Patent Publication Number: US-2022227646-A1

Title: Floating water treatment apparatus

Description:
PRIORITY CLAIM 
     This application is a utility filing from and claims priority to U.S. Provisional Application No. 63/138,825, filed on Jan. 19, 2021, the entire disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     The present disclosure relates to wastewater treatment systems and processes, and particularly to ecological and biological treatment systems. More specifically, the disclosure concerns systems and methods for treating wastewater and for using the byproducts of such treatment, particularly as a “green” or renewable energy source. 
     U.S. Pat. No. 7,776,211 (the &#39;211 Patent), the entire disclosure of which is incorporated herein by reference, discloses a wastewater treatment system that incorporates a rotating biological contactor (RBC), such as the RBC apparatus  30  shown in  FIG. 1 . The RBC apparatus  30  utilizes algae and bacteria to advantageously biologically treat the wastewater, employing technology described in U.S. Pat. Nos. 5,647,983, 5,755,961, and 6,158,386, the disclosures of which are all incorporated herein by reference. The RBC apparatus  30  includes a media wheel  40  that is supported within a tank  32  for rotation about a central axis defined by an axle  41 . It is understood that the wheel can rotate about the axle or that the wheel can be fixed to the axle with the axle rotating about a support. The media wheel  40  includes air capture members, or vanes,  43  that are used to rotate the wheel within the wastewater contained in the tank. In particular, a jet or flow of air is provided by an external air pump and directed through an air inlet  35  to impinge on the vanes  43  to rotate the wheel. The vanes are preferably configured to, in effect, capture an air pocket between successive vanes so that the relative buoyancy of the air pocket will rotate the wheel as the air pocket rises within the tank. 
     In the illustrated embodiment, the media wheel  40  includes a biological filter media  45  contained in one portion of the wheel that is configured to support bacterial growth. Treatment of the wastewater requires bringing the nutrients within the wastewater into contact with bacterial colonies that use the nutrients as food. The wastewater level within the tank  32  is maintained so that the filter media  45  will be alternately submerged in and lifted out of the wastewater, which beneficially enhances the transfer of oxygen and CO 2  between the bacterial colony and the wastewater. While one portion or half of the wheel interior is filled with the biological filter media  45 , the remaining portion or half  46  is empty. Thus, as the media wheel  40  rotates, the filter media  45  alternately displaces the wastewater, producing a continuous movement or surge of the wastewater within the tank  32 . This continuous movement increases the nutrient removal rate or capability of algae that grows on the vanes of the wheel  40  and that is suspended within tank  32 . The media wheel is configured to support algae growth, such as by the provision of multiple vanes  43  to provide significant surface area on which the algae may grow. 
     The air jet at the inlet  35  is beneficial for the growth of the algae because the air jet foams and fractionates the wastewater. This foam  48  collects at the surface of the water between the media wheel  40  and the walls of the container. This foam bears against the wheel and more particularly the algae growing thereon so that the algae can readily extract the necessary nutrients from the entrained bio-solids within the foam. It can be appreciated that the algae growing on the wheel forms a biomass that can be used for bio-diesel, fertilizer and other “green” uses. The RBC apparatus  30  thus contemplates that the algae will be continuously dislodged from the wheel and allowed to pass into a tertiary treatment tank. The air jet through inlet  35  can dislodge algae from the wheel once the algae colony reaches a critical mass. Once removed from the wheel, the algae biomass exits tank  32  through outlet  34  which can communicate with a further treatment tank. 
     One embodiment of the wastewater treatment system  110  of the &#39;211 Patent is shown in  FIG. 2 . The system  110  includes a tank  112  that contains multiple media wheels  125  arranged in a series of rows and columns within the tank. Walls  113  separate each media wheel  125  with a weir  114  defined in each wall to establish a common water level within the tank. Wastewater flows through the tank  112  at a water level L that is controlled to maintain an optimum height within the container. In order to maintain optimum conditions for algae growth, it is desirable to control the amount of exposure of the algal colonies to the sunlight as the media wheels  125  rotate. If the water level L is too low, a greater portion of the circumference of the wheels is exposed to sunlight, and conversely if the water level is too high. In either case, too much or too little sunlight can compromise the desired conditions for optimum algae growth. Too little algae reduces the treatment capability of the system and reduces the biosolids produced by the system. The level control  117  may be a conventional float valve positioned at the opening of the outlet  116  within the container  112 . Since sunlight is critical to the function of the system  110 , the container  112  is provided with a translucent or transparent lid  124  that keeps debris and wildlife from interfering with the operation of the system  110 . The system  110  includes an air pump  121  that feed air to the media wheels through corresponding air tubes  122 . 
