JP2001047082A - Treatment of sewage and sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the quality of treated water while reducing the generation amt. of excessive sludge by performing the solid-liquid separation of treated water and sludge by a filter membrane unit arranged in a biological reaction tank performing aerobic biological treatment and performing the solubilization of sludge by directly introducing ozone into the biological reaction tank. SOLUTION: A filter membrane unit 1A is arranged in a biological reaction tank 1 and an air diffuser 17 to which a compressor 11, an oxygen generator 12 and an ozone generator 13 are connected is arranged under the unit 1A. Ozone is supplied to the air diffuser 17 from the ozone generator 13 and air is directly diffused into the biological reaction tank 1 from a region below the filter membrane unit 1A to perform not only the solubilization of sludge by oxidative decomposition but also the washing of a filter membrane. The treated water filtered by the filter membrane unit 1A is discharged out of the biological reaction tank 1 by a suction pump 1P and the excessive ozone discharged from the biological reaction tank 1 is detoxified by a waste ozone treatment device 15 to be discharged to the atomospher by a blower 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for treating sewage and sludge, and more particularly to a method for treating sewage and sludge when biologically treating organic sewage by adding activated sludge to organic sewage such as sewage. Things.

[0002]

2. Description of the Related Art Conventionally, in the treatment of organic wastewater such as sewage,
From the viewpoints of the stability of treatment, the ease of maintenance and the like, and the like, an activated sludge method as shown in FIG. 3, in which activated sludge is added to organic wastewater to biologically treat the organic wastewater, is widely used. In this activated sludge method, organic wastewater is introduced into a biological reaction tank 1 for biological treatment, and then treated water containing sludge is introduced into a solid-liquid separation tank 2 such as a sedimentation pond, and the treated water and sludge are solidified. After performing liquid separation, the treated water is discharged into a river or the like after sterilization, and the sludge is partially returned to the biological treatment tank 1 as returned sludge by the sludge pump 3 and reused as activated sludge. The waste is sent to the sludge thickening tank 4 as surplus sludge, after it is concentrated, sent to the concentrated sludge storage tank 6 by the sludge transfer pump 5, sent to the sludge dewatering machine 8 by the sludge supply pump 7, and dewatered. , Is temporarily stored in a hopper 10 for discharging sludge via a conveying means 9 such as a belt conveyor and discharged.

In recent years, a filtration membrane method in which a filtration membrane unit 1A is installed in a biological reaction tank 1, as shown in FIG. 4, has been adopted in the activated sludge method. In this filtration membrane method, an organic wastewater is introduced into a biological reaction tank 1 in which a filtration membrane unit 1A is installed and subjected to biological treatment. Then, the treated water is passed through the filtration membrane unit 1A by a suction pump 1P and the biological reaction tank 1 is treated. From the biological reaction tank 1 by the sludge pump 3 and sent to the sludge thickening tank 4 as surplus sludge, where the sludge is concentrated.
And then sent to a sludge dewatering machine 8 by a sludge supply pump 7 and dewatered, then temporarily stored in a sludge hopper 10 via a conveyor means 9 such as a belt conveyor and discharged. I am trying to do it. In this case, an air diffuser 1C is installed below the filtration membrane unit 1A, and the blower 1B
By supplying air to the air diffusing device 1C from the above and performing aeration, the inside of the biological reaction tank 1 is brought into an aerobic state, and the filtration membrane constituting the filtration membrane unit 1A is washed.

The conventional activated sludge method is widely used because the treatment of organic wastewater can be performed stably and the maintenance and management can be easily performed. However, a large amount of excess sludge is generated, and the wastewater is disposed of. The method has been questioned. As shown in FIG. 5, an ozone method for solubilizing sludge using ozone to reduce the amount of excess sludge has been proposed. According to this ozone method, organic wastewater is introduced into a biological reaction tank 1 for biological treatment, and then treated water containing sludge is introduced into a solid-liquid separation tank 2 such as a sedimentation basin, so that the treated water and the solid-liquid After separation, treated water is discharged to rivers after sterilization,
The point that the sludge is returned to the biological treatment tank 1 as sludge by returning a part of the sludge by the sludge pump 3 and reused as activated sludge is as follows.
It is the same as the above-mentioned conventional activated sludge method. On the other hand, the excess sludge is sent to the ozone reactor 14 where the ozone generator 1 connected to the compressor 11 and the oxygen generator 12
After being solubilized by oxidative decomposition with ozone introduced from 3 through the air diffuser 17, it is introduced into the biological treatment tank 1 by the sludge transfer pump 19. The sludge that has been oxidatively decomposed and solubilized by the ozone is dissolved in the wastewater in the biological treatment tank 1 because the cell membrane of the microorganisms that form the sludge is destroyed, so that the amount of excess sludge generated is reduced or reduced to zero. can do. The surplus ozone released from the ozone reaction tank 14 is detoxified in the exhaust ozone treatment device 15 and then discharged to the atmosphere via the blower 16.

