Patent Publication Number: US-2021162474-A1

Title: Organic matter processing apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to an organic matter processing apparatus that performs decomposition processing of organic matter, such as food waste, by a microorganism. 
     BACKGROUND ART 
     Recently, with growing concern about environmental pollution due to food waste, a variety of food waste processing methods have been studied. 
     As an example of a food waste processing technique, a food waste processing apparatus is known that accommodates porous base materials, such as sawdust and woodchips, and microorganisms in a processing tank, putting and mixing food waste in the processing tank, and performs decomposition processing on this food waste by the microorganisms (for example, refer to Patent Literature 1). 
     The food waste processing apparatus shown in Patent Literature 1 generates compost by decomposing and reducing food processing residues. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: Japanese Patent No. 3001852 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     Incidentally, although this kind of food waste processing apparatus can reduce the volume of food waste, there has been a problem that a by-product discharged from the food waste processing apparatus must be reprocessed. 
     Additionally, although the processed materials subjected to decomposition processing and discharged by the food waste processing apparatus are generally discharged to a sewer, etc., since solid matters are included in the processed materials, a problem such as clogged pipes may be caused. 
     Further, when the solid matters included in the processed materials are removed with a filter, the filter is quickly clogged, the replacement frequency of the filter is shortened, and it is difficult to maintain the filter. 
     Therefore, an object of the present invention is to provide an organic matter processing apparatus, etc. that allows easy maintenance of a filter, and does not require a processing facility for a by-product. 
     Solution to Problem 
     In order to achieve the above-described object, an organic matter processing apparatus according to claim  1  includes a processing tank ( 2 ) in which decomposition processing of organic matter is performed by a microorganism, a filter unit ( 20 ) including a filter ( 21 ) for removing solid matter included in a waste fluid generated by the decomposition processing, a reservoir ( 35 ) that stores the waste fluid from which the solid matter is removed by the filter unit, and a waste fluid circulation unit ( 40 ) that returns the waste fluid stored in the reservoir to the processing tank. 
     Additionally, the invention according to claim  2  includes, in the organic matter processing apparatus according to claim  1 , a washing unit ( 50 ) that removes the solid matter adhered to the filter to wash the filter unit. 
     Additionally, in the invention according to claim  3 , in the organic matter processing apparatus according to claim  2 , the washing unit includes a solid matter circulation unit ( 20 ,  74 ) that returns the solid matter removed from the filter to the processing tank. 
     Additionally, in the invention according to claim  4 , in the organic matter processing apparatus according to any one of claims  1  to  3 , the solid matter circulation unit sends back the waste fluid discharged from the filter unit to the filter unit. 
     Additionally, in the invention according to claim  5 , the organic matter processing apparatus according to any one of claims  1  to  4  includes a first flow channel ( 71 ) that communicates the processing tank with one end side of the filter unit, a second flow channel ( 72 ) that communicates the other end side of the filter unit with the reservoir, a third flow channel ( 73 ) that communicates the reservoir with the processing tank, a fourth flow channel ( 74 ) that communicates the one end side of the filter unit with the processing tank, valves (B 1  to B 8 ) that open or close the respective flow channels, and a control unit that controls opening and closing of each of the valves, wherein the control unit opens or closes each of the valves to open or close each of the flow channels. 
     Additionally, an organic matter processing method according to claim  6  includes a decomposition processing step of performing decomposition processing of organic matter by a microorganism in a processing tank into which the organic matter is put, a solid matter removing step of removing solid matter included in a waste fluid generated by the decomposition processing, and a waste fluid circulating step of returning the waste fluid from which the solid matter is removed to the processing tank. 
     Advantageous Effects of Invention 
     According to the present invention, since the waste fluid on which the decomposition processing has been performed by the microorganism is reused, a by-product is not generated by processing of food waste. Additionally, even in a case where disposal processing is performed on the waste fluid, since the solid matter included in the waste fluid has been removed, even when the waste fluid is discharged to the sewer, etc., pipes will not be clogged and the disposal processing is easy. 
