JP2007136252A - Deodorization method and apparatus for odor gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deodorization method for an odor gas capable of exhibiting an excellent deodorization effect even if a concentration is extremely varied regarding an odor component of the odor gas generated from a sewage treatment facility or the like, reducing an operation cost and maintaining an excellent treatment performance over a long period of time, and an apparatus. <P>SOLUTION: In the treatment method for the odor gas, organism deodorization of the odor gas is performed using a microorganism fixing carrier and the organism deodorization treatment gas is treated by adsorption using an activated carbon. After the odor gas is previously subjected to a water-washing treatment, the organism deodorization treatment is performed. The pH of washing water for previously water-washing-treating the odor gas is maintained to approximately 3 or more and the washing water used for previously water-washing-treating the odor gas is treated while using water-spraying required for the organism deodorization. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an odor gas deodorization method and apparatus that can efficiently remove unpleasant odor components in gas generated from sewage treatment plants, human waste treatment plants, food factories, chemical factories, and the like.

  Odor gas generated from treatment facilities such as sewage and human waste and various factories is increasingly demanded to improve the living environment, and deodorizing measures are required. In particular, odorous gas generated at sewage treatment plants, etc. contains a relatively large amount of hydrogen sulfide as an odorous component, and other sulfur-based odorous components such as methyl mercaptan, methyl sulfide, and methyl disulfide, and basic substances such as ammonia. Since gas is contained, it is necessary to remove these odor components.

Various methods such as a chemical cleaning method, an adsorption method, a biological deodorization method, and an ozone oxidation method are known as methods for deodorizing odor gas containing these odor components. Of these, the activated carbon adsorption method using activated carbon as an adsorbent and the packed tower type biological deodorization method which is one of the biological deodorization methods are often used.
The activated carbon adsorption method uses the adsorption action of activated carbon and has the feature that many odorous components can be adsorbed and removed. However, it is necessary to frequently replace activated carbon with reduced adsorption capacity, resulting in high operating costs. There is a problem of becoming.

The packed tower type biological deodorization method is a method of decomposing and removing odor components in odor gas by passing odor gas through a biological carrier packed bed (hereinafter simply referred to as packed bed) provided in the packed tower.
This packed tower type biological deodorization method is an economical treatment method with low running cost because it does not cause the problem of performance degradation due to long-term use of the adsorbent unlike the activated carbon adsorption method.

  However, the packed tower type biological deodorization method has various problems because it uses a microorganism. For example, it is necessary to keep the surface of the carrier wet in order for the microorganisms to grow in the packed bed. For this reason, a humidifier such as a spray tower that sprays spray water from the upper part of the packed tower type biological deodorization tower (hereinafter, simply referred to as a biological deodorization tower) is equipped with a humidifying device such as a spray tower, and the odor gas that flows to the biological deodorization tower. A method for saturating the water concentration in the water has been proposed (see, for example, Patent Document 1).

  In addition, when the temperature of the gas to be treated decreases in winter, the decomposition activity of malodorous substances by microorganisms decreases. For this reason, a method has been proposed in which the odor gas is passed through a scrubber that sprays spray water having a temperature higher than that of the odor gas, brought into contact with the scrubber water, the temperature of the odor gas is raised in advance, and then supplied to the biological deodorization tower. (For example, refer to Patent Document 2).

  Furthermore, in the packed tower type biological deodorization method, easily degradable odor components such as hydrogen sulfide are relatively easy to remove, but difficult degradable odor components such as methyl sulfide and methyl disulfide are difficult to remove. Moreover, it cannot follow the fluctuation | variation of an extreme odor density | concentration. For this reason, a method is generally employed in which an activated carbon adsorption tower is provided after the biological deodorization tower.

  However, even if the biodeodorization tower and the activated carbon adsorption tower are used in combination, they cannot cope with a high concentration of odor components or when there is an extreme fluctuation, so a method of providing another treatment tower has been proposed. (For example, refer to Patent Document 3).

