JPS6026598B2 - Catalytic oxidation treatment method for organic wastewater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for oxidizing wastewater containing organic matter, that is, a method for oxidizing organic wastewater using a catalyst. The present invention relates to a method in which organic matter is removed by decomposition, a spent catalyst whose activity has decreased or has been deactivated is regenerated by reduction in a liquid, and organic wastewater is continuously oxidized using a catalyst.

Conventionally, catalytic oxidation of organic wastewater is carried out at high temperature and high pressure in the presence of catalysts supporting metals such as iron, cobalt, nickel, ruthenium, rhodium, radium, iridium, platinum, copper, gold, and tungsten, as well as their compounds. The most common method was to carry out this method (Japanese Patent Publication No. 56-42992).

In addition, there are methods of oxidation using catalysts in the presence of these metal ions, such as a method for treating hydrazine-containing wastewater with copper ions (Special Seki No. 56-44091, No. 56-4409).
No. 8) etc. have been proposed. However, in the former method, the oxidation reaction is carried out at high temperature and high pressure, so there are disadvantages such as: (1) the equipment is easily corroded, (2) it must be made into a pressure-resistant container, and (2) a heat source is required. Both had no choice but to be high. Furthermore, the latter method has drawbacks such as the need for a recovery device for these eluted metal ions since metal ions are eluted into the liquid to be treated. Therefore, the present inventors developed a method for treating organic wastewater using reduced steel as a catalytic oxidation treatment method that allows wastewater to be oxidized at lower temperatures and pressures than conventional methods, and in which almost no metal ions are released into the treated water. I came up with a proposal (Tsubaki Seki No. 56-158186).

Furthermore, the present inventors have developed an oxidation method using a Raney steel catalyst (Tokko No. 55-180535, (Japanese Unexamined Patent Publication No. 55-180535), which has higher catalytic activity than reduced copper and can treat various wastewaters at room temperature and pressure.
7-105287), special face No. 56-36461, (
Tokufatsu (Sho 57-153792), Tokugao (Sho 56-7223)
No. 5, (Unexamined Japanese Patent Publication No. 57-187093), Tokuse Sho 56-
No. 209366, (Special Seki No. 58-112088)) was proposed.

In addition, we found that various kinds of wastewater such as domestic sewage, food factory wastewater, petroleum and petrochemical factory wastewater can be treated using Raney steel catalysts, but in this case, Raney steel catalysts had the disadvantage that they were easily contaminated. . The object of the present invention is to provide a method for oxidizing organic wastewater using a catalyst, which eliminates the above-mentioned drawbacks.

That is, the present invention oxidizes wastewater containing organic matter by contacting it with one or more selected from the group consisting of pure oxygen, oxygen-containing gas, and oxygen-generating substances in the presence of a Raney steel catalyst. The present invention provides a method for oxidizing organic wastewater using a catalyst, which is characterized by reducing and regenerating a used catalyst in a liquid while treating it.

According to the present invention, it is possible to treat organic wastewater and regenerate a catalyst whose activity has decreased or has been deactivated in a reaction tank at room temperature and pressure, thereby eliminating the need for complicated operations such as replacing the catalyst. In addition, since it is regenerated in liquid, there is no problem of Raney steel being deactivated by exposure to air, and catalytic oxidation can be carried out continuously.
Moreover, it can be carried out smoothly.

The catalytic oxidation treatment method of the present invention can be applied to any wastewater as long as it contains organic matter.
In addition to PVA (polyvinyl alcohol) wastewater, cyanide-containing wastewater, thiocyanide-containing wastewater, hydrazine-containing wastewater, etc.
It can also be applied to various types of wastewater such as domestic wastewater, food factory wastewater, petroleum and petrochemical factory wastewater, etc.

The Raney steel catalyst used in the present invention refers to copper and one or two metals (magnesium, aluminum, zinc, iron, nickel, tin, lead, silica, titanium, boron, etc.) that are attacked by water, alkalis, acids, etc. It means something obtained by reacting an alkaline aqueous solution such as sodium hydroxide or an acid aqueous solution such as hydrochloric acid to an alloy with at least one species, and the amount of metals other than copper eluted by the alkali or acid is not particularly limited.

Also, the weight ratio of copper and metals other than copper is usually 1:
1 is used, but it is not limited to this ratio. An example of a Raney steel catalyst preparation method is as follows: weight ratio: 1:
When a sodium hydroxide aqueous solution is applied to the copper-aluminum alloy of No. 1, a dilation reaction occurs rapidly, and a Raney copper catalyst in which 90% or more of the aluminum in the alloy is eluted is obtained. Thus, the Raney steel catalyst becomes porous due to the elution of metals other than copper. The Raney steel catalyst obtained as described above is usually adjusted to a particle size of about 200 mesh from the standpoint of strength, but it is desirable to select an appropriate particle size depending on the properties of the wastewater and the method of contact with the wastewater.
It is not necessarily necessary to be limited by this granularity.

Next, there is no particular restriction on the method of contacting the waste water with the Raney steel catalyst, and any method such as a complete mixing type, fixed bed, fluidized bed, or moving bed may be used.

In addition, the oxygen required for oxidative decomposition can be either dissolved in the raw water in advance or supplied directly in the reaction tank, but direct supply, which allows the amount of oxygen required for the reaction to be added sequentially, is better. This is preferable for preventing oxidation of the catalyst. Further, the oxygen may be pure oxygen gas, liquid oxygen, air, waste gas containing oxygen, or a substance that generates oxygen such as hydrogen peroxide, ozone, etc. alone or in combination. Regarding the amount of oxygen supplied, the concentration of organic substances contained is measured using commonly used indicators such as COD (chemical oxygen demand), BOD (biological oxygen demand), and TOD (total oxygen demand). In that case, those 1.1~
It is usually sufficient to supply about 1.5 times as much oxygen. Further, the reaction temperature and reaction pressure are usually normal temperature and normal pressure, and there is no need to particularly raise the temperature or apply pressure. However, if it is desired to increase the reaction efficiency, this objective can be achieved by increasing the temperature or applying pressure. In addition, the treated water may contain metal ions such as steel ions due to the catalyst used, but in such cases, after oxidation by the catalyst, the water is treated with a coagulation sedimentation device, ion exchanger Okuwaki fat, chelate resin. These can be removed by installing a device or the like. Methods for regenerating catalysts that have been deactivated or whose activity has decreased after treating organic wastewater include methods for reducing and regenerating catalysts in liquid using a commonly used reducing agent, and methods for regenerating catalysts by redeploying them in liquid. A method that exposes the catalyst surface is preferred.

When a reducing agent is used to reduce and regenerate the catalyst in a liquid, the reducing agent may be either one that decomposes in water to generate hydrogen or one that generates hydrogen upon contact with the catalyst.
Examples of the former include sodium borohydride, potassium borohydride, lithium borohydride, aluminum borohydride, lithium aluminum hydride, sodium hydride, potassium hydride, lithium hydride, calcium hydride, nickel hydride, Examples include substances such as cobalt hydride.

Examples of the latter include, but are not limited to, hydrazine, formalin, methanol, formate, and the like. Although these reducing agents are normally used to regenerate catalysts under elevated temperature and pressure, the present inventors have discovered that in the case of regenerating Raney steel catalysts, they can be regenerated even at room temperature and pressure.
However, as described above, there is no problem in regenerating the material under heating and pressurization if necessary. The concentration of the reducing agent used for regeneration varies depending on the type of reducing agent, temperature, pressure, contact time, etc., but is usually 0.1 to 20%. Although the regeneration time also varies depending on the type and concentration of the reducing agent, and is difficult to define unambiguously, it is usually possible to sufficiently regenerate the catalyst in less than one hour. Further, when regenerating a deactivated or decreased activity catalyst by redeploying the catalyst, it is preferable to redeploy the catalyst using a caustic alkali such as sodium hydroxide or potassium hydroxide.

In this case, the developing temperature is usually 30 to 90°C, the pressure is normal pressure, and the concentration of caustic alkali is 1 to 4%. However, in the case of redeployment, since the purpose is to expose a new catalyst surface, it is more preferable to develop slowly at a relatively low temperature, that is, 40 to 60°C, and to control the reaction so that it does not proceed significantly. Further, it is more preferable that the concentration of the caustic alkali used is about 0.1 to 2 K%. Although the redeployment time varies depending on the alkali concentration, the developing temperature, etc., less than one hour is usually sufficient. Note that the reducing agent is normally dissolved directly in water or wastewater and used as a regenerating solution in the form of a solution, but in the case of a substance that generates hydrogen when it comes into contact with water, it is used as a strong alkaline solution to prevent the generation of hydrogen until it is used. It is preferable to leave it there.

Further, for redeployment of the catalyst, a solution of caustic alkali dissolved in water or directly in waste water can be used. Regeneration of the catalyst may be carried out during the reaction process, and there is no need to extract the entire amount of the catalyst from the reaction vessel and regenerate it.

For example, in the case of a fixed bed, complete continuous treatment of wastewater is possible by using a plurality of reaction tanks and performing switching operations. Also,
In the case of regeneration using a reducing agent, it is sufficient to stop the supply of oxygen even for a single turret, combine the reducing agent to regenerate the catalyst, and then re-supply oxygen for treatment. In addition, in the case of a fluidized bed, moving bed, or completely mixed type, it is possible to perform a continuous process in which a part of the catalyst is extracted continuously or intermittently and the regenerated catalyst is supplied at the same time. It would be nice if there was a tank. Furthermore, in the case of regeneration using a reducing agent, no harmful substances remain in the regenerating liquid, so there is no need to newly process the regenerating liquid.
One way to know whether the catalyst has been deactivated during wastewater treatment is to directly measure the concentration of organic matter in the wastewater, but other methods include measuring the oxidation/reduction potential in the reaction tank or checking if the catalyst has deactivated. It can also be detected by measuring copper ions that are eluted into the treated water due to deactivation.

As described above, according to the present invention, various organic wastewaters can be treated at room temperature and pressure by supplying oxygen in the presence of a Raney steel catalyst, and even when the catalyst is deactivated or its activity is reduced. Since it can be regenerated in liquid at room temperature and pressure, there is no need for harsh treatment conditions and regeneration conditions such as high temperature and high pressure as in conventional catalytic oxidation treatment methods, which significantly reduces the pressure and heat resistance of the reaction tank. Not only can this be achieved, but the power costs required to maintain high temperatures and pressures can be reduced, resulting in significant reductions in construction and operating costs.

Moreover, since catalyst regeneration usually takes less than one hour, wastewater treatment can be carried out efficiently. Furthermore, since the catalyst can be regenerated in liquid, the problem of Raney steel being exposed to air and deteriorating can also be solved.

Furthermore, when a reducing agent is used to regenerate the catalyst, no harmful substances caused by the reducing agent remain in the regenerating liquid, so it can be discharged as is along with the treated water, eliminating the need to reprocess the regenerating liquid. be able to.

The present invention can treat various types of wastewater simply by supplying oxygen in the presence of a Raney steel catalyst. It can be widely applied not only as a pre-treatment and post-treatment for microbial treatments such as, but also as a pre-treatment and post-treatment for physicochemical treatments such as activated carbon adsorption, reverse osmosis, and chlorine oxidation.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to examples, but the present invention is not limited to the following examples.

Example 1 Tower-type reaction tank 1 (18 x 20 days,
(made of polyvinyl chloride) is filled with Raney copper catalyst, raw water a- is supplied to the lower part of the reaction tank by the raw water pump 2, and at the same time, the air necessary for oxidation treatment is passed through the catalyst packed bed 3 in an upward flow. It was supplied through filter 4 and oxidized at room temperature and pressure.

To regenerate the catalyst, first stop the supply of raw water and air to the reaction tank 1, and circulate and supply the regenerated liquid in the regenerated liquid tank 5 to the lower part of the port-type reaction tank 1 for a certain period of time using the regenerated liquid circulation pump 6. This was done by

Note that the catalyst was regenerated at regular intervals. Thereafter, the regeneration liquid circulation pump 6 was stopped, and raw water and air were again supplied to the tower-type reaction tank 1 to continue oxidation using the catalyst. The experimental conditions and regeneration conditions are shown below.・The experimental results are shown in Table 1. Experimental conditions Raw water: Petrochemical factory effluent raw water flow rate: 20cc/Hr Raney steel catalyst loading amount: 60cc Raney steel catalyst properties: particle size 15-24 mesh, copper capacity 9
0.4wt%, aluminum content 9. Sakaki t%, manufactured by Kawaken Fine Chemical ■ LHSV: 0.33 Reaction pressure: Normal pressure Air flow rate: 1〆/Hr Regeneration conditions Regeneration liquid: Sodium borohydride solution (4% sodium borohydride solution in sodium hydroxide solution) 1 t% of fence) Regeneration liquid volume: 500cc Regeneration liquid circulation amount: 3/Shoes Regeneration time: 3 minutes Regeneration temperature: 24℃ Regeneration pressure: Normal pressure Regeneration interval: 30 days Values in Table 1 pocket Yes, the effect is also flat.

From Table 1, it can be seen that the performance of the catalyst did not deteriorate even after four regenerations (approximately 5 months of operation), and wastewater could be continuously treated by repeated regeneration.

Example 2 5Fill out raw water 5 in the beaker and add Raney steel catalyst 200
cc was added, and the waste water was oxidized by a catalyst at normal temperature and pressure while supplying air and slowly pressing the waste water with a fly azusa machine.

After the reaction was carried out for 3 hours, the supply of air and the porridge by pseudo-speculation were stopped, the Raney copper catalyst was allowed to settle, the treated water was removed by decantation, and 2 t% of pure water was added to add 2 t% of water. Add 15 cc of sodium oxide solution 9 times every 4 minutes (
The total amount added was 135 cc), and the five female catalysts were redeployed while slowly stirring.

At this time, in order to prevent the liquid from overflowing, the liquid temperature was controlled to 45-5000 in a water bath. After the redeployment of the catalyst is completed, discard the regenerated liquid by decantation 1. After washing the regenerated catalyst 5 times with pure water, add 5 new raw water.
Oxidation was continued by adding water. Experiments were conducted by repeating oxidation using such a catalyst and regeneration of the catalyst. The experimental conditions and regeneration conditions are shown below.

The experimental results are shown in Table 2. Experimental conditions Raw water: Drainage from the cafeteria treated in a sand furnace Amount of raw water: 5 days Amount of Raney copper catalyst added: 200 cc Raney steel catalyst properties: Particle size 200 mesh, steel shed amount 96.
2wt%, aluminum content 3.8wt%, manufactured by Kawaken Fine Chemicals Reaction time: 3 hours Reaction pressure: Normal pressure Air flow rate: 150 pm/Hr Regeneration conditions Regeneration liquid: 2% sodium hydroxide aqueous solution Regeneration liquid addition amount: 135cc Regeneration time: 5 minutes Regeneration temperature: 45 to 50 CO Regeneration pressure: Normal pressure Table 2 *The table on duty is Hiraina Ura.

From Table 2, it can be seen that the catalyst did not deteriorate even after repeated regeneration six times, and sufficient wastewater treatment was possible.

Example 3 An experiment similar to Example 1 was conducted using the apparatus shown in FIG.

In this experiment, underground water was used as the raw water, and formalin aqueous solution was used as the regenerating liquid. The experimental conditions and regeneration conditions are shown below.

The experimental results are shown in Table 3. Experimental conditions Raw water: Sedimentation and separation of underground water Raw water flow rate: 30cc/Raney steel catalyst loading amount: 60cc Raney steel catalyst properties: particle size 24-36 mesh, total copper content 8
7.7 wt%, aluminum content 12.3 wt%, LHSV manufactured by Kawaken Fine Chemical ■: 0.5 Reaction pressure: normal pressure Air flow rate: 2 nights/Hr Regeneration conditions Regeneration liquid: 13% formalin aqueous solution Regeneration liquid amount: 1 Regeneration liquid circulation amount: 3 evenings/Hr Regeneration time: 1 hour Regeneration temperature: 28q○ Regeneration pressure: Normal pressure Regeneration interval: 6th day 3rd * Sardine value Misakase ura in the table.

From Table 3, it can be seen that even after four times of regeneration (continuous operation for about one month), no deterioration of the treated water due to a decrease in catalyst performance was observed, and stable treatment was possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of an apparatus used in an embodiment of the present invention. a... Raw water, b... Treated water, c... Air,
1... Tower type reaction tank, 2... Raw water pump, 3... Catalyst packed bed, 4... Glass filter, 5... Regeneration liquid tank, 6...
・Regeneration liquid circulation pump, 7... Porous plate, 8...
...Regeneration liquid circulation line. Figure 1

Claims (1)

[Claims] 1. Contacting wastewater containing organic matter with one or more selected from the group consisting of pure oxygen, an oxygen-containing gas, and a substance that generates oxygen in the presence of a Raney copper catalyst. A catalytic oxidation treatment method for organic wastewater, characterized in that the oxidation treatment is performed using a catalyst, and the spent catalyst is regenerated by reduction in a liquid. 2. The method according to claim 1, in which a reducing agent is used to regenerate the spent catalyst in a liquid. 3. The method according to claim 2, wherein the reducing agent is a substance that decomposes in water to generate hydrogen. 4 Substances that decompose in water and generate hydrogen include sodium borohydride, potassium borohydride, lithium borohydride, aluminum borohydride, lithium aluminum hydride, sodium hydride, potassium hydride, lithium hydride, and hydride. 4. The method according to claim 3, wherein the hydride is any one of calcium, nickel hydride, and cobalt hydride. 5. The method according to claim 4, wherein the regeneration time of the spent catalyst in the liquid is less than one hour. 6. The method according to claim 2, wherein the ring-forming agent is a substance that generates hydrogen upon contact with a catalyst. 7. The substance that generates hydrogen when it comes into contact with the catalyst is hydrazine. formalin. 7. The method according to claim 6, wherein the substance is one or more substances selected from methanol and formate. 8. The method according to claim 1, in which the spent catalyst is regenerated in a liquid by redeploying the catalyst. 9. The method according to claim 8, wherein the catalyst is redeployed with a caustic alkali. 10. The method of claim 9, wherein the catalyst redeployment time is less than 1 hour.