     Further, since the filter is washed by using the waste fluid, it is possible to extend the service life of the filter, and the maintenance of the filter is easy. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram showing the external appearance of a food waste processing apparatus seen from behind. 
         FIG. 2  is a left side view showing the external appearance of the food waste processing apparatus. 
         FIG. 3  is a right side view showing the external appearance of the food waste processing apparatus. 
         FIG. 4  is a schematic diagram for describing the inside of a processing tank of the food waste processing apparatus. 
         FIG. 5  is a schematic diagram for describing the inside of a body case. 
         FIG. 6  is a schematic diagram showing a configuration example of an apparatus for stirring food waste. 
         FIG. 7  is an A-A cross-sectional view of  FIG. 6 . 
         FIG. 8  is a schematic diagram for describing the inside of a filter unit. 
         FIG. 9  is a partial enlarged view for describing the actions of a filter:  FIG. 9( a )  is a diagram describing a purification function of a waste fluid; and 
         FIG. 9( b )  is a diagram describing a removing function of solid matters adhered to the filter. 
         FIG. 10  is a schematic diagram for describing an exemplary processing operation of the waste fluid in the food waste processing apparatus. 
         FIG. 11  is a schematic diagram for describing an exemplary operation of reusing processing of the waste fluid in the food waste processing apparatus. 
         FIG. 12  is a schematic diagram for describing an exemplary operation of washing processing of the filter in the food waste processing apparatus. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     Hereinafter, examples of a fixing apparatus according to the present invention will be described with reference to the drawings. Note that the following examples do not limit the invention according to each of the claims, and not all the combinations of features described in the examples are essential to the solution of the invention. 
     (Outline of Food Waste Processing Apparatus) 
     A food waste processing apparatus S in the present embodiment is based on a microorganism decomposition processing system, includes a processing tank  2  having a predetermined space, accommodates a carrier for a microorganism (pieces of wood carrying a microorganism, etc.), not shown, and food waste in this processing tank  2 , and performs decomposition processing of this food waste by the microorganism. Additionally, the food waste processing apparatus S circulates a waste fluid generated by the decomposition processing by the microorganism, without performing disposal processing, and after removing solid matters included in the waste fluid and purifying the waste fluid, the food waste processing apparatus S returns the waste fluid to the processing tank  2 . Further, the solid matters removed from the waste fluid are also returned to the processing tank  2 , and the decomposition processing is performed on the solid matters again by the microorganism. 
     Accordingly, since the food waste processing apparatus S of the present embodiment purifies the waste fluid on which the decomposition processing has been performed by the microorganism, thereafter returns the waste fluid to the processing tank  2 , and reuses the waste fluid to perform decomposition processing of food waste, it is unnecessary to perform the disposal processing. Additionally, even if the disposal processing of the waste fluid is performed, since solid matters included in the waste fluid have been removed, it is possible to prevent pipes of the sewer, etc. from being clogged. 
     (Configuration of Food Waste Processing Apparatus) 
     As shown in  FIG. 1  to  FIG. 3 , the food waste processing apparatus S includes a processing tank  2  that performs decomposition processing of organic matter, such as food waste, by a microorganism, a filter unit  20  including a filter  21  that removes and purifies the solid matters included in the waste fluid by filtering the waste fluid that has been processed in the processing tank  2 , a storage tank  35  (a reservoir of the present application) that stores the purified waste fluid, a waste fluid circulation unit  40  that returns the waste fluid in the storage tank  35  to the processing tank  2 , and a washing unit  50  that removes the solid matters adhered to the filter  21  of the filter unit  20  to wash the filter  21 . 
     As shown in  FIG. 1  and  FIG. 4 , the processing tank  2  includes a body case  5  that functions as a first processing tank  2   a  and a second processing tank  2   b , and a subcase  10  that functions as a third processing tank  2   c  provided as a separate body from this body case  5  via a communication passage  9 . 