[0005]

By the way, in the above-mentioned filtration membrane method, a solid-liquid separation tank 2 such as a sedimentation tank is filtered by filtering treated water in the biological reaction tank 1 in the same amount as the inflow of organic wastewater. Compared with the case of using, it is possible to obtain high-quality treated water, to increase the concentration of activated sludge, to downsize the biological reaction tank 1, and to make the solid-liquid separation tank 2 such as a sedimentation tank unnecessary. In combination therewith, there is an advantage that the wastewater treatment equipment can be configured to be extremely compact and the amount of excess sludge generated can be reduced, but the amount of permeated water per filtration membrane area of the filtration membrane unit 1A is usually 0.5 to Since it is as small as about 1 m ³ / m ² / day, a large number of filtration membrane units 1A are required for filtration of the treated water, and it takes time and effort to wash the filtration membrane constituting the filtration membrane unit 1A. High cost There is a problem that phrase.

On the other hand, the ozone method eliminates the need for sludge treatment facilities such as the sludge concentration tank 4 and can reduce or eliminate the amount of excess sludge which has been a problem in the conventional treatment method. Although there are many advantages, such as decolorization, sterilization, and deodorization of the treated water, the ozone reaction tower 14 is separately required, so that the facility cost reduction effect is small,
In addition, microscopic sludge such as dead bodies of microorganisms is not sufficiently settled and separated in the solid-liquid separation tank 2 such as a sedimentation basin, and the quality of the treated water, specifically, SS, COD, transparency, and the like are deteriorated. There was a problem of doing.

[0007] In view of the above-mentioned problems of the conventional methods for treating wastewater and sludge, the present invention can improve the quality of treated water by combining the filtration membrane method with the ozone method, An object of the present invention is to provide a method for treating sewage and sludge that can reduce or eliminate the amount of generated sludge and can further reduce equipment costs and running costs.

[0008]

Means for Solving the Problems To achieve the above object, a method for treating sewage and sludge according to the present invention is a method for treating a wastewater and sludge by biologically treating organic sewage. The filtration membrane unit installed in the tank performs solid-liquid separation of treated water and sludge, and also directly introduces ozone into the biological reaction tank to solubilize sludge. Here, the term "biological reaction tank for performing aerobic biological treatment" refers to a biological reaction in which the inside of the biological reaction tank is aerobic by continuously or intermittently aerating and performing biological treatment of organic wastewater. Means tank.

In this method for treating sewage and sludge, a filtration membrane unit installed in a biological reaction tank for performing aerobic biological treatment performs solid-liquid separation of treated water and sludge, and directly converts ozone into the biological reaction tank. By introducing and solubilizing the sludge, the quality of the treated water can be improved, and the amount of excess sludge generated can be reduced or eliminated.

[0010] In this case, ozone can be introduced from below the filtration membrane unit.

As a result, clogging of the filtration membrane constituting the filtration membrane unit is less likely to occur, and the filtration of the treated water can be performed stably for a long time, and the filtration membrane unit is lifted from the biological reaction tank. And the number of cleanings performed by the cleaning can be reduced, and the running cost can be reduced.

Further, the inside of the biological reaction tank can be separated by a partition wall in a state in which sewage can flow, and a filtration membrane unit can be installed in one tank and ozone can be introduced into the other tank.

Thus, the aerobic biological treatment of the sewage is independently performed in one tank in which the filtration membrane unit is installed, and the solubilization by oxidative decomposition of the sludge is independently performed in the other tank into which ozone is introduced. Wastewater and sludge can be treated efficiently.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for treating sewage and sludge of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the method for treating sewage and sludge of the present invention. In this embodiment, a filtration membrane method and an ozone method are combined and implemented. In one biological reaction tank 1, a filtration membrane unit 1A for filtering biologically treated water is installed, and a filtration membrane is provided. The compressor 11 and the oxygen generator 12 are located below the unit 1A.
And an air diffuser 17 connected to the ozone generator 13 is provided. Ozone is supplied from the ozone generator 13 to the air diffuser 17, and the biological reaction tank is disposed below the filtration membrane unit 1 </ b> A installed in the biological reaction tank 1. By directly diffusing ozone into the inside 1, solubilization by oxidative decomposition of sludge (including organic matter such as sludge adhered to the filtration membrane which causes clogging of the filtration membrane constituting the filtration membrane unit 1 </ b> A) is prevented. At the same time, the filtration membrane constituting the filtration membrane unit 1A is washed.

