JP5424293B2 - Biological treatment apparatus and biological treatment method - Google Patents

Description

  The present invention relates to a biological treatment apparatus and a biological treatment method.

  In the treatment of waste, wastewater, sewage, sewage sludge, etc. in agriculture, livestock industry, fishery industry, etc., a method of biologically treating these with anaerobic microorganisms has been developed and put into practical use. Organic substances contained in these wastes, wastewaters, and the like are fermented by anaerobic microorganisms, and finally methane, carbon dioxide, and hydrogen gas are generated. For this reason, wastes and wastewater are treated, and at the same time, a gas released into the gas phase is recovered and a specific gas such as methane gas is separated from the gas.

  Methods for concentrating and separating methane gas by removing carbon dioxide from gas generated from waste and wastewater, etc., chemical absorption method, physical absorption method, PSA (Pressure Swing Adsorption) method, separation method using separation membrane, etc. Is mentioned. Of these, a separation method using a separation membrane is preferable because the system can be simply configured and the apparatus can be made relatively small.

As a method of separating methane gas using a separation membrane, the gas generated from the landfill site by the action of anaerobic microorganisms and recovered in the gas phase is recovered, and the methane gas is passed through the separation membrane which is easy to pass carbon dioxide. A method for separating the two is shown (Patent Document 1).
Also shown is an apparatus that recovers a mixed gas of methane gas and carbon dioxide gas generated by wastewater treatment by anaerobic microorganisms and released into the gas phase, and separates and uses the methane gas from the mixed gas using a separation membrane. (Patent Document 2).
JP 61-53994 A Japanese Patent Laid-Open No. 4-177013

In such a conventional biological treatment method and biological treatment apparatus, the gas generated from the waste and released into the gas phase during the biological treatment is recovered. However, since these gases are produced by anaerobic microorganisms, they are consumed before being released into the gas phase from waste or wastewater, or remain in waste, wastewater, or microbial aggregates (ie, biofilms). The gas that had been recovered could not be recovered. For this reason, the gas recovery amount of the whole system in the biological treatment method or the biological treatment apparatus cannot be increased, and the energy recovery amount cannot be increased.
Therefore, there is a demand for a method that can recover the gas that has been consumed or remained in waste or wastewater.

  Accordingly, an object of the present invention is to provide a biological treatment apparatus and a biological treatment method that can recover gas that has been consumed or remained in a treatment object such as waste or wastewater.

The biological treatment apparatus of the present invention includes a biological treatment tank that biologically treats an object to be treated to generate gas, and a non-water-permeable material that is disposed in the biological treatment tank so as to be in contact with the object to be treated and allows gas to pass therethrough . A gas separation means having a separation membrane, a decompression means for decompressing the inside of the gas separation means, and a gas storage means for collecting and storing the gas discharged from the decompression means. Device.

In the biological treatment apparatus of the present invention, it is preferable that the gas separation means includes a microorganism supporting mechanism on the surface of the separation membrane or in the vicinity thereof.
The separation membrane is preferably a non-permeable separation membrane.
The separation membrane is preferably a gas selective permeable separation membrane.

Further, the biological treatment method of the present invention is a biological treatment method in which an object to be treated is biologically treated to generate a gas, and the gas is recovered, wherein the gas separation means having a non-permeable separation membrane that allows gas to permeate is provided. In this method, the gas separation means is brought into contact with a processing object, the pressure inside the gas separation means is reduced, the gas is separated from the processing object, and the separated gas is recovered.
In the biological treatment method of the present invention, it is preferable to form a biological layer on the surface of the separation membrane.

  The biological treatment apparatus and biological treatment method of the present invention can recover gas that has been consumed or remained in a treatment object such as waste or wastewater.

[Biological treatment equipment]
The biological treatment apparatus of the present invention includes a biological treatment tank that biologically treats a treatment target object to generate gas, and a separation membrane that is disposed in the biological treatment tank so as to come into contact with the treatment target object and transmits gas. The apparatus includes: a gas separating unit having a pressure reducing unit that depressurizes the inside of the gas separating unit.

(First embodiment)
FIG. 1 is a configuration diagram showing an example of a biological treatment apparatus of the present invention. The biological treatment apparatus 10 includes a biological treatment tank 12, a gas separation means 14 disposed in the biological treatment tank 12, a decompression means 16 connected to the gas separation means 14, and a surface of the gas separation means 14 or in the vicinity of the surface. A microorganism holding mechanism 18 is provided, and a gas storage unit 22 that stores the gas discharged from the gas discharge port 20 and the decompression unit 16 in the upper part of the biological treatment tank 12.

