JP2003290621A - Two-stage removal method for malodorous substance generated from composting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for perfectly deodorizing the offensive smell of the exhaust gas from a composting apparatus. <P>SOLUTION: In a method for removing a malodorous substance generated from the composting apparatus, a device packed with a deodorant based on a copper compound, a manganese compound and clay or activated carbon is used in a first stage to treat the malodorous substance and the exhaust gas issuing from the first stage is passed through the upper part of a hydrogen peroxide aqueous solution provided in a second stage or treated using a device packed with a catalyst carrying a noble metal. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composting facility for reusing food waste related to food discarded at home, restaurants, etc. as fertilizer, and removes offensive odor substances generated by rotting of food waste. Regarding technology.

[0002]

2. Description of the Related Art Conventionally, in a composting facility, an adsorbent such as activated carbon or zeolite has been used as a deodorant for removing a malodor generated from raw garbage. The mechanism for removing these malodors is mainly what is generally called physical adsorption, and takes in the malodorous substance into the pores of the adsorbent.

Therefore, when the malodorous substance accumulated in the adsorbent reaches saturation, breakthrough of the malodorous substance starts, and it is necessary to regenerate the adsorbent by heating. However, during this regeneration, the malodorous substance will be released as it is,
In practice, it is customary to incinerate and discard it without regenerating it.

The frequency of exchanging the adsorbent such as activated carbon in the composting facility varies depending on the change in the components of the garbage itself, the amount of the adsorbent used, and the deodorizing facility, but a bad smell leaks in about one week to two months. However, the number of days cannot be limited, but it is changed to about 3 months, but the limit is about 3 months.

[0005]

DISCLOSURE OF THE INVENTION The present invention is characterized by prolonging the use time of a remover (adsorbent) used for removing a malodorous substance generated from a composting device. Its purpose is to provide a method of significantly reducing the replacement frequency.

Further, the present invention provides an adsorbent that prevents deterioration of the deodorant due to mist, preferably by heating, in the deodorizing equipment of the composting device, and does not desorb the malodorous substance due to the heating. The purpose of the present invention is to provide a method for significantly reducing the frequency of agent replacement by using it as a deodorant.

Furthermore, the present invention is directed to complete deodorization by decomposing and removing a new chemical substance when a malodorous substance acts as a deodorant in the deodorizing equipment of a composting device to generate a new chemical substance. Has an aim.

[0008]

In order to solve the above-mentioned problems, the present inventors have investigated whether the life of deodorizing performance of activated carbon, which is an adsorbent mainly used in the past, can be extended. investigated. Then, when the activated carbon filling container of the deodorizing equipment of the composting device used for one month was confirmed, wetting of the activated carbon filled with water vapor due to dew condensation was observed in about 80% of the whole.

That is, it was found that the cause of the deodorizing ability reduction was poisoning of the adsorbent in the deodorizing equipment by the mist generated in the composting device, apart from the limit of the adsorbing ability of the activated carbon. I tried to prevent condensation by heating the deodorizing equipment. When the container filled with activated carbon was heated (50 to 100 ° C) and the compost exhaust gas was ventilated, it was not so different from normal temperature (when not heated) at 50 ° C, but at 70 ° C or higher, It was confirmed that odor leaked from the outlet. We have
As a result, it was determined that it is difficult to significantly reduce the replacement frequency, which is the object of the present invention, by removing the malodorous substance by physical adsorption such as activated carbon, and the adsorbent used is a strong chemical adsorbent or stably immobilized. The method for removing the malodorous substance by using a reactive adsorbent that is converted into a possible substance or an odorless substance and immobilized is investigated. As a result, under certain temperature conditions,
It was found that the frequency of replacement of the deodorant can be significantly reduced by bringing the exhaust gas from the composting device into contact with a deodorant containing manganese oxide and copper oxide and having a specific composition.

That is, the inventors of the present invention added a clay compound or activated carbon to a deodorant composed of manganese oxide and copper oxide, whereby under high humidity conditions,
A method for removing malodorous substances from raw garbage characterized by maintaining the ability to remove malodorous substances, suppressing the desorption reaction of adsorbed malodorous substances at high temperature, and prolonging the retention time of the malodorous substance removing action. It was provided in Japanese Patent Application No. 2001-316872.

That is, in the malodorous substance removing method of the present invention, the first stage deodorant specified by the matters described in the following (1) to (4) disclosed in Japanese Patent Application No. 2001-316872 is used. . (1) In a method for removing a malodorous substance in a gas discharged from a composting device, a manganese oxide and a copper oxide are contained in a weight ratio of 9: 1 to 4: 6, and further in a clay compound or activated carbon. A method of removing a malodorous substance, characterized in that a mixture containing 10 to 90% by weight based on the total weight of the deodorant is used as the deodorant, wherein the clay compound is acid-treated. A method for removing a malodorous substance according to (1) above, which is activated clay.
(3) The method for removing a malodorous substance according to (1) or (2) above, which contains at least one selected from the above clay compounds or activated carbon in an amount of 20 to 70% by weight based on the total weight of the deodorant. 4) A method for removing a malodorous substance according to any one of the above (1) to (3), which comprises heating the exhaust gas to 30 to 120 ° C. and then contacting it with a deodorant.

