Abstract:
A septic system is provided which receives both sewage and fat, oil, and grease (FOG) at an inlet. The inlet provides fluids to a first chamber. A treatment unit is adjacent the inlet. The treatment unit includes a unit for breaking down solids and mixing them with surrounding liquid. Hydro-jetting water and oxygen into the mixture at high or low pressures achieves oxygenation. Jets injecting an enzyme solution provide for maximum contact with the waste. Injection pressure may be selected to achieve rapid oxygenation at a high level. Optionally, the water may be heated. In another form, hot or cold water is injected at selected times. Temperature may be controlled to keep enzymes working properly. Enzymes may be directly injected and carried by liquid that is hydro-jetted into the fluids being treated.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This patent application claims priority of Provisional Patent Application 61/658,803 filed Jun. 12, 2012. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]    1. Field of the Invention 
         [0003]    The present subject matter relates to a septic system for treating both sewage and FOG (fat, oil, and grease) and a method. 
         [0004]    2. Related Art 
         [0005]    There are many forms of septic treatment systems. Normally, septic systems treat only sewage. Waste fat, oil, and grease (FOG) is diverted to a grease trap. Grease is treated separately before being transported through an outlet. Mechanical treatment may be used in some septic systems to augment chemical treatment of effluents so that they may be safely sent to a septic tile field. 
         [0006]    Septic tanks receive waste fluid such as sewage. The sewage is treated so that liquid exiting from the septic tank may be safely discharged into an underground tile field. Due to build up of solids, septic tanks must be periodically pumped out, e.g., every two or three years. Another significant effect of solids buildup is the coating of tiles in the field. After sufficient buildup, it may be necessary to dig up the tile field and provide replacement tiles. Septic tanks have not traditionally been designed to treat both sewage and grease. The standard method of treating grease is by directing grease to a grease trap. Grease is removed from the trap. The prior art apparatus does not provide for the ability to simply allow grease to enter the waste stream. 
         [0007]    U.S. Pat. No. 3,638,869 discloses a sewage comminutor installation including a generally cylindrical comminutor rotatable about a vertical axis. The housing is generally scroll-shaped to define a flow passage with progressively diminishing width. Incoming pieces of material carried with sewage are broken up. This system does not contemplate comminution of the sewage itself. There is no suggestion of combining different types of waste fluids. 
         [0008]    U.S. Pat. No. 5,540,386 discloses a wastewater treatment system and method for substantially reducing total suspended solids, biological organic discharge, and FOG contaminants. Drag lines are included in tanks for removing floating and settled contaminants. This system is a mechanical system and not a septic system. 
         [0009]    U.S. Pat. No. 5,885,950 discloses a composition for treating both sewage and grease that may flow into a septic tank. However, no particular apparatus is disclosed. 
       SUMMARY  
       [0010]    Briefly stated, in accordance with the present subject matter, a septic system is provided which receives both sewage and FOG at an inlet. An inlet provides fluids to a first chamber. A treatment unit is adjacent the inlet. The treatment unit includes a unit for breaking down solids and mixing them with surrounding liquid. Hydro-jetting water and oxygen into the mixture at high or low pressures achieves oxygenation. Jets injecting an enzyme solution provide for maximum contact with the waste. Injection pressure may be selected to achieve rapid oxygenation at a high level. Optionally, the water may be heated. In another form, hot or cold water is injected at selected times. Temperature may be controlled to keep enzymes working properly. Enzymes may be directly injected and carried by liquid that is hydro-jetted into the fluids being treated. Efficiency of waste treatment is provided reducing the amount of sludge provided and reducing the frequency of necessary pumping of the septic tank. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0011]    The present subject matter may be further understood by reference to the following description taken in connection with the following drawings: 
           [0012]      FIG. 1  is a basic diagram of a house or other structure utilizing a septic system; 
           [0013]      FIG. 2  is a perspective view, partially broken away, of a prior art septic system; 
           [0014]      FIG. 3  is a cross-sectional elevation of a septic system constructed in accordance with the present subject matter; 
           [0015]      FIG. 4  is a cross-sectional view showing in greater detail a treatment unit adjacent a septic tank inlet; 
           [0016]      FIG. 5  is a cross-sectional view showing an alternative of the embodiment of  FIG. 4 ; 
           [0017]      FIG. 6  is a cross-sectional view illustrating injection of water, oxygen, and enzymes; 
           [0018]      FIG. 7  is a cross-sectional elevation illustrating further apparatus which may be included in the present system; 
           [0019]      FIG. 8  is a cross sectional view of an embodiment in which methane gas is captured from the septic tank; 
           [0020]      FIG. 9  is an illustration of a further embodiment comprising an alternative form of treatment unit; 
           [0021]      FIG. 10  is an elevation of the septic tank with a sidewall removed in which a single motive source is provided for pumps; and 
           [0022]      FIG. 11  is a plan view of a jetter nozzle. 
