Abstract:
A method of removing sediment from the bottom of a settling collects the sediment from the compressed Zone IV layer of sediment adjacent the floor of the settling tank. The process utilizes a fabricated metal sludge collection system having a central truck and a pair of triangularly shaped header wings extending laterally to each side of the central truck. The header wings have an open throat that allows the passage of the Zone IV sediment layer into the header wing, while the diagonally oriented, rearwardly extending side edges of the header wing have elastomeric sweeps attached to prevent the sediment from passing out of the header wing. The sweeps accumulate the sediment at the rearwardly trailing apex of the header wing where a pump extracts the accumulated sediment remotely from the settling tank. A T-connector is formed with a baffle to improve the discharge of sediment from the header wings.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to a water clarification system, and more particularly, to a method of collecting sediment from the bottom of a settling tank and discharging the collected sediment remotely from the settling tank. 
       BACKGROUND OF THE INVENTION 
       [0002]    Rectangular settling tanks are commonly used to remove solids from water collected within water treatment plants before further treatment of the water for consumption. The solids settle to the bottom of the sedimentation basin, which can be a rectangular concrete settling tank, in identifiable layers with the lowermost layer next to the floor of the sedimentation basin being the most dense and compact. Periodically, the collected sludge needs to be removed from the sedimentation basin to maintain the effectiveness and efficiency of the sedimentation basin. 
         [0003]    Removal of the collected sludge is conventionally accomplished by a submerged sludge collector that essentially vacuums the sludge from near the bottom of the settling tank. One such sludge collection system is sold by F. B. Leopold Company under the trademark of Clari-Trac-2™, wherein a transverse header extends on opposing sides of a central cable-driven truck that travels along a linear guide rail to move the transverse header longitudinally along the bottom of the settling tank. Other similar submerged sludge collector systems are sold by MRI, Eimco and Monroe. The transverse header is a conduit that is formed with openings through which the sludge is drawn by a vacuum applied to the transverse header by a flexible hose through which the vacuum is applied by a remote pump. The sludge is collected into the transverse header and then removed from the settling tank through the remote pump. 
         [0004]    A similar sludge removal apparatus is also commercially available through Siemens Water Technologies Corporation under the trademark of Sludge Sucker™ Ovivo also sells commercially a sludge collection system under the trademark of EWT™ Trac-Vac™ Sludge Collector, which also draws sludge from the bottom of the settling tank through a transverse header conduit attached to a central truck that is driven by a pneumatic drive mechanism requiring a flow of compressed air to the central truck. 
         [0005]    Meurer Research, Inc and Monroe Environmental Corporation market a hoseless sludge collector system that incorporates a rigid telescoping conduit to accommodate the movement of the transverse header conduits along the floor of the rectangular settling tanks. As with the other sludge removal systems identified above, the sludge is removed through openings in the transverse header conduit by virtue of a vacuum applied to the transverse header conduit by a pump that is located remotely. The transverse header in each hoseless sludge collection system is mounted on a central truck that is moved along the floor of the settling tank by a cable drive mechanism. 
         [0006]    Brentwood Industries, Inc., through its Polychem Systems Division, has marketed a sludge collection system formed as a pair of triangularly shaped header wings that were suspended from a drive chassis positioned between the header wings to create a negative pressure area beneath the header wings for the purpose of drawing sediment into an extraction apparatus mounted on top of the wing. The header wings were provided with a narrow throat opening that would draw sediment and water through the throat opening due to the negative pressure induced beneath the header wing. This sludge collection system, marketed as the Polychem/WEDA Self-Driven Sediment Pumping System did not completely extract sediment from the lowermost compacted sludge layer next to the floor of the tank. The Polychem/WEDA sludge collection system utilized an electrically driven traction device manufactured by Weda Water, Inc. 
         [0007]    Each of the above sludge collection and removal systems suffers from a similar problem of not entirely removing the lowermost sludge layer adjacent to the floor of the settling tank. Sedimentation in a settling tank falls into four zones. The uppermost zone (Zone I) is referred to as the discrete particle settling zone where sedimentation particles settle without interaction with neighboring particles. The next sedimentation zone (Zone II) is referred to as the flocculent particle zone in which flocculation increases the mass of the sedimentation. The Zone III sedimentation zone is the hindered settling zone where the mass of particles tend to settle as a unit with individual particles remaining in a fixed position relative to one another. The lowermost sedimentation zone (Zone IV) is the compressed or compaction zone where the concentration of particles is so dense that the zone is compacted, which is typically the sludge zone within a settling tank. Each of the above-described systems is configured to sludge that is above the lowermost compressed zone adjacent the floor of the settling tank. Thus, the efficiency of each of these sludge collection and removal systems is less than optimal. 
         [0008]    Nevertheless, these sludge collection systems are an improvement over the earlier sludge collection configurations, such as is depicted in U.S. Pat. No. 6,099,743, granted to John E. Pedersen on Aug. 8, 2000, in which the floor of the settling basin is sloped to drain sludge by gravity and by current flows into a sludge pit at the end of the settling tank where a pump extracts the collected sludge from the pit. In a circular settling tank, the sludge can be swept by a rotating vane into a central pit from which the sludge is pumped to a remote location, as is disclosed in U.S. Pat. No. 6,536,606, issued on Mar. 25, 2003, to Jeffrey J. Schneider. 
         [0009]    It would be desirable to provide a more effective and efficient sludge collection and removal system for use in sedimentation basins, particularly in rectangular settling tanks. It would further be desirable to provide a cable-driven sludge collector formed with header wings to consolidate the collected sludge into an apex where the collected sludge can be removed by a pump or by a vacuum for disposal remotely from the settling tank. It would also be desirable to provide an improved cable drive mechanism for powering the movement of the sludge collection system along the floor of a settling tank. 
       SUMMARY OF THE INVENTION 
       [0010]    It is an object of this invention to provide an improved sludge collection and removal system that overcomes the disadvantages of the prior art. 
         [0011]    It is another object of this invention to provide a sludge collector for submersed operation along the bottom of a settling tank that will collect and remove accumulated sludge with a greater efficiency than is known in the prior art. 
         [0012]    It is an advantage of this invention that sludge from the lowermost compressed zone is removed from the settling tank. 
         [0013]    It is a feature of this invention that the throat of the header wings is fully opened to enhance the collection of sludge from the compressed zone. 
         [0014]    It is another feature of this invention that the header wings are triangularly shaped with the hypotenuse thereof corresponding to the open throat of the header wing with the header wing supported on wheels and by a pivot pin connection to the drive chassis. 
         [0015]    It is another advantage of this invention that the collected sludge is consolidated at the rearward apex of the header wing to be pumped from the header wing. 
         [0016]    It is still another feature of this invention that a cable drive mechanism provides the power for movement of the sludge collection system over the floor of the settling tank. 
         [0017]    It is another object of this invention to provide a cable drive mechanism for moving the sludge collection system over the floor of a settling tank to collect and discharge sedimentation therefrom. 
         [0018]    It is yet another feature of this invention that the drive chassis is formed with spring-loaded connectors for attachment to cables that are driven by a remote winch to move the sludge collection system across the floor of the settling tank. 
         [0019]    It is still another advantage of this invention that an impact of the sludge collection system while moving along the bottom of the settling tank can be absorbed within the spring-loaded drive chassis to prevent the cable from breaking. 
         [0020]    It is yet another feature of this invention that each header wing has a pump mounted thereon at the apex of the header wing to extract the consolidated sludge from the header wing. 
         [0021]    It is still another object of this invention to provide a connector for the sludge collection mechanism that will connect two hoses running from the respective header wing pumps to combine the discharge into a single flexible hose for the removal of the collected sludge from the settling tank. 
