Biogas production system

A biogas production system configured to produce biogas using, as raw materials, waste water-soluble coolants collected from machining devices that perform machining, the biogas production system comprising:

• a plurality of storage tanks configured to separate by type and store the waste water-soluble coolants collected from the machining devices;
• concentration measuring units configured to measure concentrations of the waste water-soluble coolants in the storage tanks;
• a mixing device configured to prepare a coolant mixture containing a plurality of the waste water-soluble coolants by mixing the waste water-soluble coolants in the storage tanks at a ratio calculated based on the concentrations of the waste water-soluble coolants;
• a fermentation device configured to generate the biogas by fermenting the coolant mixture supplied from the mixing device using microorganisms;
• a dilution device configured to supply, to at least one type of liquid selected from the group consisting of the waste water-soluble coolant and the coolant mixture, a dilution liquid for diluting the liquid;
• and
• a second concentration measuring unit configured to measure a concentration of the coolant mixture, wherein the dilution device is configured to adjust a supply amount of the dilution liquid based on the concentration of the coolant mixture.