       
    
    
     DETAILED DESCRIPTION  
       [0023]      FIG. 1  is a basic diagram of a structure utilizing a septic system. The structure is referred to in the present description as a house  1 , but could be virtually any structure. A soil pipe  5  is installed in the ground  8 . The soil pipe  5  conducts sewage  4  to a septic tank  10 . Septic tank  10  treats sewage  4  as described below. The sewage  4  includes waste masses  7  and grease globules  9 . The waste masses  7 , primarily comprising feces, paper, and other organic matter, are treated so that they will be emulsified or otherwise turned into liquid so that they may be transported to the leach fields  18 . Effluents  12  from the septic tank  10  flow through an effluent pipe  16  to leach fields  18 . Additionally, a pumping unit (not shown) may be provided between the septic tank  10  and leach fields  18  if the leach fields are at a higher elevation. 
         [0024]      FIG. 2  is a perspective view, partially broken away, of a prior art septic tank  10 . The septic tank  10  comprises a housing  30  containing a chamber  32 . The chamber  32  is designed to hold liquid. Common shapes for a chamber  30  include a box or cylinder. Other shapes could be used. The chamber  32  has first and second opposite end walls  34  and  36 . The chamber  32  also has upper and lower walls  38  and  40 . An inlet pipe  42  receives sewage from the soil pipe  5 . The inlet pipe  42  projects through the first wall  34  into the chamber  32 . An outlet pipe  44  carries the effluent  12  ( FIG. 1 ) from the chamber  32  to the leach fields  18 . This construction maintains a liquid level of an effluent surface  66  below the inlet pipe  40  and output pipe  44 . The chamber  32  also comprises opposite sidewalls  52  and  54 . 
         [0025]    As further described below, effluent is treated with mixing fluids to break down solids. Mixing fluids include air and water and may include enzyme solutions and bacteria. 
         [0026]    Waste enters the chamber  32  through a tee  46  communicating with the end of the inlet pipe  42 . The tee  46  has an upper, access port  48  and a lower, inlet port  50 . Waste exits from the compartment  78  through the outlet pipe  44 . A tee  58  has an upper, access port  60  and a lower, outlet port  62 . A vertical wall  70  has an opening  72  and defines compartments  76  and  78 . The compartments  76  and  78  contain the inlet pipe  42  and the outlet pipe  44  respectively. The upper wall  40  contains first and second inspection lids  90  and  92  and a clean-out lid  94 . The first inspection lid  90  is preferably in registration with the access port  48  of the tee  46 . The second inspection lid  92  is preferably in registration with the access port  60  of the tee  58 . The clean-out lid  94  may be located centrally between the first and second vertical walls  34  and  36 . 
         [0027]    Sewage enters the compartment  76  through the inlet port  50 . The liquid in the compartment  76  is referred to as black water. The liquid in the compartment  78  is called gray water. Liquid flows along a path  82  from the inlet port  50  through the opening  72  in the wall  70  into the compartment  78  and out the outlet port  62  and outlet pipe  44  to the effluent pipe  16  ( FIG. 1 ). The opening  72  may contain a filter  73  in order to prevent solids from flowing through the wall  70 . Alternatively, the wall  70  may be solid and have a height such that liquid leaches over the wall  70 . In many applications, it will not be necessary to service the filter  73  any more often then it will be necessary to pump the septic tank  10 . 
         [0028]    Sewage entering the compartment  76  contains liquids and the waste masses  7 . Many forms of treatment exist. Both surfactants and bacteria may be used. Remaining solids either float to a scum layer  84  at the effluent surface  66  or sink to the bottom of the chamber  32  to a sludge layer  86 . If these solids are not removed, they can eventually slow down or even stop the flow to the drain field. Solids could also plug the inlet pipe  40  or the outlet pipe  44 . This can lead to disastrous, unpleasant, and expensive consequences. Therefore, it is conventional to remove the solids by pumping out the septic system every two to three years. 
