Activated sludge process
AssigneeSeisuikogyo Co., Ltd.
InventorsTsuneo Hasegawa, Seitaro Hasegawa
Life of this patent
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Abstract
In the activated sludge process for treating waste water containing a spongy substance in a flowing state by subjecting it to aeration in an aeration tank, an improved process comprising taking out a portion of said spongy substance from the aeration tank continuously in order to remove a part of the sludge adhering to the spongy substance and then returning the thus reclaimed spongy substance into the aeration tank for reuse.
Claims7
An activated sludge process for treating waste water, said process employing an aeration tank having at its upper end a narrowed discharge conduit of smaller transverse cross-sectional area than the transverse cross-sectional area of the main body of said aeration tank, which comprises the steps of:
- feeding waste water into said aeration tank and flowing an oxygen-containing gas upwardly through said waste water in said aeration tank and thence through said discharge conduit thereby aerating and agitating said waste water in the presence of a multitude of small spongy pieces, said spongy pieces being in a free flowing state suspended in the waste water in said aeration tank and having activated sludge adhering to the surfaces thereof, said spongy pieces retaining said activated sludge thereon in a condition effective to cause said waste water to be purified by said activated sludge under aerated conditions, the flow of said gas into said discharge conduit generating an air lift effect for moving waste water and spongy pieces from the top of said aeration tank upwardly into said discharge conduit;
- intermittently or continuously discharging from said aeration tank a portion of the contents of said aeration tank comprising a mixture of said spongy pieces and treated waste water, said portion being discharged through said discharge conduit by the air lift effect;
- feeding the spongy pieces discharged from said aeration tank into a head tank having pressing rolls located therein and containing the waste water that is to be fed into said aeration tank, and pressing the spngy pieces thereby removing a part of the sludge that is adhered thereto and is present in the interior thereof and then discontinuing the pressing whereby to restore the spongy pieces to a state in which they are capable of supporting treatment of waste water under aerated activated sludge conditions without proliferation of anaerobic bacteria in the interiors thereof;
- and then returning the thus-treated spongy pieces into said aeration tank.
Dependencies are inferred from the claim text.