JP2001104996A - Water treatment method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain treated water of high quality by efficiently treating organic matter contained in water to be treated. SOLUTION: A water treatment apparatus is equipped with a biological treatment apparatus 1 for treating water L1 to be treated containing organic matter by using microorganisms to form biologically treated water L2, a solid- liquid separation treatment apparatus 2 for separating the biologically treated water L2 into a solid S1 and a separated liquid L3, a concentration and separation treatment apparatus 3 for concentrating the separated liquid L3 to separate the same into a concentrated liquid L4 with an organic matter concentration of a predetermined value or more and a treated liquid L5 with an organic matter concentration of the predetermined value or less and a chemical oxidation treatment apparatus 4 for chemically oxidizing the organic matter contained in the concentrated liquid L4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating water to be treated containing a biodegradable organic substance and a biodegradable organic substance.

[0002]

2. Description of the Related Art In the industrial waste treatment industry and the semiconductor industry,
BACKGROUND ART Industrial wastewater from various industries, contaminated groundwater, and the like contain organic substances that are not easily decomposed by microorganisms, so-called biodegradable organic substances. Such water (hereinafter referred to as “water to be treated”) is treated as it is discharged into the natural state as it is, because it degrades the environment. As a method for treating the water to be treated containing organic substances,
For example, as disclosed in Japanese Patent Application Laid-Open No. H11-128991 (conventional example 1), a method of subjecting water to be treated to a biological treatment followed by a chemical oxidation treatment,
As disclosed in Japanese Unexamined Patent Application Publication No. 2000-168 (Prior Art 2), there is a method of subjecting water to be treated to a chemical oxidation treatment and then a biological treatment.

[0003]

However, in the conventional example 1, the water to be treated, whose organic matter concentration has been reduced by biological treatment, is sent to the chemical oxidation treatment step. Since the reactivity of the chemical oxidation reaction decreases as the organic matter concentration decreases, the efficiency of the chemical oxidation treatment step after biological treatment is often low. On the other hand, in Conventional Example 2, since all organic substances are loaded in the chemical oxidation treatment step, including harmless organic substances and organic substances that can be rendered harmless by biological treatment, the load of the chemical oxidation treatment step is often high. . In addition, performing complete oxidation in the chemical oxidation process consumes a large amount of energy, and thus, in this method, the water to be treated that has been partially oxidized is loaded into the biological treatment process. Substances may be produced and the biological treatment process may not function properly. Further, there is a possibility that organic substances that should not remain if completely oxidized by the chemical oxidation treatment remain.

The present invention has been made in view of such circumstances, and can efficiently treat biodegradable organic substances and biodegradable organic substances contained in water to be treated such as wastewater. An object of the present invention is to provide a water treatment method and a water treatment apparatus that can obtain a high-quality treated liquid.

[0005]

Means for Solving the Problems To solve the above problems, a water treatment method of the present invention comprises a biological treatment step of treating treated water containing an organic substance with a microorganism to produce a biological treatment liquid; A solid-liquid separation step of separating the biological treatment liquid into a solid content and a separation liquid, and concentrating the separation liquid, and a concentrated liquid having a concentration of an organic substance of a predetermined value or more and a treated liquid of not more than a predetermined value. And a chemical oxidation treatment step of chemically oxidizing organic substances contained in the concentrate.

According to the present invention, in the biological treatment process,
Biodegradable organic substances are decomposed among the organic substances contained in the water to be treated. The separated liquid produced from the biological treatment liquid in the solid-liquid separation treatment step is treated in the concentration separation treatment step mainly with a concentrated liquid containing a large amount of organic substances that are hardly biodegradable and containing little or no organic matter. Separated from the liquid. Then, in the chemical oxidation treatment step, the concentrate is efficiently decomposed while maintaining high reactivity. In this way, the biological treatment liquid obtained by biodegrading the water to be treated is converted into a high-concentration liquid mainly containing a biodegradable organic substance in the concentration separation treatment step. Therefore, the chemical oxidation treatment performed in the subsequent stage is efficiently performed while maintaining high reactivity. In addition, by performing the biological treatment first, the biodegradable organic substance is not supplied to the chemical oxidation treatment step, so that the possibility of generating an inhibitory substance is reduced, and the treatment can be performed efficiently.

[0007] In addition, the chemical treatment solution generated in the chemical oxidation treatment step is combined with any one of the water to be treated, the separated solution, and the treated solution, so that the treatment is efficiently performed. That is, although the chemical oxidation treatment takes a long time and has low efficiency, for example, a chemical treatment having a predetermined concentration is generated by performing the chemical oxidation for a predetermined time, and the chemical treatment is returned to the concentration separation treatment step. By sending to the chemical oxidation treatment step again in a state where the concentration is increased and the reactivity is enhanced, a highly reactive treatment can be performed while suppressing the chemical oxidation treatment time.

[0008] A volatilization step is provided in at least one of the former stage and the latter stage of the biological treatment step, and the gas discharged from the volatilization step is treated in a chemical gas oxidation treatment step provided separately from the chemical oxidation treatment step. Thereby, for example, even when the organic matter contained in the water to be treated has volatility, the organic matter is surely treated. At this time,
The volatilization step can also be changed by making the microorganisms in the biological treatment step aerobic.

In such a water treatment method, a biological treatment apparatus for producing a biological treatment liquid by treating water to be treated containing an organic substance with a microorganism, and separating the biological treatment liquid into a solid content and a separated liquid. A solid-liquid separation treatment device, a concentration separation treatment device for concentrating the separated liquid, and separating into a concentrated liquid having a concentration of an organic substance equal to or more than a predetermined value and a treated liquid having a concentration equal to or less than a predetermined value; And a chemical oxidation treatment device for chemically oxidizing the organic matter to be produced.

The water treatment apparatus is provided at least one of a stage before and after the biological treatment device, and a volatilizing device for volatilizing the water to be treated or the biological treatment liquid, and a water discharged from the volatilizing device. And a chemical gas oxidation treatment device for chemically oxidizing and decomposing organic substances in the gas.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A water treatment method and a water treatment apparatus according to one embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram showing a first embodiment of the water treatment apparatus of the present invention. In FIG. 1, a water treatment apparatus A treats water to be treated L1 containing an organic substance using a microorganism to produce a biologically treated liquid L1.
Treatment apparatus 1 for producing a liquid 2 and a solid-liquid separation treatment apparatus 2 for separating the biological treatment liquid L2 into a solid content S1 and a separated liquid L3.
And a concentration separation treatment device 3 for concentrating the separated liquid L3 into a concentrated liquid L4 in which the concentration of the organic substance is equal to or higher than a predetermined value and a treated liquid L5 in which the concentration of the organic substance is equal to or lower than the predetermined value. And a chemical oxidation treatment device 4 for performing an oxidation treatment.

The biological treatment apparatus 1 mainly decomposes and removes biodegradable organic substances among the organic substances contained in the treated water L 1, and supplies the treated water L supplied to the tank 12.
1 is treated by the activated sludge method. That is, the biological treatment apparatus 1 stirs the water to be treated L1 while continuously aerating the same with the blower 11 to proliferate various aerobic microorganisms having a high oxidizing ability for organic substances contained in the water to be treated L1, and use the microorganisms. To decompose the biodegradable organic matter in the water to be treated L1. The biodegradable organic matter in the water to be treated L1 is decomposed into carbon dioxide and water by the biotreatment device 1. In the present embodiment, the activated sludge method is used as the biological treatment step. For example, various methods such as a trickling filter method, a nitrification denitrification method, an upflow anaerobic filter method, and a contact aeration method are used. Can be used as appropriate.

The biological treatment liquid L2 generated by the biological treatment device 1 is sent to the solid-liquid separation treatment device 2. Biological treatment liquid L
2 is a partially decomposed organic substance contained in the water to be treated L1 and mainly contains a biodegradable organic substance;
In the solid-liquid separation processing device 2, the solid component S1 is separated into a liquid separated component L3. This solid-liquid separation processing device 2
Is provided with a sedimentation part 14 and a filtration part 15, and the biological treatment liquid L2 is separated into a solid content and a liquid content by the gravity sedimentation method in the sedimentation part 14, and then separated by the high-speed filtration method in the filtration part 15. Is done. The solid content S1 obtained in the sedimentation part 14 stays in the sedimentation part 14 or is returned to the biological treatment apparatus 1 by the sludge return pump 13, and a part of the solid matter S1 is subjected to a drawing process as required. The separation liquid L3 that has passed through the filtration unit 15 is sent to the concentration separation processing device 3 by the pressure pump 16. In the present embodiment, the gravity precipitation method and the high-speed filtration method are used as the solid-liquid separation process, but a slow filtration method and a membrane separation method can also be used.
Further, for example, various methods such as a long hair filtration method, a centrifugal separation method, and a liquid cyclone can be appropriately used.

