JPH05212238A - Biological treatment of digestion gas - Google Patents

Abstract

PURPOSE:To biologically perform treatment of digestion gas without using chemicals. CONSTITUTION:A packed layer 2 is formed by packing a filler to which microorganisms adhere in the inside of a treatment vessel 1. Digestion gas is introduced into the treatment vessel 1 and brought into contact with absorption liquid circulated to an aeration tank. Hydrogen sulfide and gaseous carbon dioxide contained in the gas are absorbed in the absorption liquid. While the absorption liquid flows down through the inside of the packed layer, the same is decomposed by microorganisms. Gaseous hydrogen sulfide component discharged from the aeration tank is biologically treated in the other treatment vessel 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for biologically treating digestive gas, and more particularly, to a sulfur-based odorous substance such as hydrogen sulfide generated from human waste treatment plant, sewage treatment plant and various other factories, ammonia, The present invention relates to a biological treatment method effective for treating digestive gas containing carbon dioxide and the like.

[0002]

2. Description of the Related Art Digestion gas generated when anaerobically treating a high-concentration organic matter-containing waste liquid such as a human waste treatment plant or a sewage treatment plant sludge treatment system is decarboxylated for the purpose of volume reduction and energy saving for storage, Corrosiveness of combustion gas and 2
Due to the problem of secondary pollution (SOx), it is desulfurized.

For these decarbonation and desulfurization treatments, a cleaning system and an adsorption system are usually adopted.

In recent years, research has been advanced to apply biological methods to gas treatment, and in particular in the field of deodorization, this has been partially implemented.

[0005]

However, in the above-mentioned decarboxylation and desulfurization treatments by the conventional cleaning method and adsorption method, both methods require a large amount of chemicals and the cost of exchanging the adsorbent, and in terms of maintenance. It requires human labor.

Further, the biological treatment method has an advantage that the reaction cost is almost zero because the reaction is carried out by mediating microorganisms growing in the natural world. However, the methods developed so far are usually aerobic microorganisms. Is used, and when treating the anaerobic gas as described above, it is necessary to supply oxygen. Therefore, for a gas such as a digestion gas that is liable to be ignited by the inclusion of an excessive amount of air, it is dangerous to supply excess oxygen, and therefore it is necessary to treat the gas under a completely anaerobic condition or a slightly aerobic condition.

[0007] In the natural world, there are microorganisms capable of desulfurizing (oxidizing hydrogen sulfide and decomposing it as sulfuric acid from gas) under anaerobic conditions. However, when an anaerobic microorganism is used, it may give off an odor, or However, there is a problem in maintenance and economic efficiency such as the need to give energy (for example, light in the case of purple sulfur bacteria) instead of oxygen.

The main components of the digestive gas are methane, carbon dioxide, hydrogen sulfide, ammonia, etc., but when burning this, it is necessary to remove hydrogen sulfide, ammonia in order to reduce SOx and NOx. There is. These components are easily oxidized by microorganisms, but since the microorganisms involved in the reaction are aerobic bacteria, it is necessary to keep the growth environment of the microorganisms aerobic.

The present invention has been made in view of the above points, and an object of the present invention is to provide a biological treatment method for digestive gas, which solves the problems of the conventional biological treatment methods. ..

[0010]

The gist of the present invention for achieving the above-mentioned object is to form a packed bed filled with a packing material on which microorganisms have grown, in the processor, Digestion gas is introduced into the aeration tank and brought into contact with the absorption liquid circulating in the aeration tank to absorb hydrogen sulfide or carbon dioxide gas in the gas into the absorption liquid and decomposed by microorganisms while the absorption liquid flows down in the packed bed. A biological treatment method for digestive gas is characterized in that the odorous components such as hydrogen sulfide and ammonia mainly emitted from the aeration tank are biologically treated in another treatment device.

[0011]

[Function] When the digestive gas introduced into the processing unit is aerated through the packed bed filled with the packing material on which the microorganisms have adhered and brought into contact with a large amount of oxygen-saturated absorption liquid by aeration, the microorganisms in the packed bed are Is the hydrogen sulfide in the gas, utilizing its dissolved oxygen,
Ammonia and the like can be oxidized.

A part of hydrogen sulfide or the like absorbed in the absorbing solution is oxidized by microorganisms adhering to the surface of the packing material while passing through the packed bed, and is mixed into the absorbing solution as sulfuric acid or the like.

When the digestive gas and the absorption liquid are brought into contact with each other, carbon dioxide in the digestion gas is dissolved in the absorption liquid, so that the volume of the gas is reduced and, as a result, the calorific value per unit volume is increased. is there.

