PURPOSE: To remove nitrogen in waste water and to carry out a stable treatment, by switching a stirring apparatus for aeration to plural steps such as high and low, or high, medium and low velocity, and generating an aerobic or anaerobic state alternately in an oxidation tank.
CONSTITUTION: The revolution velocity of a stirring apparatus (rotor) 2 for aeration provided in an oxidation ditch 1 is made variable, and the concentration of dissolved oxygen in the oxidation ditch 1 is detected by operating a dissolved oxygen densitometer 4 in congunction with the rotor 2. The rotor 2 is switched to plural steps such as high and low, and high, medium, and low velocity in accordance with the dissolved oxygen concentration and an aerobic or anaerobic state is generated alternately in an oxidation ditch 1 without completely stopping the rotor 2 to nitrify and to denitrify the nitrogen in the waste water such as untreated sewage. A part of the waste water drained continuously from the oxidation ditch 1 is stored in a precipitation basin 3, and the precipitate is sent back to the oxidation ditch 1 as returned sewage sludge.
ARAKI TOSHIHIDE
KAGA AKIRA
| JPS5719094A | 1982-02-01 | |||
| JPS5732790A | 1982-02-22 | |||
| JPS57162697A | 1982-10-06 | |||
| JPS5448958A | 1979-04-17 |