JP2008114161A - Method and apparatus for treating waste water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for treating waste water, by which putrefaction of the sludge in a storage tank for storing the sludge separated at a waste water treatment step can be prevented and production of a bad smell can be prevented by a simple and compact constitution. <P>SOLUTION: In the apparatus for treating the waste water which has the storage tank 7 for storing the sludge separated at the waste water treatment step, an upper underwater pump 11 for discharging the sludge toward the bottom of the storage tank 7 is arranged in the vicinity of the inner peripheral wall of the storage tank 7 to circulate the sludge vertically in the storage tank 7 and uniformize the dissolved oxygen amount in the whole sludge in the storage tank 7 so that the putrefaction of the sludge is prevented and the production of scum and the bad smell is prevented even when the storage tank is the deep one having a small installation area. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wastewater treatment method and apparatus, and more particularly to a wastewater treatment method and apparatus having a step of storing sludge in a storage tank.

  Conventionally, as shown in FIG. 3, an adjustment tank 21 that receives wastewater, an aeration tank 22 that takes out the wastewater from the adjustment tank 21 and performs aeration treatment in the presence of activated sludge, and receives wastewater that has been treated in the aeration tank 22. In a wastewater treatment apparatus comprising a sedimentation tank 23 for separating sludge and treated water, the sludge taken out from the sedimentation tank 23 is fed to an aeration tank 22 and a sludge treatment apparatus 24, and wastewater is treated biochemically. The sludge surface scum taken into the sedimentation tank 23 is scraped and removed and treated by the sludge treatment device 24 (for example, see Patent Document 1).

  Also, in order to prevent the sludge from becoming anaerobic and decaying in the sludge concentration tank, the sludge is extracted from the bottom of the concentration tank with a sludge pump and aerated to return it to the supply tank to the concentration tank. What was made is known (for example, refer patent document 2).

In addition, in facilities that ferment sludge and produce compost, etc., a stirrer shaft and a diffuser pipe with a paddle attached to the bottom of the storage hopper that stores sludge are made anaerobic in the storage hopper. It is also known to prevent rot and odor from occurring (see, for example, Patent Document 3).
Japanese Patent No. 3167270 JP 2006-87970 A Japanese Patent No. 3582699

  However, as described in Patent Document 1, in the configuration in which the scum that floats on the surface in the wastewater treatment process is removed and processed, the generated scum is processed, so that the sludge is stored. Even if it is applied to the tank, there is a problem that it is impossible to prevent the sludge from rotting in the storage tank and the scum rising and generating a bad odor.

  In addition, as described in Patent Document 2, the configuration in which the sludge is pulled out from the bottom of the concentration tank with a sludge pump and air-sealed back to prevent the sludge from decaying is complicated and large. Therefore, there is a problem that the equipment cost increases and a large installation area is required. Further, the configuration described in Patent Document 3 also has a problem that the equipment cost increases because it is necessary to arrange a complicated device configuration at the bottom of the storage hopper.

  In view of the above-mentioned conventional problems, the present invention provides a wastewater treatment method and apparatus capable of preventing the sludge decay and odor generation in a storage tank for storing sludge separated from a wastewater treatment process with a simple and compact configuration. The purpose is to do.

  The wastewater treatment method of the present invention is a wastewater treatment method having a step of storing sludge separated from the wastewater treatment step in a storage tank, and a submersible pump disposed in the vicinity of the inner peripheral wall of the storage tank at the bottom of the storage tank. The sludge is sent out to circulate the sludge. In addition, when a storage tank is a square shape, it is suitable to arrange | position a submersible pump in the corner part.

  According to this configuration, in a state where the sludge separated from the wastewater treatment process is stored in the storage tank, the submersible pump disposed near the inner peripheral wall of the storage tank, particularly in the case of a rectangular shape, is operated. In addition, sludge with a relatively large amount of dissolved oxygen near the surface of the sludge in the storage tank flows toward the bottom of the storage tank, so even if the depth of the storage tank is deep, the sludge at the corner of the bottom The sludge throughout the storage tank is effectively circulated and the dissolved oxygen amount is made uniform throughout. Thus, even in a storage tank having a small installation plane area and a deep depth, the sludge in the entire storage tank can be prevented from being spoiled and the occurrence of scum and malodor can be prevented. Moreover, since it is only necessary to place a submersible pump in the storage tank, the equipment cost is low, and no additional installation space for the circulation device is required. This can be prevented with a compact configuration.

