JPH1043792A - Sewage treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to maintain the absolute anaerobic state in a first anaerobic treating stage and a second anaerobic treating stage where aerobic treated water does not circulate and to stably and efficiently execute a decomposition removal treatment of org. matter included in sewage while maintaining the characteristic that the amt. of the sludge to be formed is little when particularly solid biological membranes are used. SOLUTION: This device is provided with respectively >=2 units of the first anaerobic treating stage 1A to 1D, second anaerobic treating stage 2A to 2D and aerobic treating stages 3A to 3D which treat sewage stepwise in juxtaposition. Part of the treated water of the aerobic treating stages 3A to 3D is circulated to at least >=1 of the second anaerobic treating stage 2A to 2D and the injection of chemicals to the second anaerobic treating stage 2A to 2D where the circulation of the aerobic treated water exists is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewage treatment apparatus for anaerobic and aerobic treatment of sewage containing organic substances and the like.

[0002]

2. Description of the Related Art As a conventional sewage treatment method, there is, for example, an organic wastewater treatment method disclosed in Japanese Patent Publication No. 3-76999, and FIG. 4 is a flow sheet diagram thereof. In this method for treating organic wastewater, organic wastewater is sequentially flown into first and second anaerobic filter tanks to perform anaerobic treatment stepwise, and the treated water from the second anaerobic filter tank is preferably used. The anaerobic filter tank is introduced into the aerobic filter tank to oxidize and decompose organic substances contained in the treated water and nitrify the nitrogen component, and a part of the treated water in the aerobic filter tank is circulated to the second anaerobic filter tank. At the same time, the washing and drainage of the aerobic filter tank and the excess sludge are intermittently returned to the first anaerobic filter tank.

According to such a conventional method for treating organic wastewater, the solubilization of organic substances and the promotion of an acid generation reaction in the first anaerobic filter bed tank can be promoted, and accordingly, the second anaerobic filter can be promoted. In the bed tank, effects such as efficient denitrification reaction being promoted and the load on the aerobic filter bed tank being reduced can be obtained.

[0004] Here, the sewage treatment method combining the anaerobic treatment step and the aerobic treatment step can be expected to remove organic substances stably, and the sewage treatment by the anaerobic / aerobic filter method using a fixed biofilm. The method can save energy,
It has characteristics such as extremely low sludge generation and easy maintenance.

[0005]

The method for treating organic wastewater disclosed in the prior art comprises the above-described process, and circulates a part of the treated water from the aerobic filter tank to the second anaerobic filter tank. Therefore, the anaerobic state in the second anaerobic filter tank is impaired. Therefore, there is a problem that the characteristic of the anaerobic treatment, that is, the characteristic that the sludge generation amount is extremely small by sufficient digestion treatment is canceled. In particular, in the sewage treatment method by the anaerobic and aerobic bed method using a fixed biofilm,
There is a problem that the nitrogen removal rate is low and the phosphorus removal rate is also low, and this has been a problem in that it is a major weak point in the current trend of sewage treatment toward advanced treatment.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises the steps of separating organic wastewater in a first anaerobic treatment step and a second anaerobic treatment step in which treated water in the aerobic treatment step is not circulated. By performing anaerobic treatment, organic matter contained in sewage can be decomposed and removed stably and efficiently, and in this stepwise anaerobic treatment process, the characteristic of anaerobic treatment that sludge generation is extremely small In the aerobic treatment step, the treated water of the aerobic treatment step is included in the treated water from the second anaerobic treatment step in which the treated water of the aerobic treatment step is circulated and the treated water of the aerobic treatment step is not circulated. Performs oxidative decomposition of organic matter and nitrification of nitrogen components, and a part of the treatment water of the aerobic treatment step containing oxidized nitrogen is circulated to at least one or more second anaerobic treatment steps and denitrified. Like And to obtain a sewage treatment apparatus.

