Patent Description:
This disclosure relates to a submersible aeration device and methods for producing nano-bubbles in a liquid volume.

Various systems, such as pump or blower systems, have been used to supply gas to a volume of a liquid medium to obtain a desired gas saturation level in the liquid medium. Gas saturation is the ratio of the concentration of gas dissolved in the liquid medium to the maximum concentration of gas that can be dissolved in the liquid medium under stable equilibrium. An aeration system can recirculate liquid (e.g., water) using one or more pumps to dissolve gas into the liquid.

As an example, the amount of dissolved oxygen in a source of water can indicate its water quality. Various living organisms utilize the oxygen present in sources of water. In some cases, it is desirable to maintain a level of oxygen saturation in a liquid. In some cases, it is desirable to increase the amount of dissolved oxygen in water.

<CIT> describes an apparatus for producing bubbles with an axially rotatable permeable member and a rotatable tube support which houses the axially rotatable permeable member. <CIT> describes an apparatus and method for introducing various gasses into liquids. One disadvantage of the current systems is that many are not feasible or applicable under certain circumstances. For example, the aeration system may not be efficient for a large body of water (or other liquid mediums). Also, pumping to recirculate a large body of water may not be feasible due to inefficiencies or a lack of equipment accessibility. Consequently, there is a need for an alternative means for obtaining an increased oxygen saturation level in such conditions.

As used herein, the term "nano-bubble" refers to a bubble that has a diameter of less than one micrometer (µm). A microbubble, which is larger than a nano-bubble, is a bubble that has a diameter greater than or equal to one µm and smaller than <NUM>. A macro-bubble is a bubble that has a diameter greater than or equal to <NUM>.

Described herein is an apparatus for producing nano-bubbles in a volume of a non-aerated liquid (e.g., water). The apparatus includes a motor and an axially rotatable permeable member. The motor includes a rotatable shaft. The axially rotatable permeable member includes a body having a wall and a plurality of pores through which gas introduced into the axially rotatable permeable member can flow, the axially rotatable permeable member further including at least one radially-extending member, the axially rotatable permeable member couplable to a gas inlet configured to introduce gas from a gas source into the axially rotatable permeable member, the axially rotatable permeable member coupled to the rotatable shaft of the motor and adapted to rotate along with the rotatable shaft.

When rotated, the axially rotatable permeable member simulates turbulent flow above the turbulent velocity threshold (e.g., <NUM>/s or higher) in the liquid such that the liquid shears gas from the outer surface of the rotatable permeable member to form nano-bubbles. This "simulated" turbulent flow of the surrounding liquid at a level above the turbulent threshold can promote the formation of nano-bubbles by shearing gas from the surface of the rotatable permeable member to form the nano-bubbles and preventing them from coalescing.

This, and other aspects, can include one or more of the following features.

The rotatable permeable member can have an outer circumference defined by an outer diameter sized to simulate turbulent flow above the turbulent threshold of the liquid.

The pores of the rotatable permeable member can have a diameter in a range of from <NUM> nanometers (nm) to <NUM>, or a diameter that is less than or equal to <NUM>.

The apparatus can further include a rotatable tube support including an elongate body having a wall and defining an inner cavity, the wall defining a plurality of perforations, the inner cavity of the rotatable tube support configured to house the axially rotatable permeable member, the rotatable tube support coupled to and rotatable along with the rotatable shaft of the motor.

The perforations of the rotatable tube support can be circular, semi-circular, rectangular, cubical, oblong, triangular, or slotted.

The nano-bubbles can have a mean diameter less than <NUM>, less than <NUM>, ranging from about <NUM> to about <NUM>, or ranging from about <NUM> to about <NUM>.

The rotatable permeable member further comprising at least one radially-extending member. The radially-extending member can include at least one wing, vane, propeller, or combinations thereof. The rotatable permeable member, when rotated with the at least one radially-extending member, is adapted to move the liquid away from an outer surface of the body of the rotatable permeable member and simulate turbulent flow above the turbulent threshold in the liquid that allows the liquid to shear gas from the outer surface of the rotatable permeable member, thereby forming nano-bubbles in the liquid.

Also described is a method for producing nano-bubbles in a volume of liquid using the above-described apparatus. At least a portion of the apparatus is submerged in a liquid. A gas is introduced from a gas source into the rotatable permeable member through the gas inlet at a gas pressure that forces the gas through the pores of the rotatable permeable member. Rotating the rotatable permeable member and tube support simulates turbulent flow above the turbulent velocity threshold in the liquid such that the liquid shears gas from the outer surface of the rotatable permeable member to form nano-bubbles.