  Examples of the biological treatment tank 12 include an anaerobic biological treatment tank in which an organic substance contained in a treatment target is fermented by anaerobic microorganisms under anaerobic conditions to generate gas. The shape of the biological treatment tank 12 is not particularly limited, and shapes corresponding to various uses can be used.

The gas separation means 14 has a separation membrane that allows gas to pass therethrough.
Examples of the gas separation means 14 include known separation membrane modules (hollow fiber membrane modules, flat membrane modules, etc.).
Examples of the separation membrane include hollow fiber membranes and flat membranes, and hollow fiber membranes are preferred from the viewpoint of a large surface area and a high filling rate.

  The separation membrane is preferably a water-impermeable separation membrane because it is easy to separate and recover a gas that does not contain moisture even when biologically treating an object to be treated with a high moisture content. A hollow fiber membrane is more preferable. Examples of the non-permeable hollow fiber membrane include a separation membrane made of a hydrophobic material and a three-layer structure membrane in which a gas-permeable non-porous separation layer is sandwiched between porous support layers. The three-layer structure membrane is suitable as a separation membrane because the porous support layer also serves as the microorganism-supporting mechanism 18 described later.

  The separation membrane is preferably a gas selective permeable separation membrane and more preferably a gas selective permeable hollow fiber membrane from the viewpoint that it is easy to separate and recover useful gases such as hydrogen and methane at a high concentration. Examples of the gas permselective hollow fiber membrane include a three-layer structure membrane having a non-porous separation layer made of polyurethane.

  The gas separation means 14 is arrange | positioned in the biological treatment tank 12 so that a process target object may be contacted. For example, when the processing target is liquid, the processing target is disposed in the biological processing tank 12 at a position immersed in the processing target. When the processing target is solid, the processing target is stored in the biological processing tank 12. It is placed at a position where it is buried in an object.

  The decompression means 16 is not particularly limited as long as the inside of the gas separation means 14 can be decompressed, and examples thereof include a suction pump.

  Examples of the microorganism supporting mechanism 18 include a separation membrane provided with a microorganism supporting mechanism having high bioadhesiveness on the membrane surface or in the vicinity of the membrane surface. The microorganism supporting mechanism 18 is a porous body having a high specific surface area and / or a material to which microorganisms are easily attached, and carbon fiber is preferable. Organisms such as anaerobic microorganisms may be attached to the microorganism-supporting mechanism 18 in advance.

  The gas storage means 22 is not particularly limited as long as it can store the separated and recovered gas, and examples thereof include an aluminum bag and a pressure vessel.

Next, a biological treatment method using the biological treatment apparatus 10 will be described.
A processing object is put in the biological treatment tank 12, the processing object is biologically processed, and gas is generated. At the same time, the pressure reducing means 16 is operated to reduce the pressure in the gas separating means 14, and the gas generated in the object to be processed is permeated and separated. The gas discharged from the gas discharge port 20 and the decompression means 16 in the upper part of the biological treatment tank 12 is collected by the gas storage means 22. While the biological treatment of the object to be treated is continued, the organism adheres to the microorganism carrying mechanism 18 and a biological layer is formed on the surface of the gas separation means 14.

The treatment object may be anything that generates gas by biological treatment, and examples thereof include waste and wastewater, sewage, sewage sludge and the like in agriculture, livestock industry, fishery industry, and food industry. The object to be treated may be solid or liquid.
Examples of the biological treatment include a treatment of fermenting an organic substance contained in the object to be treated by anaerobic microorganisms under anaerobic conditions.

Examples of the anaerobic microorganism include microorganisms such as methanogenic archaea.
When performing biological treatment, microorganisms may be newly added to the object to be treated, or microorganisms that are originally present in the object to be treated may be used.
Further, by forming a biological layer on or near the surface of the gas separation means 14, it becomes easy to permeate and separate the gas generated by the biological reaction in the biological layer through the separation membrane. Further, the inner side of the biological layer, that is, the side closest to the separation membrane in the biological layer is likely to be more highly anaerobic, and the biological treatment activity of the treatment target is improved. The biological layer may be formed naturally during biological treatment of the object to be treated, or the gas separation means 14 in which the biological layer is formed in advance may be used.

In the biological treatment apparatus 10 described above, the gas separation means 14 is disposed in the biological treatment tank 12 so as to come into contact with the treatment object, and thus is consumed or remains in the treatment object. The recovered gas can be recovered.
Further, in the biological treatment method described above, the gas separation means is brought into contact with the treatment object, so that the gas that has been consumed or remained in the treatment object can be recovered.

(Second Embodiment)
FIG. 2 is a block diagram showing another example of the biological treatment apparatus of the present invention. The same parts of the biological treatment apparatus 30 as those of the biological treatment apparatus 10 are denoted by the same reference numerals and description thereof is omitted. The biological treatment apparatus 30 includes a biological treatment tank 32, a gas separation means 34 disposed in the biological treatment tank 32, a decompression means 16 connected to the gas separation means 34, and a surface of the gas separation means 34 or in the vicinity of the surface. The provided microorganism supporting mechanism 36, the gas discharge port 38 at the top of the biological treatment tank 32, the gas storage means 22 for storing the gas discharged from the decompression means 16, and the processing target logistics on the bottom side of the biological treatment tank 32 An inlet 40 (hereinafter referred to as an inflow port 40) and an upper processing target distribution outlet 42 (hereinafter referred to as an outflow port 42) are provided.

The biological treatment tank 32 is a so-called UASB (Up-flow Anaerobic Sludge Blanket) reactor, and the treatment object flowing in from the inlet 40 provided on the bottom side of the biological treatment tank 32 flows out from the outlet 42 on the upper side. Then, the processing object that has flowed out flows again from the inlet 40 and circulates in the biological treatment apparatus 30. The shape of the biological treatment tank 32 is not particularly limited, and shapes according to various uses can be used.
The biological treatment tank 32 is suitable when the object to be treated is liquid.

The gas separation means 34 has a separation membrane that allows gas to pass therethrough.
Examples of the gas separation means 34 include known separation membrane modules (hollow fiber membrane modules, flat membrane modules, etc.).
The hollow fiber membrane module includes a plurality of hollow fiber membranes (separation membranes 44) and an air collection tube 46, and is fixed to the air collection tube 46 in a state where at least one end of the hollow fiber membrane communicates with the air collection tube 46 It is. Similarly, the other end of the hollow fiber membrane may be fixed in a state where it communicates with the air collecting tube, or the end may be sealed, or may be folded in a loop shape. .

  The hollow fiber membrane is preferably a water-impermeable hollow fiber membrane because it is easy to separate and recover a gas that does not contain moisture even when biologically treating an object to be treated with a high moisture content. The same thing as what was mentioned in the apparatus 10 is mentioned.

  The hollow fiber membrane is preferably a gas permselective hollow fiber membrane from the viewpoint that it is easy to separate and recover useful gases such as hydrogen and methane at a high concentration. The same can be mentioned.

  The gas separation means 34 is arrange | positioned in the biological treatment tank 32 so that it may be immersed in a process target object. The gas separation means 34 is preferably arranged so as not to hinder the flow of the processing object. In addition, when a biological layer is formed on the surface of the gas separation means or in the vicinity of the surface, the thickness of the biological layer to be formed may be taken into consideration so as not to disturb the flow of the processing object.

  The microorganism supporting mechanism 36 can be the same as the microorganism supporting mechanism 18 in the biological treatment apparatus 10.

Next, a biological treatment method using the biological treatment apparatus 30 will be described.
An object to be treated is placed in the biological treatment tank 32, the object to be treated is biologically treated, and gas is generated. At the same time, the pressure reducing means 16 is operated to reduce the pressure in the gas separating means 34, and the gas generated in the object to be processed is permeated and separated. The gas discharged from the gas discharge port 38 and the decompression means 16 in the upper part of the biological treatment tank 32 is recovered by the gas storage means 22. While the biological treatment of the object to be treated is continued, the organism adheres to the microorganism carrying mechanism 36 and a biological layer is formed on the surface of the gas separation means 34.

Examples of the processing target include liquids such as waste water and sewage among those mentioned in the first embodiment. Examples of the biological treatment include a treatment of fermenting an organic substance contained in the object to be treated by anaerobic microorganisms under anaerobic conditions.
Examples of the anaerobic microorganism include the same microorganisms as those mentioned in the first embodiment. When performing biological treatment, microorganisms may be newly added to the object to be treated, or microorganisms that are originally present in the object to be treated may be used.
Further, by forming a biological layer on or near the surface of the gas separation means 34, it becomes easy to permeate and separate the gas generated by the organism in the biological layer. In addition, the inside of the biological layer tends to be more highly anaerobic, and the biological treatment activity of the treatment object is improved.

In the biological treatment apparatus 30 described above, since the gas separation means 34 is disposed in the biological treatment tank 32 so as to be immersed in the treatment object, it may be consumed or remain in the treatment object. The recovered gas can be recovered.
Further, in the biological treatment method described above, since the gas separation means is immersed in the treatment object, the gas consumed or remaining in the treatment object can be recovered.

In the biological treatment apparatus and biological treatment method of the present invention, the biological treatment is performed while taking out the generated gas directly from the treatment target, so that the gas concentration in the treatment target is reduced and the biological treatment activity is increased. An effect is also obtained.
The biological treatment apparatus of the present invention may be used as a waste treatment apparatus such as waste or waste water, or may be used as a gas production apparatus for producing a specific gas from a treatment target.

