JP3063103B2 - Biological deodorization method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a biological deodorizing method, and more particularly to a method for biologically deodorizing an odor generated from a human waste treatment plant, a sewage treatment plant, and various factories. In particular, in biological deodorizers targeting sulfur-based malodorous substances, stabilize the microflora in the equipment, prevent a reduction in odor decomposition activity, enable high-load treatment, and reduce the amount of water used for watering. The present invention relates to a method for greatly reducing biological deodorization.

[Prior art] Conventionally, to deodorize odorous gas from night soil, sewage and other wastewater, a column is filled with soil, peat, activated sludge, etc., and odorous gas is supplied to the column to allow microorganisms to proliferate. Processing was being performed.

There is a sulfurous odor component as an odor component of odor gas such as night soil and sewage. Hydrogen sulfide (hereinafter, referred to as “H ₂ S”), methyl mercaptan (hereinafter, referred to as “MM”), and methyl sulfide (hereinafter, “DM”)
S ". ) And the like, and attempts have been made to remove these sulfur odorants by biological deodorization.

These sulfur odorants are decomposed by living organisms,
Produces sulfuric acid. As a result, the pH in the device decreases, exhibits strong acidity, inhibits the biological reaction of microorganisms, and makes biological deodorization impossible. Conventionally, in a packed tower type biological deodorizing apparatus, neutralized water is neutralized or washed by spraying neutral water continuously or intermittently from the upper part of the apparatus in order to prevent such acidification. (Japanese Patent
62-7425). The sprinkling amount and sprinkling frequency of this sprinkling water were determined as appropriate by measuring the pH of the washing wastewater stored in the lower part of the apparatus.

[Problems to be Solved by the Invention] By the way, as a result of the inventor's intensive study on the method of deodorizing sulfur-based odorous substances, the bacteria that decompose each sulfur-based odorous substance differ from one substance to another, and the applicable It was found that the pH range also varied from bacteria to bacteria. Furthermore, it became clear that if such a pH range is maintained, deodorization can be achieved even when the amount of odor gas supplied to the treatment tower is increased.

However, in the conventional method, the pH value of
Since watering is controlled only by water, it is not sufficient to maintain the inside of the apparatus at a pH environment suitable for each bacterium. For this reason, the processing efficiency is poor, high-load processing cannot be performed, and low-load processing has been forced.

That is, when biologically deodorizing sulfur-based odor substances, H ₂ S, M
M and DMS are easily degraded in this order, and each decomposes different bacteria. Therefore, when the odor gas is passed through the biological packed tower in a transient manner, the H ₂ S decomposition layer, MM
A decomposition layer and a DMS decomposition layer are formed, and the respective decomposition bacteria are segregated. This is because each odor-decomposing bacterium loses its decomposing ability when an odor component more easily decomposed than the odor component is present. In other words, DMS degrading bacteria
This is because in the presence of M and H ₂ S, MM-degrading bacteria lose the resolution in the presence of H ₂ S. For this reason, in the biological packed tower, segregation of bacteria as described above is formed, and is treated individually.

However, when the environment in the packed tower is incompatible with a specific decomposing bacterium, the growth and decomposition activity of the bacterium are suppressed, and the treatment efficiency deteriorates.

Therefore, in order to treat odor gas efficiently, it is necessary to stably maintain the decomposition bacteria of each odor component and to provide an environment suitable for the growth and decomposition activity of each microorganism.

However, conventionally, there has not been provided a biological treatment method capable of segregating bacteria decomposing the respective odor components and providing a suitable environment.

The present invention solves the above-mentioned conventional problems, and in deodorizing the odorous gas by biodegrading it with a biological deodorizing device, stabilizes the bacterial flora in the device, improves the growth and decomposition activity of the bacteria, and sprays water. It is an object of the present invention to provide a biological deodorization method capable of performing an efficient treatment at a low cost by reducing the amount of water used for water.

