JP3154904B2 - How to rebuild sewage treatment facilities - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a method for renovating a sewage treatment facility by an activated sludge method comprising an aeration tank and a final settling pond.

[0002]

2. Description of the Related Art In cities where sewerage services have begun early, the number of treatment facilities that have been in service for more than 50 years has increased, and these treatment facilities have not only mechanical and electrical equipment but also civil engineering and construction facilities. Are also very old, causing an increase in maintenance costs. In addition, even in a sewage treatment plant with an age of 50 years or less, the demand for remodeling is increasing due to the need for advanced treatment or due to corrosion or the like.
Generally, when renovating an aging sewerage facility, it is important that the renovation work be carried out without impairing the function of the sewerage facility. During the renovation period, the replacement facilities are a problem, especially the replacement facilities in the sewage treatment facilities.

At present, the activated sludge method is mainly used as a water treatment method in a sewage treatment plant. FIG. 5 is a schematic sectional view of a main part of a sewage treatment plant by the activated sludge method, and shows a treatment system including a first settling tank P, an aeration tank AT, and a final settling tank F. In FIG. 5, the water to be treated first introduced into the sedimentation basin P from the pump station (not shown) via the distribution tank is:
Here, it is separated into a solid that relatively easily precipitates and supernatant water,
At the same time, scum floating on the water surface such as garbage and oil is also separated. The precipitated solid is pumped out of the pond bottom as sludge and sent to a sludge treatment facility. The residence time of the water to be treated in the first settling basin P is about 2 hours.

[0004] Air is fed into a water tank called an aeration tank AT (aeration tank), and adsorbs and decomposes pollutants in sewage using the action of aerobic microorganisms. The residence time of the water to be treated in the aeration tank AT is 6 to 8 hours. In the final sedimentation basin F, the mixed solution containing the microorganisms flowing out of the aeration tank AT is sedimented for about two hours, and the supernatant water is disinfected and discharged into a river or the like as treated water. Final sedimentation basin F
The sludge precipitated in the above contains many microorganisms, some of which are returned to the aeration tank AT as a group of microorganisms, and residual sludge is sent to a sludge treatment facility as surplus sludge.

[0005] Water treatment in the above-mentioned sewage treatment plants is usually operated in a plurality of systems. Therefore, if there is room in the capacity of these water treatment facilities, the sewage to be treated for one system is treated. Remodeling can be carried out one by one by allocating to other groups. In addition, if there is room in the site of the sewage treatment plant, an alternative facility can be installed at that site and the facility can be renovated. For example, if there is enough space for one settling pond at the beginning even if there is no room for one series, the existing processing series can be constructed by constructing one multi-layered processing facility above or below the ground. It is not impossible to dismantle and rebuild. However, the rebuilding method has a problem that the construction cost is extremely high and the maintenance and management cost such as pumping is also increased.

Therefore, especially when there is no room for both capacity and land, the above-mentioned method cannot be adopted, and a solution is awaited.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a sewage treatment facility having a plurality of treatment systems consisting of a first settling basin, an aeration tank and a final settling basin. The purpose is to provide a reasonable renovation method when there is no.

[0008]

[Constitution] In the present invention, the air supplied to the aeration tank is replaced with high-concentration oxygen, and the sewage is directly introduced into the aeration tank without first passing through the sedimentation basin, and the sewage treatment is carried out. It is characterized by constructing a facility, and then successively renovating facilities not used for sewage treatment while performing sewage treatment at the renovated facility.

[0009] Further, the present invention enhances the treatment capacity of aeration tanks other than the aeration tank to be reconstructed, and distributes the sewage treated in the aeration tank to the final sedimentation basin to perform sewage treatment, while the first settling basin in one series is being treated. Then, the aeration tank was rebuilt, and then the sewage treatment was performed at the renovated facilities, while facilities not used for sewage treatment were gradually rebuilt. As a method of increasing the treatment capacity of the aeration tank, a method of introducing immobilized microorganisms into the aeration tank or a method of introducing high-concentration oxygen into the aeration tank is desirable.