The separated liquid L3 generated by the solid-liquid separation processing device 2 is sent to the concentration separation processing device 3. The separation liquid L3 contains organic substances that cannot be completely removed in the biological treatment step and the solid-liquid separation treatment step. In this case, the separation liquid L3 mainly contains organic substances that are hardly biodegradable. The concentration separation treatment device 3 includes a reverse osmosis filtration unit 17, and the separated liquid L3 is subjected to reverse osmosis filtration.
It is separated into a concentrated liquid L4 containing a high concentration of the organic substance and a treated liquid L5 containing no or almost no organic substance. The processed liquid L5 is in a state where the organic substance concentration is processed to a predetermined value (target value) or less. As shown in FIG. 2, the reverse osmosis filtration unit 17 includes a casing 21, a reverse osmosis membrane 22, a header 23, a separated liquid inlet 24, and a concentrated liquid outlet 2.
5 and a treated liquid outlet 26. The organic matter in the separated liquid L3 is concentrated by passing through the reverse osmosis filtration unit 17 to become the concentrated liquid L4, and is sent from the concentrated liquid outlet 25 to the chemical oxidation treatment apparatus 4. On the other hand, the processed liquid L5 is taken out from the processed liquid outlet 26. In the present embodiment, a reverse osmosis filtration method is used as the concentration separation treatment step. For example, an adsorbent filtration method, an adsorbent fluidized bed method, an ultrafiltration method, a distillation method, or a combination thereof is used. Can be used as appropriate.

The concentrated liquid L4 generated by the concentration separation processing device 3 is sent to the chemical oxidation treatment device 4. Concentrate L4
Contains a high concentration of organic matter that could not be removed in the biological treatment step, the solid-liquid separation treatment step, and the concentration separation treatment step, and in this case, mainly contains a biodegradable organic matter. The chemical oxidation treatment device 4 includes a tank 18 and an ozone generator 19, and the concentrated liquid L4 is treated by an ozone ultraviolet ray promoted oxidation method. That is, by adding ozone as an oxidizing agent to the concentrated liquid L4 and irradiating ultraviolet rays, the concentrated liquid L4
Organic matter inside is decomposed. An aeration tube connected to the ozone generator 19 is provided in the tank 18 containing the concentrated liquid L4, and the organic matter in the concentrated liquid L4 is mixed with ozone in the tank 18, for example, at a wavelength of 254 nm or 365.
It is decomposed by being irradiated with ultraviolet rays mainly containing light of nm. In this case, it is preferable to provide an ultraviolet lamp in the concentrated liquid L4 to be treated and to irradiate ultraviolet rays from the inside of the concentrated liquid L4 from the viewpoint of the decomposition efficiency of organic substances. The concentrated liquid L4 may be sprayed or allowed to flow down the lamp wall, and the lamp wall may be covered with the concentrated liquid L4. Further, light irradiation may be performed while circulating the concentrated solution L4.

The concentrated solution L4 is subjected to a predetermined chemical oxidation treatment in the tank 18 to become a low-concentration chemically treated solution L6.
At this time, when the organic substance concentration of the chemical treatment liquid L6 is equal to or higher than a predetermined value, the chemical treatment liquid L6 is supplied to the pressure pump 16
To return to the concentration separation processing device 3. That is, the chemical treatment liquid L6 generated in the chemical oxidation treatment step is combined with the separation liquid L3. Chemical treatment liquid L merged with separation liquid L3
6 is subjected to a concentration separation treatment, and when it is processed to a predetermined concentration or lower, it is taken out as a processed liquid L5, and when it is higher than a predetermined concentration, it is sent again to the chemical oxidation treatment apparatus 4 as a concentrated liquid L4, It is subjected to a chemical oxidation treatment. Thus,
The concentrated liquid L4 (chemical treatment liquid L6) circulates through the concentration separation treatment step and the chemical oxidation treatment step until it is converted into a treated liquid L5 having an organic substance concentration equal to or lower than a predetermined value. Also,
Chemical treatment liquid L6 generated by chemical oxidation treatment device 4
When the concentration of the organic substance becomes equal to or less than the predetermined value, the chemical treatment liquid L6 can be taken out as the treated liquid L5. Further, when the intermediate product of the target organic substance in the chemical oxidation treatment step is biodegradable and does not become a precursor of a harmful substance, the intermediate product is combined with the water to be treated L1 as it is and returned to the biological treatment step. Can be.

In the present embodiment, the ozone ultraviolet ray promoted oxidation method is used as the chemical oxidation treatment step.
For example, photocatalysis, ozone aeration, hydrogen peroxide addition,
An ultraviolet ray method or an accelerated oxidation method using a combination of these methods can be used as appropriate. Further, in the photocatalytic method and the ultraviolet method, since the light irradiation efficiency increases as the amount of water decreases, the combination of the concentration method and the adsorption method is suitable or unsuitable. Also,
The oxidizing agent refers to a substance having an oxidizing effect, and has a function of giving oxygen, depriving hydrogen, depriving electrons, and the like, but is preferably one which does not easily remain in the treated liquid, such as an oxygen-based oxidizing agent and chlorine. It is preferable to use at least one of the oxidizing agents. Examples of the oxygen-based oxidizing agent include hydrogen peroxide, ozone, and air, and examples of the chlorine-based oxidizing agent include chlorine,
Hypochlorous acid and the like.

As described above, since the concentration separation treatment step is provided before the chemical oxidation treatment step, the separated liquid L3 is converted into a high-concentration concentrated liquid L4 in the concentration separation treatment step and then subjected to the chemical oxidation treatment treatment. Sent to the process. At this time, in the chemical oxidation treatment, the higher the concentration of the organic substance in the liquid to be treated, the higher the reactivity. Therefore, the concentrated solution L4 is efficiently treated with high reactivity. That is, since the concentration of the treated water L1 subjected to the biological treatment is low, it may not be possible to perform a highly reactive chemical oxidation treatment as it is, but the concentration is increased by performing the concentration separation treatment. Reactivity is maintained.
Therefore, the organic matter concentration is efficiently reduced.

The chemical treatment liquid L6 is returned to the concentration / separation treatment apparatus 3 by the pressure pump 16 to be combined with the separation liquid L3, and the treatment is efficiently performed by circulating the concentration / separation treatment step and the chemical oxidation treatment step. It can be carried out. That is, although the chemical oxidation treatment requires a large amount of energy, the time required for the chemical oxidation treatment can be minimized. In other words, the chemical treatment liquid L6 in which the concentration of the concentrated liquid L4 has been reduced to some extent by performing the chemical oxidation treatment for a predetermined time is returned to the concentration separation treatment step to be concentrated, the reactivity is increased, and then the chemical oxidation treatment is performed again. By repeating this operation, a highly reactive process can be performed while suppressing the chemical oxidation process time. As described above, by circulating the concentrated solution L4 (the chemical treatment solution L6) between the concentration separation treatment step and the chemical oxidation treatment step, a treatment that achieves both high reactivity and throughput is realized. On the other hand, by sufficiently treating the concentrated solution L4 in the chemical oxidation treatment step,
The load of the concentration separation process is reduced.

By performing the biological treatment step first, the concentrated liquid L4 in which the biodegradable organic matter is sufficiently reduced is supplied to the chemical oxidation treatment step, so that the possibility of generation of an inhibitory substance is reduced. Is done. Further, since a part of the organic matter to be decomposed in the chemical oxidation treatment step is decomposed in the biological treatment step, the load of the chemical oxidation treatment step is reduced.

Next, a water treatment method and a water treatment apparatus according to a second embodiment of the present invention will be described with reference to FIG. In FIG. 3, the water treatment device B includes a biological treatment device 1, a solid-liquid separation treatment device 2, a concentration separation treatment device 3, and a chemical oxidation treatment device 4, as in the first embodiment. In the present embodiment, it is assumed that the water L1 to be treated contains volatile harmful organic substances such as trichloroethylene. Further, the concentration and separation treatment device 3 and the chemical oxidation treatment device 4 have the same configuration as in the first embodiment, and a description thereof will be omitted below.

In the present embodiment, the immersion type membrane separation activated sludge method is used as the biological treatment step, and the membrane separation activated sludge method has a configuration which also has a solid-liquid separation treatment step. That is, the water to be treated L1 stored in the tank 31
Is subjected to a treatment by a membrane separation activated sludge method while being continuously ventilated by a blower 11, and is supplied to a concentration separation treatment device 3 as a separated liquid L3. At this time, volatile organic matter is generated as gas G from the water to be treated L1. The gas G discharged from the tank (volatilizer) 31 is collected by a duct 34 and sent to a chemical gas oxidation treatment device 33 that chemically oxidizes and decomposes organic substances in the gas G. The step of collecting gas G may be provided before or after activated sludge. That is, the volatilization step can be provided at least one of the former stage and the latter stage of the biological treatment step. The chemical gas oxidation treatment device 33 decomposes the gas G by bringing the supplied gas G into contact with a dry photocatalyst and irradiating the gas G with light such as ultraviolet rays.

As described above, the volatilization step is provided in at least one of the former stage and the latter stage of the biological treatment step, and the gas G discharged from the volatilization step is provided separately from the chemical oxidation treatment step. By treating in the process, for example, even when the organic matter contained in the water to be treated L1 has volatility, this organic matter is surely treated. At this time, the gas G can also be treated by making the microorganisms in the biological treatment process aerobic.

