JP2001047098A - Treatment of sewage and sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce not only the generation amt. of excessive sludge but also equipment cost and running cost 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. SOLUTION: A filter membrane unit 1A is arranged in a biological reaction tank 1 and an air diffuser 1C is arranged under the unit 1A and air is supplied to the air diffuser 1C from a blower 1B to perform aeration not only to bring the interior of the biological reaction tank 1 to an aerobic state but also to wash the filter membranes 1a constituting the filter membrane unit 1A. Ultrasonic transmitters 1D are arranged between the filter membranes 1a, and cell membranes of microorganisms forming sludge are destructed to solubilize sludge and the sludge bonded to the filter membranes 1a is shaken off. By this constitution, the clogging of the filter membranes 1a is made hard to generate and the filtering of treated water can be stably performed over a long time.

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 requires no sludge treatment equipment such as a sludge thickening tank 4 and has the advantage of reducing or eliminating the amount of excess sludge which has been a problem in the conventional treatment method. However, since the ozone reaction tower 14 is separately required, the effect of reducing the equipment cost 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.

The present invention has been made in view of the above-mentioned problems of the conventional methods for treating wastewater and sludge, and has the objective of improving the quality of treated water and reducing or eliminating the amount of excess sludge generated. It is another object of the present invention to provide a method for treating sewage and sludge, which can 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 first aspect of the present invention performs aerobic biological treatment in a method for treating sewage and sludge by biologically treating organic sewage. The filtration membrane unit installed in the biological reaction tank performs solid-liquid separation of treated water and sludge, and solubilizes sludge using ultrasonic waves.

In order to achieve the same object, a method for treating sewage and sludge according to the second aspect of the present invention is a method for treating sewage and sludge which biologically treats organic sewage in a biological reaction tank for performing aerobic biological treatment. Is characterized by performing a solid-liquid separation of treated water and sludge by a filtration membrane unit installed in the apparatus, and solubilizing the sludge using hydrogen peroxide.

The method for treating wastewater and sludge according to the first aspect of the present invention performs solid-liquid separation of treated water and sludge by a filtration membrane unit installed in a biological reaction tank for performing aerobic biological treatment.
By solubilizing sludge using ultrasonic waves,
The method for treating sewage and sludge of the second invention comprises a filtration membrane unit installed in a biological reaction tank that performs aerobic biological treatment.
By performing solid-liquid separation of the treated water and sludge and solubilizing the sludge using hydrogen peroxide, the quality of the treated water can be improved and the amount of excess sludge generated can be reduced or Can be zero.

In this case, the sludge can be solubilized in the biological reaction tank.

Thus, the equipment can be simplified and the equipment cost can be further reduced.

[0013] Further, the solubilization of sludge can be performed at a position near the filtration membrane of the filtration membrane unit installed in the biological reaction tank.

[0014] This makes it difficult for the filtration membrane constituting the filtration membrane unit to be clogged, so that the filtration of the treated water can be stably performed over a long period of time, and the filtration membrane unit is pulled out of the biological reaction tank. And the running cost can be further reduced.

[0015]

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 processing flow of the method for treating sewage and sludge of the present invention. In this embodiment, a filtration membrane unit 1A for filtering treated water subjected to biological treatment is installed in one biological reaction tank 1, and a filtration membrane unit 1A is provided.
A diffuser 1C is installed at a position below A, and a blower 1B
By supplying air to the air diffuser 1C from the air 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 1a constituting the filtration membrane unit 1A is washed. I have to.

In the filtration membrane unit 1A, a plate-like ultrasonic transmission device 1D is arranged between filtration membranes 1a provided one above another,
The cell membrane of microorganisms forming sludge by the ultrasonic waves emitted from the ultrasonic transmitter 1D (including organic matter such as sludge attached to the filtration membrane 1a which causes clogging of the filtration membrane 1a constituting the filtration membrane unit 1A) Of the filtration membrane unit 1A, and the sludge or the like attached to the filtration membrane 1a constituting the filtration membrane unit 1A is shaken off.

In the present embodiment, the plate-like ultrasonic transmission device 1D is arranged between the filtration membranes 1a provided on the filtration membrane unit 1A, but the ultrasonic transmission device is arranged. The installation position is not limited to the one in the present embodiment. For example, in addition to being disposed so as to surround the outer periphery of the filtration membrane unit 1A, an ultrasonic wave transmitting device is installed outside the biological reaction tank 1, and The extracted sludge may be solubilized by ultrasonic waves emitted from the ultrasonic transmitter, and then returned to the biological reaction tank 1. However, from the viewpoint of simplifying the equipment, the solubilization of sludge is
It is preferable to configure it to be performed within.

The treated water filtered in the filtration membrane unit 1A is discharged from the biological reaction tank 1 by the suction pump 1P.

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

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. At the same time, the cell membrane of microorganisms forming sludge (of the filtration membrane 1a constituting the filtration membrane unit 1A) is generated by ultrasonic waves emitted from the ultrasonic transmission device 1D disposed between the filtration membranes 1a of the filtration membrane unit 1A. (Including organic matter such as sludge adhering to the filtration membrane 1a which causes clogging), solubilization by destruction, and shake off sludge adhering to the filtration membrane 1a constituting the filtration membrane unit 1A. To

Thus, the treated water discharged from the biological reaction tank 1 passes through the filtration membrane unit 1A, so that fine sludge such as dead microorganisms is not mixed into the treated water. Specifically, the SS, COD, transparency, and the like can be improved, and the amount of excess sludge generated can be reduced or reduced to zero. In particular,
The ultrasonic wave generated by the ultrasonic transmitter 1D disposed between the filtration membranes 1a of the filtration membrane unit 1A causes the filtration membrane unit 1
A solubilization by destruction of organic substances such as sludge adhering to the filtration membrane 1a which causes clogging of the filtration membrane 1a constituting the filter membrane 1a, and the filtration membrane 1a constituting the filtration membrane unit 1A
Since the sludge and the like adhering to the filter are shaken off, clogging of the filtration membrane 1a constituting the filtration membrane unit 1A 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 1A from the biological reaction tank can be reduced, and the running cost can be reduced. Also,
The solubilization of sludge performed using ultrasonic waves has the advantage that there is no problem of excess ozone and the sewage treatment equipment can be simplified, unlike the case of solubilizing sludge using ozone.

Further, in this embodiment, since the filtration membrane unit 1A is installed in the biological reaction tank 1 for performing aerobic treatment, the time during which 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.

Further, the size of the ultrasonic wave emitted from the ultrasonic wave transmitting device 1D and the operation time of the ultrasonic wave transmitting device 1D can be adjusted so as to correspond to the amount of excess sludge generated in the biological reaction tank 1. This makes it possible to reduce the amount of surplus sludge to substantially zero.

The biological treatment of sewage requires an activated sludge concentration (MLSS) of 1000 times, which is nearly 10 times that of the standard activated sludge method.
It can be carried out by being installed at about 0 to 20000 mg / liter. By the way, in this activated sludge concentration range,
Although the processing activity of microorganisms is not impaired, it is possible to perform normal biological treatment of organic wastewater.However, in order to maintain the activated sludge concentration within a certain range, it is necessary to treat excess sludge at a certain rate. is there. Here, the amount of excess sludge generated can be reduced as the activated sludge concentration is increased and the sludge residence time in the biological reaction tank 1 is increased, so that the effect of the combination with the filtration membrane method can be produced. .

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.

FIG. 2 shows a second embodiment of the processing flow of the method for treating sewage and sludge of the present invention. In this embodiment, a filtration membrane unit 1A for filtering treated water subjected to biological treatment is installed in one biological reaction tank 1, and a filtration membrane unit 1A is provided.
A diffuser 1C is installed at a position below A, and a blower 1B
By supplying air to the air diffuser 1C from the air 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 1a constituting the filtration membrane unit 1A is washed. Is the same as in the first embodiment.

On the other hand, the generated sludge is withdrawn from the biological reaction tank 1 by the sludge pump 3 and sent to the reaction tower 21 as surplus sludge, where hydrogen peroxide introduced from the chemical tank 22 connected via the chemical pump 23 is supplied. After being solubilized by oxidative decomposition, the sludge is transferred into the biological treatment tank 1 by the sludge transfer pump 19. In this case, the reaction tower 21
Is provided with a stirrer 21A to sufficiently stir the excess sludge and hydrogen peroxide.

In the present embodiment, the reaction tower 21 is provided outside the biological reaction tank 1, and the sludge extracted from the biological reaction tank 1 is solubilized by oxidative decomposition with hydrogen peroxide in the reaction tower 21. Then, it is configured to be returned to the biological reaction tank 1, but the supply position of hydrogen peroxide is not limited to the one in the present embodiment. For example, the inside of the biological reaction tank 1, particularly, the filtration membrane unit 1A It may be located near the filtration membrane 1a. However, in order to eliminate the adverse effect of unreacted hydrogen peroxide, it is preferable to use the reaction tower 21 having a sufficient reaction time.

In the sewage treatment equipment configured as described above, the 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 1. In this case, by supplying air from the blower 1B to the air diffuser 1C 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. Also,
The generated sludge is withdrawn from the biological reaction tank 1 by the sludge pump 3 and sent to the reaction tower 21 as surplus sludge, where it is oxidatively decomposed by hydrogen peroxide introduced from the chemical tank 22 connected via the chemical pump 23. And then introduced into the biological treatment tank 1 by the sludge transfer pump 19.

Thus, the aerobic biological treatment of sewage in the biological reaction tank 1 in which the filtration membrane unit 1A is installed, and the solubilization of the sludge by oxidative decomposition in the reaction tower 21 can be performed independently of each other. Sludge can be treated efficiently. In addition, by performing solubilization by oxidative decomposition of sludge, organic matter such as sludge which causes clogging of the filtration membrane 1a constituting the filtration membrane unit 1A can be destroyed. Membrane 1
a becomes less likely to be clogged, and the filtration of the treated water can be stably performed over a long period of time. Further, the solubilization of sludge performed using hydrogen peroxide has the advantage that there is no problem of excess ozone and the sewage treatment facility can be simplified, unlike the case of solubilizing sludge using ozone.

The supply amount and supply time of hydrogen peroxide to the reaction tower 21 can be adjusted so as to correspond to the amount of excess sludge generated in the biological reaction tank 1, thereby generating excess sludge. The amount can be substantially zero. For this reason, for example, an activated sludge concentration meter is installed in the biological reaction tank 1, and when the concentration of the activated sludge in the biological reaction tank 1 reaches a predetermined value or more, excess sludge is withdrawn from the biological reaction tank 1, and this is withdrawn. The sludge is preferably solubilized by oxidative decomposition with hydrogen peroxide in the reaction tower 21 and then returned to the biological reaction tank 1,
To implement this, a control device (not shown) such as a timer for regulating the supply amount and supply time of hydrogen peroxide can be provided.

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

[0034]

The method for treating sewage and sludge of the first invention is as follows.
The filtration membrane unit installed in the biological reaction tank for performing aerobic biological treatment performs solid-liquid separation of treated water and sludge and solubilizes sludge using ultrasonic waves. The method of treating sewage and sludge is to perform solid-liquid separation of treated water and sludge using a filtration membrane unit installed in a biological reaction tank that performs aerobic biological treatment, and to solubilize the sludge using hydrogen peroxide. By doing so, the quality of the treated water can be improved, the amount of excess sludge generated can be reduced or eliminated, and the equipment cost and running cost can be reduced.

Further, by solubilizing the sludge in the biological reaction tank, the equipment can be simplified and the equipment cost can be further reduced.

Further, by solubilizing the sludge in the vicinity of the filtration membrane of the filtration membrane unit installed in the biological reaction tank, the filtration membrane constituting the filtration membrane unit is less likely to be clogged, and the treated water is prevented from being clogged. Filtration can be stably performed over a long period of time, and the number of washings performed by pulling up the filtration membrane unit from the biological reaction tank can be reduced, so that the running cost can be further reduced.

[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 1A Filtration membrane unit 1a Filtration membrane 1B Blower 1P Suction pump 1C Air diffuser 1D Ultrasonic wave transmitter 2 Sedimentation basin 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 Exhaust hopper 11 Compressor 12 Oxygen generator 13 Ozone generator 14 Ozone reaction tower 15 Exhaust ozone treatment device 16 Blower 17 Air diffuser 19 Sludge transfer pump 21 Reaction tower 21A Stirrer 22 Chemical liquid tank 23 Chemical liquid pump

Claims (4)

[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, characterized in that sludge is solubilized using ultrasonic waves. 2. A method for treating sewage and sludge, which biologically treats organic sewage, wherein 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. A method for treating sewage and sludge, comprising solubilizing sludge using hydrogen peroxide. 3. The method for treating wastewater and sludge according to claim 1, wherein the solubilization of the sludge is performed in a biological reaction tank. 4. The method for treating sewage and sludge according to claim 3, wherein the solubilization of the sludge is performed at a position near the filtration membrane of the filtration membrane unit installed in the biological reaction tank.