JP3243382B2 - Removal method of glycol polymer - 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 removing a glycol polymer contained in a water-soluble oil waste such as cutting oil and hydraulic oil.

[0002]

2. Description of the Related Art At present, water-soluble oils containing a glycol polymer are used for cutting, lubrication, hydraulic pumps and the like, and their uses are expanding. However, the waste liquid such as the used water-soluble oil containing the glycol polymer cannot be discarded as it is, and must be treated to decompose and remove the glycol polymer to a level that can be discharged to rivers and oceans. For this reason, the used waste liquid of the water-soluble oil is currently mainly handed over to a specialized treatment company, where water is evaporated and the residue is incinerated. But this method
There is a possibility that harmful substances such as dioxin may be generated in the incinerated material, and enormous heat energy is required to evaporate water, which is economically difficult. Therefore, establishment of a new waste liquid treatment method instead of this method is desired.

[0003] In the conventional wastewater treatment, after gravity separation (coagulation sedimentation or coagulation flotation), microbial treatment with activated sludge is performed. Have been. JP 5
Japanese Patent Application No. 9-69197 discloses a water-soluble oil applied to a conventional wastewater treatment process. That is, the waste liquid containing the water-glycol hydraulic oil is subjected to activated sludge treatment and adsorption treatment with bentonite or activated carbon to remove the waste liquid. However, it is difficult to decompose and remove the water-soluble oil waste liquid containing the glycol polymer by using the activated sludge treatment and the adsorption treatment to a level at which the glycol polymer contained in the treatment liquid can be discharged to rivers and oceans. .
There is also a method of treating a water-soluble oil waste liquid containing a glycol polymer using an ion exchange resin.However, in order to decompose and remove the treated liquid to a level that can be discharged to rivers and oceans,
The exchange of the ion exchange resin must be performed frequently, which is not economical.

Japanese Patent Application Laid-Open No. Hei 6-9721 discloses a method for decomposing a water-soluble polymer having a molecular weight of 1,000 or less obtained by oxidizing or photodegrading an acrylic acid polymer using a microorganism group. is there. For example, in Example 9, the carbon-carbon bond in the main chain of the wet-oxidized acrylic acid-based polymer is broken to reduce the molecular weight of the polymer. When the glycol polymer is wet-oxidized under the oxidation conditions for lowering the molecular weight of the acrylic acid polymer, not only the ether bond but also the carbon-carbon bond of the glycol polymer is cleaved to produce formic acid which is disliked by microorganisms. Therefore, there is a problem that the activity of microorganisms in the activated sludge is suppressed, and the efficiency of removing the glycol polymer by the activated sludge treatment is reduced.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and efficiently removes a glycol polymer from a water-soluble waste solution containing a glycol polymer so that the treated waste solution can be discharged as it is. It is an object to provide a processing method.

[0006]

According to the method for removing a glycol polymer of the present invention, a liquid to be treated containing a glycol polymer is brought into contact with an oxidizing agent, and the liquid to be treated is kept in a liquid phase to obtain a liquid.
It comprises a first step of performing a wet oxidation reaction by heating in a temperature range of 0 to 370 ° C., and a second step of treating the liquid to be treated, which has been oxidized in the first step, with activated sludge.

According to the present invention, after the glycol polymer is oxidized in the first step to a state where microorganisms in the activated sludge are easily decomposed,
In the activated sludge treatment in the second step, the glycol polymer is removed to such an extent that it can be discharged to a river. The glycol polymer referred to in the present invention is a high molecular weight glycol such as polyethylene glycol, polypropylene glycol and polybutylene glycol having an ether bond in the main chain and at least one of the polymer terminals being a hydroxyl group.
Examples of those containing this glycol polymer include water-soluble hydraulic oil, water-soluble cutting oil, water-soluble rolling oil, heat-treating oil, and water-soluble cleaning oil. These waste liquids after use are the main objects.

[0008] The first step involves wet oxidation of the glycol polymer. Wet oxidation is a reaction that oxidizes an object to be treated in a liquid phase such as water.The liquid phase state refers to a case where the entire system is in a liquid state and a case where the entire system is in a semi-solid state. This includes the state in which a liquid phase such as water is present. In the present invention, it is necessary to maintain wet oxidation conditions such that carbon-carbon bonds in the polymer main chain (for example, ethylene bonds of polyethylene glycol) are broken so that activated sludge is not decomposed to formic acid which is disliked by microorganisms. is there. Therefore, the liquid to be treated is appropriately pressurized so as to maintain a liquid phase, and heated in a range of 50 to 370 ° C. to perform wet oxidation. Heating temperature of wet oxidation is 5
If the temperature is lower than 0 ° C., the wet oxidation of the glycol polymer does not sufficiently proceed, which is not preferable. Further, even if the oxidation treatment is performed for a long time at a heating temperature higher than 370 ° C., an effect of further improving the microorganism treatment in the second step cannot be expected. In particular, heating in the range of 100 to 200C is more preferable. The wet oxidation time is usually preferably about 1 to 240 minutes. The wet oxidation conditions are preferably those in the above-mentioned range where the treatment can be performed easily and effectively at low cost.

As the oxidizing agent used in the first step, for example, a gas containing oxygen such as air, hydrogen peroxide, ozone and the like can be used. When the oxidizing agent is in a gaseous state, the oxidizing agent can be brought into contact with the liquid to be treated by blowing a gas into the liquid to be treated kept in a liquid phase. When the oxidizing agent is in a liquid state, the oxidizing agent can be mixed with and contacted with the liquid to be treated. In the second step, the wet oxidation treatment liquid is retained in the activated sludge tank, and treatment with aerobic microorganisms is performed while aeration is performed. The treatment conditions are not particularly limited, but the residence time of the treatment liquid in the activated sludge tank is preferably 3 to 24 hours, and the temperature is preferably in the range of 20 to 40 ° C.

[0010]

According to the method of the present invention, in the first step, the glycol polymer is oxidatively decomposed until the activated sludge microorganisms can be effectively treated, and in the second step, the activated sludge is decomposed by the microorganisms and discharged into a river. The glycol polymer can be removed to the extent possible. Glycol polymers are substances that are easily decomposed by wet oxidation and reduced in molecular weight among organic polymers, but the molecular weight of the liquid containing the glycol polymer of the present invention is reduced under wet oxidation treatment conditions, and the terminal groups are mainly carboxyl. Although it is an acid, the carbon bond is further broken and it is not oxidatively decomposed to formic acid, and can be easily decomposed and removed by microorganisms of activated sludge.

Therefore, the oxidation sludge according to the present invention does not contain a substance such as formic acid which inhibits the action of microorganisms of the activated sludge, so that the activated sludge can efficiently remove the glycol polymer in the oxidation sludge. it can.

[0012]

The present invention will be specifically described below with reference to examples. (Example 1) A water-soluble hydraulic oil containing a glycol polymer (COD 496000 ppm. TOC 330,000 pp
m) was subjected to a wet oxidation treatment for 60 minutes by applying pressure (30 atm) to the water-soluble hydraulic oil at 200 ° C. in an autoclave using air as an oxidizing agent so as to maintain a liquid phase. FIG. 1 shows a graph of the molecular weight distribution of the treated and oxidized untreated hydraulic oil. In FIG. 1, the untreated hydraulic oil has an area of 100 to 1000 as shown by the solid line blank area,
There are zero or more parts. The wet oxidation treatment decomposes to a low molecular weight like a dot-patterned region, and there is no biologically difficult region. The COD removal rate of this oxidized solution (COD of the untreated working bed is defined as A, COD of the treated solution is defined as B, and the COD removal rate is defined as 54−A / B / A).
%Met.

(Example 2) The water-soluble hydraulic oil (C
OD496000 ppm. TOC 330000 ppm)
Then, 5 times equivalent of COD in terms of COD was mixed as an oxidizing agent, and the mixture was subjected to wet oxidation treatment in a liquid state for 60 minutes at 200 ° C. and 30 atm in a pressurized container. In the molecular weight distribution of the obtained processing solution, the amount of the low molecular weight region is reduced and the high molecular weight region is reduced in molecular weight as shown by the dot pattern region in FIG. In FIG. 2, the blank area of the solid line is a graph of the molecular weight distribution of the untreated hydraulic oil.

The COD removal rate of the oxidized solution was 61%. This wet oxidation treatment solution was subjected to activated sludge treatment by a conventional method at 20 ° C. for 12 hours. C after activated sludge treatment
The OD removal rate was 92%. The molecular weight distribution of the glycol polymer after the activated sludge treatment is only present in a small amount in the 1000 to 1000 region as shown by the hatched region in FIG. FIG. 3 is an enlarged view of the polymer region of FIG. 2 three times. The high molecular weight region of the biologically difficult component is reduced by the oxidation treatment, and the oxidation treatment makes the activated sludge more susceptible to microbial treatment, and the activated sludge treatment reduces the polymer side to lower the molecular weight.

Example 3 Water-soluble hydraulic oil (COD496)
000 ppm. (TOC 330,000 ppm) was pressurized using air as an oxidizing agent in a pressurized container at 100 ° C. for 200 minutes to maintain a liquid phase, and the COD removal rate of the processed product was 41%. Was. This wet oxidation treatment liquid was subjected to activated sludge treatment at 20 ° C. for 12 hours. The COD removal rate after the sludge treatment was 84%.

Example 4 Water-soluble hydraulic oil (COD496)
000 ppm. (TOC 330,000 ppm) was pressurized using air as an oxidizing agent at 180 ° C. for 60 minutes in a pressurized container so as to maintain a liquid phase, and the COD removal rate of the processed product was 53%. Was. This wet oxidation treatment liquid was subjected to activated sludge treatment at 20 ° C. for 12 hours. The COD removal rate after the sludge treatment was 98%.

(Example 5) Water-soluble hydraulic oil (COD496)
000 ppm. TOC 330,000 ppm) was subjected to wet oxidation treatment while maintaining the liquid phase in a pressurized container at 300 ° C. for 20 minutes using air as an oxidizing agent.
The OD removal rate was 83%. This wet oxidation treatment solution is
Activated sludge treatment was performed at 0 ° C. for 12 hours. The COD removal rate after the sludge treatment was 88%.

(Example 6) Water-soluble hydraulic oil (COD496)
000 ppm. (TOC 330,000 ppm) was subjected to wet oxidation treatment at 180 ° C. for 200 minutes in a pressurized container using air as an oxidizing agent. As a result, the COD removal rate of the treated product was 58%. This wet oxidation treatment solution is subjected to 12
Activated sludge treatment was performed for hours. The COD removal rate after the sludge treatment was 98%.

(Example 7) Water-soluble hydraulic oil (COD496)
000 ppm. TOC 330,000 ppm) was subjected to wet oxidation treatment at 180 ° C. for 8 minutes in a pressurized container using air as an oxidizing agent.
1%. This wet oxidation treatment solution was subjected to an activated sludge treatment at 20 ° C. for 12 hours. The COD removal rate after the sludge treatment was 96%.

Example 8 Water-soluble hydraulic oil (COD496)
000 ppm. (TOC 330,000 ppm) was subjected to wet oxidation treatment at 70 ° C. for 200 minutes in a pressurized container using air as an oxidizing agent. As a result, the COD removal rate of the treated product was 22%. This wet oxidation treatment solution was subjected to an activated sludge treatment at 20 ° C. for 12 hours. The COD removal rate after the sludge treatment was 57%. (Example 9) Water-soluble hydraulic oil (COD496000 pp)
m, TOC 330,000 ppm) was subjected to wet oxidation treatment at 180 ° C. for 0.5 minute in a pressurized container using air as the oxidizing agent, and the COD removal rate of the treated product was 13%. This wet oxidation treatment solution was subjected to an activated sludge treatment at 20 ° C. for 12 hours. 30% COD removal rate after sludge treatment
Met.

Comparative Example 1 Water-soluble hydraulic oil (COD496)
000 ppm. TOC 330000 ppm) at 20 ° C
For 12 hours. The COD removal rate of the activated sludge treatment liquid was 18%. (Comparative Example 2) Water-soluble hydraulic oil (COD496000 pp
m. (TOC 330,000 ppm) was subjected to a wet oxidation treatment at 40 ° C. for 60 minutes using air as an oxidizing agent. As a result, the COD removal rate of the treated product was 11%. This wet oxidation treatment solution was subjected to an activated sludge treatment at 20 ° C. for 12 hours. The COD removal rate after the sludge treatment was 23%.

According to the above embodiment, the heating temperature is 100 to 20.
In the range of 0 ° C, C after sludge treatment by wet oxidation treatment for a short time
High OD removal rate. If the wet oxidation treatment is not performed as in Comparative Example 1, the COD removal rate is as low as 18%. Comparative Example 2
If the wet oxidation treatment is as low as 40 ° C., the oxidation does not proceed, and the COD removal rate is as low as 23% even after the activated sludge treatment.

[0023]

According to the method of the present invention, the liquid to be treated containing the glycol polymer is subjected to wet oxidation,
Decomposition by the activated sludge treatment becomes easy, and the treatment liquid can be removed until it can be discharged into a river. As a result, the processing cost of the liquid to be treated containing the glycol polymer can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a graph showing the molecular weight distribution of a hydraulic oil wet-oxidized under the conditions of Example 1.

FIG. 2 is a graph showing the molecular weight distribution of a hydraulic oil wet-oxidized under the conditions of Example 2.

FIG. 3 is an enlarged view of the polymer region of FIG. 2 three times.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kengo Ando 1st Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Kojiro Murayama 1st Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation ( 72) Inventor Katsuya Mizutani 4-7-23 Meiji Station, Nakamura-ku, Nagoya City, Aichi Prefecture Inside Toyota Tsusho Co., Ltd. (56) References JP-A-5-23696 (JP, A) JP-A-61-197093 (JP, A) JP-A-54-69253 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 3/12 C02F 9/00 501 C02F 1/72

Claims (3)

(57) [Claims] 1. A liquid to be treated containing a glycol polymer is brought into contact with an oxidizing agent, and the liquid to be treated is kept in a liquid phase state.
A method for removing a glycol polymer, comprising: a first step of performing a wet oxidation reaction by heating in a temperature range of 370 ° C .; and a second step of performing an activated sludge treatment on the liquid to be treated oxidized in the first step. 2. The method according to claim 1, wherein said oxidizing agent is hydrogen peroxide, ozone or oxygen. 3. The heating temperature of the wet oxidation reaction is 100 to 100.
The method for removing a glycol polymer according to claim 1, wherein the temperature is in a range of 200 ° C.