JPH10109004A - Waste water treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To introduce an advanced treating system to an existing sewage treatment works. SOLUTION: The inside of an upward stream passage 6 is used as a solid-liq. separating part A by providing an upward stream passage 6 in which the primary treated water 3 flowing from a settling tank 2 flows upward by dividing a part of an inlet part in a biological treating tank 4 with a partition 4a and forming a filter medium layer 8 with the filter medium lower in specific gravity than the primary treated water 3 in the upward stream passage 6, and the inside of the tank at a downstream side than the upward stream passage 6 is used as a biological treating part B. In this way, the advanced treating system is introduced only by renovating a part of the existing biological treating tank 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment apparatus provided with a sedimentation pond and a biological treatment tank.

[0002]

2. Description of the Related Art Generally, when treating wastewater such as sewage,
Wastewater is led to the first settling basin, the biological treatment tank and the final settling basin.

For example, in a sewage treatment using a standard activated sludge method as shown in FIG. 4, sewage 1 is first introduced into a sedimentation basin 2, and solids contained in the sewage 1 are separated by gravity sedimentation.
The primary treated water 3 flowing out of the first sedimentation basin 2 is transferred to the biological treatment tank 4
Leading to.

[0004] In the biological treatment tank 4, the partition wall 4 a
The primary treatment water 3 is sequentially flown into each treatment section 4b separated in the above, so that the organic matter and nitrogen in the primary treatment water 3 can be removed from the tank under various conditions in each treatment section 4b, for example, under different oxygen supply conditions. Decomposed and removed by floating activated sludge. Then, the secondary treatment water 5 flowing out of the biological treatment tank 4 is guided to a final sedimentation basin (not shown).

[0005] The sewage residence time in the biological treatment tank 4 in such a treatment is 6 times when only organic matter is removed.
8 hours, and 16 when nitrogen is to be removed.
~ 24 hours.

For this reason, a high-efficiency solid-liquid separation means is disposed in front of the biological treatment tank 4 to reduce the load of solids and organic substances.
An advanced treatment system for removing nitrogen in the biological treatment tank 4 has been proposed.

As one of the high-efficiency solid-liquid separation means, there is a solid-liquid separation device filled with a filter medium. For example, this apparatus fills a tank with a filter medium having an appropriate specific gravity which can be suspended in the water to be treated, and allows sewage to flow therethrough as an upward flow. Are captured and removed. For example, a cylindrical hollow filter medium made of plastic (15 mmφ
× 15 mmL) at a layer height of 0.5 m,
When raw sewage is passed at a water area load of 200 m ³ / m ² · day, the raw water SS concentration is 41 to 206 as shown in FIG.
mg / L, the SS concentration of the treated water is 22 to 3
It was 8 mg / L, and good treated water was stably obtained.

[0008] Therefore, if the filtered water from which solids and organic substances are removed is biologically treated by such a filter material-filled solid-liquid separator, water quality equivalent to or better than the conventional one can be obtained in a processing time shorter than the conventional one. It is thought that it is possible.

[0009]

However, when this system is introduced into a large- to medium-sized existing sewage treatment plant in which the first sedimentation basin and the biological treatment tank exist as existing facilities, the sewage in the first sedimentation basin is horizontal. Since the water flows and the solid-liquid separation device filled with the filter medium as described above is usually passed as an upward flow, it is difficult to directly introduce the configuration of the solid-liquid separation device filled with the filter medium into the first settling tank.

An object of the present invention is to solve the above-mentioned problem, and an object of the present invention is to make it possible to easily introduce an advanced treatment system into an existing sewage treatment plant.

[0011]

According to a first aspect of the present invention, there is provided a wastewater treatment apparatus for introducing wastewater such as sewage and separating solids contained in the wastewater by gravity sedimentation. A sedimentation basin, and a wastewater treatment apparatus provided with a biological treatment tank for introducing and treating the primary treated water flowing out of the sedimentation basin, wherein a part of the inflow portion in the biological treatment tank is separated by a partition wall. , A filter material-filled layer is provided inside, and the inside of the partition wall is formed as a solid-liquid separation section, and the inside of the tank downstream of the solid-liquid separation section is formed as a biological treatment section.

According to a second aspect of the present invention, in the wastewater treatment apparatus, a part of the inflow portion in the biological treatment tank is divided by a partition, and a supply means for supplying primary treated water inside and below the partition is provided. An upward flow path through which the primary treated water flows upward is formed, and a filter medium-filled layer is formed in the upward flow path by a filter medium having a specific gravity smaller than that of the primary treated water. It is a thing.

[0013] In the wastewater treatment apparatus according to the third aspect, a coagulant injecting an inorganic coagulant or a polymer coagulant into the middle of the flow path of the primary treatment water from the solid-liquid separation unit or the sedimentation tank to the solid-liquid separation unit. Means are provided.

According to a fourth aspect of the present invention, there is provided a wastewater treatment apparatus provided with a cleaning means for cleaning a filter medium by stirring and flowing the filter medium inside the partition wall. According to a fifth aspect of the present invention, in the wastewater treatment apparatus, the biological treatment section is provided with a carrier that carries a biofilm.

According to a sixth aspect of the present invention, in the wastewater treatment apparatus, the biological treatment section is provided with a denitrification section and a nitrification section, and the nitrification section is supplied with a floating carrier for carrying nitrifying bacteria. According to the configuration of the first aspect, the primary treated water introduced into the biological treatment tank from the sedimentation basin flows into the solid-liquid separation section formed inside the partition wall, and the solid-liquid separation is performed in the filter medium packed bed. As a result, the filtered water having a reduced solid matter load and organic matter load flows into the biological treatment section and is subjected to biological treatment, thereby increasing the treatment efficiency.

According to the second aspect of the present invention, the filter medium is in a floating state, and is gathered by the flow of the primary treatment water to form a packed bed. The solid matter trapped between the filter media can be released, and the clogging of the filter media packed layer can be prevented.

According to the third aspect of the present invention, the inorganic coagulant or the polymer coagulant is injected by the coagulant injection means in the middle of the flow of the primary treatment water from the solid-liquid separation unit or the sedimentation tank to the solid-liquid separation unit. By injecting, phosphorus and the like contained in the primary treatment water can be aggregated to form flocs, and can be removed in the solid-liquid separation section.

According to the fourth aspect of the present invention, the filter medium is agitated and flown by the washing means as described above, and the filter medium,
Alternatively, the solid matter trapped between the filter media can be released, and the clogging of the filter media packed layer can be prevented.

According to the structure of the fifth aspect, the microorganisms carried on the carrier as a biofilm do not flow out of the tank.
A high concentration of microorganisms can be held in the tank, and organic matter and nitrogen can be efficiently biodegraded. Therefore, it is possible to obtain a water quality equal to or higher than that of the treatment using the floating activated sludge even with a smaller tank volume when using the floating activated sludge.

According to the sixth aspect of the present invention, since the denitrification section and the nitrification section are provided, nitrogen can be efficiently removed.
Since the floating carrier supporting nitrifying bacteria flows by aeration performed in the nitrification section, the chance of contact between the nitrifying bacteria and the object to be treated is increased, and nitrification can be performed efficiently.

[0021]

An embodiment of the present invention will be described below with reference to the drawings. The wastewater treatment device shown in FIG. 1 is a modification of the conventional wastewater treatment device shown in FIG. 4, in which wastewater such as sewage 1 is introduced and solid matter contained in the wastewater is separated by gravity sedimentation. There is provided a sedimentation basin 2 and a biological treatment tank 4 for introducing the primary treated water 3 flowing out of the sedimentation basin 2 for biological treatment.

A coagulant injection pipe 3a for injecting a coagulant such as an inorganic coagulant or a polymer coagulant into the primary treatment water 3 is opened in the middle of the flow path from the first sedimentation tank 2 to the biological treatment tank 4. .
The biological treatment tank 4 is divided into a plurality of treatment sections 4b by a partition wall 4a. An inlet 4c is formed on one side of the sedimentation basin 2 first, and an outlet 4d is formed on the other opposite side. . However, the inflow port 4c is formed in the lower part of the tank, and the processing section 4b including the inflow port 4c forms the upward flow path 6.

The upward flow path 6 has a perforated plate 7 provided in a horizontal direction at a position near the inner water surface, and a filter medium layer 8 made of a filter medium having a specific gravity smaller than the average specific gravity of the primary treated water 3 below the perforated plate 7. Are formed, and constitute the solid-liquid separation part A. An air pipe 9 having a plurality of air ejection holes is provided below the filter medium layer 8.

Each processing section 4b downstream of the upward flow path 6
A first denitrification unit 10, a nitrification unit 11, a second denitrification unit 12, and a re-aeration unit 13 constitute a biological treatment unit B. Inside the first denitrification unit 10 and the second denitrification unit 12, plastic fixed-bed carriers 10a and 12a are provided.
Inside the nitrification section 11, a floating carrier 1 for supporting nitrifying bacteria is provided.
1a is turned on. Further, a circulation flow path 11 a for circulating and returning the nitrification liquid in the nitrification unit 11 is provided from the nitrification unit 11 to the upper part of the first denitrification unit 10.

The operation of the above configuration will be described below.
The sewage 1 first flows into a sedimentation basin 2 where solids which can settle out by gravity settling are removed.

Primary treated water 3 flowing out of first settling basin 2
After the coagulant is added from the coagulant injection pipe 3a, the coagulant flows into the upward flow path 6 of the treatment tank 4 from the inflow port 4c, flows upward through the inside thereof, and remains in the primary treatment water 3. Fine solids and phosphorus and the like flocculated by the flocculant are captured in the filter medium layer 8.

The filtered water 14 whose solid matter load and organic matter load are reduced by the filter medium layer 8 sequentially flows into the first denitrification unit 10, the nitrification unit 11, the second denitrification unit 12, and the re-aeration unit 13. And subject to treatment with an emphasis on nitrogen removal.
Flows out from the outlet 4d at the end as
It is sent to the final sedimentation basin (not shown).

At this time, in the first denitrification section 10, the filtered water 1
4 and the nitrification liquid 11a flow into the nitrification liquid 11a under anaerobic conditions while the organic matter in the filtered water 14 is used as a hydrogen source and a carbon source by the denitrifying bacteria attached to the fixed bed type carrier 10a. The returned nitrate nitrogen or nitrite nitrogen is reduced to nitrogen gas (partially nitrogen oxide gas) and removed. In the nitrification section 11, the floating carrier 1
Ammonia nitrogen in the filtered water 14 is oxidized to nitrate nitrogen or nitrite nitrogen by nitrifying bacteria or the like attached to 1a. In the second denitrification unit 12 and the re-aeration unit 13,
A biological reaction similar to that of the denitrification unit 10 and nitrification unit 11 occurs.

At this time, the denitrifying bacteria are fixed on the fixed bed type carrier 10.
Since the nitrifying bacteria and the like are supported by the floating carrier 11a, the nitrifying bacteria and the like are maintained at a high concentration without flowing out of the respective treatment sections 4b. Since the fluid flows due to the aeration and the chance of contact with the object to be treated increases, a biological reaction occurs efficiently.

When the water flow resistance of the filter medium layer 8 increases (or periodically), air is blown out from each air blow hole of the air pipe 9 to cause the filter medium to stir and flow.
Release solid material trapped between each filter media, or between the filter media,
Thereby, the blockage of the filter medium layer 7 is prevented.

According to the above-described structure, the filtered water 14 having a reduced solid substance load and organic substance load in the solid-liquid separation section A is allowed to flow into the biological treatment section B. In the biological treatment section B, denitrifying bacteria and nitrifying bacteria are used. Since the biological reaction occurs efficiently by supporting the carrier on a carrier, it is possible to obtain a water quality equal to or higher than that of the treatment using the floating activated sludge even with a smaller tank volume than the conventional method using the floating activated sludge. It is possible, and the processing time can be reduced.

More specifically, raw sewage is passed through a filter-filled solid-liquid separator constructed in the same manner as the solid-liquid separator A described above, whereby filtered water having a reduced solid and organic load is removed. In the case of biological treatment, when a floating carrier to which nitrifying bacteria are attached is used, as shown in FIG.
0 mgN / L-carrier · hr (carrier input rate 10% v / v)
When a fixed bed type carrier to which denitrifying bacteria were attached was used, the denitrification rate was 0.4 kgN / m, as shown in FIG.
It was confirmed that the ratio was about ³ packed beds / day (= 40 mg N / L packed bed / day).

