JP2010207762A - Membrane type methane fermentation treatment apparatus and method for methane fermentation treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a membrane type methane fermentation treatment apparatus, in which agitation can be continued in a methane fermentation tank even during maintenance or the like of a membrane separation means, and a gas supply means can be prevented from being damaged. <P>SOLUTION: The apparatus includes: a membrane separation tank 14 provided with a membrane separation means 18 integrated therein; circulation pipes 15, 16 for circulating digested sludge between a methane fermentation tank 12 and the membrane separation tank 14; a gas diffusion means 19 for diffusing a biogas in the methane fermentation tank 12 from the bottom side of the membrane separation means 18; a discharge means 23 for discharging the biogas from a discharge port 22 opened in the digested sludge in the methane fermentation tank 12; a common blower unit 24 for supplying the biogas to the gas diffusion means 19 and the discharge means 23; and a switching means 25 for switching between a diffusion state, where the biogas supplied by the blower unit 24 is diffused from the gas diffusion means 19, and a discharge state, where the biogas is discharged from the discharge means 23. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a membrane-type methane fermentation treatment apparatus for treating organic substances such as human waste, septic tank sludge, sewage sludge, garbage, and food waste by methane fermentation, and a methane fermentation treatment using the membrane-type methane fermentation treatment apparatus. Regarding the method.

  Conventionally, as this type of membrane-type methane fermentation treatment apparatus, as shown in FIG. 10, an external circulation flow path 62 communicating with a lower region and an upper region of a tank is provided in a methane fermentation tank 61, and an external circulation flow is provided. The channel 62 includes a membrane separation tank 67, a submerged membrane separation device 63 provided in the membrane separation tank 67, and an air diffuser that is provided in the membrane separation tank 67 and diffuses from below the membrane separation apparatus 63. A device 64 is provided. In addition, a gas supply channel 65 that supplies biogas generated in the methane fermentation tank 61 to the diffuser 64 is provided, and a blower 66 is provided in the gas supply channel 65.

  According to this, a raw material is supplied to the methane fermentation tank 61 and methane fermentation is carried out in the methane fermentation tank 61. At this time, biogas is generated in the methane fermentation tank 61 in the fermentation process, the blower 66 is driven, and the biogas in the methane fermentation tank 61 is supplied from the gas supply channel 65 to the aeration device 64. As a result, biogas is diffused from the diffuser 64 and an upward flow is generated by the air lift action, and the digested sludge in the methane fermentation tank 61 circulates in the external circulation flow path 62 using this upward flow as a driving flow. Therefore, the digested sludge in the methane fermentation tank 61 is agitated. At the same time, since the upward flow is a sweeping flow and flows in the flow path between the membranes of the membrane separation device 63 in a cross flow, the membrane surface of the membrane separation device 63 is washed by the upward flow.

  The digested sludge that has flowed from the methane fermentation tank 61 into the external circulation flow path 62 is sucked and solid-liquid separated by the membrane separation device 63, and the permeate is taken out of the system from the membrane separation device 63. Thereby, the digested sludge in the methane fermentation tank 61 can be maintained at a high concentration, and a highly efficient methane fermentation process is possible.

  In this way, by the aeration from the aeration device 64, the digested sludge in the methane fermentation tank 61 and the membrane surface cleaning of the membrane separation device 63 can both be performed, and the membrane type methane having such a configuration. The fermentation treatment apparatus is described in Patent Document 1 below.

  In addition to the type shown in FIG. 10, a membrane separation tank is provided in the external circulation channel, and the digested sludge is forcibly circulated between the methane fermentation tank and the membrane separation tank by a pump or the like. There is something. In such a type, the upward flow generated by the diffusion of the biogas from the diffuser disposed below the membrane separator contributes to the membrane surface cleaning and the circulation of the digested sludge in the membrane separator. .

  Patent Document 2 listed below describes a membrane-type methane fermentation treatment apparatus that uses a pump to circulate digested sludge between a methane fermentation tank and a membrane separation tank.

JP 2001-170631 A JP-A-11-147098

  However, in the above conventional type, when the suction of digested sludge by the membrane separation device 63 is stopped for the purpose of maintenance such as inspection, replacement, and cleaning, it is necessary to stop the air diffuser 64 and the blower 66. Biogas has a temperature in the range of about 35 to 60 ° C. and humidity is saturated. For this reason, if the temperature of the blower 66 decreases as the blower 66 stops, dew condensation occurs in the blower 66, and the blower 66 is damaged together with a corrosive gas such as hydrogen sulfide contained in the biogas. There is a problem that it is difficult to restart the blower 66.

  Further, when the membrane separation device 63 becomes large, the blower 66 also becomes large along with this. Therefore, if the blower 66 is frequently started and stopped, the blower 66 is easily worn out, and the frequency of maintenance of the blower 66 and the like. There is also a problem that increases.

  Furthermore, when the sediment in the membrane separation tank 67 settles and accumulates at the bottom of the membrane separation tank 67 and the height of the sediment exceeds the aeration device 64, the aeration is biased and is not stable, and the membrane separation device. There is a problem that the film surface cleaning 63 becomes non-uniform.

  The present invention can continue stirring in the methane fermenter even when performing maintenance on the membrane separation means, etc., and can prevent damage to the gas supply means. An object of the present invention is to provide a membrane-type methane fermentation treatment apparatus and a methane fermentation treatment method capable of performing the above.

In order to achieve the above object, the first invention comprises a methane fermentation tank for performing methane fermentation of an organic substance in digested sludge, and a submerged membrane separation means for concentrating solids in the digested sludge. Membrane separation tank, a circulation channel for circulating digested sludge between the methane fermentation tank and the membrane separation tank, and a biogas produced in the methane fermentation tank and provided in the membrane separation tank A membrane-type methane fermentation treatment apparatus having an aeration means for aeration from below,
A discharge means for discharging biogas from a discharge port opened in the digested sludge in the methane fermentation tank;
A common gas supply means for supplying biogas to the aeration means and the discharge means;
Switching means capable of switching between a diffused state where the biogas supplied by the gas supply means is diffused from the diffuser means into the membrane separation tank and a discharge state where the biogas is discharged from the discharge means into the methane fermentation tank; Is provided.

