Microbial Reactor

Abstract

Provided is a microorganism reaction tank which can efficiently prevent activated sludge from accumulating inside the tank. This microorganism reaction tank 1 comprises: an outer tank 2; a cylindrical inner tank 3 disposed inside the outer tank and having an opening above and below; a circulation rate control device 4 for controlling the circulation rate of treated water inside the tank; a cylindrical control plate 5 for causing the sludge to settle; a treated water quality measurement device 6; a raw water supply port 10 provided in a circulation path of the treated water circulating in the outer tank 2 and the inner tank 3, and a treated water discharge port 11 provided on an upper part of the outer tank 2; and a settling / solidifying prevention device 12 for preventing settling / solidifying of the settled sludge. The settling / solidifying prevention device 12 includes a first scraper 13 extending along an inclined surface 3h of a cylindrical upper part 3c, and a second scraper 14 extending along an inclined inner wall of the outer tank lower part. The first scraper 13 and the second scraper 14 are connected, and integrally rotate inside the outer tank 2 in the circumferential direction.

Description

[Technical field]

[0001] The present invention relates to a microbial reaction tank, and more particularly to a device for preventing accumulation of sludge in a microbial reaction tank. [Background technology]

[0002] Wastewater containing high concentrations of pollutants such as nitrogen, phosphorus, and organic matter, which increase biochemical oxygen demand (BOD) and suspended solids (SS), is a cause of environmental pollution, such as river pollution and red tide. The so-called modified Barnard process, which is one of the aerobic-anaerobic circulation processes, has been known as a method for treating wastewater containing such high concentrations of pollutants. In this method, in order to reuse the alkali released during the denitrification reaction in the nitrification reaction, the denitrification process in the activated sludge treatment process is divided into two stages, a first denitrification tank and a second denitrification tank, which are located before and after the first nitrification tank, and a second nitrification tank is further installed after the second denitrification tank, and the mixed liquid discharged from the first and second nitrification tanks is circulated to the first denitrification tank.

[0003] However, wastewater treatment using this method has the following problems. (1) High concentrations of ammonia nitrogen are themselves bactericidal, and therefore often inhibit the activity of activated sludge in the activated sludge treatment process, resulting in insufficient activated sludge treatment. (2) In the so-called modified Barnard process, the hydrogen ion concentration (hereinafter referred to as pH) decreases as the nitrification reaction progresses in the nitrification tank, but since the nitrification reaction depends on pH, a decrease in pH slows down the nitrification reaction. As a result, activated sludge treatment becomes insufficient, and phosphorus removal becomes insufficient. (3) If activated sludge treatment is insufficient and the denitrification reaction is slow, the concentrations of residual ammonia, nitrate ions, and nitrite ions will increase, resulting in an increase in the BOD, which depends on these nitrogen compounds, and insufficient wastewater treatment. (4) Wastewater containing high concentrations of pollutants requires high-concentration activated sludge, which inevitably leads to a high concentration of activated sludge suspended solids (hereafter referred to as MLSS). This makes it difficult to supply oxygen, as well as to agitate the activated sludge and separate the solids and liquids in the settling tank. (5) When denitrification and denitrification are performed on wastewater containing a high nitrogen content, even if the organic pollutant concentration is low, problems such as a decrease in pH and floating of sludge due to denitrification occur.

[0004] In order to address the above-mentioned problems, the present inventors have proposed a microbial reaction tank capable of efficiently carrying out activated sludge treatment of wastewater containing pollutants such as high concentrations of nitrogen and phosphorus components and organic substances, and a wastewater treatment method using the same (Patent Document 1). This microbial reaction tank is equipped with an inner tank having a nitrification reaction section and a denitrification reaction section above and below, which are connected by turbine blades.

[0005] However, in the above-mentioned conventional microbial reaction tank, the anaerobic tank formed in the lower part of the inner tank where the denitrification reaction takes place and the aerobic tank formed in the upper part of the inner tank where the nitrification reaction takes place were connected only by turbine blades, so when the capacity of the reaction tank was large, there was a problem that the mixing in each tank was insufficient and the anaerobic or aerobic reaction did not proceed sufficiently. In addition, there were problems such as high construction costs for the reaction tank and high costs for fixing the inner tank inside the outer tank.

[0006] In order to address the above problems, the present inventors have improved the above-mentioned conventional microbial reaction tanks, and have proposed a microbial reaction tank and a wastewater treatment method using the same that can maintain a high in-tank circulation rate and perform anaerobic and aerobic microbial treatment continuously even if the reaction tank capacity is large, and can reduce construction costs (Patent Document 2). Furthermore, this microbial reaction tank is equipped with a settling and immobilization prevention device to prevent settling and immobilization of settled sludge. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 11-128987 [Patent Document 2] International Publication No. 2013 / 132610 Summary of the Invention [Problem to be solved by the invention]

[0008] In the above-mentioned Patent Document 2, in order to prevent the sludge from settling and becoming fixed in the lower part of the outer tank where the sludge is likely to settle, a settling and fixation prevention device such as a vibration device, a vibration plate, a scraper, and an agitation flow generator is provided in the lower part of the outer tank. However, depending on the internal shape of the microbial reaction tank, sludge may be likely to settle in places other than the lower part of the outer tank. Therefore, there is room for further improvement in the device for preventing the sludge from settling and becoming fixed.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a microbial reaction tank that can continuously perform anaerobic and aerobic microbial treatment while maintaining a high circulation rate within the tank, even when the capacity of the reaction tank is large, and can efficiently prevent activated sludge from accumulating within the tank. [Means for solving the problem]