[0007]

According to a first aspect of the present invention, there is provided a sewage treatment method according to the present invention, wherein each of the first anaerobic treatment step, the second anaerobic treatment step, and the aerobic treatment step for treating sewage stepwise is performed. A sewage treatment apparatus provided in parallel with at least two or more sewage treatment apparatuses, a flow path for circulating a part of the treatment water of the aerobic treatment step for at least one or more second anaerobic treatment steps, A facility for injecting a chemical into the second anaerobic treatment step in which the treated water of the step is circulated.

According to a second aspect of the present invention, there is provided the sewage treatment method, wherein each of the first anaerobic filter tank, the second anaerobic filter tank, and the aerobic filter tank for treating sewage stepwise has at least two filters.
In a sewage treatment apparatus provided in parallel with two or more, a flow path for circulating a part of the treatment water of the aerobic filter tank to at least one or more second anaerobic filter tanks, And a facility for injecting a chemical into a second anaerobic filter bed tank through which treated water in the bed tank circulates.

According to a third aspect of the present invention, there is provided a sewage treatment apparatus wherein the treated water of the second anaerobic filter tank and the treated water of the aerobic filter tank in which the treated water of the aerobic filter tank circulates are not circulated. It is provided with a merging flow path for once merging the treated water of the bi-anaerobic filter bed tank and a distribution flow path for distributing the merged treated water to each aerobic filter bed tank.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a flow sheet diagram showing a sewage treatment apparatus according to Embodiment 1 corresponding to the first aspect of the present invention. In FIG. 1, 1A, 1B, 1C, 1D (hereinafter, referred to as 1A, 1B, 1C, 1D)
1A to 1D) are respectively installed in parallel, are anaerobic treatment steps for anaerobic treatment of inflowing wastewater, after these first anaerobic treatment steps 1A to 1D,
The same number of second anaerobic treatment steps 2A, 2
B, 2C, and 2D (hereinafter, referred to as 2A to 2D) are provided in parallel. These second anaerobic treatment steps 2A-2
D has flow paths P1, P2, P3, P4 (hereinafter, referred to as flow paths P1, P2, P3, P4, respectively).
P1 to P4) through the first anaerobic treatment step 1A to
The treatment water from 1D is introduced.

3A, 3B, 3C, 3D (hereinafter, 3A to 3
D) are the same number of aerobic treatment steps installed in parallel after the second anaerobic treatment steps 2A to 2D, and these aerobic treatment steps 3A to 3D include flow paths P5 and P, respectively.
6, P7, P8 (hereinafter, referred to as P5 to P8), the treated water of the second anaerobic treatment step 2A to 2D is introduced.

Reference numeral 4 denotes a treatment water tank for introducing treated water from the aerobic treatment steps 3A to 3D via a merging flow path P9, and P10 designates a part of the treated water from the treatment water tank 4 in the second anaerobic treatment steps 2A to 2A.
A circulation channel for circulating between 2A and 2B in 2D,
Reference numeral 5 denotes a chemical injecting facility for injecting chemicals into the second anaerobic treatment steps 2A and 2B in which the treated water circulates from the treated water tank 4. P11 is the second anaerobic treatment step 2A to 2 from the treatment water tank 4.
A backwash channel for sending backwash water to each of the 2D and each of the aerobic treatment steps 3A to 3D, and P12 is used for each of the second anaerobic treatment steps 2A to 2D and the aerobic treatment steps 3A to 3D. First anaerobic treatment step 1A from each
This is a washing channel for returning washing water and sludge to 1D.

Here, the sewage treatment by the above process will be described. After the sewage flows into each of the first anaerobic treatment steps 1A to 1D and is subjected to the anaerobic treatment, the treated water is passed through the flow paths P1 to P4 and the second anaerobic treatment step 2
Aerobic treatment is further performed by advancing to each of A to 2D. Next, the treated water of the second anaerobic treatment steps 2A to 2D is supplied to the next aerobic treatment step 3A to 3A through channels P5 to P8.
Sent to each of the 3D anaerobic treatment steps 2A-2
Oxidative decomposition of organic substances contained in the treated water of D and nitrification of nitrogen components are performed.

