Abstract:
An Aerator/Digester for treating wastewater comprises cylindrical chamber having a centrally disposed air pipe supported from the chambers closed bottom end and extending along a longitudinal axis of the cylindrical chamber and beyond the upper end. The air pipe includes at least one aperture pattern comprising plural interleaved rows of relatively small diameter holes and larger diameter holes. When air under pressure, is introduced through the air pipe, a Venturi effect is created to draw wastewater into the chamber via ports formed near the closed bottom end and out via one or more outlet ports proximate to the upper end. The apertures are drilled through the air pipe at an angle to the vertical with the small diameter apertures inclined at an upward angle and the larger diameter apertures at a downward angle which has been found to enhance the circulation of the wastewater.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     This invention relates generally to apparatus for treating waste water, aerating ponds, and for eliminating the buildup of fats, oils, greases found in pump lift stations, wet wells and grease interceptors encountered in water treatment facilities, and more particularly to a compact device for increasing the oxygen content of water and for simultaneously pulverizing organic solids that may be present in the water being treated. 
     II. Discussion of the Prior Art 
     In the McGuffin U.S. Pat. No. 7,963,508 there is described an apparatus for aerating liquids and for enhancing digestion of solid organic materials present therein by microbial action. The device serves to pulverize organic solids into micron sizes, allowing bacteria to more readily process the material. The apparatus comprises and elongate tubular housing have a solid, preferably heavy, base to anchor the housing in a vertical disposition within a pond or vessel in which the water to be treated is contained. The housing has three inlet ports spaced 120 degrees apart near the base and an open top. Positioned over the open top is a circular manifold comprising a plurality of concentric ridges. An air feed conduit is centrally disposed within the housing and extends from the base upward through the manifold where it is adapted to be connected to a source of pressurized air. The air feed conduit includes a plurality of apertures through a wall thereof at a location offset from the bottom end thereof, just above the three inlet ports. To stabilize the air feed conduit, three walls or partitions extend between the air feed conduit and the interior wall of the tubular housing, effectively dividing the housing into three chambers, each encompassing one of the three inlet ports. 
     When air, under pressure, is applied to the upper end of the air feed conduit, bubbles are created in the water in which the device is submerged and the rising bubbles create a Venturi effect to draw water into the housing through the inlet ports. The air increases the oxygen content of the water and as the flow exits the open top of the housing, it is made to impinge on the stepped concentric edges on the manifold to break up organic solids present in the waste water. 
     As is explained in detail below, the present invention is similar in many respects to the McGuffin device described above, but various non-obvious and novel modifications have been incorporated into the preferred embodiment of the present invention to improve the efficiency, reduce the cost, prolong the useful life and lower the maintenance cost when compared to the McGuffin apparatus. 
     SUMMARY OF THE INVENTION 
     The present invention has a tubular housing defining a cylindrical chamber with a closed and weighted bottom end and an open upper end. Water inlet ports are located near the base and water exits the open top. A stack of concentric equilateral triangles of diminishing side length is disposed proximate the upper end of the housing. Passing vertically downward through a central hole in the stack is an airflow tube whose lower end is threaded into a tapped bore at the center of the base that closes off the bottom end of the tubular housing. As such, the rigid airflow tube is supported upright of the base. This obviates the need for the partitions employed in the McGuffin apparatus that it needs to stabilize and support the air feed conduit. 
     In the present invention, the air exit ports drilled in the air flow tube are in a pattern of alternating rows of small diameter holes and larger diameter holes. Device application dictates the drill angle of the holes. The smaller series of holes are drilled at a range of 10 degrees to a maximum upward angle of about 30 degrees to the longitudinal axis of the housing and the larger holes are drilled at a range of 0 degrees to a maximum downward angle of about 60 degrees. In this manner, larger size bubbles are directed downward before rising. This has been found to enhance the Venturi draw of water through the housings bottom inlet ports while the smaller holes in the air tube result in smaller size bubbles for improving aeration of the water as they rise to exit the barrel housings water outlet ports. Because of the size difference in the bubbles, there is less combining of the two. The flow stream is also directed against and impinges on the edges of the stacked triangles before exiting the housing. This serves to continuously pulverize material that repeatedly recirculates through by re-entering the chamber through the lower water inlet ports. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment, especially when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts. 