[0010] Further, the present invention provides a method wherein the air supplied to the aeration tank other than the aeration tank to be reconstructed is replaced with high-concentration oxygen, and the sewage is introduced directly into the aeration tank without first passing through the sedimentation tank. The sedimentation basin and the first sedimentation basin are separated for sewage treatment while sewage treatment is performed while a series of first sedimentation basin, aeration tank and final sedimentation basin are reconstructed. The feature is that the facilities that will not be provided will be gradually rebuilt.

[0011] The present invention also relates to a method for replacing air supplied to an aeration tank other than an aeration tank to be reconstructed with high-concentration oxygen and introducing sewage directly into the aeration tank without first passing through a sedimentation tank. The sedimentation basin, the first sedimentation basin are flowed in order, and the sewage treatment is carried out while the first settling basin, the aeration tank and the final sedimentation basin are reconstructed. It is characterized by rebuilding facilities that do not work sequentially.

[0012]

The treatment capacity of the aeration tank is promoted by introducing a high concentration of oxygen into the aeration tank or by introducing immobilized microorganisms. In addition, the separation and separation capacity of the final sedimentation basin is enhanced by devising the outflow route of the water to be treated discharged from the aeration tank. The aging facilities will be gradually rebuilt while securing the current processing capacity of the facilities. When the aging facility is reconstructed, the alternative treatment facility is dismantled and removed. Alternatively, the treatment capacity of the sewage treatment plant may be enhanced by making the treatment facility a permanent facility.

[0013]

FIG. 6 shows a typical layout of a sewage treatment plant using the standard activated sludge method. A treatment system consisting of a first settling tank P, an aeration tank AT and a final settling tank F is arranged in a plurality of rows in parallel. is set up. Hereinafter, the method of renovating the sewage treatment facility of the present invention will be described, taking as an example the case of renovating the three series of sewage treatment facilities.

FIG. 1 is a plan view showing a preferred embodiment of a rebuilding method according to the present invention. In this embodiment, an oxygen activated sludge method is used during a rebuilding operation.
FIG. 7 is a flow sheet of the oxygen activated sludge method, which is 90% to 90% instead of the air of the standard activated sludge method described above.
It uses oxygen at a high concentration of 95% and has the following features.

(1) With the aeration time of about 1/2 that of the standard activated sludge method, the same BOD, SS, COD and transparency of the water to be treated can be obtained as those of the standard activated sludge method. (2) MLSS (the amount of aerobic microorganisms in the aeration tank) can be maintained at least twice that of the standard activated sludge method, and BOD
BOD-S with a volumetric load of 1.0 to 2.0 kg / m ³ · day
It can be operated at an S load of 0.3 to 0.6 kg / SS kg / day. This means that the volume of the aeration tank can be made smaller than that of the standard activated sludge method, and can be reduced to about 1/3 if the same BOD is removed.

(3) Although it depends on water quality conditions, for example, in the case of a small-scale sewage treatment plant or the like, the sedimentation basin can be omitted first. (4) Since the sedimentation of sludge is good, the operation of the final sedimentation basin is easy. In addition, the amount of excess sludge generated is generally smaller than that of the standard activated sludge method. (5) If the aeration tank is of a closed type, the surrounding environment will not be impaired by bubbles and droplets, and the amount of exhaust gas will be small.
Since most of the odor gas is oxidized and decomposed, secondary pollution due to odor can be prevented.

First, as shown in FIG. 1A, the existing three series of aeration tanks AT are changed to oxygen type aeration tanks OAT. For that purpose, the oxygen generator OG and the stirrer M are required, but the structure of the aeration tank AT and the aeration pipe can be used as they are, which is economical. When the tank is closed in order to effectively use the supplied oxygen, the top of the oxygen-type aeration tank OAT is covered, a plurality of partitions are provided in the tank, and an exhaust gas extraction device is installed. By changing to the oxygen activated sludge method, it is not necessary to use the sedimentation basin P at first, so the sewage is introduced directly into the aeration tank OAT without passing through the sedimentation basin P first.

