JP2016193386A - Method for forming aerobic granule, apparatus for forming aerobic granule, wastewater treatment method, and wastewater treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming aerobic granules using a semi-batch reaction vessel which can generate excellent aerobic granules even in wastewater having a high ratio of SS component in the organic substance concentration.SOLUTION: An aerobic granule forming method using a semi-batch reaction vessel 10 generates aerobic granules by repeatedly performing an inflow step of making organic substance-containing wastewater flow in, a biological treatment step of biologically treating objects to be treated in the organic substance-containing wastewater by microbial sludge, a settling step of settling the microbial sludge, and a discharge step of discharging the biologically treated water. The volume load of SS in the organic substance-containing wastewater to the semi-batch reaction vessel 10 is set to 0.6 kgSS/m/d or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an aerobic granule forming method and an aerobic granule forming apparatus for stably forming an aerobic granule in order to aerobically biotreat organic wastewater containing organic matter and the like. Further, the present invention relates to a wastewater treatment method using the formed granules and a wastewater treatment apparatus.

  Conventionally, an activated sludge method utilizing an aggregate of microorganisms (aerobic biological sludge) called floc has been used for biological wastewater treatment of organic matter-containing wastewater containing organic matter and the like. However, in the activated sludge method, when the floc (aerobic biological sludge) and the treated water are separated in the sedimentation basin, the surface area of the sedimentation basin may have to be very large due to the slow sedimentation speed of the floc. The treatment rate of the activated sludge method depends on the sludge concentration in the biological treatment tank, and the treatment rate can be increased by increasing the sludge concentration, but the sludge concentration ranges from 1500 to 5000 mg / L or If it is further increased, solid-liquid separation becomes difficult due to bulking or the like in the sedimentation basin, and the treatment may not be maintained.

  On the other hand, in anaerobic biological treatment, it is common to use aggregates (anaerobic biological sludge) in which microorganisms called granules are densely aggregated and granulated. Granules have a very fast sedimentation rate, and microorganisms gather densely. Therefore, the sludge concentration in the biological treatment tank can be increased, and high-speed wastewater treatment can be realized. However, anaerobic biological treatment has problems such as the fact that the type of wastewater to be treated is limited compared to aerobic treatment (activated sludge method) and that the treated water temperature needs to be maintained at about 30 to 35 ° C. May have. In addition, when the anaerobic biological treatment alone is poor in the quality of the treated water, it may be necessary to separately perform an aerobic treatment such as an activated sludge method when discharged into a river or the like.

  In recent years, treatment is performed using a semi-batch treatment device that intermittently flows wastewater into a reaction tank, and the sedimentation time of biological sludge is shortened, so that it settles not only for anaerobic biological sludge but also for aerobic biological sludge. It has become clear that it is possible to form biological sludge that is granulated with good properties (see, for example, Patent Documents 1 to 4). By granulating the aerobic biological sludge, the average particle size becomes 0.2 mm or more, and the sedimentation speed can be 5 m / h or more. In the semi-batch treatment system, there are four types of treatment: (1) inflow of wastewater, (2) biological treatment of the material to be treated, (3) sedimentation of biological sludge, (4) discharge of treated water. Processing is performed according to the process. By forming granulated aerobic biological sludge with good sedimentation as described above, it is possible to maintain the sludge concentration in the tank at a high concentration, and high-speed treatment becomes possible.

  In the method of forming an aerobic granule using a semi-batch reaction tank, the wastewater to be input has a low BOD concentration (for example, about 80 to 200 mg / L) like sewage and is suspended in the organic matter-containing wastewater. In particular, when the ratio of BOD components derived from SS to the total BOD in the organic matter-containing wastewater is large (for example, 0.4 or more), granulated sludge with high sedimentation is stabilized. It may be difficult to maintain.

International Publication No. 2004/024638 JP 2008-212878 A Japanese Patent No. 4975541 Japanese Patent No. 4804888

  An object of the present invention is a method for forming an aerobic granule using a semi-batch type reaction tank, which is capable of forming a good aerobic granule even in wastewater having a high SS component ratio in the organic matter concentration. An object of the present invention is to provide a method for forming an aerobic granule, a device for forming an aerobic granule, a waste water treatment method using the formed granule, and a waste water treatment device.

The present invention includes an inflow step for flowing in organic matter-containing wastewater containing organic matter, a biological treatment step for biologically treating the target substance in the organic matter-containing wastewater with microbial sludge, and a sedimentation step for sedimenting the microbial sludge. A method for forming an aerobic granule using a semi-batch type reaction vessel that repeats the discharging step of discharging the biologically treated biologically treated water to form granules, the organic matter containing waste water It is the formation method of the aerobic granule which makes the volume load with respect to the said semi-batch type reaction vessel of SS inside 0.6 kgSS / m < ³ > / day or less.

  In the aerobic granule formation method, it is preferable when the ratio of SS-derived BOD to the total BOD concentration of the organic matter-containing wastewater flowing into the semi-batch reaction tank is 0.4 or more.

  In the method for forming an aerobic granule, the biologically treated water discharge port of the semi-batch reaction tank is provided above a drain inlet, and the organic substance-containing waste water is allowed to flow into the semi-batch reaction tank. It is preferable to discharge treated water from the biological treated water discharge port.

The present invention includes an inflow step for flowing in organic matter-containing wastewater containing organic matter, a biological treatment step for biologically treating the target substance in the organic matter-containing wastewater with microbial sludge, and a sedimentation step for sedimenting the microbial sludge. An apparatus for forming an aerobic granule comprising a semi-batch type reaction tank for repeating the discharge step of discharging the biologically treated biologically treated water to form granules, wherein the organic matter-containing wastewater Is an aerobic granule forming apparatus in which the volumetric load on the semi-batch reaction tank is 0.6 kg SS / m ³ / day or less.

  In the aerobic granule forming apparatus, it is preferable when the ratio of SS-derived BOD to the total BOD concentration of waste water flowing into the semi-batch reaction tank is 0.4 or more.

  In the aerobic granule forming apparatus, the biologically treated water discharge port of the semi-batch reaction tank is provided above a waste water inlet, and the organic substance-containing waste water is allowed to flow into the semi-batch reaction tank. It is preferable to discharge treated water from the biological treated water discharge port.

  The present invention supplies the granules formed by the aerobic granule formation method to a continuous biological treatment tank that biologically treats the organic matter-containing wastewater with biological sludge while allowing the organic matter-containing wastewater to flow continuously. Wastewater treatment method.

  The present invention comprises a continuous biological treatment tank for biologically treating the organic matter-containing wastewater with biological sludge while continuously flowing the organic matter-containing wastewater, and the granule formed by the aerobic granule forming apparatus is This is a wastewater treatment device that supplies a continuous biological treatment tank.

  According to the present invention, in the method of forming an aerobic granule using a semi-batch type reaction tank, a favorable aerobic granule can be formed even in wastewater having a high SS component ratio in the organic matter concentration. An aerobic granule formation method, an aerobic granule formation device, a wastewater treatment method using the formed granule, and a wastewater treatment device can be provided.

It is a schematic block diagram which shows an example of the formation apparatus of the aerobic granule which concerns on embodiment of this invention. It is a schematic block diagram which shows the other example of the formation apparatus of the aerobic granule which concerns on embodiment of this invention. It is a schematic block diagram which shows the other example of the formation apparatus of the aerobic granule which concerns on embodiment of this invention. It is a schematic block diagram which shows the other example of the formation apparatus of the aerobic granule which concerns on embodiment of this invention. It is a schematic block diagram which shows an example of the waste water treatment equipment which concerns on embodiment of this invention. It is a figure which shows the daily change of SVI5 in Example 1. FIG. It is a figure which shows the secular change of SVI5 in Example 2. FIG.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

<Aerobic Granule Forming Method and Forming Apparatus>
An example of an aerobic granule forming apparatus according to an embodiment of the present invention is schematically shown in FIG. The granule forming apparatus 1 includes a semi-batch type reaction tank 10. In the granule forming apparatus 1, the drainage supply pipe 22 is connected to the drainage inlet of the semi-batch reaction tank 10 via the drainage inflow pump 12. A biologically treated water pipe 24 is connected to the biologically treated water discharge port 16 of the semi-batch reaction tank 10 via a biologically treated water discharge valve 18. An aeration device 26 connected to the aeration pump 14 is installed in the lower part of the semi-batch reaction tank 10. The drainage inflow pump 12, the biologically treated water discharge valve 18, and the aeration pump 14 may be connected to the control device 20 by electrical connection or the like.