In this method, a plurality of biological deodorization towers and adsorption towers are provided, and a catalyst treatment tower is provided between them to oxidatively decompose odor components.
Since this method has a large number of treatment towers, it has good deodorization performance, but it requires an expensive reaction tower packed with a catalyst between the biological deodorization tower and the activated carbon adsorption tower, and problems such as catalyst deterioration. There is also.

JP 2004-24996 A Japanese Patent Laid-Open No. 2001-137552 JP 11-47554 A

  The present invention has been made in view of the circumstances as described above, and its purpose is to provide an excellent deodorizing effect even when the concentration of the odor component of odor gas generated from a sewage treatment facility or the like varies significantly. It is to provide a deodorizing method of odor gas and a deodorizing apparatus having such a function, which can reduce the operating cost and can maintain excellent processing performance for a long period of time.

The present invention has been made to achieve the above-described problems, and has been solved by the following means.
In a deodorizing method for odor gas generated from sewage treatment facilities, etc., the odor gas is biologically deodorized using a microorganism-immobilized carrier, and the biological deodorized gas is adsorbed using activated carbon. The odor gas was previously washed with water and then subjected to biological deodorization treatment.

  Moreover, the pH of the wash water for pre-washing the odor gas is maintained at about 3 or more, and the wash water used for pre-washing the odor gas is used for watering necessary for biological deodorization. It is also characterized.

  An apparatus for deodorizing odorous gas generated from a sewage treatment facility, etc., comprising a biological deodorization tower filled with a microorganism-immobilized carrier for biologically treating odorous gas, and an activated carbon adsorption tower filled with activated carbon at the subsequent stage of the biological deodorization tower In the odor gas deodorization apparatus to be installed, a washing tower for previously washing the odor gas with water is provided in front of the biological deodorization tower.

  In addition, a neutralizing agent supply device for adjusting the pH of the cleaning water supplied to the cleaning tower is also provided.

Gas generated from sewage treatment facilities, etc. by using the deodorization method and apparatus of the present invention that removes hydrogen sulfide and the like in odor gas that can be easily treated by water washing in advance and biologically treats and adsorbs the treated gas. Even if the concentration of the odor component varies greatly, the odor component can be stably removed.
In addition, by washing with water in advance, the influence of the biological deodorization tower on living organisms can be avoided, and the life of the activated carbon of the activated carbon adsorption tower can be extended. Can be processed.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications.
FIG. 1 is a schematic view showing a configuration example of an apparatus for carrying out the odor gas deodorizing method according to the present invention. As shown in FIG. 1, the deodorization apparatus 20 deodorizes, for example, odor gas generated from sewage treatment equipment, and the odor gas is, for example, hydrogen sulfide, methyl mercaptan, methyl sulfide, disulfide as odor components. Contains methyl, ammonia, etc.

The deodorizing apparatus 20 includes a washing tower 1 for preliminarily washing the odor gas to remove a part of the odor components, a biological deodorization tower 2 for biologically deodorizing the remaining odor components, and an activated carbon adsorption tower 3 for performing activated carbon adsorption treatment.
It has.

A gas to be processed which is an odor gas is supplied to the lower part of the cleaning tower 1 through the gas to be processed introducing pipe 100 and is discharged from the upper part of the cleaning tower 1.
Inside the cleaning tower 1, a packed layer 4 such as ceramics or plastics for improving the contact between the gas to be treated and the cleaning water is disposed. Washing water is supplied to the packed bed 4 through the washing water supply pipe L1 and the sprinkling pipe 5, whereby most of hydrogen sulfide and ammonia in the gas to be treated are absorbed and removed.

In the embodiment shown in the figure, the case where the packed bed 4 is provided in the cleaning tower 1 is shown, but the packed bed 4 is omitted by providing a spray nozzle or the like for spraying fine droplets on the water spray pipe 5. Is also possible.
In addition, industrial water is usually used as the washing water. However, when the pH is lowered by using it, the absorption capacity of hydrogen sulfide and the like is lowered. If the pH is about 2 to 3 or less, the washing water is neutralized. An alkali agent such as sodium hydroxide is added to the neutralizing tank 6 from the neutralizing agent supply device 7 and neutralized so that the pH becomes about 3 or higher, and then supplied to the upper portion of the washing tower 1.

