JPH11147098A - Anaerobic treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve intense treatment under high load and to reduce the surface contamination of a membrane under an anaerobic condition while efficiently washing the surface of the membrane. SOLUTION: An anaerobic reaction soln. is subjected to solid-liquid separation in a hermetically closed solid-liquid separation tank 2 in which a separation membrane 3 is arranged in an immersed state. The anaerobic reaction soln. and digestion gas are circulated between an anaerobic reaction tank 1 and the solid-liquid separation tank 2. At a time of membrane treatment, the digestion gas is diffused from an air diffusion means 4 to prevent the contamination of the membrane and, at a time of chemical washing, air is diffused from the air diffusion means 4 to enhance washing effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anaerobic treatment apparatus, and more particularly to an anaerobic treatment apparatus using a membrane immersion type solid-liquid separation tank as a solid-liquid separation means for anaerobic treatment.

[0002]

2. Description of the Related Art In the anaerobic treatment of organic wastewater, the amount of anaerobic sludge held in an anaerobic reaction tank affects the treatment performance including load. Therefore, as a technology for maintaining sludge at a high concentration and performing high-load and high-efficiency treatment, UASB (U.
pflow Anaerobic Sludge Bl
Aquet (upflow anaerobic sludge bed) system, fluidized bed system in which sludge adheres to the surface of a fluidized carrier or a filler in a reaction tank at a high concentration or fixed bed system has been developed and put into practical use.

However, in order to grow anaerobic sludge in the form of granules or to attach and grow high-concentration sludge on the surface of carriers and fillers, it is necessary to maintain operating conditions including control of wastewater and adjustment of load. Advanced technology is required for management. Further, fluctuations in load and amount of wastewater may cause granulated sludge or sludge adhering to a carrier or a filler to be disassembled or separated, and may flow out into treated water.

[0004] Therefore, the formation of granular sludge and the use of sludge adhering to a carrier or a filler do not require storage of 20 sludge in the reaction tank.
If a technology capable of maintaining a high-concentration sludge amount of 000 mg / L or more in a dispersed and floating state can be established, operation management becomes very easy, and anaerobic treatment corresponding to a high load is performed without requiring advanced technology. And the field of application of anaerobic treatment can be expanded.

Means for holding high-concentration sludge in a reaction tank without using granular sludge or sludge attached to a carrier or a filler include solid-liquid separation such as sedimentation separation, flotation separation, and centrifugation outside the reaction tank. There is a method of providing a means, separating the reaction liquid into solid and liquid, and returning the separated sludge to the reaction tank.However, since these solid and liquid separation means are basically open systems, anaerobic Difficult to apply to processing.

As a solution to this problem, a solid-liquid separation means using a membrane can be considered. For example, today, solid-liquid separation in activated sludge treatment requires MF inside or outside the aeration tank.
(Microfiltration) membrane and UF (ultrafiltration) membrane are immersed and installed to develop a very compact water treatment system that can obtain highly treated water regardless of sludge properties and is easy to manage. It is being put to practical use.

[0007]

However, in the membrane separation apparatus, since cleaning of the membrane is indispensable, in order to apply the membrane separation apparatus as a solid-liquid separation means for anaerobic treatment, the membrane must be cleaned under anaerobic conditions. It is necessary to develop a processing apparatus or a processing system capable of preventing contamination and effectively cleaning the film.

The present invention has been made in view of the above-mentioned conventional circumstances, and combines an anaerobic reaction tank and a membrane immersion type solid-liquid separation tank to remove granular sludge and sludge adhering to a carrier or a filler. An anaerobic treatment apparatus capable of performing advanced treatment under a high load treatment by holding sludge in a dispersed and suspended state in an anaerobic reaction tank at a high concentration of 20,000 mg / L or more without using it. It is an object of the present invention to provide an anaerobic treatment apparatus capable of reducing contamination of a film surface under anaerobic conditions and effectively cleaning the film surface.

[0009]

An anaerobic treatment apparatus according to the present invention comprises a closed solid-liquid separation tank in which an anaerobic reaction tank and a separation membrane are immersed, an anaerobic reaction tank, and a solid-liquid separation tank. A liquid circulation path for circulating an anaerobic reaction liquid between the anaerobic reaction tank and a gas circulation path for circulating an anaerobic reaction gas between the anaerobic reaction tank and the solid-liquid separation tank, and a gas discharge pipe provided in the anaerobic reaction tank An exhaust port provided in the solid-liquid separation tank, a transfer pipe for transferring the liquid in the solid-liquid separation tank to the anaerobic reaction tank, an air supply pipe for supplying air to the solid-liquid separation tank, and a liquid supplied to the solid-liquid separation tank A diffusing means for discharging the anaerobic reaction gas and air below the separation membrane.