The pressure of the gas flowing into the permeable member can range from about <NUM>,<NUM> kPa to about <NUM>,<NUM> kPa (about <NUM> atmosphere (atm) to about <NUM> atm).

The above-described apparatus and method can be used in a number of applications, including water treatment.

The above-described apparatus and method offer a number of advantages. For example, the generation of nano-bubbles can allow for more efficient diffusion and/or dissolution of gas in the surrounding liquid in comparison to the generation of bubbles of larger size. This higher transfer efficiency of nano-bubbles can be especially useful in applications where aeration is desired for a large body of liquid where it may not be feasible or practical to use traditional or current state of the art of aeration, such as pumping, to provide recirculation of the large body of liquid. Some non-limiting examples of such large bodies of liquid include a lake, a pond, a canal, and an ocean.

Rotation of the rotatable permeable member can be implemented by a driving mechanism that is submerged, partially submerged, or above the surface of the liquid in which aeration is desired. The rotatable permeable member and the tube support may be simultaneously rotated together. The gas flowed into the rotatable permeable member can be a low pressure gas (for example, a gas with a pressure equal to or less than <NUM> atmospheres), for example, from a blower or air pump. In some implementations, the device (including the rotatable permeable member and the driving mechanism) can be completely submerged in the liquid in which aeration is desired. In some implementations, the device can be used to generate nano-bubbles in a liquid without requiring the need to further pump (that is, induce flow in) the liquid in which aeration is desired. The device can be compact in size (for example, as small as <NUM> (<NUM> inches) in diameter), such that the device can be placed within a confined space, such as a manhole. The device can be integrated with any rotating equipment that can provide sufficient rotation speed to the rotatable permeable member to generate nano-bubbles.

The apparatus provided herein advantageously simulates the flow condition necessary for producing nano-bubbles in a liquid under any flow condition (e.g., no flow, laminar flow or turbulent flow conditions). Exposure to actual turbulent flow or generating actual turbulent flow is therefore not required for nano-bubble production. Rotation of the rotatable permeable member simulates turbulent flow above the turbulent velocity threshold in the liquid such that the liquid shears gas from the outer surface of the rotatable permeable member to form nano-bubbles. Thus, the apparatus provides the benefit of producing nano-bubbles independent of the liquid flow condition.

The details of one or more implementations of the subject matter of this disclosure are set forth in the accompanying drawings and the description.

This disclosure describes a submersible aeration device for producing nano-bubbles in a given volume of a liquid carrier (e.g., a body of water). A gas, such as oxygen, nitrogen, or air, can be flowed through the pores of a rotatable permeable member, where the liquid shears the gas under turbulent flow conditions above the turbulent threshold of the liquid created by rotation of the rotatable permeable member to generate nano-bubbles, which can aerate the liquid. The nano-bubbles have diameters less than one micrometer (µm). In some implementations, the nano-bubbles have diameters less than or equal to <NUM> nanometers (nm).

The aeration devices and methods can be implemented in a variety of settings. One example includes a tank that lacks fittings to couple to an additional aeration system. The aeration devices and methods described can also be implemented in a reactor and/or a tank installed at a wastewater treatment plant or other industrial facility; a manhole lift station or other pump station, in which the device can be lowered into a wet-well to transfer gas to a liquid; or the aeration devices and methods described can be implemented in a stormwater drain, a drainage ditch, or an irrigation ditch in which the liquid depth is low (for example, as little as <NUM> (<NUM> inches) of liquid depth).

The aeration devices and methods described can also be implemented in a body of water, e.g., at the bottom of a body of water, for example, at an underwater depth of a few hundred feet, in a lake or other aquatic environment for the purpose of algae control and/or to increase oxygen levels.

Other applications of the aeration devices and methods include concrete production, for example, to alter one or more properties of the concrete. The aeration devices and methods described can also be implemented in a swimming pool to reduce the use of chorine or other oxidizers, or in canal treatment, for example, by a homeowner at a personal dock to restore the natural level of oxygen to stagnant water.

