Patent Application
20210355009
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-086717, filed on May 18, 2020, and the entire contents of which are incorporated herein by reference.
An embodiment described herein relates generally to a water treatment apparatus and a water treatment system.
In water treatment systems that purify organic effluent containing organic matters such as sewage, biological treatment by microorganisms (hereinafter referred to as “microbial treatment”) is generally used. (The word microbial treatment may be referred as microorganism treatment)
One of the water treatment systems utilizing this type of microbial treatment is a water treatment system using a rotating disk process. (JP2007-301511A, JP2009-166038A)
It is known that domination of Bacillus bacteria allows the amount of excess sludge generated in the water treatment process to be reduced, generation of odor to be suppressed, and good organic matters and nitrogen removal performance can be obtained. It is also known that as disclosed in JP2000-189991A, when a biological reaction tank of the activated sludge process is placed in a subsequent stage of the water treatment process, the load of the biological reaction tank can be reduced, and it is therefore possible to achieve effects such as that the power consumption of the blower of the biological reaction tank can be significantly reduced.
On the other hand, if microorganisms excessively adhere to the disk-like flat plate, oxygen cannot be sufficiently supplied to the microorganisms inside of the disk-like flat plate, and contact between raw water and the microorganisms inside of the flat plate is hindered, and hence the water purification performance of the flat plate remarkably deteriorates.
Representative embodiments will be described below with reference to the drawings.
The embodiments are not limited to the following. In the following description, parts identical to previously described parts are indicated by using identical reference numerals, and duplicate description is avoided.
A water treatment apparatus 100 according to the first embodiment will be described.
A water treatment apparatus 100 is an apparatus that purifies raw water such as organic effluent (drainage) such as sewage, agricultural effluent, and industrial effluent by microbial treatment utilizing microorganisms such as Bacillus . As shown in
As shown in
A plurality of the flat plates 20 are placed in the water treatment tank 10 in parallel at a constant interval L. The flat plate 20 is a rotating disk body. Each flat plate 20 is installed in the water treatment tank 10 so that each flat plate 20 is not entirely immersed in raw water but a part of the lower side is immersed in the raw water w, and the upper side relative to the part immersed in the raw water w is in the gas phase. Thus, each flat plate 20 comes into contact with air on the upper side, and is immersed in the raw water w the lower side. Such a configuration is achieved by, for example, horizontally placing the rotary shaft 30 described later at a height substantially equal to the height of the upper edge of the water treatment tank 10. Thus, even if the water treatment tank 10 is filled with the raw water w, only the lower half of the flat plate 20 is immersed in the raw water w, and hence at least the upper half comes into contact with air. On the surface of each flat plate 20, a contact body for making microorganisms such as Bacillus bacteria to dominantly and easily adhere is placed. The contact body can be configured with a fibrous contact body, but the specific configuration is not particularly limited. The flat plate 20 may be porous so as to have a large number of microorganisms. Each flat plate 20 is provided with a through hole at the center of the circle. Microorganisms are planted in the contact body by adhering the microorganisms. For example, US 2010/0247837 A1 also mentions a contact body using microorganism, the entire contents of which are incorporated herein by reference.
The rotary shaft 30 is inserted into and fixed to a through hole at the center of the circle provided in each flat plate 20. The flat plates 20 are placed in parallel along the long axis direction of the rotary shaft 30 at the constant interval L.
The motor 40 rotates the rotary shaft 30 by a drive force. Thus, as shown by an arrow R shown in
The removal section 50 (remover) reduces the amount of the excessively adhering microorganisms so that the adhesion amount of the microorganisms adhering to the flat plate 20 is kept within an appropriate range. The removal section 50 includes a blower 51 and a diffuser tube 52, as an example of applying a physical action to the flat plate 20.
The blower 51 is provided outside the water treatment tank 10 and sends air to the diffuser tube 52 to be described later.
The diffuser tube 52 is installed below the flat plate in the water treatment tank 10. The surface of the diffuser tube 52 is provided with a multitude of small holes, and the air supplied from the blower 51 becomes bubbles when passing through the holes, rises in the raw water w, and collides with the flat plate 20 positioned above the diffuser tube 52, thereby applying a physical action. The microorganisms excessively adhering to the flat plate 20 are removed from the flat plate 20 by collision of bubbles from below or by upward flow generated by bubbles.
The sludge drawing pipe 60 is connected to the bottom surface of the water treatment tank 10.
The sludge drawing valve 70 is provided in the sludge drawing pipe 60. By the opening operation of the sludge drawing valve 70, the microorganisms accumulated at the bottom of the water treatment tank 10 are discharged from the water treatment tank 10 through the sludge drawing pipe 60. The opening operation of the sludge drawing valve 70 is performed by stopping the introduction of the raw water w into the water treatment tank 10. After the excessive microorganisms are discharged from the water treatment tank 10, the closing operation of the sludge drawing valve 70 is performed to resume (reopen) the introduction of the raw water w into the water treatment tank 10.
Next, the operation of the removal section 50 will be described.
The blower 51 of the removal section 50 operates by receiving a command to clean the flat plate 20. When the blower 51 of the removal section 50 operates, bubbles are generated from the holes of the diffuser tube 52, and it becomes possible to clean the flat plate 20.
Cleaning of the flat plate 20 with bubbles is carried out for a predetermined time (continuous cleaning is performed for several minutes). At the time of cleaning, the flat plate 20 is rotated. The rotation speed of the flat plate 20 at the time of cleaning may be freely set. It is desirable to stop the inflow of the raw water w into the water treatment tank 10 at the time of cleaning, but cleaning may be carried out while letting the raw water w flow into the water treatment tank 10. If the inflow of the raw water w to the water treatment tank 10 is stopped at the time of cleaning or after end of cleaning, the inflow of the raw water w is resumed at the end of cleaning.
The microorganisms exfoliated from the flat plate 20 by the removal section 50 may be recovered (collected) in the water treatment tank 10 and the microorganisms may be discharged from the sludge drawing pipe 60. The microorganisms exfoliated from the flat plate 20 by the removal section 50 may not be discharged from the sludge drawing pipe 60 because they are hydrolyzed as they are in the water treatment tank 10 and no excess sludge is generated.
The water treatment apparatus 100 according to the present embodiment becomes possible to remove microorganisms excessively adhering to the flat plate 20, and to stabilize the water treatment performance (prevent of deterioration of the treated water quality).
Further, the present embodiment provide a water treatment apparatus capable of reliably exfoliating excessively adhering microorganisms, dominating Bacillus bacteria, which is an effective microorganism, and always maintaining high treatment performance.
Since the amount of microorganisms excessively adhering to the flat plate 20 can be reduced by the removal section 50, the water treatment apparatus 100 according to the present embodiment becomes possible to reduce the workload of the maintenance manager of the water treatment facility and to save manpower.
In the modification 1 of the first embodiment, unlike the above-described first embodiment, the removal section has a water sprinkling mechanism.
Depending on the placement position of the water sprinkling section 151, the angle at which the fluid such as ejected water collides with the flat plate 20 can be changed. By reducing the angle at which the ejected fluid collides with the flat plate 20, excessive microorganisms can be exfoliated. In addition, the output of the sprinkler pump can increase the flow rate of the fluid, and it is hence possible to exfoliate a Spirogyra-like biofilm formed by microorganisms such as Sphaerotilus natans, which is difficult to be exfoliated by cleaning with bubbles in the first embodiment. In a case where the area of the flat plate 20 is large, uneven cleaning tends to occur in the fixed water sprinkling section 151 at only one place, and hence in order to uniformly clean the flat plate 20. For the reason, it is desirable to place a movable water sprinkling section 151 or a plurality of water sprinkling sections 151 at a plurality of locations.
The microorganisms exfoliated from the flat plate 20 may be recovered (collected) in the water treatment tank 10 and the microorganisms may be discharged from the sludge drawing pipe 60. The microorganisms exfoliated from the flat plate 20 may not be discharged from the sludge drawing pipe 60 because they are hydrolyzed as they are in the water treatment tank 10 and no excess sludge is generated.
Thus, according to the present modification, the removal effect in microorganism removal can be further enhanced, and the microbial films that have been difficult to be removed can be exfoliated from the flat plate 20.
In the modification 2 of the first embodiment, unlike the above-described first embodiment, the removal section has a scraping mechanism.
Note that ultrasonic cleaning, vibration, or the like may be applied as another microorganism removal mechanism for the flat plate 20. Alternatively, the above-described microorganism removal mechanism may be optionally combined and carried out. Thus, in the first embodiment, microorganisms are removed from the flat plate 20 by applying a physical action to the flat plate 20.
The second embodiment is to kill some of the microorganisms adhering to the flat plate 20 and reduces the amount of the microorganisms. That is, as a removal section of excessive microorganisms, a microorganism killing mechanism for killing excessive microorganisms on the flat plate 20 is provided.
The spores of Bacillus germinate in an environment with supply of food that is an organic matter and optimum temperature where ejection of the steam s by the steam ejection section 351 has ended, become nutrient cells, and start to purify water. The cumulative heating time is desirably 10 minutes or less per square centimeter. Too long heating time causes non-excessive microorganisms inside the flat plate 20 to be killed. The microorganisms killed by heating are naturally exfoliated from the flat plate 20 and decomposed by microorganisms in water or adhering to the flat plate 20.
In the present embodiment, by ejecting steam onto the surface of the flat plate 20, it becomes possible to save only microorganisms (Bacillus bacteria) useful for water treatment and to remove other excessive microorganisms.
Since it is possible to remove the microorganisms excessively adhering to the flat plate 20, it is possible to stabilize the water treatment performance (prevention of deterioration of treated water quality).
Furthermore, it is possible to reduce the workload of the maintenance manager of the water treatment facility (manpower saving).
In the modification 2 of the second embodiment, unlike the above-described second embodiment, the removal section has an ultraviolet irradiation mechanism.
In the modification 2 of the second embodiment, unlike the above-described second embodiment, the removal section has a sterilization agent charging mechanism.
The water treatment apparatus 600 according to the modification 2 of the second embodiment is effective when bulking occurs due to a large amount of filamentous fungi being generated in the flat plate 20 or the aeration tank in the subsequent stage of the water treatment tank 10, in particular. When a large amount of filamentous fungi is generated, the sedimentation property of sludge is remarkably lowered, separation of the treated water x and the sludge becomes difficult, and the quality of the treated water x deteriorates. When filamentous fungi adhere to the surface of the flat plate 20, they form a microbial film very difficult to be exfoliated. Enlargement of the biofilm causes the entire flat plate 20 to be covered, breathability and water permeability are lowered, thereby leading to lowering of water treatment performance. A polyethylenepolyamine dimethylamine epichlorohydrin polycondensation or the like, which is a sterilization agent effective for sterilization of filamentous fungi and has relatively little influence on other effective microorganisms, has already been developed. Charged by the sterilization agent charging mechanism described above, the sterilization agent can prevent deterioration of processing performance due to a large amount of filamentous fungi generated.
The modification 2 of the second embodiment can remove filamentous fungi that adversely affect water treatment.
Note that ultrasonic crushing, drying treatment, or the like may be applied as another microorganism killing mechanism for the flat plate 20. In addition, the microorganism killing mechanism of the second embodiment may be optionally combined and carried out. Furthermore, the microorganism removal mechanism of the first embodiment and the microorganism killing mechanism of the second embodiment may be optionally combined and carried out, and by combining them, excessive microorganisms can be removed more efficiently in a shorter time.
The third embodiment further includes an imaging section 82 (imaging device), and stops the function of the removal section 750 according to the image of the flat plate 20 imaged by the imaging section 82.
In the water treatment system 700 of the present embodiment, as illustrated in
As shown in
Note that
In the water treatment system 700, as in the first embodiment or second embodiment, due to the function of the removal section 750, reduces the amount of microorganisms adhering to the surface of the flat plate 20, and the intervals between the flat plates 20 adjacent to each other increases. Let the interval between the flat plates 20 adjacent to each other in a state where microorganisms do not adhere at all be L, and let the interval between the flat plates 20 adjacent to each other in a state where microorganisms adhere be ΔL(L>ΔL).
The imaging section 82 images such a state of the flat plate 20 from the upper side of the flat plate 20 in the gas phase section 81, and outputs image information g of the imaged flat plate 20 to a biological adhesion amount estimation section 91 (organism adhesion amount estimation section) of the control section 90 as shown in
The biological adhesion amount estimation section 91 of the control section 90 may perform image analysis on the image information g, may digitize the image information g to estimate the amount of microorganisms, and may stop the function of the removal section 750 of reducing the amount of microorganisms adhering to the flat plate 20. For example, when the removal section 750 kills microorganisms by steam heating, the protein contained in the microorganisms is discolored by heat. When this color change has a similar numerical value to that of a stop condition set in advance in a stop necessity determination section 92 (stop necessity judgment section) of the control section 90, the stop timing is controlled by using color information of the biofilm such as outputting a removal stop command (command to stop removal). When, for example, red, green, and blue in the RGB values match the set values as the color determination criteria, it is determined that the killing of the microorganisms is sufficient, and a removal stop command is output.
For example, a processor is used for the biofouling amount estimation section 91 and the stop necessity determination section 92. The processor consists of, for example, a CPU (Central Processing Unit). The biological adhesion amount estimation section 91 performs various processes based on a program or the like stored in memory or storage. In other words, the biological adhesion amount estimation section unit 91 and the stop necessity determination section 92 execute various programs as software function units. Instead of a CPU, an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array) may be used as a hardware functional part of the biological adhesion amount estimation section 91 and the stop necessity determination section 92. These can be used in place of the CPU. The same is true for the biological adhesion amount estimation section 191, 291, 391 and the stop necessity determination section 192, 292, 392.
The biological adhesion amount estimation section 91 of the control section 90 may perform image analysis on the image information g, may digitize the image information g to estimate the gap interval ΔL for each interval L. As described above, since the color tone of the image included in the image information g varies greatly depending on the presence or absence of microorganisms, the biological adhesion amount estimation section 91 can easily and accurately estimate the gap interval ΔL by using the difference in color tone.
The biological adhesion amount estimation section 91 can also estimate a film thickness b of the adhering microorganisms for each flat plate 20 by (L−ΔL)/2 on the basis of an assumption that the microorganisms proliferate uniformly even though some variation if any. Since the accuracy of the gap interval ΔL is high, the film thickness b is also estimated similarly with high accuracy.
The biological adhesion amount estimation section 91 outputs the intervals ΔL of all the gaps to the stop necessity determination section 92. Alternatively, instead of or in addition to the gap interval ΔL, the film thickness b may be output to the stop necessity determination section 92. Furthermore, the image information g may be output to a display section (not illustrated). This allows the operator to observe the image information g from the display section, and hence the operator can visually grasp the degree of adhesion of the microorganisms to the flat plate 20.
It should be noted that the digitization of the image information g does not necessarily have to be carried out by the biological adhesion amount estimation section 91. Instead of being carried out by the biological adhesion amount estimation section 91, the digitization of the image information g may be carried out by a function incorporated in the imaging section 82 or by another external computing device. If the imaging section 82 or another external computing device performs digitization, the imaging section 82 or another external computing device having performed the digitization outputs the result of the digitization to the biological adhesion amount estimation section 91. By using the result of the digitization, the biological adhesion amount estimation section 91 determines the gap interval ΔL and the film thickness b calculated from the gap interval ΔL as mentioned above for each interval L.
The stop necessity determination section 92 sums up the intervals ΔL of all the gaps having been output from the biological adhesion amount estimation section 91. Then, if the result of the sum is equal to or greater than a predetermined value, it is determined that the removal section 750 has removed the microorganisms excessively adhering to the flat plate 20, and a removal stop command is output to the removal section 750.
Alternatively, the stop necessity determination section 92 may select a representative gap interval ΔL from the gap intervals ΔL having been output from the biological adhesion amount estimation section 91, and if the selected gap interval ΔL is equal to or greater than a predetermined value, the stop necessity determination section 92 may determine that the removal section 750 has removed the microorganisms excessively adhering to the flat plate 20, and may output a removal stop command.
As an example of a case of selecting a representative gap interval ΔL, for example, on the above-described assumption that the microorganisms proliferate uniformly even though some variation if any, a void interval ΔL4 between two adjacent flat plates 20-4 and 20-5 existing on the center side in the water treatment system 700 can be selected as the representative void interval ΔL.
Alternatively, a gap interval ΔL1 between the left-most flat plate 20-1 and the flat plate 20-2 second from the left in
If the selected gap interval ΔL is equal to or greater than a predetermined value, the stop necessity determination section 92 outputs a removal stop command that stops the function of the removal section 750 to reduce the amount of microorganisms adhering to the flat plate 20.
As an example of a specific determination criterion for removal section stop necessity based on a single gap interval ΔL, if the interval L between the flat plates 20 adjacent to each other is 5 cm, a removal stop command is output when the gap b interval ΔL becomes 4 cm or more.
As described above, the water treatment system 700 of the present embodiment can determine the necessity of stopping the function of the removal section 750 in accordance with the gap interval ΔL and the film thickness b estimated based on the image information g imaged by the imaging section 82.
In the water treatment system 700, the imaging section 82 is placed in the gas phase section 81 and images the state of the flat plate 20 from the gas phase section 81, and hence the imaged image information g is clear. Therefore, the gap interval ΔL and the film thickness b can be estimated with high accuracy, and it becomes possible for the stop necessity determination section 92 to determine the removal stop necessity with high reliability.
Since the imaging section 82 is placed not in water but in the gas phase section 81, the cleaning of the imaging section 82 only requires automatic cleaning by a wiper, and can be operated almost without maintenance.
Furthermore, since the image information g can be displayed on the display section such as a display, the operator of the water treatment system 700 can visually grasp the degree of adhesion of the microorganisms to the flat plate 20 by confirming the image information g displayed on the display section.
Thus, as in the water treatment system 700 of the present embodiment, by providing a configuration including the imaging section 82 and determining, in accordance with the image information g, whether or not the amount of microorganisms excessively adhering to the flat plate 20 has been successfully removed by the function of the removal section 750, it becomes possible to reduce the maintenance management cost, to save labor, to improve the efficiency of operation, and to simplify the configuration without generating an extra maintenance labor by introducing the imaging section 82.
The modification 1 of the third embodiment is, unlike the above-described third embodiment, a water treatment system 800 that stops the function of the removal section in accordance with the current measured by the ammeter.
As the amount of microorganisms adhering to the flat plate 20 is reduced, the torque when rotating the flat plate 20 is lowered. Therefore, as illustrated in
Based on the relationship illustrated in
The operator can confirm the film thickness b estimated by the biological adhesion amount estimation section 191 from the display section.
If the current value from the biological adhesion amount estimation section 191 is lower than the removal stop determination current value shown in
The modification 2 of the third embodiment is, unlike the above-described third embodiment, a water treatment system that stops the function of the removal section in accordance with the distance measured by the distance meter.
The biological adhesion amount estimation section 291 estimates the adhesion amount of microorganisms based on the measurement result from the laser distance meter 83. Since the location where the laser distance meter 83 is provided is known, the distance and direction from the laser distance meter 83 to the representative flat plate 20-4 are also known in advance. This direction corresponds to an irradiation angle θ (angle with respect to the vertical direction) shown in
Based on the estimated film thickness b, the stop necessity determination section 292 determines the necessity of stopping the function of the removal section 750 to reduce the amount of the microorganisms excessively adhering to the flat plate 20. Since the other configurations are as described above, the description is omitted.
Thus, according to the present modification, the laser distance meter 83 or a photoelectric distance sensor can also be applied.
In order to acquire information necessary for estimating the film thickness b of the microorganisms adhering to the flat plate 20, the imaging section 82, the laser distance meter 83, and a photoelectric distance sensor 84 may be applied together.
The modification 3 of the third embodiment is, unlike the above-described third embodiment, a water treatment system stops the function of the removal section in accordance with the distance measured by the imaging section, the distance meter, and the photoelectric distance sensor.
The imaging section 82 outputs the image information g to a biological adhesion amount estimation section 391 of a control section 390. As described above, the laser distance meter 83 outputs, to the biological adhesion amount estimation section 391, the distance to the surface of the representative flat plate 20-4, which is the measurement result.
The photoelectric distance sensor 84 outputs, to the biological adhesion amount estimation section 391, the distance to the surface of the representative flat plate 20-6, which is the measurement result.
As described above, the biological adhesion amount estimation section 391 estimates the film thickness b from the image information having been input from the imaging section 82. As described above, the biological adhesion amount estimation section 391 also estimates film thickness b from different measurement results having been input from the laser distance meter 83 and the photoelectric distance sensor 84.
In this manner, the biological adhesion amount estimation section 391 can estimate three film thicknesses b at the same time. Then, the three film thicknesses b estimated at the same time are all output to a stop necessity determination section 392.
The stop necessity determination section 392 outputs a removal stop command if any value or the average value of the three film thicknesses b having been output at the same time is smaller than a predetermined value.
Such a configuration can determine a state in which the amount of microorganisms excessively adhering to the flat plate 20 has been reduced, and can output a removal stop command to the removal section 750. Even when any of the imaging section 82, the laser distance meter 83, and the photoelectric distance sensor 84 break down, it is possible to estimate the film thickness b of the microorganisms, and output a removal stop command where necessary.
The case where all of the imaging section 82, the laser distance meter 83, and the photoelectric distance sensor 84 are used has been described above, but any two of them may be used. The configuration in which two of the imaging section 82, the laser distance meter 83, and the photoelectric distance sensor 84 are used can also estimate the film thickness b of the microorganisms and can output a removal stop command even if one of them fails.
Thus, according to the first to third embodiments, it is possible to provide a water treatment apparatus 100, 200, 300, 400, 500, 600 and a water treatment system 700, 800, 900, 999 that can remove, such as reliably exfoliate (peel off) or kill, microorganisms excessively adhering to the surface of a flat plate 20, and cause the flat plate to maintain a high removal rate at all times with respect to an object to be removed such as organic matters, nitrogen, and phosphorus by bringing oxygen and raw water into contact with microorganisms inside of the flat plate 20.
Although some embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-086717 | May 2020 | JP | national |
