NOVELTY - Closed track pool microalgae cultivating system comprises at least two culturing regions for culturing microalgae, at least one carbon-supplementing region for collecting carbon dioxide gas and at least one circulating track pool composed of oxygen-removing regions for decreasing oxygen concentration in the culture solution.    USE - The closed track pool microalgae cultivating system is useful for sewerage treatment, carbon dioxide collection, and reuse of waste heat.    ADVANTAGE - The device costs little investment, has easily enlargeable scale, good effect on supplementing carbon but little biodeterioration and can be used for sewerage treatment, carbon dioxide collection and reuse of waste heat. It has obvious economic benefit and excellent environment benefit.    DETAILED DESCRIPTION - Closed track pool microalgae cultivating system comprises at least two culturing regions for culturing microalgae, at least one carbon-supplementing region for collecting carbon dioxide gas and at least one circulating track pool composed of oxygen-removing regions for decreasing oxygen concentration in the culture solution, where edge of the track pool is trough-shaped water sealing tank, outside of which is lower than inside; a transparent sealing cover is arranged above the culturing regions and carbon-supplementing region in the track pool to form a communicating closed space of culturing region and carbon-supplementing region; one end of the culturing region is connected with the carbon-supplementing region while the other is connected with a oxygen-removing region; both the carbon-supplementing region and the oxygen-removing region are connected with the culturing region by the other end; a circulating agitating device is arranged between the carbon-supplementing region and the culturing region for pushing algae solution in the track pool to flow; bottom of the culturing region is arranged with a heat exchange pipeline for heating up or cooling it; a circulating air-exchanging pipeline is arranged in the closed space between top of the culturing region and the anti-mist cover and one end is communicating with the external air-exchanging apparatus through a sterilizing and filtering device; inside of the culturing region is arranged with at least one sampling pipeline, one end of which is extending out of the closed space; bottom of the carbon-supplementing region is arranged with a carbon dioxide aeration device for supplementing carbon dioxide to algae solution in the carbon-supplementing region; bottom of the carbon-supplementing region is arranged with lower clapboard among which upper clapboards are arranged; adjacent upper clapboards and lower clapboards are staggered and opened, such that algae solution flows the carbon-supplementing region in shape of a snake; a transparent sealing cover is arranged above the oxygen-removing region to form a closed space relative to the culturing region and carbon-supplementing region; inside of the closed space is arranged with a circulating air-exchanging pipeline, one end of which is communicating with an external air-exchanging apparatus through a sterilizing and filtering device; bottom of the oxygen-removing region is arranged with an oxygen-removing aeration pipe for supplementing clean air to the algae solution in the oxygen-removing region and decreasing oxygen concentration in the algae solution; and two ends of the oxygen-removing region are connected with the culturing region through downtank.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the closed track pool microalgae cultivating system.