JP2511336B2 - Method and equipment for hydrogen production from organic wastewater and sludge - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing hydrogen from organic sewage or sludge, and more particularly to the production of hydrogen from organic sewage or sludge containing various pollutants due to the synergistic action of hydrogen-producing bacteria and photosynthetic bacteria. Hydrogen production method and device.

[0002]

2. Description of the Related Art Conventionally, organic sewage and sludge are usually subjected to anaerobic treatment (anaerobic digestion) such as high-temperature methane fermentation method, medium-temperature methane fermentation method and / or UASB method (upflow sludge blanket type methane fermentation method). Method, etc., to pollute polluted organic matter, and finally methane (CH ₄ ) which is an energy substance.
A method has been applied in which methane-fermented digested liquid is converted to carbon dioxide and methane-fermented digested liquid is usually anaerobicly treated to oxidatively stabilize the remaining organic matter and released. These treatment technologies can be evaluated as energy-saving treatment technologies if limited to the methane fermentation method. However, in the generated gas, carbon dioxide (CO ₂ ) which is a substrate of hydrogen-utilizing methane bacteria is included. Since the absolute amount of hydrogen is insufficient, about 40% of carbon dioxide, which has no value, remains as an energy source.

In addition, methane (C
When H ₄ ) also burns, carbon dioxide (CO
₂ ) occurs. CH ₄ + 2O ₂ → CO ₂ + 2H ₂ O As is well known, global environmental pollution has been taken up as a serious global problem for several years, and there is a strong demand for a solution and improvement from a global perspective. Among these, the global warming problem is a particularly familiar and serious problem.
From such a viewpoint, the methane fermentation method as a conventional technique intensively generates a large amount of carbon dioxide gas which directly affects global warming. Therefore, there is an urgent need to research and develop new organic sewage and sludge treatment technologies that can contribute to the improvement of the global environment.

[0004]

As described in detail above,
The methane fermentation method as a conventional technique is an energy-saving type and at the same time generates methane (CH ₄ ) which is an energy substance, but by burning this, CO ₂ which promotes global warming is generated, and methane is also generated. About 4 in fermentation gas
0% CO ₂ is always present. The inventors of the present invention have conducted extensive studies to improve this fatal defect of the conventional technique, provide an innovative method for treating organic sewage and sludge by a completely new expression, and provide a new multifunctional biological treatment. The purpose is to provide a process.

[0005]

In order to achieve the above object, in the present invention, when treating organic sewage or sludge in a methane fermentation tank, a specific methane fermentation blocking agent is added in advance and the fermentation treatment is carried out under reduced pressure. The present invention provides a method for producing hydrogen from organic wastewater or sludge, which is characterized in that hydrogen is produced by the method. Further, the present invention provides the red-colored bacteria under the condition of supplying CO ₂ after the reduced pressure fermentation treatment. The method for producing hydrogen from organic sewage and sludge is characterized by culturing photosynthetic bacteria under light and anaerobic conditions.

In order to achieve the above-mentioned other objects, the present invention has a reduced pressure fermenter and a reduced pressure diffusion column communicating with the liquid in the fermenter, and the reduced pressure fermenter contains waste water and sludge. It has an introduction pipe and a drain pipe, the sewage and sludge introduction pipe is connected to an inlet for a methane fermentation blocking agent, and a circulation path for circulating the fermentation tank content liquid is provided at the top of the reduced pressure diffusion tower, and The reduced-pressure stripping tower is a hydrogen production device from organic wastewater or sludge, characterized in that a gas transfer pipe through a vacuum pump is provided, and the hydrogen production device of the present invention is , Further has a light and anaerobic photosynthetic bacterial culture tank, the drainage pipe of the reduced pressure fermentation tank is connected to the photosynthetic bacterial culture tank,
Further, a hydrogen production apparatus from organic wastewater or sludge characterized in that a gas transfer pipe from the reduced pressure diffusion tower is connected to the bottom of the culture tank, and an exhaust gas pipe of the culture tank is connected to the gas transfer pipe. It is what