         [0022]    It is another feature of this invention that the connector is formed with a baffle separating the two inlet ports through to the discharge port. 
         [0023]    It is yet another advantage of this invention that the baffle prevents the discharge of the pump on one header wing from overpowering the discharge from the pump on the other header wing. 
         [0024]    It is still another feature of this invention that the baffle defines a Y-valve in the T-joint interconnecting discharge hoses from the discharge pumps mounted on the header wings. 
         [0025]    It is still another advantage of this invention that the Y-valve prevents short-circuiting the vacuum applied to a header wing by the discharge pumps. 
         [0026]    It is another feature of this invention that the sludge collection system is formed with fabricated metal header wings for collecting sediment from a water settling tank. 
         [0027]    It is another advantage of this invention that the fabricated metal header wings are operable to collect sediment from the compacted Zone IV layer of sediment along the floor of the settling tank. 
         [0028]    It is still another feature of this invention that the header wings are provided with a flexible elastomeric sweep along the rearwardly converging sides of the header wings. 
         [0029]    It is yet another feature of this invention that the header wings are equipped with elastomeric sweeps attached to the rear diagonally extending sides of the header wings. 
         [0030]    It is yet another advantage of this invention that the elastomeric sweeps on the header wings help direct the Zone IV compaction layer of sediment into the apex of the header wing for extraction and removal from the settling tank. 
         [0031]    It is another feature of this invention that the sludge collection system can be coupled with settlers positioned within the settling tank to facilitate the removal of sediment from the water within the settling tank. 
         [0032]    It is still another advantage of this invention that the sludge collection system can be operated underneath the settler blocks without impeding the operation thereof. 
         [0033]    It is a further object of this invention that the process of collecting sediment from a settling tank collects the Zone IV compaction layer of sediment adjacent the floor of the settling tank. 
         [0034]    It is a feature of this invention that the skirt attached to the rear diagonally extending edges of the fabricated metal header wings sweeps the sediment from the compaction Zone IV layer along the floor of the settling tank into the apex of the header wings for removal therefrom by pumps mounted on the top of the header wings. 
         [0035]    It is another feature of this invention that the collected sludge from the compaction Zone IV layer accumulates in the apex of the header wings to fill the apex for extraction thereof from the header wing. 
         [0036]    It is an advantage of this invention that the accumulated sludge in the apex of the header wings limits the less dense sediment zones from the extraction process. 
         [0037]    It is another advantage of this invention that the accumulation of sludge within the apex of the header wings pushes the less dense sediment zones forwardly through the open throat of the header wings to be swept over top of the header wings and deposited on the floor of the settling tank rearwardly of the header wings. 
         [0038]    It is still another object of this invention to provide a submersible sludge collection system for use along the floor of a settling tank or a sedimentation basin, which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
         [0039]    These and other objects, features and advantages are accomplished according to the instant invention by providing a method of removing sediment from the bottom of a settling tank or sedimentation basin that collects the sediment from the compressed Zone IV layer of sediment adjacent the floor of the settling tank. The process utilizes a fabricated metal sludge collection system having a central truck and a pair of triangularly shaped header wings extending laterally to each side of the central truck. The header wings have an open throat that allows the passage of the Zone IV sediment layer into the header wing, while the diagonally oriented, rearwardly extending side edges of the header wing have elastomeric sweeps attached to prevent the sediment from passing out of the header wing. The sweeps accumulate the sediment at the rearwardly trailing apex of the header wing where a pump extracts the accumulated sediment remotely from the settling tank. A T-connector is formed with a baffle to improve the discharge of sediment from the header wings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]    The advantages of this invention will become apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
           [0041]      FIG. 1  is a partial perspective view of a rectangular settling tank having portions broken away to view the sludge collection system mounted along the floor of the settling tank and incorporating the principles of the instant invention; 
