Patent Publication Number: US-2006011537-A1

Title: Septic tank free from dung-sucking operation

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention is related to a septic tank having a funnel-shaped tapered bottom inside the septic tank. The septic tank further includes an internal discharge pipe with a small diameter. A lower end of the discharge pipe is an intake end adjacent to and spaced from a bottommost section of the tapered bottom by a small gap. The excreta entering the septic tank can be easily siphoned into the discharge pipe and discharged out from an outlet without solidifying and tarrying on the bottom of the septic tank. Therefore, it is unnecessary to periodically suck the excreta out of the septic tank by external force.  
      2. Description of the Prior Art  
       FIG. 1  shows an existent septic tank having two to four tank bodies communicating with each other. An upper end of the corroding tank  11  is connected to a toilet  13  via an excreta-discharging pipe  12 . The excreta are discharged into the tank  11  where the solid materials are precipitated and decomposed by anaerobes. After processed, the dirty water infiltrates into the next filtering tank  14  for filtering off the impurities. Then the dirty water flows into the oxidizing tank  15  where the organic matters entrained by the water are decomposed by aerobes into water suitable for discharge. Finally, the water flows into the draining tank  16  to be discharged from an outlet thereof into a gutter or a sewer.  
      By means of the above septic tank as shown in  FIG. 1 , through the procedures of precipitation, corrosion, filtering and oxidization, the excreta are processed into wastewater up to the discharge standard. However, the solid excreta have accumulated in the corroding tank for a long time. Therefore, after a period of use, it is necessary to use a dung-cart to suck out the excreta for keeping normal function of the corroding tank. Currently, anaerobes and aerobes are added into the septic tank to reduce the accumulating excreta and odors. However, such measure can simply prolong the period between regular sucking of the excreta, while failing to avoid accumulation of the excreta. Therefore, only the odors are reduced. The shortcoming of the above conventional septic tank is that the septic tank has a plane bottom so that the solid materials precipitating onto the bottom can be hardly entrained by dirty water to the final discharge pipe. Therefore, it is tried by the applicant to provide a measure for preventing the solid materials from tarrying in the corroding tank  11  of the septic tank.  
     SUMMARY OF THE INVENTION  
      It is therefore a primary object of the present invention to provide a septic tank free from dung-sucking operation. The septic tank has a funnel-shaped tapered bottom inside the septic tank. The tapered bottom has a conicity not larger than 90 degrees. Accordingly, a slope is formed on the bottom of the septic tank, whereby the corroded and precipitated excreta can easily quickly roll or slide to the bottommost section of the septic tank. The septic tank further includes an internal discharge pipe with a small diameter within 6˜8 cm. A lower intake end of the discharge pipe is adjacent to and spaced from a bottommost section of the tapered bottom by a small gap. By means of the small gap and the fine diameter of the discharge pipe, the corroded excreta flowing to the tapered bottom can be easily taken into the discharge pipe and further decomposed and oxidized therein. When the accumulating materials in the discharge pipe reach the height of the discharge end of the discharge pipe, the materials will spill out of the outlet of the tank into a sewer.  
      By means of the tapered bottom of the septic tank, the decomposed and precipitated excreta will quickly move to the bottom and gather in the bottommost section of the septic tank. The intake end of the discharge pipe is adjacent to the bottommost section so that the excreta and liquid successively entering the septic tank can further push the excreta into the discharge pipe. In addition, in condition that the excreta can be successfully discharged, the diameter of the discharge pipe is narrowed. Therefore, the excreta entering the septic tank can be easily siphoned into the discharge pipe and discharged out from an outlet without solidifying and tarrying on the bottom of the septic tank. Therefore, it is unnecessary to periodically suck the excreta out of the septic tank. In addition, the septic tank has one single tank body to save space.  
