Patent Publication Number: US-2004055960-A1

Title: Directional wastewater aerator and method

Description:
CROSS REFERENCE TO RELATED APPLICATION AND CLAIM TO PRIORITY  
     [0001] This application is based on provisional application Ser. No. 60/409,185, filed Sep. 10, 2002, for Willie B. McNeill, Jr., the disclosure of which is incorporated herein by reference and to which priority is claimed under 35 U.S.C. § 120. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] The invention relates to a wastewater aerator having curved baffles to direct the wastewater in a desired direction.  
       BACKGROUND OF THE INVENTION  
       [0003] Conventional wastewater treatment facilities typically include a number of vessels or tanks, which are interconnected through pipes, pumps, and similar plumbing for treating wastewater. Some facilities may include a surge tank for smoothing fluctuations in wastewater input, and a number of subsequent processing tanks.  
       [0004] Treatment of wastewater at a conventional facility may involve three major stages. The primary treatment stage includes a settling tank, wherein the densest sludge of the wastewater is separated, and removed and sent to an incinerator. The remaining effluent then undergoes secondary treatment, which may involve the biochemical consumption of organic material in one or more basins. Aerobic microorganisms consume organic pollutants in wastewater. Because the bacteria are aerobic, their efficiency of consumption is dependent upon the level of oxygen dissolved in the wastewater. The higher the level of dissolved oxygen in the effluent, the faster the rate of bacterial consumption of organic pollutants. As such, aeration of the effluent is desirable so that the bacteria efficiently consume the organic wastes. Tertiary treatment may be simple or extensive depending on the extent of pollution and the local requirements for water purity. Inorganic pollutants may be removed during tertiary treatment, as well as any organic pollutants not removed during the primary and secondary stages.  
       [0005] To achieve adequate aeration for consumption of the organic pollutants, aeration basins may include aerator devices or systems for adding oxygen to the effluent. One conventional wastewater treatment facility is disclosed in U.S. Pat. No. 5,110,465, for Willie B. McNeill, Jr., the inventor of which is the inventor the present invention, and the disclosure of which is incorporated herein by reference. In the &#39;465 patent, this disclosed facility comprises an optional surge basin, an aeration basin, a settling basin, and a digester basin. Each basin has an assembly for supplying fluid treated therein to the next interconnected basin. An aerator is provided in the aeration basin for causing fluid flow thereabout.  
       [0006] Various aerator devices have been developed for use in aeration basins, including brush aerators, paddle wheel type aerators and horizontal aerators. Such devices fail to effectively pull wastewater from the bottom of the aeration basin, where the concentration of dissolved oxygen is relatively low. As such, they fail to effectively aerate and mix the fluid in the vessel.  
       [0007] Other devices draw wastewater from the vessel, and spray the wastewater throughout a 360° direction above the wastewater surface. Such devices require a relatively large amount of energy. Therefore, they are not cost efficient. In addition, concrete guides are typically required within the basin so that wastewater flow may be controlled and contained within a particular area of the basin. Such guides further increase system complexity and cost.  
       [0008] Therefore, there is a need for an aerator device that directs the wastewater flow path when the wastewater is being discharged from the aerator device, which effectively mixes and aerates the wastewater, and that is cost efficient.  
       SUMMARY OF THE INVENTION  
       [0009] A directional aerator comprises a float, an uptake pipe extending through said float, and a means for pulling a flow of wastewater into the uptake pipe. The wastewater flow is vertically displaced upwardly through the uptake pipe. At least one pair of baffles deflects the flow of wastewater upon discharge.  
       [0010] A method of aerating a fluid is disclosed. A floating aerator having an uptake pipe is provided. Fluid is pulled into the uptake pipe, and vertically displaced upwardly through the uptake pipe. The flow of fluid is deflected in a selected direction upon discharge, forming an aeration ditch. 
