JP6030003B2 - Sewage treatment apparatus and sewage treatment method - Google Patents

Description

  The present invention relates to sewage treatment such as sewage and industrial wastewater. More specifically, during normal times, the present invention can quickly respond to fluctuations in the amount of influent water and pollution load, and can also be used for earthquakes, tsunamis, concentrated heavy rain, etc. The present invention relates to a sewage treatment apparatus and a sewage treatment method that can also be used as an emergency recovery measure for sewage treatment facilities that have malfunctioned due to disasters or abnormal weather.

Due to diversification of industrial activities and life cycles, the amount of discharged sewage and its water quality tend to fluctuate greatly. To prevent environmental pollution and water pollution in public water areas, such sewage fluctuations must be ensured. It is necessary to treat sewage.
Therefore, normally, in order to treat sewage stably and properly, a large sewage storage tank is installed, a sewage treatment device with a sufficient processing capacity is built, or an advanced treatment unit is introduced. We are trying to stabilize.

  On the other hand, in sewage treatment facilities that have become dysfunctional due to disasters or abnormal weather, sedimentation using civil engineering structures such as existing aquariums and ponds, even in situations where it is difficult to secure personnel, supplies and electricity immediately after the disaster Perform as much disinfection as possible (emergency measures), respond quickly to ensuring public health and reducing flood damage (emergency recovery), and return to “main restoration” for the purpose of preventing disasters again Although the extent and scale of disasters will vary greatly, the scales of sewage treatment facilities and sewage treatment methods will vary, and there will be various emergency measures and emergency recovery. Measures are taken as appropriate according to the circumstances.

  Establish a treatment policy that can be realized from the facilities that are expected to be restored immediately and the expected inflow of sewage when the existing tanks, various pipes, and power equipment can be restored. Based on this, a temporary sewage treatment apparatus is constructed, and sewage is treated until the complete recovery. In addition, if it is difficult to restore existing sewage treatment facility machinery and equipment, the existing sewage treatment equipment can be simply modified or the flow path changed to minimize the impact on the water system of the treated water discharge destination. Sewage treatment will be performed. As an example of remodeling, there is a case where a contact filter medium is installed in a water tank, aerated, and a pollutant is simply processed.

  As a contact oxidation method performed by installing a contact filter medium in a water tank, a water purification channel including a biological filter bed having a biofilm carrier as a contact filter medium and an air supply unit is formed in an annular shape, and the water purification channel The biological filter bed type water purification method that changes the flow path of the liquid flowing in the water purification flow path by changing the inflow position of the treated raw water sequentially and changing the discharge position of the purified water in accordance with the change of the inflow position of the treated raw water And an apparatus are known (see paragraphs 0019 to 0024 of Patent Document 1). According to this water purification method, the biofilm growing on the contact filter medium is unlikely to be clogged, and the water purification effect is unlikely to decrease.

  However, even if the water purification apparatus and method described in Patent Document 1 are used as countermeasures for large load fluctuations and emergency recovery, for example, the pretreatment of sewage is insufficient, and the sewage flows into the biological reaction tank and the residue remains. If it is contained in a large amount (the suspended matter concentration is high), the residue will get entangled with the contact filter medium, causing clogging, or clogging (the residue will adhere to the filter medium and increase the thickness of the biofilm, However, there is a possibility that it will not be able to sufficiently cope with this, and it is difficult to perform stable sewage treatment.

JP 2002-102875 A (paragraph [0019] to paragraph [0024])

  Installation of large sewage storage tanks, construction of sewage treatment equipment with sufficient processing capacity, and advanced treatment units to treat sewage stably and properly in response to large fluctuations in sewage inflow and pollution load Thus, the sewage treatment can be performed stably. However, in that case, not only will the cost and energy consumption increase, such as an increase in the size of the sewage treatment device, an increase in the installation area, and an increase in construction costs and operation costs, but also maintenance work and maintenance inspection work will become complicated. As a result, there was a problem of going against efficient wastewater treatment such as resource saving and energy saving.

  For example, when dealing with a sudden increase in the amount of pollution load during normal times or at the site of emergency recovery after a disaster, a sufficient amount of sludge (seed) for stable biological treatment of the sewage treatment equipment and start of operation (startup) Since it is difficult to obtain (sludge) rapidly, there is a problem that it is necessary to quickly stabilize the treatment function of the biological reaction tank with the limited amount of sludge (seed sludge).

  In addition, when performing sewage treatment using filter media for emergency recovery, if pretreatment such as removal of residue contained in sewage is not sufficient, and the concentration of suspended (floating) substances in sewage is high, Clogging is likely to occur in the filter medium, and this clogging increases with time. Sufficient oxygen does not reach the biofilm, and anaerobic progress inside the biofilm (corruption) impedes aerobic biotreatment of sewage. I will give you. And if wastewater was short-circuited and discharged without being sufficiently treated, there was a problem that the quality of treated water deteriorated and water quality of the discharge destination water area was caused. In addition, in order to prevent the filter medium from being clogged, the filter medium installed under the surface of the water cannot be confirmed from the outside even when the filter medium is air-washed. There was a problem that the filter medium could not be washed.

  Even during normal times and in emergency recovery after a disaster, generally, among the filter media installed in the biological reaction tank, the upstream side into which sewage flows increases the amount of biofilm attached and the treated water flows out. Those on the downstream side tend to have less biofilm adhesion. For this reason, there existed a subject that all the filter media installed in the biological reaction tank were difficult to use uniformly and effectively. In addition, for example, when dealing with a sudden increase in the amount of pollution load during normal times or at the site of emergency recovery after a disaster, it is difficult to dispose of excess or newly generated sludge from the sewage treatment equipment. It is necessary to treat sewage while reducing the volume as much as possible, and also to quickly restore and stabilize the treatment function of the sewage treatment equipment that has malfunctioned, so that the quality of the treated water deteriorates and the water pollution of the discharge destination water area There was a problem that it was necessary to minimize the above.

  The present invention has been made to solve the above-described problems. In normal times, the present invention can quickly respond to fluctuations in the amount of inflow water and pollutant load, and can also respond to disasters such as earthquakes, tsunamis, and heavy rains. Another object of the present invention is to provide a sewage treatment apparatus and a sewage treatment method that can be used as an emergency recovery measure for a sewage treatment facility that has malfunctioned due to abnormal weather.

  The sewage treatment apparatus according to the present invention includes a biological reaction tank that introduces sewage to treat aerobic organisms, a solid-liquid separation facility that separates the liquid mixture of the biological reaction tank into treated water and separated sludge, A sludge return pipe for returning the separated sludge to the biological reaction tank, and a filter medium provided with one or two or more string-like filter media having trunk yarns and branch yarns in the biological reaction vessel. A module and a diffuser provided below the filter medium module are provided.

  The sewage treatment apparatus according to the present invention is characterized by comprising a scum removal facility for removing scum contained in the sewage.

  In the sewage treatment apparatus according to the present invention, the biological reaction tank is provided with a plurality of sewage inlets.

  In the sewage treatment apparatus according to the present invention, the solid-liquid separation facility includes a water tank, a plurality of separation blades arranged with a gap, a rotating cylinder into which the mixed liquid flows, and a rotating cylinder. It is a rotating cylindrical solid-liquid separation tank provided with a driving machine and a sludge scraper that scrapes the settled separated sludge.

  In the sewage treatment method according to the present invention, one or two or more filter media modules in which a plurality of string-like filter media having trunk yarns and branch yarns are arranged are provided in a biological reaction tank, and sewage is introduced into the biological reaction tank, Aerobic biological treatment is performed by aerating from below the filter medium module, and the mixed liquid flowing out from the biological reaction tank is solid-liquid separated into treated water and separated sludge, and a part or all of the separated sludge is removed from the biological organism. It returns to a reaction tank, It is characterized by the above-mentioned.