     As shown in  FIG. 1 , the body case  5  and the subcase  10  are placed on base  50  constituted by a plurality of square pipes, and the body case  5  is supported by a pair of left and right support bodies  51  constituted by a plurality of square pipes rising from the base  50 . Additionally, the filter unit  20  is placed on a stand  52  that is behind the body case  5  and placed on the base  50 , and the storage tank  35  is supported by the support bodies  51  on the right-hand side of the body case  5 . 
     Additionally, casters  50   a  are attached under the base  50 , and the food waste processing apparatus S can be freely moved on a floor with these casters  50   a . Note that these casters  50   a  are not essential components, and are provided when necessary. 
     As shown in  FIG. 1  and  FIG. 5 , the body case  5  is formed by metal panels, etc. into a bottomed square cylinder shape including the lower end formed into a substantially U-shape having an arc-shape in cross section so that processed matters gather in a center portion, and includes, at the upper end, an opening  5   a  that functions as an input port through which a microorganism carrier and food waste are input. 
     On the other hand, the subcase  10  functions as the third processing tank  2   c , and includes a housing having a cylindrical space that can accommodate the food waste processed in the body case  5 . This subcase  10  communicates with the body case  5  via the communication passage  9 , and is arranged under the body case  5 . 
     Additionally, as shown in  FIG. 4  and  FIG. 5 , the inside of the body case  5  is divided into the first processing tank  2   a  and the second processing tank  2   b  via a partition body  7  that partitions the inside into the top and bottom. This partition body  7  is formed by curving, for example, a metal thin plate into a shape similar to the lower end of the body case  5 , and is attached to the inside of the body case  5 . 
     Additionally, a plurality of through-holes  7   a ,  7   a  penetrating in the vertical direction are formed substantially in the vicinity of the center portion of this partition body  7 . The opening diameter of the through-hole  7   a  formed in this partition body  7  is formed to be larger than the opening diameter of the communication passage  9 , and it is preferable that food waste on which the decomposition processing has been performed by each of the processing tanks  2   a  to  2   c  is gradually subdivided. 
     Additionally, as shown in  FIG. 4 , a stirring shaft  16  is rotatably provided in the horizontal direction between the left and right side walls inside the body case  5 , and a plurality of stirring wings  17  extending in the direction perpendicular to the axial direction are provided on this stirring shaft  16  at a predetermined interval. 
     The stirring shaft  16  is supported by bearings  5   b  and  5   b  formed in the side walls of the body case  5 , and is connected to a driving motor M by a speed reduction mechanism, etc. constituted by gears, not shown, via a transmission mechanism  18  constituted by pulleys  53  and a chain  54  as shown in  FIG. 3 . This driving motor M is placed behind the subcase  10  and on the base  50 . 
     Additionally, as shown in  FIG. 6 , the stirring shaft  16  includes cylindrical ends  16   a  and  16   a  supported by the bearings  5   b  and  5   b , and a center portion whose surface is formed into a polygonal shape, not shown, and the stirring wings  17  are provided in this center portion. 
     The stirring wing  17  includes an annular connection member  17   a , which is attached to the center portion of the stirring shaft, and whose interior is formed into a polygonal shape (for example, a hexagon), a shaft  17   b  extending in one direction from this connection member  17   a , and a spatula-shaped stirring body  17 c provided at the tip of the shaft  17   b.    
     A plurality of stirring wings  17  are provided along the axial direction of the stirring shaft  16  by adjusting the interval between the adjacent stirring wings  17  with an interval adjustment member  18  whose interior is formed into a polygonal shape. 
     Additionally, as shown in  FIG. 7 , each of the stirring wings  17  is evenly arranged around the shaft. 
     Then, the stirring shaft  16  is rotated and driven at a predetermined number of rotations by the forward and reverse rotation driving of the driving motor M, by transmitting the rotation of the driving motor M through the speed reduction mechanism or a transmitter mechanism  18 . The stirring wings  17  are rotated with the rotation of this stirring shaft  16 , and stir the food waste put into the first processing tank  2   a.    
     Additionally, the tip portions of the stirring wings  17  contact the surface of the partition body  7 , and the food waste stirred by the stirring wings  17  and decomposed by the microorganism is ground between the surface of the partition body  7  to fall from the through-holes  7   a  of the partition body  7  to the second processing tank  2   b.    
