JP2002205090A - Methane fermentation water treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide methane fermentation water treatment equipment which is capable of preventing release of gases, such as gaseous methane and toxic gases, within the system of the methane fermentation water treatment equipment to the outside of the system in exchanging a membrane separation unit. SOLUTION: This methane fermentation water treatment equipment has a methane fermenter 3 to which waste water is supplied and a membrane separator 1 which accepts the waste water supplied from the methane fermenter 3 and internally has the membrane separation unit 2 soaked in this waste water. A waste water connecting pipe 4 is disposed between the methane fermenter 3 and the membrane separator 1. The methane fermenter 3 and the membrane separator 1 having the membrane separation unit 2 are provided as separate units. As a result, the membrane separation unit 2 in the membrane separator 1 can be exchanged without releasing the gases in the methane fermenter 3 to the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a methane fermentation tank,
The present invention relates to a methane fermentation water treatment apparatus provided with a membrane separation tank and a wastewater connection pipe interposed between the methane fermentation tank and the membrane separation tank.

[0002]

2. Description of the Related Art A methane fermentation water treatment apparatus has been conventionally used as a methane fermentation water treatment apparatus for purifying wastewater containing high-concentration organic waste such as human waste, septic tank sludge, garbage, etc. by a methane fermentation method. It has been known.

[0003] Wastewater containing high-concentration organic waste is supplied to a methane fermentation tank, and the wastewater is methane-fermented by methane bacteria in the methane fermentation tank, and organic substances in the wastewater are converted into methane gas and removed. The wastewater that has been subjected to methane fermentation and mixed with solid and liquid to form a sludge is subjected to membrane separation by a membrane separation unit to be separated into solid and liquid. The permeate from the wastewater after the solid phase has been removed by membrane separation is sent to another treatment tank.

[0004]

As described above, wastewater containing high-concentration organic waste is sent to another treatment tank via a methane fermentation tank having a membrane separation unit.

[0005] In this case, the solid phase of the sludge-like wastewater obtained by methane fermentation is removed by a membrane separation unit.
This solid phase accumulates in the membrane separation unit. Therefore, replacement of the membrane separation unit is required.

[0006] When replacing the membrane separation unit in the methane fermentation tank, it is necessary to open the methane fermentation tank. However, when opening the methane fermentation tank, there is a problem that gases such as methane gas and toxic gas existing in the methane fermentation tank flow out of the methane fermentation tank.

Further, in the methane fermentation water treatment apparatus utilizing methane fermentation, it is necessary to supply wastewater for activating methane fermentation in the methane fermentation tank into the methane fermentation tank. This is often carried out by feeding wastewater in the lower part of the methane fermentation tank into the methane fermentation tank from a water pipe inserted into the lower part of the methane fermentation tank. However,
If the water pipe is clogged, there is a problem that the wastewater is not uniformly supplied into the methane fermentation tank.

When wastewater contains a large amount of lipids and proteins, biogas bubbles generated from the wastewater are less likely to burst, and scum is formed on the liquid surface of the wastewater.
When the scum formed in this way accumulates on the liquid surface of the wastewater, there is a problem that the flow of the wastewater in the methane fermentation tank is hindered by the scum.

[0009] The present invention has been made in view of such a point, and when the membrane separation unit is replaced, gas such as methane gas and toxic gas in the system of the methane fermentation water treatment apparatus is removed from the system. Of methane fermentation, and the wastewater can be supplied stably to the methane fermentation tank, and the scum generated in the methane fermentation tank can be removed to stabilize the efficiency of methane fermentation. It is an object of the present invention to provide a methane fermentation water treatment device that can be used.

[0010]

SUMMARY OF THE INVENTION The present invention provides a methane fermentation tank to which wastewater is supplied, a wastewater supplied from the methane fermentation tank, and a membrane separation unit having a membrane separation unit immersed in the wastewater. A methane fermentation water treatment device, comprising: a tank; and a wastewater connecting pipe interposed between the methane fermentation tank and the membrane separation tank.

According to the present invention, the methane fermentation tank and the membrane separation tank having the membrane separation unit inside are provided separately from each other. The membrane separation unit can be replaced without discharging the water to the outside of the water treatment system.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment of the present invention. Here, FIG. 1 is a configuration diagram showing a methane fermentation water treatment device.