  According to this, when the digested sludge is solid-liquid separated by the membrane separation means, the biogas generated in the methane fermentation tank is removed from the aeration means by driving the gas supply means and switching to the aeration state by the switching means. Aerated in the membrane separation tank. Thereby, the digested sludge in the methane fermentation tank circulates between the methane fermentation tank and the membrane separation tank through the circulation channel, and the digested sludge in the methane fermentation tank is stirred, and the membrane surface of the membrane separation means The digested sludge flowing into the membrane separation tank from the methane fermentation tank is solid-liquid separated by the membrane separation means.

  In addition, when the solid-liquid separation by the membrane separation means is stopped for the purpose of maintenance, etc., the gas supply means is continuously driven without being stopped, and is switched to the discharge state by the switching means. The produced biogas is discharged from the discharge port of the discharge means into the digested sludge in the methane fermentation tank. Thereby, the aeration from an aeration means stops, the stirring flow by an air lift effect | action generate | occur | produces in a methane fermentation tank, and the digested sludge in a methane fermentation tank is continuously stirred by this stirring flow.

  In this way, while the gas supply means is driven, the gas supply means can be stopped and the inside of the methane fermentation tank can be stirred, so that the gas supply means can be driven even when maintaining the membrane separation means. There is no need to stop. Therefore, stirring in the methane fermentation tank can be continued and temperature drop of the gas supply means can be prevented, so that condensation is generated in the gas supply means and the gas supply means is prevented from being damaged. be able to.

  Further, while the solid-liquid separation is stopped, no upward flow is generated in the membrane separation tank, and the membrane surface of the membrane separation means is not exposed to the upward flow. Thereby, it is possible to reduce damage to the membrane while maintaining stirring in the methane fermentation tank, and it is not necessary to frequently stop and start the gas supply means, and suppress wear of the gas supply means. Can do.

In the membrane type methane fermentation treatment apparatus according to the second aspect of the present invention, the aeration means and the discharge means are branched from the gas supply means.
In the membrane type methane fermentation treatment apparatus according to the third invention, the discharge means has a sediment transfer means for sucking the sediment in the membrane separation tank from the suction hole and transferring it to the outside of the membrane separation tank,
The sediment transfer means is arranged below the aeration means,
The discharge port is located downstream via the sediment transfer means,
The head pressure in the methane fermentation tank acting on the discharge port is configured to be lower than the head pressure in the membrane separation tank acting on the sediment transfer means.

  According to this, when the digested sludge is not solid-liquid separated by the membrane separation means, the biogas generated in the methane fermenter can be obtained by switching to the discharge state by the switching means while continuously driving the gas supply means. The discharged sludge is discharged from the discharge port into the digested sludge in the methane fermentation tank, and the digested sludge in the methane fermenter is continuously stirred.

  At this time, the sediment transfer means removes the sediment in the membrane separation tank from the suction holes by the head pressure difference between the suction hole of the sediment transfer means and the discharge port of the discharge means and the suction action caused by the flow of biogas. Suction and transfer out of the membrane separation tank. Thereby, the quantity of the sediment which settles and accumulates in the bottom part in a membrane separation tank can be reduced, and it can prevent that the height of a sediment exceeds an aeration means. Therefore, when air is diffused from the air diffuser by switching from the discharge state to the air diffuser, the air diffuser becomes stable and the membrane surface of the membrane separator can be cleaned uniformly.

In the membrane-type methane fermentation treatment apparatus according to the fourth invention, the discharge port is located on the downstream side via the air diffusion means,
The head pressure in the methane fermentation tank acting on the discharge port is configured to be lower than the head pressure in the membrane separation tank acting on the aeration means.

  According to this, when the digested sludge is solid-liquid separated by the membrane separation means, the biogas generated in the methane fermentation tank is removed from the aeration means by driving the gas supply means and switching to the aeration state by the switching means. Aerated in the membrane separation tank.

  If the digested sludge is not solid-liquid separated by the membrane separation means, the biogas generated in the methane fermentation tank is diffused by switching to the discharge state with the switching means while continuously driving the gas supply means. It is discharged from the discharge port into the digested sludge in the methane fermentation tank via the means.

  At this time, since the head pressure in the methane fermentation tank acting on the discharge port is lower than the head pressure in the membrane separation tank acting on the air diffuser, the biogas is not diffused from the air diffuser, and the discharge port It is discharged from. Also, the digested sludge in the membrane separation tank is removed from the air holes formed in the air diffuser by the head pressure difference between the discharge port and the air diffuser and the suction action caused by the flow of biogas flowing in the air diffuser. It can also be sucked and discharged together with biogas into the digested sludge in the methane fermentation tank from the discharge port.

In the membrane-type methane fermentation treatment apparatus according to the fifth aspect of the present invention, in the diffused state, an upward flow is generated in the membrane separation tank by the biogas diffused from the diffuser means, and this upward flow is used as a driving flow for methane. Digested sludge in the fermenter circulates between the membrane separation tank and the methane fermenter via a circulation channel,
In the discharge state, a stirring flow is generated in the methane fermentation tank by the biogas discharged from the discharge means.

  According to this, in the diffused state, an upward flow is generated in the membrane separation tank by the biogas diffused from the diffuser, and the digested sludge of the methane fermentation tank is driven by this upward flow as the driving flow. By circulating through the circulation channel between the methane fermentation tank and the methane fermentation tank, the digested sludge in the methane fermentation tank is agitated and the membrane surface of the membrane separation means is washed.

