Abstract:
An aeration vessel for use in a aerobic wastewater treatment system, the aeration vessel comprised of a bottom section having a bottom wall and an inverted frustoconical side wall, a top section having a frustoconical side wall and a partition having an inverted frustoconical side wall, the top and bottom sections being provided with mating flanges which can be sealingly engaged, the partition being disposed in the aeration vessel formed by the first and second section.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to aerobic wastewater treatment systems and, more particularly, to an aeration vessel for use in such systems. 
   2. Description of Prior Art 
   Aerobic wastewater treatment systems are generally comprised of three main vessels, a trash or pretreatment vessel, an aeration vessel, and a pump tank. In a typical system, wastewater from a residence, industrial facility, or the like, passes into the pretreatment tank where most of the solids settle out. The effluent from the pretreatment tank then flows into the aeration vessel wherein remaining solids are subjected to aerobic digestion to provide a substantially solids free effluent which then passes into the pump tank for discharge. It is common for the aeration vessel to include an inverted frustoconical partition disposed in the aeration vessel which effectively divides the aeration vessel into an aeration chamber and a clarifier chamber, an oxygen-containing gas being introduced into the aeration chamber, substantially clarified water passing from the clarifier chamber into the pump tank. 
   Typical aeration vessels can be made of concrete, fiberglass, steel, etc., and can be rectangular, cylindrical, etc. Many aeration vessels are made of compositors comprised of fiberglass or similar reinforcing material(s) and a resin, e.g., epoxy, phenolic, etc., and are generally cylindrical in nature. 
   Because of the volume of the tanks, e.g., typically 400 to 1000 gallons, the vessels are quite large and bulky to ship. 
   Aside from being bulky in terms of shipping or transporting the aeration vessels to the desired location, aeration vessels made of composites, have a tendency to be somewhat buoyant with the result that in areas with high water tables or in ground which is highly saturated, they become buoyant enough to have a tendency to at least partially float. 
   Another problem with aeration vessels, particularly cylindrical type, made of composites is that, once in place in the ground, forces acting externally of the vessel by the surrounding earth, can cause the vessels to form cracks at approximately the middle region where the vessel is weakest in terms of having any supporting members to counteract the forces acting on the vessel in that region. In this regard, the bottom and top of the vessel are adequately supported against external, generally radially acting pressure, since the bottom wall and the top wall effectively act as reinforcing ribs. 
   SUMMARY OF THE INVENTION 
   In one embodiment of the present invention, there is provided an aeration vessel comprised of three main components—a first or bottom section having a bottom wall and an inverted frustoconical side wall, a second or top section having a frustoconical side wall, and a partition having an inverted frustoconical side wall. The first and second sections are provided with mating flanges, which can be sealingly engaged, the partition being disposed in the aeration vessel formed by the first and second sections. One preferred feature of the aeration vessel of the present invention is that respective ones of each of the three components are nestable in one another prior to being assembled to form the aeration vessel. Accordingly, multiple aeration vessels, albeit unassembled, can be shipped from a manufacturing location to a distribution location or installation site, the required shipping space being only a fraction of what would be necessary for an equal number of individual fully assembled vessels. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an elevational, cross-sectional view of one embodiment of the aeration vessel of the present invention. 
       FIG. 2  is an elevational, cross-sectional view of another embodiment of the aeration vessel of the present invention; and 
       FIG. 3  is an elevational view, partly in section, showing multiples of the top section, the bottom section and the partition forming the aeration vessel shown in  FIG. 1  nested together and on the trailer of a tractor-trailer for transport. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring first to  FIG. 1 , one embodiment of the aeration vessel of the present invention is shown generally as  10 . Vessel  10  comprises a first or bottom section  12 , a second or top section  14 , and a partition  16 . Bottom section  12  has an inverted frustoconical side wall  18  and a bottom wall  20 . An annular, flange  24  extends radially outwardly from upper edge  22 . 