     
    
    
     DESCRIPTION OF THE DRAWINGS  
     [0011]FIG. 1 is a side elevational view, with portions shown in phantom, of a directional aerator according to a first embodiment of the present invention;  
     [0012]FIG. 2 is a cross-sectional plan view, with portions shown in phantom, of a directional aerator according to the first embodiment;  
     [0013]FIG. 3 is a cross-sectional plan view, with portions shown in phantom of a directional aerator according to the first embodiment with flow path arrows;  
     [0014]FIG. 4 is a top plan view of an aeration basin with directional aerators according to the present invention;  
     [0015]FIG. 5 is a cross sectional view of the aeration basin of FIG. 4 taken along line  5 - 5  and viewed in the direction of the arrows;  
     [0016]FIG. 6 is a side elevational view, with portions shown in phantom, of a directional aerator according to a second embodiment;  
     [0017]FIG. 7 is an exploded assembly view of a directional aerator according to the second embodiment;  
     [0018]FIG. 8 is a top plan view of a directional aerator according to the second embodiment with flow path arrows;  
     [0019]FIG. 9 is a top plan view of a directional aerator according to the second embodiment; and  
     [0020]FIG. 10 is a top plan view of a directional aerator according to the second embodiment with flow path arrows. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0021] As best shown in FIG. 1, a directional aerator  10  according to one embodiment of the present invention comprises a float  12 , which maintains buoyancy on the wastewater surface  14  within an aeration vessel or area. Float  12  has a first major surface  16  and a second major surface  18 , with side surfaces  20  therebetween. An uptake pipe  22  extends through first and second major surfaces  16  and  18  of float  12 . Uptake pipe  22  includes a lower portion  24 , which extends downwardly from second major surface  18  and into the wastewater below wastewater surface  14 . Uptake pipe  22  also includes an upper portion  26 , which extends upwardly toward first major surface  16 , above wastewater surface  14 . Preferably lower portion  24  includes a curved end or elbow portion  28 . Elbow portion  28  may be substantially parallel with first and second major surfaces  16  and  18  of float  12 . Elbow portion  28  includes an intake  29  into which fluid is pulled. Intake  29  may be substantially perpendicular to lower portion  24 .  
     [0022] The length of lower portion  24  may be adjusted depending on the system requirements. For example, a relatively long lower portion  24  may be required for deep basins or ponds in order to place intake  29  closer to the bottom of the basin. The length of lower portion  24  may be adjusted at the time of manufacture depending on customer specifications. Lower portion  24  may then be welded onto aerator  10 . Alternatively, lower portion  24  and elbow portion  28  may be joined by a flange or conventional spacer used to connect pipes. A standard length for lower portion  24  may be provided when aerator  10  is constructed, for example twenty-four inches in length. If a longer uptake pipe  22  is required, elbow portion  28  may be removed, and an extension pipe joined between and interconnecting lower portion  24  and elbow portion  28 .  
     [0023] Intake  29  draws wastewater from the deepest portion of the vessel, where there is normally the least amount of oxygen. The wastewater is vertically displaced upwardly through uptake pipe  22 , and then discharged above wastewater surface  14  so that aeration may occur. It is more efficient to add oxygen to a liquid having a relatively low dissolved oxygen level, compared to adding oxygen to a liquid with a higher dissolved oxygen level. This is because the aerobic bacteria only use a limited amount of oxygen during the consumption process. If more oxygen than the bacteria can use is provided through inefficient aeration methods, the excess aeration represents an unnecessary cost in energy required for running the aerator. Drawing wastewater from near the bottom of the vessel, where dissolved oxygen level is the lowest in the basin, is therefore an efficient method of aerating and mixing the wastewater.  
     [0024] Aerator  10  may include an impeller  30  operably associated with a motor  32  to pull the wastewater into intake  29 , as show by arrows F. Preferably, motor  32  is a sealed electric motor, which typically requires a minimal amount of maintenance. For example, sealed electric motor  32  may require lubrication once per year, or possibly once about every eight months if motor  32  is operated 24 hours a day, seven days a week. The horsepower (hp) of motor  32  is dependent on system requirements, but may be in the range of between about 3 hp to about 75 hp. In addition, the diameter of float  12  may vary, and also may affect the hp requirements of motor  32 . For example, a 20 hp motor  32  may be fitted to a float  12  having a diameter of about 7 feet. A 40 hp motor  32  may be fitted to a float  12  having a diameter of about 9 feet. Thus, as the hp of motor  32  increases, the diameter of float  12  preferably increases.  