The absorbing liquid dropped into the liquid reservoir at the bottom of the processor is
It is circulated and used as an absorbent in a state where it is aerated and saturated with oxygen. Aeration combines the dissolution of oxygen and the deaeration of carbon dioxide dissolved in the absorbent.

Odor components such as hydrogen sulfide and ammonia remaining in the absorption liquid are dispersed during aeration, but these odor components are biologically decomposed and removed under aerobic conditions in another deodorization tower to deodorize them. Emitted as gas.

[0016]

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

FIG. 1 is a schematic block diagram showing an example of an apparatus applied to carry out the present invention on an industrial scale.

The embodiment is a cleaning tower A for absorbing the removal target component in the digestive gas into the absorption liquid, and a deodorization tower for removing the odorous components separated when the absorption liquid is aerated for circulating the absorption liquid. The case where B is installed is shown.

In the figure, 1 is a processing unit that constitutes the washing tower A, and 2 is a packed bed formed in the middle of the processing unit 1, which is filled with a packing material on which microorganisms have grown. Reference numeral 3 denotes a water sprinkler installed in the upper part of the packed bed 2 in the processing device 1 and connected to the liquid supply pipe 4. 5 is an air supply port provided on the side wall of the processor 1 below the packed bed 2, 6 is an exhaust port provided on the top of the processor 1, and 7 is an exhaust port 6.
An eliminator installed near the sprinkler 4 in the vicinity, and a liquid reservoir 8 formed at the bottom of the processor 1.

Reference numeral 9 denotes a processing unit constituting a deodorizing tower B attached to the cleaning tower A, and 10 a packed bed formed in the middle of the processing unit 9, which is filled with a packing material on which microorganisms have grown. Reference numeral 11 denotes a water sprinkler installed in the upper part of the packed bed 10 in the processing device 9, and is connected to the liquid supply pipe 12. 13 is the packed bed 1 in the processor 9.
The draining plate disposed below 0 receives the absorbing liquid falling from the packed bed 10, collects the water in the water collecting groove 14 provided around the inner wall surface of the processing device 9, and discharges it to the outside through the drain pipe 15. It was done like this. 16 is an exhaust port provided at the top of the processor 9
7 is an eliminator arranged near the exhaust port 16 above the sprinkler 11, and 18 is a liquid reservoir formed at the bottom of the processor 9.
The liquid reservoir 18 is partitioned by the liquid reservoir 8 of the cleaning tower A and the partition wall 19, and the aeration gas from the deodorizing tower B side is washed by the cleaning tower A.
Both liquid reservoirs 8 and 18 are communicated with each other by a through hole 20 provided in the lower portion of the partition wall 19 so as not to leak to the side.
Reference numeral 21 denotes an aeration diffuser provided in the liquid reservoir 18 and connected to the air supply pipe 22. Reference numeral 23 is a liquid take-out pipe connected to the liquid reservoir 18, and the liquid take-out pipe 23 is used as a common circulation pump 2
It is connected to the liquid supply pipes 4 and 12 of the water sprinklers 3 and 11 via the No. 4 pipe. Reference numerals 25 and 26 are water sprinkling valves respectively inserted in both liquid supply pipes 4 and 12 for adjusting the water sprinkling amount. 27 is a replenishing liquid supply pipe connected to the liquid reservoir 18, 28 is an overflow pipe connected to the liquid reservoir 8 for keeping the liquid levels of both liquid reservoirs 8 and 18 constant.

In the above structure, the digestion gas is supplied to the air supply port 5.
Is introduced into the treatment device 1 of the washing tower A, and the absorbent liquid sprayed from the water spray device 4 and the packed bed 2 are efficiently in gas-liquid contact with each other to absorb hydrogen sulfide, ammonia, carbon dioxide and the like in the gas. Transfer to liquid. The treated gas has its moisture removed by the eliminator 7, and is then discharged from the discharge port 6 to be guided to the gas holder or the combustion equipment.

The absorbing solution which has absorbed the components to be removed comes into contact with microorganisms growing on the surface or inside of the packed bed while flowing down the packed bed 2, and a part of hydrogen sulfide and the like in the absorbent is oxidized to generate sulfuric acid and the like. Then, it falls into the liquid reservoir 8 together with the absorbing liquid that drops from the packed bed 2. The stored liquid that has fallen into the liquid storage portion 8 in this way passes through the through holes 20 of the partition wall 19 and the liquid storage portion 18 of the deodorization tower B.
And is aerated by the sprinkling pipe 21. During this aeration, the gas component absorbed from the liquid stored in the liquid reservoir 18 is released. This effluent gas contains odorous components such as hydrogen sulfide and ammonia, which are efficiently decomposed by aerobic microorganisms while passing through the packed bed 10, and the odorized processing gas is removed by the eliminator 17. Moisture is removed and the air is discharged from the discharge port 16, or finishing treatment is performed if necessary. The absorbing liquid that has fallen from the packed bed 10 is collected in the water collecting groove 14 by the water draining plate 13 and is discharged from the discharge pipe
It is discharged to the outside of the vessel via 5. The stored liquid in the liquid reservoir 18 is saturated with oxygen again by aeration, and is sent to the water sprinklers 3 and 11 by the circulation pump 24 for circulation. In this way, by aeration, saturating oxygen, and circulating the absorbing solution, decomposition by microorganisms can be performed under microaerobic conditions. Further, a part of this liquid is used as water necessary for the growth of organisms in the packed beds 2 and 10.