Moreover, in the discharge state, since the stirring flow is generated in the methane fermentation tank by the biogas discharged from the discharge means, the digested sludge in the methane fermentation tank is stirred.
The sixth invention comprises a methane fermentation tank for performing methane fermentation of organic substances in digested sludge, a membrane separation tank having immersion type membrane separation means for concentrating solids in the digested sludge, A circulation channel for circulating digested sludge between the fermenter and the membrane separation tank, and an aeration that diffuses biogas produced in the membrane separation tank and generated in the methane fermentation tank from below the membrane separation means A methane fermentation treatment method using a membrane methane fermentation treatment apparatus having means,
Aeration operation in which biogas is supplied to the diffusion means and diffused from the diffusion means into the membrane separation tank while the gas supply means is driven, and methane fermentation from the discharge port by supplying biogas to the discharge means The discharge operation for discharging into the digested sludge in the tank is switched.

  According to this, while the gas supply means is being driven, the aeration from the aeration means is stopped and the inside of the methane fermentation tank can be agitated, so even when maintaining the membrane separation means, the gas supply means There is no need to stop driving. Therefore, stirring in the methane fermentation tank can be continued and temperature drop of the gas supply means can be prevented, so that condensation is generated in the gas supply means and the gas supply means is prevented from being damaged. be able to. Further, it is not necessary to frequently stop and start the gas supply means, and wear of the gas supply means can be suppressed.

In the discharge operation, the methane fermentation treatment method according to the seventh invention discharges digested sludge in the membrane separation tank from the discharge port into the digested sludge in the methane fermentation tank in addition to biogas.
In the methane fermentation treatment method according to the eighth aspect of the invention, in the discharge operation, biogas is discharged from the discharge port into the digested sludge in the methane fermentation tank via the air diffuser.
At this time, the digested sludge in the membrane separation tank is sucked from the air holes formed in the air diffuser, and discharged together with the biogas from the discharge port into the digested sludge in the methane fermentation tank.

In the methane fermentation treatment method according to the ninth aspect of the present invention, in the aeration operation, an upward flow is generated in the membrane separation tank by the biogas diffused from the aeration means, and this upward flow is used as the driving flow to generate the methane fermentation tank. Digested sludge circulates between the membrane separation tank and the methane fermentation tank through a circulation channel,
In the discharge operation, a stirring flow is generated in the methane fermentation tank by the biogas discharged from the discharge means.

  As described above, according to the present invention, the stirring in the methane fermentation tank can be continued even when the membrane separation means is maintained, etc., and damage to the gas supply means can be prevented. , Stable aeration can be performed.

It is a figure of the membrane type methane fermentation processing apparatus in the 1st Embodiment of this invention, and shows the flow of the gas when performing a diffused operation. It is a figure of a membrane type | mold methane fermentation processing apparatus, and shows the flow of the gas when performing the 1st discharge driving | operation. It is a figure of a membrane type | mold methane fermentation processing apparatus, and shows the flow of the gas when performing 2nd discharge operation. It is a figure of the membrane type methane fermentation processing apparatus in the 2nd Embodiment of this invention. It is a figure of the membrane type methane fermentation processing apparatus in the 3rd Embodiment of this invention. It is a figure of the membrane type methane fermentation processing apparatus in the 4th Embodiment of this invention. It is a figure of the membrane type methane fermentation processing apparatus in the 5th Embodiment of this invention. It is a figure of the membrane type methane fermentation processing apparatus in the 6th Embodiment of this invention. It is a figure of the membrane type methane fermentation processing apparatus in the 7th Embodiment of this invention. It is a figure of the conventional membrane type methane fermentation processing apparatus.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, 11 is a membrane-type methane fermentation treatment apparatus for treating methane fermentation of an organic substance, a methane fermentation tank 12 for performing methane fermentation of an organic substance in digested sludge, and a methane fermentation tank 12. And a concentration channel 13 for concentrating the solid content in the digested sludge by circulating the digested sludge therein.

  The concentration flow path 13 communicates with a membrane separation tank 14 provided with a submerged membrane separation means 18 inside, the methane fermentation tank 12 and the upper part of the membrane separation tank 14, and digested sludge is methane from the membrane separation tank 14. An upper circulation line 15 that flows into the fermenter 12, a lower circulation line 16 that communicates with the lower part of the methane fermentation tank 12 and the membrane separation tank 14, and through which digested sludge flows out of the methane fermentation tank 12 to the membrane separation tank 14; have. The upper and lower circulation lines 15 and 16 are an example of a circulation channel for circulating the digested sludge between the methane fermentation tank 12 and the membrane separation tank 14.

  The membrane separation means 18 is a device in which a plurality of flat membrane cartridges arranged in parallel with a predetermined interval are arranged in the vertical direction, and a flow path is formed between the membrane cartridges. In each membrane cartridge, filtration membranes are arranged on both sides of the filter plate, and the permeate flow path communicates with the water collection part, and the water collection part communicates with the permeate discharge pipe for extracting the membrane permeate.

  The membrane separation means 18 is gravity filtered by a membrane cartridge using the water head pressure in the membrane separation tank 14 as a driving pressure. In addition, not only gravity filtration but suction filtration may be performed by inserting a suction pump in the permeate outlet tube.

  Further, in the membrane separation tank 14, an aeration means 19 for diffusing the biogas in the methane fermentation tank 12 from below the membrane separation means 18, and a sediment (sludge etc.) settled at the bottom of the membrane separation tank 14. ) Is transferred to the outside of the membrane separation tank 14 (an example of a sediment transfer means).

  Further, the membrane methane fermentation treatment apparatus 11 includes a discharge means 23 for discharging biogas in the methane fermentation tank 12 from a discharge port 22 opened in the digested sludge in the methane fermentation tank 12, and a methane fermentation tank 12. A common blower device 24 (an example of a gas supply device) that supplies biogas to the air diffuser 19 and the discharge device 23, and the biogas supplied by the blower device 24 from the air diffuser 19 to the membrane separation tank 14 Switching means 25 is provided for switching between a diffused state in which air is diffused and a discharge state in which the biogas is discharged from discharge means 23 into methane fermentation tank 12.

