JP6532723B2 - Method and system for treating organic wastewater - Google Patents

Description

  The present invention relates to a method and system for treating organic wastewater in which biological wastewater is treated while circulating organic wastewater between an anoxic tank in which activated sludge is stored and an aerobic tank.

  Patent Document 1 discloses a waste water treatment method employing a circulating nitrification denitrification method. In the circulating nitrification denitrification method, waste water is allowed to flow into the denitrification tank and the nitrification tank in order, part of the nitrification treated water flowing out from the nitrification tank is circulated back to the denitrification tank as the nitrification circulating fluid, and the rest is discharged to the final sedimentation tank It is a biological treatment method, and is a biological treatment method in which nitrogen is removed from sewage by performing nitrification and denitrification with floating activated sludge. In the denitrification tank, BOD components and nitrogen are removed by denitrification reaction, and in the nitrification tank, ammoniacal nitrogen is nitrated to nitric acid or nitrous acid. The denitrification tank is also referred to as an anoxic tank, and the nitrification tank is also referred to as an aerobic tank.

  In the said waste water treatment method, in order to miniaturize an installation, in addition to the floating activated sludge, the nitrifying bacteria immobilization carrier is put into the nitrification tank. Sewage which has flowed into denitrification tank containing floating activated sludge flows from the opening formed in the lower part of tank wall to nitrification tank, and the air is supplied from the aeration device, and the air is supplied to the air. Processing is performed.

  A part of the sewage treated aerobically in the nitrification tank is pumped up by an air lift pump and returned to the denitrification tank via the circulation path, and the nitric acid is reduced to nitrogen and removed in the denitrification tank.

  In Patent Document 2, the DO of the membrane separation tank is maintained at an appropriate value, the generation of the causative agent of the membrane fouling is suppressed, and furthermore, the denitrification reaction in the anoxic tank is maintained in a good state. A sewage treatment method is disclosed that employs a membrane separation activated sludge method.

  In the said waste water treatment method, to-be-processed water is processed aerobically with microorganisms by an aerobic tank provided with an aeration apparatus, to-be-processed water is solid-liquid separation with a membrane separation apparatus by the membrane separation tank arrange | positioned at the back | latter stage of an aerobic tank. Treated water in the membrane separation tank to be circulated to the aerobic tank via the first circulation path, and measure the dissolved oxygen concentration etc. which is an indicator of the aerobic treatment in the membrane separation tank , And the amount of circulation of the circulation path is adjusted based on the measured value. Furthermore, an anoxic tank is installed on the upstream side of the aerobic tank, and the water to be treated in the membrane separation tank is circulated to the anoxic tank via the second circulation path to be denitrified. .

JP-A-11-47786 JP, 2010-194481, A

  In the conventional circulating nitrification denitrification method including the membrane separation activated sludge method described above, in order to stabilize the treatment, a certain amount of waste water treated in the aerobic tank is returned to the anoxic tank through the circulation path It was configured to be. And, in order to supply the sewage to the circulation path, it was equipped with a dedicated pump such as an air lift pump or a mechanical pump.

  When an air lift pump is used, a dedicated blower is often provided separately from the blower for supplying air to the aeration apparatus installed in the aerobic tank.

  However, when nitrogen load such as ammonia nitrogen contained in organic wastewater treated by membrane separation activated sludge method fluctuates significantly, especially when nitrogen load increases, the amount of circulating organic wastewater is kept constant. If this is done, there is a disadvantage that the nitrogen concentration of the treated water will eventually increase.

  Then, although it is possible to adjust the amount of circulation return of organic drainage variably according to the grade of nitrogen load, there existed a problem that equipment cost will increase, if an adjustment mechanism for exclusive use is provided.

  SUMMARY OF THE INVENTION In view of the problems described above, the object of the present invention is to adjust the amount of circulating organic waste water from an aerobic tank to an anoxic tank appropriately according to fluctuations in nitrogen load without causing an increase in equipment cost. It is in the point of providing the disposal method of organic drainage, and its disposal system.