According to the sewage treatment apparatus according to the present invention, a biological reaction tank that introduces sewage and performs aerobic biological treatment, and a solid-liquid separation facility that separates the liquid mixture of the biological reaction tank into treated water and separated sludge; A sludge return pipe for returning the separated sludge to the biological reaction tank, and a filter medium provided with one or two or more string-like filter media having trunk yarns and branch yarns in the biological reaction vessel. Since it was set as the structure containing the module and the diffuser provided in the downward direction of this filter medium module, there exist the following outstanding effects.
(1) The string-like filter media that make up the filter media module are used in biological reaction tanks that perform aerobic biological treatment such as activated sludge treatment, by the inflow of sewage and the supply of air from diffusers (such as diffusers and diffusers). It moves softly due to the flow in the bioreactor that is generated, and the sewage efficiently contacts the biofilm that adheres and grows on the string-like filter material by flexibly swinging up and down and left and right with the branch thread connecting to the trunk thread as a fulcrum. In addition, the aerobic biological treatment is surely promoted under aerobic conditions. As a result, the treatment capacity of the sewage treatment apparatus can be further increased, so that the sewage treatment apparatus does not need to be increased in size or sophistication, and the associated costs such as construction costs and operation costs, and increase in energy consumption. It can be avoided.
(2) On the other hand, air is supplied into a biological reaction tank that performs aerobic biological treatment such as activated sludge treatment by an air diffuser, and an upward flow is generated in the biological reaction tank by the rise of the air bubbles, and string Oxygen necessary for the oxidative decomposition of the pollutant can be reliably supplied to the biofilm adhered and grown on the filter medium. In addition, the biofilm attached and grown on the string-like filter medium is enlarged with the aerobic biological treatment, but the biofilm is caused by the upward flow in the biological reaction tank, the swaying movement of the branch yarn, the collision of bubbles, etc. Can be peeled off, filter material blockage and biofilm surface area reduction can be prevented, and efficient aerobic biological treatment becomes possible.
(3) When sewage with a high suspended (floating) substance concentration is introduced into the bioreactor due to excessive slag contained in sewage or insufficient scum removal during pretreatment, Since the fibrous material that is hardly decomposed from the residue is entangled with the filter medium, there is a possibility that the filter medium is clogged relatively easily. However, as described above, the string-like filter medium can be easily eliminated by being swayed by the flow in the biological reaction tank or by air bubbles colliding with each other. Even if a serious blockage or the like occurs, the filter medium module itself can be pulled up, the blockage portion of the string-like filter medium can be appropriately checked, and necessary cleaning (peeling operation or the like) can be performed. This makes it possible to eliminate clogging of the filter medium, suppress biofilm enlargement, secure a biofilm surface area, etc., hold the biofilm properly, and supply oxygen sufficiently, so that it is stable and efficient in the bioreactor. Aerobic biological treatment can be maintained.
(4) By pulling up the filter media module, the degree of biofilm adhesion for each filter media module can be confirmed, and based on the degree of adhesion, air cleaning conditions (amount of cleaning air, frequency of cleaning) can be easily set for each filter media module. Therefore, the aerobic biological treatment of sewage can be performed efficiently and accurately.
(5) By replacing the filter medium module between the upstream side and the downstream side, the string-shaped filter medium with a large amount of biofilm attached to the upstream filter medium module is moved to the downstream side. All the string-shaped filter media installed in the biological reaction tank are used uniformly and effectively by transferring the string-shaped filter media with a small amount of biofilm attached to the upstream side of the filter medium module. The aerobic biological treatment in the entire reaction tank can be performed uniformly.

According to the sewage treatment apparatus according to the present invention, one or two filter medium modules in which a plurality of string-like filter media having trunk yarns and branch yarns are disposed in a biological reaction tank that performs aerobic biological treatment such as activated sludge treatment. Since it was set as the structure provided above, there exist the following outstanding effects.
(1) Since one or more filter media modules with multiple string-like filter media capable of securing a large surface area are provided, the amount of biofilm deposited and growing on the filter media surface is increased. Since the aerobic biological treatment under the aerobic condition by the aeration from the air vessel can be promoted, the treatment capacity of the sewage treatment apparatus can be further enhanced.
(2) A biofilm that adheres and grows on a string-shaped filter medium with a large surface area can always retain activated sludge organisms that are responsible for aerobic biological treatment of sewage, so the amount of sludge that is returned from the solid-liquid separation facility during normal times It is possible to reduce the MLSS (floating sludge concentration) of the biological reaction tank and to operate with a reduced amount of air, and to reduce the operation cost and maintenance work.
When the pollution (organic matter) load is extremely reduced, not only the operation cost and maintenance work can be reduced, but also activated sludge organisms, etc. by stopping the sludge return from the solid-liquid separation facility. Can survive. Conversely, when the pollution (organic matter) load is extremely increased, the amount of sludge returned from the solid-liquid separation facility can be increased and the MLSS of the biological reaction tank can be quickly increased. Aerobic biological treatment can be performed.
(3) Also, if it is not an extreme load fluctuation, for example, in a sewage treatment facility in an area that has a tourist spot, the sewage treatment is performed at the maximum sludge return amount during the peak load period, and sludge return during the transition period. The amount of wastewater can be reduced stepwise, and sludge return can be completely stopped in the off-season and the wastewater can be treated by catalytic oxidation. And since it is possible to quickly perform such operation according to the pollutant load by simple adjustment of sludge return amount, etc., it flows even at the time of disaster recovery or abnormal weather (such as heavy rain flood) Appropriate treatment can be promptly performed according to the quality and quantity of sewage.
(4) At the start of operation (startup) of the sewage treatment equipment, activated sludge (seed sludge) essential for aerobic biological treatment is introduced into the biological reaction tank to stabilize the biological reaction tank treatment function early. However, it is very difficult to obtain a sufficient amount of seed sludge necessary for quick start-up after the disaster. Even in such a case, the separation sludge separated by the solid-liquid separation facility can be immediately returned to the biological reaction tank through the sludge return pipe, so that the processing capacity of the biological reaction tank can be stabilized at an early stage even after a disaster. it can. In addition, the treatment capacity can be increased according to the quantity and quality of sewage that is expected to change as the disaster area recovers.

According to the sewage treatment apparatus according to the present invention, since the sewage contained in the sewage is removed and the sewage removal equipment is provided, the following excellent effects are obtained.
If sewage contains a lot of hair or fiber residue, or if solid-liquid separation is insufficient during pretreatment, the residue will flow into the biological reaction tank in large quantities. The filter media module and string-like filter media installed inside cause taintage, and further, the entanglement of the string-like filter media branches and the biofilm adheres and grows around the residue. In some cases, the entire string-like filter medium is covered with a biofilm and becomes a single columnar shape, which causes a serious hindrance to the aerobic biological treatment, resulting in a processing malfunction.
Therefore, in order not to fall into such a situation, a debris removal facility is provided, the debris is sufficiently removed from the sewage in advance, and the sewage from which the scum has been removed is allowed to flow into the biological reaction tank. Thereby, while being able to hold | maintain a string-like filter medium in a favorable state, the reduction | decrease of a biofilm area can be suppressed and a processing function can fully be exhibited. In addition, it is possible to prevent the clogging of the pipe line by removing the residue reliably, and also to suppress the increase in the amount of sludge generated due to the residue, thus maintaining the entire wastewater treatment apparatus well. can do.

According to the sewage treatment apparatus according to the present invention, the biological reaction tank includes a plurality of sewage inlets, and preferably includes a plurality of sewage inlets from upstream to downstream of the biological reaction tank. Excellent operational effects.
As described above, in the biological reaction tank, the amount of the biofilm attached to the string-like filter medium usually increases on the upstream side where sewage flows in, and on the downstream side where the biological reaction tank mixed liquid (mixed liquid) flows out. It tends to decrease. That is, the amount of adhesion (growth) is large when the pollution (organic matter) load is high, and small when the load is low. Therefore, by appropriately flowing in sewage from multiple sewage inlets, the pollution load can be leveled, and the bias of the amount of biofilm attached to the string-like filter medium can be easily controlled depending on the installation location. Become.
For example, by introducing a part of sewage with high pollution (organic matter) load into the downstream side of the biological reaction tank (such as an intermediate point of the biological reaction tank), the pollution (organic matter) load on the upstream side is reduced. It is possible to increase the pollution (organic matter) load on the downstream side and promote the growth of the biofilm adhering to the string filter medium on the downstream side, and thereby the amount of biofilm attached to the string filter medium in the bioreactor Therefore, it is possible to increase the processing efficiency of the entire biological reaction tank by effectively using all the string-like filter media. In addition, when the pollution (organic matter) load is low, it is possible to apply a small amount of organic matter to all the filter media modules from the upstream side to the downstream side, preventing the dismantling phenomenon due to the continuous low pollution load. Can maintain the biofilm.
In addition, you may let sewage flow in stepwise (for example, for every division provided in the biological reaction tank) of a biological reaction tank (step inflow).

According to the sewage treatment apparatus according to the present invention, a solid-liquid separation facility includes a water tank, a plurality of separation blades arranged with a gap, a rotating cylinder into which a mixed liquid flows, and the rotating cylinder being rotated. Since it is a rotating cylindrical solid-liquid separation tank equipped with a driving machine and a sludge scraping machine that scrapes the settled separated sludge, the following excellent effects are obtained.
(1) The mixed liquid that has flowed into the rotating rotating cylinder can be separated into treated water and separated sludge more quickly than ordinary gravity sedimentation, and fine sludge flocs that easily flow out along with the treated water are also captured. It is also possible to obtain clear treated water.
(2) In addition, since solid-liquid separation can be performed efficiently, separated sludge can be obtained reliably, the sludge concentration can be increased, and the amount of sludge to be treated or carried out of the field can be reduced.
(3) In the sewage treatment equipment, if the load of pollutant is constant, the amount of separated sludge (weight) generated is almost constant. If the amount of separated sludge is constant, the separated sludge capacity (volume) decreases as the concentration of separated sludge increases, and the labor, energy, and cost for processing and transport required for sludge treatment and unloading disposal are reduced.