     In the food waste processing apparatus S configured in this manner, the food waste subjected to the decomposition processing by the microorganism and stirred by the stirring wings  17  in the first processing tank  2   a  (hereinafter referred to as “the primary processed material”) falls to the second processing tank  2   b  via these through-holes  7   a  and  7   a  by its own weight or contact with the stirring wings  17 . Additionally, the food waste obtained by performing further decomposition processing on the primary processed material by the microorganism in the second processing tank  2   b  (hereinafter referred to as “the secondary processed material”) passes through the communication passage  9  by its own weight, and falls to the third processing tank  2   c.    
     In this manner, in the food waste processing apparatus S of the present embodiment, the food waste is decomposed by the microorganism in each of the processing tanks  2   a  to  2   c , and is gradually subdivided in the order of the first processing tank  2   a , the second processing tank  2   b , and the third processing tank  2   c.    
     Note that, in the following description, the food waste on which the decomposition processing has been performed by the microorganism in the third processing tank  2   c  is referred to as “the third processed material” for convenience. Additionally, this third processed material is specifically a liquid including solid matters, and is referred to as a “waste fluid” for convenience in the following description. 
     The filter unit  20  filters the waste fluid processed in the processing tank  2  with the filter  21  to remove the solid matters included in the waste fluid. 
     As shown in  FIG. 8 , the filter unit  20  includes a body  22  including a space inside, and the spring-type filter  21  arranged inside the body  22  and formed into a ring shape. 
     The upper and bottom ends of the filter  21  are supported by support bodies  23   a  and  23   b , and the support body  23   b  supporting the lower end of the filter  21  is provided in the bottom of the body  22 . Note that, in the filter  21  of the present embodiment, the upper end is fixed and supported by the support body  23   a , and the lower end is supported by the support body  23   b  so as to be able to move in up and down directions. 
     The inside of the body  22  is divided into a lower space  22   a  and an upper space  22   c  by one of the support bodies  23   a  supporting the upper end of the filter  21 , and through-holes  23   c  communicating the internal space  21   a  of the filter  21  with the upper space  22   c  is formed in the support body  23   a.    
     Note that, when the spring-type filter  21  sucks the waste fluid from the outside, springs are pulled inward by its pressure to narrow (eliminate) the gaps between the adjacent springs, so as to separate solid matters and allow only a liquid to pass. On the other hand, when the flow of the waste fluid is reversed from the inside to the outside, the gaps between the springs are opened with the pressure. 
     Additionally, the body  22  includes two communication ports  24  and  25  in the upper end and the lower end, one communication port  24  formed in the lower end communicates with the lower space  22   a  of the body  22 , and the other communication port  25  formed in the upper end communicates with the internal space  21   a  of the filter  21  via the upper space  22   c  of the body  22 . 
     Then, as indicated by the arrows in  FIG. 8  and  FIG. 9( a ) , the waste fluid is supplied to the lower space  22   a  of the body  22  from the one communication port  24  formed in the lower end, passes through the filter  21 , and is discharged from the other communication port  25  formed in the upper end of the body  22  after passing through the internal space  21   a  of the filter  21 , the through-holes  23   c  of the support body  23   a , and the upper space  22   c  of the body  22 . 
     In this manner, when the waste fluid passes through the filter  21 , solid matters a adhere to the outer surface of the filter  21 , the solid matters a are removed, and the waste fluid is purified. 
     Additionally, as shown in  FIG. 9( b ) , the filter unit  20  can remove the solid matters a adhered to the outer surface of the filter  21  by sending back the waste fluid from the upper space  22   c  to the one communication port  24  side. Note that the solid matters a are returned to the first processing tank  2   a  by using a fourth flow channel  74 , which will be described later. 