The place where the sedimentation basin P was initially provided, that is, the portion surrounded by the dashed line in FIG. 1 (a) is an empty space, and a single sewage treatment facility is constructed here. The facility to be constructed may be a facility to be installed as an alternative during the renovation work or a facility to be permanently installed.
In this example, a series of oxygen-type aeration tanks OAT and a final sedimentation basin F were constructed in order to construct a treatment facility by the oxygen-type activated sludge method (FIG. 1 (b)).

Next, as shown in FIG. 1 (c), while the sewage treatment is being performed at the reconstructed one-line facility, the aging facility which has been performing the sewage treatment (the part surrounded by the dashed line) ). In this way, the entire sewage treatment facility is renewed and reconstructed by successively renovating aging facilities (oxygen-type aeration tank OAT and final sedimentation basin F) while performing sewage treatment at the renovated facility. be able to.

In the present embodiment, the aging treatment facility based on the standard activated sludge method is remodeled into a treatment facility based on the oxygen activated sludge method. However, the sewage treatment facility after the renovation is not limited to this. Deep sludge treatment facility by activated sludge method, or treatment facility in which first settling basin, aeration tank and final settling basin are installed on the ground or underground in a multi-layered manner,
It may be a treatment facility utilizing immobilized microorganisms described below. However, the oxygen-type activated sludge method can be operated at a high load as described above, and requires a small site area. Therefore, the oxygen-type activated sludge method is an effective method for renovating a treatment plant where there is no room in capacity and land.

After renovating the aging three-line oxygen-type aeration tank OAT and final sedimentation basin F, the alternative treatment facility is dismantled and removed. This site can be used as a site or vacant land for other facilities. Of course, four lines may be constructed by making the treatment facility a permanent facility to increase the treatment capacity of the sewage treatment plant.

FIG. 2 is a plan view of a sewage treatment plant for explaining another embodiment of the present invention. In this embodiment, the processing capacity of two systems except for the first system to be reconstructed first is 1 By increasing it by a factor of five, the existing processing capacity will be provisionally secured without operating the renovation equipment.
For this reason, two of the existing aeration tanks AT are changed to an aeration tank AAT having an enhanced processing capacity, and the aeration tank AA
The water to be treated flowing out of T is appropriately distributed to the three final sedimentation basins F for sewage treatment. Here, as a method of promoting the processing capacity of the aeration tank AT, the method may be changed to the oxygen-type aeration tank, or may be performed by introducing immobilized microorganisms into the aeration tank.

In the present invention, the activated sludge method using immobilized microorganisms refers to a microorganism which adsorbs and decomposes organic pollutants in sewage, which is composed of polyacrylamide, polyvinyl alcohol, sand, activated carbon, silica gel, molecular sieve, alumina and the like. Insoluble carriers such as ceramics,
Immobilization by covalent bonding or physical adsorption (carrier binding method) or introducing the microorganisms in agar, calcium alginate, carrageenan, polyacrylamide, polyurethane, etc. (inclusive method) and introducing them into the aeration tank In this way, it refers to a method of promoting the processing capacity of the aeration tank.

In the present embodiment, facilities that are not used for sewage treatment while securing the current treatment capacity as described above (FIG. 2A)
In the area enclosed by the dashed line). FIG.
(B) shows that, in this part, one series of a treatment system consisting of the sedimentation basin P, the aeration tank AT and the final sedimentation basin F was constructed, and this treatment system was one series of 1.5 before the renovation. It has twice the processing capacity.

Next, as shown in FIG. 2 (b), the reconstructed one system (processing capacity: 1.5 times) and the existing one system (processing capacity: 1.5 times) are operated to perform the current processing. Work on renovating the remaining aging facilities (the area enclosed by the dashed line) while securing the capacity.

