JP2001137869A - Wet process oxidation treating method and wet process oxidation treating device as well as refuse treating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wet process oxidation treating method and wet process oxidation treating device capable of efficiently decomposing organic matter even at a treatment temperature below 180 deg.C and reducing a device cost as well as a refuse treating method. SOLUTION: A carrier of aluminum oxide on which at least either of palladium and platinum is deposited is used as a catalyst for oxidation decomposition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet oxidizing method, a wet oxidizing method, and a refuse treating method for oxidatively decomposing organic substances by heating a liquid while supplying a gas serving as an oxidizing agent to the liquid containing the organic substances. .

[0002]

2. Description of the Related Art For example, liquids and domestic wastewater generated from refuse such as leftovers discharged from restaurants and food stores or inns often contain a large amount of organic substances (organic pollutants). To flow, the organic matter in the liquid is decomposed and, for example, the chemical oxygen demand (chemical oxygen dema
nd: COD) It is necessary to reduce the content of organic substances to below a reference value. In the process of decomposing organic substances in a liquid, conventionally, for example, a biological treatment method of adsorbing and oxidatively decomposing organic substances in a liquid by aerobic microorganisms in the presence of air has been used.

[0003]

In the process of decomposing such an organic substance, a method of oxidatively decomposing the organic substance by heating the liquid while supplying a gas such as air to the liquid is sometimes used. According to this method (wet oxidation treatment method), there are advantages that the apparatus can be made relatively compact and sludge is hardly generated.

However, in this wet oxidation method, when the processing temperature is high, for example, 250 ° C. or higher, organic substances can be effectively decomposed, but the processing temperature is, for example, 180 °
When the temperature is lower than a predetermined temperature such as ° C., it is difficult to effectively decompose organic substances. Further, when the processing temperature is high, the processing pressure must be kept high in order not to boil the liquid, thereby increasing the cost of the apparatus.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a wet oxidation method and a wet oxidation method capable of effectively decomposing organic substances even at a processing temperature of 180 ° C. or less and capable of reducing equipment costs. It is an object of the present invention to provide a processing device and a refuse processing method.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 provides an oxidizing gas to a liquid containing an organic substance and heats the liquid to oxidatively decompose the organic substance. In the wet oxidation treatment method described above, a technique is employed in which at least one of palladium and platinum is held on a carrier of aluminum oxide as a catalyst for the oxidative decomposition. The invention according to claim 2 is directed to a wet oxidation treatment apparatus that supplies a gas serving as an oxidant to a liquid containing an organic substance and heats the liquid to oxidatively decompose the organic substance in a container. A technique is employed in which a catalyst is used in which at least one of palladium and platinum is supported on an aluminum oxide carrier. According to a third aspect of the present invention, in the refuse treatment method, a liquefaction step of liquefying the refuse by a hydrothermal reaction, and supplying a gas serving as an oxidant to the liquid liquefied in the liquefaction step, and discharging the liquid And an oxidative decomposition step of oxidatively decomposing organic substances contained in the liquid by heating. According to a fourth aspect of the present invention, in the refuse treatment method according to the third aspect, in the oxidative decomposition step, at least one of palladium and platinum is held on an aluminum oxide carrier and the oxidative decomposition catalyst is used. The technology used as is adopted.

[0007]

The applicant performed an oxidative decomposition treatment of a liquid containing an organic substance by using the apparatus shown in FIG. 2, and compared the decomposition rates of the organic substance by changing the treatment conditions. The apparatus shown in FIG. 2 includes a container 1 for storing a test liquid containing an organic substance, a heating means 2 for heating the inside of the container 1 to a desired temperature (processing temperature), and a desired pressure (processing pressure) inside the container 1. (Pressure), a gas supply means 4 for supplying a gas as an oxidant into the vessel 1, a cooling means 5 for cooling the liquid after the treatment, and the like. The catalyst can be filled. Reference numeral 6 denotes a temperature detecting means for detecting the temperature in the container 1, and reference numeral 7 denotes a pressure holding valve.

Using the apparatus shown in FIG. 2, an oxidative decomposition reaction was performed on the following two kinds of test liquids using the following three kinds of catalysts. Here, as an index of the decomposition rate, total organic carbon (TOC) and chemical oxygen demand (COD) are used.
Is used. -Test solution (in parentheses indicate concentration, TOC and COD in order) (a) Glucose (2 g / L, 870 mg / L, 13
(00 mg / L) (b) EDTA · 4Na (2 g / L, 700 mg / L,
1200mg / L) (: ethylene diamine tetraacetic
acid tetrasodium salt) ・ Catalyst (a) Palladium / aluminum oxide carrier (Pd / Al
₂ O ₃ ) (b) Platinum / aluminum oxide carrier (Pt / Al ₂ O ₃ ) (c) Palladium / platinum / aluminum oxide carrier (Pt
—Pd / Al ₂ O ₃ )

The graphs shown in FIGS. 3 and 4 show that the processing temperature is 170 ° C., the processing pressure is 1 MPa or less, and the oxidizing agent is
Test solution: glucose (FIG. 3) and EDTA-4Na (FIG. 4) were treated under the conditions of oxygen gas and treatment time: 30 minutes, and (A) an organic substance (TO) without using a catalyst.
C, COD), (B) shows Pd / Al ₂ O ₃
The same decomposition rate is shown when using. As is clear from this figure, both glucose and EDTA / 4Na solution showed a decomposition rate of 90% or more in the presence of the catalyst, indicating that the catalyst (P
d / Al ₂ O ₃ ), it can be seen that the decomposition was greatly promoted. Although not shown here, it was confirmed that other catalysts (Pt / Al ₂ O ₃ , Pt-Pd / Al ₂ O ₃ ) show the same tendency. That is, according to the above means, it is possible to effectively decompose organic substances in the liquid even at a processing temperature of 180 ° C. or less.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a wet oxidation apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a refuse treatment apparatus 10 including a wet oxidation treatment apparatus 12 according to the present embodiment. This refuse treatment apparatus 10 includes a wet oxidation treatment apparatus 12 in addition to the wet oxidation treatment apparatus 12. The apparatus includes a processing liquid storage device 11 for storing the processing liquid to be supplied to the device 12, and a cooling device 13 for cooling the liquid processed by the wet oxidation processing device 12.

The treatment liquid storage device 11 includes a refuse storage section 20 for storing refuse such as leftovers, a hydrothermal reaction section 21 for liquefying the refuse in the refuse storage section 20 using a hydrothermal reaction, and a liquefaction. A liquid storage section 22 for storing a liquid (processing liquid).

The refuse storage unit 20 has crushing means and water supply means (not shown) for storing refuse in a predetermined container and adding water to the stored refuse so that the refuse is appropriately sized to flow. The garbage is crushed and sent to the hydrothermal reaction section 21.

The hydrothermal reaction section 21 has a pressurizing means and a heating means (not shown), and pressurizes the refuse sent from the refuse storage section 20 to a high pressure (for example, 2.0 to 10.0 MPa). (For example, 200 to 300 ° C.)
The refuse is liquefied using a hydrothermal reaction caused by high temperature, and the treated liquid is stored in the liquid storage unit 22.

The wet oxidation processing apparatus 12 applies a processing liquid stored in the processing liquid storage apparatus 11 to a predetermined pressure (for example, 1M).
Pa) and a liquid supply means 30 such as a pump, which supplies the processing liquid downstream and a processing liquid at a predetermined processing temperature (for example, 1).
70 ° C.), a gas supply unit 32 for supplying a gas serving as an oxidizing agent to the processing liquid, and an oxidative decomposition tower 33 as a container in which an oxidation reaction of the processing liquid is performed. I have.

The gas supply unit 32 supplies gas from the lower end of the oxidative decomposition column 33 into the oxidative decomposition column 33 while controlling the flow rate of the gas at a predetermined pressure compressed by, for example, a compressor 34 by a mass flow controller 35. It is supposed to. As a gas to be supplied into the oxidative decomposition tower 33, a gas that functions as an oxidizing agent for an organic substance to be treated, for example, oxygen gas or air is used.

The oxidative decomposition tower 33 includes, for example, a cylindrical vessel 40.
The inside of the container 40 is filled with the catalyst,
1 is provided. Further, a temperature detecting means 42 composed of a thermocouple or the like is provided in the container 40. The temperature detecting means 42 detects the temperature of the processing liquid in the container 40 and, based on the detection result, determines the temperature of the processing liquid. The preheating unit 31 is controlled so as to be maintained at a predetermined temperature.

A liquid supply port 43 for receiving the processing liquid from the preheating section 31 and a gas supply port 44 for receiving the gas from the gas supply section 32 are separately provided below the oxidative decomposition tower 33. A gas dispersion member 45 for dispersing the gas supplied from the gas supply port 44 as uniformly as possible in the liquid in the container 40 is provided. The gas dispersion member 45 is formed, for example, in a porous shape, and has a gas supply port 44.
Is discharged into the liquid in the container 40 in the form of fine bubbles. In addition, a gas discharge part 46 for discharging gas separated from the liquid in the container 40 to the outside is provided at the upper part of the oxidative decomposition tower 33.

The pressure (processing pressure) and temperature (processing temperature) of the processing liquid in the container 40 are determined so that the organic substances contained in the processing liquid can be most effectively oxidized and decomposed in accordance with the type of refuse to be processed. Determined. In the wet oxidation treatment apparatus 12 according to the present invention, by using a catalyst described below, organic substances are oxidized and decomposed at a treatment pressure of 1 MPa or less.

In the wet oxidation treatment apparatus 12 of the present embodiment,
As the catalyst, a catalyst in which at least one of palladium and platinum is supported on an aluminum oxide carrier is used. That is, palladium /
Any of aluminum oxide carrier (Pd / Al ₂ O ₃ ), platinum / aluminum oxide carrier (Pt / Al ₂ O ₃ ), and palladium / platinum / aluminum oxide carrier (Pt-Pd / Al ₂ O ₃ ) . The shape of the catalyst is various, such as a spherical shape and a pellet shape. Further, in order to increase the catalytic activity, the exposed surface of the substance having the catalytic activity is made as large as possible. Further, the above-mentioned catalysts may be used in combination with each other or in combination with another catalyst.

The internal cross-sectional area and length of the oxidative decomposition tower 33 are determined by the reaction in the oxidative decomposition tower 33 according to the processing capacity (processing flow rate per time). (The reference value defined in the above).

The cooling device 13 is provided with a cooling heat exchanger 50 for cooling the liquid treated by the wet oxidation treatment device 12 to a temperature at which the liquid can be discharged downstream, and a cooling heat exchanger 50 downstream of the cooling heat exchanger 50. And a pressure holding valve 51 to be provided. Pressure keeping valve 5
1 sets the pressure in the upstream pipe to a predetermined pressure (for example, 1
When the pressure exceeds a predetermined pressure, the valve is opened and the processing liquid is discharged to the downstream side so as to maintain the pressure at or below MPa.

Next, a description will be given of a waste processing step in the waste processing apparatus 10 configured as described above. In the refuse treatment apparatus 10, first, when refuse such as leftovers is charged, the refuse is crushed and fluidized in the refuse storage unit 20, and then liquefied in the hydrothermal reaction unit 21. At this time, since the waste is liquefied using a hydrothermal reaction, the solid waste can be efficiently liquefied, and some of the pollutants contained in the waste are decomposed by the action of the activated water. Is done.

Subsequently, in the wet oxidation treatment apparatus 12,
The liquefied liquid (processing liquid) is pressurized to, for example, 1 MPa,
This is heated to, for example, 170 ° C. in the preheating unit 31, and the heated processing liquid is supplied into the oxidative decomposition tower 33. Further, a gas (oxidizing gas or air) at a predetermined pressure (for example, 1 MPa) is supplied from the gas supply unit 32 to the oxidative decomposition tower 33. The inside of the oxidative decomposition tower 33 is insulated by the heat retaining means 41, and the gas functions as an oxidizing agent in the high-temperature and high-pressure vessel 40, so that organic substances contained in the processing liquid are decomposed. In the present embodiment, Pd / Al ₂ O ₃ , P
t / Al ₂ O ₃ , or Pt-Pd / Al ₂ O ₃ , which is filled with a catalyst. Due to the activation action of this catalyst, even if the temperature of the processing solution (processing temperature) is 180 ° C. or lower, organic substances Can be efficiently decomposed. Further, since the processing temperature can be set to 180 or less, the liquid does not boil even if the processing pressure is set to 1 MPa or less.

In the present embodiment, the liquid supply port 43 and the gas supply port 44 are separately provided and the gas dispersion member 45 is provided. Is supplied in the form of fine bubbles, and the gas is uniformly dispersed in the container 40 and reacts with the processing liquid, so that the organic matter is efficiently decomposed.

Then, in the cooling device 13, the processing liquid is cooled to a predetermined temperature and then discharged outside. If the specifications of the wet oxidation treatment device 12 are determined so that the amount of the organic matter is equal to or less than a predetermined value, the solid waste is discharged to the sewerage as a liquid or used as water without generating excess sludge. It becomes possible.

That is, the refuse treatment apparatus 10 of the present embodiment
According to the method, by using at least one of palladium and platinum held on a carrier of aluminum oxide as a catalyst for the oxidative decomposition reaction, organic substances can be effectively decomposed even at a processing temperature of 180 ° C. or lower. it can.
Further, since the processing pressure can be reduced to 1 MPa or less, the apparatus can be configured without touching the high pressure gas safety method, and the apparatus cost can be reduced.

It should be noted that the shapes, combinations, and the like of the components shown in the above-described embodiments are merely examples, and can be variously changed based on design requirements without departing from the gist of the present invention. In the embodiment described above,
Although it is configured to process solid waste such as leftovers,
The target to be treated is not limited to solid waste, and may be configured to treat liquid wastewater such as domestic wastewater, for example, by omitting the treatment liquid storage device 11 in the above-described embodiment.

[0028]

As described above, according to the present invention, the following effects can be obtained. In the wet oxidation treatment method for organic matter according to claim 1, the wet oxidation treatment apparatus for organic matter according to claim 2, and the waste treatment method according to claim 3, at least one of palladium and platinum is used as a catalyst for the oxidative decomposition reaction. Can be effectively decomposed even at a processing temperature of 180 ° C. or less by using a material in which is held on a carrier of aluminum oxide. Therefore, the processing pressure can be reduced to 1 MPa or less, and the cost of the apparatus can be reduced.

According to a third aspect of the present invention, the waste is liquefied by a hydrothermal reaction, and the organic matter contained in the liquid is oxidized and decomposed. Therefore, the solid waste is converted into a liquid with almost no excess sludge. It can be discharged to the sewer, and the treated liquid can be directly discharged to the sewer or used as water.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a wet oxidation treatment apparatus and a waste treatment apparatus according to the present invention.

FIG. 2 is a diagram showing a configuration of an apparatus for comparing the decomposition rates of organic substances by a catalyst.

FIG. 3 is a graph showing the decomposition rate of organic substances by the apparatus of FIG.

FIG. 4 is a graph showing the decomposition rate of organic substances by the apparatus of FIG.

[Description of Signs] 10 Waste treatment device 11 Treatment liquid storage device 12 Wet oxidation treatment device 13 Cooling device 21 Hydrothermal reaction unit 30 Liquid supply means 31 Preheating unit 32 Gas supply unit 33 Oxidation decomposition tower 40 Container 43 Liquid supply port 44 Gas Supply port 45 Gas dispersion member

Continued on the front page (72) Inventor Masatada Yamashita 1st place, Shinnakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside the Machinery and Plant Development Center, Ishikawajima-Harima Heavy Industries Co., Ltd. (72) Inventor Katsumi Takahashi, Shinnaka, Isogo-ku, Yokohama-shi, Kanagawa Prefecture No. 1 Haramachi Ishi Kawashima-Harima Heavy Industries Co., Ltd. Machinery & Plant Development Center (72) Inventor Keiichi Miwa No. 1 Shin-Nakaharacho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Ishi Kawashima-Harima Heavy Industries Co., Ltd. Machinery & Plant Development Center F-term ( Reference) 4D050 AA15 AB07 BB01 BC01 BC02 BC06 BD02 BD03 BD06 BD08 CA20 4G069 AA03 BA01A BA01B BB02A BB02B BC72A BC72B BC75A BC75B CA04 CA05 CA07 DA06 EC01X EC04Y EC05Y EC06X EC06Y EC17X EC17Y FB14 FC08

Claims (4)

[Claims] 1. A wet oxidation treatment method comprising supplying a gas serving as an oxidizing agent to a liquid containing an organic substance and heating the liquid to oxidatively decompose the organic substance, wherein at least one of palladium and platinum is converted to aluminum oxide. A method for wet oxidation of an organic substance, wherein a substance held on a carrier is used as a catalyst for the oxidative decomposition. 2. A wet oxidation treatment apparatus in which a gas serving as an oxidant is supplied to a liquid containing an organic substance and the liquid is heated to oxidatively decompose the organic substance in a container. A wet oxidation treatment apparatus, wherein a catalyst in which at least one of platinum is supported on an aluminum oxide carrier is filled. 3. A liquefaction step of liquefying the refuse by a hydrothermal reaction, and supplying a gas serving as an oxidizing agent to the liquid liquefied in the liquefaction step, and heating the liquid to be included in the liquid. An oxidative decomposition step of oxidatively decomposing organic matter. 4. The refuse treatment method according to claim 3, wherein in the oxidative decomposition step, at least one of palladium and platinum supported on an aluminum oxide carrier is used as the oxidative decomposition catalyst. .