JP2792481B2 - Treatment method for wastewater containing sulfoxides - 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 treating wastewater containing, as a pollutant, a sulfoxide-type organic sulfur compound (R-SO-R ': R, R' is a hydrocarbon group). SR ′), mercaptans (RS)
The present invention relates to a method for treating wastewater without generating malodorous sulfides such as H) and hydrogen sulfide (H ₂ S).

[0002]

2. Description of the Related Art At present, about 3,000 tons of dimethyl sulfoxide is produced in Japan every year.
It is used in the synthesis of agricultural chemicals, solvents for dyes and pigments, or stripping / cleaning agents, etc., and a large amount of sulfoxide-containing wastewater is produced with its industrial use.

Conventionally, organic matter (COD component, BOD component)
In the treatment of wastewater containing, organic matter decomposition treatment is an important process, and is roughly classified into a chemical treatment method and a physiological treatment method.

As a chemical treatment, potassium permanganate (KMnO ₄ ), hydrogen peroxide (H ₂ O ₂ ), chlorine (C
l ₂ ), an oxidizing agent treatment such as sodium hypochlorite (NaOCl), an ozone oxidation treatment, and an electrolytic oxidation treatment method are employed. By performing these oxidation treatments on the wastewater containing sulfoxides, the COD value is reduced. Can be completely reduced.

[0005] A biological treatment method represented by the activated sludge method is a method of decomposing organic substances by the action of microorganisms, and has a function of coagulating, adsorbing, decomposing, and precipitating soluble organic substances. This is an effective treatment method for organic wastewater. Sulfoxides are not biodegraded under aerobic conditions such as the activated sludge process, so treatment under anaerobic conditions is employed. After the metabolite is generated, sulfuric acid is finally generated and the process is completed.

[0006]

However, in the above-mentioned conventional processing techniques, among the techniques of chemically oxidizing, the electrolytic oxidation processing method can perform the processing by using only a small amount of electrolyte as an additive. Although there is almost no effect on the subsequent process, when this technology is applied to sulfoxide-containing wastewater, the oxidation reaction at the anode and the reduction reaction at the cathode side proceed at the same time, producing sulfides, which are malodorous substances. There was a problem.

The oxidation reaction also involves sulfones (R-SO _2-
The reaction is completed when R ′) is generated, and no further oxidative decomposition reaction proceeds.

[0008] On the other hand, when an oxidation treatment with an oxidizing agent of sodium hypochlorite or hydrogen peroxide or ozone is performed, no odorous substances are generated, but as in the case of electrolytic oxidation, sulfones are produced as a final product. However, no further oxidative decomposition reaction proceeds.

In general, when wastewater containing organic matter is completely oxidized and decomposed, carbon dioxide and water are obtained as final products, and when the wastewater contains sulfur compounds, it is removed. Although it must be sulfuric acid, in the case of the sulfoxide-containing wastewater, the chemical treatment as described above does not demineralize the sulfoxide-containing wastewater.
Although a decrease is seen as the D value, the TOC (or BOD)
The value did not decrease completely.

On the other hand, when the biological treatment method is applied to wastewater containing an organic sulfur compound such as sulfoxides, the sulfoxides are not biodegraded under aerobic conditions such as the activated sludge method, and the sulfoxides are not treated. Spills into water. Decomposition progresses relatively easily under anaerobic conditions, but metabolites such as sulfides, mercaptans, disulfides, and hydrogen sulfide, which are malodorous substances, are generated during decomposition under anaerobic conditions.
There was a problem that odors from wastewater diffused into the atmosphere and deteriorated the environment. In addition, sulfoxides that were not decomposed in the aeration tank even in the activated sludge method were easily decomposed in a sludge settling tank or the like which is subjected to anaerobic conditions during the process, and odor generation was a problem.

It is an object of the present invention to provide a method for treating sulfoxide-containing wastewater which prevents the generation of sulfur-based malodorous substances and sufficiently decomposes and removes TOC or BOD components.

[0012]

In order to achieve the above object, a method for treating a sulfoxide-containing wastewater according to the present invention comprises causing hydrogen peroxide or ozone to coexist in an organic wastewater containing a sulfoxide-organic sulfur compound. The organic wastewater is irradiated with light rays for photoreaction to decompose sulfoxides and organic sulfur compounds.

