A stirrer having a motor; a hollow shaft that is drivable via the motor and is provided with at least one additive outlet opening, via which an additive passed through the hollow shaft can be discharged; and a rotor arranged on the hollow shaft and having rotor blades, characterized in that a second rotor having rotor blades is provided on the hollow shaft at a distance from the first rotor, and in that the at least one additive outlet opening is provided between the two rotors, wherein the rotors are designed and drivable such that, during operation, a negative pressure and a centrifugal force are generated in the intermediate space defined between the rotors.

A wastewater purification apparatus includes an elongate tank, which has an inflow for feeding wastewater, a first vertical agitator with a first hyperboloid agitator body mounted on a vertical first agitator shaft and provided in a first treatment portion downstream of the inflow on the first narrow side, a second vertical agitator with a second hyperboloid agitator body mounted on a vertical second agitator shaft and provided in a second treatment portion downstream of the first vertical agitator, an aeration device with a fan for aerating wastewater received in the tank, a first drive device for rotating the first hyperboloid agitator body in a first rotation direction, a second drive device for rotating the second hyperboloid agitator body in a second rotation direction opposite the first rotation direction, and a decanter for discharging purified wastewater in a third treatment portion on a second narrow side opposite the first narrow side.

A hyperboloid agitator for circulating liquids, in particular water, wastewater or the like, in the centre of which a connection portion (2) for connection to a hollow agitator shaft (1) is provided, characterised in that the hyperboloid agitator is formed as a hollow body, with a central aperture (3) for supplying air being provided in the connection portion (2), and in that an air distribution device (9, 10, 11) for distributing air supplied through the aperture (3) to a plurality of air outlet openings (14) provided in the hollow body is provided downstream of the aperture (3)

An apparatus for producing nano-bubbles in a volume of liquid is described. The apparatus includes a motor having a rotatable shaft, an axially rotatable permeable member couplable to a gas inlet, and a rotatable tube support coupled to the rotatable shaft of the motor and having an inner cavity that houses the axially rotatable permeable member. When rotated, the axially rotatable permeable member is rotated so that the surface velocity of the rotatable permeable member simulates axial turbulent flow above the turbulent threshold in the liquid that allows the liquid to shear gas from the outer surface of the axially rotatable permeable member, thereby forming nano-bubbles in the liquid.

A hyperboloid agitator for circulating liquids, in particular water, wastewater or the like, in the centre of which a connection portion (2) for connection to a hollow agitator shaft (1) is provided, characterised in that the hyperboloid agitator is formed as a hollow body, with a central aperture (3) for supplying air being provided in the connection portion (2), and in that an air distribution device (9, 10, 11) for distributing air supplied through the aperture (3) to a plurality of air outlet openings (14) provided in the hollow body is provided downstream of the aperture (3).

A fluid gasification, pumping and mixing equipment, for fluids contained in open or closed bodies, which allows to control the bubble size and the proportion of mixed gases, of a gas flow to be diffused into the fluid, with means to generate a gas suction flow that allows active filling of cavitation zones created by the radial movement of a cavitation propeller, which can be used to suction at different depths without losing suction force or generate higher energy consumption.

A device for generating gas bubbles in a liquid in a container includes a rotatable gas-permeable hollow shaft arranged in a container, gassing discs arranged on the hollow shaft and spacers arranged between the gassing discs, gassing discs and spacers being arranged alternately on the hollow shaft in gas-tight contact with one another, a feed line for a compressed gas into the interior of the shaft, spacer having a centered opening (O) for receiving the shaft and at least two chambers, the chambers being equally spaced around the centered opening, where the centered opening and the chambers at least partially overlap, where the centered opening and the chambers are in communication with one another at least in the overlap region, so that the compressed gas can flow from the shaft into in each case a chamber of the spacer and enter the gassing discs from the chamber of the spacer.

An apparatus for aerating bodies of water, comprising a floating platform (19), a motor (15) supported by the floating platform (19), a transmission (16) which is coupled to the motor (15) and whose output shaft is in the form of a hollow shaft (17), a fan for supplying air through an air supply line (18) connected thereto, wherein the air supply line (18) is connected to one end (E1) of the hollow shaft (17), a hollow stirring shaft (1) coupled to the other end (E2) of the hollow shaft (17), an stirrer (K) affixed to the free end of the approximately vertical stirring shaft (1), wherein the stirrer (K) is designated as a hollow body and has a central opening (3) through which air supplied by the stirring shaft (1) can pass, and a multiplicity of air outlet openings (14).

Provided is an ultrafine bubble generation device for aquaculture or wastewater treatment with which it is possible to efficiently cause ultrafine bubbles to be dissolved or to coexist, and to increase the concentration of a gas in the liquid. An ultrafine bubble generation device for aquaculture or wastewater treatment provided with a channel for channeling a liquid, a compression device for pumping a gas into the channel, and a bubble generation medium for releasing the gas pumped by the compression device as ultrafine bubbles into the liquid in the channel, wherein the bubble generation medium is formed from a carbon-based porous material and is disposed so as to be horizontal or below horizontal with respect to the direction of flow of the liquid in the channel.

A device for generating gas bubbles in a liquid in a container includes a rotatable gas-permeable hollow shaft arranged in a container, gassing discs arranged on the hollow shaft and spacers arranged between the gassing discs, gassing discs and spacers being arranged alternately on the hollow shaft in gas-tight contact with one another, a feed line for a compressed gas into the interior of the shaft, having a centered opening (O) for receiving said shaft and at least two chambers, said chambers being equally spaced around said centered opening, where said centered opening and said chambers at least partially overlap, where the centered opening and the chambers are in communication with one another at least in the overlap region, so that the compressed gas can flow from shaft into in each case a chamber of the spacer and enter the gassing discs from the chamber of the spacer.