     Additionally, as shown in  FIG. 1 , a first flow channel  71  for communicating the third processing tank  2   c  with the one communication port  24  of the filter unit  20 , and sending the waste fluid processed in the third processing tank to the filter unit, a second flow channel  72  for communicating the other communication port  25  of the filter unit  20  with the storage tank  35 , and sending the waste fluid purified by the filter unit to the storage tank  35 , a third flow channel  73  for communicating the storage tank  35  with the body case  5 , and returning the purified waste fluid accommodated in the storage tank  35  to the first processing tank  2   a , and a fourth flow channel  74  for communicating the one communication port  24  of the filter unit  20  with the body case  5 , reversing the flow of the purified waste fluid, removing the solid matters adhered to the outer surface of the filter  21 , and returning the solid matters to the first processing tank  2   a  are provided behind the body case  5 . 
     Each of the flow channels  71  to  74  is partially connected to be shared, and valves B 1  to B 8  for opening and closing the flow channels  71  to  74  are provided in each of the flow channels  71  to  74  divided by the connected portions. Then, each of the valves B 1  to B 8  is appropriately controlled to be opened or closed, so as to open or close each of the flow channels  71  to  74  to appropriately define the path of the waste fluid. 
     By sharing each of the flow channels  71  to  74  in this manner, it is possible to simplify the flow channels  71  to  74  and to easily reduce the manufacturing cost. 
     Additionally, in the present embodiment, a pump P is provided in the first flow channel  71 , and the waste fluid flows to each of the flow channels  71  to  74  by the action of this pump P. 
     Note that the valves B 1  to B 8  of the present embodiment are manually operated, but may be constituted by electromagnetic valves, etc. In this case, it is preferable that each of the valves B 1  to B 8  is automatically controlled to be opened and closed by a control apparatus, not shown. 
     The waste fluid circulation unit  40  is constituted by the third flow channel  73 , and with the input of food waste, each of the valves B 1  to B 8  is appropriately opened and closed and the pump P is driven to return the waste fluid in the storage tank  35  into the first processing tank  2   a . This third path  73  is partially shared with the first flow channel  71 , and the pump P is arranged in this path. One end of the third flow channel  73  is attached to a lower end side wall of the storage tank  35 , and the other end is attached to an upper end of a rear side wall of the body case  5 . 
     Then, the purified waste fluid is discharged from the storage tank  35  via the third flow channel  73  by the action of the pump P, and is supplied into the case body  5 . Accordingly, since the food waste is mixed with the waste fluid put in by the waste fluid circulation unit  40 , the food waste is softened and easily subdivided by the stirring wings  17 . 
     The washing unit  50  is constituted by the filter unit  20 , which functions as a solid matter circulation unit, and the fourth flow channel  74 , each of the valves B 1  to B 8  is appropriately controlled to be opened and closed to reverse the flow of the purified waste fluid temporarily stored in the upper space  22   c  of the body  22  of the filter unit  20 , so as to remove the solid matters adhered to the surface of the filter  21 , and to return the solid matters into the first processing tank  2   a . Accordingly, since the solid matters adhered to the filter  21  are removed from the filter  21 , returned into the first processing tank  2   a , and subjected to re-decomposition processing by the microorganism, the food waste processing apparatus S of the present embodiment does not require the disposal processing of the solid matters. 
     Additionally, the washing unit  50  may further include a fifth flow channel communicating the other communication port  25  of the filter unit  20  with the storage tank  35 , and a pump P arranged in the fifth flow channel, and may reverse the flow of a predetermined flow rate of the waste fluid within the filter unit  20 . 
     Note that, in the present embodiment, the fifth flow channel is partially shared with the first to third flow channels  71  to  73 , and the pump P is arranged in this path. 
     Then, the waste fluid in the storage tank  35  is supplied to the other communication port  25  of the filter unit  20  by the action of the pump P, and the flow of the waste fluid is reversed, so as to remove the solid matters adhered to the surface of the filter  21 , and return the solid matters into the first processing tank  2   a . Accordingly, since the hydraulic pressure against the filter  21  can be easily increased, it is possible to make the solid matters adhered to the filter  21  easily removed. 
     Additionally, since the solid matters included in the purified waste fluid and the waste fluid are returned into the first processing tank  2   a , the food waste processing apparatus S of the present embodiment does not require the disposal processing of the solid matters and the waste fluid. 