[Means for Solving the Problems] The biological deodorization method of the present invention is directed to a hydrogen sulfide decomposition packed bed carrying hydrogen sulfide decomposition microorganisms, and a methyl mercaptan carrying methyl mercaptan decomposition microorganisms. A method for deodorizing a packed bed for decomposition and a packed bed for decomposition of methyl sulfide carrying methyl sulfide-decomposing microorganisms by upward flow, wherein the pH of the packed bed for decomposition of methyl mercaptan and the packed bed for decomposition of methyl sulfide are adjusted. 6
８8 and the pH of the packed bed for hydrogen sulfide decomposition.
Is maintained at 2 to 4.

By maintaining such a pH range, deodorization can be performed even if the amount of odor gas supplied to the treatment tower is increased. That is, in general, in biological deodorization, the air supply is often performed at a space velocity (SV) of about 40 hr ^-1 or less, but surprisingly, sufficient deodorization can be achieved even when the air supply is increased.

This is based on the finding that the deodorizing function of odor-decomposing bacteria, especially MM-decomposing bacteria and DMS-degrading bacteria, depends on the amount of cells, and actively increases the air supply amount, that is, increases the SV. This is because the operation can maintain a high amount of bacterial cells.

 Hereinafter, the present invention will be described in detail with reference to the drawings.

As a biological deodorizing apparatus capable of stably and efficiently processing odor gas containing a sulfur-based odor substance at low cost, the present applicant has previously provided a processing tower having a malodor gas supply pipe at the bottom, A packed layer provided with three or more stages separated vertically in the tower, carrying microorganisms that decompose malodorous components, and through which malodorous gas to be treated is passed in an upward flow; Sprinkling pipes for spraying washing water on the upper side, between the upper and lower packed beds, and above the watering pipes for the lower packed bed, through which the flow of the odorous gas passes, but from the top down A biological plate deodorizing device comprising a partition plate for preventing water flow to the drain plate, and a drain pipe for discharging water accumulated on the partition plate to the outside of the tower, wherein the packed bed is provided for removing malodorous gas supplied into the processing tower. Forming an H ₂ S decomposition layer, a MM decomposition layer, and a DMS decomposition layer in order from the upstream side We applied for a patent for a biological deodorizer (Japanese Patent Application No. 63-71642, hereinafter referred to as "first application").

When the present invention is applied to the above-mentioned prior application, extremely excellent effects can be obtained.

FIG. 1 is a schematic sectional view showing an example in which the method of the present invention is applied to the biological deodorizing apparatus of the prior application.

The biological deodorizing apparatus of this embodiment has an odor gas supply pipe at the bottom.
11 and a processing tower 13 having a processing gas discharge pipe 12 at the top.
Inside, filling tanks 14, 15, 16 are provided in three stages separated vertically, H ₂ S decomposition layer 14, MM decomposition layer 15 and DMS
A decomposition layer 16 is set.

That is, a grit (lattice) (not shown) is provided in the tower 13 in three stages, and a ventilation and water-permeable supporting member (not shown) such as a perforated plate or a mesh sheet is placed thereon. Further, the packed layers 14, 15, 16 are supported thereon by peat. Activated sludge is carried on the packed bed (H ₂ S decomposition layer) 14, and activated sludge or DMSO culture bacteria is carried on the packed bed (MM decomposition layer) 15 of these packed beds 14, 15 and 16. . The packed bed (DM
Activated sludge or DMSO culture bacteria are also supported on the S decomposition layer 16. DMSO cultures are preferred because the acclimatization period is shorter.

17, 18 and 19 are sprinkler pipes for spraying the washing water on each of the packed beds 14, 15 and 16, and each sprinkler pipe 17, 18 and 19 has a pump.
P _1, P _2, P ₃ washing water storage tank 23 from the pipe 20, 21, 22 with a (water, alkali solution, buffer solution or the like) is supplied.

Thus, pH sensors 24, 25, and 26 are inserted and provided near the bottom of each of the packed layers 14, 15, and 16. Pumps P ₁ , P ₂ , and P ₃ are respectively operated by control devices (not shown). Each pH
Based on the detection values of sensors 24, 25, 26, watering pipes 17, 18,
The watering amount and the watering frequency of 19 are configured to be controlled.

