JP3199992B2 - Biological deodorization method for hydrocarbon odorous substances - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for biological deodorization of a malodorous component, and in particular, removes microorganisms adhering to a packed bed when deodorizing a malodorous gas containing a hydrocarbon-based odorous component using a filler. About the method.

[0002]

2. Description of the Related Art When a biological substance is deodorized for a long period of time to remove hydrocarbon-based odorous substances such as benzene and toluene from a gas containing hydrocarbon-based odorous substances such as benzene and toluene, microorganisms adhering to the filler are removed. Proliferation increases the pressure drop in the packed bed significantly. Further, since the inside of the packed layer is partially or entirely closed, the deodorizing function is significantly reduced.
Conventionally, in such a case, a method has been adopted in which the filler is taken out of the system, and the adhered microorganisms are mechanically peeled off by washing with water or a chemical solution is washed with sodium hypochlorite. However, in the former method of removing adhered microorganisms, there is a problem in workability, in the latter method, the effect on the adhered microorganisms by the hypochlorite bactericidal action is large, and the deodorizing performance at the time of restarting operation is reduced, Again, there is a problem that it takes a long time to adapt the microorganisms to the inflowing odor component.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above problems and efficiently removes and removes microorganisms adhering to a packed bed against a malodorous gas containing a hydrocarbon odorous substance.
An object of the present invention is to provide a deodorizing method capable of preventing an increase in pressure loss of a packed bed due to growth of microorganisms and maintaining deodorizing performance.

[0004]

In order to solve the above-mentioned problems, the present invention provides a method for deodorizing a hydrocarbon-based odor by passing a malodorous gas through a filler on which a biofilm is formed. Excessive microorganisms are brought into contact with water containing hydrogen peroxide to exfoliate and remove the microorganisms, thereby preventing an increase in pressure loss. In the above method, the contact with water containing hydrogen peroxide is preferably performed after bringing the packed bed into contact with an alkali agent or catalase as a catalyst for hydrogen peroxide.

[0005] In the present invention, hydrocarbon-based odorants are more specifically aliphatic hydrocarbons, lower fatty acid / ether-based hydrocarbons, ketone-based hydrocarbons, alcohols and the like. The functions of hydrogen peroxide include oxidation of the biofilm, separation of the biofilm due to foaming in the gap between the membranes and the gap between the membrane substrates, separation by physical vibration, and adsorption and floating of the biofilm to the generated bubbles. This is to remove the resulting excess biofilm. As described above, in the present invention, in a packed bed filled with a filler to which microorganisms are attached, when the pressure loss in the packed bed is increased, the biodegradation is possible as an oxidizing agent while the filler is filled. By using an aqueous hydrogen oxide solution and using an alkaline agent such as sodium hydroxide or a catalase enzyme as a catalyst for the oxidation reaction of hydrogen peroxide, the attached microorganisms are separated.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, specifically, a hydrogen peroxide solution as an oxidizing agent is injected into water circulating in a biological deodorizing apparatus (hereinafter referred to as circulating water) to fill the circulating water. Hydrogen peroxide is supplied to the layer, and the microorganisms attached to the filler are decomposed by the oxidizing power and the foaming effect of oxygen gas generated at the time of decomposition thereof, or the attached microorganisms are peeled off from the filler. Next, a case where a catalyst is used in combination as a pre-process will be described. Catalysts for hydrogen peroxide include alkaline agents and catalase. Alkali agents are sodium hydroxide, potassium hydroxide and calcium hydroxide.

[0007] Sodium hydroxide or catalase enzyme is injected to allow the sodium hydroxide or catalase enzyme to sufficiently penetrate the deposits. After the permeation, the circulating water containing these catalysts is discharged, and then the circulating water into which the hydrogen peroxide solution as the oxidizing agent has been injected is circulated. In the packed bed, the microorganisms adhering to the filler are decomposed by the oxidizing power of hydrogen peroxide and the foaming effect of oxygen gas generated at the time of decomposition thereof, and the adhered microorganisms are peeled off from the filler. The catalyst immersion step is intended to promote the generation of oxygen gas due to the decomposition of hydrogen peroxide in the deposits on the filler, and particularly to enhance the effect of peeling by foaming.