According to the sewage treatment method of the present invention, sewage is introduced into a biological reaction tank provided with one or more filter media modules in which a plurality of string-like filter media having trunk yarns and branch yarns are arranged, and the filter media module. Aerobic biological treatment by aeration from below, solid-liquid separation of the mixed liquid flowing out from the biological reaction tank into treated water and separated sludge, and a part or all of the separated sludge to the biological reaction tank Since it is configured to be returned, the following excellent effects are obtained.
(1) Since a biofilm is formed on the string-like filter medium and the activated sludge organisms responsible for aerobic biological treatment of sewage are always retained, the amount of sludge returned from the solid-liquid separation facility is suppressed during normal times. The MLSS in the reaction tank can be lowered and operated with a reduced amount of air, reducing operating costs and maintenance work. When the pollution (organic matter) load is extremely reduced, solid-liquid separation is possible. By stopping the return of sludge from the facility and operating it, not only can operational costs and maintenance work be further reduced, but also activated sludge organisms can survive, and on the contrary, the pollution (organic matter) load is extreme. In such cases, the amount of sludge returned from the solid-liquid separation facility can be increased, and the MLSS of the biological reaction tank can be quickly increased, so that stable aerobic biological treatment of sewage can be performed. .
(2) A biofilm is formed on the string-like filter medium, and the separated sludge separated by solid-liquid separation is returned, so that the activated sludge organisms responsible for aerobic biological treatment of sewage can always be retained in the biological reaction tank. Therefore, even during emergency recovery due to a disaster or abnormal weather, a stable processing function can be quickly exhibited (recovered).

  As described above, the sewage treatment apparatus and the sewage treatment method according to the present invention are both prompt in the normal times even if the amount of water such as sewage or industrial wastewater flowing into the sewage treatment facility or the amount of pollution load fluctuates. It can also be used as an emergency recovery measure for sewage treatment facilities that have malfunctioned due to disasters such as earthquakes, tsunamis, torrential rains, and abnormal weather, so that they can be released during normal times and in times of disaster. Since it is possible to obtain treated water that matches the previous water quality, it is very effective for environmental conservation and prevention of water pollution in the water area of the treated water discharge destination.

It is a fragmentary sectional view which shows the whole structure of the sewage treatment apparatus by Embodiment 1 of this invention. It is a fragmentary sectional view which expands and shows the biological reaction tank of the sewage treatment apparatus shown in FIG. It is sectional drawing to which one form of the filter medium which comprises the filter medium module shown in FIG. 2 was expanded. It is a fragmentary sectional view which shows that the filter media module shown in FIG. 2 can be pulled up. It is a front view which shows that the installation place of the filter medium module shown in FIG. 2 can be changed. It is a fragmentary sectional view which shows the whole structure of the sewage treatment apparatus by Embodiment 2 of this invention. It is a fragmentary sectional view which shows the whole structure of the sewage treatment apparatus by Embodiment 3 of this invention. (A) is sectional drawing which shows the external structure of the rotary screen type | mold residue removal machine 20, (b) is sectional drawing which shows the external structure of the screen type | mold residue removal machine 21. FIG. It concerns on the sewage treatment apparatus by Embodiment 4 of this invention, (a), (b) and (c) are sectional drawings which show the example of installation of the filter medium module and a diffuser in a biological reaction tank. It is a fragmentary sectional view which shows the whole structure of the sewage treatment apparatus by Embodiment 5 of this invention. It concerns on the sewage treatment apparatus by Embodiment 5 of this invention, (a) is a front view which shows the external structure of a rotation cylinder, (b) is an AA arrow line view of (a), (c) These are sectional drawings which show the whole structure of the rotation cylinder type solid-liquid separation tank shown to (a) and (b). It is the graph which showed the time-dependent change of the BOD removal rate in Example 1, a CODMn removal rate, and SS removal rate regarding the removal of the main pollution parameter | index of sewage. It is the graph which showed the time-dependent change of the BOD removal rate, the CODMn removal rate, and SS removal rate in Example 2 regarding the removal of the main pollution parameter | index of sewage. It is the graph which showed the time-dependent change of MLSS (floating sludge density | concentration) in the biological reaction tank of Example 3 by the change of a sludge return rate. It is the graph which showed the time-dependent change of the separation sludge density | concentration of Example 4 by having installed the rotation cylinder type solid-liquid separation tank and the precipitation separation tank as a solid-liquid separation equipment. It is a photograph which shows the example of installation (shape) of a string-like filter medium.

Embodiment 1 FIG.
1 is a partial cross-sectional view showing the overall configuration of a sewage treatment apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a partial cross-sectional view showing an enlarged biological reaction tank of the sewage treatment apparatus shown in FIG. 3 is an enlarged cross-sectional view showing an embodiment of the filter medium constituting the filter medium module shown in FIG. 2, and FIG. 4 is a partial cross-sectional view showing that the filter medium module shown in FIG. 2 can be pulled up. 5 is a front view showing that the installation location of the filter medium module shown in FIG. 2 can be changed, and FIG. 16 is a photograph showing an example of installation (shape) of a string-like filter medium.
The
The sewage treatment apparatus according to the first embodiment includes a biological reaction tank 1 for treating an inflowing sewage with an aerobic biological treatment such as activated sludge treatment, a plurality of filter media modules 2 disposed below the surface of the biological reaction tank 1, A diffuser 3a provided below the filter medium module 2, a precipitation separation tank 4 (solid-liquid separation equipment) for solid-liquid separation of the mixed liquid from the biological reaction tank 1 into treated water and separated sludge, and the separated sludge as biological A sludge return pipe 9 that is returned to the reaction tank 1 is schematically configured.

  As shown in FIGS. 1 and 2, a plurality of filter media modules 2 provided in the biological reaction tank 1 are supported by a support 5. The support body 5 is schematically constituted by a pair of leg portions 5a that are spaced apart from each other and a rectangular plate portion 5b provided at an upper portion between the both leg portions 5a. The plate portion 5b is provided with a lifting member (not shown) so that each filter medium module 2 can be pulled up individually. The pulling member may be, for example, a groove or a hook that supports the filter medium module 2 so as to be movable in the vertical direction, but is not limited thereto. Further, a mechanically lifting mechanism (not shown) may be used for pulling up the filter medium module 2 and taking it out of the biological reaction tank 1 as shown in FIGS.

  In the first embodiment, four filter medium modules 2 (the most upstream filter medium module 2a, upstream side) along the flow direction from the upstream (inflow) side into which sewage flows into the downstream (outflow) side from which the mixed liquid flows out. A filter medium module 2 b, a downstream filter medium module 2 c and a most downstream filter medium module 2 d) are arranged, and these are supported by the support 5.

  Each filter medium module 2 is a rectangular frame, and a plurality of string-shaped filter media 6 are arranged in the vertical direction along the vertical direction, preferably parallel to each other and at a predetermined interval. As shown in FIG. 3, the string-like filter medium 6 is disposed at intervals along the longitudinal direction of the trunk yarn 6 a and the trunk yarn 6 a and extends in a direction away from the side surface of the trunk yarn 6 a. It comprises a plurality of branch yarns 6b. The string-like filter medium 6 under the water surface of the biological reaction tank 1 moves softly due to the flow in the biological reaction tank such as the flow of liquid (sewage and mixed liquid) and the flow of gas (aeration). It has a structure that flexibly swings up, down, left, and right using a portion connected to the trunk thread 6a as a fulcrum. On the surface of the string-like filter medium 6 configured in this manner, microorganisms that decompose organic substances and the like contained in the sewage flowing into the biological reaction tank 1 adhere and grow and accumulate to form a biofilm 6c. become.

The volume (bulk) occupied by the string-like filter medium 6 with respect to the volume of the biological reaction tank 1 is set in the range of 20% to 70% based on the treatment status (water volume and water quality), the size of the treatment facility, etc. 55% is preferable. In addition, as a method for fixing the string-like filter medium 6 to the filter medium module 2, a method of fixing both ends of the trunk thread 6a of the string-like filter medium 6 to the frame body of the filter medium module 2 by fixing means such as a hook can be cited. It is not limited to. Furthermore, the string-like filter medium 6 is desirably arranged in the vertical direction in the biological reaction tank 1, but may be arranged in the lateral direction depending on the situation.
In FIG. 3, the branch yarns 6b are alternately arranged on the left and right along the length direction of the trunk yarn 6a. However, the branch yarns 6b may be extended in both the left and right directions at the same position instead of the left and right alternates. . For example, one branch thread 6b is bound to the trunk thread 6a so as to extend in both the left and right directions. At that time, as shown in FIG. 16, an interval (0.5 to 10 cm) is provided along the length direction, and the plurality of branch yarns 6 b are bound by shifting the angle (15 to 60 degrees), The branch yarn 6b may be developed in a spiral shape (DNA shape). By setting it as such a shape, the string-like filter material 6 can be formed in three dimensions rather than planarly, and it is effective also in contact with sewage.

In the first embodiment, an air diffuser (a diffuser plate) 3a includes an uppermost air diffuser plate 3a and an upstream air diffuser installed below the four filter medium modules 2a, 2b, 2c, and 2d. 3b, a downstream air diffusion facility 3c and a most downstream air diffusion facility 3d, and a blower for supplying air to these, an air supply pipe, and a valve (none of which is shown) for adjusting the air amount, timing, etc. ing. Further, as the diffuser (aeration plate) 3a, for example, a fine cut is made in the upper part of a rubber tube, and this cut spreads by the expansion pressure of the air and becomes a jet outlet to discharge air or a porous type. Examples include, but are not limited to, ceramic plates. For example, an air diffuser (aeration tube) 3e shown in FIG. 6 having a large number of air holes on the surface and a jet-jet type air diffuser (not shown). ) May be used.
Note that the air diffuser (diffuser plate) 3 a only needs to be provided below the filter medium module 2, and may be provided, for example, at the bottom of the biological reaction tank 1. Moreover, in this Embodiment 1, although each diffuser plate (3a-3d) is each arrange | positioned in the position with respect to one filter medium module (2a-2d), it is not limited to this, The important point is If oxygen necessary for aerobic biological treatment can be supplied, the flow in the biological reaction tank 1 can be secured, and a diffused air that can peel the thickened biofilm 6c is obtained as necessary, the quantity and installation The location is not particularly limited.
Moreover, in order to obtain the said effect | action efficiently, as shown in FIG. 2, it arrange | positions so that a diffuser plate (3a-3d) can be separately diffused under the corresponding filter medium module (2a-2d). desirable. Further, in addition to the diffuser (diffuser plate) 3a, a diffuser for air cleaning for the filter medium module 2 may be provided separately, and foreign matter (entangled residue, etc.) of the string-like filter medium 6 of the filter medium module 2 ), Removal of the thickened biofilm 6c, elimination of blockage, and the like are preferable.

As shown in FIG. 1, the sedimentation separation tank 4 (solid-liquid separation facility) is roughly composed of a water tank 7 having a cone-shaped inclined bottom and a sludge scraper 8 disposed in the water tank 7. Yes. In the upper part of the water tank 7, a means (not shown) for receiving the mixed solution flowing out from the biological reaction tank 1 and a treated water discharge port 7b for discharging treated water are provided, and in the deepest part of the inclined bottom part, A sludge discharge port 7c for discharging the separated sludge is provided. The sludge scraping machine 8 rotates at the bottom of the water tank 7, and the sludge scraping plate 8a that scrapes the separated sludge accumulated on the bottom toward the sludge discharge port 7c and the rotation that generates the rotational driving force of the sludge scraping plate 8a. The motor 8b and the rotating shaft 8c which supports the sludge scraping plate 8a and transmits the rotational driving force of the rotary motor 8b are schematically configured. The separated sludge scraped is drawn out from the sludge discharge port 7c through the sludge extraction pump 23.
In addition, although the precipitation separation tank (circular sedimentation basin) was used as the solid-liquid separation equipment 4 in FIG. 1, it is not limited to this, For example, the rotary cylindrical solid-liquid separation tank 4 shown in FIG. A membrane separator immersed in the biological reaction tank 1 may be used, and of course, a rectangular sedimentation basin may be used. In short, any facility that can efficiently and reliably separate the mixed solution into treated water and separated sludge may be used.

  As shown in FIG. 1, the sludge return pipe 9 is a transfer pipe that returns the separated sludge extracted by the sludge extraction pump 23 from the sludge discharge port 7 c of the sedimentation separation tank 4 to the biological reaction tank 1 as return sludge. In addition, an on-off valve 24 is provided that opens and closes when the sludge return is stopped or the separated sludge is extracted as excess sludge. Similarly, an on-off valve 24 is provided in a sludge pipe for extracting the separated sludge as excess sludge and discharging it to the outside of the system. In the first embodiment, the return sludge is directly returned to the biological reaction tank 1, but not limited to this, in order to mix the return sludge and sewage in advance, for example, as shown in FIG. The sludge return pipe 9 may be configured to be connected to the sewage inflow pipe 25.

Next, sewage treatment will be described.
First, in the sewage treatment apparatus shown in FIG. 1, sewage is introduced into the biological reaction tank 1 and mixed with return sludge to perform aerobic biological treatment. When returning sludge cannot be secured sufficiently, such as during emergency recovery, it is desirable to put seed sludge procured from the outside into the biological reaction tank 1, and when it is difficult to obtain seed sludge, Inhabiting microorganisms may be propagated in the biological reaction tank 1 as seed sludge.
The sewage flowing into the biological reaction tank 1 is mixed with return sludge and seed sludge (that is, activated sludge), and aerobic biological treatment (mainly oxidative decomposition of organic matter) by aeration from the diffuser (aeration plate) 3a ) That is, the mixed liquid in which the sewage and the activated sludge are mixed flows in the biological reaction tank 1 under the flow of the extrusion flow in the tank or the upward flow due to the aeration, and comes into contact with the string-like filter medium 6. On the surface of the string-like filter medium 6, a biofilm 6c is formed and grows along with the aerobic biological treatment.
In the biofilm 6c, aerobic microorganisms proliferate with the oxidative decomposition of organic substances (BOD and CODMn) contained in the sewage, and SS adheres to the string-like filter medium 6 itself and the biofilm 6c (suspension of suspended substances). The biological film 6c (sludge) is enlarged over time, and a part of the biological film 6c is peeled off from the string-like filter material 6 (especially the swinging branch yarn 6b). .

Thus, on the surface of the string-like filter medium 6, a series of cycles consisting of the growth, enlargement and exfoliation of the biofilm 6c is always repeated, and the amount and biota of the activated sludge organisms responsible for the aerobic biological treatment of sewage. (Bacteria-protozoa-metazoans) are maintained, and the sewage is purified along with the activated sludge (living organisms) that floats.
The biofilm 6c is properly peeled, that is, SS (adsorbed suspended matter, entangled residue, etc.) adhering to the string-like filter medium 6 is removed, and the biofilm 6c thickened mainly by the branch thread 6b is formed. By peeling off and eliminating the blockage of the string-like filter medium, the surface area of the biofilm 6c, the swaying movement of the branch thread 6b, and the contact between the string-like filter medium 6 and the mixed liquid can be maintained well, and stable and efficient Aerobic biological treatment can be performed.

In short, the sewage flowing into the biological reaction tank 1 is first mixed with the activated sludge (returned sludge), and mainly the soluble organic matter and SS (suspended material) contained in the sewage are adsorbed on the activated sludge floc. Next, due to the flow in the tank, the organic matter and SS (suspended matter, residue, etc.) are adsorbed (attached) by contacting with the string-like filter medium 6, and the organic matter is oxidatively decomposed and purified under aerobic conditions due to aeration. It will be done.
Thus, in the biological reaction tank 1, since the string-like filter medium 6 is disposed in the presence of activated sludge (returned sludge), activated sludge organisms responsible for aerobic biological treatment can be sufficiently secured. Even if the amount of inflowing sewage or the amount of pollutant load increases, the sewage can be purified efficiently and reliably with an appropriate air diffuser, and treated water with good water quality can be discharged.
In addition, although the average residence time of the sewage in the biological reaction tank 1 is appropriately set according to the desired treatment water quality and treatment conditions, a range of approximately 0.5 to 24 hours is preferable, and a BOD volume load is preferably 0.1 to 5 A range of 0.0 kg BOD / m ³ · d is reasonable.

Next, cleaning of the filter medium module 2 (string filter medium 6) that plays an important role in aerobic biological treatment will be described.
In the biological reaction tank 1, the concentration of pollutants such as organic matter and SS is higher on the upstream (inflow) side where the sewage flows, and the amount of the biofilm 6 c attached to the string-like filter medium 6 than the downstream (outflow) side. There are many, and the growth speed becomes faster. For this reason, in the most upstream filter medium module 2a, the biofilm 6c is obviously thicker than the most downstream filter medium module 2d, and there is a high possibility that the string-shaped filter medium 6 is blocked. Therefore, as shown in FIG. 4, the uppermost filter medium module 2a that has a high possibility of blockage is sequentially pulled up to check the blockage (thickening) state. If blockage is confirmed, cleaning is performed promptly. Alternatively, the filter medium module 2 is returned to the support 5 and air cleaning (peeling operation) is performed by air diffusion (air discharge) using an air diffuser (aeration plate) 3a.
In addition, when the relationship between the property of the sewage flowing into the biological reaction tank 1 and the blockage state is clarified, the filter medium module 2 is periodically cleaned with air according to the property of the sewage. In addition, obstruction and associated processing malfunction can be avoided. In the air cleaning, for example, the amount of air discharged from the diffuser (diffuser plate) 3a is temporarily increased, and a large number of air bubbles collide with the thickened biofilm 6c, thereby removing the blockage.

Next, air cleaning of the filter medium module 2 (string-shaped filter medium 6) in the case where air is constantly diffused from the diffuser (diffuser plate) 3a will be described.
When the aeration device (aeration plate) 3a constantly diffuses, such as when the organic matter concentration of sewage is high, that is, when oxygen is always supplied to promote aerobic biological treatment, air bubbles are generated in the biological reaction tank 1. Ascending, an upward flow is formed in the tank. Then, the branch thread 6b of the string-like filter medium 6 continues to actively vibrate mainly due to the flow in the tank due to the rising of the air bubbles and the formation of the upward flow, and a part of the biofilm 6c is peeled off. Module 2 can be cleaned.
This aeration for aerobic biological treatment is also effective for peeling (cleaning) the thickened biofilm 6c, but depending on the location of the diffuser (aeration plate) 3a and the thickness of the biofilm 6c. It is difficult to properly clean all of the plurality of filter media modules 2.
Therefore, in the first embodiment, the diffuser plate (3a to 3d) is configured to be provided for each filter medium module (2a to 2d), and the amount of cleaning air appropriate for all the filter medium modules (2a to 2d) (for example, By setting the air volume to 1.2 to 2.5 times the normal amount) and an appropriate washing frequency (for example, washing the filter medium module 2a twice or more while washing the filter medium module 2d once) The filter medium module 2 can be reliably washed and maintained in a good state.

Next, the change of the installation place of the filter medium module 2 is demonstrated.
FIG. 5 shows a change in the installation location of the most upstream filter medium module 2a and the downstream filter medium module 2c.
The most upstream filter media module 2a, which has a high load of contamination (organic matter and suspended solids) and is likely to thicken the biofilm 6c, is taken out of the bioreactor 1, and after confirmation and cleaning of the string-like filter media 6 are performed, The downstream filter medium module 2c placed in a low load state and the installation location are changed. By appropriately performing such operations, the biological, physical, and chemical burdens applied to each string-like filter medium 6 and each filter medium module (2a to 2d) can be smoothed, and some string-like forms can be obtained. Extreme deterioration and breakage of the filter medium 6 and some filter medium modules 2 can be prevented.
5 is not limited to the installation location change example shown in FIG. 5, referring to the installation location change history of the filter medium module 2 and the clogging state of the string-like filter media 6, biological, physical, chemical It is desirable to change the installation location so that the load is as uniform as possible for each string-like filter medium 6.

In the biological reaction tank 1, aerobic biological treatment of sewage proceeds, and a mixed liquid of activated sludge including a part of the separated biofilm 6 c (peeled sludge) is transferred to the solid-liquid separation facility 4 (precipitation separation tank). In the sedimentation separation tank 4, the mixed liquid that has flowed in is solid-liquid separated into treated water and sedimented sludge by gravity sedimentation. The treated water is discharged (discharged) through the treated water discharge port 7b, the precipitated sludge is scraped by the sludge scraping plate 8a of the sludge scraper 8, and is drawn as a separated sludge from the sludge discharge port 7c by the sludge extraction pump 23. It is extracted and returned to the biological reaction tank 1 through the sludge return pipe 9. Some separated sludge is discharged out of the system as surplus sludge, and is treated and disposed of, such as dehydration and incineration.
Adjustment of the amount of return sludge and excess sludge, return (drawing) time, and the like is appropriately performed by operating the sludge drawing pump 23 and the on-off valve 24. When the pollution load is very low, the separated sludge is not returned to the biological reaction tank 1 as described above. In that case, the biological reaction tank 1 will serve as a so-called catalytic oxidation tank, and the separated sludge (generated amount: small amount) mainly composed of exfoliated sludge will be discharged out of the system for disposal. . The amount of sludge returned is preferably set in a range of 0% to 100% with respect to the amount of inflow of sewage depending on various situations.

  As described above, according to the first embodiment, in the biological reaction tank 1, the inflowing sewage is treated with activated sludge, and the string-like shape is swayed by the flow of air in the biological reaction tank 1 or inflow of sewage. The biofilm 6c that adheres to and proliferates on the filter medium 6, especially the branch thread 6b, is efficiently contacted and purified. When the pollution load is high, the amount of returned sludge is increased (high MLSS) and the air is sufficiently diffused to ensure that the sewage can be aerobically treated. When the pollution load becomes low, the sludge is returned. By reducing the amount (low MLSS) and suppressing the amount of aeration, energy consumption can be suppressed and sewage can be treated aerobically efficiently. In addition, since it is possible to perform aerobic biological treatment of such appropriate sewage, it is possible to quickly obtain seed sludge at the time of emergency response, that is, to increase activated sludge, and also to a sewage treatment facility in the vicinity of recovery The activated sludge propagated to can be supplied as seed sludge and can contribute to the establishment of this facility.

Even if the pollution load is high and the string-like filter medium 6 may be frequently clogged, the filter medium module 2 can be pulled up to easily check and clean the clogged state, and thereby the surface area of the biofilm 6c. The swinging movement of the branch thread 6b and the contact between the string-like filter medium 6 and the mixed liquid are maintained well, and sufficient oxygen can be always supplied to the biofilm 6c, so that the biological treatment capacity of the biological reaction tank 1 can be maintained well. Moreover, since the filter medium module 2 can be pulled up and the degree of adhesion of the biofilm 6c for each filter medium module 2 can be confirmed, air cleaning conditions (amount of cleaning air, frequency of cleaning) can be easily set for each filter medium module 2.
In the first embodiment, four filter media modules 2a to 2d are arranged in a row in the biological reaction tank 1, but the tank shape and scale of the biological reaction tank 1, the scale of the sewage treatment facility, etc. Accordingly, the number and arrangement of the filter media modules may be changed. Moreover, although it is desirable that the shape of the filter medium module 2 is unified in the sewage treatment apparatus, a filter medium module having a different shape according to the shape of the biological reaction tank 1 or the required processing capacity (for example, a floating cylindrical filter medium). Or a fixed fibrous filter medium) may be mixed.

  In the biofilm 6c adhering to the string-like filter medium 6 of the filter medium module 2 and the activated sludge in the biological reaction tank 1, there are bacteria having a relatively low metabolic (growth) rate for removing nitrogen and phosphorus from the sewage. Since these bacteria easily flow out from the biological reaction tank 1 to the solid-liquid separation facility 4 together with the mixed solution, the performance of removing nitrogen and phosphorus from the sewage is deteriorated. Therefore, in order to maintain the removal performance of nitrogen and phosphorus, it is desirable to introduce the floating carrier carrying the bacteria into the biological reaction tank 1. As the floating carrier, for example, a sponge-like cube or a porous filter medium can be used. As a floating carrier material, the biofilm 6c is unnecessarily peeled by contact with the string-like filter medium 6. A soft one is preferable to a hard one so as not to streak.

  In the first embodiment, as shown in FIG. 3, the string-like filter medium 6 composed of the trunk thread 6a and the branch thread 6b is suitable. However, the present invention is not limited to this, and the string-like filter medium is not limited to this. The biofilm 6c is formed, the enlargement (growth) proceeds, a part of the biofilm 6c is peeled off, and a new growth is repeated. Any configuration, structure, and material may be used. For example, the portion corresponding to the branch yarn 6b may be a ring-like or spiral long yarn.

Embodiment 2. FIG.
FIG. 6 is a partial cross-sectional view showing the overall configuration of the sewage treatment apparatus according to Embodiment 2 of the present invention, and FIG. 8 (a) shows a rotary screen type screen removal machine 20 that is the screen residue removal equipment 14 of FIG. It is a fragmentary sectional view shown. The same constituent elements as those in FIGS.
The sewage treatment apparatus according to the second embodiment has a point that a sewage inflow pipe 25 is provided with a rotary screen type scum remover 20 as a scum removal equipment 14 and a diffusing pipe 3e as a diffuser. Different from the configuration in the first embodiment.

  As shown in FIG. 8 (a), the rotary screen type debris removal machine 20 is opened by a sewage inflow conduit 25, and a rotary screen 20a formed of a wedge wire or a bar, and a screw for transferring the captured debris. Consists of a conveyor 20b and a drive unit 20c for driving them, and traps the residue contained in the sewage flowing through the sewage inflow conduit 25 toward the biological reaction tank 1, and is being conveyed by the screw conveyor 20b. By compaction action on the residue, the residue is dehydrated, dehydrated and discharged.

  Further, the air diffusion pipe 3e is a pipe member having corrosion resistance such as a vinyl chloride pipe, and a plurality of air diffusion holes are provided, and flows downward (longitudinal) at the lower part (usually near the bottom part) of the biological reaction tank 1. It extends along the direction. As long as the installation place is below the filter medium module 2, it may be directly under the filter medium module 2 or any other place, and the number of installation may be one or more. In short, there is no particular limitation as long as the inside of the biological reaction tank 1 can be reliably diffused, the flow in the tank can be generated, and the thickened biological film 6c can be peeled off.