           [0042]      FIG. 2  is a top plan view of the settling tank shown in  FIG. 1 ; 
           [0043]      FIG. 3  is a cross-sectional view of the settling tank taken along lines  3 - 3  of  FIG. 2  to depict a front elevational view of the sludge collection system mounted along the floor of the settling tank; 
           [0044]      FIG. 4  is an exploded view of the sludge collection system incorporating the principles of the instant invention; 
           [0045]      FIG. 5  is a top plan view of the left header wing with the discharge pump being removed for purposes of clarity; 
           [0046]      FIG. 6  is a front elevational view of the shell of the header wing; 
           [0047]      FIG. 7  is a bottom plan view of the left header wing showing the roller supports supporting the header wing shell for movement along the floor of the settling tank; 
           [0048]      FIG. 8  is an enlarged perspective view of the drive unit of the cable drive mechanism corresponding to circle— 8  of  FIG. 1 ; 
           [0049]      FIG. 9  is an enlarged perspective view of the home point sheave forming part of the cable drive mechanism corresponding to circle— 9  of  FIG. 1 ; 
           [0050]      FIG. 10  is an enlarged perspective view of the return point sheave forming a part of the cable drive mechanism corresponding to circle— 10  of  FIG. 1 ; 
           [0051]      FIG. 11  is a perspective view of the truck chassis incorporating the principles of the instant invention; 
           [0052]      FIG. 12  is a top plan view of the truck chassis shown in  FIG. 11 ; 
           [0053]      FIG. 13  is a perspective view of the T-connector interconnecting the two discharge hoses from the header wing pumps with a single discharge hose, and incorporating the principles of the instant invention; 
           [0054]      FIG. 14  is a top plan view of the connector shown in  FIG. 15 ; and 
           [0055]      FIG. 15  is a schematic diagram corresponding to a cross-section through a header wing to depict the consolidation and accumulation of sediment in the apex of the header wing, arrows depicting the passing of other layers over top of the header wing. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0056]    Referring to the drawings, a sludge collection system incorporating the principles of the instant invention can best be seen. The sludge collection system  10  is mounted along the floor of a settling tank  5  which is used for settling entrained solids from a supply of water supplied to the settling tank  5  through the inlet (not shown). The velocity of the water is slowed to allow the large entrained solids to settle to the bottom surface or floor  9  of the settling tank  5 . In some circumstances, a precipitator or settler P, as is schematically depicted in  FIG. 3 , can be added to the water supply within the settling tank  5  to facilitate the precipitation of suspended solids to the bottom surface  9  of the settling tank  5 . 
         [0057]    The sludge collection system  10  is mounted for operation along the floor of a settling tank to collect and remove the sediment accumulated thereon due to the operation of the settling tank  5 . Although the drawings depict the settling tank  5  as being rectangular and being of a certain size that matches with a single pair of header wings  30  spanning from one transversely spaced wall  6  to the other vertical wall  6 , one skilled in the art will recognize that the settling tank  5  can be formed in other shapes, including a circular settling tank  5  or a rectangular settling tank  5  that has a span between the transversely opposed vertical side walls  6  that is sufficiently large as to require two or more sludge collection systems  10 , which could be independently or simultaneously operable. 
         [0058]    As best seen in  FIGS. 1-4 ,  11  and  12 , the sludge collection system  10  includes a central truck or chassis  11  that is engaged with a guide rail or track  12  mounted on the floor  9  of the settling tank  5 . Preferably, the guide rail  12  extends between a home point sheave  17  mounted on one end wall  8  of the settling tank  5  and a return point sheave  18  mounted on the opposing end wall  8 , forming part of the cable drive mechanism  15 , as will be discussed in greater detail below. The truck  11  is preferably formed with rollers or wheels  13  that facilitate the movement of the truck  11  along the bottom floor  9  of the settling tank  5 . The truck or chassis  11  is connected to the cable drive mechanism, described in greater detail below. The chassis  11  includes pre-tensioned springs  14   b  that provide a shock-absorbing capability to the connection plates  14   a  at the front and rear ends  14  of the chassis  11  for connection of the chassis  11  to the cable  19 . In operation, the pre-tensioned springs  14   b  allow the header wings  20  or the chassis  11  to impact an obstacle within the settling tank  5  without causing the cable  19  or the chassis  11  to break. 
