JP2006088047A - Water treatment method and equipment therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment method and equipment therefor which hardly cause wear of carriers and are capable of highly retaining the activity of the carriers and maintaining stable treatment performance. <P>SOLUTION: The water treatment equipment is provided with a reaction tank 10 in which the granular carriers 16 with microorganisms entrapped/fixed therein are made to flow, water 12 to be treated is caused to contact with the carriers and, thereby harmful components in the water 12 to be treated are biologically treated and are removed, a pump 25 which extracts a part of the carriers 16 from the reaction tank 10, a carrier storage tank 26 which stores extracted carriers 16 and a stop valve 30 which feeds stored carriers 16 to the reaction tank 10. The harmful components in the water 12 to be treated flowing into the reaction tank 10 are detected by a detection meter 36, and the extraction and feeding of the carriers are controlled, by a controller 38 in accordance with a load of the harmful components. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a water treatment method and apparatus, and more particularly, to a water treatment method and apparatus for biologically treating and removing harmful components in water to be treated using a granular carrier on which microorganisms are immobilized.

  In order to address the problem of eutrophication in closed waters, it is highly desirable to remove nitrogen in the influent wastewater. Nitrogen is mainly contained in sewage and various industrial wastewater in the form of ammoniacal nitrogen. Biological methods are generally employed as methods for removing ammoniacal nitrogen from wastewater. This method uses nitrifying bacteria to oxidize ammonia nitrogen to nitrite and nitric acid, and then uses denitrifying bacteria to convert nitrous acid and nitric acid to nitrogen gas for removal.

Because nitrifying bacteria have a slow growth rate, in order to perform stable nitrogen removal, it is necessary to perform low-load operation in the nitrification reaction tank with a nitrogen load of 0.2 to 0.4 kg-nitrogen / m ³ / day. There is an increase in the size of the nitrification reaction tank. As a countermeasure against this, a method of keeping a high concentration of nitrifying bacteria by introducing a carrier in which nitrifying bacteria are comprehensively immobilized into a nitrification reaction tank is becoming widespread. According to this method, high-speed processing in which the nitrification reaction tank is miniaturized becomes possible.

In order to maintain not only nitrifying bacteria but also organic matter-degrading bacteria, environmental hormone-degrading bacteria, etc. at a high concentration and perform high-speed processing, a carrier in which these microorganisms are comprehensively immobilized is used on a practical scale or researched and developed. . This type of carrier is usually formed in a granular form, and is used in a state where it is mixed and stirred with the water to be treated mechanically or by aeration in order to increase the contact efficiency with the water to be treated. As the carrier material, a polymer gel is mainly used (for example, see Patent Document 1 and Patent Document 2).
Japanese Patent No. 3389811 Japanese Patent No. 3514360

  However, since the above-mentioned carrier is vigorously mixed and agitated with the water to be treated, it is gradually worn out over a long period of operation. In particular, a carrier in which microorganisms are entrapped and immobilized using a polymer gel is highly worn. Further, when the carrier is used under a low load condition for a long time, the microorganisms in the carrier are self-degraded and reduced, and the activity is lowered. As a result, there is a problem that the original advantage of high-speed processing while maintaining a high concentration of microorganisms is diminished.

  The object of the present invention is to provide a water treatment method and apparatus capable of improving the above-mentioned problems of the prior art, reducing the wear of the carrier, maintaining the activity of the carrier high, and maintaining stable treatment performance. There is to do.

  In order to achieve the above object, a water treatment method according to the present invention supplies treated water to a reaction tank in which a granular carrier in which microorganisms are entrapped and immobilized flows, and the fluidized carrier and treated water are brought into contact with each other. In the water treatment method for biologically treating and removing harmful components in the water to be treated, the amount of the carrier flowing in the reaction tank is controlled according to the load of the harmful components.

  In the above method, a part of the carrier is withdrawn from the reaction tank if the load of the harmful component is not more than a lower limit value, and if the load of the harmful component is not less than the upper limit value or the quality of treated water is not less than a reference value, the withdrawal is performed. It is desirable to put the existing carrier into the reaction vessel. When the harmful component is a nitrogen component, it is desirable to set the lower limit of the load of the nitrogen component to less than 50 mg-nitrogen / h / L-carrier.

  Further, the water treatment apparatus according to the present invention biologically treats and removes harmful components in the water to be treated by flowing a granular carrier in which microorganisms are comprehensively immobilized and bringing the water to be treated into contact with the carrier. It is characterized by comprising a reaction tank and a carrier amount adjusting means for adjusting the amount of the carrier that flows in the reaction tank according to the load of the harmful component.

  The carrier amount adjusting means includes a carrier extracting means for extracting a part of the carrier from the reaction tank, a carrier storing means for storing the carrier extracted by the carrier extracting means, and a carrier stored in the carrier storing means. It is desirable that it is constituted by a carrier charging means for charging into the reaction tank. In addition, a monitoring means for monitoring the quality of the treated water flowing into the reaction tank and / or the treated water discharged from the reaction tank is provided, and the carrier amount adjusting means is controlled based on the monitoring result by the monitoring means. It is desirable to have done.

  According to the present invention, when the load of harmful components is low, control is performed so as to reduce the amount of carrier flowing in the reaction tank. For this reason, the carrier that is not fluidized is not subjected to air aeration or agitation during that period, and wear of the carrier can be reduced. In addition, the load of harmful components on the carrier is always kept in an appropriate range in the reaction tank, and the biological activity can be kept high and the biological treatment can be continued.

The carrier according to the present invention can be obtained by mixing a monomer material or prepolymer material and a microorganism and solidifying the mixed solution. As a solidifying method, polymerization, ion supply, crystallization and the like are preferable. As the monomer material, acrylamide, methylenebisacrylamide, triacryl formate and the like are preferable. As the prepolymer material, polyethylene glycol diacrylate and polyethylene glycol methallyllate are good, and derivatives thereof can also be used. The carrier is formed into a spherical shape, a square shape or a cylindrical shape, and the size is preferably 1 to 10 mm as a sphere equivalent diameter. For example, in the case of nitrifying bacteria, the concentration of microorganisms to be immobilized exhibits activity when the number of nitrifying bacteria is 10 ⁶ / mL-carrier or more. When the number of nitrifying bacteria at the time of production is 10 ⁵ / mL-carrier or more, it grows to 10 ⁸ cells / mL-carrier or more inside the carrier by appropriate habituation.

  Microorganisms to be immobilized are activated sludge, nitrifying bacteria group, denitrifying bacteria group, anaerobic ammonia oxidizing bacteria group and other complex microorganisms, or nitrifying bacteria, denitrifying bacteria, anaerobic ammonia oxidizing bacteria, blue-green-decomposing bacteria, PCB-degrading bacteria, There are pure bacteria such as dioxin-degrading bacteria and environmental hormone-degrading bacteria.

The basic experiment results using such a carrier will be described below. Nitrifying bacteria were used as microorganisms to be immobilized. That is, persulfuric acid as a polymerization agent in a suspension obtained by mixing 30 parts of a nitrifying bacteria concentrate (10 ⁹ bacteria / mL), 10 parts of polyethylene glycol diacrylate, 0.5 part of tetramethylethylenediamine, and 59.25 parts of water. When 0.25 part of potassium is added, polymerization starts and gelation occurs. This gel was cut into cubes having a side of 3 mm, and used as a carrier for basic experiments.

Experiment 1 (Abrasion characteristics experiment)
The following acceleration experiment was performed assuming wear of the carrier due to collision between the reaction vessel wall surface (made of concrete or steel plate) and the carrier. That is, sandpaper was pasted on the wall surface of a water tank with a stirrer having an effective volume of 2 L, and 2 L of water and 200 mL of carrier were added. Stirring was carried out at a rotational speed of the stirrer of 60 rpm, and changes in the volume of the carrier were examined. FIG. 5 shows the experimental results. As indicated by line A, the volume of the carrier decreases linearly with the passage of days. On the other hand, from the 50th day to the 100th day, the carrier is extracted from the water tank and stored, and the result of the same stirring in the water tank again from the 100th day is shown by a line B. From this experimental result, it was found that the carrier was worn out by long-term stirring and gradually reduced in volume, and when the carrier was extracted and stored, the wear was reduced accordingly, and the life could be extended.

Experiment 2 (Air aeration experiment)
Carriers with sufficient growth of nitrifying bacteria (10 ⁸ nitrifying bacteria / mL-carrier) by acclimation were aerated in fresh water without nutrients, and changes in the number of nitrifying bacteria were examined. For comparison, the case where the carrier was drained and stored at a predetermined temperature was also examined. FIG. 6 shows the experimental results. In FIG. 6, line C shows the case where air is aerated, line D shows the case where it is stored at 20 ° C., and line E shows the case where it is stored at 5 ° C. Air aeration reduces the number of nitrifying bacteria in the carrier with a half-life of 4 days. This is because nitrifying bacteria self-decomposed by air aeration. On the other hand, when stored without aeration, there is little decrease in the number of bacteria, especially when stored at 5 ° C., the number of bacteria hardly decreases.

Experiment 3 (Experiment of bacterial growth inside the carrier)
Was charged immediately after production carrier (nitrifying bacteria number 10 ⁵ / mL-carrier) in the raw water ammonia nitrogen concentration 100 to 400 mg / L, varying the nitrogen component load 10~313mg-N / h / L- carrier The growth status of nitrifying bacteria after 1 month of culture in each load was examined. FIG. 7 shows the experimental results. When the nitrogen component load is as low as 10 or 21 mg-N / h / L-carrier, the number of nitrifying bacteria hardly grows. In order to increase the number of nitrifying bacteria exhibiting activity as 10 ⁶ carriers / mL-carrier or more, the nitrogen component load is 33 mg-N / h / L-carrier or more, preferably about 50 mg-N / h / L-carrier. It turns out that it should be retained.

  The present invention has been made based on the above-described basic experimental results. FIG. 1 is an apparatus system diagram showing a first embodiment of the present invention. The reaction tank 10 has an inlet for treated water 12 and an outlet 15 for treated water 14. In addition, a granular carrier 16 in which microorganisms are comprehensively immobilized is placed in the reaction tank 10. The total amount of the carrier 16 is about 5 to 25% with respect to the effective volume of the reaction vessel 10. When the immobilized microorganism is an aerobic microorganism such as nitrifying bacteria, air is sent from the blower 20 to the air diffuser 18 disposed at the bottom of the reaction tank 10 to aerate the inside of the reaction tank 10. Due to this aeration energy, the water 12 to be treated and the carrier 16 that have flowed and flowed in are vigorously mixed and contacted. As a result, harmful components to be removed in the treated water 12 come into contact with the microorganisms immobilized on the carrier 16, and the harmful components are decomposed or oxidized and removed by the biological action of the microorganisms. When the immobilized microorganism is an anaerobic microorganism such as denitrifying bacteria, the carrier 16 is caused to flow by using a stirrer instead of the aeration means 18 or blowing an inert gas into the reaction tank 10. .

  A screen 22 is provided on the outlet 15 side of the reaction tank 10, and the carrier 16 and the treated water 14 are separated by this screen 22. The reaction tank 10 is connected to a carrier extraction pipe 24 having a pump 25, and the other end of the extraction pipe 24 is connected to a carrier storage tank 26. It is desirable to place the carrier storage tank 26 in a refrigeration facility and place it in an environment of about 5 ° C. The water to be treated and the carrier 16 drawn out from the reaction tank 10 by the pump 25 are sent to the upper part of the carrier storage tank 26, and the carrier 16 is stored by sinking downward. The water to be treated separated from the carrier 16 is returned to the reaction tank 10 through the overflow tank 28. A carrier input pipe 32 having an automatic opening / closing valve 30 is connected to the bottom of the carrier storage tank 26, and the other end of the carrier input pipe 32 is connected to the reaction tank 10.

  A detector 36 for detecting the concentration of harmful components in the water to be treated is disposed in the inflow pipe 34 of the water to be treated. The detection value of the detector 36 is transmitted to the controller 38, and the controller 38 calculates the load of harmful components in the reaction tank 10 based on the detected value of the concentration of harmful components in the treated water transmitted from the detector 36. . Further, when the amount of the carrier charged in the reaction tank 10 is known, the load of harmful components on the carrier is also calculated. Then, the controller 38 controls the driving of the pump 25 that is the carrier drawing means and the opening and closing of the automatic on-off valve 30 that is the carrier loading means according to the calculated loads of these harmful components.

  That is, if the load of harmful components is equal to or lower than the lower limit value, the controller 38 temporarily drives the pump 25 to pull out a part of the carrier 16 put in the reaction tank 10 from the reaction tank 10 and pull it out. The carrier 16 is fed into the carrier storage tank 26. In the carrier storage tank 26, the fed carrier 16 is temporarily stored. If the load of harmful components is not less than the upper limit value, the automatic opening / closing valve 30 is temporarily opened, and at least a part of the carrier 16 stored in the carrier storage tank 26 is put into the reaction tank 10. It should be noted that the amount of the carrier 16 to be pulled out and charged is about 3 to 5% of the total amount of the carrier. Since the capacity of the carrier storage tank 26 is limited, it is preferable to limit the maximum amount of the carrier 16 stored in the carrier storage tank 26 to, for example, about 20 to 40% of the total carrier amount. If the load of harmful components is between the lower limit value and the upper limit value, the current operation is continued without pulling out and loading the carrier 16 described above.

According to the first embodiment, when the load of harmful components is equal to or lower than the lower limit value, a part of the carrier 16 is pulled out from the reaction tank 10 and stored in the carrier storage tank 26. For this reason, in the reaction tank 10, the load of harmful components per unit volume of the carrier is increased accordingly, and it is possible to avoid air aeration and a low load state. For this reason, the fall of the activity of the support | carrier 16 in the reaction tank 10 can be prevented. Further, when the load of harmful components is equal to or higher than the upper limit value, the extracted carrier 16 is returned to the reaction vessel 10. For this reason, in the reaction tank 10, the load of harmful components per unit volume of the carrier is always maintained within an appropriate range, and stable biological treatment can be continued. Further, since the carrier 16 stored in the carrier storage tank 26 is left in an environment of about 5 ° C. without being subjected to air aeration or agitation during the storage period, the activity is not reduced or worn. For this reason, according to the method and apparatus of this embodiment, it is possible to realize a water treatment in which the carrier is less worn and the activity of the carrier is kept high and a stable treatment performance is maintained. When the harmful component is ammonia nitrogen, it is desirable to set the lower limit of the nitrogen component load to 30 to 50 mg-nitrogen / h / L-carrier. That is, as shown in FIG. 7, in the vicinity of the nitrogen component load of 30 to 50 mg-nitrogen / h / L-carrier, the carrier 16 has a number of nitrifying bacteria of about 10 ⁶ to 10 ⁷ cells / mL-carrier, There is enough activity. By extracting and storing the carrier 16, the activity can be maintained high during the storage period. For this reason, when the reaction vessel 10 is recharged, the activity can be immediately exhibited.

  FIG. 2 is an apparatus system diagram showing a second embodiment of the present invention. In FIG. 2, elements denoted by the same reference numerals as those in FIG. 1 are the same elements as in FIG. In this 2nd Embodiment, the water quality meter 40 which monitors the quality of the treated water is arrange | positioned at the discharge port 15 of the treated water, and the detected value of the water quality meter 40 is transmitted to the controller 38A. In the controller 38A, based on the detected value of the harmful component concentration in the for-treatment water transmitted from the detector 36 and the detected value of the treated water transmitted from the water quality meter 40, the driving of the pump 25 which is the carrier drawing means, It controls the opening / closing of the automatic opening / closing valve 30 which is a carrier loading means.

  FIG. 3 is a flowchart showing an example of control in this embodiment. First, in step S100, the detection value of the water quality meter 40 is transmitted to the controller 38A. If the water quality of the treated water is appropriate (the drainage standard value or less), the process proceeds to the next step S110. Further, if the quality of the treated water is inappropriate (over the drainage standard value), it is determined that the amount of the carrier in the reaction tank 10 is insufficient, and the controller 38A controls to put the carrier into the reaction tank 10. (S120). In step S110, the load of the harmful component in the reaction tank 10 is calculated based on the detected value of the harmful component concentration in the for-treatment water transmitted from the detector 36. In addition, when the amount of the carrier accommodated in the reaction tank 10 is known, the load of harmful components on the carrier is also calculated. Then, if the load of these harmful components calculated by the controller 38 is equal to or lower than the lower limit value, the controller 38 temporarily drives the pump 25 to remove a part of the carrier 16 accommodated in the reaction tank 10. The carrier 16 pulled out from the reaction tank 10 is sent to the carrier storage tank 26 (S130). Note that the amount of the carrier 16 withdrawn and charged is set to about 3 to 5% of the total amount of carrier as in the first embodiment. Further, the maximum amount of the carrier 16 stored in the carrier storage tank 26 is also limited to about 20 to 40% of the total carrier amount. Therefore, if the stored carrier 16 has reached the maximum amount, the current operation is continued without being pulled out even if the load of harmful components is below the lower limit value in step S110.

  Further, if the load of harmful components exceeds the lower limit value, the current operation is continued. Thereafter, the same control is repeated at a frequency of once every several hours in the same procedure. If the quality of the treated water flowing in is severe, calculating the load of harmful components based on the detection value of the detector 36 at each time point causes the calculated value to fluctuate with the quality of the treated water, resulting in poor control. Become stable. Therefore, when calculating the load of harmful components, it is desirable to use a value obtained by averaging the detection value of the detector 36 in a predetermined time zone (for example, control interval time).

  According to the second embodiment, the water quality of the treated water 14 is monitored, and if the water quality is inappropriate (over the drainage standard value), the carrier is introduced into the reaction tank 10. Water quality can be stabilized.

  The present invention is not limited to the first embodiment or the second embodiment. For example, it is possible to omit the water quality monitoring of the treated water 12 and the treated water 14 and the automatic control system of the controllers 38 and 38A. That is, the present invention also includes a configuration in which the operator manually operates the carrier extraction means and the carrier input means based on the result of the water quality inspection by periodic sampling of the treated water 12 and the treated water 14.

  Further, as the carrier drawing means, an air lift type pump may be employed instead of the spiral type pump 25 shown in FIGS. Various pumps may be adopted as the carrier loading means in place of the automatic opening / closing valve 30 shown in FIGS. Furthermore, the carrier amount adjusting means according to the present invention is not limited to the one constituted by the carrier extracting means, the carrier storing means, and the carrier loading means shown in the first and second embodiments.

  FIG. 4 is an apparatus system diagram showing a third embodiment of the present invention. In FIG. 4, elements denoted by the same reference numerals as those in FIG. 1 are the same elements as in FIG. A partition wall 42 having an open upper end and a lower end is provided in the reaction tank 10. The left area partitioned by the partition wall 42 is a storage area 44 of the carrier 16 as the carrier amount adjusting means, and the left side surface of the storage area 44 is a steeply inclined surface. In addition, the right area partitioned by the partition wall 42 is a flow area 45 of the carrier 16. An opening / closing door 46 that slides in the vertical direction is provided on the lower end side of the partition wall 42. FIG. 4 shows a state in which the opening / closing door 46 is tightened, and a part of the carrier 16 flowing in the flow area 45 gets over the upper end of the partition wall 42 and enters the storage area 44 and sinks. Temporarily stored at the bottom. When the opening / closing door 46 is pulled up and opened, the carrier 16 stored in the storage area 44 flows into the flow area 45 and flows in the same manner as the other carriers 16 in the flow area 45 to be subjected to biological treatment of the object to be processed. Contribute.

  Since the carrier 16 stored in the storage area 44 does not flow and is not aerated during the storage period, it does not wear and does not decrease its activity. The amount of the carrier 16 stored in the storage area 44 can be adjusted by adjusting the opening degree or opening / closing frequency of the opening / closing door 46. In other words, it is possible to adjust the amount of the carrier that flows in the reaction vessel 10. Therefore, by controlling the amount of carrier that flows in the reaction vessel 10 according to the load of harmful components to a suitable amount, the wear of the carrier is kept low and the activity of the carrier is kept high, thereby maintaining stable processing performance. be able to.

