WO2023042550A1

WO2023042550A1 - Organic wastewater treatment method and treatment device

Info

Publication number: WO2023042550A1
Application number: PCT/JP2022/028835
Authority: WO
Inventors: 柳瀬哲也; 安井英斉; 寺嶋光春
Original assignee: メタウォーター株式会社; 公立大学法人北九州市立大学
Priority date: 2021-09-15
Filing date: 2022-07-26
Publication date: 2023-03-23

Abstract

Provided is an organic wastewater treatment method in an organic wastewater treatment device. The organic wastewater treatment device comprises: a reaction tank in which a biological treatment is performed on a pollutant that is contained in organic wastewater; a solid-liquid separation device which separates sludge from wastewater that has been discharged from the reaction tank; and a feeder which feeds at least oxygen to the reaction tank. The reaction tank has a tubular membrane carrier that causes molecular diffusion, in the reaction tank via a plurality of holes, of oxygen which has been fed by the feeder. The membrane carrier causes the molecular diffusion of the oxygen in the reaction tank via the plurality of holes so as to form a biological membrane that contains aerobic bacteria on the outer circumference of the membrane carrier. The biological membrane subjects the pollutant to a biological treatment via the aerobic bacteria. The solid-liquid separation device separates sludge containing the biological membrane from the wastewater.

Description

Method and apparatus for treating organic wastewater

The present invention relates to a method and apparatus for treating organic wastewater.

A treatment device that treats organic wastewater such as sewage (hereinafter simply referred to as wastewater) uses a method of removing, for example, contaminants (hereinafter simply referred to as contaminants) contained in wastewater. This method is, for example, an activated sludge method in which organic matter is decomposed by microorganisms propagated in a reaction tank (hereinafter also referred to as activated sludge). Contaminants are, for example, organic substances, suspended substances, etc. (hereinafter simply referred to as organic substances or substrates) (see Patent Document 1).

JP 2021-079335 A

It is desired to suppress running costs in the above organic wastewater treatment equipment.

According to one aspect of the embodiment, there is provided an organic wastewater treatment method in an organic wastewater treatment apparatus, wherein the organic wastewater treatment apparatus includes a reaction tank for biologically treating contaminants contained in the organic wastewater. , a solid-liquid separation device for separating sludge from wastewater discharged from the reaction tank, and a feeder for supplying at least oxygen to the reaction tank, wherein the reaction tank is supplied by the feeder. It has a tubular membrane carrier for molecularly diffusing the oxygen into the reaction vessel through the plurality of holes, and the membrane carrier causes the oxygen to molecularly diffuse into the reaction vessel through the plurality of holes. , a biofilm containing aerobic bacteria is formed on the outer periphery of the membrane carrier, the biofilm is a biofilm that performs biological treatment of the contaminants with the aerobic bacteria, and the solid-liquid separation device is and separating said sludge containing said biofilm from said waste water.

According to one aspect, it is possible to reduce running costs.

FIG. 1 is a diagram illustrating the configuration of an organic wastewater treatment apparatus 800 in a first comparative example. FIG. 2 is a diagram illustrating the configuration of an organic wastewater treatment apparatus 900 in a second comparative example. FIG. 3 is a diagram illustrating the configuration of the organic wastewater treatment apparatus 100 according to the first embodiment. FIG. 4 is a vertical sectional view for explaining the configuration of the film carrier 72 in the first embodiment. FIG. 5 is a vertical sectional view for explaining the configuration of the film carrier 72 in the first embodiment. FIG. 6 is a diagram for explaining the effects of the first embodiment. FIG. 7 is a diagram for explaining the effects of the first embodiment. FIG. 8 is a diagram for explaining the effects of the first embodiment. FIG. 9 is a diagram illustrating the configuration of the reaction vessel 70 in the first modified example. FIG. 10 is a diagram illustrating the configuration of the membrane carrier 72 in the first modified example. FIG. 11 is a diagram illustrating the configuration of the membrane carrier 72 in the first modified example.

Embodiments of the present invention will be described below with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention.

[Organic wastewater treatment apparatus 800 in the first comparative example]
First, the configuration of an organic wastewater treatment apparatus 800 (hereinafter also referred to as an organic wastewater treatment system 800) in a first comparative example will be described. FIG. 1 is a diagram illustrating the configuration of an organic wastewater treatment apparatus 800 in a first comparative example. The organic wastewater treatment apparatus 800 treats contaminants by a so-called activated sludge method. Specifically, the organic wastewater treatment apparatus 800 has, for example, a primary sedimentation tank 10, a reaction tank 20, a final sedimentation tank 30, and an air feeder 40, as shown in FIG.

For example, the primary sedimentation tank 10 sediments and separates organic substances (eg, solid organic substances) contained in the wastewater 1 . The primary sedimentation tank 10 discharges the separated organic matter as primary sedimentation sludge to a thickener (not shown), and discharges the waste water 1 from which the organic matter has been separated to the reaction tank 20 .

The reaction tank 20 includes, for example, a tank body 21 from which waste water 1 is discharged from the primary sedimentation tank 10, and air 2 (oxygen ) to treat the wastewater 1 by biological treatment.

Specifically, in the reaction tank 20, for example, an aeration process is performed in which air 2 is supplied to the activated sludge existing in the tank main body 21. In the reaction tank 20 , for example, organic matter (eg, soluble organic matter) contained in the wastewater 1 is decomposed (consumed) by activated sludge supplied with the air 2 . After that, the reaction tank 20 discharges the wastewater 1 after decomposition of organic matter by activated sludge, for example, to the final sedimentation tank 30 .

The final sedimentation tank 30, for example, sediments and separates the sludge contained in the wastewater 1 discharged from the reaction tank 20, and discharges the separated sludge as activated sludge. For example, the final sedimentation tank 30 supplies part of the activated sludge as excess sludge to a thickener (not shown), and returns activated sludge other than the excess sludge to the reaction tank 20 as return sludge. Furthermore, the final sedimentation tank 30 discharges the waste water 1 (supernatant liquid) from which the activated sludge has been separated, for example, to a post-stage sterilization apparatus (not shown). After that, the sterilization apparatus sterilizes the wastewater 1 discharged from the final sedimentation tank 30, for example, and discharges the sterilized treated water.

The air supplier 40 is, for example, an air blower and supplies the air 2 to the reaction vessel 20. Specifically, the air supplier 40 supplies the air 2 into the reaction vessel 20 through the air supply pipe 22 provided at the bottom of the reaction vessel 20 .

Here, in the organic wastewater treatment apparatus 800, separation of activated sludge in the final sedimentation tank 30 is performed by natural sedimentation. Therefore, for example, if the activated sludge does not settle sufficiently due to bulking or the like, the organic wastewater treatment apparatus 800 may carry over the activated sludge to the subsequent apparatus.

Also, in the organic wastewater treatment apparatus 800 , the concentration of activated sludge in the reaction tank 20 changes depending on the amount of returned sludge from the final sedimentation tank 30 . Therefore, the concentration of activated sludge in the reaction tank 20 depends on the natural settling property in the final sedimentation tank 30 and the size of the final sedimentation tank 30, and may become unstable.

Furthermore, in the organic wastewater treatment apparatus 800, the power for supplying the air 2 by the air supplier 40 may be increased due to the need to maintain the concentration of activated sludge in the reaction tank 20. In addition to the activated sludge method, a membrane separation activated sludge method has been proposed as a method for treating pollutants. The membrane separation activated sludge method will be explained with reference to FIG.

[Organic wastewater treatment apparatus 900 in the second comparative example]
Next, the configuration of an organic wastewater treatment apparatus 900 (hereinafter also referred to as an organic wastewater treatment system 900) in a second comparative example will be described. FIG. 2 is a diagram illustrating the configuration of an organic wastewater treatment apparatus 900 in a second comparative example.

The organic wastewater treatment apparatus 900 is, for example, an organic wastewater treatment apparatus using a membrane separation activated sludge method. Specifically, the organic wastewater treatment apparatus 900 includes, as shown in FIG. have That is, the organic wastewater treatment apparatus 900 has, for example, a solid-liquid separation tank 50 in place of the final sedimentation tank 30 compared to the organic wastewater treatment apparatus 800 . The organic wastewater treatment device 900 further comprises an air feeder 60, for example.

The solid-liquid separation tank 50 includes, for example, a tank body 51 from which waste water 1 is discharged from the reaction tank 20, and air 2 ( oxygen) and a separation membrane 53 for separating activated sludge contained in the wastewater 1 . The separation membrane 53 is, for example, a microfiltration membrane or an ultrafiltration membrane.

Specifically, in the solid-liquid separation tank 50, for example, by aerating the separation membrane 53 from below with the air 2 supplied from the air supply pipe 52, an upward flow of the air 2 and the waste water 1 is generated, and the separation membrane The activated sludge is separated while suppressing clogging caused by proliferation (coating) of the activated sludge in the membrane 53 and clogging of the separation membrane 53 . The solid-liquid separation tank 50 supplies part of the activated sludge as excess sludge to the thickener, and returns the activated sludge other than the excess sludge to the reaction tank 20 as return sludge. The solid-liquid separation tank 50 discharges the wastewater 1 (supernatant liquid) after the separation of the activated sludge to the subsequent sterilization apparatus by sucking it from above with a pump (not shown).

The air supply device 60 is, for example, an air blower, and supplies air 2 to the solid-liquid separation tank 50. Specifically, the air supply device 60 supplies the air 2 to the air supply pipe 52 provided at the bottom of the solid-liquid separation tank 50 .

That is, the organic wastewater treatment apparatus 900 separates activated sludge using the separation membrane 53 instead of separating activated sludge by natural sedimentation. As a result, the organic wastewater treatment apparatus 900 can prevent the activated sludge from flowing out to the subsequent apparatus.

In addition, in the organic wastewater treatment apparatus 900, the concentration of activated sludge separated from the wastewater 1 in the solid-liquid separation tank 50 can be increased. Therefore, in the organic wastewater treatment apparatus 900, for example, the size of the reaction tank 20 can be reduced compared to the organic wastewater treatment apparatus 800 described with reference to FIG.

In addition, the organic wastewater treatment apparatus 900 uses, for example, a circulation pump (not shown) to circulate the activated sludge between the reaction tank 20 and the solid-liquid separation tank 50, and the activated sludge by the separation membrane 53. may be used to separate the Further, the organic wastewater treatment apparatus 900 may have a separation membrane 53 in the reaction tank 20 instead of having the solid-liquid separation tank 50, for example. Moreover, in the membrane separation activated sludge process of FIG. 2, in order to maintain the performance of the reaction tank 50, the excess sludge adhering to the separation membrane 53 can be removed by washing.

Here, in the organic wastewater treatment apparatus 900, for example, the separation membrane 53 is periodically washed with a chemical such as hypochlorous acid or alkali in order to prevent clogging of the separation membrane 53. There is a need. Further, in the organic wastewater treatment apparatus 900, for example, the separation membrane 53 needs to be replaced periodically.

In addition, in the organic wastewater treatment apparatus 900, for example, due to the need to separate activated sludge while preventing clogging of the separation membrane 53, the power of the air supply device 40, the circulation pump, etc. may be increased. .

Furthermore, the main component of the activated sludge separated by the separation membrane 53 is the fungus grown in the wastewater 1. Such excess sludge is dispersed and has the property of being difficult to dewater. Therefore, in the organic wastewater treatment apparatus 900, for example, it is necessary to put a large amount of coagulant in a concentrator or the like. Thus, in the organic wastewater treatment apparatus described in FIGS. 1 and 2, running costs (for example, air supply power, separation membrane replacement costs, cleaning costs, flocculant costs) increase. Therefore, an organic wastewater treatment apparatus capable of suppressing such running costs will be described with reference to FIGS. 3 to 8. FIG.

[Organic wastewater treatment apparatus 100 in the first embodiment]
First, the configuration of an organic wastewater treatment apparatus 100 (hereinafter also referred to as an organic wastewater treatment system 100) in the first embodiment will be described. FIG. 3 is a diagram illustrating the configuration of the organic wastewater treatment apparatus 100 according to the first embodiment. 4 and 5 are vertical cross-sectional views illustrating the configuration of the film carrier 72 in the first embodiment.

The organic wastewater treatment device 100 performs biological treatment on contaminants contained in the organic wastewater 1 . Specifically, the organic wastewater treatment apparatus 100 has, for example, a primary sedimentation tank 10, a reaction tank 70, an air feeder 80, and a solid-liquid separation apparatus 90, as shown in FIG. That is, the organic wastewater treatment apparatus 100 has a reaction tank 70 instead of the reaction tank 20, for example, compared with the organic wastewater treatment apparatus 900. FIG. Further, the organic wastewater treatment apparatus 100 has, for example, an air supplier 80 (hereinafter also referred to as a supplier) in place of the air supplier 40 . Further, the organic wastewater treatment apparatus 100 has, for example, a solid-liquid separation device 90 instead of the solid-liquid separation tank 50 . The air supplier 80 is, for example, a blower such as an air blower or a fan, and supplies at least oxygen to the reaction vessel 70 . The gas supplied by the air supply device 80 may be any other gas as long as it contains oxygen, and hereinafter, air is exemplified as the gas containing oxygen.

The reaction tank 70 performs biological treatment on contaminants contained in organic wastewater. The reaction tank 70 is, for example, a membrane aerated biofilm reactor (MABR: Membrane Aerated Biofilm Reactor). Specifically, the reaction tank 70 includes, for example, a tank body 71 into which the wastewater 1 flows from the primary sedimentation tank 10, and one or more membrane carriers 72 into which the air 2 supplied by the air supply device 80 is supplied. have The amount of air supplied by the air supply device 80 is smaller than the amount of air supplied by the air supply device described in FIGS.

The membrane carrier 72 is a tubular membrane carrier that molecularly diffuses the air supplied by the air supplier 80 into the reaction vessel 70 through a plurality of holes. Specifically, the membrane carrier 72 is a hydrophobic hollow fiber membrane, for example, a Teflon (registered trademark) membrane. The membrane carrier 72 is, for example, a tubular membrane whose axial direction extends in the vertical direction (the height direction of the reaction vessel 70). A large number of fine pores (for example, pores of about 0.1 micron) are present on the surface of the membrane carrier 72 . Air molecularly diffuses into the reaction chamber 70 through these fine holes.

A case where four membrane carriers 72 are arranged in the horizontal direction in the reaction vessel 70 will be described below, but the number of membrane carriers 72 other than four may be arranged in the reaction vessel 70. There may be. Further, hereinafter, the case where the air 2 supplied from the air supplier 80 is supplied from the vertically downward direction to the vertically upward direction inside the membrane carrier 72 will be described. 2 may be supplied from the vertical upward direction to the vertical downward direction inside the membrane carrier 72 . Further, the membrane carrier 72 may be, for example, U-shaped with both ends facing vertically upward. Further, the membrane carrier 72 may be, for example, U-shaped with both ends facing vertically downward.

Then, as shown in FIG. 4A, the membrane carrier 72 emits the air 2 supplied from the air supplier 80 toward the outside (inside the reaction vessel 70) from a plurality of holes on the surface (molecular diffusion). do. As a result, a biofilm containing aerobic bacteria (hereinafter referred to as biofilm R1) is formed on the outer circumference of the membrane carrier 72 by molecularly diffusing air into the reaction vessel 70 through the plurality of holes. This biofilm is a biofilm that biologically treats contaminants with aerobic bacteria. For example, as shown in FIG. 4(B), on the surface (on the outer periphery) of the membrane carrier 72, activated sludge (aerobic microorganisms) present in the tank body 71 adheres to form a massive biofilm, which is a biofilm. R1 is formed.

That is, in the reaction tank 70 of the present embodiment, the biofilm R1 adhered to the surface of the membrane carrier 72 decomposes the organic matter contained in the wastewater 1 and proliferates.

In addition, in order to prevent the biofilm R1 from peeling off due to the generation of air bubbles from the pores on the surface of the membrane carrier 72, the air 2 is released from the inside of the membrane carrier 72 to the outside, and the pores on the surface are used as the air-liquid interface. is performed by molecular diffusion from the gas phase side (inside the membrane carrier 72) to the liquid phase side (outside the membrane carrier 72). Therefore, the air supplier 80 preferably maintains the internal pressure of the membrane carrier 72 at a level that does not generate air bubbles from the pores on the surface (for example, a pressure equal to or lower than the water pressure). In this way, the pressure of the air supplied by the air supplier 80 can be made lower than the water pressure, so that the pressure of the air supplied by the air supplier 40 described in FIGS. 1 and 2 can be lowered. can. Therefore, the operating power of the air supplier 80 can be reduced compared to the operating power of the air supplier 40 . Return to FIG.

The reaction tank 70 discharges the waste water 1 (waste water) after the reaction with the biofilm R1 to the solid-liquid separation device 90. The solid-liquid separator 90 separates lumpy sludge containing biofilm R1 from the waste water discharged from the reaction tank 70 . The sludge to be separated contains various bacteria in addition to living or dead aerobic bacteria.

The solid-liquid separation device 90 only needs to have a sludge separation function, and may be, for example, a device including the separation membrane described in FIG. Further, the solid-liquid separator 90 may separate the sludge to be separated from the wastewater by gravity sedimentation, or may separate the sludge to be separated from the wastewater by sand filtration. In addition, the solid-liquid separation device 90 may separate the sludge to be separated from the wastewater using a carrier (so-called high-speed carrier filtration).

The organic wastewater treatment apparatus 100 further includes a stripping device 73 and a control device 74, for example.

The stripping device 73 is, for example, a device that strips the biofilm R1 adhering to the membrane carrier 72 from the membrane carrier 72 by vibrating the membrane carrier 72 .

The control device 74 is, for example, a computer having a CPU (Central Computing Unit), a memory, etc., and a program stored in a storage device (not shown) cooperates with the CPU to enable the peeling device 73 to remove biofilms. The timing of peeling R1 (hereinafter also referred to as peeling timing) is controlled.

In the following description, the biofilm R1 is peeled off by using the peeling device 73 in the reaction tank 70. Detachment may be performed (so-called membrane cleaning). In this case, the control device 74 may control the timing of jetting, for example.

That is, the reaction tank 70 in the present embodiment decomposes the organic substances contained in the wastewater 1 discharged from the primary sedimentation tank 10 to the reaction tank 70 by the biofilm R1 adhered to the membrane carrier 72, and takes in the organic substances. The aggregated biofilm R1 is intermittently separated from the membrane carrier 72, and the sludge containing the biofilm R1 is discharged to the solid-liquid separation device 90.

As a result, in the reaction tank 70 in the present embodiment, for example, during the time period when the biofilm R1 is decomposing organic matter (the time period when the biofilm R1 is not peeled off), the solid-liquid separator It is possible to suppress the amount of sludge discharged to 90. Therefore, in the reaction tank 70 , in this case, it is possible to discharge the wastewater 1 with low growth potential to the solid-liquid separation device 90 . Therefore, it becomes possible to prevent the proliferation of activated sludge in the solid-liquid separator 90 . Further, when the solid-liquid separation device 90 performs solid-liquid separation using a separation membrane, it is possible to prevent clogging of the separation membrane.

In addition, in the reaction tank 70 in the present embodiment, for example, even during the time period when the biofilm R1 is being peeled off, the sludge containing the biofilm R1 is discharged to the solid-liquid separation device 90, so that solid-liquid separation is performed. When the device 90 performs solid-liquid separation using a separation membrane, it is possible to prevent clogging of the separation membrane.

In addition, since the solid-liquid separation device 90 according to the present embodiment solid-liquid separates solid-liquid lumps of sludge from waste water, it is possible to easily dewater the separated sludge. Therefore, in the organic wastewater treatment apparatus 100 according to the present embodiment, it is possible to reduce the amount of flocculant that needs to be put in a dewatering machine or the like for dehydrating sludge, thereby reducing the cost required for dehydrating sludge. it becomes possible to

In addition, in the reaction vessel 70 of the present embodiment, by using the tubular membrane carrier 72, it is possible to increase the surface area compared to the case of using a membrane carrier having a shape other than tubular. Therefore, in the organic wastewater treatment apparatus 100 of the present embodiment, it is possible to reduce the volume of reaction between the activated sludge (aerobic microorganisms) and the organic matter, and it is possible to reduce the size of the reaction tank 70. . Specifically, in the organic wastewater treatment apparatus 100, for example, the vertical height (water depth) of the reaction tank 70 can be reduced.

Further, since the air supplier 80 according to the present embodiment can keep the pressure inside the membrane carrier 72 at a level that does not generate air bubbles from the pores on the surface, for example, the air supplier 40 described in FIG. It is possible to suppress the power associated with the supply of the air 2 more than when is used.

In addition, in the reaction tank 70 of the present embodiment, as shown in FIG. It becomes possible to form each of the anaerobic layers R3 from the surface of the membrane carrier 72 toward the liquid phase side. That is, in this case, between the two membrane carriers 72, as shown in FIG. be. Therefore, in the reaction tank 70, for example, ammonia contained in the wastewater 1 can be nitrified by the nitrification action in the aerobic layer R1. Then, in the anoxic layer R2 and the anaerobic layer R3, nitrogen contained in the wastewater 1 (for example, nitrite nitrogen) can be removed (denitrified) by a denitrification reaction.

In addition, in the reaction tank 70 of the present embodiment, the biofilm R1 adhered to the membrane carrier 72 is treated with organic matter. There is no need to maintain the concentration of activated sludge at a constant level. Therefore, in the organic wastewater treatment apparatus 100 of the present embodiment, for example, like the organic wastewater treatment apparatus 900 described in FIG. no need to send it back to As a result, in the organic wastewater treatment apparatus 100, for example, it is possible to substantially omit equipment necessary for returning sludge. If the sludge is returned to the reaction tank 70 , the returned sludge grows as activated sludge in the reaction tank 70 . When this multiplied activated sludge is discharged to the solid-liquid separation device 90, since this activated sludge is not lumpy, the dewaterability of the sludge is the same as that in the organic wastewater treatment device described with reference to FIG. It's going to be about. However, in the present embodiment, since it is not necessary to substantially return the sludge, only the stripped sludge (lump) of the biofilm R1 is discharged to the solid-liquid separation device 90, and the solid-liquid separation device 90 The dewaterability of the separated excess sludge can be improved.

It is not necessary to substantially return the sludge from the solid-liquid separation device 90 to the reaction tank 70 (in other words, the sludge is not substantially returned), as long as it does not deviate from the gist of the present invention. indicates that the sludge is allowed to be returned. Specifically, if the dewaterability of the sludge separated in the solid-liquid separation device 90 can be maintained in a state higher than the dewaterability of the sludge in the organic wastewater treatment device described in FIG. Sludge may be returned to the reaction tank 70 . When such return is performed, the amount of sludge returned (return time) in the organic wastewater treatment apparatus described in FIG. 2 is reduced (shortened).

In addition, in the organic wastewater treatment apparatus 900 (membrane separation activated sludge method) described in FIG. Liquor Suspended Solids) is required. However, in the reaction tank 70 of the present embodiment, since various biological treatments proceed with the biofilm attached to the surface of the membrane carrier 72, the MLSS concentration can be lowered compared to the membrane separation activated sludge method, and the solid The amount of sludge that flows into the liquid separator 90 and clogs the solid-liquid separation 80 can be minimized.

Further, instead of air, a gas having a higher oxygen concentration than air may be supplied to the membrane carrier 72 from the air supply device 80 in the present embodiment. As a result, in the reaction tank 70, the number of membrane carriers 72 that need to be provided in the reaction tank 70 can be reduced compared to the case where the air 2 is supplied to the membrane carriers 72 from the air supplier 80. become.

Further, in the reaction tank 70 of the present embodiment, the oxygen supplied to the membrane carrier 72 may be, for example, oxygen obtained by water electrolysis using renewable energy. For example, oxygen obtained by electrolyzing water using electric energy generated by using waste heat in sludge incineration may be used. In this power generation, for example, various power generation technologies such as organic Rankine cycle (ORC) can be used.

[Effects of the first embodiment]
Next, effects of the first embodiment will be described. 6 to 8 are diagrams for explaining the effects of the first embodiment.

First, the relationship between the separation interval of the biofilm R1 from the membrane carrier 72 and the organic matter removal rate in the reaction tank 70 will be described. FIG. 6 is a graph showing the relationship between the detachment interval of biofilm R1 and the removal rate of organic matter. The horizontal axis in the graph shown in FIG. 6 indicates the separation interval of the biofilm R1 (hereinafter simply referred to as the separation interval), and the vertical axis in the graph shown in FIG. (also called removal rate).

The graph shown in FIG. 6 indicates that the removal rate increases until the separation interval reaches around 24 (h), and further, the removal rate decreases as the separation interval increases from around 24 (h). Further, the graph shown in FIG. 6 indicates that the removal rate is about 88 (%) when the peeling interval is around 24 (h), and the peeling interval is around 12 (h) or 48 ( h) indicates that the removal rate is about 80 (%).

That is, the graph shown in FIG. 6 shows that, for example, when the separation interval is 12 (h) or more and 48 (h) or less, the removal rate can be maintained at 80 (%) or more, and the solid-liquid separation This indicates that it is possible to suppress the organic matter discharged to the device 90 to 20(%) or less.

On the other hand, the graph shown in FIG. 6 indicates that, for example, when the separation interval is 48 (h) or more, the removal rate decreases. When the thickness of the biofilm R1, which is a lump of sludge, reaches a predetermined thickness or more, the membrane carrier 72 side of the biofilm R1 (the portion that can directly receive the supply of oxygen from the membrane carrier 72) This is because the wastewater 1 is not sufficiently supplied, and the removal of organic matter is not efficiently performed.

Therefore, the control device 74 controls the biofilm R1 such that the separation interval is 12 (h) or more and 48 (h) or less, that is, the biofilm R1 is maintained at a removal rate of 80 (%) or more. may control the peeling timing of the . Specifically, the control device 74 may control the peeling timing of the biofilm R1 so that the peeling interval is 24 (h) or 48 (h), for example. Hereinafter, a case where the solid-liquid separator 90 performs solid-liquid separation using a separation membrane will be described as an example.

Next, the relationship between the detachment interval of the biofilm R1 and the flux in the solid-liquid separator 90 (hereinafter also referred to as flux) will be described. FIG. 7 is a graph showing the relationship between the biofilm R1 detachment interval and the flux in the solid-liquid separator 90. As shown in FIG. The horizontal axis in the graph shown in FIG. 7 indicates the peeling interval of the biofilm R1, and the vertical axis in the graph shown in FIG. (%) shows the flux of the solid-liquid separator 90.

The graph shown in FIG. 7 indicates that the flux increases until the separation interval reaches around 24 (h). Moreover, the graph shown in FIG. 7 indicates that the flux becomes almost 100(%) when the separation interval is 24(h) or more.

That is, the graph shown in FIG. 7 shows that, for example, when the separation interval is 24 (h) or more, it is possible to form a sufficiently large biofilm R1 on the membrane carrier 72, and the solid-liquid separation device 90 Since it becomes possible to suppress the occurrence of clogging, it is possible to keep the flux at a high level.

On the other hand, the graph shown in FIG. 7 shows that, for example, when the peeling time is 24 (h) or less, the biofilm R1 that is not large enough is discharged to the solid-liquid separator 90, so the solid-liquid separator Clogging occurs at 90, indicating a drop in flux.

Therefore, the control device 74 controls the peeling timing of the biofilm R1, for example, so that the peeling interval is 24 (h) or more, that is, so that the flux close to 100 (%) is maintained. you can

Further, the control device 74 controls the peeling timing of the biofilm R1, for example, so that the amount of substrates such as organic substances discharged from the reaction tank 70 to the solid-liquid separation device 90 satisfies a predetermined condition. good. Specifically, the control device 74 controls, for example, the amount of substrate discharged from the reaction tank 70 to the solid-liquid separation device 90 (that is, the amount of substrate in the waste water) is the amount of waste water flowing into the reaction tank 70 from the primary sedimentation tank 10 . The peeling timing of the biofilm R1 may be controlled so that the amount of the substrate is less than a predetermined ratio, preferably about 1/5.

Furthermore, the control device 74 is arranged so that, for example, the return sludge from the solid-liquid separation device 90 to the reaction tank 70 does not need to be returned, that is, the control device 74 controls, for example, the necessary amount of activated sludge by increasing the activated sludge. The separation timing of the biofilm R1 may be controlled so that the sludge is maintained in the reaction tank 70.

Next, the relationship between the biofilm R1 separation interval and the water content of the sludge (hereinafter also referred to as dewatered cake) after the sludge containing the separated biofilm R1 is dehydrated with a dehydrator will be described. FIG. 8 is a graph showing the relationship between the detachment interval of biofilm R1 and the moisture content of the dehydrated cake. The horizontal axis in the graph shown in FIG. 8 indicates the peeling interval of the biofilm R1, and the vertical axis in the graph shown in FIG. there is

The graph shown in FIG. 8 shows that the moisture content decreases as the separation interval increases. Moreover, the graph shown in FIG. 8 shows that when the peeling interval is longer than 24 (h), the moisture content is much lower than when the peeling time is shorter than 24 (h).

That is, the graph shown in FIG. 8 indicates that, for example, when the separation interval is 24 (h) or more, the moisture content of the dehydrated cake can be effectively reduced. The sludge containing exfoliated biofilm R1 obtained when the exfoliation interval is 24 (h) or more is dense. Dehydration of dense sludge in this manner yields sludge with a low moisture content.

Therefore, the control device 74 controls the peeling timing of the biofilm R1, for example, so that the peeling interval is 24 (h) or more, that is, the water content of the dehydrated cake is 75 (%) or less. can be

The control device 74 controls the peeling timing of the biofilm R1 according to all the graphs shown in FIGS. 6 to 8, for example, so that the peeling interval is 24 (h) or more and 48 (h) or less. It may be something to do.

As described above, in the organic wastewater treatment apparatus 100 according to the present embodiment, the biofilm R1 adhering to the membrane carrier 72 takes in organic matter and becomes agglomerate on the membrane carrier 72 . Therefore, in the organic wastewater treatment apparatus 100 , it is possible to discharge wastewater containing sludge (lump sludge) containing the biofilm R<b>1 in the form of blocks to the solid-liquid separator 90 . In addition, in the organic wastewater treatment apparatus 100, by forming the massive biofilm R1 on the membrane carrier 72, it is possible to reduce the amount of organic matter and activated sludge discharged from the reaction tank 70 to the solid-liquid separation apparatus 90. become. Therefore, in the organic wastewater treatment apparatus 100, it is possible to prevent the growth of activated sludge in the solid-liquid separation device 90 and the occurrence of clogging in the solid-liquid separation device 90, and the occurrence of clogging of the solid-liquid separation device 90. can be prevented.

In addition, in the organic wastewater treatment apparatus 100 according to the present embodiment, the massive biofilm R1 has a large particle size and tends to settle. Therefore, in the organic wastewater treatment apparatus 100, the sludge separated from the wastewater in the solid-liquid separator 90 can be easily dewatered, and the amount of flocculant that needs to be put in a dehydrator or the like can be reduced. . Therefore, in the organic wastewater treatment apparatus 100, for example, it is possible to reduce costs required for dehydration of sludge.

In the present embodiment, the sludge (separated sludge) contained in the wastewater discharged to the solid-liquid separator 90 is lumpy sludge. This blocky sludge is mainly composed of blocky biofilm R1, and this blocky sludge (hereinafter referred to as sludge of the present embodiment) is dense as described above and is easily dewatered. Then, this clumped sludge is separated by the solid-liquid separator 90 .

On the other hand, in order to maintain the performance of the reaction tank 50 of FIG. 2, the sludge separated from the separation membrane 53 of the reaction tank 50 of FIG. The body is the subject. Such sludge is dispersed and difficult to dewater.

Thus, the main sludge of the present embodiment and the main sludge of FIG. 2 (in other words, the sludge to be dewatered (separated)) are different. In order to achieve the desired moisture content, the amount of flocculant added can be reduced in this embodiment compared to the amount of flocculant added when dewatering the sludge in FIG.

By subjecting sludge, which is easily dewatered, to solid-liquid separation as in this embodiment, the amount of coagulant added can be reduced, and running costs can be suppressed.

In addition, for example, in the biofilm stripping performed in equipment that performs trickling filters, etc., the stripping interval is several weeks or more, so activated sludge with low strength (soft activated sludge) is stripped. Therefore, the moisture content of the dewatered cake produced from the separated activated sludge is approximately the same as that of the dehydrated cake produced from ordinary activated sludge.

In contrast, in the present invention, for example, by setting the peeling interval to about 24 (h) to 48 (h), a biofilm capable of producing a dehydrated cake with a low moisture content (biofilm peeled from the membrane carrier 72 R1) can be obtained.

In addition, in the organic wastewater treatment apparatus 100 in the first embodiment, for example, instead of the primary sedimentation tank 10, a solid-liquid separation apparatus (not shown) that performs high-speed filtration may be used. As a result, in the organic wastewater treatment apparatus 100, the amount of organic substances (for example, solid organic substances) supplied to the reaction tank 70 can be further suppressed, and the decomposition of the organic substances in the membrane carrier 72 can be made more efficient. It becomes possible to go to

[Organic wastewater treatment apparatus 100 in the first modification]
Next, the configuration of the organic wastewater treatment apparatus 100 in the first modification will be described. FIG. 9 is a diagram illustrating the configuration of the reaction vessel 70 in the first modified example. 10 and 11 are diagrams for explaining the configuration of the membrane carrier 72 in the first modified example.

[Peeling Device 73 and Control Device 74 in First Modification]
First, the peeling device 73 and the control device 74 in the first modified example will be described. The peeling device 73 in the first modified example peels the biofilm R1 by supplying gas such as air (hereinafter also simply referred to as air). Then, the control device 74 in the first modification controls, for example, the timing at which the peeling device 73 supplies air.

The peeling device 73, as shown in FIG. 9, has an air supply device 73a such as a compressor that compresses air taken in from the outside to generate compressed air (not shown), and an air supply device 73a. and an air tank 73b for storing compressed air.

Then, the control device 74 controls the supply (jetting) of the compressed air stored in the air tank 73b to the reaction tank 70, for example.

Specifically, for example, when it is time to peel off the biofilm R1, the control device 74 supplies the compressed air stored in the air tank 73b to a plurality of locations in the reaction tank 70 via the line L3. Biofilm R1 is stripped from membrane carrier 72 . The line L3 is, for example, a pipe that connects the air tank 73b and multiple locations in the reaction tank 70 . In addition, the control device 74 controls the separation interval of the biofilm R1 to be 24 (h) or longer, for example, as described with reference to FIG. 6 and the like.

Note that, as shown in FIG. 9, the control device 74 controls, for example, the generation timing of the compressed air by the air supplier 73a (compressed air for the air tank 73b) so that the pressure in the air tank 73b is maintained within a certain range. supply timing) may be controlled.

In addition to controlling the stripping device 73, for example, the control device 74 controls the amount of air 2 supplied by the air supplier 80 so that the amount of air 2 supplied to the membrane carrier 72 is constant. may be

Specifically, the control device 74 controls, for example, a measuring instrument (Fig. (not shown). The controller 74 may control the amount of air 2 supplied from the air supplier 80 to the membrane carrier 72, for example, according to the acquired measurement value. In the following description, it is assumed that the controller 74 controls the amount of air 2 supplied by the air supplier 80 .

In addition, although the example shown in FIG. 9 shows the case where compressed air is supplied between the membrane carriers 72, the compressed air may be supplied, for example, to the lower ends or below the membrane carriers 72. good.

[Specific Example of Membrane Carrier 72 in First Modification]
Next, the configuration of the membrane carrier 72 in the first modified example will be described.

In the reaction vessel 70 in the first modified example, as shown in FIGS. 9 and 10, for example, a unit UN1 is formed by bundling a plurality of membrane carriers 72. As a result, in the reaction tank 70 in the first modified example, for example, the number of pipes constituting the line L1 for supplying the air 2 to each membrane carrier 72 and the line L2 for discharging the air 2 from each membrane carrier 72 It is possible to reduce the number of pipes that make up the

Specifically, the example shown in FIG. 9 shows a case where four units UN1 formed by bundling four membrane carriers 72 are arranged in the reaction vessel 70 . A case where four membrane carriers 72 constitute a single unit UN1 will be described below, but the number of membrane carriers 72 other than four may constitute a single unit UN1. .

The plurality of membrane carriers 72 forming a single unit UN1 (hereinafter also simply referred to as the plurality of membrane carriers 72) are, as shown in FIG. For example, it has a first mold portion 72a formed by molding with a resin or the like, and a second mold portion 72b formed by molding the upper end portions 72d of each of the plurality of film carriers 72 with resin or the like. . That is, the plurality of film carriers 72 form a single unit UN1, for example, by molding the lower end portion 72c and the upper end portion 72d of each film carrier 72 .

The first mold portion 72a has, for example, a first air hole 72a1 for introducing the air 2 supplied from the air supplier 80 through the line L1 into the first mold portion 72a. The line L1 is, for example, a pipe that connects the air supplier 80 and the first air holes 72a1 in each of the plurality of units UN1, as shown in FIGS. Then, the air 2 introduced into the inside of the first mold portion 72a through the air holes 72a1 is supplied to the inside of each of the plurality of membrane carriers 72 from the respective lower end portions 72c of the plurality of membrane carriers 72, for example.

In addition, the second mold portion 72b has, for example, a second air hole 72b1 for discharging the air 2 inside the second mold portion 72b to the outside via the line L2. The line L2 is, for example, a pipe that connects the second air hole 72b1 in each of the plurality of units UN1 to the outside, as shown in FIGS. That is, the second air holes 72b1, for example, discharge the air 2 discharged into the second mold portion 72b from the upper end portions 72d of the plurality of film carriers 72 to the outside.

Specifically, the air 2 supplied (pressurized) into the first mold portion 72a via the line L1 and the first air holes 72a1 is applied to each of the plurality of membrane carriers 72 as indicated by solid line arrows in FIG. supplied internally. At least a portion of the air 2 supplied to each membrane carrier 72 moves inside each membrane carrier 72 from the lower end 72c to the upper end 72d, as described with reference to FIG. The molecules diffuse into the reaction vessel 70 through a plurality of holes h1 (for example, holes of about 0.1 microns) provided in the membrane carrier 72 . Subsequently, the air 2 that has moved inside each film carrier 72 from the lower end portion 72c to the upper end portion 72d (the air 2 that has not been molecularly diffused into the reaction chamber 70) is discharged from the upper end portion 72d to the second mold portion, for example. 72b. After that, the air 2 supplied into the second mold portion 72b is discharged to the outside through, for example, the second air hole 72b1 and the line L2.

As described above, in the organic wastewater treatment apparatus 100 in the first modification, the air supplier 80 supplies air to the inside of the membrane carrier 72 from the lower end 72c (hereinafter simply referred to as the lower end) of the membrane carrier 72, for example. 2 (air 2 containing at least oxygen). Then, the membrane carrier 72 causes, for example, at least a part of the air 2 supplied from the lower end portion 72c to molecularly diffuse into the reaction vessel 70 through the plurality of holes h1, thereby dispersing the air 2 supplied from the lower end portion 72c. The air 2 that has not been molecularly diffused in the reaction tank 70 is discharged outside from the upper end portion 72d (hereinafter simply referred to as the upper end) of the membrane carrier 72 .

Although the membrane carrier 72 shown in FIG. 10 has a linear shape (I shape), it is not limited to this. Specifically, the membrane carrier 72 may have any shape, for example, in which the air 2 supplied from the lower end portion 72c is discharged from the upper end portion 72d. may have

In the membrane carrier 72 shown in FIG. 10, the air 2 is supplied (pressurized) into the membrane carrier 72 from the lower end 72c, and the air 2 in the membrane carrier 72 is discharged from the upper end 72d. It is not limited to this. Specifically, the membrane carrier 72 may, for example, supply the air 2 into the inside of the membrane carrier 72 from the upper end 72d and discharge the air 2 inside the membrane carrier 72 from the lower end 72c.

The amount of air 2 supplied to each of the plurality of membrane carriers 72 is, for example, the amount of air 2 molecularly diffused into the reaction vessel 70 through the plurality of holes h1 on the lower end portion 72c side and the amount of air 2 on the upper end portion 72d side. may be determined so that the amount of the air 2 molecularly diffused into the reaction vessel 70 from the hole h1 of is the same. That is, the amount of air 2 supplied to each of the plurality of membrane carriers 72 is determined, for example, so that the oxygen partial pressure at each position in each membrane carrier 72 is maximized (the same pressure as the atmospheric pressure). you can

Also, the line L1 may be provided with a filter (not shown) for removing fine particles (for example, dust, etc.) contained in the air 2 supplied from the air supplier 80, for example.

[Another specific example of the membrane carrier 72 in the first modification]
Next, another configuration of the membrane carrier 72 in the first modified example will be described.

In the reaction vessel 70 in the first modified example, as shown in FIG. 11, for example, both ends (hereinafter also referred to as both ends 72f) face downward (for example, vertically downward direction) in a U shape (hereinafter referred to as an inverted U). The membrane carrier 72 may be arranged to form a letter shape. That is, in the reaction vessel 70, as shown in FIG. 11, for example, the membrane carrier 72 may be arranged in a state in which at least one portion (hereinafter also referred to as a curved portion 72e) is curved. In the reaction tank 70, for example, the unit UN2 may be formed by bundling a plurality of membrane carriers 72 arranged to form an inverted U shape. A case where two membrane carriers 72 arranged to form an inverted U shape form a single unit UN2 will be described below. may constitute the unit UN2.

Specifically, the air 2 supplied (pressurized) into the inside of the first mold portion 72a from the air holes 72a1 is, for example, discharged from both ends 72f of the plurality of membrane carriers 72 to each of the plurality of membrane carriers 72. supplied inside the That is, each of the end portions 72f shown in FIG. 11 has the same function as the lower end portion 72c described in FIG. 10, for example.

More specifically, the air 2 supplied from the air supplier 80 into the first mold portion 72a via the line L1 and the first air holes 72a1 is, for example, applied to a plurality of membranes as indicated by solid line arrows in FIG. supplied to each of the carriers 72 . The air 2 supplied to each membrane carrier 72 moves inside each membrane carrier 72 from both end portions 72f to curved portions 72e, for example, in each membrane carrier 72 as described with reference to FIG. Molecules diffuse into the reaction chamber 70 through a plurality of holes h2 (for example, holes of about 0.1 micron) provided in portions positioned outside the first mold portion 72a and the second mold portion 72b. Subsequently, the air 2 that has moved inside each membrane carrier 72 from both end portions 72f to the curved portion 72e (the air 2 that has not been molecularly diffused into the reaction vessel 70) is, for example, the curved portion 72e of each membrane carrier 72. is supplied into the second mold portion 72b from a plurality of holes h3 provided in the second mold portion 72b. After that, the air 2 supplied into the second mold portion 72b is discharged to the outside through, for example, the second air hole 72b1 and the line L2. That is, the plurality of holes h3 provided in the curved portion 72e shown in FIG. 11 have the same function as the upper end portion 72d described in FIG. 10, for example.

Thus, in the organic wastewater treatment apparatus 100 according to the first modification, the membrane carrier 72 has, for example, curved portions 72e that curve the membrane carrier 72 so that both ends 72f of the membrane carrier 72 face downward. have Then, the air supplier 80 supplies air 2 (air 2 containing at least oxygen) into the inside of the membrane carrier 72 from, for example, both ends 72f of the membrane carrier 72 (in other words, each of the lower ends of the membrane carrier 72). do. Furthermore, the membrane carrier 72 allows, for example, at least part of the air 2 supplied from at least one of both ends of the membrane carrier 72 to flow through the plurality of holes h2 (hereinafter also referred to as the plurality of first holes) into the reaction tank. The air 2 that has molecularly diffused into the membrane carrier 70 and has not been molecularly diffused into the reaction vessel 70 out of the air 2 that has been supplied from at least one of both ends of the membrane carrier 72 is removed from the curved surface positioned above the plurality of holes h2. It is discharged to the outside through a plurality of holes h3 (hereinafter also referred to as a plurality of second holes) provided in the portion 72e (in other words, the upper end of the membrane carrier 72).

11 is discharged into the second mold portion 72b through a plurality of holes h3 provided in the curved portion 72e, unlike the case of the film carrier 72 shown in FIG. be. Therefore, in the membrane carrier 72 shown in FIG. 11, the pressure loss associated with the discharge of the air 2 is greater than in the case of the membrane carrier 72 shown in FIG. Therefore, the membrane carrier 72 shown in FIG. 11 can increase the amount of air 2 supplied into the reaction chamber 70 by molecular diffusion, compared to the membrane carrier 72 shown in FIG.

1: waste water 2: air 10: primary sedimentation tank 20: reaction tank 21: tank body 22: air supply pipe 30: final sedimentation tank 40: air supply device 50: solid-liquid separation tank 51: tank body 52: air supply pipe 53 : Separation membrane 60: Air supplier 70: Reaction tank 71: Tank body 72: Membrane carrier 72a: First mold part 72a1: First air hole 72b: Second mold part 72b1: Second air hole 72c: Lower end part 72d: Upper end portion 72e: Curved portion 72f: Both ends 73: Peeling device 73a: Air supplier 73b: Air tank 74: Control device 80: Air supplier 90: Solid-liquid separator 100: Organic wastewater treatment device 800: Organic Wastewater treatment device 900: organic wastewater treatment device h1: hole h2: hole h3: hole L1: line L2: line L3: line R1: biofilm (aerobic layer)
R2: Anoxic layer R3: Anaerobic layer UN1: Unit UN2: Unit

Claims

A method for treating organic wastewater in an organic wastewater treatment apparatus, comprising:
The organic wastewater treatment apparatus includes a reaction tank for biologically treating contaminants contained in the organic wastewater, a solid-liquid separation device for separating sludge from the wastewater discharged from the reaction tank, and the reaction a supplier for supplying at least oxygen to the tank;
The reaction vessel has a tubular membrane carrier that molecularly diffuses the oxygen supplied by the supply device into the reaction vessel through a plurality of holes,
the membrane carrier forms a biofilm containing aerobic bacteria on the outer circumference of the membrane carrier by molecularly diffusing the oxygen into the reaction vessel through the plurality of pores;
The biofilm is a biofilm that performs biological treatment of the contaminants with the aerobic bacteria,
The solid-liquid separator separates the sludge containing the biofilm from the waste water.
The organic wastewater treatment apparatus further comprises a stripping device for stripping the biofilm formed on the membrane carrier from the membrane carrier, and a control device for controlling stripping of the biofilm by the stripping device. ,
2. The method of treating organic wastewater according to claim 1, wherein said control device exfoliates said biofilm at predetermined time intervals.
The method for treating organic wastewater according to claim 2, wherein the predetermined time interval is a time interval of 24 hours or more.
The organic wastewater treatment apparatus further comprises a stripping device for stripping the biofilm from the membrane carrier, and a control device for controlling stripping of the biofilm by the stripping device,
The control device controls the timing at which the biofilm is stripped so that the amount of substrate in the waste water is equal to or less than a predetermined ratio of the amount of substrate in the waste water flowing into the reaction tank. 2. The method for treating organic wastewater according to 1.
The method for treating organic wastewater according to claim 4, wherein the predetermined ratio is 1/5.
The organic wastewater treatment apparatus further comprises a stripping device for stripping the biofilm from the membrane carrier, and a control device for controlling stripping of the biofilm by the stripping device,
2. The organic wastewater according to claim 1, wherein the control device controls the timing at which the biofilm is removed so that the flux of the wastewater in the solid-liquid separation device is equal to or higher than a predetermined threshold value. Processing method.
The feeder presses the oxygen into the inside of the membrane carrier from the lower end of the membrane carrier,
The membrane carrier is
at least part of the oxygen injected from the lower end is molecularly diffused into the reaction vessel through the plurality of holes;
2. The method for treating organic wastewater according to claim 1, wherein oxygen that has not been molecularly diffused into said reaction tank among said oxygen injected from said lower end is discharged to the outside from said upper end of said membrane carrier.
The membrane carrier is arranged so that each of both ends faces downward,
the feeder presses the oxygen into the interior of the membrane carrier from each of the ends;
The membrane carrier is
At least part of the oxygen injected from at least one of the ends is molecularly diffused into the reaction vessel through a plurality of first holes among the plurality of holes, and injected from at least one of the ends. oxygen that has not been molecularly diffused into the reaction vessel out of the oxygen that has been added to the atmosphere through a plurality of second holes among the plurality of holes provided above the plurality of first holes. 2. The method of treating organic wastewater according to claim 1, wherein the organic wastewater is discharged.
a reaction tank for biologically treating contaminants contained in organic wastewater;
a solid-liquid separator for separating sludge from wastewater discharged from the reaction tank;
a feeder that supplies at least oxygen to the reaction vessel,
An apparatus for treating organic wastewater, wherein the reaction tank has a tubular membrane carrier for molecularly diffusing the oxygen supplied by the feeder into the reaction tank through a plurality of pores.