In FIG. 1, the methane fermentation water treatment apparatus
A methane fermentation tank 3 to which wastewater is supplied, a membrane separation tank 1 which receives the wastewater supplied from the methane fermentation tank 3 and has a membrane separation unit 2 immersed in the wastewater therein;
Wastewater connection pipe 4 connecting methane fermentation tank 3 and membrane separation tank 1
And At the bottom of the membrane separation tank 1, a first wastewater return pipe 29a connected to the methane fermentation tank 3 is attached.

The end of the wastewater connecting pipe 4 on the side of the membrane separation tank 1 is disposed below the surface of the wastewater inside the membrane separation tank 1, and the methane fermentation tank 3 and the membrane separation tank 1 are provided with a methane fermentation tank. A gas holder 24 in which gases such as methane gas existing in the chamber 3 and in the membrane separation tank 1 are connected.

The gas holder 24 and the methane fermentation tank 3 are connected by a first gas transfer pipe 31a, and the gas holder 24 and the membrane separation tank 1 are connected by a second gas transfer pipe 31b. The transfer pipe 31b is provided with a gas valve 13 capable of adjusting a gas flow rate from the membrane separation tank 1 to the gas holder 24. Further, the membrane separation tank 1 is provided with a permeate transport pipe 30 for transporting the permeate of the wastewater after the membrane separation by the membrane separation unit 2.

Next, the operation of this embodiment having the above-described configuration will be described.

The wastewater supplied into the methane fermentation tank 3 is subjected to methane fermentation to remove organic matter, and the wastewater becomes sludge mixed with solid and liquid. The sludge-like wastewater is supplied to a membrane separation tank 1 provided separately from the methane fermentation tank 3 via a wastewater supply pipe 14, and the wastewater is separated by a membrane separation tank provided in the membrane separation tank 1. The unit 2 performs membrane separation and solid-liquid separation. When the wastewater is subjected to membrane separation by the membrane separation unit 2,
The solid phase in the wastewater is captured on the membrane separation unit 2, and the liquid phase is sent as a permeate through a permeate transport pipe 30 to another treatment tank. A part of the wastewater in the membrane separation tank 1 is returned to the methane fermentation tank 3 via the first wastewater return pipe 29a.
By returning the wastewater in the membrane separation tank 1 to the methane fermentation tank 3 in this manner, the concentration of suspended solids in the processing liquid in the methane fermentation tank 3 and the membrane separation tank 1 can be stably maintained.

Further, gases such as methane gas in the methane fermentation tank 3 are accumulated in the gas holder 24 via the first gas transfer pipe 31a. Gases such as methane gas in the membrane separation tank 1 are released by opening the gas valve 13 to the second gas.
It is accumulated in the gas holder 24 via the gas transfer pipe 31b,
In this way, gases in the methane fermentation tank 3 and the membrane separation tank 1 are sent to the gas holder 24.

During this time, the end of the wastewater connection pipe 4 on the side of the membrane separation tank 1 is disposed below the surface of the wastewater inside the membrane separation tank 1, so that the wastewater connection pipe 4 enters the membrane separation tank 1 via the wastewater connection pipe 4. The supplied wastewater is supplied to the membrane separation tank 1 without being released into the air.
Flows into the wastewater inside. Therefore, the wastewater is methane fermenter 3
Is supplied to the membrane separation tank 1 via the wastewater connection pipe 4 from the methane fermentation tank 3, the wastewater connection pipe 4, and the membrane separation tank 1. In such a closed system, the gas such as methane gas mixed into the wastewater connection pipe 4 is disposed such that the end of the wastewater connection pipe 4 on the membrane separation tank 1 side is located above the water surface of the wastewater inside the membrane separation tank 1. As a result, the wastewater is less likely to flow into the membrane separation tank 1 than when the wastewater is released into the air.

