TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: The method further involves concentrating the cells from the cell culture solution. The cell culture solution is fermented for increasing amount of fat-soluble substances and solvent extraction is performed for facilitating dissolution of the fat-soluble substances. The method involves repeating the dissolution, extraction and concentration step for one or more times, and recovering solvent from the solution to obtain desired concentration of cells and fat-soluble substances. The cells are fermented using organic wastewater including low molecular weight organic acid, as a source of nutrients to cell culture solution. The cells are cultured in culture solution containing diluted organic wastewater having total chemical oxygen demand (TCOD) of 100-10000 mg/l and nitrogen concentration of 100-800 mg/l. The method involves recovering cell secreted substances and/or other pathogens capable of inhibiting growth of the cells from the cell culture solution. The cells are separated from the cell culture solution and concentrated by subjecting the culture solution to sedimentation or by applying ultrasonic resonance. The method involves stirring and agitating mixed solution during fermentation for increasing contact between the solvent and cell culture solution and concentration of fat-soluble substances inside the cell. The method involves separating fatty acid and other pigments from the fractionated fat-soluble substances. The method involves adding carbon source to the culture solution in addition to other nutrient sources for inducing production of fat-soluble substances. The concentration of dissolved oxygen is controlled in the cell culture solution during fermentation process. The cells are cultured after separation once or twice and cells are concentrated further after re-fractionated for 1 or 2 times. Preferred Components: The organic wastewater is purified for removing contaminants or pollutants present in the water and then the cells are cultured in the culture solution containing purified organic wastewater. The solvent is hydrocarbon solvent. The nutrient sources are nitrogen, carbon, phosphorus, vitamin, microelements, macroelements, or silica, or their mixtures. Preferred Apparatus: The separation device has ultrasonic resonance generator and sedimentation device. The apparatus has cell circulation pipe (80) for circulating separated cells from the separation device to culture device, solvent circulation pipe (90) for circulating the fractionated fat-soluble substances-solvent from the fractionating device to the solvent device. The mixing device is stirrer. The apparatus has first pump (2) and third pump (4) for transferring fixed amount of the separated cells from the separation device. The apparatus further has vibration milling device (31) for grinding cell culture solution and stirrer (32) for agitating mixture. The apparatus has fermentation device for producing biogas, organic wastewater storing unit, unit for cell maturation, biogas storing unit and cell concentration device and water storing unit. The unit for cell maturation, stirring device and separation device are integrated into one integrated device. The integrated separation unit has pump installed between lower pipe connected to inlet tube, pipe for returning back the collected fat-soluble substances-solvent to the solvent device and stirrer for mixing cell culture solution and fat-soluble substances. The cell concentration device, unit for cell maturation, mixing device and separation device are integrated into one integrated device. EXAMPLE - No suitable example given.