     The rotating biological contactor technology shown in  FIG. 1 , is implemented in a recirculating aquaculture system (RAS) disclosed in U.S. Pat. No. 9,380,766, the entire disclosure of which is incorporated herein by reference. Thus, as shown in  FIG. 3 , a system  200  includes several media wheels  227 , with the vanes  228  and biological media  229  similar to the RBC apparatus  30 , disposed in a tank  209 . A plurality of air diffusers  226  are disposed in the tank beneath the media wheels to direct air to the vanes  228  as described above. In this application of the media wheel technology, a surge pump  203 , fed by an air supply line  204 , forces an air and water mixture into the tank  209 . Water exits the tank at outlet  210  and is fed through a valve  212  to a clarifier  213 , from which solids are drained at valve  218 . A light  225  is supported by a frame  224  above the media wheels  226  to provide a light source for the tanks. It is contemplated that the tank houses fish and/or other aquatic creatures, so the media wheels  227  are necessary to process the biological waste of the creatures. The algae generated by the RAS not only helps process the waste but also adds to the oxygen level in the tank, which reduces the volume of air that must be supplied by the surge pump. 
     In the systems described above, the RBC apparatus is supported within a tank by a fixed support frame. This arrangement requires custom tanks and support frames be constructed to maintain proper water levels for the RBC apparatus to operate. Lagoon type wastewater treatment plants cannot meet the current treatment levels required by regulatory agencies. Therefore, many of them are being replaced by advanced mechanical plants that incorporate the fixed RBC apparatus at great expense to the wastewater utility. In most cases, multiple RBC apparatuses are required, each of which are mounted within the tank by a fixed support. For instance, a municipal wastewater treatment facility may include dozens, and even hundreds, RBC apparatuses, all requiring a fixed support within a custom tank. 
     SUMMARY OF THE DISCLOSURE 
     A rotating biological contactor (RBC) includes a media wheel having a plurality of vanes configured for growth of algae thereon. The plurality of vanes are oriented and configured to cause the media wheel to rotate when air impinges on the vanes such that when the media wheel is partly immersed in water, rotation of the media wheel alternately exposes algae growing on the plurality of vanes to sunlight and to the water. In certain embodiments, the RBC includes a frame connected to an axle of the media wheel, whereby the media wheel rotates about a central axis relative to the frame. An air diffuser connected to a source of air is provided and is arranged in an operating position to direct air to impinge on the plurality of vanes when the media wheel is partly immersed in water. In one feature of the disclosure, one of the media wheel and the frame is constructed with a buoyancy sufficient to support the media wheel partly immersed in water during rotation of the media wheel. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a rotating biological contactor (RBC) apparatus used in embodiments of the present disclosure. 
         FIG. 2  is a side view of a wastewater treatment system using the RBC apparatus shown in  FIG. 1 . 
         FIG. 3  is a side view of an aquaculture system using the RBC apparatus shown in  FIG. 1 . 
         FIGS. 4A-C  are top, side and end views of a floating RBC apparatus according to one embodiment of the present disclosure with one embodiment of an air diffuser. 
         FIGS. 5A-C  are top, side and end views of the floating RBC apparatus shown in  FIGS. 4A-C , with a second embodiment of an air diffuser. 
         FIGS. 6A-C  are top, side and end views of a further embodiment of a floating RCS apparatus according to the present disclosure. 
         FIG. 7  is a diagram of a floating RBC apparatus as disclosed herein, as used in a wastewater treatment system. 
         FIG. 8  is a diagram of a floating RBC apparatus as disclosed herein, as used in an aquaculture system or fish grow-out pen. 
         FIG. 9  is a diagram of a tank including multiple floating RBC apparatuses. 
     
    
    
     DETAILED DESCRIPTION 
     For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the disclosure is thereby intended. It is further understood that the present disclosure includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles disclosed herein as would normally occur to one skilled in the art to which this disclosure pertains. 