         [0029]      FIG. 3  is a partial cross-sectional elevation of a septic tank  10  constructed in accordance with the present subject matter. In  FIG. 3 , the same reference numerals are used to denote components corresponding to those of  FIG. 2 . In the embodiment of  FIG. 3 , a treatment unit  100  is positioned adjacent the input port  50 . The treatment unit  100 , further described with respect to  FIG. 4 , is constructed to improve efficiency and effectiveness of both physical and chemical aspects of the waste treatment process. The treatment unit  100  is coupled to a chemical treatment source  118  and a source of fluid pressure  120 , preferably air, for improved mixing. The treatment source  118  and a source of pressure  120  are each further described with respect to  FIG. 4 . Consequently, the septic tank  10  may require pumping much less frequently than every two or three years. 
         [0030]      FIG. 4  is a cross-sectional view showing the treatment unit  100  in greater detail. The treatment unit  100  comprises a main support  102 . The main support  102  may comprise a vertically disposed shaft  106 . A hydro jet  104  is provided projecting downwardly and coaxially from the shaft  106 . The main support  102  is supported at an upper end in a collar  108 . The collar  108  may be disposed in the inspection lid  90 . The main support  102  may enclose conduits, e.g., first and second conduits  114  and  116 . The first and second conduits  114  and  116  may be connected to first and second supply lines  118  and  120  respectively. An air reservoir  122  provides air flow through the first supply line  118  to the first conduit  114 . The air reservoir  122  is pressurized by a compressor  124 . A fluid path is connected from the first conduit  114  to the hydro jet  104 . The hydro jet  104  contains output nozzles  130 . A third supply line  132  provides water to the treatment unit  100 . A hot and cold water supply  136  having a mixing valve  138  may supply water that is hot, cold, or mixed to the supply line. The supply line  132  in one form may be connected to supply power to rotate the blades  142  and  144 . 
         [0031]    The main support  102  also supports a breaking unit  140  supported preferably just below the liquid surface  66 . The breaking unit breaks up solids entering the compartment  76 . Many different forms of breaking unit  140  may be provided, depending on the degree of breaking desired and the cost of components. In the present embodiment, the breaking unit  140  comprises first and second blades  142  and  144 . These can break up solid masses  7 . The first and second blades  142  and  144  in the present illustration are counter-rotating. This is preferable in terms of effectiveness of comminution. Also counter rotating blades cancel force moments applied to the main support  104 . A gear unit  145 , for example, a pinion gear unit, may be connected between the first and second blades  142  and  144 . The first blade  142  is driven directly. The second blade  142  is driven in an opposite direction through the gear unit  145 . However, this is not essential. The compressor  124  may provide power to rotate the first and second blades  142  and  144 . The blades  142  and  144  may also be provided with nozzles  146  through which air, water, and/or chemical compounds may be dispensed. A jet ring  150  having outlet nozzles  152  is coupled to the second conduit  116  to provide enzyme solution. The jet ring  150  is located axially intermediate the breaking unit  140  and the collar  108 . 
         [0032]    The breaking unit  140  further comprises a shaft  147  ( FIG. 3 ) also mounted for rotation. A mixing blade  148  rotates with the shaft  147 . The mixing desk  148  preferably comprises outlet nozzles  149 . The mixing blade  148  is positioned so that it will be in the sludge layer  86 . The conduits  114 ,  116 , and  132  may be each coupled to the mixing blade  148 . All of the outlet nozzles may be connected to one conduit. Alternatively, each nozzle  149  may be connected to one selected conduit. The mixing blade  148  may also be used to dispense enzymes, air, and/or water. Other agitation means may also be provided. For example, jets  163  ( FIG. 3 ) may be built into one or more walls of the housing  34  and coupled to sources of materials to be dispensed. Any of the jets described above could also be connected to a booster pump. 
         [0033]    The mixing blade  148  comprises means for agitating the sludge layer  86 . Agitation helps keep particles of the sludge layer  86  in suspension. Therefore, the particles will have greater surface contact with treating agents. The agitation means need not be a blade. In one nominal embodiment, the mixing blade  148  should rotate slowly. In this context, slowly may be under 100 RPM. 
         [0034]      FIG. 5  is an illustration of an alternative embodiment to that of  FIG. 4 . The same reference numerals are used to denote elements corresponding to those of  FIG. 4 . The treatment unit  100  comprises a comminutor  170  comprising rotating discs  172  with grinding surfaces  174 . The grinding surfaces  174  could comprise, for example, tungsten carbide. Tungsten carbide will pulverize most solids, and will be able to break up modules of soil or grease so as to form a suspension. This embodiment may be used in applications in which the sewage  4  will include such items as animal bones. 
