Abstract Combined apparatus for the biological purification of waste waters by means of activated sludges, which comprises at least two coupled clarification tanks which are in communication with an aerator tank as well as means for recycling the settled sludges coming from the clarification tanks into the aerator tank, characterized by the fact that the means for recycling the settled sludges consist of air pumps of the ''''air-lift'''' type which discharge into the aerator from each of the clarifiers and which are fed with air with a pulsating intermittent flow, alternating in each of the clarifiers, which causes a pulsating recirculation of the settled sludges, alternately from each of the clarifiers towards the aerator. The air-lifts are so developed that they have a base which is flared with respect to their top, said base constituting the orifice thereof for the drawing in of settled sludges which are to be recycled.
In combined apparatus for the biological purification of waste waters by means of activated sludges having at least two clarifying tanks coupled with an aeration tank, a plurality of first connecting means for transferring sedimented sludge from each of said clarifying tanks to said aeration tank, and a plurality of second connecting means for transferring treated waste water mixed with sludge from said aeration tank to said clarifying tanks, the improvement wherein said first connecting means comprises air lift pumps, there being at least two of said pumps for each clarifying tank, and means for feeding air to said pumps in a pulsating intermittent flow, said flow alternating with respect to each of said clarifying tanks, whereby a pulsating recirculation of the settled sludge alternately from each of said clarifying tanks towards said aeration tank is caused, each of said pumps having a flared base located at the bottom of the clarifying tank and a narrow upper portion connecting to the aeration tank, the flared bases of the pumps in each of the clarifying tanks being located closely adjacent tO one another to provide a substantially uninterrupted inlet port providing continuous communication between the bottom of each clarifying tank and the upper portion of the aeration tank.
Claim 2
Dependent Claim
207 words
In combined apparatus for the biological purification of waste waters by means of activated sludges having at least two clarifying tanks coupled with an aeration tank, a plurality of first connecting means for transferring sedimented sludge from each of said clarifying tanks to said aeration tank, and a plurality of second connecting means for transferring treated waste water mixed with sludge from said aeration tank to said clarifying tanks, the improvement wherein said first connecting means comprises air lift pumps, there being at least two of said pumps for each clarifying tank, and means for feeding air to said pumps in a pulsating intermittent flow, said flow alternating with respect to each of said clarifying tanks, whereby a pulsating recirculation of the settled sludge alternately from each of said clarifying tanks towards said aeration tank is caused, each of said pumps having a flared base located at the bottom of the clarifying tank and a narrow upper portion connecting to the aeration tank, the flared bases of the pumps in each of the clarifying tanks being located closely adjacent tO one another to provide a substantially uninterrupted inlet port providing continuous communication between the bottom of each clarifying tank and the upper portion of the aeration tank.