JPH10328527A - Biological deodorization method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filler layer made of sludge generated by biodegradation of volatile organic substances when a sulfur-based odor gas containing volatile organic substances is passed through a filler layer to which microorganisms are attached and biologically deodorized. To prevent clogging, and perform stable and efficient biological deodorization. SOLUTION: The pH of the filler layer is controlled in the range of 1.5 to 4.0. [Effect] At a pH of 1.5 to 4, the activity of bacteria contributing to the decomposition of organic substances is lost, but the activity of bacteria of the genus Thiobacillus contributing to the decomposition of sulfur-based odor components is high. Generation can be prevented and sulfur-based odor components can be selectively biodegraded. Since there is no generation of excess sludge due to biodegradation of organic matter, there is no problem of clogging of the filler layer, and sulfur-based odor components can be stably and efficiently decomposed and removed for a long period of time.

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 deodorizing a sulfur-based odor gas containing a volatile organic substance through a filler layer to which microorganisms have adhered, and more particularly to a method for biodegrading volatile organic substances in a gas. The present invention relates to a method for performing a stable and efficient biological deodorization by preventing clogging of a filler layer by sludge generated in the above.

[0002]

2. Description of the Related Art Conventionally, hydrogen sulfide, methyl mercaptan,
A sulfur-based odor gas containing a sulfur-based odor component such as methyl sulfide is passed through a biological deodorization tower of a filling type in which a filler layer to which microorganisms are attached is formed and treated.

At this time, the sulfur-based odor component is oxidatively decomposed by microorganisms to generate sulfuric acid. For this reason, neutral or alkaline watering is performed continuously or intermittently from the top of the tower in order to neutralize or wash and remove the generated sulfuric acid. Therefore, the pH of the packed bed is about 2 at the lower part of the packed bed where the sulfur-based odor gas flows, due to the generation of sulfuric acid, but the pH becomes higher toward the gas outlet side, and becomes about 7 at the upper part of the packed bed. Has become.

[0004] On the other hand, when biologically treating volatile organic substances, it is necessary to consider the sludge treatment generated by biological treatment. For example, activated sludge is circulated through a more-type washing tower and brought into contact with a gas containing organic substances. Thus, there is a method of dissolving and biologically oxidizing volatile organic substances and treating them. When the volatile organic substance concentration is low, a method is employed in which treatment is carried out in a packed-type biological deodorization tower, and when the clogging of the filler layer due to sludge generation progresses, the filler is replaced. In the filling method, it has been studied to wash and remove the sludge adhering to the filler by spraying water from the top of the tower.

[0005]

By the way, a food factory,
Sulfur-based odor gases emitted from semiconductor factories, beer factories, and the like contain volatile organic substances such as ethanol and ethyl acetate in addition to sulfur-based odor components.

When such a sulfur-based odor gas containing an organic substance is passed through a packed-type biological deodorization tower to carry out biological treatment, sludge is generated in the process of dissolving and biologically treating volatile organic substances, which adheres to the filler. Grow. Then, the filler layer is clogged by the sludge, which causes an increase in pressure loss and a problem such as a short path. In a serious case, ventilation becomes impossible.

[0007] For this reason, conventionally, in order to remove sludge generated by biodegradation of organic matter, the filler layer is washed about every six months.

[0008] The present invention solves the above-mentioned conventional problems, and when a sulfur-based odor gas containing a volatile organic substance is passed through a filler layer to which microorganisms have adhered to deodorize a living organism, it is generated by biodegradation of the volatile organic substance. It is an object of the present invention to provide a biological deodorization method capable of performing stable and efficient biological deodorization by preventing clogging of a filler layer by sludge to be generated.

[0009]

The biological deodorizing method of the present invention is a method for deodorizing a biological material by passing a sulfur-based odor gas containing a volatile organic substance through a filler layer to which microorganisms are adhered. 1.5 in all areas of the packed bed
The control is performed in the range of 4.0 to 4.0.

In the biological deodorization of sulfur-based odor gas, the purpose of deodorization is achieved if only the sulfur-based odor component can be biodegraded, so that it is not necessary to biodegrade organic substances.

At pH 1.5 to 4, the activity of bacteria contributing to the decomposition of organic substances is lost, but the activity of bacteria belonging to the genus Thiobacillus contributing to the decomposition of sulfur-based odor components is high (for example,
The growth pH of farrooxidans and thiooxidans is 2-3, ab
ertis growth pH is 3.5-4, acidophilus growth p
H is 2.5 to 3), which can prevent the generation of sludge due to the biodegradation of organic substances and selectively biodegrade sulfur-based odor components.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the biological deodorizing method of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a system diagram of a biological deodorizing apparatus showing an embodiment of the biological deodorizing method of the present invention.

Reference numeral 1 denotes a biological deodorization tower, which is provided with an odor gas supply pipe 2 and a sprinkling drain pipe 3 at the bottom, and a processing gas discharge pipe 4 at the top. In the tower, packing layers 5A and 5B supporting microorganisms are provided in two stages, and water sprinkling pipes 6A and 6B are provided above the packing layers 5A and 5B. The odor gas introduced into the biological deodorization tower 1 from the air supply pipe 2 flows upward in the tower, and while passing through the filler layers 5A and 5B, the sulfur-based odor components in the gas are biodegraded and treated. Gas is discharged from the discharge pipe 4 to the outside of the system.