[0010] The microbial reaction tank of the present invention is a microbial reaction tank comprising an outer tank, a cylindrical inner tank disposed inside the outer tank and having openings at the top and bottom, a circulation rate control device disposed in the upper part of the cylindrical inner tank for controlling the circulation rate of the water to be treated within the tank, a cylindrical control plate disposed with its open lower surface close to the inclined surface on the upper outer periphery of the cylindrical inner tank for settling sludge, treated water quality measuring devices disposed on the outside and inside of the cylindrical inner tank, a raw water supply port disposed in the circulation path for the water to be treated circulating within the outer tank and the inner tank, and a treated water discharge port disposed in the upper part of the outer tank. This microbial reactor has the following features: (1) The cylindrical inner tank is divided into an upper cylindrical portion and a lower cylindrical portion by a partition wall having a communicating hole in the center. (2) The cylindrical upper portion has a truncated cone-shaped top portion with an open top and bottom, the outer periphery of the top portion being the inclined surface, and a plurality of air inlets are provided around the communication holes and on the peripheral edge of the partition wall within the cylindrical upper portion; (3) The lower part of the cylinder is an anaerobic microbial treatment tank having an opening on the bottom. (4) Agitation devices are provided for agitating the inside of the aerobic microbial treatment tank and the anaerobic microbial treatment tank, respectively. (5) A settling and fixation prevention device for preventing the settling and fixation of the settled sludge is provided in the outer tank, and the settling and fixation prevention device has a first scraper extending along the inclined surface of the upper part of the cylinder and a second scraper extending along the inclined inner wall of the lower part of the outer tank, the first scraper and the second scraper being connected to each other and rotating circumferentially within the outer tank together. (6) The circulation rate control device includes a means for detecting at least one measured value selected from the pH, oxidation-reduction potential (hereinafter referred to as ORP) and amount of dissolved oxygen (hereinafter referred to as DO) of the water to be treated measured by the water quality measuring device, and a means for controlling the circulation rate within the tank of the water to be treated to 3 to 20 in accordance with the measured value detected by this means, and this circulation rate control device controls at least one quantity selected from the opening and closing of the liquid level control valve, the rotation or up and down movement of the liquid level control plate, and the amount of air blown in from the air blowing port. Here, the circulation rate within the tank of the water to be treated refers to the quantity defined by the following formula. Circulation rate of treated water in the tank = Amount of treated water discharged from the top of the inner tank (m 3 / day) / Raw water supply amount (m 3 / day) (7) The raw water supplied from the raw water supply inlet is circulated within the tank together with the activated sludge through the inside of the cylindrical inner tank, the outer surface of the cylindrical inner tank, and within the activated sludge that has settled at the bottom of the outer tank, thereby continuously carrying out anaerobic microbial treatment and aerobic microbial treatment.

[0011] The above microbial reactor further has the following features: (8) In the cylindrical upper portion of the cylindrical inner tank, the inclination angle of the inclined surface in a height direction cross section passing through the center of the truncated cone shape is 40 degrees to 60 degrees. (9) The first scraper and the second scraper each have a plurality of plate members for scraping off the settled sludge, and in each scraper, the plurality of plate members are arranged parallel to each other and fixed at an angle with respect to a plane perpendicular to the direction of rotation. (10) The first scraper and the second scraper each have the multiple plate members, a fixed member for fixing the multiple plate members, and a roller attached to the fixed member, and the first scraper moves along the inclined surface of the upper part of the cylinder by rolling of the roller, and the second scraper moves along the inclined inner surface of the lower part of the outer tank by rolling of the roller. (11) A driving means capable of rotating in a circumferential direction is arranged around the entire inner surface of the outer tank, and the settling and fixation prevention device is connected to the driving means and rotates in a circumferential direction within the outer tank as the driving means rotates. Effect of the Invention

[0012] In the microbial reaction tank of the present invention, the cylindrical inner tank arranged inside is divided into an upper cylindrical tank and a lower cylindrical tank by a partition wall having a communicating hole in the center, so that the anaerobic and aerobic microbial treatment of raw water containing high concentrations of pollutants can be continuously performed while maintaining a high circulation rate in the tank. Furthermore, the settling and immobilization prevention device has a first scraper and a second scraper, and these scrapers are integrally installed so as to be rotatable in the circumferential direction, so that the sludge can be prevented from settling and immobilizing on the inclined surface of the cylindrical inner tank and the lower part of the outer tank in the microbial reaction tank. As a result, the anaerobic and aerobic microbial treatment of raw water containing high concentrations of pollutants can be continuously performed while maintaining a high circulation rate in the tank, the cylindrical inner tank can be made into a simple shape, and the microbial reaction tank can be easily installed even when the capacity of the reaction tank is large. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view of one embodiment of a microbial reactor of the present invention. [Diagram 2] FIG. 2 is an enlarged view of the sedimentation and fixation prevention device of FIG. 1. [Diagram 3] FIG. 4 is a plan view showing the arrangement position of the settling and fixation prevention device. [Figure 4] FIG. 2 is a cross-sectional view of another embodiment of a microbial reactor of the present invention. [Diagram 5] FIG. 2 is a plan view of a first scraper and a second scraper. [Figure 6] FIG. 2 is a diagram showing the circulation paths of the water to be treated and activated sludge in a microbial reaction tank. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An embodiment of the microbial reaction tank of the present invention will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view of the microbial reaction tank. The microbial reaction tank 1 is composed of an outer tank 2, a cylindrical inner tank 3 placed inside the outer tank 2, a circulation rate control device 4 provided on the upper part of the cylindrical inner tank 3, a cylindrical control plate 5 provided on the outer periphery of the cylindrical inner tank 3, and a treated water quality measuring device 6. A sludge discharge port 27 can be provided. The present invention does not limit the tank volume of the microbial treatment equipment and can be applied to both small and large scale equipment. However, the effect is most pronounced when the microbial reaction tank 1 is 20 m 3 or more, preferably 30 to 6000 m 3 This is the case when applied to a microbial reactor with an internal volume of 6000 m. 3 When the water level exceeds 20m, it becomes difficult to create a circulating flow. 3 In the case of a small-scale system that does not satisfy the above requirement, the advantage of circulating sludge up and down within the microbial reaction tank 1 is diminished.