FIG. 2 (c) is a layout diagram of the treatment facility after the completion of the renovation. Two treatment facilities based on the standard activated sludge method, in which the treatment capacity of one treatment system has been increased to 1.5 times the conventional one, are constructed. As a result, the treatment plant has the same treatment capacity as before the renovation. In addition, the treatment facility after the renovation may be a treatment facility using an oxygen activated sludge method or an immobilized microorganism. In FIG. 3C, the space indicated by the dotted line is a vacant land, and can be used for an appropriate purpose.

FIG. 3 is a plan view of a sewage treatment plant for explaining another embodiment using the oxygen activated sludge method.
The point that the processing capacity of the existing system is increased by 1.5 times is the same as that of the embodiment shown in FIG. That is, the existing two series of aeration tanks AT were changed to oxygen-type aeration tanks OAT, and the mixed liquids were used as a method for enhancing the sedimentation / separation ability of a mixture containing microorganisms flowing out of the oxygen-type aeration tanks OAT. The water is divided into the final sedimentation basin F and the first sedimentation basin P in proportion to the water area of each facility. In this embodiment, the structures of the initial settling basin P and the final settling basin F are almost the same, and a current plate, a scum removing device,
Such an operation process was adopted because the ancillary facilities such as a sludge scraper were also common.

In the present embodiment, a facility not used for sewage treatment (a portion surrounded by a dashed line in FIG. 3) was reconstructed while operating the existing two systems that were increased 1.5 times, and thereafter, As in the previous example, the remaining aging facilities will be gradually rebuilt.

The embodiment shown in FIG. 4 is also an embodiment in which the treatment capacity is promoted by using the oxygen activated sludge method as in the embodiment shown in FIG. 3, and contains the microorganisms flowing out of the oxygen aeration tank OAT. The mixed liquid is passed through an existing final sedimentation basin F, and firstly flows in the order of the sedimentation basin P, to thereby separate and separate the mixture. Also in the present embodiment, the existing 2
Facilities that are not used for sewage treatment while operating the line (Fig. 4,
The area surrounded by the alternate long and short dash line) is renovated, and then the remaining deteriorated facilities are sequentially rebuilt in the same manner as in the above embodiment.

[0030]

According to the present invention, in a sewage treatment facility provided with a plurality of rows of treatment systems consisting of a first settling basin, an aeration tank and a final settling basin, there is no open space for a substitute facility, and the sewage treatment capacity is sufficient. Update of the facility,
Renovation is possible. In other words, there is no need to secure land for installing alternative facilities, and by gradually renovating the treatment line, existing aeration tanks and sedimentation basins can be used effectively, and workability and economy can be improved. Excellent in both properties and work period.

According to the first aspect of the present invention, since the aeration tank and the final sedimentation basin use the system before the renovation as it is and do not stop the operation of one of the processing facilities for the renovation work, Stable sewage treatment can be performed.

According to the second aspect of the present invention, it is only necessary to install piping equipment capable of appropriately distributing the water to be treated flowing out of the aeration tank having enhanced treatment capacity to a plurality of final sedimentation basins. It has an excellent effect of being easy and economical.

The invention described in claim 3 can be achieved only by introducing immobilized microorganisms having a low material cost into the aeration tank in order to promote the treatment capacity in the invention described in claim 2. In particular, it is excellent in workability, economy, and construction period.

The invention described in claim 4 adopts an oxygen-type activated sludge method which has been used as a high-efficiency treatment method in order to promote the treatment capacity in the invention described in claim 2. Extremely reliable.

According to the fifth aspect of the present invention, since a series of a sedimentation basin, an aeration tank, and a final sedimentation basin is set as a target facility for renovation, the renovation area is large, the construction is easy, and the construction is easy. Since the outflow water to be treated is separated in proportion to the water area of the final sedimentation basin and the first sedimentation basin, the sedimentation separation effect is high and stable treatment can be performed.

According to the sixth aspect of the present invention, similar to the fifth aspect of the present invention, the renovation area can be increased, and the piping system for flowing the water to be treated in the order from the final sedimentation basin to the first sedimentation basin. Only need to be installed, which is excellent in workability and economy.

[Brief description of the drawings]

FIG. 1 is a plan view showing a preferred embodiment of a rebuilding method according to the present invention.