The suction side of the blower device 24 and the upper part of the methane fermentation tank 12 communicate with each other via a suction side flow passage 34, and a discharge side flow passage 35 is provided on the discharge side of the blower device 24.
The air diffuser 19 includes a diffuser pipe 28 having a plurality of diffuser holes 27 formed in the lower part thereof, and a flow path that branches from the discharge side flow path 35 of the blower device 24 and communicates with the upstream side (inlet side) of the diffuser pipe 28. 29.

  The discharge means 23 includes a discharge pipe 30 having a downstream end (one end) provided with a discharge port 22 entering the methane fermentation tank 12 and an upstream end (the other end) communicating with the downstream side (outlet side) of the aeration pipe 28. The flow path 32 branched from the discharge side flow path 35 of the blower device 24 and communicated with the upstream side (inlet side) of the sediment suction pipe 20, the downstream side (outlet side) of the sediment suction pipe 20, and the discharge pipe 30. And a flow passage 33 communicating with each other. In addition, the discharge port 22 is opened in the digested sludge in the methane fermentation tank 12, and each said flow path 29 and 32-35 is comprised with piping.

  Further, the sediment suction tube 20 has a plurality of suction holes 36 in the lower portion thereof, and is disposed below the diffuser tube 28. The discharge port 22 is located on the downstream side via the air diffusion pipe 28 and is located on the downstream side via the sediment suction pipe 20. The depth D1 from the liquid level in the methane fermentation tank 12 to the discharge port 22 is formed to be shallower than the depth D2 from the liquid level in the methane fermentation tank 12 to the diffusion tube 28, thereby acting on the discharge port 22. The water head pressure in the methane fermentation tank 12 is lower than the water head pressure in the membrane separation tank 14 acting on the diffuser tube 28 and lower than the water head pressure in the membrane separation tank 14 acting on the sediment suction pipe 20.

  In addition, an external discharge pipe 37 for discharging the sediment sucked from the suction hole 36 of the sediment suction pipe 20 to the outside of the system of the membrane methane fermentation treatment apparatus 11 is provided to be branched from the flow passage 33. Note that the pressure acting on the open end 37a of the external discharge pipe 37 is lower than the hydraulic head pressure acting on the sediment suction pipe 20, or is open to the atmosphere.

  The switching means 25 includes a first valve 25 a provided in the flow passage 29, a second valve 25 b provided in the flow passage 32, and third and fourth valves 25 c provided in the discharge pipe 30. 25d, a fifth valve 25e provided in the flow passage 33, and a sixth valve 25f provided in the external discharge pipe 37. The flow passage 33 is connected to the discharge pipe 30 between the third valve 25c and the fourth valve 25d.

  Further, a gas return pipe 39 for returning the biogas accumulated in the upper part of the membrane separation tank 14 to the gas phase section 38 in the upper part of the methane fermentation tank 12 is provided in communication with the membrane separation tank 14 and the methane fermentation tank 12. ing.

Hereinafter, the operation of the above configuration will be described.
When performing the air diffusion operation, the first valve 25a is opened while the blower device 24 is driven, and the second to sixth valves 25b to 25f are closed. As a result, as shown in FIG. 1, the biogas in the methane fermentation tank 12 passes through the flow passage 29 through the blower device 24 and blows out into the membrane separation tank 14 from the diffuser holes 27 of the diffuser pipe 28. As a result, an upward flow 41 is generated by the air lift action, and the digested sludge in the membrane separation tank 14 flows into the methane fermentation tank 12 through the upper circulation line 15 using the upward flow 41 as a driving flow. The digested sludge in the methane fermentation tank 12 flows into the membrane separation tank 14 through the lower circulation line 16, and the digested sludge in the methane fermentation tank 12 circulates through the concentration channel 13 with the membrane separation tank 14. To do. For this reason, the digested sludge in the methane fermentation tank 12 is agitated, and at the same time, the upward flow 41 flows as a sweep flow through the flow path between the membranes of the membrane separation means 18, so that the membrane surface of the membrane separation means 18 Is washed by the upward flow 41.

The digested sludge that has flowed into the membrane separation tank 14 from the methane fermentation tank 12 is sucked and solid-liquid separated by the membrane separation means 18, and the permeate is taken out from the membrane separation means 18.
As described above, during the aeration operation, the digested sludge in the methane fermentation tank 12 and the membrane surface cleaning of the membrane separation tank 14 can be performed together by the aeration from the aeration pipe 28.

  Further, when stopping the suction of digested sludge by the membrane separation means 18 for the purpose of maintenance or the like and stopping the membrane separation (solid-liquid separation), the switching means 25 is operated while the blower device 24 is continuously driven. Then, switching from the aeration operation to the first or second discharge operation is performed.

  For example, when switching to the first discharge operation, the third and fourth valves 25c and 25d are further opened while the first valve 25a is opened, and the second, fifth and sixth valves 25b and 25e are opened. 25f are closed. As a result, as shown in FIG. 2, the biogas in the methane fermentation tank 12 flows through the blower device 24, the flow path 29, the diffusing pipe 28, and the discharge pipe 30. To the digested sludge in the methane fermentation tank 12.

  At this time, since the water head pressure in the methane fermentation tank 12 acting on the discharge port 22 is lower than the water head pressure in the membrane separation tank 14 acting on the diffuser tube 28, the biogas is almost from the diffuser holes 27 of the diffuser tube 28. It is discharged from the discharge port 22 without being diffused. At this time, digested sludge in the membrane separation tank 14 is sucked into the diffuser tube 28 from the diffuser holes 27 by the suction action (ejector effect) generated by the difference between the head pressures and the flow of biogas flowing in the diffuser tube 28. Then, it is discharged into the digested sludge in the methane fermentation tank 12 from the discharge port 22 together with the biogas.