     In one aspect of the present disclosure, an independent floating support frame carries an RBC (rotating biological contactor) apparatus, such as the apparatus  30 , so that the apparatus is always maintained at an optimum operating water level, whether within a tank or in a body of water, such as a retention pond. This feature allows a plurality of RBC apparatuses to be installed without the need for specialized frames or tank constructions, and allows the RBC apparatuses to be installed in a free body of water that does not have any structure, such as a tank wall, to support a fixed support frame. In another aspect, the RBC is sufficiently buoyant to support itself at an optimum operating water level. 
     Thus, in one embodiment, the floating assembly  300  shown in  FIGS. 4A-C  includes a frame structure  304  configured to support an RBC apparatus  302 , which can be configured like the apparatus  30  described above. The, RBC apparatus  302  can particularly include a wheel  303 , like the wheel  40 , constructed as described in U.S. Pat. Nos. 5,647,983, 5,755,961, and 6,158,386, the disclosures of which are all incorporated herein by reference. The frame structure  304  can be formed from elongated members  304   a  and  304   b  joined at joint elements  304   c  to form a generally rectangular frame. The frame structure can be formed of any buoyant material, preferably a plastic material such as ABS, polycarbonate, PVC and nylon. The elongated members are preferably circular in cross-section, but other cross-sectional shapes are contemplated. The frame structure  304  is preferably rectangular, as depicted in  FIGS. 4A-C , although other configurations are contemplated. The elongated members  304   a,    304   b  are preferably sized to be slightly larger than the profile of the RBC apparatus  302 , while providing sufficient clearance between the apparatus and the frame so as to not interfere with the operation of the RBC apparatus. The elongated members are preferably hollow but sealed to capture air inside the frame structure to ensure the buoyancy of the assembly  300 . The hollow interior can be filed with a further buoyant material, such as a foam, to enhance the ability of the assembly  300  to float. It is understood that the frame structure  304  need not float directly on the surface of the water, but can be slightly submerged, provided the media wheel is supported so that rotation of the wheel can alternatively expose the algae growing on the vanes to sunlight and to the water. 
     The wheel  303  of the RBC apparatus  302  includes an axle  306  that defines a central axis about which the vanes  307  rotate. Thus, as described above, the wheel  303  can rotate about the axle  306 , or the wheel can be fixed to the axle with the axle rotating about the frame structure  304 . The frame structure  304 , and particularly the elongated members  304   a,  include inward hubs  304 d for engaging the axle  306 . The hubs can be integrally formed with the elongated members or can be separately attached to the members. If the hubs are integral with the elongated members the hubs are preferably solid to ensure that the overall frame structure is air-tight. 
     As shown in  FIGS. 7-8 , the floating assembly  300  can be disposed within a body of water, whether a wastewater lagoon or a tank, for a wide range of uses—from wastewater treatment ( FIG. 6 ) to a fish grow-out pen ( FIG. 7 ). Since the entire assembly floats, it follows the water level—from the high-water level position  300 ′ to the low-water level position  300 ″. The RBC apparatus carried by the floating frame structure continues to operate under any water level condition. As explained above, the RBC apparatus  302 / 30  requires air flow against the vanes  307  to rotate the apparatus to alternately expose the vane surfaces to light and water. In the embodiment of  FIGS. 4A-C , an air diffuser  310  is positioned below each floating assembly  300  in an operating position so that a flow of air, whether as bubbles or a continuous jet, impinges on the vanes to rotate the apparatus. In this embodiment, the diffuser  310  is connected to an air feed pipe structure  312  that is placed at the bottom of the body of water. In order to ensure that the air diffuser  310  is aligned with the RBC apparatus  302 , the floating assembly  300  can be tethered to the pipe structure to ensure that the assembly does not float out of range of the diffuser. It can be appreciated that the tether must accommodate changes in the water level, allowing the assembly to remain floating regardless of water level. The position of the RBC apparatus  302  relative to the air diffuser  310  is optimized so that the air flow upward onto the vanes can rotate the vanes at an optimum speed. Thus, in the illustrated embodiment, the air from the air diffuser impinges on the vanes at a location corresponding to about ½ the radius between the axle  306  and the vanes  307 . 