[0010] In the anaerobic treatment apparatus of the present invention, the raw water is decomposed in the anaerobic reaction tank by the action of anaerobic sludge (anaerobic bacteria), and methane gas and carbon dioxide (C
O ₂ ) is produced. The anaerobic reaction liquid is introduced into a solid-liquid separation tank in which the membrane is immersed, and separated into sludge and treated water.

By employing the membrane separation means as the solid-liquid separation means, the anaerobic sludge concentration in the anaerobic reaction tank can be maintained at a high concentration of 20,000 mg / L or more. Load altitude processing becomes possible.
In addition, the membrane separation means eliminates the possibility of sludge flowing out with the treated water regardless of the properties of the anaerobic sludge (even if the sludge is in a dismantled state). It becomes unnecessary. Moreover, since the obtained treated water is the permeated water of the MF membrane and the UF membrane, it is possible to obtain advanced treated water containing no SS.

In addition, in the present invention, digestion gas can be diffused during membrane separation, so that the sludge layer that accumulates on the membrane surface while maintaining an anaerobic atmosphere is renewed, and the amount of permeated water (flux) decreases. Can be prevented.

Further, at the time of chemical cleaning, the cleaning effect can be enhanced by stirring the cleaning water by oxidizing the air.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a system diagram showing an embodiment of the anaerobic treatment apparatus of the present invention.

In FIG. 1, 1 is an anaerobic reaction tank, 2 is a membrane immersion type solid-liquid separation tank, and a separation membrane 3 is immersed in the tank.

The anaerobic reaction tank 1 is a floating anaerobic reaction tank using anaerobic bacteria in a floating state.
1 and anaerobic reaction gas generated by anaerobic treatment (digestion gas)
Is provided.

The membrane immersion type solid-liquid separation tank 2 is a sealed mixed liquid (anaerobic reaction liquid) from the anaerobic reaction tank 1 in a closed state.
Is transferred and circulated, and the MF membrane or U immersed and installed in the tank
Subjected to solid-liquid separation by the separation membrane 3 F film or the like, which was aspirated treated water in the treated water pump P ₁ extracted from the pipe 13, below the separation membrane 3 of the tank bottom is installed diffusing tubes 4 ing. From the air diffuser 4, the digestion gas introduction pipe 14 from the anaerobic reaction tank 1 is diffused by the diffusion blower B so that the digestion gas or air in the anaerobic reaction tank 1 can be diffused.
And the air introduction pipe 15 are connected. In addition, a return pipe 16 and an exhaust pipe 17 for returning the scattered digested gas to the anaerobic reaction tank 1 are provided above the membrane immersion type solid-liquid separation tank 2.

The liquid in the anaerobic reaction tank 1 is a circulation pump P ₂
Is introduced into the membrane immersion type solid-liquid separation tank 2 through a pipe 18 provided with a solid-liquid separation, and then returned to the anaerobic reaction tank 1 through a pipe 19. Moreover, the sludge mixture of the separation membrane in the membrane submerged solid-liquid separation tank 2 during chemical cleaning of 3 anaerobic reactor by a transfer pipe 20 and transfer pump P ₃ provided at the bottom of the membrane submerged solid-liquid separation tank 2 Transferred to tank 1.

Reference numeral 5 denotes a chemical storage tank for chemical cleaning of the separation membrane 3. The cleaning chemical is supplied to the membrane immersion type solid-liquid separation tank 2 from a pipe 21 provided with a chemical injection pump P ₄ , and the cleaning waste liquid is supplied to the pipe 2.
It is discharged out of the system from 2. Note that V ₁ , V ₂ , V ₃ , V ₄ ,
_{V 5, V 6, V 7} , V 8, V 9 are valves.

Next, an operation method of the anaerobic treatment device will be described.

[Normal operation: valves V ₁ , V ₂ , V ₄ , V ₅
Open, valve _{V 3, V 6, V 7} , V 8, V 9 closed] raw water piping 1
It is introduced into the anaerobic reactor 1 than 1, feed in the circulating pump P ₂ from the anaerobic reactor 1 anaerobic reactor mixture (anaerobic reaction) to the membrane submerged solid-liquid separation tank 2, the anaerobic The reaction solution is circulated through the anaerobic reaction tank 1, the pipe 18, the membrane immersion type solid-liquid separation tank 2, and the pipe 19. If the amount of the circulating liquid is small, the sludge concentration becomes too high due to membrane separation. Therefore, the amount of the circulating liquid is appropriately set so as to obtain a desired sludge concentration. Normally, this circulating fluid volume is more than twice the raw water inflow volume, especially 4 times.
It is preferably at least two times, especially 4 to 5 times.