The aeration devices and methods described can be implemented in aquaponics and/or aquarium tanks, or in ponds, for example, a decorative pond in which it may not be desirable that auxiliary equipment (such as the aeration device) be located outside the pond. The aeration devices and methods described can be implemented in a bait tank to keep fish with satisfactory levels of oxygen, so they live longer, or in ocean aquafarming, for example, for fish and/or crustaceans. Other applications include manmade ponds, reservoirs, and/or distribution systems for holding water, such as those used to store and convey oilfield produced water, reclaimed water, treated wastewater, and/or potable water for aeration, oxidation, and oil separation.

<FIG> show an example aeration device <NUM> not claimed as such. The device <NUM> includes a base <NUM>, a driving mechanism <NUM> coupled to the base <NUM>, a protective housing <NUM> coupled to the base <NUM>, a rotatable permeable member <NUM> disposed within the protective housing <NUM>, and a gas inlet <NUM> is indirectly coupled to the rotatable permeable member <NUM> (e.g., the gas inlet <NUM> can be indirectly coupled the rotatable permeable member via the bracket <NUM> and/or rotary union <NUM>). The driving mechanism <NUM> can provide rotation. The driving mechanism <NUM> includes a rotatable component 150a. In some implementations, the driving mechanism <NUM> is a motor, and the rotatable component 150a is a rotatable shaft. In some implementations, the driving mechanism <NUM> is a gearbox, and the rotatable component 150a is a gear shaft.

The protective housing <NUM> is defined by a lateral wall 102a extending between a first end 102b and a second end 102c. The first end 102b is coupled to the base <NUM>. The protective housing <NUM> defines multiple perforations 102d configured to pass liquid through the lateral wall 102a of the protective housing <NUM>.

The rotatable permeable member <NUM> has a body defining a longitudinal axis "X1" (see <FIG>) and can be axially rotated about the longitudinal axis X1. The rotatable permeable member <NUM> is coupled to the rotatable component 150a of the driving mechanism <NUM> (for example, the rotatable shaft of the motor or the gear shaft of the gearbox), such that the rotatable permeable member <NUM> rotates with the rotatable component 150a of the driving mechanism <NUM>.

In some implementations, such as in a gearbox driven system, the rotatable component 150a may be attached to the top of the shaft, and an entire drive shaft can be hollow. In such an example, gas is introduced above the surface of the liquid through the rotatable component 150a, and passes through the drive shaft and into the rotatable permeable member. The gas inlet <NUM> is configured to provide gas to the rotatable permeable member <NUM> through an indirect or direct coupling. The rotatable permeable member <NUM> is configured to expel gas through its pores. Liquid passing through protective housing <NUM> can shear the gas from the surface of rotating permeable member <NUM> to generate nano-bubbles from the gas.

The base <NUM> is coupled to the driving mechanism <NUM> (for example, the motor) by attaching the base <NUM> to the driving mechanism <NUM>, for example, by one or more screws and/or a latch. The base <NUM> can secure one or more of the non-rotating portions of the device <NUM> (such as the protective housing <NUM>) to a non-rotating portion of the driving mechanism (for example, a stator of the motor <NUM>). Although shown in <FIG> as being generally circular, the base <NUM> can have any shape.

In various embodiments, the protective housing <NUM> is an optional component. The protective housing <NUM> can protect the components of the device <NUM> residing within the protective housing <NUM> (such as the rotatable permeable member <NUM>) from coming in contact with foreign objects, such as stones, rags, or any other large solids that may be suspended in the surrounding liquid, as well as any other materials that may damage the inner components of the device <NUM>. In some implementations, the protective housing <NUM> is coupled to the base <NUM> by welding, so the base <NUM> and the protective housing <NUM> form a unitary body. The perforations 102d pass liquid through the protective housing <NUM>, so that liquid can flow to and from the inner components of the device <NUM> (such as the rotatable permeable member <NUM>), as illustrated in <FIG>. Although shown in <FIG> as being generally circular, the perforations 102d can have any shape. The perforations 102d can be of uniform size or varying size. The perforations 102d can be uniformly or randomly distributed across the protective housing <NUM>. The protective housing provides the benefit of allowing liquid to flow freely to the internal components of the device (e.g., the rotatable permeable member <NUM>) while preventing debris (e.g., fibrous plants) from becoming entangled with the internal components.