However, in carrying out the above method, the following are specific items.

(A) As the packing material used in the packed bed 2 of the washing tower A, it is desirable that the organisms easily grow and the gas-liquid contact efficiency is high. Usually, a corrugated plate is used, but it is porous. It may be ceramic, granulated slag, peat, sponge or the like, or a polymer gel or the like in which a group of microorganisms that decompose the components to be removed are activated or attached. The packing material used for the packed bed 10 of the deodorization tower B may be any packing material suitable for biological deodorization, and an adsorbent, a porous ceramic, a peat, a sponge, granulated slag, or the like is used. Further, it may be a polymer gel or the like having a microorganism group that decomposes the removal target component bound or attached thereto.

(B) In the above-mentioned embodiment, the cleaning tower A and the deodorization tower B are shown to have the liquid reservoirs 8 and 18 partitioned by the partition wall 19. However, both liquid reservoirs 8 and 18 are separated. The structure may be such that they are independent of each other and are connected by a communication pipe.

(C) The sewage secondary treated water is usually used as the absorbent used for sprinkling water, but it may be industrial water, ground water or well water. In addition, since the microorganisms that oxidize hydrogen sulfide are aerobic, the oxygen required for the microorganisms is in the form of dissolved oxygen in the water sprinkled by previously aerating the absorbent with a gas containing oxygen and saturating the oxygen. Give in. This watering may be intermittent, but it is usually continuous.

(D) Although the sprinkling liquid in the deodorizing tower B can be reused, the pH is lowered by the sulfuric acid generated by the biodegradation of hydrogen sulfide, so that the neutralization operation is complicated and economical. It is preferable that the drainage plate 13 collects water and discharges it outside the vessel.

(E) In the deodorization tower B, since the aeration gas released from the stored liquid during aeration is deodorized, the gas used for aeration may be an odor gas as long as it contains oxygen. If the aerobic odor gas generated at the place is used, it is possible to deodorize the aerobic odor at the same time.

(F) Replenishment of the liquid to the liquid reservoirs 8 and 18 may be performed by detecting the water level of the stored liquid, but normally, a fixed amount is continuously supplied from the replenishing liquid supply pipe 27 and the overflow pipe is supplied. Overflow from 28.

(G) The packed bed 10 of the deodorization tower B may be a one-layer type as in the embodiment, but it is a multi-layered type in which a plurality of packed layers are provided in multiple stages. More effective deodorization can be achieved by setting conditions that are advantageous for the growth of microorganisms that decompose odorous components. Also, other formats may be used.

(H) In the above-mentioned embodiment, the biological deodorizing tower is used from the viewpoint of maintenance and economy, but this may be a conventional physicochemical deodorizing tower.

[0032]

As described above, the present invention has the following effects.

(A) Since the digestion gas is treated without using chemicals, the operating cost is low. (b) Since the absorbed gas component is further biologically treated, no secondary pollution occurs.

(C) As the aeration gas, an aerobic odor gas generated elsewhere can be used. In this case, the odor gas can be deodorized at the same time.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an example of a processing apparatus to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Treatment device (washing tower) 2 ... Packing layer 3 ... Sprinkler 8 ... Liquid storage part 9 ... Treatment device (deodorization tower) 10 ... Packing layer 11 ... Sprinkler 18 ... Liquid storage part 21 ... Diffusing pipe 24 ... Circulation pump A ... Washing tower B ... Deodorization tower

Claims (1)

[Claims] 1. A gas is produced by forming a packed bed filled with a packing material on which microorganisms have grown in a processing device, introducing digestive gas into the processing device, and bringing the digested gas into contact with an absorption liquid circulating in an aeration tank. Absorbing hydrogen sulfide and carbon dioxide in the absorbing liquid, decomposed by microorganisms while the absorbing liquid flows down in the packed bed, and mainly dissipates the odorous components of hydrogen sulfide and ammonia emitted from the aeration tank. A biological treatment method for digestive gas, which is characterized by biologically treating the digester gas.