The treated water filtered in the filtration membrane unit 1A is discharged from the biological reaction tank 1 by the suction pump 1P. Further, surplus ozone released from the biological reaction tank 1 is detoxified in the waste ozone treatment device 15 and then discharged to the atmosphere via the blower 16. Furthermore, in order to maintain the inside of the biological reaction tank 1 in an aerobic state, the biological reaction tank 1 is provided with an aeration device having an arbitrary configuration such as a blower 1B that directly supplies air to the diffuser 17. Can be.

In this case, the filtration membrane constituting the filtration membrane unit 1A has a pore diameter of 0.1 to 0.1 made of ceramic or the like which is not easily affected by oxidation by ozone or corrosion by sewage.
It is preferable to use an inorganic microfiltration membrane of about 0.4 μm.

In the sewage treatment equipment configured as described above, organic sewage is introduced into the biological reaction tank 1 in which the filtration membrane unit 1A is installed and biologically treated, and then the treated water is sucked through the filtration membrane unit 1A. It is discharged from the biological reaction tank 1 by the pump 1P. In this case, by supplying air from the blower 1B to the air diffuser 17 installed below the filtration membrane unit 1A and performing aeration, the inside of the biological reaction tank 1 is brought into an aerobic state, and the filtration membrane unit 1A is removed. The constituent filtration membrane is washed. Further, the air diffuser 17 is supplied with ozone from the ozone generator 13 in conjunction with the supply of air from the blower 1B or alternately with the supply of air, and the filtration membrane unit installed in the biological reaction tank 1 is provided. Sludge (including organic substances such as sludge attached to the filtration membrane that causes clogging of the filtration membrane constituting the filtration membrane unit 1A) by directly diffusing ozone into the biological reaction tank 1 from below the 1A. ) Is carried out by oxidative decomposition, and the filtration membrane constituting the filtration membrane unit 1A is washed.

Thus, the treated water discharged from the biological reaction tank 1 is treated with ozone by passing through the filtration membrane unit 1A so that fine sludge such as dead microorganisms is not mixed into the treated water. Decolorization, sterilization, and deodorization of water are performed, and the water quality, specifically, SS,
The COD, the degree of transparency, and the like can be improved, and the amount of excess sludge generated can be reduced or eliminated. In particular, by directly diffusing ozone into the biological reaction tank 1 from below the filtration membrane unit 1A, organic substances such as sludge adhering to the filtration membrane which cause clogging of the filtration membrane constituting the filtration membrane unit 1A. Of the filtration membrane constituting the filtration membrane unit 1A, and the filtration membrane constituting the filtration membrane unit 1A is not easily clogged. Can be stably performed over a long period of time, and the number of washings performed by pulling up the filtration membrane unit 1A from the biological reaction tank can be reduced, thereby reducing running costs.

Further, in this embodiment, since the filtration membrane unit 1A is installed in the biological reaction tank 1 for performing aerobic treatment, the time for which the sewage and sludge stay in the biological reaction tank 1 is long. Therefore, the treatment of sewage and sludge can be performed stably and reliably. In particular, the decomposition rate of sludge is higher in aerobic conditions than in anaerobic conditions. Can be further reduced.

In this case, the biological reaction tank 1 is
The amount of ozone diffused into the inside can be adjusted so as to correspond to the amount of excess sludge generated in the biological reaction tank 1, whereby the amount of excess sludge generated can be made substantially zero.

In the method for treating sewage and sludge of the present invention, since phosphorus cannot be discharged, sedimentation and separation can be achieved by adding a flocculant to the treated water discharged from the biological reaction tank 1. It is preferable to combine with a crystallization dephosphorization method.

Next, FIG. 2 shows a second embodiment of the method for treating sewage and sludge of the present invention. In this embodiment, as in the first embodiment, a filtration membrane method and an ozone method are used in combination. (In this embodiment, although not particularly limited, the partition wall 18
Although the sewage passage is provided above and below the sewage, it is also possible to provide a sewage passage on the side edge of the partition wall 18 or to provide a sewage passage such as a slit on the partition wall 18. it can. ), A filtration membrane unit 1A for filtering treated water subjected to biological treatment is installed in one tank R1, and an air diffuser 17 connected to the compressor 11, the oxygen generator 12, and the ozone generator 13 in the other tank R2. Is installed,
Ozone is supplied from the ozone generator 13 to the air diffuser 17, and the ozone is directly diffused into the biological reaction tank 1, so that the sludge is solubilized by oxidative decomposition.

In this case, an air diffuser 1C is installed below the filtration membrane unit 1A, and the air diffuser 1B is provided from the blower 1B.
By supplying air to C and performing aeration, the inside of one tank R1 of the biological reaction tank 1 is brought into an aerobic state, and the filtration membrane constituting the filtration membrane unit 1A is washed.