The granule forming apparatus 1 is operated in the following cycle, for example.
(1) Inflow process: The drainage inflow pump 12 is operated, and a predetermined amount of organic matter-containing wastewater flows into the semi-batch reaction tank 10 through the drainage supply pipe 22.

(2) Biological treatment step: The drainage inflow pump 12 is stopped, and an oxygen-containing gas such as air is supplied from the aeration pump 14 to the semi-batch reaction tank 10, and the organic matter-containing wastewater is contained in the semi-batch reaction tank 10. The material to be treated is biologically treated with microbial sludge. The biological reaction is not limited to an aerobic reaction, and supply of air or the like is not performed. An aerobic reaction can be performed by stirring, or an aerobic reaction and an anaerobic reaction may be combined. An oxygen-free state means a state in which dissolved oxygen does not exist, but nitrous acid, oxygen derived from nitric acid, and the like exist. For example, as shown in FIG. 2, a stirring device constituted by a motor 28, a stirring blade 30, a shaft connecting the motor 28 and the stirring blade 30, etc. is installed in the semi-batch reaction tank 10, and the aeration pump 14 is installed. What is necessary is just to stop and to stir with a stirring apparatus. The stirring device is not limited to the above configuration.

(3) Sedimentation step: The aeration pump 14 is stopped, and the sludge in the semi-batch reaction tank 10 is allowed to settle by allowing it to stand for a predetermined time.

(4) Discharge process: By opening the biological treatment water discharge valve 18, the supernatant water obtained in the sedimentation process is discharged from the biological treatment water discharge port 16 through the biological treatment water piping 24 as biological treatment water. In this case, the biologically treated water may be discharged using a pump instead of the biologically treated water discharge valve.

  By repeating the above cycles (1) to (4), granules, which are aggregates in which microorganisms gather densely and become granular, are formed. The operation and stop of the drainage inflow pump 12, the aeration pump 14, and the motor 28 of the stirring device and the opening / closing of the biological treatment water discharge valve 18 may be controlled by the control device 20.

  The granule sludge formed in the semi-batch reaction tank 10 is sludge that has been self-granulated. For example, the average particle diameter of the sludge is 0.2 mm or more, or the sedimentation index SVI5 is 80 mL / g or less biological sludge. Moreover, in this embodiment, whether granule sludge was formed is judged by measuring SVI which is a sedimentation parameter | index of sludge, for example. Specifically, the SVI value is periodically measured by a sludge settling test in the semi-batch reaction tank 10, and the value of SVI5 calculated from the volume ratio after settling for 5 minutes is equal to or less than a predetermined value (for example, 80 mL / g or less), it can be determined that granule sludge has been formed. Alternatively, the particle size distribution of the sludge in the semi-batch reaction tank 10 is measured, and it is determined that the granular sludge has been formed when the average particle size becomes a predetermined value or more (for example, 0.2 mm or more). (The lower the SVI value, the larger the average particle size, the better the granular sludge can be determined).

The present inventors set the volumetric load on the semi-batch reaction tank 10 of SS in the organic substance-containing waste water to 0.6 kgSS / m ³ / day or less, thereby using the semi-batch reaction tank to aerobic granules. It has been found that a favorable aerobic granule can be formed even in wastewater having a high SS component ratio in the organic substance concentration.