[0015] The outer tank 2 has a true cylindrical appearance consisting of a base 2a serving as the bottom surface, a cylindrical side surface 2b, and a top surface 2c. A rotating shaft 7 for mounting an agitator blade is provided at the center of the cylinder. This rotating shaft 7 is rotatably fixed by a stand 2d provided at the center of the base 2a and a bearing 2e provided at the center of the top surface 2c. The rotating shaft 7 is rotated by a driving device 2f. The top surface 2c rotatably fixes the rotating shaft 7 and holds the cylindrical inner tank 3 with a support. In FIG. 1, a geared motor 21 is provided on the top surface 2c. As described later, the geared motor 21 drives a drive chain by rotating a drive wheel 23 below the water surface through a shaft 22. A raw water supply port 10 is provided at the bottom of the outer tank 2, at the lower part of the cylindrical inner tank 3. The raw water supply port 10 is composed of a plurality of discharge ports 10b or slits provided in an annular raw water supply section 10a arranged below the lower opening 3f of the cylindrical inner tank 3. By arranging the raw water supply port 10 in this manner, the anaerobic sludge is sufficiently agitated. Note that the raw water supply port 10 can be provided in a place other than the lower part of the cylindrical inner tank 3 as long as it is in the circulation path of the water to be treated. In addition, a purified treated water discharge port 11 is provided at the top of the outer tank 2. A lower inner surface 2g of the outer tank 2 is an inclined surface whose diameter decreases toward the bottom. The inclination angle of the lower inner surface 2g in the height direction cross section of the microbial reaction tank 1 is, for example, 40 degrees to 60 degrees, preferably 45 degrees.

[0016] A cylindrical inner tank 3 is placed inside the outer tank 2. As shown in Fig. 1, the cylindrical inner tank 3 has a substantially circular cross section (see Fig. 3), and is divided into an upper cylindrical portion 3c and a lower cylindrical portion 3d by a partition wall 3a. A communication hole 3b is provided in the center of the partition wall 3a, which connects the upper cylindrical portion 3c with the lower cylindrical portion 3d. Due to the presence of this partition wall 3a, even if the volume of the microbial reaction tank becomes large, the cylindrical upper part 3c and the cylindrical lower part 3d are sufficiently separated, and activated sludge treatment can be carried out in each tank. Aerobic microbial treatment reaction can be carried out sufficiently in the cylindrical upper part 3c, and anaerobic microbial treatment reaction can be carried out sufficiently in the cylindrical lower part 3d. If the area of ​​the partition wall 3a becomes large, it is reinforced with a support member 3g or the like. The diameter of the communication hole 3b is large enough to allow the activated sludge that has been anaerobically treated to move from the lower cylinder 3d to the upper cylinder 3c, which is the aerobic microbial treatment section. The diameter of this communication hole 3b is adjusted depending on the volume of the microbial reaction tank, the properties and amount of raw water to be treated, etc.

[0017] The upper cylinder portion 3c has a top portion of a truncated cone shape with the top and bottom surfaces open. That is, the tip of the cylindrical portion is shaped so that the diameter of the tip of the cylindrical portion is reduced at a predetermined angle in the height direction. The outer surface of the top portion is an inclined surface 3h. The inclination angle of the inclined surface 3h in the height direction cross section passing through the center of the truncated cone is, for example, 40 degrees to 60 degrees, preferably 45 degrees. By setting the inclination angle of the inclined surface 3h in the range of 40 degrees to 60 degrees, the sludge contained in the treated water discharged from the upper part of the aerobic tank flows down the outer surface of the truncated cone, which makes the sludge more likely to coagulate due to the so-called boycott effect, and allows the sludge to be rapidly forced to settle. In addition, the coagulation of the sludge makes it easier to separate the sludge from the purified treated water. The inclination angle of the inclined surface 3h is preferably equal to the inclination angle of the lower inner surface 2g of the outer tank 2.

[0018] The cylindrical upper portion 3c is an aerobic microbial treatment tank with air blowing inlets 8 and 8a provided therein. The air blowing inlet 8 is provided around the central axis 7 and the communication hole 3b, and can be fixed to the partition wall 3a by a support column (not shown) or the like. The air outlet of the air blowing inlet 8 is preferably arranged facing downwards, since it can contribute to stirring the water to be treated and sludge in the aerobic tank. The air blowing port 8a can be either a plurality of air holes 8c provided in the air blowing section 8b arranged in a circular shape in a plan view on the peripheral edge of the partition inside the cylindrical upper part 3c, or a slit formed on the top or side surface of the air blowing section 8b. The amount of air blown in through the air blowing ports 8 and 8a and the control amount of the circulation rate control device described later can be used to vary the circulation amount of the water to be treated within the range of 3 to 20 without using a circulation pump. This makes it easy to set aerobic microbial treatment under appropriate nitrification conditions and anaerobic microbial treatment under appropriate denitrification conditions. Furthermore, solid-liquid separation of sludge is extremely efficient due to the principle of forced settling on the outer periphery of the aerobic microbial treatment tank having the above-mentioned inclination angle, so that aerobic and anaerobic microbial treatment reactions can be efficiently carried out in the same vertical tank. In addition, an alkali supply port or an acid supply port (not shown) may be provided in the aerobic tank.

[0019] The lower cylinder portion 3d is an anaerobic microbial treatment tank having a volume 1 / 10 to 1 times the volume of the upper cylinder portion. If the volume is within this range, the aerobic microbial treatment reaction and the anaerobic microbial treatment reaction of raw water containing high concentration nitrogen-containing pollutants can be efficiently carried out. Note that the anaerobic microbial treatment tank can be provided with a denitrifying bacteria nutrient supply port (not shown). In addition, when the raw water contains a small amount of hydrogen donor and nitrogen from nitrates is denitrified by supplying a hydrogen donor such as methanol or acetic acid, it is preferable to make the volume of the anaerobic microbial treatment tank larger than that of the aerobic microbial treatment tank. The shape of the lower cylinder 3d is an inverted truncated cone with an opening 3f that is larger in area than the opening 3e of the upper cylinder 3c. In other words, the tip of the cylinder tapers downward at a specified angle. By increasing the area of ​​the opening 3f, it is possible to easily agitate the sludge in the anaerobic microbial treatment tank. When the lower cylinder portion 3d is shaped like an inverted truncated cone, it is preferable that the lower inner surface 2g of the outer tank 2 has the same angle as the above-mentioned predetermined angle, since this prevents the sludge from settling and becoming fixed.