     (Operation of Food Waste Processing Apparatus) 
     Next, a series of exemplary operations of the food waste processing apparatus S of the present embodiment will be described. Note that, although a description will be given by assuming that, in the food waste processing apparatus S of the present embodiment, a piece of wood carrying a microorganism and a sponge carrying a microorganism are prepared, and the piece of wood and the sponge are arranged in advance in the first to third processing tanks  2   a  to  2   c , food waste, the piece of wood, and the sponge may be put in the processing tank  2  together. 
     First, when food waste is put in, the food waste processing apparatus S drives the driving motor M to drive the stirring shaft  16  via the speed reduction mechanism and the transmission mechanism  18  and to rotate the stirring wings  17 , so as to stir the food waste in the first processing tank  2   a . On this occasion, when a waste fluid is stored in the storage tank  35 , the waste fluid is supplied to the first processing tank  2   a , but this supply operation of the waste fluid will be described later. 
     The food waste is subjected to the decomposition processing by the microorganism while being stirred by the stirring wings  17 , and moisture falls by its own weight to the second processing tank  2   b  from the through-holes  7   a  formed in the partition body  7 . On the other hand, when solid matters are subdivided to sizes that allow the solid matters to pass through the through-holes  7   a  by stirring by the stirring wings  17  and the decomposition processing by the microorganism, the solid matters are pushed out downward from the through-holes  7   a  by their own weights or while being ground between the tips of the stirring wings  17 , and fall to the second processing tank  2   b.    
     Additionally, in the second processing tank  2   b , the primary processed material is further subjected to the decomposition processing by the microorganism, and is stored until the decomposition processing is performed until a size of the primary processed material allows it to pass through the communication passage  9 . Then, the primary processed material processed in the second processing tank  2   b  is discharged by its own weight to the third processing tank  2   c  via the communication passage  9  as the secondary processed material. 
     The third processing tank  2   c  temporarily stores the third processed material (waste fluid) generated by further performing the decomposition processing on the secondary processed material by the microorganism. Note that the waste fluid subjected to the decomposition processing in the third processing tank  2   c  is subjected to the decomposition processing until the solid matters have sizes that allow the solid matters to pass through the first flow channel  71 . 
     This waste fluid is stored in the storage tank  35  after removing the solid matters included in the waste fluid with the filter  21  of the filter unit  20 , and separating the waste fluid into a liquid form. 
     Here, using  FIG. 10 , a description will be given of an exemplary operation of purifying the waste fluid stored in the third processing tank  2   c , and storing the waste fluid in the storage tank  35 . As shown in  FIG. 10 , the waste fluid processed in the third processing tank  2   c  is sent to the storage tank  35  by using the first flow channel  71  and the second flow channel  72 . 
     First, the valves B 3 , B 5 , B 6  and B 8  are operated to be closed, the valves B 1 , B 2 , and B 4  and B 7  are operated to be opened, and the pump P is operated to be driven. With this operation, the waste fluid flows through the first flow channel  71  and is supplied to the filter unit  20 . Then, in the filter unit  20 , the solid matters included in the waste fluid are removed with the filter  21  and is discharged as a purified liquid, and the discharged waste fluid flows through the second flow channel  72  and is stored in the storage tank  35 . 
     Additionally, the waste fluid stored in the storage tank  35  is returned to the first processing tank  2   a  in the case body  5 , and is reused for the decomposition processing of food waste. 
     Here, using  FIG. 11 , a description will be given of an exemplary operation of returning the waste fluid stored in the storage tank  35  to the processing tank  2 . As shown in  FIG. 11 , the waste fluid is sent to the first processing tank  2   a  in the case body  5  by using the third flow channel  73 . 
     First, the valves B 1 , B 2 , B 4  and B 7  are operated to be closed, the valves B 5 , B 6  and B 8  are operated to be opened, and the pump P is operated to be driven. With this operation, the waste fluid accommodated in the storage tank  35  flows through the third flow channel  73 , and is supplied to the first processing tank  2   a  of the case body  5 . 