         [0035]    The embodiment of  FIG. 5  has a treatment lid  160  received in the upper wall  38 . The treatment lid  160  is provided so that the treatment means of the apparatus is separate from those components utilized during conventional septic tank operations. The main support  102  is received in a collar  162  in the treatment lid  160 . 
         [0036]      FIG. 6  is a partial cross-sectional view illustrating injection of water, oxygen, and enzymes. The counter-rotating blades  104  are in the waste stream entering the chamber  32 . Waste masses  7  and grease globules  9  ( FIG. 1 ) flow between the first and second blades  142  and  144 . The waste masses  7  are intercepted by the first and second blades  142  and  144  and are broken down. Pressure in the flow also breaks the masses  7  down. The nozzles  130  of the hydro jet  104  provide bubbles of air to assist the waste masses  7  to mix with liquid in the chamber  32  and to move toward the blades  104 . The supply of air from the supply  122  may be continuous, or it may be selectively enabled by a timer  192  ( FIG. 7 ). The jets  152  spray enzyme solution into the chamber  32  over the treatment unit  100 . The bubbles emerging from the hydro jets  104  create turbulence to maximize contact of the treatment enzymes with the waste masses  7 . This leads to faster and more complete liquefaction of the waste masses  7 . 
         [0037]      FIG. 7  illustrates a septic tank  10  with still further additional features. An electrical conduit  180  is provided to power a heating element  182  at the bottom of the compartment  76 . The heating element  182  may include a thermostat  184 . Other heating elements could be included. For example, a heating element  183  could be included in any of the walls of the housing  34 . 
         [0038]    The heating element  182  may heat the liquid to a preselected level. In one form, the thermostat  184  is set to heat the liquid to a level 10° higher than the temperature at the inlet port  50  as sensed by a temperature sensor  186  providing an output to the thermostat  184 . The amount of energy required to heat the liquid to a given level depends upon the difference between ambient temperature and the desired temperature. The heaters may be designed to provide, for example, a 15° F. increase in temperature. In one nominal embodiment, a preferred temperature level is 85° F. 
         [0039]    In another form, the heating element  182  may comprise a plastic body which acts as a heat reservoir. This plastic has a chemical property which provides a temperature increase of 10-12° F. over ambient water temperature. 
         [0040]    A pressure meter  190  may be provided on the air line  124 , and a pressure controller  192  may be coupled to the air line  124 . Control of the air pressure in the air line  124  will control velocity of air exiting the hydro jets  104  in the treatment unit  100 . A timer  194  may energize the enzyme solution and the air pressure source automatically. Different operating cycles may be provided. In one form, the breaking unit  140  and agitation means, the mixing blade  148  ( FIG. 6 ), are energized for 10 minutes each hour. Other schedules could be provided depending on the amount and type of sewage entering the septic tank  10 . 
         [0041]    Energy could be provided from an electric power line  200 . Additionally or alternatively, a solar unit  220  may be used to provide power. Additionally, houses with well water systems may have a need for additional treatment while using less fresh water. A pump  240  may be used to provide gray water from the compartment  78  in order to supply water sources directed into the compartment  76 . An in-line filter  250  may be used to take solids out of gray water. 
         [0042]      FIG. 8  discloses an embodiment in which methane gas is captured from the septic tank and used to produce electricity or other form of energy. Even human waste will supply sufficient methane gas to supplement power. The use of methane gas may be provided for residential, commercial, and industrial use. In the case of a farm application, the septic tank at least in part replaces cisterns into which cow manure is placed. According to the United States Department of Agriculture, different types of cows may produce 60-150 pounds of manure a day. In the septic tank, the cow manure produces sufficient methane gas to produce power in an industrial context. 
         [0043]    The septic tank  10  further comprises a biogas collector  300  coupled by a gas conduit  304  through the upper surface of the septic tank  10  to a position above ground. The conduit  304  is coupled to a methane gas reservoir  310 . The methane gas may be coupled to a gas turbine  314  that drives a gas turbo generator  316 . A pressure regulator  320  regulates input pressure to a pressure usable by the gas turbine  314 . A fluid switch  324  also provides for diversion of methane gas via a conduit  328 . The fluid switch  324  may be positioned to direct methane gas to the turbine  314  or the methane tank  330 , or to both. Additionally, the fluid switch  324  may be closed, with methane gas being stored in the methane gas reservoir  310 . 
