| abstract |
A method for automatically controlling the level of dissolved oxygen in water, including the stops of mixing air or oxygen and nitrogen gas so as to be dissolved in retained water in a closed tank. The retained water is circulated by a pressure pump, activated by a ceramic pipe and an infrared ray irradiation device and then injected into the water in the closed tank. The mixing ratio of the air or oxygen and nitrogen gas mixed with to retained water is adjusted, the pressure in the pressure tank is changed, and the injecting pressure of the gas injection nozzle is changed. Sludge or the like is removed from the water by filtering, the oxidation-reduction potential of the water is adjusted to a desired level, and the water is sterilized by an ultraviolet ray irradiation device and brought back to the closed tank. |