  As a result, a gas-liquid mixed phase flow in which biogas and digested sludge are mixed is discharged into the digested sludge in the methane fermentation tank 12 from the discharge port 22, and the discharge flow 40 and air lift due to the digested sludge are discharged into the methane fermentation tank 12. An upward flow 42 is generated by the action, and the discharge flow 40 and the upward flow 42 generate a stirring flow 43 in the methane fermentation tank 12, and the digested sludge in the methane fermentation tank 12 is continuously stirred. The In addition, since it becomes a gas-liquid mixed phase flow as mentioned above, since bubbles become small, stirring is made uniform.

  In this way, while the blower device 24 is driven, the aeration from the diffusion tube 28 is stopped, and the inside of the methane fermentation tank 12 can be stirred. Therefore, even when the membrane separation means 18 is maintained, the blower device 24 is maintained. There is no need to stop driving. Therefore, the stirring in the methane fermentation tank 12 can be continued and the temperature drop of the blower device 24 can be prevented, so that condensation is generated in the blower device 24 and the blower device 24 is prevented from being damaged. can do. Further, the digested sludge is sucked into the diffuser tube 28, so that the effect of cleaning the diffuser tube 28 is also obtained.

  Further, while the membrane separation (solid-liquid separation) is stopped, no upward flow is generated in the membrane separation tank 14, and the membrane surface of the membrane separation means 18 is not exposed to the upward flow. Thereby, it is possible to reduce damage to the membrane while maintaining stirring in the methane fermentation tank 12, and it is not necessary to frequently stop and start the blower device 24, thereby suppressing wear of the blower device 24. be able to.

  In the above embodiment, the case of switching from the aeration operation to the first discharge operation has been described. However, the operation may be switched from the aeration operation to the second discharge operation. In this case, the first, third, and sixth valves 25a, 25c, and 25f are closed, and the second, fourth, and fifth valves 25b, 25d, and 25e are opened. Thereby, as shown in FIG. 3, the biogas generated in the methane fermentation tank 12 passes through the flow passage 32 through the blower device 24, and is discharged from the flow passage 33 through (passes) the sediment suction pipe 20. It flows through the pipe 30 and is discharged from the discharge port 22 into the digested sludge in the methane fermentation tank 12.

  At this time, since the head pressure in the methane fermentation tank 12 acting on the discharge port 22 is lower than the head pressure in the membrane separation tank 14 acting on the sediment suction pipe 20, the biogas is sucked into the sediment suction pipe 20. The liquid is discharged from the discharge port 22 with hardly being blown out from the hole 36. At this time, the sediment (sludge and the like) in the membrane separation tank 14 is sucked from the suction hole 36 into the sediment suction pipe by the suction action caused by the difference between the two head pressures and the flow of the biogas flowing in the sediment suction pipe 20. It is sucked into 20 and discharged into the digested sludge in the methane fermentation tank 12 from the discharge port 22 together with the biogas.

  As a result, a gas-liquid mixed phase flow in which biogas and digested sludge are mixed is discharged into the digested sludge in the methane fermentation tank 12 from the discharge port 22, and the discharge flow 40 and the air lift due to the sediment are injected into the methane fermentation tank 12. An upward flow 42 is generated by the action, and the discharge flow 40 and the upward flow 42 generate a stirring flow 43 in the methane fermentation tank 12, and the digested sludge in the methane fermentation tank 12 is continuously stirred. The In addition, the sediment suction pipe 20 sucks the sediment, so that the amount of sediment that settles and accumulates at the bottom of the membrane separation tank 14 can be reduced. It can be prevented from exceeding. Therefore, when the second discharge operation is switched to the aeration operation and the aeration tube 28 performs the aeration, the aeration is stabilized and the membrane surface cleaning of the membrane separation means 18 can be performed almost uniformly.

  Further, the first and third and fourth valves 25a, 25c and 25d are closed, and the second and fifth and sixth valves 25b, 25e and 25f are opened, so that the sediment sucked from the sediment suction pipe 20 is collected. An object passes through the external discharge pipe 37 and is discharged from the open end 37a to the outside of the system. Thereby, the substance with large specific gravity in sludge can be discharged | emitted from the opening end 37a, and can be collect | recovered.

The valves 25c, 25d, and 25e can be collectively replaced with a single three-way switching valve.
Next, a second embodiment of the present invention will be described with reference to FIG.

The air diffuser 19 includes an air diffuser 28 and a flow passage 29 that branches from the discharge side flow passage 35 of the blower device 24 and communicates with the upstream side (inlet side) of the air diffuser 28.
The discharge means 23 has a discharge pipe 30 that branches from the discharge side flow passage 35 of the blower device 24 and enters the methane fermentation tank 12. The discharge pipe 30 has a discharge port 22 that opens into the digested sludge in the methane fermentation tank 12 at the downstream end.

The switching means 25 includes a first valve 25 a provided in the flow passage 29 and a second valve 25 b provided in the discharge pipe 30.
Hereinafter, the operation of the above configuration will be described.

  When performing the air diffusion operation, the first valve 25a is opened and the second valve 25b is closed while the blower device 24 is driven. Thereby, the biogas in the methane fermentation tank 12 passes through the flow path 35 through the blower device 24, flows through the flow path 29, and is blown out from the diffuser tube 28 into the membrane separation tank 14. As a result, an upward flow 41 is generated, and the digested sludge in the methane fermentation tank 12 circulates through the concentration channel 13 with the membrane separation tank 14.

  Further, when the suction of digested sludge by the membrane separation means 18 is stopped to stop the membrane separation (solid-liquid separation), the aeration operation is performed by operating the switching means 25 while the blower device 24 is continuously driven. Switch to discharge operation.