[0020] As described above, the microbial reaction tank 1 allows for rapid forced settling of sludge. Therefore, sludge is likely to accumulate not only at the bottom of the outer tank 2, but also on the lower periphery of the inclined surface 3h of the upper cylindrical portion 3c. Therefore, in the present invention, a settling and immobilization prevention device (sludge scraping device) that prevents the settling and immobilization of sludge is provided at these locations. Specifically, as shown in FIG. 1, the settling and immobilization prevention device 12 has a first scraper 13 that extends along the inclined surface 3h of the upper cylindrical portion 3c, and a second scraper 14 that extends along the lower inner surface 2g of the outer tank 2. These are connected by a connecting member 15, and the integrated scraper (settlement and immobilization prevention device 12) is provided so as to be rotatable in the circumferential direction. By rotating the integrated scraper, the sludge accumulated on the lower periphery of the inclined surface 3h is scraped off by the first scraper 13, and the sludge accumulated on the lower inner surface 2g of the outer tank 2 is scraped off by the second scraper 14. This effectively prevents activated sludge from accumulating in the tank.

[0021] The settling and immobilization prevention device 12 will be described in detail with reference to Fig. 2. As shown in Fig. 2, the first scraper 13 is disposed approximately parallel to the inclined surface 3h at the top of the cylinder, and includes a scraper body 13a, a fixing member 13b for fixing the scraper body 13a, and a roller 13c provided on the fixing member 13b and capable of rolling on the inclined surface 3h. A plurality of rollers 13c (two rollers) are provided at intervals in the inclined surface direction of the inclined surface 3h. In the first scraper 13, a gap is formed between the scraper body 13a and the inclined surface 3h. The second scraper 14 is disposed approximately parallel to the lower inner surface 2g of the outer tub 2, and includes a scraper body 14a, a fixing member 14b for fixing the scraper body 14a, and a roller 14c provided on the fixing member 14b and capable of rolling on the lower inner surface 2g. A plurality of rollers 14c (three in number) are provided at intervals in the direction of the inclined surface of the lower inner surface 2g. In the second scraper 14, a gap is formed between the scraper body 14a and the lower inner surface 2g.

[0022] As shown in FIG. 2, the first scraper 13 and the second scraper 14 are connected and integrated by a plurality of connecting members 15. A support member 15a, which is one of the connecting members 15, is disposed in the horizontal direction and directly supported by a support roller 17c. The connecting members 15 connect, for example, the connecting members to each other, the support member 15a and the first scraper 13, and the support member 15a and the second scraper 14. Also, in FIG. 2, the fixing member 13b of the first scraper 13 extends to the second scraper 14 and is connected to the fixing member 14b of the second scraper 14.

[0023] The integrated scraper is supported by a support base 17a protruding from the inner wall of the cylindrical side surface 2b. The support base 17a is provided with a guide portion 17b and a support roller 17c, and the support roller 17c is configured to receive the load of the integrated scraper in the vertical downward direction. For example, an H-shaped steel or an I-shaped steel can be used for the guide portion 17b. A guide roller 16 that can rotate in the horizontal direction is provided at the outer diameter side end of the support member 15a. When the settling and fixation prevention device 12 rotates in the circumferential direction, the guide roller 16 rotates while abutting against the guide portion 17b, thereby reducing the positional deviation of the scraper and achieving smooth movement.

[0024] In the present invention, the sedimentation and immobilization prevention device 12 can rotate in the circumferential direction in the outer tank 2. The microbial reaction apparatus is provided with a driving means for rotating the sedimentation and immobilization prevention device 12. In FIG. 2, a driving chain 20 is provided as the driving means. The driving chain 20 is an endless chain arranged around the entire circumference of the inner wall of the cylindrical side surface 2b of the outer tank 2. The driving chain 20 rotates in the circumferential direction by the rotation of a driving wheel (see FIG. 1) and a driven wheel 19. The driven wheel 19 is installed at the lower part of a support base 18 protruding from the inner wall of the cylindrical side surface 2b. As shown in FIG. 2, one end of the support member 15a is connected to one point in the circumferential direction of the driving chain 20, so that the first scraper 13 and the second scraper 14 rotate in synchronization with the rotation of the driving chain 20. In FIG. 2, the weight of the sedimentation and immobilization prevention device 12 is supported by the roller 13c, the roller 14c, and the support roller 17c. Since the drive chain 20 is not subjected to a vertical load due to the weight of the sinking and fixation prevention device 12, it is less likely to break down and stable rotation can be ensured.

[0025] FIG. 3 is a plan view of the microbial reaction tank 1 of FIG. 1 as seen from above. As shown in FIG. 3, the outer tank 2, the cylindrical inner tank 3, and the cylindrical control plate 5 are arranged concentrically. The support base 18 is arranged around the entire circumference of the cylindrical side surface 2b of the outer tank 2, and below the support base 18, a plurality of (9) driven wheels 19 are provided at a predetermined interval in the circumferential direction. In addition, below the support base 18, a drive wheel 23 is provided at one location in the circumferential direction between the driven wheels 19. The drive wheel 23 is connected to a shaft 22 that rotates by driving a geared motor, and can be driven to rotate. The drive chain 20 is stretched around the drive wheel 23 and the plurality of driven wheels 19, and is arranged around the entire circumference of the inner wall of the outer tank 2. The settling and fixation prevention device 12 is located at one location in the circumferential direction of the cylindrical inner tank 3, and as the drive wheel 23 rotates in the direction of the arrow, the drive chain 20 and the settling and fixation prevention device 12 rotate in one direction (X direction) within the outer tank 2. The rotation axis of the settling and fixation prevention device 12 and the rotation center of the rotation axis 7 are aligned. In Fig. 3, the drive wheel 23 is provided at one location in the circumferential direction of the tank, but it may be provided at multiple locations. Also, multiple settling and fixation prevention devices may be attached to the drive chain. In this case, the multiple settling and fixation prevention devices may have different shapes or the same shape.

[0026] 3, the first scraper 13 and the second scraper 14 in the settling and immobilization prevention device 12 are at the same circumferential position (in the same phase), but the first scraper 13 and the second scraper 14 may be configured to be at different circumferential positions (out of phase). For example, by configuring the first scraper 13 to be located downstream of the second scraper 14 in the rotation direction, the sludge scraped off by the first scraper 13 can be further scraped off by the subsequent second scraper 14.