         [0059]    The truck  11  pivotally mounts a pair of header wings  20  at the front end of the truck  11  on the respective transverse sides thereof by respective pivot pins  21   a . The header wings  20  are best seen in  FIGS. 4-7  and are formed in the shape of a triangle oriented such that the hypotenuse of the triangular shape is the front edge  21  forming the open throat of the header wing  20  and the apex  22  is located at the rear of the header wing  20 . The header wing  20  is approximately four inches high with the front edge  21  defining an open inlet throat that does not restrict the movement of sludge from the compressed zone into the header wing  20 . To facilitate the movement of the sediment along the side edges  24 , the header wings  20  are provided with rollers  26   a  that support the central and distal portions of the header wings  20  for movement over the floor  9  of the settling tank  5 . The inboard end of each header wing  20  is supported by the connection to a pivot pin  26   b  carried by the chassis  11 . With this configuration, each header wing  20  is weight-supported on the rollers  26   a  and pivot pin  26   b  to facilitate the collection of the compacted Zone IV sediment. 
         [0060]    As the header wing  20  moves forwardly along the floor  9  of the settling tank  5 , the sludge entering the open throat at the front edge  21  is consolidated toward the apex  22  by the angled sides  24  of the header wing  20 . One skilled in the art will understand that the compressed Zone IV sediment along the floor  9  of the settling tank  5  includes up to 3% solids, which allows the sediment to consolidate toward and accumulate into the apex  22  for extraction from the header wings  20  by the pumps  30 . The accumulation of the dense sediment from the compacted zone into the apex  22  pushes the less dense layers of sediment forwardly toward the front edge  21  of the header wing  20  as the header wing  20  is moving forwardly, as is depicted schematically in  FIG. 15 , to force the less dense layers of sediment out of the header wing  20  through the open throat at the front edge  21  to pass over the top of the header wing  20  and be deposited on the floor  9  rearwardly of the forwardly moving sludge collection system  10 . 
         [0061]    Preferably, the shell  26  of the header wings  20  is formed from stainless steel to provide a structure with an extended operative life requiring a minimum of maintenance. The top surface  27  of the shell  26  is generally planar, but the front portion  28  thereof terminating at the front edge  21  is preferably bent downwardly to facilitate the movement of the upper zones of sediment over the top of the shell  26  to return to the floor  9  of the settling tank  5  behind the header wings  20 . Flexible elastomeric sweeps  25 , preferably formed of rubber, are attached to the side edges  24  to help scrape the compacted Zone IV sediment off the floor, to prevent the escape of solids underneath the side edges  24 , and to help consolidate the collected sediment toward the apex  22 . Each flexible elastomeric sweep  25  is attached along the side edges  24  by a retainer  23  that is bolted to the shell  26  through the sweep  25 . Thus, the sweeps  25  can be serviced or replaced as needed. 
         [0062]    The top surface  27  of each header wing  20  is formed with an access opening  29  near the apex  22  for the extraction of the consolidated sediment accumulating at the apex  22  during the operation of the sludge collection system  10 . A pump  30  is fastened to the top surface  27  at the access opening  29  to extract the accumulated and consolidated sludge from the apex  22 . Alternatively, the access opening  29  can be utilized to connect a vacuum hose (not shown) that is connected to a remote pump to draw the accumulated sludge through the vacuum hose for removal from the settling tank  5 . A brace  22   a  extends between the apex  22  of each header wing  20  to the truck  11  to stabilize the movement of the header wings  20  with the truck  11  along the guide rail. 
         [0063]    The pump  30  is connected to a discharge conduit  32 , preferably a flexible hose that is supported along the top surface  27  to the truck  11 , although the discharge conduit  32  could be formed of a rigid conduit. Each discharge conduit  32  is connected to a respective inlet port  36  of a T-connector  35  supported on the truck  11 . The outlet port  37  of the T-connector  35  is then connected to a flexible discharge conduit  34  that is operable to convey the collected sludge to a location that is remote from the settling tank  5 . The T-connector  35  is preferably formed with an internal baffle  39  that separates the two inlet ports  36  through to the discharge port  37  so that if one of the discharge conduits  34  or the corresponding inlet port  36  becomes clogged or partially clogged, the operation of the other discharge conduit and corresponding inlet port will not be affected. 
         [0064]    As is best seen in  FIGS. 13 and 14 , each discharge port  37  of the T-connector  35  has a smaller cross-sectional area than the corresponding inlet port  36 . As a result, the movement of sediment and liquid through the discharge port  37  creates a Venturi that expands into the connection of the flexible discharge conduit  34  and thus creates a vacuum with respect to the other discharge port  37 . In the event one side of the discharge conduit  32  is plugged and becomes inoperable, the movement of sediment and water through the other discharge port  37  creates a sufficient vacuum on the other discharge port  37  that sediment will not reflux into the clogged side of the sludge collection system  10 . 
         [0065]    Preferably, the truck or chassis  11  is moved from one end wall  8  to the other end wall  8  by a cable drive mechanism  15 . Alternatively, the truck  11  could be equipped with a submersible electric or pneumatic drive mechanism that would power the movement of the sludge collection system  10  along the guide rail  12 . The cable drive mechanism  15  includes a drive unit  16 , which is preferably an electric motor  16   a , mounted above the water in the settling tank  5  to move a cable  19  in the requisite direction for moving the truck  11  connected to the cable  19 . One skilled in the art will recognize that the drive motor  16   a  can be a helical drive, or a planetary drive mechanism, and can be powered pneumatically or hydraulically, as well as electrically. 
         [0066]    A home point sheave  17 , which can be formed with pulleys or guide blocks (not shown), is mounted to the end wall  8  below the drive unit  16  to change the direction of the cable  19  from the vertical orientation descending from the drive unit  16  to a horizontal orientation to connect to the truck  11 . Similarly, a return point sheave  18  is mounted to the opposing end wall  8  to affect a return of the cable  19 , as will be described in greater detail below. The return point sheave  18  can be formed with a pulley or a guide block to cause a change in direction of the cable  19 . 
         [0067]    As is best seen in  FIGS. 1 ,  11  and  12 , the cable  19  is connected to the rear connection plate  14   a  of the truck  11  at the rear end  14  thereof and extends from the truck  11  to the home point sheave  17  to the drive unit  16 . The drive unit  16  returns the cable  19  to the home point sheave  17  through a driving engagement with the drive unit  16  to be reoriented toward the truck  11  where the cable  19  passes through the truck  11 . The cable  19  then engages the return point sheave  18  and returns direction back to the truck  11  where the cable  19  is connected to the front connection plate  14   a  of the truck  11 . In essence, the cable  19  forms an endless loop that is driven by the drive unit  16  to pull on one end  14   a  of the truck  11  to move the truck  11  forward in operation and then reverses operative direction to pull on the rearward end  14  of the truck  11  to return the truck  11  back to the home point sheave  17 . 
         [0068]    As noted above, the front and rear connection plates  14   a  are pre-tensioned by the springs  14   b  and movable relative to the corresponding end  14  of the truck chassis  11  to allow some positional flexibility in the configuration of the chassis  11  in case the sludge collection system  10  encounters a significant obstacle at the bottom of the settling tank  5 , such as a concrete block or a log, etc. The cable drive mechanism  15  incorporates a shut-down feature that ceases driving the cable  19  when a significant increase in tension in the cable  19  is encountered. The positional flexibility of the chassis  11  allows some movement in the cable drive system  15  without over-tensioning the cable  19  and causing the cable  19  to break. The front and rear ends  14  of the truck  11  are movable along the floor  9  of the settling tank  5  to push the compacted sediment in the Zone IV layer to the opposing sides of the truck  11  where the header wings receive the sediment through the open throat  21  therein. 