Example 1
As a polymerization agent, a suspension obtained by mixing 50 parts of a nitrifying bacteria concentrate (10 ⁹ bacteria / ml), 4 parts of polyethylene glycol diacrylate, 1 part of acrylamide, 0.5 part of tetramethylethylenediamine, and 44.25 parts of water When 0.25 part of potassium persulfate is added, polymerization starts and gelation occurs. This gel was cut into a cube having a side of 3 mm, and used as an experimental carrier. The experimental conditions are as follows.
Experimental apparatus Water to be treated as shown in FIG. 1 BOD about 10 mg / L, ammoniacal nitrogen 32 to 280 mg / L
Retention time of water to be treated in reaction tank 8 hours Carrier filling rate in reaction tank 20%
Nitrogen loading on carrier 20-175 mg-nitrogen / h / L-carrier Continuous treatment under the conditions described above. The quality of the water to be treated was large and the nitrogen load was initially operating at 120 mg-nitrogen / h / L-carrier, but then the nitrogen load dropped to 30 mg-nitrogen / h / L-carrier. Then, the extraction of the carrier was started. When 40% of the carrier was drawn out with respect to the total amount of the carrier, the drawing was stopped, and the drawn carrier was stored at room temperature. Thereafter, the entire amount of the carrier extracted when the nitrogen load exceeded 100 mg-nitrogen / h / L-carrier was reintroduced into the reaction vessel. In this way, the operation of drawing out the carrier with a nitrogen load of 30 mg-nitrogen / h / L-carrier and repeating the operation with the nitrogen load of 100 mg-nitrogen / h / L-carrier was repeated. As a result, the wear rate of the carrier is 2% per year, and the wear rate of the carrier is significantly reduced compared to the annual wear rate of 3% when not pulled out and stored, and the life against the wear of the carrier is 1.5 times longer. did. Moreover, when not carrying out extraction storage, the ammonia nitrogen concentration of the treated water fluctuated in the range of 4 to 24 mg / L. On the other hand, when the carrier was pulled out and re-introduced, the ammonia nitrogen concentration of the treated water was 4 to 8 mg / L, and stable treated water could be obtained.

Example 2
The same carrier used in Example 1 was used as an experimental carrier. The experimental conditions are as follows.
Experimental apparatus Water to be treated as shown in FIG. 2 BOD about 10 mg / L, ammoniacal nitrogen 124-280 mg / L
Retention time of water to be treated in reaction tank 8 hours Carrier filling rate in reaction tank 20%
Nitrogen loading on carrier 78-175 mg-nitrogen / h / L-carrier
(Plan load 140mg-nitrogen / h / L-carrier)
Continuous treatment was performed under the conditions described above. The criteria for determining the ammoniacal nitrogen concentration of the treated water was set to 5 mg / L, and the extraction of the carrier was started at 5 mg / L or less. When 40% of the carrier was drawn out with respect to the total amount of the carrier, the drawing was stopped, and the drawn carrier was stored at room temperature. When the ammoniacal nitrogen concentration exceeded 5 mg / L, the entire amount of the carrier extracted was reintroduced into the reaction vessel. Thus, the operation | movement which repeats drawing | extracting and reintroducing of a support | carrier was performed. As a result, the wear rate of the carrier is 2% per year, and the wear rate of the carrier is significantly reduced compared to the annual wear rate of 3% when not pulled out and stored, and the life against the wear of the carrier is 1.5 times longer. did.

Example 3
Anaerobic ammonium oxidizing bacteria concentrate (a few 10 ⁹ bacteria / mL) 34 parts, 6 parts of polyethylene glycol diacrylate, 0.5 parts of tetramethylethylenediamine as a polymerization agent mixture suspension water 59.25 parts over When 0.25 part of potassium sulfate is added, polymerization starts and gelation occurs. This gel was cut into a cube having a side of 3 mm, and used as an experimental carrier. The experimental conditions are as follows.
Experimental apparatus Similar to that shown in FIG. However, by stirring the inside of the reaction tank without performing aeration by the aeration means, the inside of the tank is maintained under anaerobic conditions, and the water to be treated is 300 mg / L for ammonia nitrogen and 260 mg / L for nitrite nitrogen.
Residence time of water to be treated in reaction tank 4 hours Carrier filling rate in reaction tank 15%
Continuous treatment was performed under the conditions described above. The criterion for determining the total nitrogen concentration of the treated water was set to 80 mg / L, and the extraction of the carrier was started at 80 mg / L or less. When the carrier was drawn 30% of the total amount of the carrier, the drawing was stopped, and the drawn carrier was stored at 5 ° C. When the total nitrogen concentration exceeded 100 mg / L, the entire amount of the extracted carrier was reintroduced into the reaction vessel. Thus, the operation | movement which repeats drawing | extracting and reintroducing of a support | carrier was performed. As a result, the wear rate of the carrier is 4% per year, and the wear rate of the carrier is significantly reduced compared to the annual wear rate of 6% when not withdrawn and stored, and the life against the wear of the carrier is increased by 1.5 times. did.

1 is an apparatus system diagram showing a first embodiment of the present invention. It is an apparatus system diagram which shows 2nd Embodiment of this invention. It is a flowchart which shows the example of control in 2nd Embodiment. It is an equipment distribution diagram showing a 3rd embodiment of the present invention. 6 is a graph showing an experimental result of Experiment 1. 10 is a graph showing an experimental result of Experiment 2. 10 is a graph showing an experimental result of Experiment 3.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ......... Reaction tank, 12 ......... Water to be treated, 14 ......... Treatment water, 16 ...... Carrier, 18 ......... Air diffuser, 20 ...... Blower, 22 ...... Screen, 24 ... ...... Carrier extraction pipe, 25 ......... Pump, 26 ......... Carrier storage tank, 28 ......... Overflow tank, 30 ......... Automatic open / close valve, 32 ......... Carrier input pipe, 34 ......... Inflow pipe 36 ......... Detector, 38, 38A ......... Control, 40 ......... Water quality meter, 42 ......... Partition wall, 44 ......... Storage area, 45 ......... Flow area, 46 ......... Opening and closing door.

Claims (6)

  The water to be treated is supplied to a reaction vessel in which a granular carrier in which microorganisms are entrapped and immobilized flows, and the fluidized carrier and the water to be treated are brought into contact with each other to biologically treat harmful components in the water to be treated. In this water treatment method, the amount of carrier fluidized in the reaction vessel is controlled in accordance with the load of the harmful component.   If the load of harmful components is lower than the lower limit, a part of the carrier is withdrawn from the reaction tank, and if the load of harmful components is higher than the upper limit or the quality of treated water is higher than the reference value, the extracted carrier is reacted. The water treatment method according to claim 1, wherein the water treatment method is performed in a tank.   The water treatment method according to claim 2, wherein the harmful component is a nitrogen component, and the lower limit of the load of the nitrogen component is less than 50 mg-nitrogen / h / L-carrier.   A reaction vessel that biologically treats and removes harmful components in the water to be treated by flowing a granular carrier in which microorganisms are comprehensively immobilized and bringing the water to be treated into contact with the carrier, and depending on the load of the harmful components And a carrier amount adjusting means for adjusting the amount of the carrier flowing in the reaction tank.   The carrier amount adjusting means includes a carrier extracting means for extracting a part of the carrier from the reaction tank, a carrier storing means for storing the carrier extracted by the carrier extracting means, and a carrier stored in the carrier storing means. The water treatment apparatus according to claim 4, wherein the water treatment apparatus is configured by a carrier charging unit that charges the reaction tank.   A monitoring means for monitoring the quality of the treated water flowing into the reaction tank and / or the treated water discharged from the reaction tank is provided, and the carrier amount adjusting means is controlled based on the monitoring result by the monitoring means. The water treatment device according to claim 4 or 5, characterized in that.

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