A suitable processing speed of the gas to be processed in the cleaning tower 1 is about SV300 to 1000H- ¹ . A suitable liquid gas ratio (L / G) is about 5 to 10 l / m ³ .
Under such processing conditions, the washing tower 1 removes about 70 to 80% of hydrogen sulfide and about 40 to 50% of ammonia.

Next, the cleaning tower processing gas is introduced into the lower part of the biological deodorization tower 2 through the gas feed pipe 101, and the biological deodorization tower processing gas is discharged from the upper part of the biological deodorization tower 2.
A packed bed 8 is disposed inside the biological deodorization tower 2. The packed layer 8 is filled with a carrier such as ceramic or plastic to which microorganisms adhere.

Activated sludge treated water or the like is supplied to the packed bed 8 through a water spray tube 9, whereby microorganisms that decompose odorous components grow. Since the cleaning tower processing gas passes through the packed bed 8, the odor component in the cleaning tower processing gas is decomposed and deodorized.
Since the treatment speed of the biological deodorization tower 2 is relatively slow, the size of the biological deodorization tower 2 is usually determined to be a treatment speed of about SV100 to 200H- ¹ .

  In this biological deodorization tower 2, hydrogen sulfide is usually about 90%, methyl mercaptan is about 85%, methyl sulfide and methyl disulfide are about 70 to 80%, and ammonia is about 40% with respect to the inlet gas of the biological deodorization tower 2. Is removed. Among them, hydrogen sulfide can be efficiently removed as in the cleaning tower 1.

  In the method of the present invention, since the washing tower 1 is provided in front of the biological deodorization tower 2, it is possible to reduce the size of the biological deodorization tower 2 that is normally large to about 1/2.

In addition, the activated sludge treated water or the like sprayed to the packed bed 8 is led from the activated sludge treated water tank 10 such as an activated sludge treatment facility (not shown) to the sprinkler pipe 9 through the sprinkler supply pipe L3 by the sprinkler supply pump P3. .
Further, the bottom of the biological deodorization tower 2 is a water reservoir 11 for storing water spray falling from the packed bed 8, and the stored water is discharged out of the system for processing, or the stored water is optimal for microorganisms. After adjusting so that it may become pH, it may pump up with a circulation pump (not shown), and you may make it spray the filling layer 8 from the sprinkling pipe 9. The water spray is also used for cleaning the packed bed 8.

If the odor component is low in the biological deodorization tower 2, microorganisms that use the odor component as a nutrient source will be killed. Therefore, the absorption liquid that is used in the cleaning tower 1 and absorbs hydrogen sulfide and the like is used as a nutrient source for microorganisms at night. When the odor concentration is low, it can be sent to the upper part of the biological deodorization tower 2 through the liquid feed pipe L2 and sprinkled for treatment.
In the embodiment shown in FIG. 1, the absorbing liquid that has been used in the cleaning tower 1 and absorbed hydrogen sulfide or the like is directly supplied to the upper part of the biological deodorization tower 2. You may make it supply to the upper part of.

  In the biological deodorization tower 2, an embodiment in which only one packed bed 8 is used has been described. However, two or more packed beds 8 or two or more biological deodorizing towers 2 can be provided, It is also possible to provide a sprinkler tube 9 above each packed bed.

  The processing gas in the biological deodorization tower 2 is further sent to the activated carbon adsorption tower 3 through the gas supply pipe 102 and processed. Since the treatment gas of the biological deodorization tower 2 is saturated in moisture and has a high moisture content, it is sent to the mist separator 12 through the gas feed pipe 102, and after the mist in the gas is removed, the gas feed pipe 103 is To the activated carbon adsorption tower 3.

  In the process in which the processing gas from the biological deodorization tower 2 sent to the activated carbon adsorption tower 3 passes through the packed bed 13 of activated carbon, the methyl sulfide remaining without being absorbed or decomposed by the cleaning tower 1 or the biological deodorization tower 2 Refractory odor components such as methyl sulfide are also almost completely removed.