      The present invention can be best understood through the following description and accompanying drawings wherein: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a sectional view of a conventional septic tank;  
       FIG. 2  is a sectional view of the septic tank of the present invention;  
       FIG. 3  is a top view of an embodiment of the present invention, in which the septic tank is a cylindrical tank;  
       FIG. 4  is a top view of another embodiment of the present invention, in which the septic tank is a rectangular parallelepiped tank;  
       FIG. 5  is an enlarged view of a part of the septic tank of  FIG. 2 ; and  
       FIG. 6  is a sectional view of the septic tank of the present invention, in which a filtering screen is additionally mounted in the tank body. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Please refer to  FIG. 2 . The septic tank  2  of the present invention has an inlet  21  and an outlet  22 . The inlet  21  is connected with the excreta-discharging pipe  12  for conducting the excreta from the toilet  13  into the tank. The septic tank  2  has a funnel-shaped tapered bottom  23 . The tapered bottom  23  is inclined downward toward the center of the septic tank  2 . A discharge pipe  24  is arranged in the septic tank  2 . The discharge pipe  24  has a vertical section, a horizontal section and a bight section  241  integrally interconnected between the vertical and horizontal sections. The vertical section of the discharge pipe  24  vertically upward extends from the bottommost section of the tapered bottom  23  to the bight section  241 . The horizontal section horizontally extends from the bight section  241  to the outlet  22  of the septic tank  2 . A discharge end  242  of the discharge pipe  24  is connected with the outlet  22  of the septic tank  2 .  
       FIGS. 3 and 4  are top views of the septic tank of the present invention. The septic tank can be a cylindrical tank  2  as shown in  FIG. 3  or a rectangular parallelepiped tank  2 ′ as shown in  FIG. 4 . Alternatively, the septic tank can have any other shape adapted to the configuration of the working site. The discharge pipe  24  can be positioned at the center of the septic tank  2  or any other position as necessary. A lower end of the discharge pipe  24  is an intake end  243 . As shown in  FIG. 5 , the intake end  243  is spaced from the bottommost section  230  of the tapered bottom  23  by a gap  231 . The outer circumference of the intake end  243  is spaced from the sidewall of the tapered bottom  23  by a gap  232 . The gaps  231 ,  232  serve as narrow paths for speeding the flow of the excreta. The gaps  231 ,  232  should not be too large to lose their function. However, the gaps  231 ,  232  also should not be too narrow to jam the excreta. The optimal width of the gaps  231 ,  232  is within 2˜4 cm.  
      Referring to  FIGS. 2 and 5 , in normal state, water is fully reserved in the septic tank  2 . The water level is flush with the discharge end  242 . In order to make the excreta quickly move from the tapered bottom  23  to the intake end  243  of the discharge pipe  24 , the conicity of the tapered bottom preferably should not exceed 90 degrees. The conicity is preferably within 50˜60 degrees. Accordingly, after the excreta  3  entering the septic tank  2  are corroded and precipitated, the excreta  3  will not accumulate in the tank. Instead, the excreta  3  will quickly move along the tapered bottom  23  to a position under the intake end  243  of the discharge pipe  24 . When squeezed by the successive precipitants, the excreta  3  will get into the discharge pipe  24 . The discharge pipe  24  has a diameter within 6˜8 cm. By means of the balance of the liquid pressures inside and outside the discharge pipe  24 , the excreta  3  entering the discharge pipe  24  are sucked without downward dropping. Therefore, the excreta  3  can be further corroded, filtered and oxidized in the discharge pipe  24 . When the accumulating materials in the discharge pipe  24  ascend and reach the height of the discharge end  242 , the processed liquid will automatically spill out of the outlet  22  of the tank into the sewer.  
      In order to enhance the purifying capability of the septic tank  2 , a bactericidal unit such as ultraviolet optic contact enzyme can be arranged at the outlet  22 . In addition, in the embodiment of  FIG. 2 , the excreta-discharging pipe  12  goes into the tank body from the top thereof. According to such arrangement, the marsh gas in the tank may flow through the excreta-discharging pipe  12  and the toilet  13  back into the room. This will lead to stink. Therefore, a ventiduct  25  can be arranged on upper side of the septic tank  2  for exhausting the tank. Alternatively, the excreta-discharging pipe  12  can be arranged on a lateral side of the tank body.  
      Referring to  FIG. 6 , a filtering screen  26  can be additionally mounted in the septic tank  2 . Numerous screen orifices  27  are distributed over the filtering screen  26 . The diameter of the screen orifices  27  is relatively small for keeping the not corroded excreta on upper side of the filtering screen  26 . Only the corroded excreta can pass through the screen orifices  27  of the filtering screen  26  and drop to the bottom of the septic tank  2 . The not yet corroded excreta remaining on the upper side of the filtering screen  26  are further corroded and decomposed up to the excreta discharge standard regulated by environment protection authority. Then with the flush, the excreta are flushed to the bottom of the septic tank  2 . The corroded excreta then are taken into the discharge pipe  24 . Finally, when the corroded excreta accumulating in the discharge pipe  24  reach the discharge height, the excreta are discharged from the outlet  22  of the septic tank  2  into the sewer.  
      The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without departing from the spirit of the present invention.