In the membrane immersion type solid-liquid separation tank 2, the anaerobic reaction liquid is separated into solid and liquid by the separation membrane 3, the permeated liquid is sucked by the treatment water pump P ₁ , and is withdrawn from the pipe 13 as treatment water out of the system. .

[0024] As the conditions for the membrane separation in the membrane submerged solid-liquid separation tank 2, for example, if the separation performance as a separation membrane 3 was used hollow fiber MF membranes around 0.1 [mu] m, the treated water pump P ₁ The suction pressure (pressure difference between the raw water side and the permeated water side of the membrane) is preferably within 50 KPa, and the permeated water amount (flux) of the membrane is 0.3 to 0.9 m ^3.
/ M ² / day is appropriate. If the flux is excessively large, clogging of the membrane proceeds rapidly, and the pressure loss of the membrane increases early. On the other hand, if the flux is excessively small, the amount of treated water obtained is small, and the treatment efficiency decreases, which is not preferable.

During the suction of the treated water, the anaerobic reaction tank 1
Gas from the pipe 14 and diffuser blower B
The gas is diffused from the diffusion pipe 4 at the bottom of the membrane-immersion type solid-liquid separation tank 2, and the diffused exhaust gas is returned to the anaerobic reaction tank 1 through the pipe 16.

By diffusing the digestion gas in this way, contamination of the membrane surface of the separation membrane 3 immersed and arranged in the membrane immersion type solid-liquid separation tank 2 is reduced, and the flux is reduced due to an increase in the pressure loss of the membrane. Can be prevented.

That is, the gaseous gas is diffused from the lower portion of the separation membrane 3 as described above, whereby a water flow is generated on the membrane surface based on the upward flow of bubbles, and the sludge layer (gel layer) accumulated on the membrane surface is renewed. Therefore, a decrease in flux can be suppressed.
In addition, since the digestion gas is used for the air diffusion instead of the air, the anaerobic atmosphere is maintained even in the membrane immersion type solid-liquid separation tank 2 and the anaerobic reaction is performed, so that the capacity of the anaerobic reaction tank 1 is reduced. You can also. Thus, the diffused exhaust gas
Since it is returned to the anaerobic reaction layer 1 and circulated without being released from the membrane immersion type solid-liquid separation tank 2, the digestion gas supplied to the membrane immersion type solid-liquid separation tank 2 does not run out, and The surface flow velocity can be maintained.

If the amount of the digested gas diffused is small, the renewal of the gel layer on the membrane surface becomes insufficient and the pressure loss increases. If the amount of the digested gas diffused is too large, the separation membrane 3 immersed in the membrane immersion type solid-liquid separation tank 2 may vibrate or the adjacently arranged membranes may be rubbed against each other to cause physical damage. The gas diffusion amount of the digestion gas is preferably about ^{20 to} 100 m ³ / m ² / hr per horizontal sectional area of the lower part of the membrane immersion type solid-liquid separation tank 2.

If the amount of digestion gas generated in the anaerobic treatment is more than necessary, the valve V ₇ is opened appropriately and the digestion gas is discharged from the pipe 12. Since the surplus digestive gas is mainly composed of methane, it is stored in a gas tank or the like and is effectively used as fuel.

From the viewpoint of preventing the pressure loss of the separation membrane 3 from increasing, it is preferable that the treated water pump P ₁ is set to an intermittent operation in which the operation for a predetermined time and the operation stop for a predetermined time are alternately repeated. The time setting for the intermittent operation varies depending on the properties and concentration of the anaerobic sludge, the operation flux, the performance of the separation membrane, and the like.
The operation can be intermittent operation for seconds to 5 minutes. In addition, means for injecting treated water or working water from the permeated water side of the separation membrane when the operation of the treated water pump is stopped is also effective in preventing an increase in pressure loss.