         FIG. 1  is a top plan view of the aerator/digester comprising a preferred embodiment of the present invention; 
         FIG. 2  is a front cross-sectional view taken along the line  2 - 2  in  FIG. 1 ; 
         FIG. 3  is a cross sectional view taken along the line  3 - 3  in  FIG. 2 ; 
         FIG. 4  is an enlarged side view of the stationary triangular impingement member seen in  FIG. 2 ; 
         FIG. 5  is an enlarged partial view of the air tube shown in  FIG. 2  illustrating a preferred air discharge hole pattern formed in the air tube; 
         FIG. 6  is a segment of the wall of the air tube showing the angles at which the holes are drilled therein; and 
         FIG. 7  is a vertical, cross-sectional view of a further embodiment of the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The description of the preferred embodiment is intended to be read in conjunction with the accompanying drawings which are to be considered part of the entire written description of this invention. In the description, relative terms such as “lower”, “upper”, “horizontal”, “vertical”, “above”, “below”, “up”, “down”, “top”, and “bottom” as well as derivatives thereof (e.g., “horizontally”, “downwardly”, “upwardly”, etc.) should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms such as “connected”, “connecting”, “attached”, “attaching”, “join”, and “joining” are used interchangeable and referred to one structure or surface being secured to another structure or surface or integrally fabricated in one piece, unless expressly described otherwise. 
     Referring to  FIGS. 1 and 2 , a first embodiment of the Aerator/Digester is indicated generally by numeral  10  and is seen to comprise a tubular housing  12  in the form of a right circular cylinder with an upper end  14  and a lower end  16 . Without limitation, the housing may have a diameter of about 10¾ inches, a height dimension of 34 inches, and a wall thickness of about inches. It may comprise a non-corrosive material such as polyvinylchloride (PVC) or stainless steel. 
     Fitted into the upper end  14  of the tubular housing  12  is a plug  18  having an aperture  20  formed through its thickness dimension and located at the center thereof. Located approximately 4 inches above the lower end  16  of the housing  12  is an internal seal plate  22  beneath which is a ballast member  24 . The ballast member may be concrete or other heavy material such as stainless steel with concrete being preferred due to its low cost. An external bottom cap  26  fits over the bottom end of the housing to serve as a base. 
     The seal plate  22  and the ballast member  24  have a centrally disposed vertical bore  28  which may be threaded or unthreaded. 
     Located just below the top plug  18  are three inverted U-shaped openings, equally spaced about the perimeter of the housing, only one of which is visible in  FIG. 2  and is identified by numeral  30 . Again, without limitation, the sides of the U-shaped openings  30  may be 7 inches apart and the circular arch joining the two sides may have a radius of 3 inches. The three U-shaped apertures function as discharge openings as will be further explained below. 
     Located just above the seal plate  22  proximate the bottom end of the housing  12  are three equally spaced apart circular apertures in the housing wall, only one of which is visible in  FIG. 2  and is identified by numeral  32 . The apertures  32  function as waste stream entrance ports. 
     Referring next to  FIGS. 3 and 4 , it will be seen that affixed to the underside of the top plug  18  is a stationary, triangular impingement member  34 . It comprises a stack of blocks, each forming an equilateral triangle where the blocks are of successively decreasing edge size in progressing from upper to lower when viewed in the side elevation of  FIG. 4 . A circular bore  36  is formed through the thickness of the stack at a center thereof. The members of the stack are preferably composed, but not limited to, a glass-filled polyvinyl chloride polymer material which exhibits a high resistance to abrasion. The three triangular blocks are further processed in a routing operation to add an additional shear surface to each block in the stack. 
     Extending through the cap  14 , the bore  20  and the plug  18 , the bore  36  in the impingement member and into the boar  28  in the ballast member  24  is an air tube  38  whose upper most end  40  is adapted to be connected to a source of air, such as a regenerative blower (not shown). The O.D. of the air tube  38  may provide an interference fit with the bores  20  and  28  to thereby firmly hold the air tube  38  without the need for partition walls as in the McGuffin device. When the ballast member is stainless steel and the bore  28  is threaded, the bottom end of the air tube  38  may also be threaded to screw into the ballast member. The air tube  38  includes a plurality of aperture patterns drilled through the wall thereof, one such pattern indicated generally in  FIG. 2  by numeral  42 . It is located close to, but above, the level of the waste stream entrance ports  32  formed in the wall of housing  12 . Preferably, three such patterns are formed around the circumference of the air tube each being aligned above one of the wastewater entrance ports  32 . 