[0027] In addition, since the drive chain 20 is installed below the liquid surface, it is preferable that it is made of a material with high water resistance. For example, a metal material such as stainless steel, or a resin material such as polyacetal resin or high density polyethylene resin is used. When a resin material is used, the chain needs to be adjusted for stretching or replaced through regular maintenance, but stable drive is possible. Note that, although a drive chain is used as the drive means in FIG. 2, this is not limiting. For example, a drive belt may be used instead of the drive chain. By providing a driving means such as a drive chain or a drive belt, and by providing a power unit such as a drive roller at only one or several points in the circumferential direction inside the tank, it is possible to rotate the settling and fixation prevention device along the inner wall of the tank via the above-mentioned driving means. Therefore, there is no need for a driving unit to be provided around the entire circumferential direction at the top or bottom of the device, which reduces manufacturing costs and management and maintenance costs.

[0028] In the embodiment of Figs. 1 to 3, a drive chain is used as a means for rotating the sedimentation and fixation prevention device, but the present invention is not limited to this as long as the sedimentation and fixation prevention device can rotate in the circumferential direction within the outer tank.

[0029] Another embodiment of the microbial reaction tank of the present invention is shown in Fig. 4. The microbial reaction tank 1 in Fig. 4 is similar to the microbial reaction tank 1 in Fig. 1 except for the configuration in which the sedimentation and immobilization prevention device is rotated. As shown in FIG. 4, a circular rail 24 is provided around the entire circumference of the upper part of the cylindrical side surface 2b of the outer tank 2 at a position above the liquid surface. A self-propelled driving cart 25 is installed on the rail 24. For example, a trolley may be installed under the rail 24 to supply power from the trolley. The arm of the driving cart 25 and the settling and fixation prevention device 12 are connected by a connecting member 26. Specifically, the connecting member 26 is connected to the support member 15a of the connecting member 15 that connects the first scraper 13 and the second scraper 14. In this configuration, the driving cart 25 runs on the rail 24, so that the settling and fixation prevention device 12 can rotate in the circumferential direction inside the outer tank. The connecting member 26 can be a rigid body such as a metal rod or a flexible wire. In the microbial reaction tank 1 in Fig. 4, the sedimentation and immobilization prevention device is rotated from above the liquid surface, so that maintenance of the driving cart 25 and the like is easy. In addition, by making the driving cart 25 self-propelled, the power unit does not become too large, and manufacturing costs and management and maintenance costs can be reduced.

[0030] Next, the first scraper 13 and the second scraper 14 will be further described with reference to Fig. 5. Fig. 5(a) is a plan view of the first scraper, and Fig. 5(b) is a plan view of the second scraper. In Fig. 5, the rollers provided on each scraper are located on the back side of the fixed member.

[0031] As shown in FIG. 5(a), the first scraper 13 has a plurality of plate members 13d and 13e as the scraper body 13a. The plate members 13d and 13e are arranged parallel to each other and are fixed at an angle with respect to a plane f perpendicular to the rotation direction (X direction). Specifically, the outer ends of the plate members 13d and 13f are inclined at an angle α toward the upstream side in the rotation direction. When arranged along the inclined surface 3h (see FIG. 2), the outer ends of the plate members 13d and 13e are located on the lower side of the inclined surface 3h. Therefore, the sludge is guided as shown by the black arrow and is easily dropped to the lower side of the inclined surface 3h. In addition, the plate members 13d and 13e are arranged so that the inner end of the plate member 13d and the outer end of the plate member 13e overlap in the rotation direction. The fixing member 13b is configured in a lattice shape, and the plate members 13d and 13e are fixed at multiple points.

[0032] As shown in FIG. 5(b), the second scraper 14 has a plurality of plate members 14d, 14e as the scraper body 14a. The plate members 14d and 14e are arranged parallel to each other and fixed at an angle with respect to a plane f perpendicular to the rotation direction (X direction). Specifically, the inner ends of the plate members 14d, 14e are inclined at an angle β toward the upstream side in the rotation direction. When arranged along the lower inner surface 2g (see FIG. 2), the inner ends of the plate members 14d, 14e are located on the inclined lower side of the lower inner surface 2g. Therefore, the sludge is guided as shown by the black arrow and is easily dropped to the inclined lower side of the lower inner surface 2g. In addition, the plate members 14d, 14e are arranged so that the inner end of the plate member 14d and the outer end of the plate member 14e overlap in the rotation direction. The fixing member 14b is configured in a lattice shape, and the plate members 14d, 14e are fixed at multiple points.

[0033] 5, the angles α and β are each in the range of 0 degrees or more and less than 90 degrees, preferably 20 degrees to 70 degrees, and more preferably 30 degrees to 60 degrees. Furthermore, the magnitude relationship between the angles α and β is not particularly limited, but it is preferable that they are equal to each other. In Fig. 5, the scraper body has a plurality of plate members, and these plate members are inclined with respect to a plane perpendicular to the rotation direction, but this is not limited thereto, and for example, the scraper body may be made of a single plate member, and this plate member may be configured parallel to the plane perpendicular to the rotation direction. Also, the scraper body may be made of a single plate member, and this plate member may be configured to be inclined with respect to the plane perpendicular to the rotation direction.

[0034] The materials of the connecting member and the plate member (scraper body) constituting the first scraper and the second scraper are not particularly limited as long as they have sufficient mechanical strength and corrosion resistance during rotation. For example, they are formed of metal materials such as stainless steel or reinforced resin materials such as engineering plastics. When made of resin, they can be made lighter and the load on the driving means during rotation can be reduced. In addition, by making them from resin, they have excellent sliding properties, and they may be in contact with the inclined surface of the inner tank or the like without leaving a gap between them. In addition, the connecting member and the plate member may be made of different materials, and the connecting member may be made of metal and the plate member made of resin may be fixed to it.