That is, according to the present invention, acetic acid-assimilating methane bacteria, hydrogen-assimilating methane bacteria and / or homoacetic acid methane bacteria which are wildly inhabiting in the methane fermentation tank contents liquid are converted from their respective substrates with methane. A co-enzyme M (CO-enzyme-M), which is necessary for the production of methane, is produced, and a methane fermentation blocking agent that inhibits this production and / or an antibiotic that directly acts on methane bacteria are treated. Add to organic sewage or sludge to be, fermented under reduced pressure in a fermenter equipped with a decompression diffusion tower, to disperse hydrogen dissolved in the liquid and methane fermentation blocking agent after the reaction into the gas phase, high speed ,
It is a method of treating organic wastewater and sludge that enables highly efficient hydrogen fermentation.

Further, the present invention uses lower fatty acids contained in the reduced pressure fermentation broth as photosynthetic bacteria, that is, the red-colored bacteria Rhodopseudomonas, Rhodospirillum and / or Chromium.
It is also a treatment method that includes a step of converting to hydrogen under a light / anaerobic condition by a mixture such as atium). The present invention is also a treatment method designed to recycle the bacterial cells grown in the photosynthetic bacterial culture tank into feed and / or valuable materials.

Next, the present invention will be described in detail. The present invention
A specific methane fermentation blocking agent is added to organic sewage or sludge containing various organic pollutants to produce hydrogen under reduced pressure fermentation conditions, and in the next photosynthetic bacteria (red bacterium) culture tank, a red color is produced. It transforms lower fatty acids (mainly acetic acid) into hydrogen by the function of bacteria.
Thus, various hydrogen bacteria and photosynthetic bacteria (purple bacteria)
By combining the functions of the above, it is possible to treat organic sewage and sludge, and at the same time produce hydrogen, which is a clean energy, as well as a novel organic material that enables the production of substances by effectively utilizing the growing cells. The present invention relates to a method for producing hydrogen (fermentation) from sewage and sludge.

Next, the excellent function and effect of the present invention will be described with reference to FIG. First, referring to FIG. 1, for example, the organic wastewater is previously treated with a methane fermentation blocking agent such as carbon tetrachloride (CCl ₄ ), chloroform (CHC).
l ₃ ), methylene chloride (eg CH ₂ Cl ₂ ),
2-Bromoethanesulfonic acid (BrCH ₂ · CH ₂ S
O ₃ H) or the like in an amount of 1 μmol / l to 500 μmol / l and / or an antibiotic such as methyl viologen (Methylviologen) or benzyl viologen (Benzylviologen).
After being added in a concentration range of μmol / l to 50 μmol / l, it is introduced into the reduced pressure fermentation tank 2 through the sewage or sludge introduction pipe 1. The vacuum fermentation tank 2 is provided with a tower-shaped vacuum diffusion tower 4, and the lower end of the diffusion tower communicates with the liquid below the liquid content of the vacuum fermentation tank. Further, the inside of the diffusion tower is maintained at a reduced pressure of -400 to 5,000 mmAq by the vacuum pump 5.

With respect to the stripping tower under the reduced pressure condition, the content liquid of the reduced pressure fermentation tank 2 is circulated a plurality of times by the circulation pump 3,
Hydrogen and / or volatile methane fermentation blocking agent dissolved in the content liquid is diffused at the same time as the content liquid in the tank is appropriately stirred. By adding the operation of this reduced pressure diffusion, hydrogen fermentation in the reduced pressure fermenter is performed at high speed, with high efficiency without delay, and the methane fermentation blocking agent is also recovered.
The recovered same agent is sucked into the wastewater to be treated by the gas transfer pipe 7. (Since the released gas does not contain oxygen, anaerobic fermentation is not impeded at all.) In addition, in order to minimize the amount of hydrogen dissolved in the liquid contained in the vacuum fermentation tank, a bracket is attached to a movable basket that can be freely taken in and out of the tank. It is also possible to adopt a method in which the hydrogen storage alloy 19 in the form of a ring is filled and activated for reuse.