However, when the amount of alcohols and seasonings in the garbage increases, an aromatic odor, rarely an ammonia odor, may be felt at the outlet of the device using the first-stage deodorant. I understood. It is considered that the cause of these odors was changed by the reaction of the malodorous substance with the first-stage deodorant. Since the type and amount of these chemical substances always change depending on the situation of the input garbage, it cannot be qualitatively or quantitatively determined, but from the results confirmed using a gas detector tube, the chemical substance is trimethylamine. , Triethylamine, isobutyric acid, ethyl acetate, etc. were confirmed to be the main.

The inventors of the present invention led the exhaust gas from the first stage to the upper portion of diluted hydrogen peroxide solution (hydrogen peroxide aqueous solution) and used this aqueous solution as a deodorant to obtain the above chemical composition. It was found that the substance can be oxidatively decomposed and completely deodorized. In terms of equipment, an airtight container with an entrance and exit as shown in Fig. 1 should be filled with about half of the hydrogen peroxide solution, and the exhaust gas from the first stage should pass through the upper part of the container, and the vapor pressure Hydrogen oxide oxidizes the chemical substances in the exhaust gas. The inventors further connected a device filled with a catalyst supporting a noble metal (preferably a honeycomb catalyst) as shown in FIG. 2 in the subsequent stage of the first-stage device to decompose the above chemical substances and eliminate odor. I found that it can be converted. That is, the present invention is specified by the matters described in [1] to [6] below. [1] In a method for removing a malodorous substance generated from a composting device, the treatment is carried out using a device filled with a deodorant mainly containing a copper compound and a manganese compound and clay or activated carbon in the first step, and the first step The effluent gas discharged is passed through the upper part of the hydrogen peroxide aqueous solution provided in the second stage, or is treated by using a device filled with a catalyst supporting a noble metal. Removal method, [2]
Method for removing malodorous substance according to [1], wherein the concentration of the aqueous hydrogen peroxide solution is 1 to 35% [3] Malodorous substance according to [1], wherein the second-stage catalyst is honeycomb-shaped [4] The noble metal is Pt, Pd and / or A
u, the method for removing a malodorous substance according to [1] or [3], [5] the amount of the noble metal supported on the honeycomb-shaped catalyst is 1 g / L to 20 g / L on a honeycomb volume basis,
The method for removing a malodorous substance according to [3] above, [6] the method according to any one of [1] to [5] above, wherein the temperature of the exhaust gas from the composting device is 20-15.
A method for removing malodorous substances in the range of 0 ° C.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The gas discharged from a compost contains a large amount of water vapor generated from food waste. In order to prevent this water vapor from condensing on the surface of the deodorizing agent of the deodorizing equipment, the temperature of the exhaust gas from the composting device should be 20 ° C.
It is preferable to keep the above. Although the upper limit of the temperature is not particularly limited, it has been found that the odorous component does not break through up to 150 ° C in the present invention. Therefore, the temperature of the exhaust gas from the composting device is preferably in the range of 20 to 150 ° C. In the present invention, the copper compound used in the first stage is preferably an oxide, and CuO is particularly preferable, but cuprous oxide, basic copper carbonate, and copper hydroxide may be contained.

In the present invention, the manganese compound used in the first step is preferably an oxide, especially MnO ₂
However, MnO, Mn ₂ O ₃ , Mn ₃ O _{4 and the} like may be contained. The specific surface area of the manganese oxide is not particularly limited, but in general, the higher the specific surface area, the more preferable it is, preferably 100 m ² / g or more, more preferably 200 m ² / g or more.

The copper compound and the manganese compound may be mixed by either physical mixing or coprecipitation. Examples of the physical mixing method include dry physical mixing in which respective compounds are mixed, and wet kneading in which a slurry of each component or its precursor is mixed, but any method may be used.

The mixing ratio of the copper oxide and the manganese oxide is preferably in the range of 1: 9 to 4: 6 by weight, more preferably 2: 8 to 4: 6.

The weight ratio of copper oxide to manganese oxide is 1:
If it is outside the range of 9 to 4: 6, the performance of removing the malodorous substance is deteriorated, which is not preferable.

In the present invention, the amount of clay or activated carbon used in the first step is 10 based on the total weight of the first step deodorant.
It is preferably about 90% by weight. If this ratio is lower than 10% by weight, the malodorous substance itself in the exhaust gas from the composting device or another malodorous substance changed from it will start to break through in a short life, which is not preferable. On the other hand, if it exceeds 90% by weight, the malodorous substance itself in the exhaust gas from the composting device starts to break through quickly, which is not preferable. As the clay, those having high water retention and water absorption and acid properties are preferable, and examples thereof include commercially available activated clay and montmorillonite. Clay or activated carbon may be added alone or in a mixture.

In the present invention, the shape of the deodorant used in the first step can be various shapes such as pellet shape, sheet shape and honeycomb shape. A molded body is obtained by mixing the components constituting the deodorant or their precursors, molding, drying, and, if necessary, firing. Further, each component may be attached to a honeycomb or the like.

In the present invention, the concentration of the hydrogen peroxide aqueous solution used in the second stage can be 1 to 35%, but it is preferably about 2 to 10% from the viewpoint of easy handling.

In the present invention, the catalyst used in the second stage is preferably honeycomb-shaped, and the noble metal supported on the catalyst is preferably Pt, Pd and / or Au. The amount of the noble metal supported on the honeycomb catalyst is preferably 1 g / L to 20 g / L in the honeycomb capacity base. It is preferable that the material of the honeycomb is cordierite, and the surface of the honeycomb is coated with silica and alumina by 1 to 10% by weight.

In order to maintain the performance of the noble metal-supported honeycomb catalyst, it is important not to coat the noble metal surface with steam mist or the like. As a method for this, it is effective to provide a drain trap at the catalyst inlet to reduce the humidity in the catalyst section or to heat the exhaust gas from the first stage. The heating is effective at 50 ° C to 200 ° C, more preferably 70 ° C.
C. to 100.degree. C. is desirable.

[0024]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

(Example 1) As the first-stage deodorant, a deodorant molded into a pellet of 1.6 mm in diameter containing manganese dioxide, copper oxide and activated clay in a ratio of 40:10:50 was used. 10ml was filled in the reaction tube of
The test was performed three times using a 2% aqueous hydrogen peroxide solution in the second stage. The first test was at a temperature of 50 ° C and a gas flow rate of 25.
The second test passed the exhaust gas from the composting device at a temperature of 90 ° C. and a gas flow rate of 25 liters / min at the gas flow rate of 25 liters / min. Then, the odor at the outlet of the reaction tube was judged by a sensory test. The results are shown in Table 1.

(Second Embodiment) The first stage is the condition of the first embodiment.
A deodorizing performance test was conducted under the conditions of Example 1 using a honeycomb catalyst supporting 1% of platinum and 1% of palladium in the second stage. The results are shown in Table 1.

(Embodiment 3) The first stage is the condition of Embodiment 1,
In the second stage, a honeycomb catalyst supporting 1% of gold was used and a deodorizing performance test was conducted under the conditions of Example 1. The results are shown in Table 1.
Shown in.

Comparative Example 1 A deodorizing performance test was carried out under the conditions of Example 1 using the deodorizing agent of the first stage of Example 1 only. The results are shown in Table 1. Test results

[0029]

[Table 1]

[0030]

According to the present invention, the odor of exhaust gas from the composting device can be completely eliminated.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a mode in which the exhaust gas discharged from the first stage is passed through an upper portion of an aqueous hydrogen peroxide solution provided in the second stage in the present invention.

[Fig. 2] Fig. 2 illustrates an embodiment in the case where the exhaust gas discharged from the first stage is treated using an apparatus filled with a honeycomb catalyst supporting a noble metal provided in the second stage in the present invention. It is a schematic diagram for doing.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Wada             2-1-1 Yoyogi, Shibuya-ku, Tokyo Zoo             Dochemy Catalyst Co., Ltd. F-term (reference) 4D002 AA14 AA40 AB02 AC10 BA03                       BA05 DA11 DA12 DA16 DA23                       DA24 DA41 DA47 DA52 GA01                       GB03 GB08 HA01                 4D004 AA03 BA04 CA18 CA48 CC09                       CC11                 4D048 AA22 BA30X BA31X BA32Y                       BA33Y BA34X BB02 CC38                       CD01 CD08 DA03 DA06

Claims (6)

[Claims] 1. A method for removing a malodorous substance generated from a composting device, which comprises treating a copper compound and a manganese compound and a deodorant containing clay or activated carbon as a main component in the first step, Exhaust gas from the first stage,
A method for removing a malodorous substance, which comprises passing through an upper part of an aqueous hydrogen peroxide solution provided in the second stage, or treating using a device filled with a catalyst supporting a noble metal. 2. The concentration of the hydrogen peroxide aqueous solution is 1 to 35%.
The method for removing a malodorous substance according to claim 1, wherein 3. The method for removing a malodorous substance according to claim 1, wherein the second-stage catalyst has a honeycomb shape. 4. The method for removing a malodorous substance according to claim 1, wherein the noble metal is Pt, Pd and / or Au. 5. The method for removing a malodorous substance according to claim 3, wherein the amount of the noble metal loaded on the honeycomb-shaped catalyst is 1 g / L to 20 g / L on a honeycomb volume basis. 6. The method according to claim 1, wherein the temperature of the exhaust gas from the composting device is 2
A method for removing a malodorous substance in the range of 0 to 150 ° C.