The rotatable permeable member <NUM> can define multiple pores along its wall. In various implementations, the pores are positioned along the wall such that the center of each pore (along at least one transverse plane) is approximately equidistant from the longitudinal axis. Gas (such as air, oxygen, nitrogen, or ozone) can be supplied to the rotatable permeable member <NUM>. As the permeable member <NUM> rotates, it simulates turbulent flow above the turbulent velocity threshold (e.g., <NUM>/s or higher) in the surrounding liquid (e.g., water). This liquid then shears the gas exiting the pores to form the nano-bubbles dispersed in the surrounding liquid. Some non-limiting examples of materials that can be used to construct the rotatable permeable member <NUM> include metal, ceramic, and plastic. Although shown in <FIG> as being generally cylindrical, the rotatable permeable member <NUM> can have another shape, such as elongate member having an obloid cross-section. The rotatable permeable member <NUM> is described in more detail later.

The gas inlet <NUM> is configured to couple to a gas source, such as a blower or air pump or any other compressed gas source, so that gas can be introduced into the rotatable permeable member <NUM>. In some implementations, the gas inlet <NUM> includes a pipe fitting 104a. In some implementations, the gas inlet <NUM> includes a gas tubing fitting 104b that can be coupled to the gas source.

The device <NUM> includes a rotary union <NUM> coupled to the rotatable permeable member <NUM> and/or to some or all of the other components of the device. A portion of the rotary union <NUM> coupled to the rotating permeable member <NUM> can rotate with the rotating permeable member <NUM>, while a remaining portion of the rotary union <NUM> does not rotate with the rotating permeable member <NUM>. For example, the rotating portion of the rotary union <NUM> can reside within a non-rotating housing of the rotary union <NUM>. The gas inlet <NUM> can be coupled to the non-rotating portion of the rotary union <NUM>. The rotary union <NUM> and the gas source can be coupled to opposite ends of the gas inlet <NUM>. For example, the rotary union <NUM> can be coupled to a first end of the pipe fitting 104a, and the gas tubing fitting 104b can be coupled to a second end of the pipe fitting 104a opposite the first end. Gas can flow from the gas source, through the gas inlet <NUM> and into the rotatable permeable member <NUM> either directly or indirectly (for example, through a shaft and/or rotary union <NUM>). The rotary union <NUM> can include a radial bearing that prevents radial deviation of the rotating portion of the rotary union <NUM> with respect to the non-rotating portion of the rotary union <NUM>.

The device <NUM> also includes a tube support <NUM> coupled to the rotatable permeable member <NUM>. The tube support <NUM> can be coupled to opposite ends of the rotatable permeable member <NUM> along the axis of rotation of the rotatable permeable member <NUM>. The rotatable permeable member <NUM> is disposed within the tube support <NUM> in certain implementations. The rotatable permeable member <NUM> and the tube support <NUM> can be tubular members that are concentrically aligned. The tube support <NUM> can rotate with the rotatable permeable member <NUM>. In some implementations, the tube support <NUM> is attached to the permeable member <NUM> (for example, by welding). In some implementations, the tube support <NUM> and the rotatable permeable member <NUM> are formed as a unitary body. The tube support <NUM> reduces or eliminates the twisting moment on the rotatable permeable member <NUM> in various implementations.

In <FIG>, the tube support <NUM> has a cylindrical body defined by a first wall (e.g., top wall), a second wall (e.g., bottom wall), and a tubular side wall extending between the first and second wall. The tube support <NUM> has an outer diameter that is larger than the outer diameter of the rotatable permeable member <NUM>. In some implementations, the tube support <NUM> can define multiple perforations. The perforations can allow liquid to flow to and from the rotatable permeable member <NUM>. The perforations can be disposed on a surface of the tube support <NUM>'s first wall, the second wall, the side wall, or combinations thereof. The perforations can be circular, semi-circular, rectangular, cubical, oblong, triangular, slotted, finned, and the like. The perforations can be of uniform size or varying size (e.g., the perforations can be gradually increase in size along an axial length of the tube support). The perforations of the tube support <NUM> are substantially larger than the pores of the permeable member <NUM> in various implementations. The perforations of the tube support may have the same or different shape as the pores of the permeable member <NUM>. The perforations can be uniformly or randomly distributed across the tube support <NUM>. Other examples of the tube support <NUM> are shown in <FIG>.

Once the liquid has been aerated by the nano-bubbles generated by the rotating rotatable permeable member <NUM>, it is desirable to transport the nano-bubble-containing liquid away from the rotatable permeable member <NUM>, so that new liquid (which does not contain the nano-bubbles released from the rotatable permeable member) can flow to a surface (e.g., an outer surface) of the rotatable permeable member <NUM> and become aerated. Inducing surrounding liquid flow to and from the rotatable permeable member <NUM> can allow for continuous generation of nano-bubbles. During operation as the tube support <NUM> and the rotatable permeable member <NUM> rotate together, surrounding liquid can flow into the inner volume of the tube support <NUM> through perforations on the end surfaces of the tube support <NUM>. The rotatable permeable member <NUM> can be rotated (for example, by the motor <NUM>) at a rotational surface velocity that is equivalent to a transaxial flow rate that is equal to or greater than turbulent velocity of the liquid at the surface of the rotatable permeable member <NUM>. Simulated turbulent flow of the surrounding liquid at a level above the turbulent threshold can promote the formation of nano-bubbles by shearing gas from the surface of the rotatable permeable member <NUM> to form the nano-bubbles and preventing them from coalescing. The rotational surface velocity can be considered to be simulating turbulent flow if the equivalent transaxial flow rate has a Reynolds number is greater than <NUM>,<NUM>. The simulated turbulent flow performs the function of shearing gas bubbles from the surface of the rotatable permeable member <NUM>.

During operation, the rotation of the tube support <NUM> can cause the liquid (with nano-bubbles generated by the rotatable permeable member <NUM>) to flow radially outward through the perforations on the lateral surface of the tube support <NUM>. The rotation of the tube support <NUM> provides the function of removing newly formed nano-bubbles from the vicinity of the surface of the rotatable permeable member <NUM> to prevent nano-bubble coalescence. Actual flow is produced by the action of the tube support <NUM> and the arrangement of the perforations defined by its various surfaces. When the tube support <NUM> is rotated, nano-bubble-containing liquid contained within the cavity between the rotatable permeable member and the tube support is flowed radially away from the rotatable permeable member and is replaced by new liquid flowing in from the perforations at the end surfaces of the tube support <NUM>. Therefore, the rotation of the tube support <NUM> promotes circulation of the surrounding liquid to and from the surface of the rotatable permeable member <NUM> and therefore promotes the continuous generation of nano-bubbles.

The device <NUM> can include a bracket <NUM>. The bracket <NUM> can be coupled to the housing <NUM> (for example, the second end 102c of the housing <NUM>). In some implementations, the bracket <NUM> is welded to the housing <NUM>. The bracket <NUM> can define an inner bore within which the rotary union <NUM> can reside. The bracket <NUM> can prevent rotation of the non-rotating portion of the rotary union <NUM> (for example, the housing of the rotary union <NUM>), while the rotating portion of the rotary union <NUM> rotates with the rotatable permeable member <NUM>. The bracket <NUM> can include a slot within which the gas inlet <NUM> can reside. In some implementations, the slot of the bracket <NUM> can prevent rotation of the gas inlet <NUM>. For example, the slot of the bracket <NUM> can prevent the gas inlet <NUM> (which is coupled to the rotary union <NUM>) from rotating with the rotary union <NUM>.

The device <NUM> can include an optional plate <NUM>. The plate <NUM> can be coupled to and cover an end of the protective housing <NUM> (for example, the second end 102c of the protective housing <NUM>). In some implementations, the plate <NUM> and the base <NUM> are coupled to opposite ends of the protective housing <NUM>.

The plate <NUM> can be used as a support for the device <NUM>. For example, the plate <NUM> can provide a flat surface that allows the device <NUM> to rest stably on the floor or bed of a body of water. Various components of the device <NUM> can be coupled to the plate <NUM> to secure the components in place. For example, the bracket <NUM> can be coupled to the plate <NUM> with screws. In some implementations, the non-rotating portion of the rotary union <NUM> is coupled to the plate <NUM>. Although shown in <FIG> as being generally circular, the plate <NUM> can have any shape. Various components of the device <NUM> can be centered or eccentrically positioned on the plate <NUM>. For example, the housing <NUM> and the bracket <NUM> can be centered on the plate <NUM>. Although shown in <FIG> as having a larger outer diameter than the housing <NUM>, the plate <NUM> can have an outer diameter that is the same as the housing <NUM>.

In some implementations, the device <NUM> includes a driving mechanism that can rotate the rotatable permeable member <NUM>. For example, the device <NUM> can include the motor <NUM> including the rotatable shaft 150a. For example, the device <NUM> can include a gearbox (not shown). The driving mechanism can be configured to rotate at a pre-set range of rotational speed. The driving mechanism can be configured to rotate at several different pre-set ranges of rotational speed (for example, the rotational speed of the driving mechanism can be changed without steps over a range), for example, the driving mechanism can include a variable-speed drive. The driving mechanism can be submerged in, partially submerged in, or above the liquid in which aeration is desired. In some implementations, the motor <NUM> can be an electric motor, for example, an AC motor, a DC motor, a stepper motor, or a servo motor. In some implementations, the motor <NUM> is a battery-powered motor. In some implementations, the device <NUM> includes a right-angle gear box such that the motor <NUM> can be mounted above a volume of liquid (e.g., body of water).

In some implementations, the device <NUM> includes one or more impellers 150b coupled to the driving mechanism. Rotation of the one or more impellers 150b can induce liquid flow into and out of the tube support <NUM> (thereby promoting circulation of liquid) while nano-bubbles are generated by the rotatable permeable member <NUM>.

<FIG> shows the device <NUM> shown in <FIG> in assembled form. Gas <NUM> (such as oxygen, an inert gas (e.g., nitrogen), ozone, or air) is provided to the gas inlet <NUM>. Gas <NUM> can flow directly or indirectly from the gas inlet <NUM> to the rotatable permeable member <NUM> (shown in <FIG>, but obstructed from view in <FIG> by the perforated housing <NUM>). As the gas <NUM> flows through the pores of the rotatable permeable member <NUM> during rotation of the rotatable permeable member <NUM>, nano-bubbles 140a are generated and dispersed in the liquid <NUM> flowing into and out of the tube support <NUM> (shown in <FIG>, but obstructed from view in <FIG>) and the protective housing <NUM>.

In some implementations, the apparatus provided herein can operate in a medium that contains a composition that includes a liquid, such as a slurry (for example, a mixture of solid and liquid). Some non-limiting examples of the liquid <NUM> include liquids including water (such as pond water, wastewater, or produced water) and cement slurries. Flow of the liquid <NUM> into and out of the tube support can be induced, for example, by rotation of one or more impellers (not shown). The rotation of the various components of the device <NUM> (such as the rotatable permeable member <NUM>) can be provided by a driving mechanism, for example, the motor <NUM>.

<FIG> show various views of the device <NUM>. <FIG> shows a top view of the device <NUM> in assembled form. <FIG> shows a side view of the device <NUM> in assembled form. <FIG> shows cross-section of the side view shown in <FIG>. <FIG> shows a side view of the device <NUM> with the housing <NUM> removed. <FIG> shows cross-section of the side view shown in <FIG>. <FIG> shows an exploded side view of the device <NUM>. <FIG> shows cross-section of the exploded side view shown in <FIG>.

<FIG> shows a top cross-sectional view of the rotatable permeable member <NUM> and the tube support <NUM> rotating within the protective housing <NUM>. As gas <NUM> is injected into the rotatable permeable member <NUM> and exits the rotatable permeable member <NUM>, nano-bubbles 140a are formed by the gas <NUM> exiting the pores (103a, not shown) and shearing force of the surrounding liquid <NUM> simulating turbulent flow above the turbulent threshold at the outer surface of the rotatable permeable member <NUM>.

<FIG> show various views of a few optional, non-rotating components of the device <NUM>, such as the base <NUM>, the protective housing <NUM>, and the bracket <NUM>. <FIG> shows a top perspective view of those non-rotating components of the device <NUM> in assembled form. <FIG> shows a bottom perspective view of those non-rotating components of the device <NUM> in assembled form. <FIG> shows a side view of those non-rotating components of the device <NUM> in assembled form. <FIG> shows a cross-section of the side view shown in <FIG>.

<FIG> show various views of a few rotating components of the device <NUM>, such as the rotatable permeable member <NUM> and the tube support <NUM>. <FIG> shows a top perspective view of those rotating components of the device <NUM>. <FIG> shows a bottom perspective view of those rotating components of the device <NUM>. <FIG> shows a side view of those rotating components of the device <NUM>. <FIG> shows a cross-section of the side view shown in <FIG>. The tube support <NUM> can advantageously move liquid away from rotatable permeable member to prevent the coalescence of nano-bubbles.

