Abstract: An improved, multipass, horizontal rotating continuous feed digester provides an efficient aerobic digestion process for sewage, and which also reduces pollution. The improved digester promotes the ecology in that the gas and air feed and exhaust means are located at opposite ends of the digester. Moreover, the air and gas distribution means can be easily removed from the digester for inspection and cleaning.

Abstract: A centrifugal pump having a rotatable impeller that operates to drain liquid into the intake of the pump. An air-introduction passage connects with a subatmospheric pressure region at the back of the impeller. Air introduced through this passage is mixed with a portion of the fluid pumped, and the air-fluid mixture is expelled as the discharge of the pump.

Abstract: A centrifugal pump having a rotatable impeller that operates to drain liquid into the intake of the pump. An air-introduction passage connects with a subatmospheric pressure region at the back of the impeller. Air introduced through this passage is mixed with a portion of the fluid pumped, and the air-fluid mixture is expelled as the discharge of the pump.

Abstract: An apparatus and method for increasing gas absorption in a liquid includes, in a first embodiment, gas injection airfoils at an inlet of an extended vertical tube and a pump at an outlet of the tube for drawing the liquid at a rate greater than the rise rate of the gas bubbles. An outlet of the pump preferrably includes a plurality of outlet nozzles. A second embodiment for use with a liquid or slurry includes a venturi gas inlet in place of the airfoils.

Abstract: An apparatus and method for increasing gas absorptiion in a liquid includes, in a first embodiment, gas injection airfoils at an inlet of an extended vertical tube and a pump at an outlet of the tube for drawing the liquid at a rate greater than the rise rate of the gas bubbles. An outlet of the pump preferrably includes a plurality of outlet nozzles. A second embodiment for use with a liquid or slurry includes a venturi gas inlet in place of the airfoils.

Abstract: In order to inject oxygen into a liquid, for example, sewage, the installation is provided with an aerating system (2) that is arranged in an aerating basin (1).In order to improve the oxygen injection rate per kilowatt of driving force the aerating system (2) that is connected with a pump (3) in the manner of a water jet pump, the flow cross-section of which, in its air intake area, can be varied so as to change the oxygen injection rate. To this end, the diffusor stage (8) of the aeration system (2) extends along a conical surface. The hollow-configured conical diffusor inner portion (13) is arranged, together with a surface aeration impellor (16), on a common drive shaft (14), and can be moved along its longitudinal axis (15).

Abstract: A rotating gas diffuser for shearing fine gas bubbles from the surface thereof when the diffuser is immersed in a body of liquid and rotated therein. The rotatable shaft of the diffuser carries a disk like member defining at least one gas plenum having a porous wall out of which gas introduced into the plenum can pass to form nascent gas bubbles which are then sheared off by the viscous shear forces exerted by the liquid in which the disk is rotating. Preferably both the top wall and the bottom wall forming the gas plenum or plenums are porous. The ratio of the overall diameter of the disk to the maximum thickness of the disk in the gas diffusing area occupied by the plenums is at least about 32:1. Improved results are obtained when this ratio is at least about 48:1, more improvement is obtained with a ratio of at least about 64:1, and still greater improvement with a ratio of at least about 128:1. The preferred value of the ratio is at least about 256:1.

Abstract: A rotating gas diffuser for shearing fine gas bubbles from the surface thereof when the diffuser is immersed in a body of liquid and rotated therein. The rotatable shaft of the diffuser may carry a plurality of main rigid structural spokes and an equal number of rigid hollow gas feed conduits positioned alternately around the shaft. A plurality of plates, each in the form of a section of an annulus with its lateral edges radially positioned with respect to the circular rotating gas diffuser, is supported either on the top or the bottom of the diffuser, or on both, near its perimeter. Each porous plate is carried by a plate holder that has a shape similar to its associated porous plates, and with those plates defines a gas plenum having an area substantially equal in extent to, but no greater than, the area of the plates.

Abstract: A device for revolving a liquid has a hollow shaft for supplying gas to the liquid, and the free end of the shaft is immersed in the liquid where it carries a propeller for revolving the liquid. The propeller comprises at least one screw-shaped vane, and at least part of the vane's surface forms an acute angle with the longitudinal axis of the hollow shaft, as seen from the free end of the shaft, the vane extending along at least two thirds of the circumference of the shaft.