  That is, in the discharge operation, the first valve 25a is closed and the second valve 25b is opened. Thereby, the biogas produced | generated in the methane fermentation tank 12 passes along the flow path 35 through the blower apparatus 24, flows through the discharge pipe 30, and is discharged in the digested sludge in the methane fermentation tank 12 from the discharge port 22. .

  Thereby, the aeration from the aeration tube 28 is stopped, the biogas is discharged from the discharge port 22 into the digested sludge in the methane fermentation tank 12, and the digested sludge in the methane fermentation tank 12 is continuously stirred.

Next, a third embodiment of the present invention will be described with reference to FIG.
The air diffuser 19 has an air diffuser 28 connected to the discharge side flow passage 35 of the blower device 24. The discharge means 23 is composed of a discharge pipe 30 whose upstream end (one end) is connected to the downstream side (exit side) of the diffusion tube 28 and whose downstream end (the other end) enters the methane fermentation tank 12. The discharge pipe 30 has a discharge port 22 that opens into the digested sludge in the methane fermentation tank 12 at the downstream end. The switching means 25 includes a seventh valve 25g provided in the discharge pipe 30.

  The depth D1 from the liquid level in the methane fermentation tank 12 to the discharge port 22 is formed to be shallower than the depth D2 from the liquid level in the methane fermentation tank 12 to the diffusion tube 28, thereby acting on the discharge port 22. The water head pressure in the methane fermentation tank 12 is lower than the water head pressure in the membrane separation tank 14 acting on the diffuser tube 28.

Hereinafter, the operation of the above configuration will be described.
When performing the air diffusion operation, the seventh valve 25g is closed while the blower device 24 is driven. Thereby, the biogas in the methane fermentation tank 12 passes through the discharge side flow passage 35 through the blower device 24 and blows out from the diffuser pipe 28 into the membrane separation tank 14. As a result, an upward flow 41 is generated, and the digested sludge in the methane fermentation tank 12 circulates through the concentration channel 13 with the membrane separation tank 14.

  Further, when the suction of digested sludge by the membrane separation means 18 is stopped to stop the membrane separation (solid-liquid separation), the aeration operation is performed by operating the switching means 25 while the blower device 24 is continuously driven. Switch to discharge operation.

  That is, in the discharge operation, the seventh valve 25g is opened. As a result, the biogas generated in the methane fermentation tank 12 flows (passes) through the diffusion pipe 28, flows through the discharge pipe 30, and is discharged from the discharge port 22 into the digested sludge in the methane fermentation tank 12.

  At this time, since the water head pressure in the methane fermentation tank 12 acting on the discharge port 22 is lower than the water head pressure in the membrane separation tank 14 acting on the diffuser tube 28, the biogas is almost from the diffuser holes 27 of the diffuser tube 28. It is discharged from the discharge port 22 without being diffused. At this time, the digested sludge in the membrane separation tank 14 is sucked into the diffuser tube 28 from the diffuser hole 27 by the suction action generated by the difference between the both head pressures and the flow of the biogas flowing in the diffuser tube 28, It is discharged into the digested sludge in the methane fermentation tank 12 from the discharge port 22 together with the gas.

  As a result, a gas-liquid mixed phase flow in which biogas and digested sludge are mixed is discharged from the discharge port 22 into the digested sludge in the methane fermentation tank 12, and a stirring flow 43 is generated in the methane fermentation tank 12. The digested sludge in the fermenter 12 is continuously stirred.

Thus, while the blower device 24 is being driven, the aeration from the aeration tube 28 is stopped and the inside of the methane fermentation tank 12 can be agitated.
Next, a fourth embodiment of the present invention will be described with reference to FIG.

The air diffuser 19 includes an air diffuser 28 and a flow passage 29 that branches from the discharge side flow passage 35 of the blower device 24 and communicates with the upstream side (inlet side) of the air diffuser 28.
The discharge means 23 branches from the discharge side flow path 35 of the blower device 24 and communicates with the upstream side (inlet side) of the sediment suction pipe 20, and the upstream end (one end) of the sediment suction pipe 20. It has a discharge pipe 30 that communicates with the downstream side (exit side) and whose downstream end (the other end) enters the methane fermentation tank 12. In addition, the discharge pipe 30 has the discharge port 22 opened in the digested sludge in the methane fermentation tank 12 in a downstream end.

  The switching means 25 includes a first valve 25 a provided in the flow passage 29 and a second valve 25 b provided in the flow passage 32. The depth D1 from the liquid level in the methane fermentation tank 12 to the discharge port 22 is formed to be shallower than the depth D3 from the liquid level in the methane fermentation tank 12 to the sediment suction pipe 20. The head pressure in the working methane fermentation tank 12 is lower than the head pressure in the membrane separation tank 14 acting on the sediment suction pipe 20.

Hereinafter, the operation of the above configuration will be described.
When performing the air diffusion operation, the first valve 25a is opened and the second valve 25b is closed while the blower device 24 is driven. Thereby, the biogas generated in the methane fermentation tank 12 passes through the discharge side flow passage 35 through the blower device 24, flows through the flow passage 29, and is blown out from the diffuser tube 28 into the membrane separation tank 14. As a result, an upward flow 41 is generated, and the digested sludge in the methane fermentation tank 12 circulates through the concentration channel 13 with the membrane separation tank 14.

  Further, when the suction of digested sludge by the membrane separation means 18 is stopped to stop the membrane separation (solid-liquid separation), the aeration operation is performed by operating the switching means 25 while the blower device 24 is continuously driven. Switch to discharge operation.

  That is, in the discharge operation, the second valve 25b is opened and the first valve 25a is closed. Thereby, the biogas generated in the methane fermentation tank 12 passes through the discharge side flow passage 35 via the blower device 24 and flows through the discharge pipe 30 from the flow passage 32 through (passes) the sediment suction pipe 20. And discharged from the discharge port 22 into the digested sludge in the methane fermentation tank 12.