   Top section  14  comprises a frustoconical wall  26  having a lower edge indicated at  28 . Extending outwardly from lower edge  18  is an annular, flange  30 , flanges  30  and  24  mating in a manner described hereafter. Frustoconical side wall  26  has a first opening  27  and a second opening  27   a . While not necessary, openings  27  and  27   a  are generally diametrically opposed from one another and of equal diameter. Top section  14  further includes an annular, top flange  32  extending radially inwardly from an upper edge  34  of frustoconical side wall  26 . Top flange  32  has an annular, radially innermost edge  36  from which extends an annular connecting wall  38 , connecting wall  38  being connected to a frustoconical neck wall  40 , frustoconical wall  40  terminating in an annular rim  42  defining an opening  44  therein. As shown, opening  44  is covered with a selectively removable hatch or cover  46  to permit access to the interior of vessel  10 . 
   Partition  16  has an inverted frustoconical wall  48  with a bottom mouth or opening  50  defined by the lower edge  52  of inverted frustoconical wall  48 . Partition  16  serves to divide vessel  10  into a clarifier chamber C and an aeration chamber A. As can be seen, partition wall  48  has a lower section  48   a , which terminates in mouth  50  and an upper section  48   b , which forms an upper edge  54  of partition wall  48 . As can also be seen, sections  48   a  and  48   b  are at different angles. More specifically, section  48   a  is at a greater angle relative to an imaginary line, indicated as X, passing axially through the center of partition  16  than is section  48   b . However, as can be seen both sections  48   a  and  48   b  are inverted frustoconical sections. Accordingly, it is to be understood that when the terms “frustoconical,” “frustoconical wall,” “inverted frustoconical wall” or similar terms are used, it is to be understood that such walls can be made up of wall sections or segments having different angles albeit that all such sections are frustoconical or inverted frustoconical in nature. An annular, radially outwardly projecting flange  56  extends from upper edge  54 . Top flange  32  forms an axially downwardly facing, annularly extending connector surface, while flange  56  forms an axially upwardly facing connecting surface, the connecting surfaces being secured together by a series of circumferentially spaced nut and bolt combinations  62  received through registering holes in flanges  32  and  56 . It will be appreciated, however, that partition  16  can be secured to the interior of vessel  10  by other means. For example, flanges  32  and  56  could be secured to one another by means of a suitable adhesive, putty or the like. Additionally, formations could be provided on flanges  32  and  56  to provide a mechanical interlock between partition  16  and top section  14  of vessel  10 . 
   Partition  16  is also provided with an access port  58  in which is received a tapered plug  60 , access port  58  providing an inspection opening. Partition wall  48  also has a second opening  63 , opening  62  being in register with opening  27   a . Openings  62  and  27   a  are adapted to receive a pipe or conduit (not shown) through which clarified water from clarifier chamber C can flow to a pump tank or otherwise for disposal. In assembling aeration vessel  10 , partition  46  would be positioned in top section  14  such that the axially facing connecting surfaces on flanges  32  and  56  would be in register. As noted above, flanges  32  and  56  could then be secured together by a number of techniques. 
   Once partition  16  is positioned in and connected to upper section  14  as described above, upper section  14  can then be secured to lower section  12 . In this regard as noted, flanges  30  and  24 , as seen in  FIG. 1 , are substantially in register, flange  24  having a annular, axially upwardly facing mating surface, flange  30  having an annular, axially downwardly facing mating surface. Flanges  24  and  30  can be secured together to form a fluid-type seal between the axially, downwardly facing mating surface on flange  30  and the axially, upwardly facing mating surface on flange  24 . This can be accomplished in much the same manner that flanges  32  and  56  are secured together. However, in the case of flanges  24  and  30 , fluid-type engagement is necessary since the liquid level in vessel  10  will generally always be above the upper edge of wall  18 . Accordingly, flanges  24  and  30  can be secured together by means of an annular gasket and a circumferential pattern of nut and bolt assemblies, such as nut and bolt assembly  62 . Alternatively, flanges  24  and  30  can be secured together by an adhesive which effectively permanently secures upper and lower sections  14  and  12  together, as well as forming a fluid-type seal. It is also possible for flanges  24  and  30  to be mechanically secured together by interengaging or interlocking formations formed on the flanges. Additionally, segmented, circular clamps equipped with a hose clamp-like tightening mechanism can be used. Such clamps are commonly cylindrical bodies having outwardly extending flanges together, and are provided with a knob such that when the segmented sections are received over the radially outwardly projecting flanges of the cylindrical bodies, turning of the knob results in compressing the two cylindrical bodies together forcing the bodies into fluid-tight sealing with an O-ring received in registering grooves in the cylindrical bodies. It is apparent that such an assembly could be used to sealingly engage flanges  24  and  30 . 