As described above, according to the present embodiment, the methane fermentation tank 3 in which methane fermentation is performed, and the membrane separation tank 2 in which the membrane separation unit 2 in which the methane fermented wastewater is separated. Are provided separately from each other, so that only the membrane separation unit 2 can be replaced without causing the gases in the methane fermentation tank 3 to flow out of the methane fermentation tank 3. Further, since the end of the wastewater connection pipe 4 on the side of the membrane separation tank 1 is disposed below the level of the wastewater inside the membrane separation tank 1, the wastewater flows from the methane fermentation tank 3 through the wastewater connection pipe 4 through the membrane. The system supplied to the separation tank 1 is a closed system, whereby the gas in the methane fermentation tank 3 is
From the wastewater into the membrane separation tank 1 can be prevented.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 2 is a diagram showing a second embodiment of the present invention. Here, FIG. 2 is a configuration diagram showing a methane fermentation water treatment device.

In the second embodiment shown in FIG. 2, a membrane drawing water tank 5 is connected to the membrane separation tank 1, and the membrane separation unit 2 in the membrane separation tank 1 is moved into the membrane drawing water tank 5. This embodiment is different from the first embodiment shown in FIG. 1 only in that the present embodiment is different from the first embodiment.
In FIG. 2, the same parts as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted. The inside of the water tank 5 is filled with water.

In FIG. 2, the membrane separation unit 2 in the membrane separation tank 1 can be moved to a membrane drawing water tank 5 filled with water while being buried in water.
Therefore, the gas such as methane gas discharged into the air in the membrane separation tank 1 is not brought into the water tank 5 for membrane extraction, and the membrane separation unit 2 is moved into the water tank 5 for membrane extraction from the membrane separation tank 1 in water. Can be moved. Since the membrane separation unit 2 moved to the membrane drawing water tank 5 is replaced in the membrane drawing water tank 5, the gas in the membrane separation tank 1 is not discharged out of the system of the methane fermentation water treatment apparatus. Replacement of the separation unit 2 can be achieved.

As described above, according to the present embodiment, the methane fermentation tank 3 and the membrane separation tank 1 are provided separately from each other, and the membrane separation unit 2 in the membrane separation tank 1 is It can be moved to the film extraction water tank 5 while being buried in the water in the film extraction water tank 5. Thereby, the exchange of the membrane separation unit 2 can be achieved without releasing the gas in the methane fermentation tank 3 and the gas in the membrane separation tank 1 out of the system of the methane fermentation water treatment apparatus.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS.

FIGS. 3 and 4 are views showing a third embodiment of the present invention. Here, FIG. 3 is a configuration diagram showing a methane fermentation tank, and FIG. 4 is a configuration diagram showing a methane fermentation water treatment device.

In the third embodiment shown in FIGS. 3 and 4, the methane fermentation tank 3 has a wastewater 6, and wastewater is supplied to the wastewater 6 via a wastewater supply pipe 14 having a wastewater pump 8. Is done. Further, at the bottom of the wastewater 6, there is provided an ejection hole 7 from which the wastewater flows out from the wastewater 6,
At the bottom of the wastewater 6, a second wastewater transport pipe connecting the jet hole 7 and the central side wall of the methane fermenter 3 is provided. Further, the wastewater 6 is provided with a pressure detector 9 for detecting the internal pressure of the wastewater 6, and the first controller 15a adjusts the rotation speed of the wastewater pump 8 based on a signal from the pressure detector 9. It has become.

In FIGS. 3 and 4, other configurations are substantially the same as those of the first embodiment shown in FIG. In FIGS. 3 and 4, the same parts as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted. Here, FIG. 3A is a diagram showing a methane fermentation tank, and FIG.
FIG. 4 is a plan view showing wastewater.

In FIGS. 3 and 4, wastewater is supplied to wastewater 6 by a wastewater pump 8 via a wastewater supply pipe 14. A part of the wastewater supplied to the wastewater 6 is discharged from a second outlet 7 of the wastewater 6 provided at the bottom of the methane fermenter 3.
The methane fermentation tank 3 is returned to the central part of the methane fermentation tank 3 via the wastewater return pipe 29b, and activates the methane fermentation in the methane fermentation tank 3.

During this time, the internal pressure of the wastewater 6 is detected by the pressure detector 9, whereby the pressure detector 9 outputs the first pressure.
A signal is sent to the control device 15a, and the rotation speed of the wastewater pump 8 is adjusted by the first control device 15a based on the signal. At this time, the rotation speed of the wastewater pump 8 is adjusted so that the internal pressure of the wastewater 6 is constant, so that a constant amount of wastewater can be ejected from the ejection holes 7 provided at the bottom of the wastewater 6.

The above-mentioned methane fermentation tank 3 can be used when the membrane separation tank 1 having the membrane separation unit 2 and the methane fermentation tank 3 are provided separately from each other as shown in FIG. It can also be used when the membrane separation unit 2 and the methane fermentation tank 3 are integrated.

As described above, according to the present embodiment, the wastewater is supplied to the wastewater 6 so that the internal pressure of the wastewater 6 becomes constant. Therefore, a fixed amount can be ejected from the ejection hole 7 provided at the bottom of the container 6. As a result, the wastewater spouted from the spouting holes 7 can be quantitatively returned to the methane fermentation tank 3 to stabilize the efficiency of methane fermentation.

Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to FIG.

FIG. 5 is a diagram showing a fourth embodiment of the present invention. Here, FIG. 5 is a configuration diagram showing a methane fermentation water treatment device.

In the fourth embodiment shown in FIG. 5, the upper part of the methane fermenter 3 is tapered upward,
A gas-solid-liquid separator 23 having an open top is provided. Further, a skimmer 25 for collecting scum is provided near the water surface in the methane fermentation tank 3 and at a position corresponding to the upper opening of the gas-solid liquid separating device 23. A plate 28 is provided. Further, the baffle plate 28 is provided near the water surface in the methane fermentation tank 3 and along the outer peripheral side of the movement region of the skimmer 25 so as not to hinder the movement of the skimmer 25. A motor 26 for driving the skimmer 25 is provided outside the methane fermentation tank 3 and the skimmer 2
5 and a scum pocket 27 from which scum scraped off by the skimmer 25 is scraped off.
Are provided below a part of the movable area of the skimmer 25. Other configurations are substantially the same as those of the first embodiment shown in FIG. 5, the same parts as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted.

In FIG. 5, the wastewater in the methane fermentation tank 3 is located at the lower part of the methane fermentation tank 3 where the anaerobic microorganisms 21 such as methane bacteria are present in a large amount. And a supernatant layer 22.

Scum is formed when bubbles of biogas generated by methane fermentation of wastewater in the anaerobic microorganism layer 21 do not burst. This scum floats above the liquid surface of the supernatant liquid layer 22. The scum floats along the gas-solid separation device 23 provided above the methane fermentation tank 3 and is accumulated in an open area above the gas-solid separation device 23 located below the movable region of the skimmer 25. . In this way, the scum is accumulated in the open region above the gas-solid liquid separation device 23, so that the scum can be scraped off efficiently by the skimmer 25. Further, a baffle plate 28 is provided near the water surface in the methane fermentation tank 3 and along the outer peripheral side of the movable area of the skimmer 25 so as not to hinder the movement of the skimmer 25.
The scum can be more efficiently scraped off by the skimmer 25. The scum scraped off by the skimmer 25 in this manner is the scum pocket 2
It is scraped by 7.

As described above, according to the present embodiment, the scum generated from the wastewater is accumulated in the open area above the gas-solid separation device 23, and the scum on the liquid surface moves the skimmer 25. The diffusion to the liquid surface outside the possible area can be prevented by the baffle plate 28. Thus, the scum can be efficiently scraped off by the skimmer 25, and the scum in the wastewater can be efficiently removed. By removing the scum in this manner, it is possible to prevent the flow of the wastewater in the methane fermentation tank 3 from being inhibited by the scum.

Fifth Embodiment Next, a fifth embodiment of the present invention will be described with reference to FIG.

FIG. 6 is a diagram showing a fifth embodiment of the present invention. Here, FIG. 6 is a configuration diagram showing a methane fermentation water treatment device.

In the fifth embodiment shown in FIG. 6, a scum discharge valve 10 is provided in the wastewater connection pipe 4 and the methane fermentation tank 3 is provided.
Among them, a discharge pipe 12 from which the wastewater and scum in the methane fermentation tank 3 can flow out is provided above the wastewater connection pipe 4. Other configurations are substantially the same as those of the first embodiment shown in FIG. 5, the same parts as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted.
The wastewater supply pipe 14 having the wastewater pump 8 is
Attached to.

In FIG. 6, scum is formed because the bubbles of biogas generated by methane fermentation of wastewater do not burst. This scum floats above the liquid level of the wastewater and is deposited on the liquid level. If the scum is left for a long period of time such as six months or more, the wastewater supply pipe 14 and the wastewater connection pipe 4 may be closed.

Therefore, in this embodiment, the scum discharge valve 10 is closed, and the level of the wastewater in the methane fermentation tank 3 is raised above the wastewater connection pipe 4. In this case, the methane fermentation tank 3 is disposed above the wastewater connection pipe 4 in the methane fermentation tank 3.
Since the discharge pipe 12 through which the waste water and scum in the inside can flow out is provided, the scum and the waste water flow out from the discharge pipe 12 when the liquid level reaches the height of the discharge pipe 12. In this way, the scum is removed from the methane fermentation tank 3.

As described above, according to the present embodiment, the scum discharge valve 10 is closed and the methane fermentation tank 3 is closed.
By raising the liquid level of the wastewater in the methane fermentation tank 3 to the height of the discharge pipe 12 provided above the wastewater connection pipe 4, the wastewater and scum are discharged from the discharge pipe 12, and the scum is discharged from the methane fermentation tank 3. 3 can be removed from within. By removing the scum in this manner, it is possible to prevent the flow of the wastewater in the methane fermentation tank 3 from being inhibited by the scum.

Sixth Embodiment Next, a sixth embodiment of the present invention will be described with reference to FIG.

FIG. 7 is a view showing a sixth embodiment of the present invention. Here, FIG. 7 is a configuration diagram showing a methane fermentation water treatment device.

The sixth embodiment shown in FIG. 7 is characterized in that an ultrasonic scum detection device 11 for detecting scum accumulated in the methane fermentation tank 3 is provided above the methane fermentation tank 3. Only the difference is that the other parts are substantially the same as the fifth embodiment shown in FIG. 7, the same parts as those in the fifth embodiment shown in FIG. 6 are denoted by the same reference numerals, and detailed description is omitted. The scum detection device 11 is connected to a second control device 15b that controls the scum discharge valve 10.
A wastewater supply pipe 14 to which the wastewater pump 8 is attached is connected to the methane fermentation tank 3.

In FIG. 7, the scum is formed because the bubbles of the biogas generated by the methane fermentation of the wastewater do not burst. This scum floats above the liquid level of the wastewater and is deposited on the liquid level. If this scum is left for a long period of time such as six months or more, for example, the wastewater supply pipe 14 and the wastewater connection pipe 4 may be closed. In this case, scum accumulated in the methane fermentation tank 3 is detected by the scum detection device 11 using ultrasonic waves, and a detection signal is sent to the second control device 15b. When the detected value of the deposited scum becomes equal to or more than a certain value, the scum discharge valve 10 is closed by the second control device 15b, and the liquid level of the wastewater in the methane fermentation tank 3 is raised above the wastewater connection pipe 4. To raise. in this case,
A discharge pipe 12 is provided above the wastewater connection pipe 4 in the methane fermentation tank 3 so that the wastewater and scum in the methane fermentation tank 3 can flow out.
Scum and wastewater are drained out of the drain 12
More outflow. In this way, the scum is methane fermentation tank 3
Removed from within.

As described above, according to the present embodiment, the amount of scum deposited in the methane fermentation tank 3 is detected by the scum detection device 11 using ultrasonic waves, and the detected value of the deposited scum is determined. When it has reached a certain value or more, it is closed via the second control device 15b. Thereby, the liquid level of the wastewater in the methane fermentation tank 3 is raised to the height of the discharge pipe 12 provided above the wastewater connection pipe 4 in the methane fermentation tank 3, and the wastewater and scum are caused to flow out of the discharge pipe 12. The scum can be removed from the methane fermenter 3.

[0052]

As described above, according to the present invention,
A methane fermentation tank for methane fermentation of wastewater and a membrane separation tank with a membrane separation unit for membrane separation of methane-fermented wastewater are provided separately from each other, and wastewater is connected to the membrane separation tank from the methane fermentation tank. Since the gas is supplied through the pipe, it is possible to prevent the gas in the methane fermentation tank from flowing out of the methane fermentation water treatment system, and to replace the membrane separation unit.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a methane fermentation water treatment apparatus according to the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the methane fermentation water treatment apparatus according to the present invention.

FIG. 3 is a configuration diagram showing a methane fermentation tank according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram showing a third embodiment of the methane fermentation water treatment apparatus according to the present invention.

FIG. 5 is a configuration diagram showing a methane fermentation water treatment apparatus according to a fourth embodiment of the present invention.

FIG. 6 is a configuration diagram showing a fifth embodiment of the methane fermentation water treatment apparatus according to the present invention.

FIG. 7 is a configuration diagram showing a methane fermentation water treatment apparatus according to a sixth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Membrane separation tank 2 Membrane separation unit 3 Methane fermentation tank 4 Wastewater connection pipe 5 Membrane drawing water tank 6 For wastewater 7 Vent hole 8 Wastewater pump 9 Pressure detector 10 Scum discharge valve 11 Scum detector 12 Discharge pipe 13 Gas valve 14 Wastewater Supply pipe 15a First control device 15b Second control device 21 Anaerobic microorganism layer 22 Supernatant liquid layer 23 Gas-solid liquid separation device 24 Gas holder 25 Skimmer 26 Motor 27 Scum pocket 28 Baffle plate 29a First wastewater return pipe 29b Second Wastewater return pipe 30 Permeate transport pipe 31a First gas transport pipe 31b Second gas transport pipe

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuo Shibasaki 2-4, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside Keihin Works, Toshiba Corporation (72) Inventor Nobuyuki Ashikaga Suehiro, Tsurumi-ku, Yokohama-shi, Kanagawa 2-4 Cho-cho, Toshiba Keihin Works Co., Ltd. 2-4, Suehiro-cho, Tsurumi-ku, Tokyo Toshiba Keihin Works Co., Ltd. 2-4 Suehirocho, Tsurumi-ku, Yokohama Inside Keihin Works, Toshiba Corporation (72) Inventor Takeshi Matsushiro Suehiro, Tsurumi-ku, Yokohama, Kanagawa 2-chome address 4 Toshiba Corporation Keihin workplace F-term (reference) 4D006 HA93 KB24 PA02 PB08 PC64 4D040 AA24 AA58 AA61 4D051 AA04 AB01 CA05 4D059 AA01 AA02 AA07 BA17 BA48 BE42 BK14 EA08 EB02

Claims (7)

[Claims] 1. A methane fermentation tank to which wastewater is supplied, a membrane separation tank which receives wastewater supplied from the methane fermentation tank and has a membrane separation unit immersed in the wastewater therein, a methane fermentation tank, and a membrane A methane fermentation water treatment apparatus, comprising: a wastewater connection pipe interposed between the separation tank and the separation tank. 2. The methane fermentation water treatment apparatus according to claim 1, wherein the end of the wastewater connection pipe on the side of the membrane separation tank is disposed below the surface of the wastewater in the membrane separation tank. 3. A membrane drawing water tank connected to the membrane separation tank, wherein the membrane separation unit in the membrane separation tank can be moved into the membrane drawing water tank. The methane fermentation water treatment apparatus according to claim 1. 4. The methane fermentation tank has a wastewater to which wastewater is supplied through a wastewater supply pipe having a wastewater pump. The wastewater is supplied to the methane fermentation tank with an orifice capable of discharging wastewater and an internal pressure. And a pressure detector for detecting an internal pressure for wastewater, wherein a rotation speed of the wastewater pump is adjusted based on a signal from the pressure detector. The methane fermentation water treatment apparatus according to the above. 5. A gas-solid separation device is provided at the upper part of the methane fermentation tank, which is tapered upward and is open at the upper part. 5. The methane fermentation water treatment apparatus according to claim 1, wherein a skimmer for collecting scum is provided at a position corresponding to an upper opening of the apparatus. 6. The methane fermentation water treatment apparatus according to claim 5, wherein a baffle plate for regulating a scum area is provided around the skimmer. 7. A wastewater connection pipe is provided with a scum discharge valve, and a discharge pipe capable of discharging wastewater and scum in the methane fermentation tank is provided above the wastewater connection pipe in the methane fermentation tank. The methane fermentation water treatment apparatus according to claim 1.