     In another embodiment, the air diffuser is incorporated into the floating assembly, as shown in  FIGS. 5A-C . The floating assembly  350  includes a frame structure  354  that is similar to the frame structure  304  and is configured to support an RBC apparatus  302 . The frame structure  354  includes elongated members  354   a,    354   b  joined at joints  345   c,  again similar to the frame structure  304 . However, in one modification, an air diffuser  360  is carried in its operating position beneath the RBC apparatus by a separate frame structure  362 . The separate frame structure  352  is affixed to the elongated members  354   a  so that the air diffuser  360  can span the frame structure  354  and so that the air diffuser  360  is properly aligned, in its operating position, with the vanes  307  of the RBC apparatus for maximum rotational effect. In particular, the frame structure  352  and air diffuser are submerged below the media wheel  303 . The air diffuser  360  is connected to a fitting  363  that is configured to be connected to an air supply, such as through flexible tubing connected to an air manifold associated with the body of water. The air diffuser  360  can be in the form of a hollow tube with apertures spaced along the length of the tube directed toward the RBC apparatus. 
     It can be appreciated that incorporation of the air diffuser  360  into the floating assembly  350  guarantees proper alignment of the air leaving the diffuser and the vane of the RBC apparatus. Thus, the floating assembly shown in  FIGS. 5A-C  does not require a tether to maintain the proper positioning of the RBC apparatus. In this embodiment, movement of the floating assembly  350  is essentially only limited by the connection between the fitting  363  of the air diffuser and the air manifold. The air connection or tubing is configured to allow the floating assembly  350  to move between the high and low water level positions  300 ′ and  300 ″, respectively, in  FIGS. 7-8 . In a further modification, the air manifold system that supplies air to the air diffuser  360  of each assembly within a given body of water can have a particular buoyancy that allows the manifold to reside at a predetermined depth within the body of water, even as the water level rises and falls. 
     In a further embodiment, shown in  FIGS. 6A-C , the assembly  400  is free floating, like the assembly  350 . The assembly includes an RBC apparatus  402  that is constructed like the RBC apparatuses  302  and  30 , and that is rotationally supported on a frame  404 . In particular, the frame  404  includes upper horizontal members  404   a  that support the axle  406  of the RBC apparatus. The horizontal members are connected to vertical members  404   b  that extend downward on either side of the RBC apparatus  402  and that are connected to a lower horizontal member  404   c.  The frame  404  is thus provided in a rectangular form, as shown in  FIG. 6C . An air supply tube  410  terminates in a diffuser  411  that is mounted to the lower horizontal member  404   c  and that is oriented in its operating position beneath the RBC apparatus to direct air upward onto the vanes  407 . The air supply tube  410  can be connected to an air pump that is maintained outside the body of water on which the assembly  400  floats (see  FIGS. 7-8 ). It is contemplated that the air supply tube can be integrated into the lower horizontal member  404   c,  such as in the form of an internal passageway connected to the air supply tube and including openings forming the air diffuser  411 . 
     In one feature of the assembly  400 , the lower member  404   c  does not float and does not have sufficient buoyancy to seek the surface of the body of water. This feature ensures that the air diffuser  411  is maintained directly below the RBC apparatus  402  so that the air bubbling upward from the diffuser will always impinge directly on the vanes  407  to rotate the media wheel  403 , as is necessary for the RBC apparatus  402  to operate as described above. The frame, and particularly the horizontal member  404   c,  can be weighted or can be formed of a material that does not float or that lacks sufficient buoyancy to seek the water surface. 
     In order for the assembly  400  to float on the surface of the body of water, the media wheel  403  is formed of a buoyant material that is sufficiently buoyant to maintain the media wheel at the surface of the water, as shown in  FIG. 7-8 , or more particularly to maintain the upper horizontal members  404   a  of the frame and the axle  406  of the RBC apparatus at the surface. In one specific embodiment, the media wheel is formed of a polypropylene with gas bubbles entrained within the material. The gas bubble density depends on the size of the frame and the weight of the algae growing on the media wheel  403 . In one specific embodiment, the gas-entrained polypropylene has a volume ratio of gas bubbles to polypropylene of 20%. In the specific embodiment, the entrained bubbles are formed by intermingling polymer beads with nitrogen filled beads. The co-mingled polymer and gas beads are placed in a mold and heated to melt the polymer material of the polymer beads and the gas beads. The polymer fills the mold while the gas, which can be nitrogen for instance, is released from the gas beads but entrained within the polymer body. 