When hydrogen peroxide coexists in the organic wastewater, the decomposition of the organic sulfur compound of the sulfoxide type is as follows:
Hydroxyl radical is generated by photoreaction, and this is reacted with the carbon-sulfur bond dissociated part of sulfoxides to generate sulfonic acids, and the generated sulfonic acid is decomposed into sulfuric acid by photoreaction and completely mineralized. Things.

In the case of dissolving ozone in the organic wastewater, the decomposition of the organic sulfur compound of sulfoxides generates active oxygen by a photoreaction of ozone, and reacts it with a dissociated portion of carbon-sulfur bond of sulfoxides. Sulfonic acids are generated, and the generated sulfonic acids are decomposed into sulfuric acid by a photoreaction to completely perform a mineralization treatment.

Further, the decomposition of the organic sulfur compound of the sulfoxides is performed by decomposing the organic sulfur compound of the sulfoxides to the form of sulfonic acid, and then decomposing under aerobic conditions in a biological treatment, and completely demineralizing. Is what you do.

The light beam for photoreaction has a wavelength having an energy higher than the binding energy of the carbon-sulfur bond of the sulfoxide type organic sulfur compound.

The light beam for photoreaction is ultraviolet light.

Ultraviolet light is a kind of electromagnetic wave and has a relatively short wavelength (1
(400 nm to 400 nm), and the shorter the wavelength, the higher the energy. By irradiating light having a wavelength higher than the binding energy of the carbon-sulfur bond of the sulfoxides organic sulfur compound, the carbon-sulfur bonds of the sulfoxides can be dissociated.

In the case where hydrogen peroxide coexists in the aqueous solution, the hydroxyl radical (OH
), Which reacts with the carbon-sulfur bond dissociating moiety of the sulfoxides, resulting in sulfonic acids (R-SO
₃ H).

When ozone is dissolved in an aqueous solution, a photoreaction produces hydroxyl radicals (OH.), Which react with the carbon-sulfur bond dissociating portion of sulfoxides, and as a result, sulfinic acids (R-SO ₂ H). The sulfinic acid generated here immediately reacts with ozone or active oxygen generated by the photoreaction of ozone,
The sulfonic acids (R-SO ₃ H).

Hydrogen peroxide or ozone is allowed to coexist in the wastewater, and the sulfonic acid generated as described above is further decomposed into sulfuric acid (H ₂ SO ₄ ) by a similar photoreaction, and is completely mineralized. In addition, sulfonic acid organic sulfur compounds are decomposed to sulfuric acid without generating sulfur-based malodorous substances by performing a biological treatment under aerobic conditions.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

The method for treating a sulfoxide-containing wastewater according to the present invention has a basic configuration in which hydrogen peroxide or ozone coexists in an organic wastewater containing a sulfoxide-organic sulfur compound, and the organic wastewater is irradiated with a light beam for photoreaction. And decomposes the sulfoxides organic sulfur compounds.

There are two methods for decomposing a sulfoxide or organic sulfur compound based on a photoreaction.

First, in the first decomposition treatment, a hydroxyl radical is generated by a photoreaction, and this is reacted with a carbon-sulfur bond dissociated portion of a sulfoxide to generate a sulfonic acid, and the generated sulfonic acid is converted to a sulfuric acid by a photoreaction. This is a method of decomposing to complete mineralization.

The second decomposition treatment is a method in which an organic sulfur compound of sulfoxides is decomposed to a sulfonic acid form, and then decomposed under aerobic conditions in a biological treatment.

In the above-described method, the same effect can be obtained regardless of the processing.

(Embodiment 1) Next, an embodiment of the present invention will be described. The method for treating sulfoxide-containing wastewater according to the present invention shown in FIG. 1 is a specific example of implementing the former treatment method when hydrogen peroxide coexists in the wastewater, and FIG. 1 shows a method for treating sulfoxide-containing wastewater. It is a flowchart showing a treatment method of the present invention in which hydrogen peroxide coexists and decomposes sulfoxides organic sulfur compounds by irradiating ultraviolet rays,
FIG. 2 is a graph showing the change in the concentration of dimethyl sulfoxide and the reaction products (methanesulfonic acid, sulfuric acid) with the irradiation amount of ultraviolet rays.

First, dimethyl sulfoxide (CH ₃ SO
10 ml of hydrogen peroxide solution (30%) was added to CH ₃ ) -containing waste water (2500 mg / 1500 ml), and this was flowed into a quartz cell in an ultraviolet irradiation device by a liquid sending pump and circulated.

Subsequently, a low-pressure mercury lamp was used as a light source for irradiating ultraviolet rays, and the dimethyl sulfoxide-containing wastewater to which hydrogen peroxide had been added was irradiated with ultraviolet rays to perform a photoreaction. Here, the temperature of the reaction solution was maintained at about 25 ° C. using cooling water.

As a result, the concentration of dimethyl sulfoxide decreased with the irradiation of ultraviolet rays, methanesulfonic acid (CH ₃ SO ₃ H) was produced as an intermediate product, and finally sulfuric acid (H ₂ SO ₄ ) was produced. (Concentration: 2900 mg / l).
The TOC value of the treated water was 1 mg / l or less. No malodor such as methyl mercaptan was generated during the decomposition process.

(Embodiment 2) FIG. 3 is a flowchart showing a processing method according to Embodiment 2 of the present invention. The method for treating sulfoxide acid-containing wastewater according to the present invention shown in FIG. 3 is a specific example of the latter treatment method when hydrogen peroxide coexists in the wastewater.

First, dimethyl sulfoxide-containing wastewater (2
500mg / 1500ml) wastewater with hydrogen peroxide solution (3
(0%) was added, and a photoreaction was performed with an ultraviolet irradiation device in the same manner as in Example 1. Dimethyl sulfoxide was completely decomposed and methanesulfonic acid (2900 mg /
When 1) was formed, the photolysis reaction was stopped.

Subsequently, the produced methanesulfonic acid-containing wastewater is neutralized with an aqueous sodium hydroxide solution, and the resulting wastewater is reduced to about 1%.
0-fold dilution, NH ₄ Cl 300 mg / l, K ₂ HPO
₄ 100 mg / l, MgSO ₄ 25 mg / l, KCl
_{25mg / l, FeCl 2 0.2mg /} l, was dissolved at a yeast extract 30 mg / l. The activated sludge was acclimated to methanesulfonic acid for one month in advance, and the decomposition ability of methanesulfonic acid under aerobic conditions was confirmed by increasing the sulfate ion concentration during the acclimation process. Prepare a 1L aeration tank and add M
LSS was added so as to be 3000 mg / l, and the temperature was kept at 25 ° C. The aeration tank used had a columnar shape so that the sludge was sufficiently stirred, and was stirred with the stirrer together with the aeration. Since the pH was lowered with the decomposition, the pH was controlled at 7 with a 1N aqueous sodium hydroxide solution. The residence time was set to 10 hours, and the dimethyl sulfone-containing wastewater diluted at 50 ml / hr was flowed into the aeration tank. The treated water was discharged using a filter separator without providing a sedimentation tank. After 10 hours, the concentration of methanesulfonic acid in the effluent was 0 mg / l (liter), and no malodor such as methyl mercaptan was generated during the decomposition process. The TOC value of the treated water was 2 mg / l.

In this embodiment, the photodecomposition reaction is terminated when dimethylsulfoxide is converted to methanesulfonic acid, so that irradiation with ultraviolet rays can be performed in a very short time and the running cost of the treatment can be significantly reduced.

(Embodiment 3) Next, Embodiment 3 of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. The method for treating sulfoxide-containing wastewater according to the present invention shown in FIG. 4 is a specific example of implementing the former treatment method when ozone is dissolved in wastewater.

Here, FIGS. 4 and 5 are a flow chart showing the treatment method of the present invention in which ozone is coexistent in the sulfoxide-containing wastewater and irradiate ultraviolet rays to decompose the sulfoxide-organic sulfur compounds, and FIG. It is a schematic diagram. FIG. 6 is a graph showing changes in the concentrations of dimethyl sulfoxide and reaction products (methanesulfonic acid and sulfuric acid) with the irradiation amount of ultraviolet rays.

The ultraviolet irradiation apparatus 1 shown in FIG. 5 comprises a low-pressure mercury lamp 3 having a power supply 2 for a low-pressure mercury lamp of 400 W and a UV reactor 4 made of quartz having a light irradiation area of 100 cm ² . A diffusion ball 6 for blowing ozone is provided below the ozone treatment tank 5 having a capacity of 1000 ml, so that ozone can be sufficiently dissolved in the wastewater.

First, dimethyl sulfoxide (CH ₃ SO
CH ₃ ) -containing wastewater 7 (2500 mg / 1500 ml) was flowed into the ozone treatment tank 5. The air having an air flow rate of 50 l / h is supplied by the air pump 8 to the ozone
The ozone-containing gas 10 was adjusted to 0 ppm, and the ozone-containing gas 10 was fed into the dimethylsulfoxide-containing wastewater through the ozone blowing air diffuser ball 6 and dissolved therein. The wastewater containing ozone-dissolved dimethyl sulfoxide was flowed into the quartz reaction tank 4 in the ultraviolet irradiation device 1 by the liquid sending pump 11 and circulated to the ozone treatment tank 5.

Subsequently, ultraviolet light was irradiated to the quartz ultraviolet ray reaction tank 4 by the low-pressure mercury lamp 3 to carry out a photoreaction of the dimethyl sulfoxide-containing wastewater. Since the concentration of ozone dissolved in the wastewater by the light reaction decreases, ozone gas is continuously blown in the ozone treatment tank 5 so that ozone is always dissolved in the treatment liquid.

As a result, as shown in FIG. 6, the concentration of dimethyl sulfoxide decreases with the irradiation of ultraviolet rays, and methanesulfonic acid (CH ₃ SO ₃ H) is generated as an intermediate product, and finally sulfuric acid (CH ₃ SO ₃ H) is formed. H ₂ SO ₄ ) (concentration: 2)
900 mg / l). The TOC value of the treated water was 1 mg /
1 or less. Further, no malodorous substances such as methyl mercaptan and hydrogen sulfide were generated during the decomposition process.

(Embodiment 4) Next, Embodiment 4 of the present invention will be described with reference to FIG.
This will be described with reference to FIG. The method for treating sulfoxide acid-containing wastewater according to the present invention shown in FIG. 7 is a specific example of the latter treatment method when ozone is dissolved in wastewater.

FIG. 7 shows the results for the sulfoxide-containing wastewater.
It is a flowchart which shows the processing method of this invention which produces | generates a sulfonic acid by coexisting ozone, and irradiates ultraviolet rays, and performs a biological treatment.

As in Example 3, dimethyl sulfoxide (CH ₃ SOCH ₃ ) -containing wastewater (2
(500 mg / 1500 ml), an ozone gas was supplied, and a photoreaction was performed by an ultraviolet irradiation device. When the dimethyl sulfoxide was completely decomposed and metal sulfonic acid (2900 mg / l) was generated, the photolysis reaction was stopped.

Subsequently, the produced metal sulfonic acid-containing wastewater is neutralized with an aqueous sodium hydroxide solution, and then the resulting wastewater is reduced to about 1%.
0-fold dilution, NH ₄ Cl 300 mg / l, K ₂ HPO
₄ 100 mg / l, MgSO ₄ 25 mg / l, KCl
_{25mg / l, FeCl 2 0.2mg /} l, was dissolved at a yeast extract 30 mg / l. The activated sludge was acclimated to the metal sulfonic acid for one month in advance, and the decomposition ability of the metal sulfonic acid under aerobic conditions was confirmed by increasing the sulfate ion concentration during the acclimation process. An aeration tank having a capacity of 1000 ml was prepared, MLSS was added to the aeration tank so as to be 3000 mg / l, the temperature was maintained at 25 ° C, and the mixture was stirred with a roller. Since the pH was lowered with the decomposition, the pH was controlled at 7 with a 1N aqueous sodium hydroxide solution. The residence time was set to 10 hours, and the dimethyl sulfone-containing wastewater diluted at 50 ml / hr was flowed into the aeration tank. The treated water was discharged using a filter separator without providing a sedimentation tank. After 10 hours, the concentration of methanesulfonic acid in the effluent was 0 mg / l, and no malodor such as methyl mercaptan was generated during the decomposition process. The TOC value of the treated water was 2 mg / l.

In this embodiment, the photodecomposition reaction is terminated when dimethylsulfoxide is converted to methanesulfonic acid, so that irradiation with ultraviolet rays can be performed in a very short time and the running cost of the treatment can be significantly reduced.

(Comparative Example 1) A dimethyl sulfoxide-containing wastewater (2500 mg / 1500 ml) was prepared in the same manner as in Examples 1 and 3 without adding hydrogen peroxide solution and without supplying ozone gas. The photolysis reaction was performed in the device. As a result, a slight decrease in the dimethyl sulfoxide concentration was confirmed. However, in this treatment method, the treatment was stopped because sulfur-based malodorous substances such as methyl mercaptan and hydrogen sulfide were generated from the waste liquid.

(Comparative Example 2) Hydrogen peroxide or ozone was allowed to coexist with dimethyl sulfoxide-containing wastewater (2500 mg / 1500 ml).
After dilution to 0-fold, the same biological treatment as in Example 2 and Example 4 was performed by the activated sludge method. As a result, the TOC concentration in the treated water was 78 mg / l, the dimethyl sulfoxide was 249 mg / l, and it was confirmed that dimethyl sulfoxide was hardly biodegraded.

[0049]

As described above, according to the present invention, an organic wastewater containing a sulfoxide-type organic sulfur compound is exposed to ultraviolet light in the presence of hydrogen peroxide or ozone, thereby obtaining a sulfoxide-type organic sulfur compound. The compound is decomposed via sulfonic acid to H ₂ O, CO ₂ , and H ₂ SO _4, and can be treated without generating an offensive odor.

Further, after sulfonic acid is produced by a photodecomposition reaction of sulfoxides, it is decomposed under aerobic conditions in a biological treatment, whereby H ₂ O, CO ₂ , It can be decomposed to H ₂ SO ₄ .

[Brief description of the drawings]

FIG. 1 is a flowchart showing an ultraviolet decomposition treatment of a sulfoxide-containing wastewater in Example 1 of the present invention.

FIG. 2 is a graph showing a change in the concentration of each component in UV decomposition of wastewater containing DMSO in Example 1 of the present invention.

FIG. 3 is a flowchart showing a treatment method in which the ultraviolet decomposition treatment and the biological treatment are combined in the sulfoxide-containing wastewater in Example 2 of the present invention.

FIG. 4 is a flowchart showing the ultraviolet decomposition treatment of a sulfoxide-containing wastewater in Example 3 of the present invention.

FIG. 5 is a schematic diagram of an apparatus for ultraviolet ray decomposition treatment of sulfoxide-containing wastewater in Example 3 of the present invention.

FIG. 6 is a graph showing a change in the concentration of each component in UV decomposition of wastewater containing DMSO in Example 3 of the present invention.

FIG. 7 is a flowchart showing a treatment method in which the ultraviolet decomposition treatment and the biological treatment are combined in the sulfoxide-containing wastewater in Example 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultraviolet irradiation device 2 Power supply for low pressure mercury lamp 3 Low pressure mercury lamp 4 Quartz ultraviolet ray reaction tank 5 Ozone treatment tank 6 Diffusion ball for ozone injection 7 Dimethyl sulfoxide containing wastewater 8 Air pump 9 Ozone generator 10 Ozone containing gas 11 Liquid sending pump

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C02F 1/58 C02F 1/32 C02F 1/72 101 C02F 1/78 C02F 3/02

Claims (7)

(57) [Claims] 1. Sulfoxides characterized in that hydrogen peroxide is allowed to coexist in an organic wastewater containing an organic sulfur compound of a sulfoxide, and the organic wastewater is irradiated with a light beam for photoreaction to decompose the organic sulfur compound of the sulfoxide. Wastewater treatment method. 2. The decomposition of the organic sulfur compound of the sulfoxides generates a hydroxyl radical by a photoreaction, and reacts the hydroxyl radical with a carbon-sulfur bond dissociated portion of the sulfoxide to generate sulfonic acids. 2. The method for treating sulfoxide-containing wastewater according to claim 1, wherein the wastewater is decomposed into sulfuric acid by a photoreaction and completely mineralized. 3. Sulfoxide-containing wastewater characterized in that ozone is dissolved in organic wastewater containing a sulfoxide-type organic sulfur compound, and the organic wastewater is irradiated with a light beam for photoreaction to decompose the sulfoxide-type organic sulfur compound. Processing method. 4. The decomposition of the organic sulfur compound of the sulfoxides generates active oxygen by a photoreaction of ozone, and reacts the active oxygen with a dissociated portion of a carbon-sulfur bond of the sulfoxide to generate sulfonic acids. 4. The method for treating sulfoxide-containing wastewater according to claim 3, wherein the sulfonic acid is decomposed into sulfuric acid by a photoreaction, and the mineralization treatment is performed completely. 5. The decomposition of the organic sulfur compound of sulfoxides comprises decomposing the organic sulfur compound of sulfoxides to the form of sulfonic acid, and then decomposing under aerobic conditions in biological treatment, and completely demineralizing. The method for treating sulfoxides-containing wastewater according to claim 1 or 3, wherein 6. The sulfoxide according to claim 1, wherein the light beam for photoreaction has a wavelength having an energy higher than a binding energy of a carbon-sulfur bond of an organic sulfur compound of sulfoxides. Of wastewater containing wastes. 7. The method for treating sulfoxide-containing wastewater according to claim 1, wherein the light beam for photoreaction is ultraviolet light.