Next, the exfoliation of microorganisms from the packed bed of the present invention will be described in detail. While circulating the circulating water of the deodorization tower, adjust the hydrogen peroxide injection pump so that the concentration of hydrogen peroxide is 1% by weight or less (hereinafter referred to as 1%) in the circulating water and inject the hydrogen peroxide water. Then, the circulating water containing hydrogen peroxide is brought into contact with the filler for about 15 minutes. Due to the oxidizing power of hydrogen peroxide itself and the foaming caused by decomposition, the microorganisms separated from the filler become fine particles and migrate into the circulating water. The exfoliated microorganisms formed into SS in the circulating water are discharged out of the system together with the circulating water in the circulating water tank.

When sodium hydroxide is used as a catalyst, sodium hydroxide is injected into the circulating water while circulating in the circulating water of the biological deodorizer. The pump is adjusted so that the concentration of sodium hydroxide in the circulating water is 3% or less, and the circulating water is brought into contact with the filler for about 15 minutes. Next, the circulating water is discharged. After that, make-up water such as industrial water is injected into the circulating water tank, and the hydrogen peroxide concentration becomes 1%.
Adjust the hydrogen peroxide injection pump so that
The circulating water is brought into contact with the filler for about 15 minutes. The same procedure is used when a catalase enzyme is used as a catalyst instead of sodium hydroxide. At this time, the catalase enzyme concentration in the circulating water is 10% or less.

[0010] The cause of the increase in the pressure loss of the filler is that the heterotrophic bacteria assimilate hydrocarbon-based odor substances and the like in the inflowing gas, and the bacteria grow. This heterotrophic bacterium has a large amount of cell growth per substrate and, in addition, produces a highly viscous extracellular polymer. Conventionally, a chemical containing hydrogen peroxide as a main component has been used for removing biological slime, but a method for removing adhered microorganisms using hydrogen peroxide to eliminate pressure loss of a biological deodorizing device is still proposed. It has not been. In order to continue the deodorizing treatment again after the stripping operation, it is effective to use biodegradable hydrogen peroxide.

Next, the action of sodium hydroxide and a catalase enzyme used as a catalyst will be described. Generally, alkali has the effect of dissolving microorganisms. As a pre-process,
By washing with an aqueous solution of sodium hydroxide, the attached matter is partially dissolved and peeled off. After the washing is completed, the aqueous solution of sodium hydroxide is discharged, and further washed with a hydrogen peroxide solution. Hydrogen peroxide water decomposes and separates deposits due to its oxidizing power, and at the same time, reacts with sodium hydroxide that has penetrated the attached microorganisms in the attached microorganisms in the attached microorganisms, decomposing hydrogen peroxide and exhausting oxygen gas violently. . The foaming due to the generation of oxygen gas promotes the detachment of the deposit.

As described above, the pre-cleaning step using sodium hydroxide has the effect of promoting the decomposition of hydrogen peroxide that has come into contact with the deposits as a catalyst and at the same time enhancing the cleaning effect, as well as the effect of dissolving and removing sodium hydroxide itself. is there. In the pre-cleaning step with the catalase enzyme, the catalase enzyme itself does not have the property of decomposing microorganisms, so it is not expected that the adherents are peeled off.However, like the sodium hydroxide, it promotes the decomposition of hydrogen peroxide and generates oxygen gas. . Therefore, the same effect as when sodium hydroxide is used is obtained. Catalase enzyme is a substance originally possessed by aerobic microorganisms, and is advantageous in that the effect on microorganisms is extremely small as compared with sodium hydroxide.

Next, the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic sectional view of an apparatus used in the present method. In FIG. 1, a deodorization tower 3 is provided with a packed bed 2 filled with a filler and a sprinkling section 4 for spraying circulating water to the packed bed above the packed bed 2, and a circulating water layer 8 below the packed bed. Provided. The circulating water is circulated from the circulating water tank 8 to the sprinkling section 4 via the pump 6. After closing the damper of the raw gas inflow pipe 1, the circulation pump 6 is turned on at 30 l / m.
While operating at “in”, the hydrogen peroxide water injection pump 12 is used to inject hydrogen peroxide in the circulating water so that the concentration becomes 1%. When the concentration of hydrogen peroxide in the circulating water reaches about 1%,
Decomposition and detachment of attached microorganisms occur, which causes SS in circulating water
Increase.