In order to achieve the above-mentioned object, the first characterizing feature of the method for treating organic wastewater according to the present invention is, as described in claim 1 of the document of the claims, that organic sludge is not stored with activated sludge. It is a processing method of the organic drainage which carries out a biological treatment, making it circulate between an oxygen tank and an aerobic tank, wherein the aerobic tank is provided with an auxiliary aeration area where an aerator is arranged, and a membrane separation device. It is configured to include a membrane separation zone, the order to transfer the activated sludge from the aerobic tank following the air charge of increase and decrease to the aeration device for aerobic treatment in the aerobic tank to the anoxic tank In order to increase or decrease the amount of air supplied to the air lift pump, air is supplied to the aeration apparatus and the air lift pump with a common blower, and the amount of air supplied from the blower is increased or decreased based on the properties of activated sludge. adjusting, by the air lift pump Certain activated sludge Kimaku separation zone to the point of transfer to the anoxic tank.

Since the air is supplied to the aeration apparatus and the air lift pump through the common blower, if the property of activated sludge is in a state of high nitrogen load, the amount of air supplied from the blower will be increased and adjusted. As the amount of air supplied to the aeration apparatus increases, the amount of dissolved oxygen in the aerobic tank increases, the nitrification treatment is promoted, and the activated sludge transferred from the aerobic tank to the anoxic tank is appropriately increased accordingly The denitrification treatment is promoted by this. On the contrary, if the property of activated sludge is in a state of low nitrogen load, the amount of air supplied from the blower is decreased and adjusted, the amount of air supplied to the aeration device is decreased, and the amount of dissolved oxygen in the aerobic tank is suppressed. As a result, the amount of activated sludge transferred from the aerobic tank to the anoxic tank is appropriately reduced, and the circulation of unnecessary activated sludge is suppressed. Therefore, without and supplies excess oxygen or cause an increase in equipment cost to the anoxic tank, ing to allow flexibility denitrified in response to variations in the nitrogen load.

Then, it is properly nitrified auxiliary aeration zone in accordance with a variation in nitrogen load, since membrane separated organic waste water after the membrane separation zone is transferred together with the activated sludge to the anoxic tank, the activated sludge nitrogen Even if the load is high, efficient denitrification treatment will be promoted in the anoxic tank.

According to the second characteristic configuration, as described in the second aspect, in addition to the above-mentioned first characteristic configuration, the property of the activated sludge serving as the indicator is the concentration of dissolved oxygen, the redox potential, the total nitrogen concentration, It is a point represented by either ammonia nitrogen concentration or nitrate nitrogen concentration.

  As the properties of activated sludge, dissolved oxygen concentration (hereinafter also referred to as "DO: Dissolved Oxygen"), oxidation reduction potential (hereinafter referred to as "ORP: oxidation-reduction potential"), total nitrogen concentration, ammonia nitrogen concentration By using any of the nitrate nitrogen concentration as an index, it is possible to appropriately grasp the degree of nitrogen load of organic drainage, that is, the degree of nitrification of ammonia nitrogen by microorganisms.

  For example, when the dissolved oxygen concentration DO is lower than the normal value, a large amount of oxygen is consumed in the nitrification of ammonia nitrogen and the nitrogen load is high, and it can be determined that the amount of air supplied to the aerator needs to be increased. . The same applies to total nitrogen concentration, ammonia nitrogen concentration, and nitrate nitrogen concentration. On the other hand, if the ORP in the activated sludge of the anoxic tank is higher than the normal value, it can be determined that the nitrogen load where oxygen is not consumed is in a low state, and it is determined that the amount of air supplied to the aeration device needs to be reduced. it can.

The first characterizing feature of the processing system of organic waste water according to the invention the biological treatment while circulating between the plurality of biological treatment tank through, the organic waste water is activated sludge stored as described in the claim 3 An organic waste water treatment system comprising: an anoxic tank; an aerobic tank; a transfer path for transferring activated sludge from the anoxic tank to the aerobic tank; and activity from the aerobic tank to the anoxic tank An air lift pump for transferring sludge, an aeration apparatus disposed in the aerobic tank, a common blower capable of variably adjusting the amount of air supplied to the air lift pump and the aeration apparatus, and properties of activated sludge are measured. And a control means for increasing or decreasing the amount of air supplied from the blower based on the measured value from the sludge property measuring means, and the aerobic tank is provided with the aeration device. Auxiliary aeration area and membrane separation Location is configured with the placed membrane separation zone, the supply of following the air charge of increase and decrease to the aeration device based on the control of the air supply amount from the blower by the control unit to the air-lift pump The amount is also increased or decreased, and the air lift pump is configured to transfer the activated sludge in the membrane separation area to the anoxic tank .