[Before chemical cleaning: valves V ₃ , V ₇ , V ₈ open,
Valve _{V 1, V 2, V 4} , V 5, V 6, V 9 closed] [during chemical cleaning: valve V _6, V _7, V ₈ open, valve V _1, V
_{2, V 3, V 4,} V 5, V 9 closed] [after chemical washing: valve V _7, V _8, V ₉ open, the valve V _1, V
_{2, V 3, V 4,} V 5, when V ₆ closed] prolonged operation of the process water pump P ₁ continues, the separation membrane 3
The contaminants adhere to and accumulate on the film surface, and the flux decreases. Therefore, periodically or when the pressure loss of the separation membrane 3 becomes a predetermined value or more, the entire amount of the liquid in the membrane immersion type solid-liquid separation tank 2 is transferred to the anaerobic reaction tank 1, The cleaning agent in the chemical tank 5 is introduced into the membrane immersion type solid-liquid separation tank 2 by the injection pump P _4, and air is diffused from the diffuser pipe 4, and the chemical cleaning of the separation membrane 3 is performed under aeration and agitation.

The necessity or frequency of chemical cleaning depends on the operating conditions of the membrane immersion type solid-liquid separation tank 2, the concentration of anaerobic sludge, and the like. For example, when the hollow fiber MF membrane described above is used,
It is preferable to perform the process when the pressure loss of the separation membrane reaches 50 KPa. Usually, acids and alkalis are used for cleaning the separation membrane, but an oxidizing agent (chlorine, hydrogen peroxide, ozone, etc.) is effective for cleaning the separation membrane used for separating anaerobic sludge. The chemical cleaning is performed by using the oxidizing agent alone or by using the oxidizing agent and an acid, an alkali, a surfactant or the like in combination.

The reason why a small amount of an oxidizing agent such as sodium hypochlorite or hydrogen peroxide is effective for cleaning the separation membrane used in the anaerobic treatment is as follows.

In the separation membrane used for the anaerobic treatment, sludge and contaminants adhere to the membrane surface under a reducing atmosphere.
Therefore, by using a small amount of an oxidizing agent such as sodium hypochlorite or hydrogen peroxide, it is possible to neutralize the oxidation-reduction potential of the attached sludge or contaminant, and to promote the cleaning effect on the membrane surface. Anaerobic sludge is generally characterized by less accumulation of viscous substances than aerobic sludge represented by activated sludge.
When aerobic sludge containing a lot of viscous substances adheres to the membrane surface, it is necessary to solubilize or reduce the molecular weight of the viscous substances with high-concentration sodium hydroxide and high-concentration sodium hypochlorite or hydrogen peroxide. In the case of anaerobic sludge with a small amount of substance, a sufficient washing effect can be obtained by mixing a small amount of oxidizing agent with low-concentration caustic soda.

The chemical cleaning method varies depending on the operating conditions and the like. In the case of a hollow fiber MF membrane, caustic soda 0.5 to 4
% By weight, sodium hypochlorite (as available chlorine) 250 ~
Generally, a 500 mg / L mixed solution is used, and the separation membrane is immersed and washed in the mixed solution for 6 hours or more under air diffusion. If this method does not remove contaminants from the film, the concentration of caustic soda or sodium hypochlorite may be increased, or hydrochloric acid, sulfuric acid, or a surfactant may be used. Cleaning agents used (waste wash liquid) is, after appropriate neutralization treatment or reduction treatment or the like or discharging valve V ₉ to the outside of the system from the pipe 22 is opened, subjected to anaerobic treatment by mixing the raw water.

In the present invention, the chemical cleaning of the separation membrane can be performed under agitation by air diffusion from below the separation membrane, so that the contaminants adhering to the membrane surface can be efficiently removed and removed. , A good cleaning effect can be obtained. It is conceivable to use digestive gas for the aeration during this chemical cleaning, but it is preferable to perform the cleaning of the membrane used for separating anaerobic sludge in an oxidizing atmosphere as described below. Aeration is inappropriate.

When the digestion gas is diffused from the lower part of the separation membrane, the carbon dioxide contained in the digestion gas is absorbed by the cleaning agent caustic soda, and the alkalinity of the caustic soda is reduced. Therefore, it is necessary to increase the amount and concentration of caustic soda to be used, which is uneconomical. On the other hand, the content of carbon dioxide gas in ordinary air is much smaller than that of digestion gas, so that the effect of caustic soda is not impaired. Digestion gas may contain hydrogen sulfide, but when digestion gas containing hydrogen sulfide is used, it reacts with oxidizing agents such as sodium hypochlorite and hydrogen peroxide Effect is lost. Since membrane separation is performed under anaerobic conditions, contaminants of the membrane naturally adhere to the membrane surface under reducing conditions. By performing air aeration during film cleaning, the degree of reducibility of contaminants in the film is reduced, and the film is easily peeled.