When the SS of the circulating water reaches 50 mg / liter, the drain valve 7 is opened to discharge the circulating water. After the discharge, 1 liter of make-up water is injected and circulated in the tower to wash away residual hydrogen peroxide water. After repeating injection, circulation and discharge of make-up water, the operation returns to the regular deodorizing operation. Next, the case of using a catalyst will be described. 30 liters of circulation pump 6
The sodium hydroxide (catalase enzyme) injection pump 13 is used to inject sodium hydroxide in the circulating water to 3% (10% for catalase enzyme) while operating at min. After continuing the circulation for about 15 minutes, the drain valve 7 is opened to discharge the aqueous sodium hydroxide solution (or the aqueous catalase enzyme solution).

With the drain valve 7 closed again, while operating the circulation pump 6 at 30 liter / min, the hydrogen peroxide concentration in the circulating water is reduced to 1% by using the hydrogen peroxide water injection pump 12.
Inject so that it becomes. Hydrogen peroxide concentration in circulating water is 1
%, The adhered microorganisms are decomposed and separated, and the SS of the circulating water increases. 50mg of circulating water SS
/ Liter, the drain valve 7 is opened to discharge the circulating water. After the discharge, make-up water 10 is injected and circulated in the tower to wash away residual hydrogen peroxide water. After repeating injection, circulation and discharge of make-up water, the operation returns to the regular deodorizing operation.

[0016]

The present invention will be described below in more detail with reference to examples. Example 1 A biological deodorization experiment was conducted for about one month using the experimental apparatus of FIG. Inject the reagents of benzene and toluene, which are volatile organic compounds, into the air and adjust the concentration of benzene and toluene to 2
What was adjusted to be 0 to 50 ppm was used as a raw gas. The conditions of the deodorization experiment are as follows. LV: 0.2 m / sec, circulating water sprinkling speed: 30 liter / min, raw gas temperature: 30 ° C. Filling material: Terralet (registered trademark, manufactured by Nippon Steel Chemical Machine Co., Ltd.) Filling layer height: 1 m

Under these conditions, biological deodorization was carried out, and an experiment of detachment of microorganisms adhering to the packed bed was carried out in a state where the pressure loss per 1 m height of the packed bed was raised to 50 mmH ₂ O. The experimental apparatus was operated in the same deodorization experiment, and hydrogen peroxide was injected into the circulating water so that the concentration became 1%. The circulating water SS at this time was 3 mg / liter. Immediately after the injection, foaming occurs from the attached matter, decomposition and detachment of the attached matter begin to occur,
The circulating water SS increased to 30 mg / liter. Thirty minutes after the start of the injection, the circulating water was discharged from the circulating water tank because the SS concentration of the circulating water became approximately 60 mg / liter, and fresh makeup water was injected. After that, the residual hydrogen peroxide was washed once by discharging and injecting the circulating water, and then returned to the regular deodorization experiment. The SS in the circulating water at this time was 3 mg /
Pressure loss per liter, packed bed height 1m is 10mm
H ₂ O was obtained.

Example 2 A case where a catalyst is used in combination will be described. The experimental apparatus was operated in the same deodorization experiment, and pre-process washing was performed with an aqueous sodium hydroxide solution. After washing for 15 minutes, SS in circulating water is 15mg
/ Liter. After discharging the aqueous solution of sodium hydroxide, an aqueous solution of hydrogen peroxide was injected into the circulating water to a concentration of 1%. The circulating water SS at this time was 3 mg / liter. Immediately after injection, foam is generated from the deposit,
Separation began to occur and the circulating water SS increased to 50 mg / liter. 15 minutes after the start of the injection, the circulating water was discharged from the circulating water tank because the SS concentration of the circulating water became approximately 100 mg / liter, and fresh makeup water was injected. After this,
After the residual hydrogen peroxide was washed once by discharging and injecting circulating water, the operation was returned to the regular deodorization experiment. The SS in the circulating water at this time was 3 mg / liter, and the pressure loss per 1 m of the packed bed was 5 mmH ₂ O.