     By reusing the waste fluid in this manner when performing the decomposition processing of the food waste, the microorganism can be activated. Additionally, since the solid matters can be softened by dosing of moisture, the stirring by the stirring wings  17  can be easily performed, and the decomposition processing can be accelerated. Additionally, since the liquid put into the decomposition processing of the food waste is the waste fluid, it is unnecessary to provide a new facility for supplying the liquid, and the reduction of the running cost can be achieved. 
     Additionally, the food waste processing apparatus S of the present embodiment appropriately includes a function of washing the filter unit  20 . 
     Here, an exemplary operation of washing the filter  21  of the filter unit  20  will be described by using the figures. As shown in  FIG. 8 , the waste fluid purified with the filter  21  is stored in the upper space  22   c  of the filter unit  20 , and by operating the valve B 3  to be opened, the flow of the waste fluid stored in this upper space  22   c  is reversed by its own weight, and passes through the filter  21 . 
     Then, the waste fluid contacts the solid matters adhered to the surface of the filter  21  at a predetermined hydraulic pressure, and removes the solid matters from the filter  21 . The solid matters removed from the filter  21  flow through the fourth flow channel  74 , are returned to the first processing tank  2   a  of the case body  5 , and are subjected to the re-decomposition processing. Accordingly, the food waste processing apparatus S of the present embodiment does not require the disposal processing of the solid matters. 
     Next, using  FIG. 12 , another exemplary operation of washing the filter will be described. This exemplary operation increases the hydraulic pressure so that the waste fluid contacts the filter  21 , and is performed by using the fifth flow channel in addition to the fourth flow channel  74 . 
     First, the valves B 1 , B 2 , B 5  and B 7  are operated to be closed, and the valves B 3 , B 4 , B 6  and B 8  are operated to be opened, and the pump P is operated to be driven. With this operation, the waste fluid accommodated in the storage tank  35  flows through the fifth flow channel, is supplied to the exit side of the filter unit  20 , and flows back through the filter unit  20  to pass through the filter  21 . 
     Then, the waste fluid contacts the solid matters adhered to the surface of the filter  21  at the predetermined hydraulic pressure, and removes the solid matters from the filter  21 . The solid matters removed from the filter  21  flow through the fourth flow channel  74 , are returned to the first processing tank  2   a  of the case body  5 , and are subjected to the re-decomposition processing. Accordingly, the food waste processing apparatus S of the present embodiment does not require the disposal processing of the solid matters. 
     In this manner, the food waste processing apparatus S of the present embodiment circulates again (reuses) the waste fluid subjected to the decomposition processing by the microorganism, and does not require the disposal processing of the waste fluid. Additionally, since the waste fluid is reused in the food waste processing, it is unnecessary to newly provide a supplying apparatus of water, and further, since the food waste can be easily turned into a paste and can be easily subdivided by supplying this waste fluid, the decomposition processing can be activated. Even when the capacity of the storage tank  35  is exceeded, the waste fluid can be reused since it is the purified liquid, and the disposal processing is easy since pipes of the sewer, etc. will not be clogged. 
     Additionally, since the food waste processing apparatus S can appropriately remove the solid matters adhered to the filter  21 , the filter  21  is not easily clogged, and since it is possible to extend the service life of the filter  21 , the maintenance of a filter is easy. 
     Further, since the food waste processing apparatus S performs the decomposition processing again on the solid matters included in the waste fluid subjected to the decomposition processing by the microorganism, the disposal processing of the solid matters is not required. 
     Note that the present invention is not limited to the above-described embodiment, and can be modified in various ways within a scope that does not change the gist of the present invention. For example, in the food waste processing apparatus S of the present embodiment, although the processing tank  2  is divided into the first to third processing tanks, the number of the processing tanks is not particularly limited. 
     REFERENCE SIGNS LIST 
     
         
         S food waste processing apparatus 
           2  processing tank 
           20  filter unit 
           21  filter 
           35  storage tank 
           40  waste fluid circulation unit 
           50  washing unit 
           71  first flow channel 
           72  second flow channel 
           73  third flow channel 
           74  fourth flow channel