[0015] have been sprinkled effluent discharged from the column bottom, drain pot 7, the pipe 8, via the sump 9 is withdrawn from the pipe 10 by the pump P _1, some of watering by a pipe 11 storage tank 1
2 and the remainder is discharged out of the system through the pipe 13.

[0016] watering tank 12, makeup water from line 14 is introduced, the water sprinkling tank 12 by the pump P _2, the pipe 15, 15A, respectively sprinkling pipe 6A through 15B, is fed to 6B.

In the biological deodorization tower 1, since sulfuric acid is generated by the biodegradation of sulfur-based odor components, the sprinkling drainage shows strong acidity.

In the present embodiment, in order to maintain the filler layers 5A and 5B at an acidic pH of 1.5 to 4, this strongly acidic watering drainage is circulated for watering.

That is, in the conventional biological deodorizing apparatus, sprinkling water is discharged to the outside of the system as it is. When the water is circulated for reducing the amount of water discharged, alkali is added to adjust the pH. In the present invention, the entire filler layer is adjusted to pH
This strongly acidic watering drainage is circulated and used as it is in order to maintain it at 1.5 to 4.

In order to maintain the pH of the filler layers 5A and 5B at 1.5 to 4 by adjusting the circulation amount of the sprinkling drainage, a pH meter 7A provided in the drain pot 7 and a circulation pipe 11 of the sprinkling drainage. In conjunction with the automatic valve V provided in the above, the circulation amount of the sprinkling drainage is controlled.

In the present invention, when the pH of the filler layer exceeds 4 even in a part of the filler layer, biodegradation of organic substances occurs in the part of the filler layer having a pH of 4 or more, and the generated sludge blocks the filler layer. When the pH of the filler layer is less than 1.5, the activity of microorganisms that contribute to the decomposition of sulfur-based odor components is impaired. Therefore, the pH of the filler layer is 1.5 to 4, preferably in all regions of the filler layer. Is maintained at 2-4.

As described above, the pH of the entire filler layer is set to 1.5 to
The sprinkling pH for maintaining the pH at 4 depends on the odor gas aeration condition, the sprinkling condition, and the like.
It is about.

The biological deodorizing apparatus shown in FIG. 1 is an example of an apparatus suitable for carrying out the present invention, and does not limit the present invention. For example, the number of filler layers is not limited to two, but may be three.
It may be provided in a step.

In order to maintain the pH of the filler layer, the pH of the filler layer may be directly measured and controlled. However, the relationship between the pH of the filler layer and the pH of sprinkling water is determined in advance. By grasping and controlling the circulation amount of the sprinkling wastewater by measuring the pH of the sprinkling wastewater as shown in FIG. 1, the pH can be adjusted by a simple operation.

[0025]

The present invention will be described more specifically below with reference to examples and comparative examples.

First, a comparative example will be described for convenience of explanation.

COMPARATIVE EXAMPLE 1 An odorous gas having the following composition discharged from a food factory was aerated at a rate of SV = 150 hr ^-1 from the bottom of a biological deodorization tower in which a 1 m-high filler (peat) layer was formed in three stages. As a result, a treated gas having the following composition was obtained stably.

From the top of each filler layer, a pH of 6.7 was measured.
~ 7.2 industrial water was sprinkled. The pH of the filler layer was about 2 at the bottom, gradually increased upward, and was about 7 at the top of the filler layer.

[0029]

[Table 1]

In Comparative Example 1, the pressure loss, which was 40 to 45 mmAq at the beginning of the operation, gradually increased by continuing the operation.
It increased to 60 mmAq.

Then, when the packing material was taken out from the biological deodorization tower and examined, it was found that excess sludge had adhered to the packing material, which blocked the packing material layer and increased the pressure loss.

Since water for industrial use is used for watering the biological deodorization tower and the BOD source is extremely small, it is considered that the cause of the excess sludge is organic matter in odor gas.

Example 1 In Comparative Example 1, a part of the sprinkling water was circulated and used for sprinkling, and water having a pH of 3 to 4 was sprinkled to adjust the pH of the filler layer to a range of 1.7 to 4.0 as a whole. When the treatment was performed in the same manner except that the concentration was maintained, the concentration of the sulfur-based odor component in the treated gas was almost the same as that in Comparative Example 1, and 99.9% or more of the sulfur-based odor component was removed. In addition, no increase in pressure loss was observed even after continuous operation for one year or more, and the pressure loss was 40 to 45 mmAq as in the initial operation.

[0034]

As described above in detail, according to the biological deodorizing method of the present invention, since there is no generation of excess sludge due to biodegradation of organic substances, there is no problem of clogging of the filler layer and sulfur-based odor components can be removed for a long period of time. It can be stably and efficiently decomposed and removed throughout.

[Brief description of the drawings]

FIG. 1 is a system diagram of a biological deodorization apparatus showing an embodiment of a biological deodorization method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Biological deodorization tower 5A, 5B Filler layer 6A, 6B Sprinkler pipe 7 Drain pot 7A pH meter 9 Drain tank 12 Sprinkle storage tank

Claims (1)

[Claims] 1. A method for deodorizing a living organism by passing a sulfur-based odor gas containing volatile organic substances through a filler layer to which microorganisms have adhered, wherein the pH of the filler layer is controlled in the range of 1.5 to 4.0. A biological deodorization method, comprising: