is separated by decantation from the filtrate from the methyl esters of fatty acids (1), and is then treated under stirring with 3 wt.% calcium oxide and maintaining at 65-70 degrees C for one hour. Calcium oxide is removed by filtration, and raw glycerin (2) is separated by decantation from the filtrate from the methyl esters of fatty acids (2). Raw glycerin (1) is mixed with raw glycerin (2). Methanol is removed by distillation. The resulting glycerin is recirculated in the process of mixotrophic cultivation of algae, as a source of carbon. The delipidized biomass is treated under stirring with 37% hydrochloric acid. The obtained 5-chloromethyl furfural is extracted in toluene. Toluenic acid is separated by decantation from the aqueous solution of proteinic hydrolyzate, which after purification is recycled in the process of mixotrophic cultivation of algae, as a source of nitrogen. Toluene is removed by distillation from 5-chloromethylfurfural solution, which is then treated with methanol at ambient temperature. The excess methanol is removed to obtain 5-methoxymethylfurfural which is condensed with acetone in a volume ratio of 2:1 in the presence of sodium hydroxide as catalyst, to obtain an aldolic condensate. The aldolic condensate is mixed with the reaction product of the methyl esters of fatty acids after being hydrogenated with chromium-barium catalyst at 180-280 degrees C and 30-200 atm, and volume velocity of methyl esters of fatty acids of 0.10-0.75 hour-1, volume ratio of hydrogen to methyl ester of 100-5000 mL/mL, and hydrocracked on cobalt-molybdenum/ gamma -alumina catalyst at 325-425 degrees C and 20-90 atm, and volume velocity of liquid of 0.1-0.9 hour-1, volume ratio of hydrogen to raw material of 500-3500 mL/mL. The mixture of aldolic condensate and hydrogenated and hydrocracked esters is subjected to hydrodeoxygenation on tungsten-molybdenum/ gamma -alumina granulated catalyst at 300-380 degrees C and 20-800 atm, and volume velocity of liquid mixture of 0.1-0.8 hour-1, volume ratio of hydrogen to liquid mixture of 500-4000 mL/mL, and hydroisomerized on 0.1-1% platinum catalyst on mesoporous support with concentration of strong acid of 0.04-0.18 eq/g, concentration of medium strong acid of 0.06-0.2 eq/g and concentration of weak acid of 0.1-0.3 eq/g at 300-370 degrees C and 15-50 atm, and volume velocity of reaction mixture of 0.1-1.5 hour-1 and volume ratio of hydrogen to liquid mixture of 500-2500 mL/mL, to obtain a mixture of n-isoalkane. A fraction of mixture of n-isoalkane is separated by rectification with the boiling point interval of 145-275 degrees C, to obtain aviation biofuel.