  At this time, since the head pressure in the methane fermentation tank 12 acting on the discharge port 22 is lower than the head pressure in the membrane separation tank 14 acting on the sediment suction pipe 20, the biogas is sucked into the sediment suction pipe 20. The liquid is discharged from the discharge port 22 with hardly being blown out from the hole 36. At this time, the sediment (sludge and the like) in the membrane separation tank 14 is sucked from the suction hole 36 into the sediment suction pipe by the suction action caused by the difference between the two head pressures and the flow of the biogas flowing in the sediment suction pipe 20. It is sucked into 20 and discharged into the digested sludge in the methane fermentation tank 12 from the discharge port 22 together with the biogas.

  Thereby, the gas-liquid mixed phase flow in which biogas and digested sludge are mixed is discharged from the discharge port 22 into the digested sludge in the methane fermentation tank 12, and the digested sludge in the methane fermentation tank 12 is continuously stirred. .

Next, a fifth embodiment of the present invention will be described with reference to FIG.
Between the lower part of the methane fermentation tank 12 and the upper part of the membrane separation tank 14, there is provided a delivery flow passage 50 for forcibly sending the digested sludge in the methane fermentation tank 12 into the membrane separation tank 14 by the pump 52. Yes. Further, a return flow passage 51 is provided between the upper part of the methane fermentation tank 12 and the lower part of the membrane separation tank 14 to return the digested sludge in the membrane separation tank 14 into the methane fermentation tank 12 with a pump 53. It has been. The concentration flow path 13 is formed by the delivery flow path 50, the return flow path 51, and the membrane separation tank 14, and the delivery and return flow paths 50, 51 are formed by the methane fermentation tank 12 and the membrane separation tank. 14 is an example of a circulation channel that circulates digested sludge between the two.

The air diffuser 19 has an air diffuser 28 connected to the discharge side flow passage 35 of the blower device 24.
The discharge means 23 includes a discharge pipe 30 whose upstream end is connected to the downstream side (exit side) of the diffusion tube 28 and whose downstream end enters the methane fermentation tank 12. The discharge pipe 30 has a discharge port 22 that opens into the digested sludge in the methane fermentation tank 12 at the downstream end. The switching means 25 includes a seventh valve 25g provided in the discharge pipe 30.

  The depth D1 from the liquid level in the methane fermentation tank 12 to the discharge port 22 is formed to be shallower than the depth D2 from the liquid level in the membrane separation tank 14 to the diffusion tube 28, thereby acting on the discharge port 22. The water head pressure in the methane fermentation tank 12 is lower than the water head pressure in the membrane separation tank 14 acting on the diffuser tube 28.

Hereinafter, the operation of the above configuration will be described.
When performing the air diffusion operation, the seventh valve 25g is closed while the pumps 52 and 53 and the blower device 24 are driven. Thereby, the biogas produced in the methane fermentation tank 12 passes through the discharge side flow passage 35 through the blower device 24 and blows out into the membrane separation tank 14 from the diffuser tube 28. Thereby, the upward flow 41 is generated and the membrane surface of the membrane separation means 18 is washed. At this time, by driving the pumps 52 and 53, the digested sludge in the methane fermentation tank 12 is forcibly sent out into the membrane separation tank 14 through the delivery flow passage 50, and is solid-liquid separated by the membrane separation means 18. The digested sludge in the membrane separation tank 14 is forcibly returned to the methane fermentation tank 12 through the return flow passage 51. Thereby, the digested sludge in the methane fermentation tank 12 circulates between the membrane separation tank 14 via the flow passages 50 and 51 for sending and returning, and the inside of the methane fermentation tank 12 is stirred.

  Further, when the suction of digested sludge by the membrane separation means 18 is stopped to stop the membrane separation (solid-liquid separation), the pumps 52 and 53 are stopped and sent out while the blower device 24 is continuously driven. The valve 54 provided in the flow passage 50 is closed, and the switching means 25 is operated to switch from the aeration operation to the discharge operation.

  That is, in the discharge operation, the seventh valve 25g is opened. As a result, the biogas generated in the methane fermentation tank 12 flows (passes) through the diffusion pipe 28, flows through the discharge pipe 30, and is discharged from the discharge port 22 into the digested sludge in the methane fermentation tank 12.

  At this time, since the head pressure in the methane fermentation tank 12 acting on the discharge port 22 is lower than the head pressure in the membrane separation tank 14 acting on the diffuser tube 28, the biogas is hardly diffused from the diffuser tube 28. Then, the ink is discharged from the discharge port 22. At this time, the digested sludge in the membrane separation tank 14 is sucked into the air diffuser 28 by the suction action generated by the difference between the head pressures and the flow of the biogas flowing in the air diffuser 28, and is discharged together with the biogas. 22 is discharged into the digested sludge in the methane fermentation tank 12, and the stirring in the methane fermentation tank 12 is continued.

  In addition, the amount of sediment that settles and accumulates at the bottom of the membrane separation tank 14 can be reduced, and when aeration is performed from the aeration tube 28 by switching from the discharge operation to the aeration operation, the aeration is stabilized. The membrane surface of the membrane separation means 18 can be cleaned almost uniformly.

Next, a sixth embodiment of the present invention will be described with reference to FIG.
The sixth embodiment is a modification of the above-described fifth embodiment, and a plurality of membrane separation tanks 14 are provided for one common methane fermentation tank 12. A plurality of membrane separation means 18 are provided in each membrane separation tank 14. A blower device 24, an air diffuser 19, a discharger 23, and a switching unit 25 are provided for each membrane separation tank 14. The air diffuser 19 has a collecting pipe made up of a plurality of air diffusing pipes 28, and the discharge means 23 has a collecting pipe made up of a sediment suction pipe 20. The aeration tube 28 and the sediment suction tube 20 are respectively provided below the plurality of membrane separation means 18. Further, the discharge pipes 30 of the plurality of discharge means 23 are arranged radially and enter the methane fermentation tank 12.