  In the sewage treatment apparatus according to the second embodiment configured as described above, part or all of the separated sludge discharged from the sedimentation separation tank 4 is returned to the biological reaction tank 1 through the sludge return pipe 9, thereby In the reaction tank 1, MLSS can be normally maintained at 1000 to 5000 mg / L. Then, the sewage from which the residue has been removed is introduced into the biological reaction tank 1 by the rotary screen type residue remover 20, and the activated sludge and the string-like filter medium 6 are subjected to aerobic conditions due to the diffusion from the diffusion tube 3 e. By the biofilm 6c that has grown and adhered, sewage can be efficiently and reliably aerobically treated.

As described above, according to the second embodiment, since the rotary screen type debris removing machine 20 is provided, it is possible to sufficiently remove debris contained in the sewage, and only the string-like filter medium 2 is thereby obtained. It is possible to suppress the entanglement of fibrous foreign matters such as residue on the filter medium module 6 and to prevent the biofilm 6c from being excessively enlarged, ensuring a sufficient surface area of the biofilm 6c, so The synergistic effect enables efficient and good aerobic biological treatment, and is effective in reducing excess sludge including exfoliated sludge.
If the returned sludge contains a large amount of fibrous foreign matter (sediment etc.), the sludge return pipe 9 is extended to the upstream side of the sewage transfer pipe 25 by the rotary screen type residue remover 20 and returned. You may remove the fibrous foreign material (sediment etc.) contained in sludge.

Embodiment 3 FIG.
FIG. 7 is a partial cross-sectional view showing the overall configuration of the sewage treatment apparatus according to Embodiment 3 of the present invention, and FIG. 8B shows a screen-type debris removal machine 21 that is the debris removal equipment 14 of FIG. It is a fragmentary sectional view. The same constituent elements as those in FIGS.
The sewage treatment apparatus according to the third embodiment has a sewage inflow conduit 25 provided with a screen-type scum remover 21 as a slag removal facility 14, a branch pipe 10 branched from the sewage inflow conduit 25, and a branch pipe. The configuration in the second embodiment in that it has a branch pipe 11 extending from 10, a branch pipe 12 extending from the branch pipe 11, and a sewage inlet 13 that is provided in each pipe and allows sewage to flow into the biological reaction tank 1. Different. In addition, the diffuser (diffuser plate) 3a is employ | adopted similarly to Embodiment 1. FIG.

  As shown in FIG. 8 (b), the screen type debris remover 21 is disposed in the sewage inflow conduit 25, and a screen 21a formed of a wedge wire or a bar, and the debris captured by the screen 21a. A scraping member (rake) 21d for scraping, a plurality of scraping members 21d, a chain belt 21b for moving the scraping member 21d along the screen 21a, and a drive unit 21c for driving the chain belt 21b The sewage contained in the sewage flowing through the sewage inflow conduit 25 toward the biological reaction tank 1 is trapped and transported and discharged while scraping the trapped residue.

  Further, as shown in FIG. 7, the branch pipe 10 branches from the sewage inflow conduit 25, and a sewage inlet 13 is provided between the uppermost filter medium module 2 a and the upstream filter medium module 2 b of the biological reaction tank 1. The branch pipe 11 extends from the branch pipe 10 and flows in between the upstream filter medium module 2b and the downstream filter medium module 2c of the biological reaction tank 1 through the sewage inlet 13. The branch pipe 12 extends from the branch pipe 11 and allows sewage to flow between the downstream filter medium module 2c and the most downstream filter medium module 2d of the biological reaction tank 1 through the sewage inlet 13. .

  In the sewage treatment apparatus according to the third embodiment configured as described above, the sewage from which the scum has been removed flows into the biological reaction tank 1 by the screen-type scum remover 21, but the branch pipe 10, the branch pipe 11 and The branch pipe 12 allows sewage to flow at a plurality of locations from the upstream side to the downstream side of the bioreactor 1 so that the sewage flowing into the bioreactor 1 is immediately mixed with activated sludge at each inflow site. Moreover, it becomes possible to contact with the biofilm 6c, and aerobic biological treatment can be performed quickly and efficiently.

  In Embodiment 3, the branch pipe 11 is extended from the branch pipe 10, and the branch pipe 12 is extended from the branch pipe 11. However, the present invention is not limited to this, and both the branch pipe 11 and the branch pipe 12 are directly connected. It may be branched from the sewage inflow conduit 25, or a plurality of branch pipes may be provided directly in the scum removal equipment 14 without passing through the sewage inflow conduit 25. It is sufficient if the sewage from which the residue is removed can be introduced.

As described above, according to the third embodiment, since the screen type screen residue removing device 21 is provided, the screen residue contained in the sewage can be sufficiently removed. It is possible to suppress the entanglement of fibrous foreign matters such as residue on the sludge material module 6 and to prevent excessive enlargement of the biofilm 6c, ensuring a sufficient surface area of the biofilm 6c and synergizing with activated sludge. The effect enables efficient and favorable aerobic biological treatment, and is effective in reducing excess sludge including exfoliated sludge.
Embodiment 2 FIG. Similarly, since the sewage inlet 13 is provided in plural, the sewage from which the residue is removed can be caused to flow into a plurality of locations of the biological reaction tank 1, and the aerobic biological treatment can be promptly performed at each inflow location. Since the pollutant load in the biological reaction tank 1 can be dispersed, the adhesion growth (thickening) of the biofilm 6c of the string-like filter medium 6 can be smoothed, that is, the bias can be eliminated. It is also effective for improving the efficiency of cleaning work.
Furthermore, when the pollutant load is reduced by reducing or diluting the inflow of sewage, the biological reaction tank 1 stops returning sludge and switches to low load operation while suppressing the amount of air, but the situation of low pollutant load continues. Then, for example, the biofilm 6c of the string-like filter medium 6 of the most downstream filter medium module 2d may have an organic matter load, that is, the supply of the substrate may be interrupted, and a dismantling phenomenon occurs, making it difficult to maintain the biofilm 6c. Also in such a case, the second embodiment. Similarly, in the sewage treatment apparatus according to Embodiment 3, the sewage from which the residue has been removed is allowed to flow into a plurality of locations in the biological reaction tank 1 to supply the substrate throughout the biological reaction tank 1. Thus, the biofilm 6c of the string-like filter medium 6 of the filter medium module 2 (especially the downstream 2c and 2d) can be maintained.

Embodiment 4 FIG.
FIGS. 9A, 9B, and 9C are partial cross-sectional views (one cross-sectional view through which sewage flows down) showing the configuration of the biological reaction tank 1 of the sewage treatment apparatus according to Embodiment 4 of the present invention. . The same constituent elements as those in FIGS.
In the fourth embodiment, different patterns are illustrated and described for the arrangement of the filter medium module 2 in the biological reaction tank 1 of the sewage treatment apparatus and the diffuser 3a provided below the filter medium module 2.
That is, in FIG. 9A, the filter medium module 2 is disposed along one side wall of the biological reaction tank 1, and a diffuser (aeration plate) 3a is provided near the bottom of the other side wall. In FIG.9 (b), the filter medium module 2 is arrange | positioned along both the side walls of the biological reaction tank 1, and the diffuser (diffuser plate) 3a is provided in the bottom vicinity of the biological reaction tank 1 center part. In FIG. 9 (c), the filter medium module 2 is arranged except for the vicinity of both side walls of the biological reaction tank 1, and a diffuser (diffuser pipe) 3 e is provided near the bottom immediately below the filter medium module 2.

  In Fig.9 (a), by having comprised as mentioned above, the air supplied through the air pipe 26a from the air blower 26 of the air diffusion equipment 3 is diffused from the air diffuser (air diffuser board) 3a, and air bubbles Ascending, an upward flow is generated in the vicinity of the side wall where the diffuser (aeration plate) 3a is provided in the biological reaction tank 1, and the reverse flow is reversed near the side wall where the filter medium module 2 is disposed. It becomes a flow. Thereby, a swirling flow in the vertical direction is formed in the biological reaction tank 1, the mixed liquid in the biological reaction tank 1 flows, the string-like filter medium 6 of the filter medium module 2 is shaken, and activated sludge and string-like filter medium 6 are further moved. Oxygen can be supplied to the biofilm 6c. In addition, since the air diffuser (diffuser plate) 3a is not provided directly under the filter medium module 2 and the rising air bubbles hardly collide with the string-shaped filter medium 6, the biofilm 6c is peeled gently. Become.

  In FIG.9 (b), by having comprised as mentioned above, the air supplied through the air pipe 26a from the air blower 26 of the air diffusion equipment 3 is diffused from the air diffuser (air diffuser board) 3a, and air bubbles Ascending, an upward flow is generated near the center of the biological reaction tank 1 where the diffuser (aeration plate) 3a is provided, and it is reversed near both side walls where the filter medium module 2 is disposed. Down flow. As a result, a swirling flow in the vertical direction is formed in the biological reaction tank 1, and the same actions and effects as in FIG. 9A can be obtained.

In FIG.9 (c), by having comprised as mentioned above, the air supplied through the air pipe 26a from the air blower 26 of the air diffusion equipment 3 is diffused from two diffusers (air diffuser pipes) 3e, and air Due to the rising of the bubbles, an upward flow is generated toward the filtration module 2 disposed in the biological reaction tank 1, and the flow is reversed and flows downward near both side walls where the filter medium module 2 is not disposed. As a result, a swirling flow in the vertical direction is formed in the biological reaction tank 1, the mixed liquid in the biological reaction tank 1 flows, and the string-like filter medium 6 of the filter medium module 2 is actively shaken, and further activated sludge and strings Oxygen can be supplied to the biofilm 6 c of the filter medium 6.
The diffuser (aeration tube) 3e is provided immediately below the filter medium module 2, and the rising air bubbles always collide with the string-shaped filter medium 6, so that the biofilm 6c is peeled off, and the biofilm 6c peeling and new growth can be promoted.

As described above, according to the fourth embodiment, the filter medium module 2 and the air diffuser (3a and 3e) can be appropriately disposed in the biological reaction tank 1, and the quality and amount of sewage flowing in Good and stable aerobic biological treatment can be performed by selecting an appropriate configuration in consideration of factors such as seasonal variation and the size of the sewage treatment facility.
In addition, when there is much inflow of sewage, the flow in the bioreaction tank 1 is sufficiently obtained, and peeling of the biofilm 6c is always promoted, the configuration of FIG. 9 (a) or FIG. 9 (b). In the case where the inflow of sewage is small or the pollution load is high, and the thickening of the biofilm 6c is likely to proceed, the configuration of FIG. 9C is preferable.

Embodiment 5. FIG.
FIG. 10 is a partial cross-sectional view showing the overall configuration of the sewage treatment apparatus according to Embodiment 5 of the present invention, and FIG. 11 is a diagram showing the configuration of the rotating cylindrical solid-liquid separation tank 4 which is the solid-liquid separation facility of FIG. 11 (a) is a front view showing the external configuration of the rotating cylinder, FIG. 11 (b) is an AA arrow view of FIG. 11 (a), and FIG. 11 (c) is the rotating cylinder. It is sectional drawing which shows the whole structure of the type solid-liquid separation tank 4, and attaches | subjects the same code | symbol to the same component as FIG. 1 thru | or FIG. 9, and abbreviate | omits duplication description.
In the sewage treatment apparatus according to the fifth embodiment, an upflow-type filter medium tank 22 is provided as a residue removal facility 14 in the sewage inflow conduit 25, and the sludge return pipe 9 is connected to the sewage inflow conduit 25. It differs from the structure by Embodiment 1 thru | or 4 by the point which provided the rotation cylinder type solid-liquid separation tank 4 as a solid-liquid separation equipment.

As shown in FIG. 10, a filter bed 22 a filled with a filter medium is disposed in the upward flow type filter medium tank 22 as the residue removing equipment 14, and is introduced from the lower part of the upward flow type filter medium tank 22. By passing the sewage in an upward flow through the filter bed 22a, it is possible to reliably capture and remove residue and suspended matter such as fibrous foreign matter contained in the sewage, and the sewage from which the residue has been removed. Flows out from the upper part of the upward flow type filter medium tank 22 and is sent to the biological reaction tank 1. Thereby, in the biological reaction tank 1, not only the string-like filter medium 6, but also the entanglement of fibrous foreign matters such as residue on the filter medium module 2 can be suppressed, and excessive enlargement of the biofilm 6c can be prevented. Sufficient surface area of the biofilm 6c can be secured, and the synergistic effect of the biofilm 6c and activated sludge enables efficient and good aerobic biological treatment, which is also effective in reducing excess sludge including exfoliated sludge. is there.
The filter medium filled in the filter bed 22a can be a string-shaped filter medium 6. However, a floating cylindrical filter medium, sand gravel, a ceramic member, a fibrous filter medium or the like that can securely capture and retain the residue is used. They are preferably used and may be mixed. In addition, the filter medium is washed (excluded trapping residue) by temporarily stopping the inflow of sewage into the upward flow type filter medium tank 22, lowering the tank water level, and supplying the wash water from above. (Flash cleaning).

  On the other hand, as shown in FIG. 10, the sludge return pipe 9 is connected to the sewage inflow pipe 25 so that the separated sludge discharged from the solid-liquid separation facility 4 can be returned to the biological reaction tank 1. When performing the aerobic biological treatment, the sewage from which the residue has been removed and the return sludge can be mixed in the sewage inflow pipe 9 in advance and can be introduced into the biological reaction tank 1. As a result, the sewage and the return sludge are mixed in advance and immediately after flowing into the biological reaction tank 1, the aerobic biological treatment can be performed quickly and efficiently, and the sewage and the returned sludge flow into the biological reaction tank 1 together. Therefore, a sufficient flow (extrusion flow) can be formed in the tank, the swinging movement of the string-like filter medium can be promoted, and sludge accumulation on the tank bottom can be prevented.

  As shown in FIGS. 11 (a), 11 (b) and 11 (c), the rotating cylinder 15 of the rotating cylinder type solid-liquid separation tank 4 is arranged below the water surface of the water tank 7 or so that the upper end comes out above the water surface. The sludge scraper 8 is supported by the rotary shaft 8c and can be rotated by the rotary motor 8b. As shown in FIGS. 11 (a) and 11 (b), the rotary cylinder 15 has a plurality of separation blades 16 disposed along the circumference, and a gap 17 is formed between the separation blades 16. ing. The separation blade 16 is an elongated plate-like member whose transverse cross-sectional shape is bent in the shape of “<” or “he” in the rotary cylinder 15.

  The mixed liquid introduced into the rotating cylinder 15 rotating from the mixed liquid introducing port 7a rotates gently along with the rotation of the rotating cylinder 15, and the centripetal force acts on the sludge floc 18 contained in the mixed liquid. While being moved toward (rotating shaft 8c direction), it settles to the bottom of the water tank 7 due to gravity. At that time, the fine sludge flocs 18 and the like try to flow out of the rotating cylinder 15 on the flow of the treated water from the gap 17 formed with a width of about 1 to 100 mm, but the separating blade 16 that is rotating is rotating. Since it collides with the bent shape portion and is returned to the inner side of the rotary cylinder 15, outflow can be prevented. On the other hand, the treated water (clear water from which the sludge flocs 18 and the like are separated) passes through the gap 17 and flows out to the outside of the rotary cylinder 15 and is discharged.

Thus, the sludge floc 18 of the mixed liquid introduced into the rotating cylinder 15 is prevented from flowing out of the rotating rotating cylinder 15, and the sludge floc 18 is placed in the sludge zone formed below the rotating cylinder 15. In addition, the solid-liquid separation proceeds efficiently, and the sludge flocs 18 and the like can be separated more quickly and reliably than ordinary gravity precipitation, and sludge precipitated by more efficient solid-liquid separation. The concentration of can also be increased.
The rotating cylinder 15 is supported by the rotating shaft 8c of the sludge scraping machine 8, and may be rotated at the same speed as the sludge scraping plate 8a by the rotating motor 8b. May be rotated separately.

  In the fifth embodiment, the separation blade 16 has a cross-sectional shape of "" or "", but the sludge floc 18 and the like in the rotary cylinder 15 flows out of the rotary cylinder 15. If it is a difficult structure, it may be plate-shaped, bowl-shaped, deformed in the shape of “ku” or “he”, gently curved, or sharply bent Good. Further, the separation blades 16 may all have the same shape and size, or may be the same shape and size every other one, or may be all random. The intervals 17 do not have to be equal intervals, and may be set to be the same interval every other one or even every two intervals. Furthermore, the shape of the separation blade 16 may be appropriately selected from a strip shape, a trapezoidal shape, a square shape, a semicircular shape, and the like in consideration of the size of the rotary cylinder 15 and the water load.

  As described above, according to the fifth embodiment, by adopting the upward flow type filter medium tank 22 as the screen residue removal equipment 14, the screen residue can be more reliably removed than the screen-type screen screen removal device with a coarse screen. It can be removed, and sewage and return sludge can be mixed in advance, and good aerobic biological treatment can be performed. In addition, by adopting the rotating cylindrical solid-liquid separation tank 4 as the solid-liquid separation equipment, it is possible to separate the sludge floc 18 and the like quickly and reliably compared to the gravity precipitation, thereby enabling efficient solid-liquid separation. In addition, it is possible to increase the concentration of the separated sludge that is discharged by increasing the concentration of the precipitated sludge by efficient solid-liquid separation, and it is possible to reduce the volume of sludge to be treated and disposed of (surplus sludge), and surplus sludge It is possible to reduce labor, energy, cost, etc. related to processing, transportation and disposal.

Example 1.
Example 1 is an example of aerobic biological treatment of sewage performed using the sewage treatment apparatus shown in FIG. FIG. 12 shows the change over time in the removal rate of BOD (shown by a black diamond), the CODMn removal rate (shown by a black square), and the SS removal rate (shown by a black triangle) with respect to the removal of main pollution indicators of sewage. The removal rate of each pollution index is shown as an average value for each week during the implementation period.
The operating condition is a period with a small pollution load, the BOD concentration of the sewage is 55 to 65 mg / L, the BOD volume load is 0.25 to 0.30 kg / m ³ · d, and the sludge return rate is 10 to 10%. At 20%, the bioreactor suspended sludge concentration (MLSS) was 800-1000 mg / L.
During the implementation period, the BOD removal rate is maintained at approximately 75% or higher, the CODMn removal rate is maintained at approximately 62% or higher, and the SS removal rate is maintained at approximately 80% or higher. It is shown that processing is taking place.
Also from the removal rate of these pollution indexes (BOD, CODMn, SS), the sewage treatment apparatus in Embodiment 1 of the present invention is a biofilm 6c that adheres and grows on the activated sludge and the string-like filter medium 6 in the biological reaction tank 1. It can be seen that the MLSS can be kept low with a low sludge return rate and energy saving operation with low air volume, and efficient and stable aerobic biological treatment performance can be maintained. .

Example 2
This Example 2 is an example of the aerobic biological treatment of sewage performed using the sewage treatment apparatus shown in FIG. FIG. 13 shows changes over time in the removal rate of BOD (shown by black diamond), CODMn removal rate (shown by black square), and SS removal rate (shown by black triangle) regarding the removal of main pollution indicators of sewage. The removal rate of each pollution index is shown as an average value for each week during the implementation period.
The operating condition is a period with a large pollution load, the BOD concentration of the sewage is 150 to 190 mg / L, the BOD volumetric load is 0.90 to 1.10 kg / m ³ · d, and the sludge return rate 85 to At 110%, the MLSS of the bioreactor was 2000-2700 mg / L.
During the implementation period, the BOD removal rate is maintained at 80% or higher, the CODMn removal rate is maintained at 70% or higher, and the SS removal rate is maintained at 88% or higher. It is shown that processing is taking place.
From the removal rate of these pollution indicators (BOD, CODMn, SS), the sewage treatment apparatus in Embodiment 2 of the present invention is a biofilm 6c that adheres and grows on the activated sludge and the string-like filter medium 6 in the biological reaction tank 1. It can be seen that a reliable and stable aerobic biological treatment performance can be maintained by an operation in which MLSS is maintained high at a high sludge return rate in response to a high pollutant load.

Example 3
This Example 3 is an example of the aerobic biological treatment of sewage performed using the sewage treatment apparatus shown in FIG. 6 and changing the sludge return rate. FIG. 14 is a graph showing the time-dependent change of MLSS in the biological reaction tank 1, where the very low pollution load (sludge return rate of 5%) is indicated by a black diamond and the high pollution load ( The sludge return rate is 90%). Each MLSS shows an average value for each week during the implementation period.
During the implementation period, the growth (proliferation) and separation of the biofilm 6c due to the swaying movement of the branch thread 6b of the string-like filter medium 6 and the rising air bubbles, the respective filter medium modules 2 being pulled up, and the string-like filter medium 6 being blocked by residue etc. Since the situation and the amount of biofilm adhered were appropriately controlled, MLSS was approximately constant at 250 to 300 mg / L at low load and 2300 to 2500 mg / L at high load. Since the MLSS was kept constant, oxygen supply to the biofilm 6c adhered and grown with the activated sludge and the string-like filter medium 6 and the state of treatment (adsorption / oxidation / decomposition) of pollutants were maintained. You can see that

Example 4
This Example 4 is an example of the aerobic biological treatment of sewage performed using the sewage treatment apparatus shown in FIG. FIG. 15 is a graph showing the change over time in the separation sludge concentration when the rotating cylindrical solid-liquid separation tank 4 is installed as the solid-liquid separation equipment shown in FIG. 10, and the sludge return rate is 10% and the MLSS is 1000 mg / L. The low load operation time is shown by a black diamond, and the sludge return rate is 100% and the high load operation of MLSS 2700 mg / L is shown by a black square. The separated sludge concentration is an average value for each week during the implementation period. During the implementation period, the pollutant load on the bioreactor 1 was generally constant (average BOD volumetric load: about 1.0 kg / m ³ · d). In order to confirm the high separation performance of the rotary cylindrical solid-liquid separation tank 4 and the increase in the concentration of the separated sludge, the precipitation separation tank 4 shown in FIG. 1 is used from the first week to the fourth week of the implementation period. Then, from the fifth week to the eighth week of the implementation period, the aerobic biological treatment was performed using the rotating cylindrical solid-liquid separation tank 4.

  As can be seen from FIG. 15, the separated sludge concentration from the first week to the fourth week during low load operation was 10,000 to 11000 mg / L, but the separated sludge concentration from the fifth week to the eighth week was 12000 to 13000 mg / L. L, and the separated sludge concentration from the first week to the fourth week at high load operation was around 12000 mg / L, but the separated sludge concentration from the fifth week to the eighth week was 13,000 to 14000 mg / L, By installing the rotary cylindrical solid-liquid separation tank 4, the solid-liquid separation performance was improved and the separation sludge concentration was stably increased, thereby reducing the amount of excess sludge discharged.

1 biological reactor,
2 filter media module,
2a Uppermost filter medium module, 2b Upstream filter medium module,
2c downstream filter medium module, 2d most downstream filter medium module,
3 Aeration equipment,
3a Air diffuser (diffuser plate, uppermost stream diffuser plate), 3b upstream diffuser plate,
3c downstream diffuser, 3d most downstream diffuser, 3e diffuser (diffuser tube),
4 Solid-liquid separation equipment (precipitation separation tank, rotary cylindrical solid-liquid separation tank),
5 support,
5a leg part, 5b board part,
6 String filter media,
6a trunk thread, 6b branch thread, 6c biofilm,
7 Aquarium,
7a mixed liquid inlet, 7b treated water outlet, 7c sludge outlet,
8 Sludge scraper
8a Sludge scraping plate, 8b Rotating motor, 8c Rotating shaft,
9 Sludge return pipe,
10 first branch pipe, 11 second branch pipe, 12 third branch pipe,
13 Sewage inlet, 14 Sediment removal equipment,
15 rotating cylinders, 16 separating blades, 17 gaps,
18 Sludge frock,
20 Rotating screen type screen residue remover (screen residue removal equipment),
20a rotating screen, 20b screw conveyor, 20c driving machine,
21 Screen type screen residue remover (screen residue removal equipment),
21a screen, 21b chain belt, 21c driver,
21d scraping member,
22 Upflow type filter media tank (sediment removal equipment), 22a Filter bed,
23 sludge extraction pump, 24 on-off valve, 25 sewage inflow conduit,
26 Blower, 26a Air pipe

Claims (5)

A bioreactor that introduces sewage to treat aerobic organisms;
A solid-liquid separation facility for solid-liquid separation of the mixed liquid in the biological reaction tank into treated water and separated sludge;
A sludge return pipe for returning the separated sludge to the biological reaction tank;
One or two or more filter medium modules provided with a string-like filter medium having stem yarns and branch yarns are provided in the biological reaction tank,
An air diffuser provided below the filter medium module ;
The rectangular plate portion includes a pair of leg portions spaced apart from each other and a rectangular plate portion provided at an upper portion between the both leg portions, and means for holding the filter medium module so as to be individually liftable is provided. A sewage treatment apparatus comprising a support . The sewage treatment apparatus according to claim 1, further comprising a scum removal facility for removing scum contained in the sewage. The sewage treatment apparatus according to claim 1, wherein the biological reaction tank includes a plurality of sewage inlets. The solid-liquid separation equipment is
A tank,
A plurality of separation blades are arranged with a gap, and a rotating cylinder into which the mixed solution flows,
A drive for rotating the rotating cylinder;
The sewage treatment apparatus according to any one of claims 1 to 3, wherein the sewage treatment apparatus is a rotating cylindrical solid-liquid separation tank provided with a sludge scraper that scrapes the separated separated sludge. One or more filter media modules in which a plurality of string-like filter media having trunk yarns and branch yarns are arranged are provided in a biological reaction tank,
Introducing sewage into the biological reactor,
Perform aerobic biological treatment by aerating from below the filter media module,
Solid-liquid separation of the liquid mixture flowing out from the biological reaction tank into treated water and separated sludge,
Returning a part or all of the separated sludge to the biological reaction tank ,
When the pollution load becomes high, increase the amount of sludge returned to the biological reaction tank of the separated sludge,
The sewage treatment method for a sewage treatment apparatus according to any one of claims 1 to 4 , wherein when the pollutant load becomes low, the amount of sludge returned to the biological reaction tank of the separated sludge is reduced .

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