JP2012213764A - Decoloring cleaning method and decoloring cleaning apparatus of organic colored wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decoloring cleaning method of contaminated waste water, by which decoloring of contaminated waste water including colored organic substances and oxidative decomposition reaction of contaminants can be very efficiently carried out.SOLUTION: Air-containing gas is blown in the contaminated waste water including the colored organic substances and the waste water in a gas liquid mixing state is made to pass through a reaction tower filled with a carbonaceous material on which a microorganism film is formed. Then electrolytic functional water which is obtained by electrolysis of electrolyte aqueous solution including chloride ions by using an iridium oxide-containing electrode as an anode, is added to cause reaction and then the water is made to pass through a catalytic reaction tower filled with an organic porous material including iron oxide at the subsequent stage.

Description

  The present invention relates to a method for purifying polluted colored wastewater mainly composed of organic matter. More specifically, the present invention relates to a method for purifying polluted colored wastewater that can decompose coloring organic matter in polluted water to reduce the degree of coloration and concentration of the polluted water and suppress the generation of unpleasant odor generated from the polluted water. . Specific wastewater that is subject to application includes wastewater discharged from the laver processing production process. This waste water contains organic suspended solids such as laver, and is colored red to reddish brown. The present invention relates to a method for purifying such suspension colored waste water.

Conventionally, a coagulation sedimentation method, a biochemical treatment method, an activated carbon adsorption treatment method, and the like have been put to practical use as a purification method for wastewater containing general coloring organic substances. In addition, a decoloring method using an oxidizing agent such as sodium hypochlorite or ozone has been put into practical use.
Furthermore, a method of treating functional water produced by electrolysis of water containing electrolyte with a colored solution under light irradiation (Patent Document 1) or coloring a reaction tank filled with sulfur or a mixture of sulfur and calcium carbonate The effectiveness of a method for introducing decolored water by introducing decolorized water (Patent Document 2) and a method for decolorizing by directly electrolyzing contaminated water (Non-Patent Documents 1 and 2) have been reported.
In addition, as a method for removing pollutant components from wastewater discharged when producing laver, a method is also proposed in which an aeration process for supplying oxygen under conditions in which koji molds are added after precipitation of suspended substances has been proposed. (Patent Document 3).

JP 2000-79386 “Coloring solution processing method and coloring solution processing apparatus” JP2003-103280 "Method and apparatus for decolorizing wastewater" JP 2005-254040 "Drainage treatment method for seaweed"

Journal of Japan Society on Water Environment, 22 (6), 498-504 (1999): “Decolorization of molasses waste using electrolysis” Journal of Japan Society on Water Environment, 22 (11), 938 (1999): “Electrolytic treatment of persistent organic substances in lake water”

In the coagulation sedimentation method, coagulated sludge is generated along with the treatment, and thus there is a problem that requires disposal. The activated sludge method, which is the most commonly used biological treatment method, is a method that utilizes the proliferation reaction of floating cells. This method has a problem that surplus sludge is generated along with the growth reaction of the bacterial cells, and its disposal is required.

In addition, since biochemical treatment has a slow reaction rate, it is necessary to increase the residence time. Therefore, there is also a problem that the reaction tank capacity must be increased.

Oxidation methods using oxidizing agents such as sodium hypochlorite and ozone have a faster reaction rate than biochemical treatment methods, but oxidants remaining in the treated water live in the discharge water area of the treated water. It is necessary to decompose and remove residual oxidizing substances prior to release, since they may adversely affect living organisms and may be killed in some cases.

The method of treating functional water produced by electrolysis of water containing electrolytes with a colored solution under light irradiation (Patent Document 1) has a limit in the depth of penetration of the irradiated light into the solution, and a large amount of wastewater In order to improve the contact efficiency between light and drainage, it is necessary to provide a device structure having a large light receiving area, and there is a problem that a large installation area is required.

A method of decolorizing treatment by introducing colored water into a reaction tank filled with sulfur or a mixture of sulfur and calcium carbonate (Patent Document 2) is a method using sulfur-oxidizing bacteria. It is necessary to blow in air and control to appropriate conditions.

In the method of aeration treatment under the condition that a predetermined amount of koji mold is added to laver drainage, it is necessary to prepare a specific koji mold corresponding to the amount of drainage.

 The present invention provides a novel method for treating organic colored polluted water discharged from a seaweed processing production process that is simpler in operation management than the conventional colored polluted water treatment method as described above and has excellent decolorization and purification treatment effects. It is to provide.

In order to solve the above problems, the method for purifying organic colored wastewater containing suspended solids of the present invention blows a predetermined amount of air (gas containing oxygen) into organic colored polluted wastewater discharged from the laver processing production process. After passing through a granular bamboo charcoal packed tower in a gas-liquid mixed state, treated water (electrolytic functional water) electrolyzed with chloride-containing water using an iridium oxide-containing electrode as an anode is added for a predetermined time. By reacting and then contacting with iron oxide-carrying bamboo charcoal, which is a porous material containing iron oxide, the decomposition reaction of the pollutant by the oxidizing active substance in the electrolytic functional water is promoted, and at the same time, the excessive residual oxidizing substance is decomposed and removed. By doing so, the colored polluted water is purified with high efficiency.

According to this method, the decolorization of organic colored polluted water discharged from the seaweed processing production process and the oxidative decomposition reaction of polluted substances proceed very efficiently, and the polluted water can be purified. As a result, TOC (total organic carbon), COD (chemical oxygen demand), BOD (biochemical oxygen demand), coloration (absorbance), and turbidity can be reduced. At the same time, nitrogen and phosphorus concentrations can be reduced. In addition, since phosphorus is not only removed but also captured on the iron oxide-carrying bamboo charcoal surface, it can be reused as fertilizer. Furthermore, the dissolved oxygen concentration in the wastewater also increases, so the habitat of fish and shellfish in the target water area can be improved.

1 is a view for explaining a first embodiment of a processing apparatus according to the present invention. 2 is a view for explaining a second embodiment of the processing apparatus according to the present invention.

The basic treatment process of the wastewater treatment method in the present invention is shown in FIG.
Hereinafter, an embodiment of the present invention will be described with reference to FIG.
The air blowing 2 into the colored polluted water is either a method of introducing a predetermined amount of air into the colored polluted water flow path into the biological reaction tower 3 filled with granular charcoal (bamboo charcoal) in a gas-liquid mixed state, or the colored polluted water Either method may be used, in which liquid is passed through the granular charcoal (bamboo charcoal) packed biological reaction tower 3 and air is separately blown from the lower part of the granular charcoal biological reaction tower 3, and can be selected according to the situation.
Note that the amount of air to be blown varies depending on the pollution state of the target colored polluted waste water 1. Accordingly, since the required air amount varies depending on the target decolorization rate and organic matter removal rate, the air blowing amount may be adjusted in consideration of the water quality of the target polluted wastewater.

The upward flow type electrolytic reaction cell 8 uses an iridium oxide electrode for the anode 6. As a base material for the iridium oxide electrode, a titanium material having an arbitrary thickness can be used, and a surface of which a iridium oxide thin film is coated to a thickness of 0.5 to 5 μm can be used. The thickness of the iridium oxide thin film may be 0.5 μm or more, but 1 to 5 μm is suitable in consideration of wear during long-term use. However, if it is allowed to increase the manufacturing cost, there is no problem in performance even if it is 5 μm or more.

As the aqueous electrolyte solution 5, an aqueous electrolyte solution containing chloride ions is used. Specifically, seawater containing chloride ions can be used. In a place where seawater is difficult to obtain, an aqueous solution in which sodium chloride is dissolved at a predetermined concentration can be used. The salt concentration in these aqueous solutions may be in the range of 0.5 to 5% by weight, but considering the current efficiency, the range of 1 to 3% by weight is practical.

The condition for passing the electrolyte aqueous solution 4 through the electrolytic reaction tank 5 is an upward flow. High flow rate conditions are desirable. When the flow rate is slow, the time that the gas generated by the electrolytic reaction stays in the electrolytic reaction tank becomes longer, and the current resistance between both electrodes is increased to increase the voltage between the electrodes and increase the power consumption. .

Iron oxide-carrying bamboo charcoal, which promotes the oxidation reaction of organic pollutants by oxidative active substances in electrolyzed functional water 9, is mainly composed of iron oxide on the pore surface of porous carbon material obtained by carbonizing bamboo, which is an organic porous material. It is effective to use a functional material carrying 0.05 to 20% by weight of a metal oxide, which is an important feature of this treatment method.

The above-mentioned contact treatment method of the functional material and polluted water can achieve its purpose by passing water through a reaction tower packed with a granular functional material.

<Example 1>

Internal diameter 30 mm, height 500 mm, and 300 cm ³ filled with the granular charcoal in a glass column of capacity 350 cm ³ (packing height: 425 mm) was reactor. The colored polluted wastewater discharged from the laver processing production process is passed upward through the reaction tower at a flow rate of 300 cm ³ / h, and at the same time, air is continuously blown from the bottom of the reaction tower at a flow rate of 3,000 cm ³ / h. The experiment was conducted.
After gas-liquid separation in the upper part of the reaction tower, the effluent was received in a stirred reaction tank using a 500 cm ³ volume beaker, and electrolysis functional water produced by electrolyzing water containing chloride ions in the reaction tank was 30 cm. It was made to react by the method of adding ³ / h granular continuously.
For the production of functional electrolytic water, a 3% by weight sodium chloride aqueous solution is used as the aqueous electrolyte solution, an iridium oxide electrode of 50 mm x 50 mm x 3 mm is used for the anode, and SUS316L with the same shape as the anode is used for the cathode. Was carried out using an upward flow type electrolytic reaction cell set to have an interval of 5 mm. Electrolyzed functional water was produced by a method in which an electrolytic aqueous solution was passed in a transient manner under the condition that a direct current of 0.62 A was passed through the electrolytic reaction cell.
The liquid holding amount in the reaction tank is 330 cm ³ (residence time is 1 h), the processing liquid flowing out from the reaction tank is received in the storage tank, and the liquid in the storage tank is filled with 150 cm ³ of granular catalyst at a flow rate of 330 cm ³ / h. The catalyst reaction tower was continuously passed through. Table 1 shows the results of water quality analysis for each treatment process 5 hours after the start of liquid flow.

From the results in Table 1, when comparing the quality of raw water (polluted water) and treated water for each treatment step, the absorbance decreased from 0.246 to 0.083 at the biological reaction tower outlet, and became 0.002 for the catalytic reaction tower treated water to become transparent. I was able to decolorize
The TOC value decreased to 151 mg / L at the biological reaction tower outlet to 87.6 mg / L, and to 7.4 mg / L for the catalytic reaction tower treated water.
The TN value is 27.9 mg / L for raw water, but it is 15.7 mg / L at the outlet of the biological reaction tower and 0.8 mg / L for the catalytic reaction tower treated water.
The residual chlorine concentration was not detected in the raw water, but it was detected at 1,430 mg / L after the addition of electrolytic functional water to the biological activated carbon treated water. However, it falls below the detection limit (ND) at the outlet of the catalytic reaction tower. It turns out that the residual chlorine removal effect of the used catalyst is excellent.
Looking at the phosphorus concentration, raw water shows a value of 9.7 mg / L, but the biological reaction tower outlet is 8.2 mg / L, and the catalytic reaction tower treated water is down to 0.61 mg / L.
As these results show, it was confirmed that the colored polluted water can be decolorized and purified by the treatment method of the present invention.

<Comparative Example 1>

A continuous experiment was conducted under the same conditions as in Example 1 except that air was not blown into the biological reaction tower in Example 1. Table 2 shows the water quality of each treatment process water when it is almost in a steady state.

From the results in Table 2, comparing the quality of raw water (polluted water) and treated water for each treatment step, the absorbance decreased from 0.246 to 0.167 at the biological reaction tower outlet and 0.012 for the catalytic reaction tower treated water.
The TOC value was 151 mg / L at the biological reaction tower outlet, 133 mg / L, and the catalytic reaction tower treated water was 24 mg / L.
The TN value was 22.1 mg / L for raw water, 22.1 mg / L at the outlet of the biological reaction tower, and 1.3 mg / L for the catalytic reaction tower treated water.
Looking at the phosphorus concentration, the raw water showed a value of 9.7 mg / L, but the biological reaction tower outlet was 9.6 mg / L, and the catalytic reaction tower treated water was 0.63.
Reduced to mg / L.
As for residual chlorine concentration, 1,440 mg / L was detected after the addition of electrolyzed functional water to biological activated carbon-treated water, and it dropped below the detection limit at the catalytic reaction tower outlet. Compared to the examples, the examples show 99% or higher removal performance of the absorbance decrease rate, and TOC, TN, and P removal rates of 95%, 97%, and 94%, respectively. On the other hand, in this comparative example, the air was not blown into the biological reaction tower, but the TOC removal effect in the biological reaction tower was reduced, resulting in the removal rate of TOC up to the catalyst-treated water. Decreased from 95% of the examples to 84%.

<Comparative example 2>

Experiments were performed under exactly the same conditions as in Example 1 except that the filler in the biological reaction tower used in Example 1 was changed to granular charcoal and glass beads having an average particle diameter of 3 mm were packed. Table 3 shows the results of water quality analysis for each treatment process.

From the results in Table 3, comparing the quality of raw water (polluted water) and treated water for each treatment step, the absorbance decreased from 0.246 to 0.182 at the glass bead outlet, and became 0.022 in the catalytic reaction tower treated water, and it was decolorized to transparency. did it
The TOC value decreased to 151 mg / L at the outlet of glass beads and 147 mg / L at the outlet of the glass beads, and to 52 mg / L at the water treated in the catalytic reaction tower.
The TN value is 27.9 mg / L for raw water, but it is 26.8 mg / L at the glass bead outlet and 2.1 mg / L for the catalytic reaction tower treated water.
The residual chlorine concentration was not detected in the raw water, but it was detected at 1,450 mg / L after the electrolytic functional water was added to the treated water blown into the glass bead packed tower. However, it falls below the detection limit at the catalyst reaction tower outlet. It turns out that the residual chlorine removal effect of the used catalyst is excellent.
Looking at the phosphorus concentration, the raw water shows a value of 9.7 mg / L, but the catalytic reaction tower treated water has dropped to 0.64 mg / L.

<Comparative Example 3>

Experiments were carried out by adding the electrolyzed functional water directly to the polluted raw water under the condition that the biological reaction tower was not installed in the first embodiment. The production conditions for the electrolyzed functional water were the same as in the examples. Table 4 shows the water quality analysis results for each treatment process.

From the results in Table 4, comparing the quality of raw water (contaminated water) and the quality of treated water in each treatment step, the absorbance was 0.246 and 0.049 was obtained in the catalytic reaction tower treated water, and it was possible to decolorize to transparency.
The value of TOC decreased to 151 mg / L after addition of functional water to 151 mg / L, and to 64 mg / L for the catalytic reaction tower treated water.
The TN value is 27.9 mg / L for raw water, but it is lowered to 2.2 mg / L for water treated in the catalytic reaction tower.
Residual chlorine concentration was not detected in raw water, but 1,450 mg / L was detected after the addition of electrolytic water. However, it falls below the detection limit at the catalyst reaction tower outlet. It turns out that the residual chlorine removal effect of the used catalyst is excellent.
Looking at the phosphorus concentration, the raw water shows a value of 9.7 mg / L, but the catalytic reaction tower treated water has dropped to 0.64 mg / L.

The present invention has been developed for the purpose of decolorizing and purifying colored waste water as a decolorizing and purifying treatment method for laver processing production wastewater, but is not limited to this field, and waste water treatment method that discharges organic polluted water. Can be used widely. As specific application fields, it can be applied to the treatment of livestock wastewater, the treatment of dyeing wastewater, the treatment of wastewater containing organic coloring substances in the chemical industry, and the like.

1. 1. Colored contaminated water Air 3. 3. Single-stage granular charcoal (bamboo charcoal) packed biological reaction tower Exhaust gas 5. 5. Electrolyte aqueous solution Anode 7. Cathode 8. 8. Upflow type electrolytic reaction cell Electrolytic functional water
10. Chemical oxidative decomposition reactor
11. Metal-supported bamboo charcoal catalytic reactor
12． Treated water
13. Multistage granular charcoal (bamboo charcoal) packed reaction tower

Claims (6)

A method for treating polluted wastewater, which comprises biochemically treating polluted wastewater containing organic matter, adding water containing an oxidizing active substance, and passing the treated water through a catalyst packed bed.
A gas containing oxygen is blown into a reaction tower filled with a particulate material in which a microbial film is formed on the surface of the pores of a carbon material having a pore volume of 40 to 85% by volume. 2. The method for purifying polluted water according to claim 1, wherein a colored polluted wastewater containing water is passed through.
Water containing an oxidative active substance is passed through an up-flow type electrolytic reaction cell using an electrode containing iridium oxide as an anode, and water containing chloride ions is passed through and electrolyzed under a current density of 100 to 3,000 A / m ^2. 3. The method for purifying polluted water according to claim 1 or 2, wherein the treated water (electrolyzed functional water) is treated water.
The catalyst packed in the catalyst packed tower is converted to a granular carbon material under the condition of 0.2 to 10% by weight of iron oxide on the pore surface of a granular carbon material having a porous structure with a pore volume of the carbon material of 40 to 85% by volume. 4. The method for purifying polluted water according to claim 1, 2 and 3 characterized by being carried.
In the apparatus for treating polluted wastewater containing organic matter according to claim 1, claim 2, claim 3 and claim 4, a biological reaction filled with granular charcoal having a microbial film formed on the surface of the pores of the carbon material An apparatus for purifying polluted water, comprising a tower, an upward flow type electrolytic reaction cell using an electrode containing iridium oxide for generating an oxidation active substance as an anode, and a metal-supported bamboo charcoal catalyst reaction tower.
6. The apparatus for purifying polluted water according to claim 5, wherein the biological reaction tower filled with granular charcoal for biochemical treatment has a reaction tower structure divided into a plurality of sections.