In the present invention, if the amount of air diffused at the time of chemical cleaning is too small, the effect of improving the cleaning effect cannot be sufficiently obtained, and if it is too large, the air is diffused as in the case of the above-mentioned gas diffusion of digestive gas. In this case, a problem such as vibration of the separation membrane occurs, so that the amount of air diffused is 20 to 50 per horizontal sectional area of the membrane immersion type solid-liquid separation tank 2.
It is preferable to set about m ³ / m ² / hr. The diffused air is released from the pipe 17 to the outside of the system.

Generally, a plurality of membrane immersion type solid-liquid separation tanks are provided for one anaerobic reaction tank. Therefore, chemical cleaning of the membrane immersion type solid-liquid separation tank is performed sequentially, and chemical cleaning of the separation membrane is performed. The treated water can be stably obtained by extracting the treated water from the membrane-immersed solid-liquid separation tank other than the membrane-immersed solid-liquid separation tank in which the process is performed.

The anaerobic treatment apparatus shown in FIG. 1 is an embodiment of the present invention, and the present invention is not limited to the illustrated one as long as it does not exceed the gist.

For example, the anaerobic reaction tank 1 employs a complete mixing system or a floating system using ordinary floating sludge, or a combination of these systems with a UASB system, a fluidized bed system or a fixed bed system. There is no particular limitation on the driving method or the like.

The digestion gas generated in the anaerobic reaction tank 1 is directly extracted from the anaerobic reaction tank 1 and diffused from the diffuser pipe 4 of the membrane immersion type solid-liquid separation tank 2, and a separate gas holder is provided. The gas generated in the anaerobic reaction tank 1 may be received by a gas holder, and the gas may be sent from the gas holder to an air diffuser to diffuse air, and the diffused exhaust gas may be returned to the gas holder.

Further, the air diffusion pipes below the separation membrane may be provided separately for the gas diffusion and the gas diffusion, or may be used as shown in FIG.

Further, as shown in FIG. 1, the transfer pipe of the separated sludge of the membrane immersion type solid-liquid separation tank 2 may be provided independently of the circulation pipe 18 of the liquid in the anaerobic reaction tank 1. the system path 18A indicated by the broken line in FIG. 1, provided branched piping as 18B, it may be transported by using the circulation pump P ₂ through the circulation pipe 18.

[0045]

The present invention will be described more specifically with reference to the following examples.

Example 1 BO actually performing anaerobic treatment by the UASB method
A verification test of the effect of this method was performed using isomerized sugar production wastewater of D3500 to 5000 mg / L. The load per anaerobic reaction tank capacity of this actual device is 10 to 15 kg-
BOD / m ³ / day, the sludge in the reaction tank was in the form of granules having a particle size of 0.5 to 3.2 mm, and the sludge concentration was 15000 mg / L. The quality of the treated water is S
S200-360mg / L, BOD330-750mg
/ L.

The anaerobic reactor used in the demonstration test had a diameter of 30.
It is a closed tank having a height of 0 mm and a height of 1000 mm (effective volume: 50 L), and is a reaction tank of a mechanical stirring system using suspended sludge. A heater linked to a thermometer is installed in the reaction tank,
The temperature in the tank was adjusted to 37 ° C. as in the actual apparatus. Also, p
The pH of the solution in the tank was adjusted to around 7.2 as in the actual device by means of a caustic soda injecting device linked to the H meter. A circulation pump was installed in the anaerobic reaction tank, and the liquid in the tank was transferred from the anaerobic reaction tank to the membrane-immersion type solid-liquid separation tank and circulated. Further, the gas portion at the upper part of the reaction tank was connected to the upper part of the solid-liquid separation tank by piping, and the return liquid of the circulation pump was configured to flow down from the solid-liquid separation tank to the anaerobic reaction tank.

The membrane immersion type solid-liquid separation tank is a closed tank having a length of 500 mm, a width of 100 mm, and a height of 1000 mm (effective volume 25 L), and has an effective membrane area of 0.5 m ² manufactured by Mitsubishi Rayon Co., Ltd. One hollow fiber MF membrane for use (“Stellapore L”, separation performance: 0.1 μm, membrane material polyethylene) was installed.