<FIG> shows another example of the tube support <NUM>. The rotatable permeable member <NUM> can be positioned within the tube support <NUM>. The rotatable permeable member <NUM> (not shown) can pass through a central inner bore of the tube support <NUM>. <FIG> shows another example of the tube support <NUM>. The tube support <NUM> surrounds the rotatable permeable member <NUM>. As shown in <FIG>, the tube support <NUM> can include one or more vanes.

<FIG> shows an enlarged view of the rotatable permeable member <NUM>. The rotatable permeable member <NUM> defines multiple pores 103a through which gas <NUM> can exit to generate the nano-bubbles 140a. The pores 103a can have a diameter that is less than or equal to <NUM>. In some implementations, the pores 103a have a diameter that is in a range of from <NUM> to <NUM>. The pores 103a can be of uniform size or varying size. The pores 103a can be uniformly or randomly distributed across a surface (e.g., outer surface) of the rotatable permeable member <NUM>. The pores 103a can have any regular (e.g., circular) or irregular shape.

The rotatable permeable member <NUM> can couple to and rotate with a driving mechanism (not shown), such as a motor (<NUM>) coupled to a gearbox. Gas <NUM> is flowed into the rotatable permeable member <NUM>. As the rotatable permeable member <NUM> rotates, the gas <NUM> exits through the pores 103a, where the surrounding liquid (e.g., water) shears them off under simulated turbulent flow conditions above the turbulent threshold to generate nano-bubbles 140a dispersed in the surrounding liquid. The surrounding liquid <NUM> can be, for example, water in which the introduction of one or more gases (e.g., aeration) is desired. During operation of the device <NUM>, it is preferred that enough of the rotatable permeable member <NUM> is submerged in the liquid <NUM>, so that all of the pores 103a are below the surface of the liquid <NUM>.

In some implementations, non-structural factors that can affect the size of generated nano-bubbles 140a, such as the composition of the gas <NUM> being flowed into the rotatable permeable member <NUM>, the rate at which the gas <NUM> is being flowed into the permeable member <NUM>, the supply pressure of the gas <NUM> being flowed into the rotatable permeable member <NUM>, the composition of the surrounding liquid <NUM>, the flow rate (if any) of the surrounding liquid <NUM>, and the pressure of the surrounding liquid <NUM>.

According to the claimed invention and as shown in <FIG>, the rotatable permeable member <NUM> includes one or more radially-extending members <NUM> to facilitate liquid flow along its surface. The radially-extending member <NUM> is configured to move the liquid away from an outer surface of the body of the rotatable permeable member and simulate turbulent flow above the turbulent threshold in the liquid that allows the liquid to shear gas from the outer surface of the rotatable permeable member, thereby forming nano-bubbles in the liquid. For example, in some embodiments, non-limiting examples of the radially-extending members <NUM> include wings (see <FIG>), vanes (see <FIG>), or propeller (see <FIG>). A radially-extending member can be fixedly coupled to (or be integral with) the exterior surface of the rotatable permeable member <NUM> to move liquid away from rotatable permeable member to prevent nano-bubble coalescence. The tube support <NUM> is not required to facilitate flow within the device and, thus, is optional.

In some implementations, the radial-extending members <NUM> can be coupled to the tube support <NUM> or/and the rotatable permeable member <NUM> (e.g., like a hub and spoke configuration).

<FIG> is a flow chart of a method <NUM> for liquid aeration. The method <NUM> can be implemented, for example, using the aeration device <NUM>. At step <NUM>, a liquid (for example, the surrounding liquid <NUM>) is flowed across a surface (e.g., outer surface) of a rotatable permeable member (for example, the rotatable permeable member <NUM>). The liquid <NUM> can be flowed across the surface of the permeable member <NUM>, for example, by submerging the rotatable permeable member <NUM> in the liquid <NUM>. A perforated housing (for example, the housing <NUM>) can surround the rotatable permeable member <NUM>. In some implementations, once the rotatable permeable member <NUM> is submerged in the liquid <NUM>, flow of liquid <NUM> can be induced, for example, by one or more rotating impellers. For example, the motor <NUM> can rotate one or more impellers to induce flow of liquid <NUM> into and out of the tube support <NUM>, which surrounds the rotatable permeable member <NUM>.