     It is contemplated that a given body of water can include many RBC floating assemblies, such as the assemblies  300 ,  350 ,  400 . The assemblies can float freely within the body of water as long as the assemblies are situated above a corresponding air diffuser. The assembly  300  does not include its own air supply, so some means must be provided to ensure that the assembly is aligned vertically with an air diffuser  310 . This can be accomplished by tethering each assembly  300  to a corresponding diffuser. Alternatively, the entire surface of the body of water can be filled with side-by-side assemblies  300 , each positioned above an air diffuser. The assemblies  350 ,  400  include their own air diffuser so a tether or other mechanism for restraining the assembly is not required. In these embodiments, the assemblies  350 ,  400  can float freely in the body of water, but it is understood that their movement will be restrained by the air supply tube that is connected to the external air pump. 
     In one use, a tank T includes a plurality of RBC floating assemblies  400 , as shown in  FIG. 9 . The assemblies are free-floating within the tank but a sufficient number of assemblies are provided so that the assemblies generally maintain their position within the tank even as they rotate. A series of air diffusers, such as the diffusers  312  can be arranged at the bottom of the tank to direct air bubbles upward to the assemblies. In accordance with one aspect of the disclosure, the assemblies are packed within the tank T but are arranged so that the media wheels of adjacent assemblies rotate in opposite direction. Thus, the media wheel of the left uppermost assembly rotates in the counter-clockwise (CCW) direction, while the immediately adjacent assembly rotates in the clockwise (CW) direction. Similarly, in the right lowermost assembly  400  rotates in the CCW direction while the immediately adjacent assembly rotates in the CW direction. As appreciated from  FIGS. 6A-6C , the media wheel  403  and vanes  407  of the assembly  400  are protected from contact with adjacent assemblies  400  in a direction transverse to or perpendicular to the direction of rotation by the vertical members  404   b  of the frame  404 . However, the wheel and vanes are exposed in the direction of rotation, meaning that there is no frame structure protecting the wheel from contact with adjacent floating assemblies  400 . However, it has been found that if the wheels of adjacent floating RBC assemblies rotate in opposite directions the assemblies do not contact each other in the direction of rotation. In one modification the frame  404  of the floating RBC assemblies  400  in the tank T can be eliminated. In this modification, the media wheel  403  is essentially a stand-alone rotating wheel, propelled by air bubbles from the air diffuser  312 . As long as the media wheels are arranged in alternating directions of rotation (i.e., CCW-CW-CCW-CW, etc.) the media wheels were continue to rotate and continue to promote algae growth. 
     It can be appreciated that the floating RBC systems disclosed herein can be added to existing aeration tanks at a wastewater treatment plant without the need to construct new tanks or modify the existing tanks. The air diffusers needed for operation of the RBC apparatus can be the existing aeration features already present in the wastewater treatment protocol. 
     As noted above, lagoon-type wastewater treatment plants, which use natural ponds rather than tanks, cannot meet the treatment levels required by regulatory agencies. However, for lagoon-type wastewater plants, the floating RBC systems disclosed herein can be added directly into the lagoons. This would allow the existing lagoons to comply with more stringent treatment requirements without having to construct a new mechanical treatment plant. 
     Existing outdoor aquaculture systems employ net pens to grow fish in ponds, lakes, and offshore facilities. These types of aquaculture systems create and release untreated wastes from the fish which can damage or destroy the surrounding natural ecosystem. The floating RBC systems disclosed herein can be installed within lined aquaculture raceway systems which can trap and treat the fish wastes, eliminating impacts on the surrounding ecosystems. 
     For existing indoor aquaculture or recirculating aquaculture systems (RAS), the floating RBC systems disclosed herein can be added into the existing fish tanks and the existing aeration system within the fish tanks can serve as the air diffuser to rotate the RBC apparatus. Again, the introduction of the floating RBC system of the present disclosure eliminates the need to construct new aquaculture tanks or modify the existing tanks. 
     The present disclosure should be considered as illustrative and not restrictive in character. It is understood that only certain embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the disclosure are desired to be protected.