When the volatilization step is provided before the biological treatment step, the load on the biological treatment step is reduced. On the other hand, when the volatilization step is provided after the biological treatment step, the volatility generated in the biological treatment step is reduced. Organics can also be removed in the volatilization step.

[0025]

The water treatment method and the water treatment apparatus of the present invention have the following effects. (1) The biological treatment liquid obtained by biodegrading the water to be treated is converted into a high-concentration liquid mainly containing a biodegradable organic substance in the concentration separation treatment step. Therefore, the chemical oxidation treatment performed in the subsequent stage is efficiently performed while maintaining high reactivity. In addition, by performing the biological treatment first, the biodegradable organic substance is not supplied to the chemical oxidation treatment step, so that the possibility of generating an inhibitory substance is reduced, and the treatment can be performed efficiently. (2) The chemical treatment liquid generated in the chemical oxidation treatment step is
By combining with any of the water to be treated, the separated liquid, and the treated liquid, the treatment is efficiently performed. That is, the chemical oxidation treatment consumes a large amount of energy. For example, a chemical treatment liquid having a predetermined concentration is generated by performing the chemical oxidation treatment for a predetermined time, and the chemical treatment liquid is returned to the concentration / separation treatment step to be concentrated. By sending to the chemical oxidation treatment step again with the enhanced reactivity, a highly reactive treatment can be performed while suppressing the chemical oxidation treatment time. (3) A volatilization step is provided in at least one of the former stage and the latter stage of the biological treatment step, and the gas discharged from the volatilization step is treated in a chemical gas oxidation treatment step provided separately from the chemical oxidation treatment step. Thereby, for example, even when the organic matter contained in the water to be treated has volatility, the organic matter is surely treated. At this time, the microorganism can also be treated in the biological treatment step by making the microorganism aerobic.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a water treatment apparatus of the present invention.

FIG. 2 is a configuration diagram for explaining a concentration separation processing apparatus.

FIG. 3 is a configuration diagram showing a second embodiment of the water treatment apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Biological processing apparatus 2 Solid-liquid separation processing apparatus 3 Concentration separation processing apparatus 4 Chemical oxidation processing apparatus 11 Blower 13 Sludge return pump 16 Pressure pump 17 Reverse osmosis filtration part 19 Ozone generator 33 Chemical gas oxidation processing apparatus L1 Water L2 Biological treatment liquid L3 Separation liquid L4 Concentrate L5 Treated liquid L6 Chemical treatment liquid S1 Solid content G Gas

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Claims (6)

[Claims] 1. A biological treatment step of treating a water to be treated containing an organic substance using a microorganism to produce a biological treatment liquid; and a solid-liquid separation treatment step of separating the biological treatment liquid into a solid content and a separated liquid. A concentration separation treatment step of concentrating the separated liquid to separate a concentrated liquid having a concentration of an organic substance equal to or more than a predetermined value and a treated liquid having a concentration equal to or less than a predetermined value, and chemically separating the organic substance contained in the concentrated liquid. And a chemical oxidation treatment step of performing an oxidation treatment. 2. The water treatment method according to claim 1, wherein the chemical treatment liquid generated in the chemical oxidation treatment step is combined with any of the water to be treated, the separation liquid, and the treated liquid. A water treatment method characterized by the above-mentioned. 3. The water treatment method according to claim 1, wherein a volatilization step is provided in at least one of a former stage and a latter stage of the biological treatment step, and a gas discharged from the volatilization step is subjected to the chemical treatment. A water treatment method, wherein the treatment is performed in a chemical gas oxidation treatment step provided separately from the oxidation treatment step. 4. The water treatment method according to claim 1, wherein the microorganisms in the biological treatment step are made aerobic. 5. A biological treatment device that treats water to be treated containing an organic substance using a microorganism to produce a biological treatment liquid, and a solid-liquid separation treatment device that separates the biological treatment liquid into a solid content and a separated liquid. A concentration separation treatment apparatus for concentrating the separated liquid to separate a concentrated liquid having a concentration of an organic substance equal to or higher than a predetermined value and a treated liquid having a concentration equal to or lower than a predetermined value, and chemically separating the organic substance contained in the concentrated liquid A water treatment apparatus, comprising: a chemical oxidation treatment apparatus for performing an oxidation treatment. 6. The water treatment apparatus according to claim 5, wherein the volatilization apparatus is provided in at least one of a stage before and after the biological treatment device and volatilizes the water to be treated or the biological treatment liquid. A water treatment apparatus comprising: a chemical gas oxidation treatment apparatus for chemically oxidizing organic substances in gas discharged from the apparatus.