Example 3 A case where a catalase enzyme was used instead of sodium hydroxide as the pre-step washing in Example 2 is described below. Perform biological deodorization deodorization experiment under the same conditions as in Example 2, in a state of increasing the pressure loss per packed bed height 1m to 50 mm H ₂ O, an experiment was performed adhering microorganisms peeling of the filling layer. The experimental apparatus was operated in the same deodorization experiment, and the catalase enzyme was injected into the circulating water so as to be 10%. The circulating water S at this time
S was 3 mg / liter. Circulation was performed for 15 minutes after injection, but there was no change in SS concentration in the circulating water. After discharging the catalase enzyme aqueous solution, 1% of hydrogen peroxide solution was injected into the circulating water. Immediately after injection, foam is generated from the deposit,
Decomposition and delamination of deposits begin to occur, and the circulating water
mg / liter. 15 minutes after the start of infusion,
When the SS concentration of the circulating water became about 80 mg / liter, the circulating water was discharged from the circulating water tank, and fresh makeup water was injected. After that, the residual hydrogen peroxide was washed once by discharging and injecting the circulating water, and then returned to the regular deodorization experiment.
The SS in the circulating water at this time was 3 mg / liter, and the packed bed 1
The pressure loss per m was 8 mmH ₂ O.

Comparative Example 1 When deodorizing treatment was carried out for one month under the same conditions as in Example 1, the pressure loss per 1 m of the packed bed became 50 mmH ₂ O, so that the microorganisms were removed. After closing the damper of the raw gas inflow pipe, sodium hypochlorite was injected into the circulating water so that the effective chlorine concentration became 3%. By operating the circulation pump, circulating water containing sodium hypochlorite was sprinkled on the packed bed at 30 L / min for 60 minutes.
After discharging the circulating water in the circulating water tank, make-up water was injected to wash residual sodium hypochlorite with water. As a result, under the same experimental conditions, the pressure loss per 1 m of the packed bed was 10 mmH ₂
It recovered to O.

Table 1 shows Examples 1 to 3 (invention) and Comparative Example 1.
A comparison of the pressure loss, the time required for cleaning, and the benzene removal performance after cleaning is shown for (conventional method). According to the method of the present invention, the same pressure loss can be eliminated in about half the cleaning time of the conventional method, the benzene removal performance after the removal is excellent, and the removal rate immediately after the cleaning is more than three times that of the conventional method. Was less than 1/5.

[0022]

[Table 1] 1) () Inner water washing time 2) Time until removal rate reaches 90%

[0023]

The effects of the present invention are as follows. (1) Adhering microorganisms can be easily removed in a short time by a very simple method. (2) The degree of deterioration in deodorizing performance after peeling is small. (3) The time required for restoring the deodorizing performance after detachment of the adhered microorganisms (reestablishment) is relatively short.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an apparatus used in the method of the present invention.

[Explanation of symbols]

1: raw gas, 2: packed bed, 3: deodorization tower, 4: sprinkling unit,
5: Gas outlet, 6: Circulating water pump, 7: Drainage, 8:
Circulating water tank, 9: NaOH (catalase enzyme) injection line, 10: H ₂ O ₂ injection line, 11: makeup water, 12:
H ₂ O ₂ injection pump, 13: NaOH (catalase enzyme) injection pump, 14: NaOH (catalase enzyme) storage tank, 15: H ₂ O ₂ storage tank

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) B01D 53/38 B01D 53/34 ZAB C12N 1/00

Claims (2)

(57) [Claims] 1. A method for deodorizing a hydrocarbon-based odor by passing a malodorous gas through a filler on which a biofilm is formed, wherein excessive microorganisms adhering to the filler are peeled off by contact with water containing hydrogen peroxide. A biological deodorizing method characterized by removing and preventing an increase in pressure loss. 2. The biological deodorization method according to claim 1, wherein the contact with the water containing hydrogen peroxide is performed after bringing the packed bed into contact with an alkali agent or catalase as a catalyst for hydrogen peroxide.