Further, the treated water in the aerobic treatment steps 3A to 3D is sent to the treated water tank 4 through the flow path P9, and from the treated water tank 4 through the circulation flow path P10.
Part of the treated water of D is circulated to 2A and 2B among the second anaerobic treatment steps 2A to 2D, and denitrification of oxidized nitrogen contained in the circulated treated water is performed.

In such a process, in 2C and 2D of the first anaerobic treatment steps 1A to 1D and the second anaerobic treatment steps 2A to 2D having no circulation from the treatment water tank 4,
The anaerobic treatment is maintained in an absolutely anaerobic state, and the anaerobic treatment is performed stably and efficiently. Especially in the case of treatment using a fixed biofilm,
While maintaining the original characteristics of low sludge generation,
The organic matter contained in the sewage is decomposed and removed.

Further, the aerobic treatment step 3A
~ 2D anaerobic treatment step 2A with circulation of treated water
In 2A and 2B of 2D, since oxygen supply such as aeration is not particularly performed, the state is maintained in an anoxic state of a facultatively anaerobic state, and is included in the circulating aerobic treatment process 3A to 3D treated water. Denitrification of the oxidized nitrogen is performed.

Further, an aerobic treatment step 3A is performed from the treatment water tank 4.
To the second anaerobic treatment steps 2A and 2B, which have circulation of the treated water of ~ 3D, the treated water of the first anaerobic treatment steps 1A and 1B containing an organic substance which can be an effective organic carbon source for the denitrification reaction, respectively. Come in. Thereby, the second anaerobic treatment step 2
In A and 2B, the denitrification reaction is smoothly promoted.

As described above, the first anaerobic treatment steps 1A to 1
The processing step composed of 1A and 1B of D and the second anaerobic processing steps 2A and 2B that are the next step,
This is an anaerobic treatment step of performing a denitrification treatment of circulating treated water, and 1C, 1 of the first anaerobic treatment steps 1A to 1D.
D, and a second anaerobic treatment step 2C that is the next step,
The processing step composed of each of 2D is an anaerobic processing step in which only the anaerobic processing is performed and the original characteristic that the sludge generation amount is small is maintained.

Next, the denitrification treatment in the second anaerobic treatment steps 2A and 2B and the stable anaerobic treatment in the other second anaerobic treatment steps 2C and 2D are performed in parallel and in multiple stages. After the treatment, the treated water flows into the aerobic treatment steps 3A to 3D via the flow paths P5 to P8, respectively, where the oxidative decomposition treatment of the remaining organic substances and the nitrification treatment of the nitrogen component are performed.

In the second anaerobic treatment steps 2A and 2B, a denitrification treatment of oxidized nitrogen contained in the circulating treated water is performed, but an organic substance which can be an effective organic carbon source for the denitrification reaction is provided. Since the treated waters of the first anaerobic treatment steps 1A and 1B containing water respectively flow in, the denitrification reaction is smoothly promoted. Therefore, the amount of chemicals that can be an organic carbon source can be significantly reduced in the second anaerobic treatment steps 2A and 2B, which is economical. And in the 2nd anaerobic treatment process 2A and 2B, since a denitrification process is mainly performed, a denitrification rate can be calculated theoretically and operation management is easy.

Note that, depending on the amount and water quality of the inflowing sewage, the treated water in the first anaerobic treatment steps 1A and 1B lacks an organic substance that can be an effective organic carbon source for the denitrification reaction, and the second anaerobic treatment step 2A It is also conceivable that the denitrification reaction in 2B and 2B is not smoothly promoted. When the amount of the organic matter that can be an organic carbon source becomes extremely small, the circulation of the treated water from the treated water tank 4 to the second anaerobic treatment steps 2A and 2B is stopped. A chemical injection facility 5 is provided so that a chemical that can be an organic carbon source can be injected into the second anaerobic treatment steps 2A and 2B.

In FIG. 1, each of the first anaerobic treatment step, the second anaerobic treatment step, and the aerobic treatment step is provided in parallel with four each. However, this is not limited to providing four at a time, and should be increased or decreased according to the amount and quality of incoming sewage. Similarly, the circulation of the aerobic treated water and the injection of the chemicals are performed for two of the second anaerobic treatment steps 2A to 2D, 2A and 2B. Corresponding to
It is appropriately increased or decreased.

Further, the treated water in the aerobic treatment steps 3A to 3D is introduced into the treated water tank 4 through the flow path P9, but the treated water in the aerobic treatment steps 3A to 3D is treated in individual flow paths. It may be introduced into the water tank 4.

As described above, in the first embodiment, when the total amount of inflow sewage per day for the first anaerobic treatment steps 1A to 1D = Q, the amount of circulating water from the treatment water tank 4 to the second anaerobic treatment steps 2A and 2B Is set to 0.5Q to 3.0Q in total. In each of the second anaerobic treatment steps 2A to 2D and each of the aerobic treatment steps 3A to 3D, backwashing is performed about 0 to 3 times a day with backwash water from the treatment water tank 4, and the backwash is performed. Wash water and sludge generated by the first anaerobic treatment process 1A ~
Returned to 1D.

Embodiment 2 FIG. 2 is a flow sheet diagram showing a sewage treatment apparatus according to a second embodiment corresponding to the second aspect of the present invention. In FIG. 2, 11A, 11B, 1
1C and 11D (hereinafter referred to as 11A to 11D) are first anaerobic filter tanks which are installed in parallel and anaerobically treat inflowing wastewater.
After A to 11D, the same number of independent second anaerobic filter tanks 12A, 12B, 12C, 12D (hereinafter, 1) are respectively provided.
2A to 12D) are provided in parallel. In these second anaerobic filter tanks 12A to 12D, flow paths P1, P2, P3 and P4 (hereinafter referred to as P1 to P4), respectively.
Through which the treated water from the first anaerobic filter tanks 11A to 11D is introduced.

13A, 13B, 13C, 13D (hereinafter referred to as 13A, 13B, 13C, 13D)
13A-13D) are the second anaerobic filter tanks 12A-1.
The same number of aerobic filter tanks are installed in parallel after 2D, and these aerobic filter tanks 13A to 13D have channels P5, P6, P7, and P8, respectively (hereinafter, referred to as P5 to P8). Through which the treated water in the second anaerobic filter tanks 12A to 12D is introduced.

Reference numeral 14 denotes a treated water tank for introducing treated water from the aerobic filter tanks 13A to 13D through the flow path P9, and P10 transfers a part of the treated water from the treated water tank 4 to the second anaerobic filter tanks 12A to 12A.
Circulation flow path for circulating 12D and 12B out of 12D, 15 is a chemical (eg, lower alcohol or lower alcohol) that can be an organic carbon source to second anaerobic filter tanks 12A and 12B in which treated water circulates from treated water tank 4. Acetic acid etc.).

P11 is a backwash channel for feeding backwash water from the treatment water tank 4 to each of the second anaerobic filter tanks 12A to 12D and each of the aerobic filter tanks, and P12 is a second anaerobic filter tank. Each of the filter bed tanks 12A to 12D and the aerobic filter bed tank 1
The first anaerobic filter tank 11A from each of 3A to 13D
This is a washing channel for returning washing water and sludge generated by back washing to 11D.

In the sewage treatment apparatus configured as described above, sewage treatment can be performed by the same process as that of the sewage treatment apparatus described in the first embodiment. The same operation and effect as described above can be obtained.

Incidentally, the first anaerobic filter tank 1 in the present invention.
1A to 11D and the second anaerobic filter tanks 12A to 12D are filled with a filter medium for attaching a biofilm. If turbulence occurs, the biofilm will peel off and the treatment efficiency will decrease. Therefore, filter media include dish, cylinder,
It is necessary to use a reticulated body, a string-shaped body, or the like having particularly excellent adhesion of a biofilm. Similarly, aerobic filter tanks 13A-1
Also in 3D, it is necessary to use a filter medium as described above, which has good adhesion to a biofilm even under flow due to aeration or the like and has excellent trapping properties for suspended substances.

Embodiment 3 FIG. 3 is a flow sheet diagram showing a sewage treatment apparatus according to Embodiment 3 corresponding to the third aspect of the present invention. In FIG. 3, P13 is connected to each of the second anaerobic filter tanks 12A to 12D, and serves as a merging flow path for once joining the treated water from the second anaerobic filter tanks 12A to 12D, Further, P14 connects the merging flow path P13 and each of the aerobic filter tanks 13A to 13D, and combines the treated water from the second anaerobic filter tanks 12A to 12D into each of the aerobic filter tanks 13A to 13D. This is a distribution flow path for distributing and inflowing the fluid into the flow path.

That is, the second anaerobic filter tanks 12A to 12D
Among the treated water from 12A and 12B, the denitrification treatment was performed in a facultatively anaerobic state.
Since the treated water from 2D has been subjected to anaerobic treatment in an absolutely anaerobic state, each treated water has a different water quality.
For this reason, after the respective treated waters are merged in the merged flow path P13 and the water quality is homogenized, the merged treated water is distributed and flows into the aerobic filter tanks 13A to 13D in the distribution flow path P14.

In the aerobic filter bed tanks 13A to 13D into which the combined treatment water homogenized as described above flows, the treatment can be performed under the same operating conditions. It is also effective in terms of.

In the sewage treatment apparatus configured as described above, except for the merging flow path P13 and the distribution flow path P14, sewage treatment is performed in the same process as the sewage treatment apparatus described in the second embodiment. Therefore, the same operation and effect as those of the second embodiment can be obtained.

[0035]

As described above, according to the first aspect of the present invention, each of the first anaerobic treatment step, the second anaerobic treatment step, and the aerobic treatment step for treating sewage stepwise is at least two. A second anaerobic treatment in which at least one or more second anaerobic treatment steps are provided in parallel, and at least one or more second anaerobic treatment steps circulate a part of the treatment water of the aerobic treatment step, and the circulation of aerobic treatment water Since the process is capable of injecting chemicals into the process, in this process the absolute anaerobic state can be maintained in the first anaerobic treatment step and the second anaerobic treatment step where aerobic treated water does not circulate, When the membrane is used, there is an effect that the treatment for decomposing and removing the organic substances contained in the sewage can be stably and efficiently performed while maintaining the characteristic that the sludge generation amount is small. In the second anaerobic treatment step in which aerobic treated water containing oxidized nitrogen is circulated, the treated water of the first anaerobic treatment step containing an organic substance that can be an effective organic carbon source for the denitrification reaction flows in. The denitrification reaction is smoothly promoted, and the amount of chemicals that can be an organic carbon source to the second anaerobic treatment step in which aerobic treated water circulates can be significantly reduced, which is economical. effective. In the second anaerobic treatment step in which the aerobic treated water circulates, the denitrification treatment is mainly performed, so that the denitrification rate can be theoretically calculated and the operation can be easily managed. Furthermore, the number of treatment systems to be operated and operated and the number of second anaerobic treatment steps for circulating aerobic treated water can be appropriately changed in accordance with the amount and quality of the inflowing wastewater. There is also an effect that it can respond to.