At step <NUM>, a gas (for example, the gas <NUM>) is flowed into the rotatable permeable member <NUM>. The gas <NUM> can be flowed into the rotatable permeable member <NUM>, for example, by a blower or air pump connected to the gas inlet <NUM>. In some implementations, the pressure of the gas <NUM> flowing into the rotatable permeable member <NUM> is at least <NUM> atmosphere (atm). In some implementations, the pressure of the gas <NUM> flowing into the rotatable permeable member <NUM> is at most <NUM> atm. In some implementations, the pressure of the gas <NUM> flowing into the rotatable permeable member <NUM> is in a range of from <NUM> atm to <NUM> atm, or <NUM> atm to <NUM> atm. In some implementations, the pressure of the gas <NUM> flowing into the rotatable permeable member <NUM> is in a range of from <NUM> atm to <NUM> atm.

At step <NUM>, the rotatable permeable member <NUM> is rotated to generate nano-bubbles (for example, the nano-bubbles 140a) from the gas <NUM> and expel the generated nano-bubbles 140a to the liquid <NUM> around the surface of the rotatable permeable member <NUM>. The rotatable permeable member <NUM> can be rotated at step <NUM> by a driving mechanism, such as a rotating shaft 150a of a motor <NUM> or a gearbox. The tube support <NUM> rotates with the rotatable permeable member <NUM>. The rotatable permeable member <NUM> (and tube support <NUM>) can be rotated at step <NUM> at a rotational speed that simulates turbulent flow above the turbulent threshold of the surrounding liquid <NUM> at the rotating surface of the rotatable permeable member <NUM> to form nano-bubbles.

<FIG> is a flow chart of a method <NUM> for liquid aeration. The method <NUM> can be implemented, for example, using the aeration device <NUM>. At step <NUM>, at least a portion of a rotatable permeable member (for example, the rotatable permeable member <NUM>) is submerged in a liquid (for example, the surrounding liquid <NUM>). As described previously, the rotatable permeable member <NUM> is disposed within the housing <NUM> defined by the lateral wall 102a extending between the first end 102b and the second end 102c. The housing <NUM> defines multiple perforations 102d on its lateral wall 102a to promote flow of the liquid into and out of the housing. In some implementations, the tube support <NUM> can define multiple blade or wing structures (see, for example, <FIG>) to facilitate flow of the liquid to and from the rotatable permeable member <NUM>. The rotatable permeable member <NUM> is coupled to the rotatable shaft 150a of the motor <NUM>. At step <NUM>, gas (such as the gas <NUM>) is introduced into the rotatable permeable member <NUM> either directly or indirectly through a gas inlet (for example, the gas inlet <NUM>). At step <NUM>, the rotatable shaft 150a couples to the rotatable permeable member <NUM> is rotated, thereby generating nano-bubbles (for example, the nano-bubbles 140a) from the gas <NUM>. In various implementations, rotating the rotatable shaft 150a at step <NUM> includes rotating the rotatable permeable member <NUM> (and the tube support <NUM>) at a rotational speed that simulates flow at or above the turbulent threshold of the surrounding liquid <NUM> at the surface of the rotatable permeable member <NUM> (similar to step <NUM> of method <NUM>).

Any of the devices (or apparatuses), and methods described herein include producing nano-bubbles having a mean diameter less than <NUM> in a liquid volume (e.g., body of water). In some embodiments, the nano-bubbles have a mean diameter ranging from about <NUM> to about <NUM>, about <NUM> to about <NUM>, or about <NUM> to about <NUM>. The nano-bubbles in the composition may have a unimodal distribution of diameters, where the mean bubble diameter is less than <NUM>. In some embodiments, any of the compositions produced by the devices (or apparatuses), and methods described herein include nano-bubbles, but are free of micro-bubbles.

Claim 1:
An apparatus for producing nano-bubbles in a volume of liquid, the apparatus comprising:
a motor (<NUM>) comprising a rotatable shaft (150a);
an axially rotatable permeable member (<NUM>) including a body having a wall and a plurality of pores through which gas introduced into the axially rotatable permeable member can flow,
the axially rotatable permeable member couplable to a gas inlet (<NUM>) configured to introduce gas from a gas source into the axially rotatable permeable member, the axially rotatable permeable member coupled to the rotatable shaft of the motor and adapted to rotate along with the rotatable shaft;
wherein the axially rotatable permeable member, when rotated, is adapted to move the liquid away from an outer surface of the body of the axially rotatable permeable member and simulate 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, characterized in that the axially rotatable permeable member further comprises at least one radially-extending member (<NUM>).