         [0044]      FIG. 9  is an illustration of a further embodiment comprising a treatment unit  400 . The treatment unit  400  is an alternative to the treatment unit  100  described with respect to  FIGS. 3 ,  4 , and  5  above.  FIG. 9  is an elevation of the septic tank  10  with the wall  52  removed. The treatment unit  400  comprises a central driveshaft  402 , which extends through a journal bearing  404  in the top wall  38  of the septic tank  10 . Extending from the central driveshaft  402  is a rotating sprayer support shaft  410 . A lower end of the rotating sprayer support shaft  410  is received in a thrust bearing  414  at the bottom wall  40  of the septic tank  10 . The rotating sprayer support shaft  410  includes conduits similar to those in the treatment unit  100 . A first, upper sprayer  430  is mounted to the rotating sprayer support shaft  410 . The upper sprayer  430  preferably comprises a cylinder  432  with sprayer holes  434 . In one preferred embodiment, the upper sprayer  430  is perpendicular to the rotating sprayer support shaft  410  in both horizontal and vertical degrees of freedom. However, this is not necessary. Similarly, a lower rotating sprayer  450  is mounted in a vertical position calculated to be above the sludge layer  86  ( FIG. 7 ). 
         [0045]    The central driveshaft  402  is rotated by a gear assembly  460  driven by a motor  466 . A central shaft drive rod  468  coupled to the motor  466  drives the gear assembly  460 . 
         [0046]    In accordance with a further feature of the present subject matter, the single motor  466  is used to drive the central driveshaft  402  as well as a water pump  470  and an air pump  476 . The water pump  470  is driven by the motor  466  via a water pump gear assembly  472 . The air pump  476  is driven by the motor  466  via an air pump gear assembly  478 . Pulley assemblies may be used in place of gear assemblies, with the motor  466  being coupled to drive the water pump  470  and the air pump  476  by drive belts. In another form, the motor  466  may be replaced by a hand crank assembly  480 . The hand crank assembly could also be used in conjunction with the motor  466  for such functions as moving rotating parts should a power failure occur. 
         [0047]      FIG. 10  is an elevation of the septic tank with the sidewall  52  removed. An embodiment is illustrated in which a jetter  500  is mounted above ground. A driveshaft  510  extends to the upper wall  36  of the septic tank  10 . The same gear assemblies and water and air pumps may be provided as in the embodiment of  FIG. 9 . In this embodiment, the treatment unit  100  is utilized. The upper and lower sprayers  162  and  150  are replaced by upper and lower jetter nozzles  516  and  518  respectively. The upper and lower jetter nozzles  516  and  518  are rotatably mounted to a central shaft  520  ( FIG. 10 ). 
         [0048]    The upper and lower jetter nozzles  516  and  518  are mounted for rotation as further seen with respect to  FIG. 11 .  FIG. 11  is a plan view of the jetter nozzle  516 , and also illustrates the jetter nozzle  518  ( FIG. 10 ). Each jetter nozzle  516  and  518  has a plurality of outlet holes  522 . The holes  522  are tilted in the vertical and/or horizontal degree of freedom in order to create a force moment about the central shaft  520 . A central bearing  524  permits rotation of the upper and lower jetter nozzles  516  and  518  with respect to the central shaft  520 . 
         [0049]    Additionally, in  FIG. 10  a coupling conduit  540  is provided communicating with the chamber  32  ( FIG. 2 ). The coupling conduit  540  may be used for selected purposes including adding enzyme solutions from above ground, monitoring sampled or evolved fluids, and transmission of gathered methane gas. 
         [0050]    The method comprised in the present subject matter comprises directing sewage entering a septic tank toward a breaking unit. The breaking unit reduces the size of solids and globules of fluids immiscible in water. The sewage is treated with selected combinations of water, treatment chemicals, and air to maximize contact of sewage with treatment substances and increase the liquefaction of sewage and to reduce accumulation in scum and sludge layers. Treatment may be continuous or timed. Heating or other energy input may be provided. 
         [0051]    Many other modifications may be made in accordance with the above teachings. Enzymes, air, and other treatment substances may be injected into the compartment  76  or even the compartment  78 . Heaters may be located anywhere. An important consideration is maximizing the contact of treatable solids with the treatment substances. In this manner, build up of the sludge layer is minimized, and frequency of required septic tank pumping is minimized. 
         [0052]    While the foregoing written description of the subject matter enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The subject matter should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the subject matter as claimed.