According to the second aspect of the present invention, each of the first anaerobic filter tank, the second anaerobic filter tank and the aerobic filter tank for treating sewage stepwise is arranged in parallel with at least two or more. And a second anaerobic filter tank having a circulation of aerobic treated water while circulating a part of the treatment water of the aerobic filter tank in at least one or more second anaerobic filter tanks In this process, the process can be used to inject chemicals into
The first anaerobic filter tank and the second anaerobic filter tank in which aerobic treated water does not circulate can maintain an absolute anaerobic state,
In particular, since the process uses a fixed biofilm, there is an effect that a process of decomposing and removing organic substances contained in sewage can be stably and efficiently performed while maintaining the characteristic that the amount of generated sludge is small. In the second anaerobic filter tank in which aerobic treated water containing oxidized nitrogen is circulated, the treated water in the first anaerobic filter tank containing organic substances that can be an effective organic carbon source for the denitrification reaction is used. The denitrification reaction is smoothly promoted due to the inflow, and the amount of chemicals that can be a source of organic carbon into the second anaerobic filter tank in which aerobic treated water circulates can be significantly reduced. There is an effect that is. Also,
In the second anaerobic filter tank in which the aerobic treated water circulates, the denitrification treatment is mainly performed, so that the denitrification rate can be theoretically calculated and the operation can be easily managed. Furthermore, the number of treatment systems to be operated and the number of second anaerobic filter tanks for circulating aerobic treated water can be appropriately changed according to the amount and quality of the inflowing sewage. There is also an effect that it can be easily handled. Furthermore, since each filter bed tank uses a filter medium in which a biofilm is stably held, there is an effect that the treatment can be performed stably and efficiently.

According to the third aspect of the present invention, after the treated water from the plurality of second anaerobic filter tanks is once merged, the combined treated water is distributed and flowed into the plurality of aerobic filter tanks. Since the process is the same as that of the invention described in claim 2,
Thereby, since the homogenized combined treatment water flows into each aerobic filter bed tank, the treatment can be performed under the same operating conditions, and at the same time, it is effective in terms of maintenance.

[Brief description of the drawings]

FIG. 1 is a flow sheet diagram showing a sewage treatment apparatus according to a first embodiment corresponding to the first aspect of the present invention.

FIG. 2 is a flow sheet diagram showing a sewage treatment apparatus according to a second embodiment corresponding to the invention described in claim 2;

FIG. 3 is a flow sheet diagram showing a sewage treatment apparatus according to a third embodiment corresponding to the invention described in claim 3;

FIG. 4 is a flow sheet diagram showing a conventional sewage treatment apparatus.

[Explanation of symbols]

 1A to 1D First anaerobic treatment step 2A to 2D Second anaerobic treatment step 3A to 3D Aerobic treatment step 11A to 11D First anaerobic filter tank 12A to 12D Second anaerobic filter tank 13A to 13D Aerobic Filter bed tank 4 Treatment water tank 5 Chemical injection equipment P10 Circulation channel P13 Merging channel P14 Distribution channel

Claims (3)

[Claims] 1. A sewage treatment apparatus in which at least two of a first anaerobic treatment step, a second anaerobic treatment step, and an aerobic treatment step for treating sewage stepwise are provided in parallel. Chemicals are injected into a channel for circulating a part of the treatment water of the aerobic treatment step to one or more second anaerobic treatment steps and a second anaerobic treatment step where the treatment water of the aerobic treatment step circulates A sewage treatment apparatus comprising: 2. A sewage treatment apparatus in which at least two of a first anaerobic filter tank, a second anaerobic filter tank and an aerobic filter tank for treating sewage stepwise are provided in parallel. A flow path for circulating a part of the treated water of the aerobic filter tank with respect to at least one or more second anaerobic filter tanks, and a second anaerobic where the treated water of the aerobic filter tank circulates A sewage treatment apparatus, comprising: a facility for injecting a chemical into a filter bed tank. 3. The treated water of the second anaerobic filter tank in which the treated water of the aerobic filter tank circulates and the treated water of the second anaerobic filter tank in which the treated water of the aerobic filter tank does not circulate. 3. The sewage treatment apparatus according to claim 2, further comprising a merging flow path for once merging and a distribution flow path for distributing and supplying the merged treated water to each aerobic filter bed tank.