NOVELTY - The apparatus comprises a process water storage tank, a transition tank, an exchanger formed of a pasteurization section, a recuperation section and a cooling section, an ice water aggregate, a heating water tank, a photobioreactor, a reproduction and heating pure cultures tank, a prepared nutrients heating tank, a carbon dioxide gas tank, a mixing pump (11), a centrifuge, and a biomass storage tank. The photobioreactor includes a light element placed inside of the photobioreactor. The light element is formed of a cylindrical transparent tube having a ring-shaped, circular cross section.    USE - The apparatus is useful for cultivating phototrophic microorganisms such as microalgae (claimed).    ADVANTAGE - The apparatus economically and efficiently cultivates the phototrophic microorganisms in a continuous and hermetic manner, and can be maintained at a constant temperature optimal for the cultivation.    DETAILED DESCRIPTION - The apparatus comprises a process water storage tank, a transition tank, an exchanger formed of a pasteurization section, a recuperation section and a cooling section, an ice water aggregate, a heating water tank, a photobioreactor, a reproduction and heating pure cultures tank, a prepared nutrients heating tank, a carbon dioxide gas tank, a mixing pump (11), a centrifuge, and a biomass storage tank. The photobioreactor includes a light element placed inside of the photobioreactor. The light element is formed of a cylindrical transparent tube having a ring-shaped, circular cross section and a column with LEDs embedded on its walls. The column is placed inside the tube. The tube is sealed from a bottom with a lid, and top edges of the tube project above a closing cover of a photobioreactor tank (14). An upper outlet of the column is profiled, while the column is formed of a passthrough tube. The column includes a fan. Vertical collectors are located on the outer side of the transparent tube and parallel to its vertical axis, and are powered by a mixing pump. Hydraulic nozzles are mounted in the collectors. Outlets of the collectors face an outer surface of the tube. The LED emits blue light at a wavelength of 450-470 nm, orange light at a wavelength of 650-670 nm, and red light at a wavelength of 700-740 nm. An inner wall of the photobioreactor tank constitutes reflective surface for the emitted light. The walls of the photobioreactor tank constitute a heating jacket with an outer insulation layer (16). Mixing nozzles are mounted at a sidewall of the photobioreactor tank, and constitute outlets of conductors connected to a pump discharge connector. The photobioreactor tank includes a turbidity sensor (47).    DESCRIPTION OF DRAWING(S) - The figure shows a schematic longitudinal sectional view of a photobioreactor.    Mixing pump (11)    Photobioreactor tank (14)    Outer insulation layer (16)    LED (25)    Turbidity sensor. (47)