  In the sixth embodiment, a plurality of membrane separation tanks 14 are arranged in parallel as shown in FIG. 8A. However, in the seventh embodiment shown in FIG. The tank 14 may be arranged radially with respect to the methane fermentation tank 12.

  In each of the above embodiments, a flat membrane cartridge is used as the membrane separation means 18, but it may be a cylindrical (circular tube) membrane cartridge or the like, and a membrane other than a flat membrane, for example, a hollow fiber membrane Etc. may be used. At this time, in the case of a flat membrane cartridge in which a filtration membrane is disposed on the surface of a flat plate or sheet-like membrane support material and joined to the membrane support material at the periphery of the filtration membrane, It is possible to prevent mind. For this reason, it is possible to avoid damage to the joint portion of the filtration membrane due to the vibration or swinging of the filtration membrane due to the upward flow caused by the aeration. Therefore, particularly for the flat membrane cartridge as described above It is valid.

In each of the above-described embodiments, the hydraulic head pressure acting on the discharge port 22 is set lower than the hydraulic head pressure applied to the diffuser tube 28, but it may be the same.
In each said embodiment, although the biogas stored by the upper part in the methane fermentation tank 12 is supplied to the blower apparatus 24, the biogas supplied to the blower apparatus 24 was produced | generated by the methane fermentation tank 12 For example, the biogas stored in the upper part in the membrane separation tank 14 or the biogas stored in the gas holder may be supplied to the blower device 24.

DESCRIPTION OF SYMBOLS 11 Membrane-type methane fermentation treatment apparatus 12 Methane fermentation tank 14 Membrane separation tanks 15 and 16 Circulation line (circulation flow path)
18 Membrane separation means 19 Aeration means 20 Sediment suction tube (sediment transfer means)
22 Discharge port 23 Discharge means 24 Blower device (gas supply means)
25 Switching means 27 Aeration hole 36 Suction holes 41, 42 Upflow 43 Stirring flow 50 Outflow passage (circulation passage)
51 Return channel (circulation channel)

Claims (9)

A methane fermentation tank that performs methane fermentation of organic substances in digested sludge, a membrane separation tank that is equipped with a submerged membrane separation means for concentrating solids in digested sludge, a methane fermentation tank, and a membrane separation tank And a circulation channel for circulating the digested sludge between and a membrane type having an aeration means for aerating biogas generated in the membrane separation tank and generated in the methane fermentation tank from below the membrane separation means A methane fermentation treatment apparatus,
A discharge means for discharging biogas from a discharge port opened in the digested sludge in the methane fermentation tank;
A common gas supply means for supplying biogas to the aeration means and the discharge means;
Switching means capable of switching between a diffused state where the biogas supplied by the gas supply means is diffused from the diffuser means into the membrane separation tank and a discharge state where the biogas is discharged from the discharge means into the methane fermentation tank; Is provided with a membrane type methane fermentation treatment apparatus. The membrane-type methane fermentation treatment apparatus according to claim 1, wherein the aeration means and the discharge means are branched from the gas supply means. The discharge means has a sediment transfer means for sucking the sediment in the membrane separation tank from the suction hole and transferring it to the outside of the membrane separation tank,
The sediment transfer means is arranged below the aeration means,
The discharge port is located downstream via the sediment transfer means,
3. The membrane type methane according to claim 2, wherein the head pressure in the methane fermentation tank acting on the discharge port is configured to be lower than the head pressure in the membrane separation tank acting on the sediment transfer means. Fermentation processing equipment. The discharge port is located on the downstream side through the air diffuser,
The membrane type methane fermentation according to claim 1, wherein the head pressure in the methane fermentation tank acting on the discharge port is configured to be lower than the head pressure in the membrane separation tank acting on the aeration means. Processing equipment. In the diffused state, an upward flow is generated in the membrane separation tank due to the biogas diffused from the diffuser, and the digested sludge of the methane fermentation tank is converted into the membrane separation tank and the methane fermentation tank using this upward flow as the driving flow. Circulate through the circulation channel between
The membrane-type methane fermentation treatment according to any one of claims 1 to 4, wherein a stirring flow is generated in the methane fermentation tank by the biogas discharged from the discharge means in the discharge state. apparatus. A methane fermentation tank for methane fermentation of organic substances in digested sludge, a membrane separation tank equipped with an immersion type membrane separation means for concentrating solids in digested sludge, a methane fermentation tank and a membrane separation tank And a circulation channel for circulating the digested sludge between and a membrane type having an aeration means for aerating biogas generated in the membrane separation tank and generated in the methane fermentation tank from below the membrane separation means A methane fermentation treatment method using a methane fermentation treatment apparatus,
Aeration operation in which biogas is supplied to the diffusion means and diffused from the diffusion means into the membrane separation tank while the gas supply means is driven, and methane fermentation from the discharge port by supplying biogas to the discharge means A methane fermentation treatment method characterized by switching between a discharge operation for discharging into digested sludge in a tank. In the discharge operation, in addition to biogas, the digested sludge in the membrane separation tank is discharged from the discharge port into the digested sludge in the methane fermentation tank. In the discharge operation, biogas is discharged from the discharge port into the digested sludge in the methane fermentation tank via the air diffuser,
8. At this time, digested sludge in the membrane separation tank is sucked from the air holes formed in the air diffuser and discharged together with biogas into the digested sludge in the methane fermentation tank from the discharge port. Methane fermentation treatment method. In the aeration operation, an upward flow is generated in the membrane separation tank by the biogas diffused from the diffusion means, and the digested sludge of the methane fermentation tank is converted into the membrane separation tank and the methane fermentation tank by using this upward flow as a driving flow. Circulate through the circulation channel between
9. The methane fermentation treatment method according to claim 6, wherein in the discharge operation, a stirring flow is generated in the methane fermentation tank by the biogas discharged from the discharge means.

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