Abstract: In order to dissolve a gas such as oxygen in a liquid, typically aqueous, a stream of liquid is taken from tank 2 by a pump 10 and pressurized thereby. Oxygen is introduced into the stream via a conduit 18 upstream of a venturi 20. The resulting mixture of oxygen bubbles and liquid is accelerated from a sub-sonic to a super-sonic velocity as it flows through the venturi 20. The resultant shockwave is effective to reduce the size of the bubbles. The stream of liquid carrying oxygen bubbles dispersed therein is then transported at sub-sonic velocity along the conduit 12 to a sparge pipe 14 through which it is introduced into the main volume 4 of liquid into the tank 2. As the liquid passes through the orifices of the sparge pipe 14 so it is again accelerated to a super-sonic velocity and another shockwave is created thereby causing the bubbles to reduce in size such that they readily dissolve in or are consumed by the main volume of liquid.

Abstract: Sewage is oxygenated and clarified in a tank having an open-bottomed stilling chamber located above an open-topped chamber. Oxygenated sewage is discharged into the stilling chamber where its velocity is reduced, with sewage passing from the stilling chamber into the open-topped chamber being precluded from flowing horizontally along the tank bottom, and upwardly into the clarified sewage.

Abstract: The invention relates to apparatus for the treatment of sewage or other aqueous waste material having a biochemical oxygen demand in a single tank, the treatment involving the oxygenation of the sewage.With reference to FIG. 1, a volume of sewage in a treatment tank 110 establishes itself naturally into an upper layer 124 of clear liquid and a lower layer of liquid containing bacterial sludge. Liquid containing bacterial sludge from the lower layer 122 is united with incoming sewage from pipeline 120 and the resulting mixture is pumped by pump 114 into an oxygenating chamber 115 in which oxygen is dissolved in the liquid. The resulting oxygenated liquid enters a stilling chamber 112 located in the upper layer 124. Clear liquid is run off from the tank 110 over a weir 128.

Abstract: An apparatus and method for treating aqueous waste material having a biochemical oxygen demand comprises a method utilizing a vessel in which a volume of waste material establishes itself into an upper zone of clarified waste material and a lower zone of liquid containing bacterial sludge. Liquid from the lower zone is mixed with incoming sewage and the resulting mixture is fed first to an oxygenation chamber and then to a stilling chamber located in the upper zone of the vessel. Baffle means is located within the vessel for deflecting and reducing the momentum of the aqueous waste material as it leaves the stilling box and falls to the lower zone.

Abstract: An apparatus for removing gas from a liquid such as sewage comprises a siphon having a rising leg 2 arranged coaxially within a falling leg 3. Depending into the siphon from a closure member 4 is a skirt 5. A gas extraction pump 6 is in communication with the siphon by means of a tube 7 which extends through closure member 4 at a location outside the skirt 5. Any foam drawn through with gas in the liquid when the pump 6 is operated will have to pass through liquid since the vacuum is drawn from the pump 6 at a location outside the skirt 5.

Abstract: Oxygen containing gas is dissolved in sewage passing to, or through, a sewer during periods when sewage is being pumped therethrough. A stream of the sewage is withdrawn during periods when sewage is being held in the sewer. This stream is passed through a conduit so as to promote in such a stream dissolution of oxygen-containing gas introduced into, or entrained in, the stream. The stream is then returned to the sewer. By this means a chosen concentration of dissolved oxygen may be maintained in the volume of sewage between the points of withdrawal and return of the stream.

Abstract: A method for treating a body of liquid with a gas, which method comprises passing a stream of the liquid through a conduit, injecting gas intermittently into the stream at high pressure so as to dissolve at least some of the gas in the liquid stream, and introducing the stream containing dissolved gas and undissolved bubbles of gas into the main body of liquid under turbulent conditions such that the undissolved bubbles are shattered into even finer bubbles which dissolve in, or are consumed within, the main body of liquid.

Abstract: A process for treating aqueous waste material having a biochemical oxygen demand, which process comprises passing the aqueous waste material along an elongate treatment tank or other elongate container for containing a volume of such material, having a transverse support structure or structures extending along the length of the tank or container and supporting aerobic micro-organisms, and dissolving an oxygenating gas in aqueous waste material at a plurality of positions spaced along the tank.

Abstract: Apparatus and method for dissolving gas in a body of liquid comprising a gas/liquid contactor device having a plurality of discrete conduit sections of different cross-sectional area connected in series or in parallel.A stream of liquid is passed through the device and gas is introduced into the stream upstream of the device to establish a turbulent gas/liquid contact zone in at least one of the conduit sections.The liquid stream with gas dissolved in it is introduced into the main body of liquid.

Abstract: Process for treating liquid. The liquid is contained in a vessel. A stream of liquid is passed under pressure through a line. Gas is introduced into the stream and downstream of the gas introduction point the stream passes downwardly through an expansion chamber in which its velocity is reduced in order to allow a prolonged gas/liquid contact. The pH of the liquid in the vessel is controlled to a value in a predetermined range.