| 摘要 |
<p>PURPOSE:To uniformize the thickness of a biological membrane by providing a plurality of units of agitation mechanisms different in shape in the vertical direction of the inside of a biological reaction tank and rotating these agitation mechanisms at different revolutions. CONSTITUTION:Waste water stays in an aeration tank 35 and overflow discharged therefrom is introduced through a duct 37 into a biological reaction tank 11 from a supply port 38 of waste water. The waste water introduced into the biological reaction tank 11 descends between the inner wall of the reaction tank 11 and the outer wall of a rectification column 13 and reaches the packed part of carriers 42. The waste water reaching the packed part flows to a precipitation tank 31 from an aperture part 11a and goes out through a duct 41 via a gutter 32. The other water overflowed from the aperture part of the upper end of the rectification column 13 descends between the inner wall of the biological reaction tank 11 and the outer wall of the rectification column 13 and circulates in the biological reaction tank 11. Furthermore the waste water staying in the aeration tank 35 is aerated by air introduced through a vent hole 33a. Thereby the solubilization efficiency of oxygen is enhanced.</p> |