     [0025] Generally, no lubrication is required for other components of aerator  10 . An impellor shaft  31  connects impeller  30  with motor  32 . Other means for pulling fluid through aerator  10  may also be used, such as a pump. Impeller  30  may be positioned within uptake  22  adjacent second major surface  18 , so that impeller  30  is just below wastewater surface  14 . A motor base plate  33  may be provided, so that wastewater is not pulled into motor  32 .  
     [0026] As best shown in FIGS. 1 and 2, directional baffles  34  extend from uptake pipe  22 , above first major surface  16  of float  12 . Three pairs A, B and C of directional baffles  34  are shown in FIGS. 2 and 3. However, more or fewer baffles  34  may be provided, depending on the particular system requirements. As such, pairs A, B, C are shown for purposes of explanation only, and the disclosed embodiment is not so limited.  
     [0027] Each of directional baffles  34  comprises a crescent-shaped plate, having a first end  36  and a second end  38 . First ends  36  are secured to uptake pipe  22  adjacent first major surface  16  of float  12 . Alternatively, first ends  36  may also be secured to a corresponding sleeve  40  surrounding a discharge outlet  42  of uptake pipe  22  adjacent first major surface  16 . Preferably, pair C of directional baffles  34  is smaller than pair B, which is smaller than pair A.  
     [0028] The wastewater flow path F is vertically displaced upwardly toward directional baffles  34  by impellor  30 , and directed outwardly therefrom in a desired direction, as best shown in FIG. 3. Motor base plate  33  (the circumference shown in phantom in FIGS.  2 - 3 ) prevents wastewater from continuing upwardly toward motor  32 . Directional baffles  34  are positioned so that second ends  38  point toward the desired direction of discharge, wherein second ends  38  of pair A are positioned in an outermost position relative to discharge outlet  42 , pair C are positioned in an innermost position relative to discharge outlet  42 , and pair B are positioned therebetween.  
     [0029] Wastewater is pulled into intake  29 , and vertically displaced upwardly by impellor  30  to discharge outlet  42 . As shown by arrows F indicating the flow path of discharging wastewater in FIG. 3, the wastewater is deflected in a desired direction. Some wastewater exits discharge  42  already proceeding in the desired direction, and is simply deflected outwardly by motor base plate  33 . Some wastewater is deflected into pair A of baffles  32 , channeled between pairs A and B and motor base pate  33  toward ends  38 , and then discharged outwardly from aerator  10 . Some wastewater is deflected into pair B of baffles  32 , channeled between pairs B and C and motor base plate  33 , and discharged outwardly from ends  38 . Some wastewater is deflected by pair C and motor base plate  33 , and discharged outwardly from ends  38 .  
     [0030] The wastewater is discharged above wastewater surface  14  in a predetermined discharge pattern based on the orientation and angle of baffles  34  relative to discharge outlet  42 . Wastewater may be discharged onto wastewater surface  14  in a single direction, which creates velocity in a circulation channel, or aeration ditch, as best shown in FIGS. 4 and 5.  
     [0031] A circulation basin B is provided, with the flow path and direction of wastewater shown by arrows F. The shape of basin B is for purposes of explanation only. Aerator  10  may be used in aeration vessels and tanks having various configurations, or even deep aeration ponds. Aerator  10  draws wastewater into intake  29  from near the bottom of the basin B, as best shown in FIG. 5. The wastewater is then vertically displaced and directed from discharge outlet  42  in a desired direction, forming an aeration ditch in basin B.  
     [0032] An aeration ditch is a closed loop around which wastewater is circulated within basin B (or some other vessel) by aerator  10 . Aeration ditches are very energy efficient because the momentum of the mass of wastewater causes a continuous motion, as best shown in FIG. 4. Aerator  10  maintains a continuous wastewater flow using a relatively small amount of energy by pulling the wastewater from near the bottom of the vessel and directing the flow to form an aeration ditch. The created aeration ditch effectively mixes the fluid. In addition, wastewater is efficiently aerated since aerator  10  aerates the wastewater from near the bottom of the aeration basin B.  
     [0033] Conventional aeration systems typically require a relatively large amount of energy to achieve high levels of mixing and aeration, or fail to effectively aerate the wastewater from near the bottom of the vessel. In addition, many conventional systems include gearboxes and/or hydraulic drives, which are expensive and require a relatively large amount of maintenance. Many conventional systems also include long hollow shafts, which may be prone to bearing failures.  
     [0034] Aerator  10  eliminates the need for gearboxes and/or hydraulic drives, and requires minimal maintenance. Preferably, all wetted components of aerator  10  are made of stainless steel, including float  12  and uptake pipe  22 . Float  12  may also be formed from reinforced fiberglass.  
     [0035] Aerator  10  may be maintained at a selected position on wastewater surface by securing cables or pipes to clasps  44 , as best shown in FIGS. 1 and 4. Clasps  44  may be mounted on side surfaces  20  of float  12 . Preferably, two clasps  44  are provided on side surfaces  20 , and are perpendicular to the wastewater discharge flow. The cables may be secured to the sidewalls of the vessel or basin, or to an adjacent walkway or bridge. Alternatively, aerator  10  may be anchored to the bottom of the vessel, basin or pond. Preferably, the cables or pipes maintain aerator  10  at a determined position on wastewater surface  14 , but allow aerator to rise or lower as the level of wastewater surface  14  fluctuates. In this way, aerator  10  may float on wastewater surface  14 . Hinged pipes or tensioned cables may be used to maintain the positioning of aerator  10 . Efficiency is achieved even during periods when fluid in the vessel is relatively low, or during peak flow periods, such as during heavy rains or contributory flows into the vessel.  
     [0036] Aerator  10  may be easily modified to account for the width of a particular vessel and/or the mixing pattern required for the geometry of the vessel. Such modification is accomplished by modifying the shape and orientation of directional baffles  34 . Baffles  34  may be angled or curved relative to discharge outlet  42  so that the discharge pattern is either relatively wide or relatively narrow. The desired discharge pattern is determined based on system requirements and customer specifications. The orientation and curvature of baffles  34  may then be modified at the time of manufacture.  
     [0037] A directional aerator  50  according to another embodiment is best shown in FIG. 6. Aerator  50  is similar to aerator  10 , but includes directional baffles  52 , as best shown in FIG. 7. Each baffle  52  is U-shaped, and includes a first end  54  and a second end  56 . The curvature of baffles  54  is relatively gradual, and not as sharp as the curvature of baffles  34 . First ends  54  of baffles  52  extend from a central mounting rib  58 , and curve around discharge outlet  42 . Central mounting rib  58  extends from discharge outlet  42  to first ends  54 , so that first ends  54  are spaced from discharge outlet  42 .  
     [0038] Aerator  50  may also include at least one pair of directional mounting ribs  60 . Directional mounting ribs  60  function in a similar manner to smaller baffle pair C in aerator  10 . Directional mounting ribs  60  angle outwardly relative to discharge outlet  42 , but need not parallel the angle of curvature of baffles  52 . Directional mounting ribs  60  and central mounting rib  58  work in conjunction with directional baffles  52  to deflect the wastewater flow in a desired direction and discharge pattern, as best shown in FIG. 8 by arrows F. The curvature of baffles  52 , and the angle of directional mounting ribs  60  relative to discharge outlet  42  may be adjusted depending on system requirements.  