[0035] Returning to Figure 1, the cylindrical inner tank 3 is provided with an agitation device to ensure sufficient treatment reaction between the water to be treated and activated sludge in the aerobic microbial treatment tank which is the cylindrical upper portion 3c and in the anaerobic microbial treatment tank which is the cylindrical lower portion 3d. The agitation device is preferably an agitation impeller 7a or 7b fixed to a rotating shaft 7 attached to the center of the cylindrical inner tank 3. The agitation impeller 7a is preferably a turbine impeller that is provided inside the upper cylindrical portion 3c and can sufficiently carry out the aerobic microbial treatment reaction. In addition to the turbine impeller, any shape that can mix air and water and has a relatively low rotation speed that does not significantly reduce the aeration performance depending on the amount of air blown in can be used. The stirring blade 7b is provided inside the lower cylinder portion 3d, and any stirring blade that can sufficiently carry out the anaerobic microbial treatment reaction can be used, but turbine blades and propeller blades are preferred.

[0036] The partition wall 3a provided in the cylindrical inner tank 3 is supported by a number of support columns 9 fixed to and erected on the base 2a which forms the bottom surface of the outer tank 2. The buffer effect of the support columns 9 disrupts the agitation flow in the anaerobic microbial treatment tank, enabling efficient agitation within the tank. The cylindrical inner tank 3 is supported within the outer tank by the support columns 9 and by a support tool that bridges the upper part of the outer tank 2.

[0037] A circulation rate control device 4 is provided on the upper part of the cylindrical inner tank 3 to control the circulation rate of the water to be treated in the tank. The circulation rate control device 4 is composed of a liquid level control valve and / or liquid level control plates 4a and 4b provided on a concentric cylinder (see FIG. 3). The liquid level control plates 4a and 4b have vertical slits on both or one of them. The circulation rate of the water to be treated in the tank is controlled, specifically, by opening and closing the liquid level control plates 4a and 4b by mutual rotation, which have vertical slits on both sides, or by mutual up and down movement of the liquid level control plates 4a and 4b, which have vertical slits on one side and no slits on the other side. The water level of the water to be treated is lowest when the liquid level control valve is fully open, when the slits of the liquid level control plate are fully open, or when the liquid level control plate without slits is at the lowest position of up and down movement. The water level is indicated by A.

[0038] The circulation rate in the tank can also be controlled by the amount of air blown in through the air blowing inlet 8 and / or 8a. Increasing the amount of air blown in increases the circulation rate. Opening and closing the liquid level control valve and adjusting the amount of air can also be combined.

[0039] As the anaerobic and aerobic microbial treatment tanks become larger, the aeration air alone may not be enough to maintain the sludge circulation flow rate, and excessive air blowing may cause problems. In preparation for such a case, an air inlet shown in 8a in FIG. 1 is required. This air inlet 8a, which has poor aeration efficiency, has the advantage of making it much easier to adjust the amount of air blown and the ORP. For example, the air inlet 8a is provided in the aerobic part, which is the upper surface of the partition wall 3a, with an air blowing section 8b, which is circular in plan view and communicates with an external blower or the like, centered on the stirring blade 7a, and this air blowing section 8b is provided with holes or slits. This not only simply increases the amount of air, but also exerts the baffle effect of the stirring blade 7a, resulting in a synergistic effect of efficient stirring.

[0040] By adjusting the opening and closing of the liquid level control valve and / or the amount of air blown in, the circulation rate of the water to be treated within the tank can be varied without using a pump. As described below, the water to be treated is circulated from the aerobic microbial treatment tank 3c through a cylindrical control plate 5 arranged outside the tank to the anaerobic microbial treatment tank 3d, and then from the anaerobic microbial treatment tank 3d to the aerobic microbial treatment tank 3c, thereby performing denitrification, dephosphorization, etc. Therefore, by controlling the circulation rate of the water to be treated within the tank based on a predetermined control program in response to the detected value, optimal denitrification, dephosphorization, etc. can be performed.

[0041] A cylindrical control plate 5 is disposed on the outer periphery of the upper part of the cylindrical inner tank 3. The cylindrical control plate 5 is a tube with an open top and bottom, and the bottom surface 5a of the cylindrical control plate 5 is disposed close to the inclined surface 3h of the cylindrical inner tank 3. A sludge settling part is formed in the inclined surface portion disposed close to the cylindrical inner tank 3, where the sludge is thickened and the treated water is separated. Furthermore, by disposing the bottom surface 5a close to the cylindrical inner tank 3, the sludge can be rapidly and forcibly settled. It is preferable that the distance of the bottom surface 5a from the inclined surface 3h of the cylindrical inner tank 3 can be adjusted according to the type and amount of sludge. Moreover, the shape of the cylindrical control plate 5 can be a right cylinder with the opening surfaces of the top and bottom surfaces having the same area, or an inverted truncated cone shape with the opening area of ​​the top surface being larger than the opening area of ​​the bottom surface. In the microbial reaction tank, treated water quality measuring devices 6 are provided inside and outside the cylindrical inner tank 3. The treated water quality measuring devices 6 are devices that measure the pH, ORP, and DO of the treated water.

[0042] The circulation rate of the water to be treated in the microbial reaction tank of the present invention is 3 to 20, preferably 5 to 20. If the circulation rate of the water to be treated in the tank is less than 3, the aerobic microbial treatment reaction is more likely to occur, and if it exceeds 20, the balance between the aerobic microbial treatment reaction and the anaerobic microbial treatment reaction is lost, and denitrification and dephosphorization of the raw water cannot be performed. That is, by setting the circulation rate of the water to be treated in the tank within this range, the ORP of the water to be treated measured by the water quality measuring device can be maintained at -10 mV or less, preferably -50 mV or less in the anaerobic microbial treatment reaction tank, and +10 mV or more, preferably +100 mV or more in the aerobic microbial treatment reaction tank. As a result, the aerobic microbial treatment reaction and the anaerobic microbial treatment reaction are sufficiently performed, and denitrification and dephosphorization are continuously performed. Under such conditions, the pH in the aerobic microbial treatment reaction tank is in the range of 4.5 to 8.5, preferably 5.5 to 7.5.