  In addition, when sludge is sent from the bottom of the storage tank upward by a submersible pump to cause turbulent flow in the sludge flow, the sludge flow becomes turbulent in the storage tank. The amount of dissolved oxygen in the sludge can be made more uniform overall, and the occurrence of scum can be more effectively prevented. As the submersible pump installed at the bottom of the tank, a pump with a discharge rate of 1.5 times or more than the submersible pump at the top of the tank is adopted, and it is arranged at the central part of the tank, so that the above action is more effective. It can be obtained reliably and is suitable.

  In addition, the wastewater treatment process separates the wastewater aerated in the presence of activated sludge in the biological treatment tank into sludge and treated water in the sedimentation tank, and sends the separated sludge to the biological treatment tank and the storage tank. In some cases, application of the above configuration is effective for storing separated sludge.

  In addition, the sludge stored in the storage tank is sequentially taken out to the aeration tank, the sludge in the aeration tank is taken out sequentially to be re-substrate, the re-substrate sludge is returned to the aeration tank and the wastewater treatment process, and the membrane is permeated in the aeration tank. When it has the sludge treatment process which returns permeate to a wastewater treatment process, the processing of the stored sludge can be performed effectively.

  The wastewater treatment apparatus of the present invention is a wastewater treatment apparatus having a storage tank for storing sludge separated from the wastewater treatment process, and sends the sludge to the bottom of the storage tank in the vicinity of the inner peripheral wall of the storage tank. And the submersible pump which circulates sludge is arrange | positioned, The effect | action can be show | played by implementing the said waste_water | drain processing method.

  In addition, if a submersible pump that sends sludge upwards is installed at the bottom of the storage tank, turbulent flow can be generated in the sludge flow in the storage tank, and the amount of dissolved oxygen in the sludge in the tank Can be made uniform overall, and the occurrence of scum can be more effectively prevented.

  In addition, the wastewater treatment process includes a biological treatment tank for aeration treatment of wastewater in the presence of activated sludge and a precipitation tank for receiving wastewater treated in the biological treatment tank and separating it into sludge and treated water. When the separated sludge is configured to be sent to the biological treatment tank and the storage tank, applying the above-described storage tank configuration is effective for storing the sludge.

  In addition, water is separated from the aeration tank by membrane permeation, a storage tank, an aeration tank that sequentially removes sludge from the storage tank and performs aeration treatment, a re-substrateing device that sequentially extracts sludge from the aeration tank and converts it into a re-substrate. When the sludge treatment process is configured in the membrane separator, the water separated by the membrane separator is returned to the wastewater treatment process, and the re-substrate sludge is stored in the aeration tank and wastewater treatment process. The treated sludge can be effectively processed.

  According to the wastewater treatment method and apparatus of the present invention, the sludge near the surface having a relatively large amount of dissolved oxygen flows toward the bottom of the storage tank by a submersible pump disposed in the vicinity of the inner peripheral wall of the storage tank. Therefore, the amount of dissolved oxygen in the sludge in the entire storage tank is made uniform throughout, and even in a storage tank with a small installation flat area and deep depth, the sludge in the entire storage tank is prevented from being spoiled and scum and odor Can be prevented and the submersible pump is simply arranged in the storage tank, so that the equipment cost can be reduced and the space can be saved.

  Hereinafter, an embodiment of the wastewater treatment method and apparatus of the present invention will be described with reference to FIGS. 1 and 2.

  In FIG. 1, reference numeral 1 denotes an adjustment tank into which drainage flows from a drainage source, and an aeration device 2 is disposed at the bottom thereof. The waste water stored in the adjustment tank 1 is supplied to the biological treatment tank 3 by a pump (not shown). The biological treatment tank 3 is provided with an oscillating microorganism carrier (not shown) that supports a microorganism-carrying fiber body that carries microorganisms for treating the waste water so that the microorganisms can be oscillated. The arranged aeration device 4 is arranged.

  The wastewater after being treated in the biological treatment tank 3 is sent to a sedimentation tank 5 by a pump (not shown), and activated sludge composed of microorganisms floating in the wastewater is settled and separated in this sedimentation tank 5 and purified. The treated water is discharged out of the system. Part of the activated sludge separated in the sedimentation tank 5 is returned to the biological treatment tank 3, and the remaining surplus sludge is fed to the sludge treatment section 6.

  The sludge treatment unit 6 includes a storage tank 7 that stores the activated sludge fed from the settling tank 5, an aeration tank 8 that is supplied with activated sludge that has overflowed a weir (not shown) from the storage tank 7, and an aeration A membrane separation device 9 that separates and extracts the water in the tank 8 and an ultrasonic sludge reduction device 10 as a re-substrate forming means for taking activated sludge from the aeration tank 8 to re-substrate and recirculating it to the aeration tank 8. I have.

  In order to secure a sufficient volume with a small installation area, the storage tank 7 is configured by a rectangular parallelepiped tank having a small flat area and a deep depth, and is fed from the sedimentation tank 5 as shown in FIG. The sludge flows into one corner of the storage tank 7. An upper submersible pump that sucks sludge near the liquid surface of the storage tank 7 and sends it toward the bottom at the top of the other three corners of the storage tank 7 and circulates the sludge up and down in the storage tank 7. 11 is disposed. In addition, a bottom submersible pump 12 that sucks sludge at the bottom and sends it upward is disposed at the center of the bottom of the storage tank 7. The bottom submersible pump 12 has a discharge amount 1.5 times or more that of the upper submersible pump 11. The upper submersible pump 11 has a suction port located 2 to 5 cm below the liquid level, and the bottom submersible pump 12 is arranged so that the suction port is located about 2 cm from the bottom of the tank.

  The aeration tank 8 is provided with an aeration device 12 at the bottom thereof, and the re-substrate sludge is decomposed into nitrogen and water by aerobic digestion with activated sludge. The water is separated and extracted by the membrane separation device 9, refluxed to the precipitation tank 5, and discharged outside the system through the precipitation tank 5. In addition, a part of the resubstrate sludge that is recirculated from the ultrasonic sludge reduction device 10 is recirculated to the biological treatment tank 3 and decomposed in the biological treatment tank 3.

  In the wastewater treatment apparatus having the above configuration, the wastewater discharged from the wastewater source is received by the adjustment tank 1 and aerated by the aeration apparatus 2. Next, the waste water is taken out from the adjustment tank 1 to the biological treatment tank 3 and aerated by the aeration apparatus 4 in the presence of activated sludge in the biological treatment tank 3, and the organic matter in the waste water is decomposed by the activated sludge. Thereafter, the treated wastewater and activated sludge are taken out into the sedimentation tank 5, separated into sludge and treated water in the sedimentation tank 5, the separated treated water is discharged out of the system, and a part of the separated sludge is biological treatment tank. The remaining excess sludge is sent to the storage tank 7 of the sludge treatment unit 6.

  The sludge sent from the waste water treatment process is stored in the storage tank 7. In this storage state, when the upper submersible pump 11 disposed at the upper corner of the storage tank 7 is operated, sludge having a relatively large amount of dissolved oxygen near the surface of the storage tank 7 is shown in FIG. As indicated by the extraction arrow, the fluid flows toward the bottom of the storage tank 7 and the sludge in the storage tank 7 is circulated up and down. In addition, when the bottom submersible pump 12 disposed in the center of the bottom of the storage tank 7 is activated, the sludge in the center of the bottom of the storage tank 7 flows upward, and the sludge in the storage tank 7 is The vertical circulation is strengthened, and a turbulent flow is generated by colliding with a part of the sludge flow flowing toward the bottom. As a result, even when the depth of the storage tank 7 is deep, the sludge at the corners of the bottom is also effectively flowed and uniformly made uniform, so that the entire sludge in the storage tank 7 is effectively circulated and When mixed, the amount of dissolved oxygen in the sludge is uniformized to the minimum amount of dissolved oxygen that does not kill the microorganisms. Thus, even if the storage tank 7 has a small installation area and a deep depth, the entire sludge in the storage tank 7 can be prevented from decaying and the occurrence of scum and odors can be prevented.

  The sludge in the storage tank 7 is sequentially taken out to the aeration tank 8. The sludge in the aeration tank 8 is sequentially taken out by the ultrasonic sludge reduction device 10 and converted into a re-substrate, and a part of the re-substrate converted sludge is returned to the biological treatment tank 3 in the waste water treatment process and the remainder is processed. It is returned to the aeration tank 8 and decomposed into nitrogen and water by aeration treatment. The decomposed water is separated by the membrane separation device 9, is refluxed to the precipitation tank 5 in the waste water treatment process, and is discharged out of the system as treated water from the precipitation tank 5. As described above, the sludge stored in the storage tank 7 is sequentially processed in the sludge treatment unit 6.

  According to this embodiment, even if it is the storage tank 7 with a small installation area and a deep depth as described above, it is possible to prevent the decay of sludge and prevent the occurrence of scum and odor, and the storage tank 7. Since only the bottom submersible pump 11 and the bottom submersible pump 12 need to be arranged in the inside, the equipment cost can be reduced and no additional installation space for the circulation device is required. Can be prevented with a simple and compact configuration.

  The wastewater treatment method and apparatus of the present invention is such that the sludge near the surface with a relatively large amount of dissolved oxygen flows toward the bottom of the storage tank by a submersible pump arranged in the vicinity of the inner peripheral wall of the storage tank. The amount of dissolved oxygen in the entire sludge tank is made uniform throughout, and even if the storage space is small and deep, the sludge in the whole reservoir is prevented from decaying and scum and odors are generated. This can be prevented, and since only the submersible pump is arranged in the storage tank, the equipment cost can be reduced and the space can be saved. Therefore, it can be suitably applied to various wastewater treatment facilities.

The block diagram of the waste water treatment equipment of one embodiment of the present invention. The schematic plan view of the storage tank of the embodiment. The block diagram of the waste water treatment apparatus of a prior art example.

Explanation of symbols

3 Biotreatment tank 5 Precipitation tank 7 Storage tank 8 Aeration tank 9 Membrane separation device 10 Ultrasonic sludge reduction device (re-substrateing device)
11 Upper submersible pump 12 Bottom submersible pump

Claims (8)

  In the wastewater treatment method having a step of storing the sludge separated from the wastewater treatment step in the storage tank, the sludge is sent to the bottom of the storage tank by a submersible pump disposed in the vicinity of the inner peripheral wall of the storage tank. A wastewater treatment method characterized by circulating water.   The wastewater treatment method according to claim 1, wherein sludge is sent out by a submersible pump from the bottom of the storage tank upward to generate turbulent flow in the sludge flow.   The wastewater treatment step is characterized in that wastewater aerated in the presence of activated sludge in a biological treatment tank is separated into sludge and treated water in a sedimentation tank, and the separated sludge is sent to the biological treatment tank and the storage tank. The wastewater treatment method according to claim 1 or 2.   The sludge stored in the storage tank is sequentially taken out to the aeration tank, the sludge from the aeration tank is taken out sequentially to be re-substrate, the re-substrate sludge is returned to the aeration tank and the wastewater treatment process, and the permeated water is permeated through the aeration tank. A wastewater treatment method according to any one of claims 1 to 2, further comprising a sludge treatment step for returning the wastewater to the wastewater treatment step.   In a wastewater treatment device equipped with a storage tank that stores sludge separated from the wastewater treatment process, an underwater pump that distributes sludge toward the bottom of the storage tank and circulates the sludge is arranged near the inner peripheral wall of the storage tank. Wastewater treatment equipment characterized by having been installed.   6. The waste water treatment apparatus according to claim 5, wherein a submersible pump for sending sludge upward is disposed at the bottom of the storage tank.   The wastewater treatment process is equipped with a biological treatment tank for aeration treatment of wastewater in the presence of activated sludge and a precipitation tank for receiving wastewater treated in the biological treatment tank and separating it into sludge and treated water. The wastewater treatment apparatus according to claim 5 or 6, wherein the sludge is configured to be sent to a biological treatment tank and a storage tank.   A storage tank, an aeration tank that sequentially removes sludge from the storage tank and performs aeration treatment, a re-substrateing device that sequentially extracts sludge from the aeration tank and converts it into a re-substrate, and membrane separation that separates water from the aeration tank by membrane permeation The apparatus has a sludge treatment process, wherein the water separated by the membrane separation device is returned to the wastewater treatment process, and the re-substrate sludge is returned to the aeration tank and the wastewater treatment process. The waste water treatment apparatus in any one of Claims 5-7.

Images