At the bottom of the solid-liquid separation tank, an air diffuser was installed on the entire surface, and the horizontal sectional area of the solid-liquid separation tank was 30 m ³ / m ² / hr.
At 25 L / min corresponding to the above, a digestion gas was spouted from the gas part at the top of the anaerobic reaction tank. The exhaust gas was returned to the gas part of the anaerobic reaction tank through the connecting pipe at the top of the tank. During chemical cleaning of the hollow fiber membrane, air was blown from the air diffuser at 17 L / min corresponding to 20 m ³ / m ² / hr per horizontal sectional area of the solid-liquid separation tank, and exhaust air was discharged from the upper part of the tank. The permeated water from the hollow fiber membrane was drawn out by a treated water pump via a flow meter and a pressure gauge to obtain treated water. The treated water pump was operated for 8 minutes and intermittently operated for 2 minutes.

In the continuous operation, the granular sludge collected from the reaction tank of the actual apparatus is crushed to a particle diameter of 0.1 mm or less to produce suspended sludge in a dispersed state, and the sludge concentration is 30,000 mg / L, twice that of the actual apparatus. The mixture was concentrated by centrifugation and charged into an anaerobic reaction tank.

The raw water flow and the treated water flow are 300 L / da.
y, and the amount of circulating water from the anaerobic reaction tank to the membrane immersion type solid-liquid separation tank was set to 1200 L / day. BOD load per anaerobic reactor volume is 21-30kg-BOD
/ M ³ / day, and the flux of the hollow fiber membrane was 0.75 m ³ / m ² / day when the treated water pump was operating.

A continuous operation was performed for 30 days under these test equipment and operating conditions. The pressure loss of the hollow fiber membrane was 5 to 15 KPa in the initial operation, but after 25 days of continuous operation, the pressure loss of the hollow fiber membrane reached 50 KPa. Transfer the liquid to another tank,
1% by weight of sodium hydroxide and 5% sodium hypochlorite in the separation tank
The mixture was filled with a mixed solution of 00 mg / L (effective chlorine), and immersion cleaning was performed for 6 hours while air was diffused from an air diffuser at a lower portion of the separation tank. By this washing, the pressure loss of the hollow fiber membrane after restarting the operation was reduced to 7 KPa.

Table 1 shows the results of the verification test and the results of operation of the actual apparatus (usual UASB anaerobic treatment apparatus) during the same period.

[0054]

[Table 1]

As is clear from the results of the above-mentioned demonstration operation,
In the anaerobic treatment apparatus of the present invention, the BOD load is 21 to 30 k.
Even under a high load condition of g / m ³ / day, the sludge concentration in the reaction tank can be maintained at a high concentration of 30,000 mg / L or more, so that a high BOD of 32 to 110 mg / L (BOD removal rate of 97% or more) is obtained. Treated water can be obtained. In addition, since membrane separation was performed, SS of the treated water was below the detection lower limit.

[0056]

As described in detail above, according to the anaerobic treatment apparatus of the present invention, the anaerobic sludge concentration can be maintained at a high concentration of 20,000 mg / L or more, and as a result, high-load treatment can be performed. Become. Regardless of the properties of the anaerobic sludge, stable treatment can be performed, so that operation management and maintenance are facilitated. Since the treated water is the membrane permeated water, it is possible to obtain advanced treated water containing no SS. At the time of membrane separation treatment, membrane contamination can be prevented by digestion gas diffusion. At the time of membrane cleaning, a high cleaning effect can be obtained by air diffusion. Thus, an effective anaerobic treatment can be performed, and the treated water having good water quality can be stably obtained.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of an anaerobic treatment device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Anaerobic reaction tank 2 Membrane immersion type solid-liquid separation tank 3 Separation membrane 4 Aerator tube 5 Chemical storage tank P ₁ Treatment water pump P ₂ Circulation pump P ₃ Transfer pump P ₄ Chemical injection pump B Diffusion blower

Claims (1)

[Claims] 1. A liquid circulation path for circulating an anaerobic reaction liquid between a closed solid-liquid separation tank provided with an anaerobic reaction tank and a separation membrane immersed therein, and between the anaerobic reaction tank and the solid-liquid separation tank. A gas circulation path for circulating an anaerobic reaction gas between the anaerobic reaction tank and the solid-liquid separation tank, a gas discharge pipe provided in the anaerobic reaction tank, an exhaust port provided in the solid-liquid separation tank, and a solid-liquid The transfer pipe for transferring the liquid in the separation tank to the anaerobic reaction tank, the air supply pipe for supplying air to the solid-liquid separation tank, and the anaerobic reaction gas and air supplied to the solid-liquid separation tank are discharged below the separation membrane. An anaerobic reaction device, comprising: