NOVELTY - A circulation conversion system comprises anaerobic fermentation system (1), carbon dioxide adsorption tank (2), diatomite (3), micro-pore gas distribution system (4), online monitoring and automatically controlling hazardous gas system (5), data collecting integrated system (6), 1st electromagnetic valve (7), 2nd electromagnetic valve (8), anoxic biological filter system (9), solar drying system (10), pyrolysis system (11), and gas storage system (12) in which anaerobic fermentation system and micro-pore gas distribution system are connected to diatomite and carbon dioxide micro-pore system.    USE - A circulation conversion system for carbon dioxide gas (claimed).    ADVANTAGE - System is capable of realizing resource utilization of biogas and environment-friendly, can reuse diatom as biomass, and reduces pH of water to promote diatom growth.    DETAILED DESCRIPTION - A circulation conversion system comprises anaerobic fermentation system (1), carbon dioxide adsorption tank (2), diatomite (3), micro-pore gas distribution system (4), online monitoring and automatically controlling hazardous gas system (5), data collecting integrated system (6), 1st electromagnetic valve (7), 2nd electromagnetic valve (8), anoxic biological filter system (9), solar drying system (10), pyrolysis system (11), and gas storage system (12) in which anaerobic fermentation system and micro-pore gas distribution system are connected to diatomite and carbon dioxide micro-pore system in carbon dioxide adsorption tank, outlet end of carbon dioxide absorbing tank is connected with online monitoring and automatically controlling hazardous gas system, solar drying system, inlet end of carbon dioxide adsorption tank via 1st electromagnetic valve and gas on-line monitor system, online monitoring and automatically controlling hazardous gas system through 2nd electromagnetic valve are connected to micro-aerobic biological filtering system, and gas storage system, solar drying system is connected with pyrolysis system and gas storage system, data collecting control integrated system, 1st electromagnetic valve, 2nd electromagnetic valve, and gas on-line monitoring system.    DESCRIPTION OF DRAWING(S) - The drawing shows a structure frame of circulation conversion system.    Anaerobic fermentation system (1)    Carbon dioxide adsorption tank (2)    Diatomite (3)    Micro-pore gas distribution system (4)    Online monitoring and automatically controlling hazardous gas system (5)    Data collecting integrated system (6)    First electromagnetic valve (7)    Second electromagnetic valve (8)    Anoxic biological filter system (9)    Solar drying system (10)    Pyrolysis system (11)    Gas storage system (12)