From these facts, the nitrogen content of 30 mgN
/ L of the water to be treated is required to be 4
Approximately 5 hours, and at the beginning, an existing biological treatment tank designed to have a residence time in the tank of 6 to 8 hours assuming the standard activated sludge method has a margin in volume, so as described above, The volume was arranged in a section in front of the treatment tank, and it became possible to fill a filter medium to form a solid-liquid separation section.

Instead of the above-described embodiment, a downward flow path is formed in the treatment section 4b including the inflow port 4c, and a filter medium layer made of a filter medium having a specific gravity greater than the average specific gravity of the primary treated water is passed through the downward flow. It may be provided at the lower part of the road to form a solid-liquid separation part A,
Floating activated sludge may be used in the biological treatment section B. Further, the addition of the flocculant can be omitted.

[0035]

As described above, according to the present invention, even in an existing treatment plant, a part of an existing biological treatment tank is remodeled to provide a solid-liquid separation part filled with a filter medium, thereby providing an advanced treatment system. Can be introduced. At the time of treatment, first, coarse S
Since the primary treated water from which S has been removed is introduced into the solid-liquid separation section,
As compared with the case where a filter material-filled solid-liquid separation device is provided instead of the initial settling basin, the frequency of clogging is reduced, and the number of times of filtering material washing can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic overall configuration of a wastewater treatment apparatus according to an embodiment of the present invention.

FIG. 2 is a graph showing the nitrification characteristics of a conventional in-tank flow type nitrifying bacteria-adhering carrier used in the wastewater treatment apparatus of FIG.

FIG. 3 is a graph showing the denitrification characteristics of a conventional fixed-bed type denitrifying bacteria-adhered carrier used in the wastewater treatment apparatus of FIG.

FIG. 4 is an explanatory diagram showing a schematic overall configuration of a conventional wastewater treatment apparatus.

FIG. 5 is a graph showing the SS removal characteristics of a conventional solid-liquid separator filled with a filter medium.

[Explanation of symbols]

 2 First settling tank 3 Primary treatment water 4 Biological treatment tank 4a Partition wall 4c Inlet 6 Upflow channel 8 Filter media layer 9 Air piping 10 First denitrification unit 10a Fixed bed type carrier 11 Nitrification unit 11a Floating type carrier 12 First removal Nitrogen section 12a Fixed bed type carrier 13 Re-aeration section A Solid-liquid separation section B Biological treatment section

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01D 29/62 C02F 3/06 C02F 1/52 3/08 B 3/06 3/12 A 3/08 3/34 101D 3/12 B01D 29 / 08 520B 3/34 101 530C 540A 29/38 580A

Claims (6)

[Claims] A wastewater comprising a sedimentation basin for introducing wastewater and separating solids contained in the wastewater by gravity sedimentation, and a biological treatment tank for introducing and treating the primary treated water flowing out of the sedimentation basin for biological treatment. In the treatment apparatus, a part of the inflow portion in the biological treatment tank is separated by a partition wall, a filter material-filled layer is provided inside the partition wall, and the inside of the partition wall is formed as a solid-liquid separation portion. A wastewater treatment apparatus, wherein the inside of a tank on the downstream side is used as a biological treatment section. 2. A part from the inflow portion in the biological treatment tank is partitioned by a partition, and a supply means for supplying primary treated water inside and below the partition is provided, and the primary treated water flows upward inside the partition. An upward flow path is formed, and a filter medium filling layer is formed in the upward flow path by a filter medium having a specific gravity smaller than that of the primary treated water, and the inside of the upward flow path is formed as a solid-liquid separation section. The wastewater treatment device according to claim 1. 3. A coagulant injecting means for injecting an inorganic coagulant or a polymer coagulant in a flow path of the primary treatment water from the solid-liquid separation unit or the sedimentation tank to the solid-liquid separation unit. The wastewater treatment device according to any one of claims 1 and 2. 4. The wastewater treatment apparatus according to claim 1, wherein a washing means for washing by stirring and flowing the filter medium is provided inside the partition. 5. The wastewater treatment apparatus according to claim 1, wherein the biological treatment section has a carrier that carries a biofilm. 6. The wastewater treatment apparatus according to claim 5, wherein the biological treatment section is provided with a denitrification section and a nitrification section, and a floating type carrier carrying nitrifying bacteria is introduced into the nitrification section. .