     [0039] Aerator  50  may also include an extended mounting rib  62 , as best shown in FIGS.  6 - 10 . Extended mounting rib  62  extends outwardly on first major surface  16  in line with the path of the wastewater being discharged. Extended mounting rib  62  may also be coplanar and in line with central mounting rib  58 , wherein central mounting rib  58  extends from discharge outlet  42  to first ends  54  and extended mounting rib  62  extends in an opposite direction from discharge outlet  42 . Extended mounting rib  62  balances aerator  50  by offsetting the weight difference created by baffles  52  on first major surface  16  of float  12 .  
     [0040] An electrical cord-mounting bracket  64  may be secured to an end of extended mounting rib  62 , proximate side surfaces  20  of float  12 . A power supply cord C may be connected to electrical cord mounting bracket  64 , aligned with extending mounting rib  62  and providing power to motor  32 . Aerator  50  may float on wastewater surface  14  adjacent a walkway or bridge, aligned with the discharge flow. As such, the power supply cord C is aligned with, and easily attached to, electrical cord mounting bracket  64 . In addition, electrical cord mounting bracket  64  provides that the power supply cord C is above the discharge flow.  
     [0041] Aerator  50  may also include a motor base plate  66 , as best shown in FIGS.  6 - 10 . Motor base plate  66  ensures that wastewater is deflected away from motor  32  upon discharge from discharge outlet  42 , and outwardly from aerator  50  by baffles  52  in a desired direction. In this way, clogging and/or other damage to motor  32  is minimized.  
     [0042] Preferably, aerator  50  also includes an extended directional base plate  68 , as best shown in FIGS. 6, 7 and  9 . Extended directional base plate  68  is secured to and intermediate motor base plate  66  and baffles  52 . Extended directional base plate  68  may include a U-shaped inner edge  70 , which aligns with discharge outlet  42 , and an outer edge  72  aligned with baffles  54 . Inner edge  70  may also be secured to and overlap directional mounting ribs  60  and central mounting rib  58 . Extended directional base plate  68  deflects and channels wastewater flow against baffles  54  and ribs  58 ,  60 , as best shown in FIG. 10 by arrows F.  
     [0043] A controller C may be provided for controlling the volume of wastewater being discharged, as best shown in FIG. 4. Aerator  50  (or  10 ) may be controlled to adjust for organic load (oxygen demand) fluctuations in the vessel by regulating the speed of aerator  50  (or  10 ). If a relatively heavy amount of flow is being input into basin B, the volume of wastewater being discharged may be adjusted accordingly by increasing the speed of aeration via controller C.  
     [0044] Controller C is preferably remote from aerator  50  (or  10 ), such as on a walkway or bridge adjacent the vessel being aerated. The controller may include a variable frequency drive (“VFD”) that is in communication with oxygen meters in the vessel. The oxygen meters sense the dissolved oxygen level of the wastewater, and communicate the sensed information to the VFD via a 4-20 milliamp signal. The VFD controller may then regulate the oxygen requirements by increasing or decreasing the speed of aerator  50  (or  10 ). In this way, a selected dissolved oxygen level may be maintained, even if the hydraulic flow and organic load is variable.  
     [0045] Generally, the strength of wastewater is not variable. However, the hydraulic flow of wastewater into the aeration vessel (such as basin B) may fluctuate significantly depending on the time of day. An increase in hydraulic flow increases the organic load and demands an increased speed of oxygenation. The VFD may increase oxygenation by speeding up aerator  50 . This adjustment tends to match the oxygen level requirement to the organic demand caused by such increased hydraulic flows. Thus, the speed and volume of discharge from aerator  50  (or  10 ) is adjusted to either increase or decrease aeration. In this way, a selected dissolved oxygen level of the wastewater may be maintained based on the monitored levels.  
     [0046] Certain aspects of the present invention have been explained with reference to particular embodiments. However, it will be apparent to one of ordinary skill in the art that various modifications and variations may be made in construction or configuration of the present invention without departing from the scope or spirit of the invention. Therefore, it is intended that the present invention include all such modifications and variations provided they come within the scope of the following claims and their equivalents.