[0043] The wastewater treatment method using the microbial reaction tank 1 is a wastewater treatment method in which raw water is treated by a treatment process including an activated sludge treatment process, which includes a sludge circulation process for forming a circulating flow of activated sludge, and a raw water addition process for adding raw water to the circulating flow of activated sludge. The above-mentioned circulating flow of activated sludge is a flow that circulates from the anaerobic microbial treatment tank through the aerobic microbial treatment tank, where treated water is separated and sludge is concentrated in the sludge settling section, and the concentrated sludge is sent to the anaerobic microbial treatment tank. The above-mentioned activated sludge treatment process is a sludge circulation process and a raw water addition process that are treated using the above-mentioned microbial reaction tank.

[0044] The wastewater treatment method using the microbial reaction tank 1 has the following excellent features compared to conventional wastewater treatment methods. In conventional wastewater treatment methods, raw water and returned sludge are mixed in a fixed ratio and flow into an aeration tank. The raw water is pushed out and flows away, coming into contact with only the same activated sludge bacteria until the returned sludge comes into contact with the sludge and the raw water are separated from each other in the next process, the settling tank, and the activated sludge and raw water that were initially mixed are discharged. The wastewater treatment method using the microbial reaction tank 1 is a method in which a circulating flow of activated sludge that circulates up and down is formed and raw water is added to this circulating flow. This is an energy-saving wastewater treatment method because it does not require a circulating pump to create a circulating flow of activated sludge, but instead uses the upward flow of the aeration air used in the microbial treatment to form a circulating flow of sludge. Furthermore, this treatment method allows for efficient aeration in the aerobic microbial treatment tank. The raw water may be added anywhere within the circulation flow path, but is preferably added to an aerobic microbial treatment tank. More preferably, an anaerobic microbial treatment tank is suitable. In the case of treatment using a circulation flow in the wastewater treatment method of the present invention, even if the raw water has a BOD of at least 800 mg / L or more and a total nitrogen content (hereinafter referred to as TN) of 40 mg / L or more, the BOD of the treated water is usually extremely low, 20 mg / L or less, and generally, operation can be performed with a BOD of 10 mg / L or less as the water quality of the discharged water. If raw water is added to the sludge settling section in the circulating flow path formed on the outer periphery of the cylindrical inner tank, which is the aerobic microbial treatment tank, the contact between the sludge and the raw water may be insufficient, resulting in insufficient adsorption of pollutants. In such cases, some of the pollutants in the untreated raw water may be mixed into the treated water, causing deterioration of the treated water. However, when water quality regulations are loose, for example, when the BOD is 300 mg / L or less or 600 mg / L or less and the primary treatment equipment is used for sewage discharge, raw water may be added to the sludge settling section in the circulating flow path.

[0045] Hereinafter, a method for treating raw water containing high-concentration nitrogen-containing pollutants using the microbial reaction tank 1 will be specifically described with reference to Fig. 6. Fig. 6 is a diagram showing the circulation paths of the water to be treated and activated sludge in the microbial reaction tank 1 of Fig. 1. In Fig. 6, the shaded areas are areas with high concentrations of activated sludge, and the arrows indicate the circulation directions of the water to be treated and the activated sludge. Raw water as the water to be treated containing pollutants from which solids have been separated using a wedge wire screen or the like is continuously supplied from a raw water supply port 10 provided at the bottom of the microbial reaction tank 1. It is preferable to measure the BOD and SS of the raw water to be supplied in advance. For example, the raw water may contain a BOD of 800 mg / L or more, a chemical oxygen demand (hereinafter referred to as COD) of 300 mg / L or more, and a TN of 40 mg / L or more. It is also suitable for treating raw water containing a normal hexane extractable oil concentration (hereinafter referred to as n-Hex) in the range of 50 mg / L or more.

[0046] The microbial reaction tank 1 contains 5,000 to 12,000 mg / L of activated sludge converted to solids, and the raw water first comes into contact with the activated sludge in an anaerobic state in the lower cylinder 3d, where a denitrification reaction takes place. The raw water to be treated, supplied from the raw water supply port 10, and the circulating activated sludge are circulated within the lower cylinder 3d by the rotation of the agitator or the ejection of air from the air diffuser, and undergo an anaerobic microbial treatment reaction. Next, the raw water and activated sludge move through the communication holes 3b to the upper cylinder 3c into which air is being blown, and while in contact with the activated sludge in the upper cylinder 3c under aerobic conditions, they circulate inside the upper cylinder 3c by the rotation of the stirring blades or the blowing of air from the air blowing port, and the nitrification reaction, which is an aerobic microbial treatment reaction, proceeds. As the nitrification reaction proceeds, the pH of the water to be treated and other factors decrease. The pH, ORP, and DO of the liquid to be treated are measured by the treated water quality measuring device 6, and the circulation amount of the raw water or the water to be treated is determined based on these values. Specifically, the amount of air blown in and other factors are adjusted so that the ORP is maintained at +10 mV or more in the aerobic reaction treatment section where the nitrification reaction occurs and at -10 mV or less in the anaerobic reaction treatment section where the denitrification reaction occurs, and the water to be treated is circulated. The circulation amount can be easily controlled by controlling the amount of air and / or the circulation rate control device without using a circulation pump or the like. Therefore, the wastewater treatment method of the present invention is an energy-saving wastewater treatment method. Furthermore, since the equipment including the microbial reaction tank of the present invention can adjust each unit of the microbial reaction individually, these controls can be preprogrammed and the equipment can be easily operated automatically without any personnel, making the equipment a labor-saving plant.

[0047] The circulation rate is controlled by the circulation rate control device 4, and some of the treated water and activated sludge discharged from the top of the cylindrical upper part 3c flow down the outer circumferential surface of a truncated cone with an inclination angle of about 45 degrees. The discharged treated water and activated sludge pass through the sludge thickening section 5b formed by the cylindrical control plate 5 arranged close to the inclined surface 3h of the truncated cone outer circumferential surface and the inclined surface 3h, enabling the activated sludge to be rapidly and forcibly settled. In addition, the purified treated water and activated sludge can be easily separated, and the separated treated water is discharged from the treated water discharge port 11. The activated sludge that has been forced to settle rapidly is deposited in the lower part of the outer tank 2 and on the lower periphery of the inclined surface 3h of the cylindrical upper part 3c. This deposited activated sludge is scraped off by the above-mentioned settling and immobilization prevention device 12, and while mixing with the water to be treated, it moves to the anaerobic microbial treatment reaction section and circulates within the microbial reaction tank. The wastewater treatment method of the present invention can easily absorb fluctuations in the load of raw water by circulating the activated sludge in the anaerobic-aerobic tank while thickening it at a circulation rate of 3 to 20. In addition, since the circulation rate is maintained within this range, the activated sludge is acclimatized to become the most suitable activated sludge for wastewater treatment.

