JP2885737B2 - Methane fermentation equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a fermented wastewater containing organic substances, which is fermented with methane bacteria, and the digested and desorbed liquid is subjected to solid-liquid separation using a suction type separation membrane and the separated permeate is treated water. The present invention relates to a methane fermentation apparatus that takes out the organic matter-containing wastewater and processes the wastewater.

[0002]

2. Description of the Related Art As an example of a wastewater treatment apparatus combining a production reaction apparatus and a membrane separation apparatus, there is a methane fermentation apparatus for treating high-concentration organic wastewater. This methane fermentation apparatus is a kind of organic substance-containing wastewater treatment apparatus aimed at obtaining clear treated water while maintaining fermentation efficiency of methane bacteria by maintaining methane bacteria at a high concentration. This methane fermentation apparatus uses a UF (Ultra Filtr) digestion / desorption solution obtained by decomposing organic substance-containing wastewater with methane bacteria.
ation) membrane and MF (Micro Filtati)
on) A method has been devised in which permeation treatment is performed with a membrane or the like to make clean water.

[0003] As an example of this methane fermentation apparatus, for example, Japanese Patent Application Laid-Open No. 62-181772 discloses a biological reaction apparatus. In order to reduce the power cost and the size of the device, this device is equipped with a hollow fiber membrane, a capillary membrane, and a tubular membrane in a biological reactor integrated with a product reactor and a separator. The gas generated in the above is collected, blown from below the membrane, aerated the biological treatment liquid, and subjected to membrane separation treatment to take out permeated water and treat the biological treatment liquid.

Further, since this bioreactor has only one bioreactor, the efficiency of membrane separation per installation space can be increased and the cost of power can be reduced because only one pump for circulating the biological treatment liquid is required. It has the characteristic that it only needs to be done.

[0005]

In the above-described biological reaction apparatus in which the separation membrane treatment is performed in one tank, the size and power cost can be reduced. However, when applied as a methane fermentation apparatus, organic substances containing organic matter are directly contained in the separation tank. Water.
There is a disadvantage that it takes time for the organic matter-containing water to ferment and become an activated digestion-desorbed solution, resulting in a long overall treatment time. Also, when digestion / elimination liquid generated by methane fermentation is treated with a UF membrane or MF membrane module, so-called SS (suspended solid), which is a microparticle floating every time the digestion / elimination liquid in the tank circulates, increases. Eventually, the SS clogs the membrane and reduces the processing capacity of the device. For example, even if the membrane member is set upright so as to be along the flow direction of the digestion / desorption liquid, the floating SS adheres to the membrane member and causes clogging.

In order to replace a clogged membrane member,
In this apparatus, the biological reaction tank must be opened and then replaced. This replacement operation causes the air and residual chemicals in the transfer tube to come into contact with the atmosphere and lose the activity of methane bacteria. In the case of methane fermentation, methane bacteria live under absolutely anaerobic conditions, so that once the anaerobic condition is destroyed, there is a problem that the cell activity is immediately inactivated and it takes a lot of time to activate the cells again.

Accordingly, an object of the present invention is to provide a methane fermentation apparatus that efficiently treats organic matter-containing wastewater in a shorter time while always maintaining a high anaerobic state of methane even when a membrane member is replaced.

[0008]

SUMMARY OF THE INVENTION The present invention is characterized in that a high-concentration organic water to be supplied is digested and desorbed by fermentation with methane bacteria and a methane fermentation tank of a closed container for storing biogas generated by fermentation. Pump from this methane fermentation tank
A separation tank that introduces the digestion / desorption solution through a supply pipe, a high-pressure gas storage tank that introduces and accumulates the biogas through a second supply pipe, and an introduction from the high-pressure gas storage tank. A bubbler for aerating the digestion / desorption solution introduced from the bottom of the separation tank by the biogas, and the digestion / desorption solution is aerated and sucked by the pump to remove fine particles.
A suction type separation membrane such as a hollow fiber to be captured, and the suction type separation membrane
Measure the suction pressure of the pump to detect the degree of clogging
A pressure gauge, and a discharge pipe for taking out the treated water separated from the digested separation liquid by the suction type separation membrane by the pump,
A return pipe for returning an excess portion of the digestion and desorption solution supplied to the separation tank to the methane fermentation tank, and a third transmission for sending the biogas generated in the separation tank to the high-pressure gas storage tank. This is a methane fermentation apparatus including a supply pipe. Further, the first feed pipe, the second feed pipe, and the return
Opening / closing valves are provided in each piping route of the sending piping
It is not the desirable you are.

[0009]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a methane fermentation apparatus according to one embodiment of the present invention. As shown in FIG. 1, this methane fermentation apparatus is a closed container for storing a digestion-desorbed liquid in which high-concentration organic substance-containing water supplied from a raw water intake 6 is fermented by methane bacteria and biogas generated by fermentation. The methane fermentation tank 2, the separation tank 1 that is sucked from the methane fermentation tank 2 by the suction pump 11 and introduces the digestion / desorption liquid through the digestion / desorption liquid supply pipe 7, and gaseous biogas from the methane fermentation tank 2 A high-pressure gas storage tank 5 for introducing and accumulating via a supply pipe 12, a bubbler 4 for aerating a digestion / desorption solution introduced from the bottom of the separation tank 1 with biogas introduced from the high-pressure gas storage tank 5, Syneresis is aerated and suction pump 1
1, a suction-type membrane module unit 3 such as a hollow fiber for sucking and promoting fine particles, and a treated water discharge pipe 10 for taking out treated water separated from digested and separated liquid by a hollow fiber membrane 3a by a suction pump 11; A concentrated liquid feed pipe 8 for returning the surplus portion of the digestion / desorption liquid supplied to the tank 1 to the methane fermentation tank 2, and a gas supply for feeding biogas generated in the separation tank 1 to the high-pressure gas storage tank 5. And a supply pipe 12a.

Here, the operation of the methane fermentation apparatus will be described. First, the organic substance-containing water introduced into the methane fermentation tank 2 is converted into a digested / desorbed liquid having a low BOD and biogas by methane bacteria. Then, the digestion / elimination liquid containing methane bacteria enters the separation tank 1, and the digestion / elimination liquid is captured by the hollow fiber membrane 3 a by the hollow fiber membrane 3 a with the aeration of biogas. Then, the treated water passing through the hollow fiber membrane 3a of the suction type membrane module unit 3 is discharged from the treated water discharge pipe 10 through the water collecting pipe 9 to the outside of the apparatus.

On the other hand, the concentrate, which is a digestion and elimination liquid containing the concentrated cells circulating in the tank, is returned to the methane fermentation tank 2 in order to keep the liquid level constantly constant. Therefore, the inside of the methane fermentation tank 2 which is a seamless closed vessel always keeps a high anaerobic state. In the methane fermenter 2, the organic matter-containing water to be introduced is fermented and stored with high efficiency because the cells are concentrated at a high density.

The biogas generated in the methane fermentation tank 2 and the separation tank 1 is mainly composed of methane and carbon dioxide, and does not contain oxygen. Then, it is always stored in the high-pressure gas storage tank 5 and supplied to the bubbler 4 as needed. Then, the aeration by the biogas acts to clean the hollow fiber membrane and removes SS adhering to the membrane, thereby delaying clogging of the membrane. As a result, long-time operation becomes possible, and the high fermentation rate of the methane fermentation tank can always be maintained at a high level.

As a trial, pork manure wastewater was introduced into the apparatus equipped with a hollow fiber membrane and treated, and the digestive fluid flowing from the methane fermentation tank to the membrane separation tank was intermittently 10 L / m 2 of membrane area per square meter. Purified treated water was obtained by membrane filtration over hr. When the concentrated liquid containing methane bacteria was recirculated to the methane fermentation tank, 90% or more of the organic acids in the undiluted solution serving as an indicator of methane fermentation were removed, and about 36 kg / kg of organic matter was removed.
Since 0 L of methane gas was generated, a highly efficient fermentation reaction was confirmed.

Although this methane fermentation apparatus prevents the adhesion of SS by bubbling biogas to the hollow fiber membrane 3a, the hollow fiber membrane 3
“a” causes clogging and reduces the processing capacity. This hollow fiber membrane 3
In the present invention, a pressure gauge 13 is provided in the treated water discharge pipe 10 in order to determine the allowable value of clogging a. This pressure gauge 13
When the pressure drops below a certain prescribed pressure, the hollow fiber membrane 3a is replaced.

The replacement of the intermediate filament membrane 3a must be performed so that the activity of the cells stored in the methane fermenter 2 is not lost. Therefore, in the present invention, the digestion and desorbed liquid in the methane fermentation tank 2 is not exposed to the atmosphere, and the separation tank 1 is not exposed to the atmosphere.
Opening / closing valves 14a and 14 that close pipes in advance in order to pull up the pulling type membrane module unit 3 with a lid from
b, 14c and 14d are provided.

That is, in order to replace the stop membrane 3a, the supply of raw water is stopped, the open / close valve 14d is closed, the open / close valves 14a, 14b, and 14c are subsequently closed in that order, and the digestion / elimination liquid remaining in the separation tank 2 is removed. Is returned to the methane fermentation tank 2 by a pipe (not shown) and a pump, and then the gas
2. Remove the respective joints of the digestion / desorbed liquid supply pipe 7 and the concentrated liquid supply pipe, and the joint between the suction pump 11 and the treated water discharge pipe 10, and use a lifting device (not shown) to perform a suction-type membrane module unit. 3 is pulled up together with the lid of the separation tank 1, and the hollow fiber membrane 3a is replaced with a new one. Next, after the replacement is completed and the pipes are connected and the lid is closed, nitrogen gas is introduced from the drain port of the separation tank (not shown) to completely dry the inside of the tank. This is to prevent the cell activity of the digestion / elimination liquid introduced from the methane fermentation tank 2 from being lost.

[0018] Even after the replacement of the intermediate filament membrane, there is an advantage that the digestion / elimination liquid containing more cells than the methane fermentation tank 2 can be immediately introduced and treated immediately.

[0019]

As described above, according to the present invention, a liquid introduced from a methane fermentation tank is separated from a methane fermentation tank separately from a methane fermentation tank having a closed structure in which water containing an organic substance is fermented with methane bacteria and a digestion / desorption liquid is stored. A suction membrane for aerating and permeating the digested and separated liquid decomposed in step (a), and separating the microparticles and treated water with the suction membrane and discharging the treated water and an excess pipe containing excess methane bacteria. By providing a separation tank equipped with a feed pipe for returning the concentrated liquid to the methane fermentation tank, and by using biogas generated from the methane fermentation tank and separation tank by methane bacteria for aeration of solid and liquid, the suction membrane can be effectively used. In addition, the fermentation efficiency of the methane fermentation tank is always kept constant, and the apparatus can be operated for a long time without reducing the processing efficiency.

Further, by providing the methane fermentation tank with a closed structure and providing a means for sealing the openings of the gas pipe and the liquid supply pipe around the tank, even if the suction membrane is exchanged, it can be stored in the methane fermentation tank. Since the digestion / elimination liquid can be performed without exposing it to the atmosphere, the anaerobic state of the digestion / elimination liquid in the methane fermentation tank can always be maintained at a high level.

[Brief description of the drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Separation tank 2 Methane fermentation tank 3 Suction type membrane module unit 3a Hollow fiber membrane separation 4 Bubbler 5 High-pressure gas storage tank 6 Raw water intake port 7 Digestion / desorption liquid supply pipe 8 Concentrate supply pipe 9 Water collection pipe 10 Treatment water discharge pipe 11 Suction pump 12, 12a Gas supply pipe 13 Pressure gauge 14a, 14b, 14c, 14d Open / close valve

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C12M 1/00

Claims (2)

(57) [Claims] A high-concentration organic water to be supplied is a methane fermentation tank of a closed container for storing a digestion-desorbed liquid obtained by fermentation with methane bacteria and a biogas generated by fermentation. A separation tank for introducing the digestion / desorption solution via a first supply pipe, a high-pressure gas storage tank for introducing and accumulating the biogas via a second supply pipe, and an introduction from the high-pressure gas storage tank A bubbler for aerating the digestion / desorbed liquid introduced from the bottom of the separation tank by the biogas to be drawn, and a vacuum type separation of a hollow fiber or the like which aerates the digested / desorbed liquid and aspirates with the pump to capture fine particles. Membrane, for detecting the degree of clogging of the suction type separation membrane
A pressure gauge for measuring a suction pressure of a pump, a discharge pipe for taking out the treated water separated from the digested and separated liquid by the suction type separation membrane by the pump, and a surplus of the digested and separated liquid supplied to the separation tank. A methane fermentation apparatus, comprising: a return pipe for returning a part to the methane fermentation tank; and a third supply pipe for feeding the biogas generated in the separation tank to the high-pressure gas storage tank. 2. The first feed pipe and the second feed distribution.
Opening / closing valves are provided in each pipe route of the pipe and the return pipe.
Methane fermentation apparatus according to claim 1, characterized in that provided.