In the sewage treatment equipment configured as described above, organic sewage is introduced into the biological reaction tank 1 for biological treatment, and then the treated water is passed through the filtration membrane unit 1A by the suction pump 1P to the biological reaction tank. Discharge from one of the tanks R1. In this case, by supplying air from the blower 1B to the air diffuser 1C installed at a position below the filtration membrane unit 1A and performing aeration, the inside of the biological reaction tank 1 is brought into an aerobic state,
The filtration membrane constituting the filtration membrane unit 1A is washed. The air diffuser 17 includes an ozone generator 13.
Is supplied from the reactor, and the ozone is directly diffused into the other tank R2 of the biological reaction tank 1, so that the sludge is solubilized by oxidative decomposition.

Thus, the aerobic biological treatment of the sewage in one tank R1 of the biological reaction tank 1 in which the filtration membrane unit 1A is installed can be performed by the oxidative decomposition of sludge in the other tank R2 for introducing ozone. The solubilization can be performed independently of each other, so that efficient treatment of sewage and sludge can be performed.

The other structure and operation of the sewage treatment equipment are the same as those of the first embodiment.

[0028]

According to the method for treating sewage and sludge of the present invention, solid-liquid separation of treated water and sludge is performed by a filtration membrane unit installed in a biological reaction tank for performing aerobic biological treatment. By directly introducing ozone into the tank and solubilizing the sludge, the quality of the treated water can be improved, and the amount of excess sludge generated can be reduced or reduced to zero. Since the equipment cost and the running cost can be reduced, a double effect can be obtained as compared with the conventional filtration membrane method and the ozone method using ozone alone.

Further, by introducing ozone from below the filtration membrane unit, clogging of the filtration membrane constituting the filtration membrane unit is less likely to occur, and the filtration of the treated water can be performed stably for a long time. In addition to this, the number of washings performed by pulling up the filtration membrane unit from the biological reaction tank can be reduced, and the running cost can be reduced.

Further, the inside of the biological reaction tank is separated by a partition wall so that sewage can flow therethrough, a filtration membrane unit is installed in one of the tanks, and ozone is introduced into the other tank. In one tank where the unit is installed, aerobic biological treatment of sewage can be performed, and in the other tank into which ozone is introduced, solubilization by oxidative decomposition of sludge can be performed independently. Efficient processing can be performed.

[Brief description of the drawings]

FIG. 1 is a processing flowchart showing a first embodiment of a method for treating sewage and sludge of the present invention.

FIG. 2 is a process flowchart showing a second embodiment of the method for treating sewage and sludge of the present invention.

FIG. 3 is a processing flow chart of the activated sludge method.

FIG. 4 is a processing flowchart of a filtration membrane method.

FIG. 5 is a processing flowchart of an ozone method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Biological reaction tank R1 tank R2 tank 1A Filtration membrane unit 1B Blower 1C Air diffuser 1P Suction pump 2 Final sedimentation tank 3 Sludge pump 4 Sludge thickening tank 5 Sludge transfer pump 6 Thickened sludge storage tank 7 Sludge supply pump 8 Sludge dehydrator 9 Conveying means 10 Hopper for sludge discharge 11 Compressor 12 Oxygen generator 13 Ozone generator 14 Ozone reaction tower 15 Ozone treatment device 16 Blower 17 Air diffuser 18 Partition wall 19 Sludge transfer pump

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C02F 1/50 560 C02F 1/50 560H 1/78 1/78 (72) Inventor Koichi Mizuta Shimosakabe, Amagasaki City, Hyogo Prefecture 3-11-1, Hitachi Kiden Kogyo Co., Ltd. (72) Inventor Masao Matsuoka 3-11-1, Shimosakabe, Amagasaki City, Hyogo Prefecture 3-11-1 F-term (reference) in Hitachi Kiden Kogyo Co., Ltd. 4D028 AA01 AA03 AA08 AC01 BD07 BD17 BE01 BE02 4D050 AA15 AB03 AB04 AB06 AB07 AB20 AB47 BB01 BB02 CA16 CA17

Claims (3)

[Claims] In a method for treating sewage and sludge for biologically treating organic wastewater, a filtration membrane unit installed in a biological reaction tank for performing aerobic biological treatment performs solid-liquid separation of treated water and sludge, A method for treating sewage and sludge, comprising directly introducing ozone into the biological reaction tank to solubilize the sludge. 2. The method for treating sewage and sludge according to claim 1, wherein ozone is introduced from below the filtration membrane unit. 3. The biological reaction tank is separated by a partition wall in a state where sewage can flow therethrough, a filtration membrane unit is installed in one tank, and ozone is introduced into the other tank. The method for treating sewage and sludge according to claim 1.