The invention relates to a stirred tank reactor for gas-liquid mass transfer in a slurry. The reactor includes a reactor tank (1) having a first volume (V.sub.1), a drive shaft (2) that extends vertically in the reactor tank, a motor (3) for rotating the drive shaft (2), a main impeller (4) which is a downward pumping axial flow impeller attached to the drive shaft (2) to create a main flow pattern in the reactor tank, and a gas inlet (5) arranged to supply gas into the reactor tank (1) to be dispersed to the liquid. The reactor includes a mechanical gas sparging apparatus (6) comprising a dispersion chamber (7) having a second volume (V.sub.2) which is substantially smaller than the first volume (V.sub.1) of the reactor tank (1), the dispersion chamber being arranged coaxial with the drive shaft (2), and the gas inlet (5) being arranged to feed gas into the dispersion chamber (7), and mixing means (8, 9, 10, 11, 12) arranged within the dispersion chamber (7) for mixing the gas into liquid by dispersing the gas to fine bubbles before the bubbles enter the main flow pattern. The mixing power per unit volume inside the dispersion chamber (7) is significantly larger than the mixing power elsewhere in the reactor.

An apparatus for treating fluids such as waste streams with improved aeration efficiency and dual function operation has a blower-assisted aerator, an impeller, a baffle structure circumscribing an air line that includes a first baffle and a second perforated baffle downstream from the first baffle, and a liquid reservoir containing a liquid. The impeller is fully submerged, and located upstream of the fully submerged baffle structure. A fully submerged air outlet is located downstream of the baffle structure, preferably in close proximity to the perforated baffle. When the blower is stopped and the impeller rotating, the baffle structure prevents aspiration into the liquid. In some embodiments, the baffle structure is removably affixed to an air outlet from the blower-assisted aerator, and so may be applied to pre-existing blower-assisted aerators. In some embodiments, one or both of the first and second baffles may resemble flat, domed, cupped, or hemispherical washers.

A rotary gas bubble ejector has a fluid reservoir chamber having at a bottom end a fluid discharge opening and a shaft extending through fluid reservoir chamber in connection with a rotor plate. The rotor plate has an outer dimension greater than the outer dimension of fluid discharge opening and is positioned proximate bottom end of fluid reservoir chamber such that a fluid acceleration gap is formed. Rotation of the shaft and rotor plate initiates a fluid flow thereby generating a low-pressure zone within the fluid acceleration gap, wherein gas is discharged from the fluid reservoir chamber into the fluid acceleration gap. As the gas is expelled from the fluid acceleration gap, fluids, gas and liquid, are brought into contact producing micro-sized gas bubbles that are ejected into the body of liquid.

In an apparatus for mass transfer between a liquid and a gas inside a rotor, the liquid is supplied to a center of the rotor and is driven outward by centrifugal force generated by rotation of the rotor, the gas surrounding the rotor is forced inward through the rotor by a pressure of the gas, counter to the liquid flow in the rotor, and the rotor has a plurality of passages lying in the plane of the rotor that begin at a center of the rotor and terminate at an outer circumference of the rotor. The passages are each filled with a packing that increases the area of contact between the liquid and the gas.

A device and method for injection of oxygen-rich gas into a body of liquid with oxygen recycling are disclosed. The device comprises a rotary hollow shaft vertically passing through a float partially immersed in the liquid, an impeller attached to the lower end of the rotary hollow shaft, a columnar structure, surrounding the rotary hollow shaft, mounted on the bottom side of the float and vertically extending into the liquid, a gas diffusion chamber formed by the columnar structure, the float and the liquid surface under the float, and a gas injection conduit passing through the float for delivering the oxygen gas into the gas diffusion chamber, wherein a vacuum is generated in the body of the liquid around the impeller when the impeller is driven to rotate, so that the oxygen-rich gas in the gas diffusion chamber is sucked into the body of the liquid and mixed therein.

A submersible aeration apparatus includes an air passage formed on a pump chamber to draw air into the pump chamber. A suction port formed on a lower side of the pump chamber draws liquid into the pump chamber. An impeller draws air through the air passage and liquid through the suction port. An ejection passage ejects the air and liquid. The impeller includes a main plate portion to cover a connection port connecting the air passage to the pump chamber. A vane portion protrudes downward from a lower surface of the main plate portion on the suction port side. The main plate portion has a cut-out part connecting the air passage and the pump chamber, and a groove part recessed from an upper surface of the main plate portion toward the lower surface and extending from an inner peripheral side toward an outer peripheral side of the main plate portion.

A submersible aeration equipment (10) for wastewater treatment in which partial vacuum is generated by the rotation of the impellers (22) within the water, which results in the formation of micro-bubbles. The submersible aeration equipment (10) includes a spring-based air intake valve (18) that can control the flow of air through a hollow shaft (12), wherein the opening of the spring-based air intake valve (18) is based on the amount of vacuum in the hollow shaft (12).

A submersible aeration equipment (10) for wastewater treatment in which partial vacuum is generated by the rotation of the impellers (22) within the water, which results in the formation of micro-bubbles. The submersible aeration equipment (10) includes a spring-based air intake valve (18) that can control the flow of air through a hollow shaft (12), wherein the opening of the spring-based air intake valve (18) is based on the amount of vacuum in the hollow shaft (12).

A submersible aeration apparatus includes an air passage formed on a pump chamber to draw air into the pump chamber. A suction port formed on a lower side of the pump chamber draws liquid into the pump chamber. An impeller draws air through the air passage and liquid through the suction port. An ejection passage ejects the air and liquid. The impeller includes a main plate portion to cover a connection port connecting the air passage to the pump chamber. A vane portion protrudes downward from a lower surface of the main plate portion on the suction port side. The main plate portion has a cut-out part connecting the air passage and the pump chamber, and a groove part recessed from an upper surface of the main plate portion toward the lower surface and extending from an inner peripheral side toward an outer peripheral side of the main plate portion.

Aeration device for bioreactors with an aeration element with gas outlet openings arranged in a housing, the aeration element taking the form of a microsparger, the gas outlet openings of which are in each case spaced apart from one another and have a size of between 100 m and 200 m. At least one second aeration element with gas outlet openings of a second size is preferably provided, the aeration elements being formed by a common housing with separate aeration channels.