     As seen in  FIG. 5 , each of the hole patterns  40  form a matrix where rows of relatively large apertures are interleaved with rows of relatively smaller apertures and where the columns of larger apertures are interleaved between columns of smaller apertures. It has been found efficacious to make the small apertures 3/64 inch in diameter and the larger apertures 5/64 inch in diameter. Further, as shown in  FIG. 6 , the apertures in the matrix can be drilled normal to the longitudinal axis of the air tube  38 , but instead the larger apertures are drilled so as to be downwardly inclined at an angle of 60 degree to the horizontal as viewed in  FIG. 6  while the smaller apertures are drilled inward at an angle of about 150 degrees. The angles may be varied depending upon application 
     In use, the Aerator/Digester  10  is placed in a pond or other flooded holding basin such that the weighted bottom of the device  10  rests on a horizontal surface. The upper end  40  of the air tube  38  is then connected to a source of pressurized air, preferably in a range from 1.0 psi to 2.5 psi. The air flows down the air tube  38  and exits the apertures in the pattern of apertures  42 . It is found that air exiting the smaller apertures creates countless smaller diameter bubbles while the air exiting the larger diameter apertures form relatively larger bubbles. Because of the angle at which the apertures in the matrices  40  are drilled, the smaller bubbles float upward such that the profusion thereof mix with the wastewater to aerate same while the larger diameter bubbles are initially directed downward toward the inlet ports  32  before they reverse direction and flow upward in the chamber  44  defined by the interior of the housing  12 . The movement of the larger bubbles proximate the inlet ports  32  and upward therefrom at a high velocity creates a Venturi effect to circulate the wastewater into the chamber  44  through the wastewater entrance ports  32 . As the bubbles rise in the chamber  44 , organic particulate matter that may be present in the wastewater are driven at a high velocity against the impingement member  34  whose sharp corner edges function to pulverize the clumps before exiting the U-shape discharge openings  30 . By increasing the oxygen content of the wastewater and by pulverizing organic matter, aerobic bacteria in the water are better able to thrive and process the increasingly smaller organic substances, thereby improving the quality of the water in which the device  10  is used. As the device runs continuously, wastewater recirculates through the Aerator/Digester  10  with each pass further purifying the wastewater. It has been experimentally determined that the smaller bubbles are not inclined to merge with the larger bubbles and hence improve the efficiency of aeration and promote bacterial digestion of particulates in the waste stream. 
     Turning next to  FIG. 7 , there is shown a longitudinal cross-section of an alternate embodiment of the invention. Like the embodiment of  FIG. 2 , it comprises an outer tubular housing  112 , preferably a right circular cylinder approximately 10 to 12 inches in diameter and about 14 to 26 inches in length. Fabricating the housing  112  from PVC pipe provides a low cost construction. 
     Located approximately 4 inches up from the lower end  114  is a stainless steel ballast slab  116  that is press fit into the ID of the tubular housing  112 . Centrally located in the ballast slab  116  is a threaded bore and threaded into the bore is an externally threaded connector  118  to which an air distribution manifold member  120  is also attached. 
     The air distribution manifold  120  preferably comprises a stainless steel tube about 10 inches in length, 2 inches in diameter and internally threaded at both ends so as to be attachable to the externally threaded connector  118  at its lower end and to an air pipe  122  at its upper end. Attached to the air pipe  122  above the open upper end  124  of the housing  112  is an impingement member  126 . As in the previous embodiment, the impingement member comprising a stack of triangular blocks of diminishing side length made from, but not limited to, a fiberglass impregnated plastic. The impingement member  126  is positioned so that any inorganic materials or large organic material exiting the open top  124  will strike it and further pulverize organic materials so that upon repeated recirculation through the aerator/digester of  FIG. 7  will be better digested by bacteria present in the wastewater being aerated. 
     As in the first embodiment described, a source of compressed air, such as a blower (not shown) is suitably attached by conduit to the upper end  128  of the air pipe  122  which causes streams of bubbles of various sizes exiting the air distribution manifold  120  to rise rapidly up the length of the housing creating by the Venturi effect, a circulation of the wastewater through the inlet ports  123 , up the length of the housing  112 , out its open top  124  and impinging on the exposed edges of the impingement member  126 . While larger diameter bubbles tend to promote circulation, the thousands of smaller size bubbles serve to supply oxygen to the microorganisms responsible for the digestion of organic particulate in the waste stream. 
     Because many varying and different embodiments may be made within the scope of the inventive concept herein taught and because many modifications may be made in the embodiment, herein detailed in accordance with the descriptive requirements of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.