FIG. 2 is a plan view of a sewage treatment facility showing another remodeling method of the present invention.

FIG. 3 is a plan view of a sewage treatment facility showing another embodiment using the oxygen activated sludge method.

FIG. 4 is a plan view of a sewage treatment plant showing another embodiment using an oxygen activated sludge method.

FIG. 5 is a sectional view of a main part of a sewage treatment plant by an activated sludge method.

FIG. 6 is a typical plan layout view of a sewage treatment facility by a standard activated sludge method.

FIG. 7 is a flow sheet of a typical oxygen activated sludge method.

[Explanation of symbols]

 P First settling tank AT Aeration tank OAT Oxygen type aeration tank AAT accelerated aeration tank F Final settling tank OG Oxygen generator M Stirrer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shizuo Sasaki 1043, Shimoyama, Onigakubo, Tsukuba, Ibaraki Pref. 1 Inside Kumagaya Gumi Technical Research Institute (72) Inventor Daijiro Tanabe 2nd Tsukudocho, Shinjuku-ku, Tokyo No. 1 Kumagaya Gumi Tokyo head office (72) Inventor Ryohei Ishida 1043 Shimoyama, Onigakubo, Tsukuba, Ibaraki Pref. 1 Kumagaya Gumi Co., Ltd. Technical Research Institute (56) References JP-A-61-138594 (JP) , A) JP-A-3-52694 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 1/00, 3/12

Claims (6)

(57) [Claims] In a method of renovating a sewage treatment facility having a plurality of treatment systems including a first settling tank, an aeration tank, and a final settling tank, air supplied to the aeration tank is replaced with high-concentration oxygen.
The sewage is first introduced into the aeration tank directly without passing through the sedimentation basin, and the sewage treatment is performed while the sewage treatment is performed while the renovation facility is constructed at the position of the first sedimentation basin. A method of rebuilding a sewage treatment facility, characterized by sequentially rebuilding facilities that will not be provided. 2. A method for rebuilding a sewage treatment facility having a plurality of treatment systems including a first settling tank, an aeration tank, and a final settling tank, wherein the processing capacity of an aeration tank other than the aeration tank to be remodeled is increased. While the sewage treated in the above is distributed to the final sedimentation basin and the sewage treatment is performed, the first sedimentation basin and the aeration tank of one series are reconstructed, and then the sewage treatment is performed in the renovated facility.
A method of rebuilding a sewage treatment facility characterized by sequentially rebuilding facilities that are not used for sewage treatment. 3. The method according to claim 2, wherein the treatment capacity of the aeration tank is increased by introducing immobilized microorganisms into the aeration tank. 4. The method according to claim 2, wherein the treatment capacity of the aeration tank is increased by introducing high-concentration oxygen into the aeration tank. 5. A method for rebuilding a sewage treatment facility having a plurality of rows of a treatment system including a first settling tank, an aeration tank and a final settling tank, wherein air supplied to an aeration tank other than the aeration tank to be remodeled has a high oxygen concentration. Instead, the sewage is directly introduced into the aeration tank without first passing through the sedimentation basin, and then divided into the final sedimentation basin and the first sedimentation basin for sewage treatment, while a series of first sedimentation basin, aeration tank and A method for rebuilding a sewage treatment facility, comprising rebuilding a final sedimentation basin, and then sequentially rebuilding facilities that are not used for sewage treatment while treating sewage at the renovated facilities. 6. A method of renovating a sewage treatment facility having a plurality of rows of a treatment system including a first settling tank, an aeration tank, and a final settling tank, wherein air supplied to an aeration tank other than the aeration tank to be reconstructed has a high oxygen concentration. Instead, the sewage is directly introduced into the aeration tank without first passing through the sedimentation basin, and then the final sedimentation basin, the first sedimentation basin are flowed in this order, and the sewage is treated. A method for rebuilding a sewage treatment facility, comprising rebuilding a sedimentation basin, and then sequentially rebuilding facilities that are not used for sewage treatment while treating sewage at the renovated facilities.