         [0069]    As best seen in  FIGS. 11 and 12 , the truck chassis  11  includes a pair of laterally spaced slide rails  14   c  that engage the guide rail  12  to keep the truck  11  moving along the guide rail  12  as the cable drive mechanism  15  powers the movement of the truck  11 . The front and rear ends  14  include a grommet  14   d  to allow the passage of the cable  19  through the truck  11 , as is described in greater detail above, so that the cable can extend between the home point sheave  17  and the return sheave  18  and enable the cable to be connected to both of the connection plates  14   a , passing through aligned holes  14   e  in the front and rear ends  14 , respectively, to reach the corresponding connection plate  14   a.    
         [0070]    In operation, the sludge collection system  10  is preferably manually operated by activating the drive unit  16  to cause the truck  11  and attached header wings  20  to move forwardly into the compressed zone of sediment accumulated at the bottom floor  9  of the settling tank  5 . The pumps  30  also need to be activated at the same time as the drive unit  16 . Preferably, a control panel  40  is provided at the settling tank  5  to control the electrical operation of the drive unit  16  and pumps  30 . Alternatively, the sludge collection system  10  could be automated through a microprocessor (not shown) in the control box  40  to operate the sludge collection system  10  on a timed basis. Limit switches (not shown) can be utilized to inform the control box  40  that an end wall  8  has been reached on either the operative run or on the return run. 
         [0071]    Once the drive unit  16  is activated, the sludge collection system  10  will move forwardly from the home point sheave  17  toward the return point sheave  18  pulling the sludge from the compressed zone through the open throat of each header wing  20  to be consolidated by the sweeps  25  mounted to the side edges  24  toward the apex  22  where the pump  30  extracts the consolidated and accumulated sludge from the shell  26  of the header wing  20  to pass the sludge through the discharge conduits  32 ,  34  to a location remotely from the settling tank  5 , where the discharged sludge can be treated independently. As reflected in  FIG. 15 , the accumulated sludge S fills the apex  22  of each header wing  20  to force the less dense sediment zones forwardly through the open throat at the front edge  21 , as represented by the arrows in  FIG. 15 , to pass over the bent front portion  28  and over the planar top surface  27  to be deposited on the floor  9  rearwardly of the header wings  20 . 
         [0072]    The truck  11  continues moving forwardly gathering the sludge from the compressed zone until the truck  11  reaches the return point sheave  18  at the opposing end wall  8 . At this point, a limit switch (not shown) is engaged and the drive unit  16  reverses direction to pull on the rearward end  14  of the truck  11  on a return run to reposition the sludge collection system  10  at the home position adjacent the home point sheave  17 . The front end  14  of the truck pushing the sediment along the floor  9  of the settling tank  5  to either side thereof into the adjacent header wings  20  for accumulation therein. 
         [0073]    With the extraction of the sediment from the compressed zone, the sediment in the zones above the header wings  20  move over the top of the front portion  28  and the planar top surface  27  of the shell  26  to be deposited along the floor  9  of the settling tank  5  behind the header wings  20 . Upon the return of the sludge collection system  10  to the home position next to the home point sheave  17 , the remaining sludge from the upper sediment zones is redistributed along the floor  9  of the settling tank  5 . Ultimately, with the continued operation of the settling tank  5  and the accumulation of additional sediment, the lowermost layer becomes the compressed zone, which is then subsequently collected and removed from the settling tank  5  with the operation of the sludge collection system  10 . 
         [0074]    It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention.