JP2534183B2 - Method of removing COD component in water - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to tap water, irrigation water, sewage,
The present invention relates to a method for removing COD components contained in sewage such as human waste, industrial wastewater, natural water and the like.

[0002]

2. Description of the Related Art It is widely known that the conventional ozone treatment method is extremely effective for decolorization, but little effective for removing COD components. For this reason, for example, ozone treatment is used to remove the yellow chromaticity in the activated sludge-treated water of human waste, but since ozone treatment is not effective to remove COD components, activated carbon adsorption is used. In order to release the biologically treated water of human waste into the public waters, it is necessary to lower the COD than the chromaticity, and thus the ozone treatment has been hardly adopted in recent years. However, the use of the activated carbon adsorption method for removing the COD component requires a regeneration treatment of the activated carbon, resulting in a high running cost and complicated maintenance.

On the other hand, if COD can be highly removed by the ozone treatment, it can be said that this is an epoch-making COD removal method because a complicated treatment such as regeneration of activated carbon is not required. However, in the conventional ozone treatment method, when ozone is blown into the ozone contact tank, the efficiency of dissolution of ozone in the treatment liquid is poor, and therefore COD cannot be removed efficiently, and part of the blown ozone is discharged without being consumed. Therefore, there is a drawback that a device for removing exhaust ozone is required.

In order to improve the drawbacks of the conventional ozone treatment method, the inventor of the present invention discloses in Japanese Patent Application No. 3-238109, at least a part of which is made of granular activated carbon which is provided by being immersed in water. COD treatment method in which water to be treated is supplied to a treatment tank having a packed bed while ozone is directly diffused from the bottom of the packed bed and the treated water is passed through the packed bed and the COD
A processing device suitable for processing was proposed. The feature of this ozone treatment method is that when ozone is blown into the water to be treated in the presence of granular activated carbon, the efficiency of dissolution of ozone in the water to be treated becomes high, and the coexistence of the granular activated carbon makes it difficult to dissolve C in the water to be treated.
This means that the oxidation of OD is promoted, and the amount of exhaust ozone discharged without being consumed is also reduced, so that a device for removing exhaust ozone is not required.

However, since there is no means for treating the COD oxidation product after ozone treatment, the COD oxidation product will be measured as BOD when the amount of the hardly soluble COD contained is large. There is a possibility that treated water having an increased BOD value will be discharged by the above-mentioned device alone. Further, in this case, since the amount of ozone blown in is also large, the amount of exhausted ozone is large, and there is a possibility that a device for removing the exhausted ozone is also required.

COD by another conventional ozone treatment method
As a removal method, the treated water is first subjected to ozone treatment, and then the treatment of biofilm is carried out by passing the ozone treated water through the immersion fixed bed containing the biofilm to form one set of treatments. An ozone treatment method in which treatment is repeated has been proposed. For example, the present inventor has filed Japanese Patent Application No. 3-24933.
No. 1 specification describes a COD removal treatment by an ozone treatment method in which water to be treated is passed through an apparatus in which a set of several apparatuses each consisting of an ozone oxidation treatment tank and a biofilm treatment tank are installed in series. A device for that purpose was proposed. In addition, Japanese Patent Application No. 3-293
Japanese Patent No. 883 proposes an ozone treatment method in which water to be treated is circulated through an apparatus comprising an ozone oxidation treatment tank and a biofilm treatment tank to repeat the above-described set of treatments, and an apparatus therefor.

The feature of the ozone oxidation treatment method in which one set of treatments of ozone treatment and biofilm treatment is repeated on the water to be treated in the above two examples is two times as compared with the case where one set of treatment is performed once. In the case of carrying out the above, the COD in which the poorly soluble COD is ozone-oxidized to become a biofilm-processable BOD, which is biologically processed in the next step and eventually COD is removed,
The removal efficiency is extremely improved.

The reason why the COD removal efficiency is remarkably improved when the water to be treated is treated twice or more as compared with the case where the ozone treatment and the biofilm treatment are performed once is due to the following mechanism. Conceivable. That is, when the poorly soluble COD is ozone-oxidized, a part thereof becomes a biofilm-processable BOD, which is bioprocessed in the next step. However, the processing efficiency of the first processing is not sufficiently good. However, it is considered that the poorly soluble COD component that was not converted to BOD in the primary treatment is also subjected to some biological treatment, and the slightly soluble COD component that had been subjected to some biological treatment was treated as the primary treatment in the second and subsequent ozone oxidation treatments. It is a mechanism in which BOD is formed much better than the case, and then BOD components are removed by biological treatment. However, this mechanism is not yet well established.

The above-mentioned Japanese Patent Application Nos. 3-249331 and 3-
In the ozone treatment method described in 293883 specification, since ozone is not blown in the presence of activated carbon as in Japanese Patent Application No. 3-238109, the dissolution efficiency of ozone in water to be treated is not high, Therefore, an exhaust ozone treatment device is required. In addition, circulating the water to be treated in a two-step treatment apparatus for ozone treatment and biological treatment, or arranging a plurality of apparatuses in series has a drawback that the apparatus becomes large and complicated.

[0010]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned drawbacks of the prior art. Specifically, the efficiency of ozone dissolution in water to be treated is improved, and the COD component is highly efficient. An object of the present invention is to provide an ozone treatment method that decomposes and does not require an exhaust ozone treatment device.

[0011]

SUMMARY OF THE INVENTION The above object of the present invention is described below
Method and apparatus. (1) at least a portion is immersed in water, o from below
Water to be treated from above in a packed bed of activated carbon with aeration
After conducting the ozone treatment of the water to be treated by downward flow, the outflow water of the packed bed was further provided below the packed bed.
The air from below to the packed bed of activated carbon
A method for removing COD components in water, which comprises biological treatment by an aerobic biofilm method . (2) Activated carbon packed bed below the activated carbon packed bed A in the device
B is provided, and an ozone supply pipe and ozone are provided below the packed bed A.
An air diffuser is provided, and an oxygen-containing supply pipe and an oxygen-containing supply pipe are provided below the packed bed B.
An oxygen diffuser is installed, and the treated water supply pipe is on the upper end of the device.
C, characterized in that each of the treated water is provided with an outlet pipe
OD removal device.

A feature of the present invention is that a granular activated carbon packed bed is used as an ozone contact tank for ozone treatment of water to be treated containing COD, and an ozone-containing gas is diffused into the packed bed. The effluent water from the step of the preceding paragraph is passed through a packed bed of a filter medium having microorganisms carried on the surface of granular activated carbon or the like for biological filtration treatment. It is in.

In the present invention, ozone is usually supplied in the form of an ozone-containing gas, but its composition can be set arbitrarily. Further, the water to be treated containing COD may be passed through a packed bed filled with granular activated carbon or the like in a downward flow or an upward flow.

As described above, by treating the water to be treated containing COD with ozone in the presence of activated carbon, not only the COD component can be oxidized with high efficiency, but also the biodegradability of the COD component is improved. It is possible to let In addition, since the COD component can be oxidized with high efficiency, the effect of reducing the amount of exhaust ozone is expected, and therefore the exhaust ozone treatment device becomes unnecessary.

As the activated carbon used in the present invention, granular or fibrous activated carbon is advantageous because it has a low water resistance, and coal type, coconut husk type, coal pitch type or the like can be used.

As the carrier used for the biofilm method, known carriers such as anthracite, chamotte, anti-firestone, and other granular minerals and human bone lightweight porous aggregate can be used, but they have a wide attachment area for organisms. It is desirable to use activated carbon. In the present invention, the COD contained in the water to be treated is highly efficiently oxidized and removed, so that the adsorption of the COD component by the activated carbon becomes unnecessary, so that the activated carbon of the activated carbon packed bed (filled bed A) in the ozone treatment section is not required. No operation is required to replay. Similarly, the operation of regenerating the activated carbon of the carrier of the activated carbon layer used for the biofilm method (referred to as the packed bed B) is also unnecessary. The activated carbon in the activated carbon packed bed A of the ozone treatment section is gradually consumed due to the reaction with ozone, so it is necessary to periodically replenish the consumed amount. Further, since the packed bed A and the packed bed B are clogged due to the SS contained in the water to be treated and the proliferating microorganisms, it is necessary to appropriately wash them.

(Operation) The operation of the present invention will be described with reference to FIG. However, the present invention is not limited to the specific examples described below. The COD removing apparatus 1 of the present invention comprises a packed bed A of granular or fibrous activated carbon, an ozone diffuser 2 and a packed bed B of granular or fibrous activated carbon. In FIG. 1, the water to be treated is supplied to the removing device 1 in a downward flow, but it may be an upward flow, and a removing device in which a packed bed A for ozone treatment and a packed bed B for biological treatment are integrated. However, the treatment tank having the packed bed A and the treatment tank having the packed bed B may be arranged in series in two tanks. Further, the packed bed A of activated carbon is completely immersed in the water to be treated, but a part of the packed bed may be exposed on the water surface.

The COD-containing treated water supplied from the treated water supply pipe 3 is ozone-oxidized in the packed bed A and then the packed bed B.
After being subjected to biological filtration with COD, COD is removed and the treated water flows out of the system from the treated water outflow pipe 4.

The ozone-containing gas diffuses from the ozone supply pipe 5 through the diffuser pipe 2 into the removing device 1 from the lower part of the packed bed A,
The bubbles enter the activated carbon packed bed A and COD in the water to be treated is ozone-oxidized in the packed bed A. As already described above, ozone treatment of the water to be treated in the presence of activated carbon can not only efficiently oxidize the COD component but also improve the biodegradability of the COD component. That is, the COD component in the water to be treated is changed to a BOD component that can be biologically treated. This is a feature of the present invention.

The ozone-oxidized water is then sent to the packed bed B. The surface of the packed bed B is filled with granular activated carbon in which microorganisms are propagated, and an oxygen-containing gas such as air is supplied from the gas supply pipe 6 to the diffuser pipe 7 installed at the lower part of the packed bed B to form a diffuser pipe. Blown into layer B from 7. In the process of the ozone-oxidized water passing through the packed bed B, biologically treatable BOD components and the like are biologically treated and removed. The biologically treated water flows out of the system through a treated water outflow pipe 4 provided at the bottom of the COD removing device 1.

As described above, in the present invention, the COD-containing water to be treated is ozone-oxidized in the presence of activated carbon, and therefore the COD removal rate is higher than that of simply ozone-oxidized without the presence of activated carbon. Activated carbon does not adsorb COD components,
Since it catalyzes ozone oxidation and the catalytic activity of these activated carbons does not easily deteriorate, the activated carbon does not need to be regenerated. However, during the ozone oxidation treatment, these activated carbons are gradually consumed by the reaction with ozone, so that it is necessary to supplement the activated carbons, but the activated carbons can be used. Further, the feature of the present invention is that it is not necessary to treat the exhaust ozone.

The cause of the above-mentioned various effects is not clear yet, but it is estimated as follows. That is, when activated carbon is present in the process of ozone-oxidizing COD-containing water to be treated, the catalytic action of activated carbon produces free radical active oxygen species in the ozone-containing gas, which strongly oxidize the COD component and cause inferior organisms. Converts degradable COD into highly biodegradable components. It is considered that a series of actions of this component being decomposed into CO ₂ and H ₂ O by the biofilm treatment are occurring.

[0023]

EXAMPLES The purification treatment method of the present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

Example 1 Human urine was subjected to nitrification denitrification treatment without dilution, and the treated water was subjected to coagulation and precipitation treatment with FeCl ₃ and then sand-filtered (COD 57 mg / liter, chromaticity of 80 ° and yellowed). Which is the treated water of the present invention. In addition, COD (57 m
(g / l) is a non-biodegradable COD component, which conventionally had to be removed by activated carbon adsorption.

The COD removal process of the present invention was performed using the apparatus having the structure shown in FIG. The specifications of the device are as shown in Table 1. Table 1 Specifications of COD removal device Device dimensions Diameter: 100 mmφ (cylindrical column) Height: 3500 mm Height of packed bed A: 1000 mm Height of packed bed B: 1500 mm Filter medium of packed bed A: COD has already reached saturated adsorption Granular activated carbon (coal-based 2-3 mm) Filter material of packed bed A: Same as above Flow rate of superficial water in column: 50 m / day Ozone injection rate load: 400 mg / liter Air supply amount: 3 times amount of treated water flow amount

After continuous treatment for 3 months under the conditions shown in Table 1, after confirming that the packed bed B was sufficiently collected with microorganisms,
Water quality analysis was performed once a day from the second month. As a result, Table A
The average water quality as shown in was obtained.

[0027]

[Table 1]

The ozone concentration in the exhaust gas was 1 mg / liter or less.

(Comparative Example 1) Comparative processing was carried out in parallel under the same processing conditions as in the above example except that the filling layer A was removed. As a result, the average water quality as shown in Table B was obtained.

[0030]

[Table 2]

The ozone concentration in the exhaust gas is 10 mg /
It was liter.

From the comparison between Table A and Table B, the COD of the present invention
It is clear that the removal effect is high. Further, the results of the comparative treatment under the same conditions except that the packed bed B was removed are clear from the results of the packed bed A outflow water in Table A.

[0033]

【The invention's effect】

(1) The effect of removing non-biodegradable COD is high. (2) The exhaust ozone concentration decreases. (3) Regeneration of activated carbon is not required. (4) COD can be removed at a high removal rate without requiring an activated carbon adsorption step.

[Brief description of drawings]

FIG. 1 is a process flow diagram illustrating a method for removing a COD component according to the present invention.

[Explanation of symbols]

 1 COD removal device 2 Ozone diffuser pipe 3 Treated water supply pipe 4 Treated water outflow pipe 5 Ozone supply pipe 6 Gas supply pipe 7 Diffuser pipe A Packing layer B Packing layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C02F 3/06 C02F 3/06 3/10 3/10 A

Claims (2)

(57) [Claims] 1. A were immersed at least partially water, thereunder
From the other side, the water to be treated is placed in an activated carbon packed bed with ozone diffused.
After conducting the ozone treatment of the water to be treated by guiding it downward from above, the outflow water of the packed bed is further installed below the packed bed.
In the packed bed of activated carbon with air diffused from below.
A method for removing COD components in water, which comprises flowing down and performing biological treatment by an aerobic biofilm method. 2. The activated carbon is placed below the activated carbon packed bed A in the apparatus.
A charcoal packed bed B is provided, and an ozone supply pipe and
And an ozone diffusing pipe are provided, and oxygen-containing supply is provided below the packed bed B.
A pipe and an oxygen-containing air diffuser are installed, and treated water is supplied to the upper end of the device.
Characterized by each treated water outlet pipe being installed at the bottom end
COD removal device.