In general, odor gas rarely has a constant generation amount of odor components, and changes depending on the season, weather, and the like. Further, in the sludge system of a sewage treatment facility, the odor concentration increases when the sludge flows into the sludge storage tank or when the sludge is transferred to a dehydrator or the like. In the case of odor fluctuation of several times, considerable treatment is possible with only the biological deodorization tower 2, but normally, sludge odor with about 10 to 100 ppm of H ₂ S and about 1 to 5 ppm of NH ₃ With gas, it may reach about 10 times the normal time at the peak. In the case of such a high-concentration odor gas, the biological deodorization tower 2 cannot complete the treatment, and a large load is applied to the activated carbon adsorption tower 3 in the subsequent stage, thereby shortening the life of the activated carbon.

  By providing a small and inexpensive washing tower 1 in front of the biological deodorization tower 2, the concentration of the odorous gas flowing into the biological deodorization tower 2 can be adjusted even when the odor concentration fluctuates and the odor concentration becomes high. Leakage of odor components in the tower 2 can be kept low. Moreover, it is possible to extend the lifetime of the activated carbon of the latter activated carbon adsorption tower 3 several times longer.

  The prior art (Patent Document 1 and Patent Document 2) provided with a washing tower type humidifier and temperature control device in the front stage of the biological deodorization tower simply increases the function of the biological deodorization tower in the latter stage. Although temperature control is performed, the method of the present invention has a feature that the load of the biological deodorization tower 2 in the subsequent stage can be greatly reduced by removing most of hydrogen sulfide and the like. Of course, the odor gas can be humidified, and the temperature of the odor gas can be increased by using high temperature washing water.

  As described above, in the present invention, the odor gas is introduced into the deodorization apparatus 20 including the biological deodorization tower 2 and the activated carbon adsorption tower 3 after the odor gas is previously washed in the washing tower 1, thereby increasing the concentration of the odor gas. Even if it fluctuates, stable high deodorizing performance can be maintained. Moreover, since the life of activated carbon can be greatly extended, economical odor gas treatment is possible.

  Further, in the present invention, the operation of the washing tower 1 is stopped at the normal time when the odor concentration is low, only the biological deodorization tower 2 and the activated carbon adsorption tower 3 are operated, the treated gas is discharged to the atmosphere, the inflow of sludge, The cleaning tower 1 may be operated only when the odor becomes high such as during sludge transport and stirring, and the treatment gas of the cleaning tower 1 may be further processed by the biological deodorization tower 2 and the activated carbon adsorption tower 3.

It is the schematic which shows the structural example of the deodorizing apparatus concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Washing tower 2 Biological deodorization tower 3 Activated carbon adsorption tower 4 Packing layer 5 Sprinkling pipe 6 Neutralization tank 7 Neutralizing agent supply device 8 Packing layer 9 Sprinkling pipe 10 Activated sludge treatment water tank 11 Water reservoir 12 Mist separator 13 Packing bed

Claims (5)

  In the odor gas treatment method in which the odor gas is biologically deodorized using the microorganism-immobilized carrier and the biological deodorization treatment gas is adsorbed using activated carbon, the odor gas is washed with water in advance and then the biological deodorization treatment is performed. Characterized odor gas deodorization method.   2. The method of deodorizing odor gas according to claim 1, wherein the pH of the wash water for preliminarily washing the odor gas is maintained at about 3 or more.   3. The method of deodorizing odor gas according to claim 2, wherein the odor gas is preliminarily washed to be used for water spraying necessary for biological deodorization.   In the odor gas deodorization apparatus in which a biological deodorization tower filled with a microorganism-immobilized carrier for biological treatment of odor gas and an activated carbon adsorption tower filled with activated carbon is installed in the subsequent stage of the biological deodorization tower, the odor gas is washed in advance with water. An odor gas deodorizing apparatus characterized in that a tower is provided in front of a biological deodorization tower. 5. A deodorizing apparatus for odor gas according to claim 4, further comprising a neutralizing agent supply device for adjusting the pH of the cleaning water supplied to the cleaning tower.

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