The organic reaction material solubilized in the reduced pressure fermentation tank 2 is represented by hexose (glucose), and the biological reaction formula of hydrogen fermentation in the same tank is shown below. Hydrogen production from organic matter (hexose) C ₆ H ₁₂ O ₆ + 2H ₂ O → 2CH ₃ COOH + 2CO ₂ + 4H ₂ (1) Next, the so-called fermentation digestion liquid after hydrogen fermentation in the reduced pressure fermentation tank 2 is represented by the formula (1) Not only does it contain acetic acid as shown in, but it also contains a considerable amount of persistent SS components that cannot be liquefied by vacuum fermentation. Therefore, a solid-liquid separation device such as an ordinary gravity type sedimentation tank or a centrifuge is provided in the middle of the outflow pipe 8 for transferring the digested liquid from the reduced pressure fermentation tank to the photosynthetic bacterial culture tank 10, and the SS content is reduced as much as possible. After the removal, the digestive juice is introduced into the photosynthetic bacterium culture tank 10. The photosynthetic bacterium culture tank 10 is maintained in an anaerobic condition, and the solar energy collected by the solar light collector 11 is transmitted to the optical fiber 12 set in the tank 10 in the tank 10. The same tank is maintained under light and anaerobic culture conditions.

CO ₂ required by photosynthetic bacteria is
The evolved gas diffused (withdrawn) from the reduced pressure diffusion tower 4 of the reduced pressure fermentation tank 2 is supplied from the bottom of the photosynthetic bacterium culture tank 10 by the gas transfer pipe 6 and biologically fixed under the above conditions. However, the supplied CO ₂ is the gas circulation pipe 9-6.
It is circulated through and is effectively used by purple bacteria. In the photosynthetic bacterium culture tank 10, so-called red-colored bacteria are cultivated in a concentrated manner corresponding to the amount of acetic acid, and these are usually Rhodopseudomonas, Rhodospirillum and / or Chromatium. ), The acetic acid in the digestive juice is converted to hydrogen by these red bacteria according to the following biological reaction formula. CH ₃ COOH + 2H ₂ O → 2CO ₂ + 4H ₂ (2) The gas generated from the tank 10 is taken out of the tank 10 by the gas drawing pipe 13 and is used as a clean energy for various purposes.

The water flowing out from the photosynthetic bacterium culture tank 10 contains a little undigested acetic acid and may cause a problem in discharging it to the outside as it is. Therefore, there is no particular limitation via the outflow pipe 14. Introduced into a normal bio-oxidizer 15,
While supplying air (oxygen) by the blower 16, residual organic matter, that is, a trace amount of acetic acid is biologically oxidatively decomposed and is discharged as totally harmless treated water to an external river, lake or ocean through a discharge pipe 18. It Further, as described above, since the surplus bacterial cells of the red bacterium grown in the photosynthetic culture tank 10 include various trace components and physiologically active substances effective as a feed substance, the surplus bacterial cell discharge pipe 20 is used to remove them from the tank. It is taken out, used as feed and / or recycled as valuable resources.

[0015]

The treatment method of the present invention is a clean energy that replaces methane by allowing the hydrogen-producing anaerobic bacteria to grow as the dominant species by adding some technical improvements to the conventional methane fermentation method. The first feature is to generate a large amount of hydrogen, and the second is to convert acetic acid dissolved in the treated water in the reduced pressure fermenter into hydrogen.
The above-mentioned individual processing steps can achieve the function and purpose of hydrogen production independently. The total amount of hydrogen generated from this new process is large, and not only can CO ₂ which is a causative agent of global warming be recycled, but also the absolute amount of generated CO ₂ is small.