In order to perform the odor gas deodorizing treatment by such a biological deodorizing apparatus, first, the odor gas is supplied from the air supply pipe 11 to the treatment tower 13.
To be introduced. Odor gas is treated by activated sludge in the process of passing through the packed bed (H ₂ S decomposition layer) 14 and contains H ₂ S
Is oxidatively decomposed. Next, in the process of passing through the packed bed (MM decomposition layer) 15, the sludge is treated with activated sludge or DMSO culture bacteria, and the contained MM is oxidatively decomposed. In addition, the packed bed (DM
DMS still contained in the process of passing through the (S decomposition layer) 16 is DMSO
Degraded oxidatively by culture. Also, if there is methyl disulfide in the odor gas, it is also oxidatively decomposed in the DMS decomposition layer.

The gas thus deodorized is discharged from the discharge pipe 12 at the top of the tower.

Note that sulfur-based odor components such as H ₂ S, MM, and DMS are oxidatively decomposed to sulfate ions by the respective decomposing bacteria.

Therefore, the odorous components are oxidatively decomposed and deodorized in the packed layers 14 to 16, and a sulfate ion having substantially the same amount as that of the removed sulfur-based substance is generated and gradually accumulated when left as it is. Since this sulfate ion inhibits the biological reaction of microorganisms, the packed bed 14-16
It is necessary to sprinkle the washing water from the sprinkling pipes 17 to 19 to wash the sulfate ions out of the tower. It is also necessary to replenish water to maintain the activity of the microorganism.

In the apparatus of this embodiment, in such a biodegradation process, each of the pump P ₁ to P ₃ in the case where the detection value of the pH sensor 24 to 26 of each filling layer 14 to 16 is out of the following preferred ranges Operate to wash each packed bed 14-16 and maintain the pH of each in a suitable range.

Water is usually used for washing, but when the load is high and the amount of produced sulfuric acid is large, washing is appropriately performed using an alkaline solution or a buffer solution to improve the efficiency of pH adjustment.

Thereby, each of the filling tanks 14 to 16 is suitable for each decomposing bacterium.
Since the pH is maintained, an environment for improving the growth and decomposition activity of each decomposing bacterium is prepared. Under such an environment, the amount of MM-degrading bacteria and DMS-degrading bacteria can be maintained in accordance with the supply amount of the odor gas, that is, the load. For this reason, in the present invention, it is preferable to make the supply amount of the odor gas larger than that of the conventional method. Air supply volume is usually space velocity (SV, unit: hr ^-1 )
In the present invention, the MM decomposition layer or
For each volume of the DMS decomposition layer, the human odor is SV300
~3000hr ^-1, preferably 600~3000hr ^-1, it is preferable to supply air at a high SV that SV200hr ^-1 or more to the treatment tower. With such a high SV, MM degrading bacteria and DM
Since S-decomposing bacteria proliferate and can be maintained at a high bacterial concentration, the degrading activity is improved, and a high-load treatment impossible by the conventional method is possible. Note that the H ₂ S decomposition layer, the MM decomposition layer, and the DMS decomposition layer may be formed in multiple stages in one column, or may be formed as separate independent columns.

The method shown in FIG. 1 is very advantageous because a suitable pH condition can be set for each packed bed.

In the present invention, among the carriers (peats) of the packed bed supporting each degrading bacterium, it is preferable that the pH of the carrier supporting DMS and MM degrading bacteria is adjusted to about 7.0 before use.

Further, according to the method of the present invention, as described above, it is possible to treat human odor at a high load of SV200 hr- ¹ or more for treatment or the like, and SV600 hr- ¹ or more for a MM decomposition layer or a DMS decomposition layer. However, if the load is excessively high, long-term stability may be impaired. For this reason, in the present invention, it is preferable to treat the MM decomposition layer or the DMS decomposition layer at SV 3000 hr ⁻¹ or less.

In the example shown in FIG. 1, the method of directly measuring the pH of the packed bed and controlling water sprinkling based on the results is shown. However, the method of the present invention detects the MM and DMS concentrations of the odor gas to be treated. , MM and DMS The amount of sulfuric acid generated from the load of MM and DMS on the packed bed is calculated, and based on the calculated value, an alkaline solution or a buffer solution for neutralizing the generated sulfuric acid is sprayed.