  In addition, the biological treatment apparatus of this invention is not limited to the apparatus illustrated in FIG.1 and FIG.2. For example, a biological treatment apparatus including a plurality of biological treatment tanks 32 illustrated in FIG. 2 and connecting the outlet 42 and the inlet 40 of the adjacent biological treatment tank 32 may be used.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited by the following description.
In this embodiment, the biological treatment apparatus 10 illustrated in FIG. 1 is used. As the biological treatment tank 12, a rectangular biological reaction reactor having a length of 100 mm × width of 200 mm × height of 300 mm and an effective volume of 6 L was used.

Further, as the gas separation means 14, the following hollow fiber membrane module having a plurality of hollow fiber membranes and an air collection tube was used.
The hollow fiber membrane has a three-layer structure in which a polyurethane gas separation layer (thickness 1 μm) is sandwiched between polyethylene porous support layers (thickness 20 μm), and a gas-selective hollow having an outer diameter of 280 μm. A thread membrane (Mitsubishi Rayon Co., Ltd.) was used. The effective membrane area of the hollow fiber membrane was 0.1 m ² .

As a treatment target, simulated wastewater having the following composition was used.
mg / L
NaHCO ₃ 1000
K ₂ HPO ₄ 50
(NH ₄ ) ₂ HPO ₄ 28
KCl 28
NH ₄ Cl 32
FeCl ₃ · _6H 2 O 16
MgCl ₂ · 6H ₂ O 32
MnSO ₄ · _6H 2 O 0.2
CuSO ₄ · _6H 2 O 0.2
CoCl ₂ · _{6H 2} O 0.2
Ni 0.2
Zn 0.2
Powdered milk 1250
Anaerobic microorganisms that were originally present in the treatment object were used without newly adding anaerobic microorganisms to the treatment object.

[Example 1]
Using the biological treatment tank 10, the simulated wastewater was treated under the conditions of a treatment wastewater amount of 2 L / day, a treatment time of 5 days, and a treatment temperature of 35 ° C. Further, during the treatment period, the simulated waste water flowing out from the outlet 12 was circulated in the biological treatment tank 10 at 8 L / min so as to flow in from the inlet 11. During the treatment period, the inside of the hollow fiber membrane as the separation membrane 21 was decompressed to 0.05 MPa by a decompression pump (not shown).
Table 1 shows the results of gas chromatographic analysis of the composition of the gas extracted from the hollow fiber membrane module during treatment of the simulated wastewater.

[Comparative Example 1]
A biological treatment is carried out in the same manner as in Example 1 except that the gas released from the simulated wastewater, which is the treatment target, into the gas phase is taken out from the gas outlet 13 provided in the upper part of the biological treatment tank 10. The composition of the resulting gas was measured.

As shown in Table 1, in Example 1, the gas that was consumed or remained in the simulated wastewater by the anaerobic microorganisms could be separated. Moreover, the ratio of methane gas in the obtained gas was high, and the target gas could be obtained with high selectivity.
On the other hand, in Comparative Example 1, the gas that was consumed or remained in the simulated wastewater could not be separated, and the proportion of methane gas in the obtained gas was small.

  Since the biological treatment apparatus and biological treatment method of the present invention can separate gases that are consumed or remain in the treatment object, the treatment of waste and waste water, and the treatment object It can be suitably used for production of useful gases such as methane gas and hydrogen gas.

It is the block diagram which showed an example of the biological treatment apparatus of this invention. It is the block diagram which showed the other example of the biological treatment apparatus of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Biological treatment apparatus 12 Biological treatment tank 14 Gas separation means 16 Decompression means 30 Biological treatment apparatus 32 Biological treatment tank 34 Gas separation means

Claims (5)

A biological treatment tank for biologically treating the object to be processed to generate gas;
A gas separation means disposed in the biological treatment tank so as to come into contact with the object to be treated, and having a water-impermeable separation membrane that allows gas to pass through;
Decompression means for decompressing the inside of the gas separation means;
Gas storage means for collecting and storing the gas discharged from the decompression means;
A biological treatment apparatus comprising:   The biological treatment apparatus according to claim 1, wherein the gas separation means includes a microorganism supporting mechanism on or near the surface of the separation membrane. The biological treatment apparatus according to claim 1 or 2 , wherein the separation membrane is a gas selective permeable separation membrane. In a biological treatment method for biologically treating a treatment target to generate a gas and recovering the gas,
A gas separation means having a non-permeable separation membrane that allows gas to pass through is brought into contact with the object to be treated, the inside of the gas separation means is decompressed, the gas is separated from the object to be treated, and the separated gas is The biological treatment method characterized by collect | recovering. The biological treatment method according to claim 4 , wherein a biological layer is formed on the surface of the separation membrane.

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