Therefore, the present invention is an epoch-making method for producing hydrogen from organic sewage and sludge, which contributes significantly to global environmental protection and improvement as a total process. Further, in the treatment technology of the present invention, since the surplus bacterial cells of purple bacteria are utilized as resources, so-called not only the troublesome sludge treatment of the conventional treatment technology is alleviated, but it was effectively used for various purposes. Useful substances are incorporated in harmony with the natural ecosystem, and are accepted without difficulty in the material cycle cycle in nature. Further, the acetic acid produced in the reduced pressure fermenter does not need to be converted into hydrogen by the red bacterium, and it can be separated and purified as acetic acid and used as a raw material for organic synthesis.

[0017]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 Sewage sludge generated from an urban sewage treatment plant was selected as the treatment symmetry for hydrogen fermentation. The input sludge used in the experiment was a mixture of the first settling tank sludge, which was gravity settled and concentrated at a certain sewage treatment plant, and the mechanically concentrated excess activated sludge, at a solids weight ratio of 2: 1, and the total solids concentration of the mixed liquid. Was adjusted to about 30 g / l by adding tap water and refrigerated at 3 to 5 ° C so as not to deteriorate during the experimental period.

Table 1 shows the composition of the input sludge.

[Table 1]

Regarding the volume of the hydrogen fermenter, two cylindrical fermenters having an actual water-filled volume (effective volume) of 5 liters were manufactured, and these were set in a constant temperature water bath of 35 ° C. for medium temperature fermentation. Of the two fermenters, one did not add a methane fermentation blocking agent as a control, and the other one selected methane dichloride (CH ₂ Cl ₂ ) as a methane fermentation blocking agent, and 10 μmol / l was added. In addition, the two hydrogen fermentation tanks are all
The pressure was reduced to 4,000 mmAq, and vacuum fermentation was performed. The amount of sludge input to the reduced pressure fermenter was 0.35 liters / day, and therefore the number of fermentation days in both fermenters was approximately 15 days.

Next, in the series to which the methane fermentation blocking agent was added, the fermented digested liquid was subjected to centrifugal force of 3,000 G to remove the SS content from the fermented digested liquid.
Introduced into a 5-liter photosynthetic bacterial culture tank, Rhodopseudomonas, Rhodospirillum (Rhod
ospirillum) and / or Chromatium
Hydrogen was produced by giving a residence time of about 7 days as a continuous system to the culture medium in which hydrogen was mixed. The treated water temperature was 35 ° C., and the bacterial cell concentration varied within the range of 5,000 to 6,000 mg / l. As the CO ₂ supplied to the photosynthetic bacteria, the gas generated from the reduced pressure fermenter, that is, H ₂ + CO ₂ gas was used, and a part of it was circulated in order to enhance the utilization efficiency of carbon dioxide gas. The light energy to be supplied to the photosynthetic bacterial culture tank is determined by the bacterial cell concentration and the bacterial cell amount, but it may be set in the range of approximately 8 to 10 kW / m ³ · hr, judging from the experimental results.

The supply rate of the light energy to be transmitted to the surface of the light energy is 25 to 40 W / m ² · hr, which is sufficient. Therefore, in this experiment also, it was set to fall within this range. The verification experiment by the above experimental apparatus continued for 3 months after the operation was in a steady state, and Table 2 shows the treatment results (average value) for 1 month in the intermediate process.

[Table 2]

As is clear from the experimental results shown in Table 2,
Even if the fermentation under reduced pressure is performed, unless the methane fermentation blocking agent is added, the methane fermentation proceeds as usual, and the concentration of acetic acid remaining in the digestion liquid under reduced pressure (volatile fatty acid concentration)
Is an extremely low concentration, and therefore, even if hydrogen is produced by photosynthetic bacteria, the amount of hydrogen produced is substantially zero. On the other hand, in the vacuum fermentation with the addition of a methane fermentation blocking agent, obviously hydrogen fermentation is carried out, and further, a large amount of acetic acid dissolved in the vacuum digestion liquid can be converted into hydrogen as clean energy by photosynthetic bacteria. it can.

[0023]

According to the present invention, as described in detail, the present invention is based on an idea from a completely different viewpoint from the prior art, and has the following operational effects. (1) By adding a very small amount of a methane fermentation blocking agent to organic sewage or sludge, and performing vacuum fermentation, it is possible to convert pollutants into hydrogen, which is clean energy, and it significantly contributes to the prevention of global warming. be able to. (2) Hydrogen [H ₂ ] and acetic acid [C] produced by hydrogen-utilizing methane bacteria, acetic acid-utilizing methane bacteria, and homoacetic acid methane bacteria
The methane production reaction from [H ₃ COOH] is an energy consumption reaction, and it can be evaluated that artificially controlling it in the hydrogen fermentation stage is an energy-saving environmental conservation technology.

(3) Furthermore, not only can lower carboxylic acids, mainly acetic acid, contained in the reduced-pressure fermentation digestion liquid be converted into hydrogen by red-colored bacteria under light and anaerobic conditions, but also in the gas generated from the reduced-pressure fermentation tank. It is also possible to immobilize the causative agent of global warming as a valuable resource by sending the contained CO ₂ to a red-colored bacterial culture tank, and therefore, the present invention is an energy-creating treatment technology. At the same time, it is a processing technology capable of producing substances. (4) The so-called surplus cells grown in the photosynthetic microorganism culture tank can be used as feed for livestock, poultry, etc. and / or can be converted into valuable materials, and can form a material circulation system in the area. It is arguable that in the future, biological treatment processes that combine the functions of anaerobic hydrogen-producing bacteria and photosynthetic bacteria will become the mainstream of next-generation treatment technology.

[Brief description of drawings]

FIG. 1 is a flow process diagram showing an example of a hydrogen production method of the present invention.

[Explanation of symbols]

1: Sewage or sludge introduction pipe, 1 ': Blocking agent introduction pipe,
2: reduced pressure fermentation tank, 3: circulation pump, 4: reduced pressure diffusion tower,
5: Vacuum pump, 6, 7: Gas transfer pipe, 8, 14: Outflow pipe, 9: Gas circulation pipe, 10: Photosynthetic bacterium culture tank, 11:
Sunlight concentrator, 12: optical fiber, 13: gas extraction tube, 15: biooxidizer, 16: blower, 21: solid-liquid separator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // (C12P 3/00 (C12P 3/00 C12R 1:01) C12R 1:01)

Claims (5)

(57) [Claims] 1. When treating organic wastewater or sludge in a methane fermentation tank, hydrogen is produced by adding a specific methane fermentation blocking agent in advance and subjecting it to reduced pressure fermentation to produce hydrogen. Method of hydrogen production from Japan. 2. The organic fermented water or sludge according to claim 1, wherein after the reduced pressure fermentation treatment, a photosynthetic bacterium culture treatment with bright red and anaerobic conditions by a red bacterium under CO ₂ supply condition is performed. Hydrogen production method. 3. A reduced pressure fermentation tank and a reduced pressure diffusion tower communicating with the liquid in the fermentation tank, wherein the reduced pressure fermentation tank has a waste water and sludge introduction pipe and a drain pipe, and the waste water and sludge introduction are provided. The pipe is connected to an inlet for a methane fermentation blocking agent, and a circulation path for circulating the fermenter content liquid at the top of the reduced pressure diffusion tower is provided.
Further, the decompression / emission tower is provided with a gas transfer pipe via a vacuum pump, which is a hydrogen production device from organic wastewater or sludge. 4. The hydrogen production device further comprises a light / anaerobic photosynthetic bacterial culture tank, a drainage pipe of the vacuum fermentation tank is connected to the photosynthetic bacterial culture tank, and a gas from the vacuum stripping tower is supplied. The hydrogen production device from organic wastewater or sludge according to claim 3, wherein a transfer pipe is connected to the bottom of the culture tank, and an exhaust gas pipe of the culture tank is connected to the gas transfer pipe. 5. The apparatus for producing hydrogen from organic wastewater or sludge according to claim 4, wherein a solid-liquid separator is provided in a drain pipe connecting the reduced-pressure fermentation tank and the photosynthetic bacteria culture tank.