[0048] In the microbial reactor, when the raw water has a low BOD load but a high nitrogen concentration, it is preferable to treat the water by adding denitrifying bacteria nutrients consisting of organic substances such as proton donors, for example, methanol, to the anaerobic reaction treatment section. In this case, since the pH of the treated water is likely to rise, it is preferable to add a mineral acid such as hydrochloric acid.

[0049] The wastewater treatment method using the microbial reaction tank of the present invention may use one microbial reaction tank, but may also use multiple tanks. In this case, the discharged water from the first tank is introduced into the raw water supply port of the second tank. In addition, for example, when two microbial reaction tanks are connected in series, wastewater treatment can be performed more effectively by changing the ratio of the volume of the nitrification reaction section to the volume of the denitrification reaction section in the second tank from that in the first tank. Specifically, denitrification and dephosphorization can be performed by making the volume ratio smaller than that in the first tank.

[0050] In addition, the wastewater treatment method using the microbial reactor of the present invention can be combined with conventional wastewater treatment methods. For example, in a wastewater treatment facility consisting of an existing aerobic nitrification tank and an anaerobic denitrification tank, the effluent from each tank can be supplied to the microbial reactor of the present invention to more effectively digest pollutants and remove nitrification and phosphorus. [Industrial Applicability]

[0051] The microbial reaction tank of the present invention can continuously perform anaerobic and aerobic microbial treatment while maintaining a high circulation rate within the tank, even when the capacity of the reaction tank is large, and can efficiently prevent activated sludge from accumulating within the tank, so it can be used as a wastewater treatment facility containing high concentrations of pollutants. [Explanation of symbols]

[0052] 1. Microbial Reactor 2 Outer tank 3 Cylindrical inner tank 4 Circulation rate control device 5 Cylindrical control plate 6. Treated water quality measuring device 7 Rotation Axis 8 Air Inlet 9 Support pillar 10 Raw water supply outlet 11 Treated water outlet 12 Sedimentation and fixation prevention device 13 First scraper 14 No. 2 scraper 15 Connecting members 16 Guide roller 17a Support stand 17b Guide part 17c Support roller 18 Support stand 19 Driven Wheel 20 Drive Chain 21 Geared motor 22 Shaft 23 Drive Wheel 24 Rail 25 Driving bogie 26 Connection parts 27 Sludge outlet

Claims

1. A microbial reaction tank comprising: an outer tank; a cylindrical inner tank disposed inside the outer tank and having openings at the top and bottom; a circulation rate control device disposed in the upper part of the cylindrical inner tank for controlling the circulation rate of the water to be treated within the tank; a cylindrical control plate disposed with its open lower surface in close proximity to an inclined surface on the upper outer periphery of the cylindrical inner tank for settling sludge; water quality measuring devices disposed on the outside and inside of the cylindrical inner tank; a raw water supply port disposed in a circulation path for the water to be treated circulating within the outer tank and the inner tank, and a treated water discharge port disposed in the upper part of the outer tank, The cylindrical inner tank is divided into an upper cylindrical portion and a lower cylindrical portion by a partition wall having a communicating hole at the center thereof, the cylindrical upper portion has a truncated cone-shaped top portion with an open top and bottom surface, the outer periphery of the top portion being the inclined surface, and a plurality of air inlets are provided around the communication holes and on the peripheral edge of the partition wall within the cylindrical upper portion; The lower part of the cylinder is an anaerobic microbial treatment tank having an opening on the bottom surface, agitation devices are provided for agitating the inside of the aerobic microbial treatment tank and the anaerobic microbial treatment tank, a settling and immobilization prevention device for preventing settling and immobilization of the settled sludge is provided in the outer tank, the settling and immobilization prevention device has a first scraper extending along the inclined surface of the upper part of the cylinder and a second scraper extending along the inclined inner surface of the lower part of the outer tank, the first scraper and the second scraper are connected to each other, and these rotate together in a circumferential direction within the outer tank; The circulation rate control device is provided with a means for detecting at least one measured value selected from the hydrogen ion concentration, oxidation-reduction potential and amount of dissolved oxygen of the water to be treated measured by the water quality measuring device, and a means for controlling the circulation rate of the water to be treated within a tank to 3 to 20 in accordance with the detected measured value, and the circulation rate control device is a device for controlling at least one amount selected from the opening and closing of a liquid level control valve, the up and down movement of a liquid level control plate, and the amount of air blown in from the air blowing port, The raw water supplied from the raw water supply port is circulated through the inside of the cylindrical inner tank, the outer circumferential surface of the cylindrical inner tank, and the activated sludge settled at the bottom of the outer tank, thereby continuously carrying out anaerobic microbial treatment and aerobic microbial treatment. The first scraper and the second scraper each have a plurality of plate members for scraping off the settled sludge, A microbial reaction tank characterized in that in each of the scrapers, the multiple plate members are arranged parallel to each other and fixed at an angle with respect to a plane perpendicular to the rotation direction.

2. 2. The microbial reaction tank according to claim 1, characterized in that in the cylindrical upper part of the cylindrical inner tank, the inclination angle of the inclined surface in a height direction cross section passing through the center of the truncated cone shape is 40 degrees to 60 degrees.

3. Each of the first scraper and the second scraper has the plurality of plate members, a fixing member that fixes the plurality of plate members, and a roller provided on the fixing member, The microbial reaction tank according to claim 1, characterized in that the first scraper moves on the inclined surface of the upper part of the cylinder by rolling of the roller, and the second scraper moves on the inclined inner surface of the lower part of the outer tank by rolling of the roller.

4. A driving means capable of rotating in a circumferential direction is disposed around the entire inner surface of the outer tank, 2. The microbial reaction tank according to claim 1, wherein the settling and immobilization prevention device is connected to the driving means and rotates circumferentially within the outer tank as the driving means rotates.

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