  As described above, according to the present invention, it is possible to properly adjust the amount of circulating organic waste water from the aerobic tank to the anoxic tank according to the fluctuation of the nitrogen load without increasing the facility cost. It has become possible to provide a method for treating wastewater and its treatment system.

The explanatory view of the processing system of the organic drainage by the present invention (A) is a control characteristic diagram of the auxiliary aeration air volume according to the change of the total nitrogen concentration of the organic waste water, (b) is a correlation characteristic diagram of the auxiliary aeration air volume and the air lift air volume, (c) is the air lift air volume and sludge circulation volume Correlation characteristic chart Explanatory drawing of the organic waste water treatment system which shows another embodiment Explanatory drawing of the organic waste water treatment system which shows another embodiment Explanatory drawing of the organic waste water treatment system which shows another embodiment

  Hereinafter, embodiments of the method for treating organic wastewater and the treatment system according to the present invention will be described.

  As shown in FIG. 1, the organic waste water treatment system 1 is a system for biological treatment while circulating organic waste water mixed with activated sludge among a plurality of biological treatment tanks, and activated sludge is stored. Anoxic tank 2 and aerobic tank 3, a transfer path 4 for transferring activated sludge from the anoxic tank 2 to the aerobic tank 3, and an air lift pump for transferring activated sludge from the aerobic tank 3 to the anoxic tank 2 It is equipped with five.

  The aerobic tank 3 includes an auxiliary aeration area 3A in which the aeration apparatus 6 is disposed, and a membrane separation area 3B in which the membrane separation apparatus 7 is disposed. There is no activated sludge in the membrane separation area 3B by the air lift pump 5 It is configured to be transferred to the oxygen tank 2.

  Furthermore, to the measurement values from the common property blower 8 capable of variably adjusting the amount of air supplied to the air lift pump 5 and the aeration device 6, the sludge property measuring means 10 for measuring the property of activated sludge, and the sludge property measuring means 10 Control means 11 is provided to increase or decrease the amount of air supplied from the blower 8 based on the control means 11.

  The air lift pump 5 is configured to include a transfer pipe 5c in a substantially horizontal posture with a diffuser pipe 5a and a pumping pipe 5b, and configured so that activated sludge in the membrane separation area 3B is returned to the upstream side of the anoxic tank 2 .

  The organic waste water flowing into the drainage inflow part 2a of the anoxic tank 2 was provided on the partition wall between the anoxic tank 2 and the aerobic tank 3 after a part of the organic component was treated by microorganisms under anoxic conditions. Ammonia nitrogen is nitrified to nitrate nitrogen under aerobic conditions which overflows into the aerobic tank 3 and overflows into the aerobic tank 3 and is aerated in the auxiliary aeration zone 3A of the aerobic tank 3 and is further provided in the membrane separation zone 3B. Membrane-permeated water purified by being permeated by the membrane separator 7 is obtained.

  The activated sludge that has flowed down to the membrane separation zone 3B is returned to the upstream side of the anoxic tank 2 by the air lift pump 5, and is denitrified by reducing nitrate nitrogen in the anoxic tank 2 under anoxic conditions. Nitrogen gas is separated and removed.

  Sewage, septic tank sludge, human waste, waste water generated in food processing plant etc. are targeted for organic waste water to be purified by the organic waste water treatment system 1, and especially organic waste water containing nitrogen components such as ammonia etc. It becomes suitable treatment target water.

  The aeration device 6 includes an aeration unit 6a in which a plurality of small-diameter injection holes are formed, an air supply pipe 6b for supplying air to the aeration unit 6a, and a blower 8 for injecting air to the air supply pipe 6b. By adjusting the rotational speed of the blower 8, the air supply amount is adjusted to be increased or decreased. As the control means 11, a personal computer or a microcomputer is suitably used.

  The control means 11 is connected to a signal line from the sludge property measuring means 10 for measuring the property of the activated sludge, and the rotational speed of the blower 8 is controlled by using the property of the activated sludge inputted through the signal line as an index. . For example, when an induction motor is used as a drive source of the blower 8, the number of rotations of the induction motor is controlled via an inverter circuit connected to the control means 11.

  A dissolved oxygen concentration meter 10 a is installed in the aerobic tank 3 as the sludge property measuring means 10. The control means 11 determines that the nitrogen load of the organic drainage is rising when the DO measured by the dissolved oxygen concentration meter 10a falls below a preset target value, and the blower 8 makes the DO become the target value. Control the rotation speed of the blower 8 so that the nitrogen load of the organic drainage drops when the DO rises above the preset target value and the DO becomes the target value Do.

  As sludge property measurement means 10 to monitor the state of nitrogen load of organic waste water, in addition to dissolved oxygen concentration meter 10a, a redox potential sensor, total nitrogen concentration meter, ammonia nitrogen concentration meter (ammonia concentration meter), nitrate nitrogen concentration A meter etc. can be used.

  For example, when the DO of the aerobic tank is low, it can be determined that the values of the total nitrogen concentration meter, ammonia concentration meter, and nitrate nitrogen concentration meter are both high, and the nitrogen load is high. It can be determined that the amount needs to be increased, and when the ORP of the anoxic tank is high, it can be determined that the nitrogen load is low, and it can be determined that the air supply amount needs to be reduced.

  The dissolved oxygen concentration meter, the total nitrogen concentration meter, the ammonia concentration meter, and the nitrate nitrogen concentration meter are mainly installed in the aerobic tank 3 or the treated water tank, and the redox potential sensor is mainly installed in the anoxic tank 2.

  To the air supply pipe 6b connected to the blower 8, a branch pipe 5d for supplying air for air diffusion to the air diffusion pipe 5a of the air lift pump 5 is branch-connected. When the control means 11 determines that the nitrogen load of the organic waste water has increased using the measurement value of the sludge property measurement means 10 as an index, and increases the amount of air supplied from the blower 8, the amount of air supplied to the aeration device 6 The amount of air supplied to the air lift pump 5 is increased following the increase.

  As a result, the nitrification process for ammonia nitrogen in the aerobic tank 3 is promoted to increase nitrate nitrogen, and at the same time the amount of activated sludge containing nitrate nitrogen is returned to the anoxic tank 2, the nitrogen removal rate is increased. Is enhanced.

  In addition, since the amount of air supplied to the aeration device provided at the lower part of the membrane separation device 7 needs to be adjusted independently regardless of the fluctuation of nitrogen load of activated sludge, the blower connected to the aeration device is independently It is provided.

  If the control means 11 determines that the nitrogen load of the organic waste water has decreased using the measured value by the sludge property measurement means 10 as an index, and controls to decrease the amount of air supplied from the blower 8, the amount of air supplied to the aerator 6 Following the decrease, the amount of air supplied to the air lift pump 5 is reduced.

  As a result, excessive air supply unnecessary for the nitrification treatment of ammonia nitrogen in the aerobic tank 3 is suppressed.

  The test data of the treatment system 1 of the organic waste water demonstrated in FIG. 1 are shown by FIG. 2 (a), (b), (c). As shown in FIG. 2 (a), when the total nitrogen concentration of raw water which is organic drainage fluctuates with time and decreases, the auxiliary aeration air volume and the air lift air volume are controlled to decrease, and when it increases, the auxiliary aeration air volume and the air lift air volume The control characteristics to be incrementally controlled are shown. At this time, Fig. 2 (b) shows how the air lift air volume increases following the increase of the auxiliary aeration air volume, and Fig. 2 (c) shows how the sludge circulation volume increases when the air lift air volume increases. ing.

  That is, the amount of air supplied from the blower 8 is increased or decreased by using the property of activated sludge as an index by the control means 11 of the organic waste water treatment system 1 described above, and the amount of sludge circulation by the air lift pump 5 follows A controlled method of control is realized.

Another embodiment will be described below.
Although the previous embodiment described the configuration in which the auxiliary aeration area 3A and the membrane separation area 3B are disposed adjacent to each other without being divided into the aerobic tank 3, the auxiliary aeration area 3A and the membrane separation area 3B are partition walls. Etc. may be configured to be clearly divided.

  In the embodiment described above, the amount of air supplied to the aeration device 6 is increased or decreased by adjusting the rotational speed of the blower 8, and the amount of air supplied to the air lift pump 5 is increased or decreased to follow it. However, as shown in FIG. 3, a valve V is provided between the blower and the air supply pipe 6b and the branch pipe 5d to maintain the rotational speed of the blower 8 constant while using the property of activated sludge as an index. You may adjust the opening degree of.

  In the previous embodiment, an example was described in which the aerobic tank 3 was configured to include the auxiliary aeration area 3A in which the aeration device 6 is disposed, and the membrane separation area 3B in which the membrane separation device 7 is disposed. As shown in FIG. 4, the present invention can be applied to an example where the mechanical tank 3 is not provided with the membrane separation area 3B and only the auxiliary aeration area 3A is provided.

  Although the biological treatment tank which comprises the processing system 1 of organic drainage explained the example by which only the anoxic tank 2 and the aerobic tank 3 were comprised in previous embodiment, you may further provide the anaerobic tank 9 . As shown in FIG. 5, for example, an anaerobic tank 9 may be provided at the front stage of the anoxic tank 2, and phosphorus taken into activated sludge in the aerobic tank 3 may be released in the anaerobic tank. In this case, by providing a return path for returning the activated sludge in the anoxic tank 2 to the anaerobic tank 9, the phosphorus taken in the aerobic tank 3 is denitrified in the anoxic tank 2 and then released in the anaerobic tank 9. Become so.

  In the embodiment described above, an aspect has been described in which the air supply pipe 6b for supplying air to the aeration device 6 and the branch pipe 5d for supplying air to the air lift pump 5 are not provided with flow rate adjusting means such as a valve. A valve or the like may be provided on at least one of the branch pipes 5d. In this case, if the amount of air supplied to the aeration device 6 and the air lift pump 5 is adjusted to a predetermined ratio by the valve or the like, the aeration device is adjusted according to the increase or decrease of the amount of air supplied from the common blower 8 thereafter. The amounts of air supplied to the air lift pump 5 and the air lift pump 5 are increased or decreased while maintaining the predetermined ratio.

  The embodiments described above are all examples of the present invention, and the present invention is not limited by the description, and the specific configuration of each part can be appropriately modified and designed within the range where the effects of the present invention can be exhibited. It goes without saying that In addition, any one or more of the plurality of embodiments described above may be combined as appropriate.

1: Organic waste water treatment system 2: Anoxic tank 3: Aerobic tank 4: Transfer route 5: Air lift pump 5a: Diffuser 5b: Pumping pipe 5c: Transfer pipe 5d: Branch pipe 6: Aeration device 6a: Aeration part 6b: air supply pipe 8: blower 10: sludge property measuring means 11: control means

Claims (3)

A method of treating organic wastewater, wherein the organic wastewater is subjected to biological treatment while being circulated between an anoxic tank where activated sludge is stored and an aerobic tank,
The aerobic tank is configured to include an auxiliary aeration area in which the aeration apparatus is disposed, and a membrane separation area in which the membrane separation apparatus is disposed;
The air charge to the air lift pump for transferring the activated sludge to the anoxic tank to follow the air charge of increasing or decreasing from the aerobic tank to the aeration device for aerobic treatment in the aerobic tank is Supplying air to the aeration apparatus and the air lift pump with a common blower so as to increase or decrease;
Treatment of organic wastewater characterized in that the amount of air supplied from the blower is increased or decreased by using the property of activated sludge as an index, and the activated sludge in the membrane separation area is transferred to the anoxic tank by the air lift pump Method. Properties of activated sludge to be the index, dissolved oxygen concentration, redox potential, total nitrogen concentration, ammonia nitrogen concentration, organic according to claim 1, characterized by being represented by any one of nitrate nitrogen concentration Wastewater treatment method. What is claimed is: 1. A system for treating organic wastewater, which bioprocesses organic wastewater while circulating the organic wastewater among a plurality of biological treatment tanks in which activated sludge is stored,
An anoxic tank, an aerobic tank, a transfer path for transferring activated sludge from the anoxic tank to the aerobic tank, an air lift pump for transferring activated sludge from the aerobic tank to the anoxic tank, An aeration apparatus disposed in an air tank, a common blower capable of variably adjusting the amount of air supplied to the air lift pump and the aeration apparatus, sludge property measurement means for measuring properties of activated sludge, and the sludge property measurement Control means for increasing or decreasing the amount of air supplied from the blower based on the measurement value from the means;
The aerobic tank comprises an auxiliary aeration area in which the aeration apparatus is disposed, and a membrane separation area in which the membrane separation apparatus is disposed;
Air supply amount to the air lift pump to follow the air charge of increase and decrease to the aeration device based on the control of the air supply amount from the blower by the control means is also increased or decreased, the membrane separation zone by the air lift pump A system for treating organic wastewater, which is configured to transfer activated sludge to the anoxic tank .

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