Spray sufficient washing water or weak alkaline solution to wash and remove the generated sulfuric acid.

Such a method can be easily implemented.

[Action] In the odor gas biological deodorizer, as described above, H ₂
An S-decomposed layer, an MM-decomposed layer, and a DMS-decomposed layer are formed. The pH suitable for each decomposing bacterium is H2S decomposing bacterium, pH _{2 to} 4, MM decomposing bacterium and DM
S-degrading bacteria have a pH of 6-8.

Therefore, in the conventional method of controlling watering from the pH of the washing wastewater at the lower part of the apparatus, there is a possibility that the pH may be increased to a relatively low H ₂ S decomposition layer, which is suitable for H ₂ S decomposing bacteria. Environment cannot be set, and the amount of washing water to be used becomes excessively large.

When the odor gas is processed by passing through the H ₂ S decomposition layer, the MM decomposition layer, and the DMS decomposition layer in the order of upward flow, the amount of water sprayed from the upper side and the frequency of water spray are at least that of the MM decomposition layer and the DMS decomposition layer. It is sufficient to maintain the pH 6 to 8 and the H ₂ S decomposition layer at pH ₂ to 4, respectively. Thus, by supplying the necessary washing water only to the necessary places, the washing water amount and washing cost can be reduced. I can do it.

As described above, according to the present invention, it is possible to set a suitable pH for each decomposing bacterium in each decomposing layer, so that the growth of each decomposing bacterium, the decomposing activity is improved, and a high load treatment becomes possible. The deodorizing efficiency is greatly improved.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Example 1 According to the present invention, deodorizing treatment of human urine odorous gas having the composition shown in Table 1 was performed by the apparatus shown in FIG. 1 under the load shown in Table 1.

The spraying of the washing water from the sprinkling pipes 17 to 19 was controlled so that the detection values of the pH sensors 24 to 26 were in the following ranges.

pH sensor 24 (pH of H ₂ S decomposition layer): 2.0 to 4.0 pH sensor 25 (pH of MM decomposition layer): 6.8 to 7.5 pH sensor 26 (pH of DMS decomposition layer): 6.8 to 7.5 The results are shown in Table 1.

Comparative Examples 1 and 2 In the same manner as in Example 1, except that the washing water was sprayed only from the top watering pipe so that the pH of the washing wastewater at the bottom of the tower was 2.0, and the load shown in Table 1 was used. Deodorizing treatment.

 Table 1 shows the composition of the processing gas.

From Table 1, it is clear that the method of the present invention can perform advanced deodorizing treatment by high load treatment.

[Effects of the Invention] As described in detail above, according to the biological deodorizing method of the present invention,
By stably maintaining the segregation of the decomposing bacteria of each odor component and maintaining a suitable pH range for each decomposing bacteria, the growth and decomposition activity of each decomposing bacteria can be improved. For this reason, high load processing is possible. In addition, the amount of washing water can be controlled to the minimum necessary, and it is possible to reduce washing water costs and watering costs.

Therefore, according to the method of the present invention, an efficient deodorizing treatment can be performed at low cost.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a biological deodorizing apparatus suitable for carrying out the present invention. 11 ... air supply pipe, 12 ... discharge pipe, 13 ... treatment tower, 14 ... packed bed (H ₂ S decomposition layer), 15 ... packed bed (MM decomposition layer), 16 ... packed bed (DMS decomposition) Layers), 24,25,26 …… pH sensors 17,18,19 …… sprinkler pipes.

Claims (1)

(57) [Claims] 1. A packing layer for hydrogen sulfide decomposition carrying microorganisms for decomposing hydrogen sulfide, a packing layer for decomposing methyl mercaptan carrying microorganisms for decomposing methyl mercaptan, and a microorganism for decomposing methyl sulfide in order. In the method for deodorizing by flowing the supported bed for decomposition of methyl sulfide in an upward flow, the pH of the bed for decomposition of methyl mercaptan and the bed for decomposition of methyl sulfide are maintained at 6 to 8, and the hydrogen sulfide is maintained. A biological deodorization method comprising maintaining the pH of a packed bed for decomposition at 2 to 4.