   Turning now to  FIG. 2 , there is shown a slightly modified version of the aeration vessel shown in  FIG. 1 . The vessel shown in  FIG. 2 , differs from that shown in  FIG. 1 , only in the fact that frustoconical wall  26  has a first frustoconical section  26   a , and a second frustoconical section  26   b  which are at different angles. Thus again with respect to an imaginary line indicated as X passing through the center of partition  16 , wall section  26   a  is at a smaller angle to imaginary line X than is wall section  26   b . Likewise, inverted frustoconical wall  18  is comprised of two wall sections  18   a  and  18   b  which are at different angles, wall section  18   a  being at a smaller angle to imaginary line X than wall section  18   b . However, as in the case of partition  16 , all of the various wall section  26   a ,  26   b ,  18   a , and  18   b  are frustoconical or inverted frustoconical in nature. It will also be appreciated that, if desired, partition wall  48  as well as walls  18  and  26  could have three or more frustoconical or inverted frustoconical sections all at different angles to one another but nonetheless all constituting a “single frustoconical” or “inverted frustoconical” wall as noted above. 
   In addition to providing mating surfaces for assembly of upper and lower sections  14  and  12 , respectively, flanges  24  and  30  serve a function of providing an annular reinforcing rib. As was discussed above, in prior art cylindrical vessels, the weakest point in the wall of the vessel is generally at the midpoint between the upper and lower ends of the vessel. It has been found that it is generally in this middle region or section that pressure from the surrounding formation in which the vessel is buried can cause the cylindrical vessels to crack and begin leaking. In the aeration vessel of the present invention, however, the flanges  30  and  24 , cooperating as they do to form an annular reinforcing rib, greatly strengthen vessel  10  in its middle section, i.e., at the juncture formed by flanges  24  and  30 . 
   As noted above, one feature of the aeration vessel of the present invention is that the three major components i.e., bottom section  22 , top section  14  and partition  16 , prior to being assembled to form aeration vessel  10 , are nestable in one another.  FIG. 3  depicts a truck comprised of a tractor  100  and a trailer  102  having a bed  104  for the support of cargo. Resting on bed  104  are stacks of partitions  16 , top sections  14  and bottom sections  12  which are nested on one another for transport purposes. While only 3 each of each of the respective components are showing as being nested or stacked, it will be apparent that the only limitation in the number of such components which can be stacked or nested are height requirements dictated by regulations covering transport of cargo on highways, railways, etc. However, it can clearly be seen that with the uniquely nestable components forming aeration vessel  10 , it is possible to ship what effectively constitutes multiple aeration vessels in a fraction of the space that would be required to ship fully completed vessels, particularly fully completed cylindrical vessels, which of practical necessity must be shipped in fully completed form. By way of example, it can be seen that each of the stacks or nests of the individual components effectively occupy a bed area on bed  104  which would be occupied by a fully completed vessel be it an aeration vessel of the present invention or one of the prior art cylindrical vessels. Thus, assuming that bed  104  had a bed area which would only accommodate the footprints of one each of sections  12 ,  14  and partition  16 , then only three vessels, if in fully completed form and particularly if cylindrical in nature, could be shipped. This is to be contrasted with the present invention wherein the only limitation on the number of vessels, albeit not completed, that could be shipped, are regulations related to height requirements. 
   While the individual components of the aeration vessel can be made of a variety of materials, preferably the three major components described above, are made from a composite where composite is intended to include compositions made of a blend of two or more materials, often non-metallic. For example, fiberglass, composed of glass fibers embedded in a plastic resin matrix. The materials making up the composite complement each other&#39;s strength and eliminate their weaknesses. For example, if one of the components is a fiber such as fiberglass, quartz, kevlar carbon fiber, etc., tensile strength is imparted to the composite while the other component, often called a matrix, usually a resin such as polyester or epoxy that binds the fibers together, most often renders the material stiff and rigid. Additionally, mineral fillers may be added to enhance the flex modulus or the like. Composites are also intended to include aggregates instead of or in addition to fibers. 
   The components of the aeration vessel of the present invention can be made using conventional molding techniques well known to those skilled in the art. 
   The foregoing description and examples illustrate selected embodiments of the present invention. In light thereof, variations and modifications will be suggested to one skilled in the art, all of which are in the spirit and purview of this invention.