On the other hand, it is important for the formation of granules in the semi-batch reaction tank to repeat the organic substance concentration gradient in the reaction tank in one cycle, and the biodegradable organic substance concentration in the reaction tank is high (satisfaction state). It is considered that time (starvation time) in which biodegradable organic substances are almost zero is necessary. In general, SS organic substances such as suspension and colloidal substances are not directly ingested by microorganisms, but are hydrolyzed by extracellular hydrolases produced by microorganisms to become low-molecular-weight organic substances. It is used for metabolism in microbial cells. In other words, the time required to be metabolized by a living organism is longer than the soluble organic matter. SS organic matter that is ingested by microorganisms through hydrolysis is slowly converted into a biodegradable form, so if the volume load of SS organic matter to the semi-batch reactor is high, starvation There is a concern that time will be shortened. Therefore, it is considered that a sufficient starvation time can be provided by setting the volume load of the SS organic material to 0.6 kgSS / m ³ / day or less.

In addition, since the SS-derived BOD inhibits the formation of granules, a method of operating the sludge concentration high to further decompose the SS-derived BOD component can be considered. The decomposition efficiency of organic substances does not change much compared to the case where the sludge concentration is low. Therefore, when having a sludge concentration of a certain level (1000 mg MLSS / L) or more, it is possible to stably form granules by operating at a volume load of SS organic matter of 0.6 kgSS / m ³ / day or less. it is conceivable that.

The volume load of the SS in the organic matter-containing wastewater with respect to the semi-batch reaction tank 10 is 0.6 kgSS / m ³ / day or less, and more preferably 0.3 kgSS / m ³ / day or less. When this volumetric load is larger than 0.6 kgSS / m ³ / day, it is difficult to form good granules.

  When the ratio of SS-derived BOD to the total BOD concentration of the organic matter-containing wastewater flowing into the semi-batch reactor 10 is 0.4 or more, and when it is in the range of 0.4 to 0.8 Is more preferable. When this ratio is greater than 0.8, most of the BOD components are slowly converted into a biodegradable form, making it difficult to form a concentration gradient (concentration difference in the reaction vessel) and forming granules. May be difficult.

  Organic substance-containing wastewater to be treated by the granule forming method according to the present embodiment is organic containing biodegradable organic matter such as food processing factory wastewater, chemical factory wastewater, semiconductor factory wastewater, machine factory wastewater, sewage, and human waste. It is drainage. In addition, when a biologically indegradable organic substance is contained, a physicochemical treatment such as ozone treatment or Fenton treatment is performed in advance and converted into a biodegradable component. Moreover, although the granule formation method according to the present embodiment is intended for various BOD components, the oil and fat content may adhere to sludge and granule sludge, which may have an adverse effect. It is preferable to remove in advance to, for example, about 150 mg / L or less by an existing method such as levitation separation, coagulation pressure levitation, and adsorption.

  The pH in the semi-batch reactor 10 is preferably set in a range suitable for general microorganisms, for example, preferably in the range of 6-9, and in the range of 6.5-7.5. Is more preferable. When the pH value is out of the above range, it is preferable to control the pH by adding acid, alkali or the like.

  The dissolved oxygen (DO) in the semi-batch reaction tank 10 is preferably 0.5 mg / L or more, particularly 1 mg / L or more under aerobic conditions.

In terms of promoting the granulation of biological sludge, the organic matter-containing wastewater in the semi-batch reaction tank 10 or the organic matter-containing wastewater before being introduced into the semi-batch reaction tank 10 is added to Fe ²⁺ , Fe ³⁺ , Ca ²⁺ , It is preferable to add ions that form hydroxides, including Mg ^{2+ and the} like. Normal organic wastewater contains fine particles that become the nucleus of the granule, but the addition of the ions makes it possible to further promote the nucleation of the granule.

  Another example of the aerobic granule forming apparatus according to this embodiment is shown in FIG. In the granule forming apparatus 1 of FIG. 3, the drainage supply pipe 22 is connected to the drainage inlet 34 at the lower part of the semi-batch reaction tank 10 via the drainage inflow pump 12 and the drainage inflow valve 32. A drainage discharge part 36 is connected to the drainage inlet 34 and is installed in the lower part of the semi-batch reaction tank 10. The biologically treated water discharge port 16 of the semi-batch reaction tank 10 is provided above the drainage inlet 34, and the biologically treated water piping 24 is connected to the biologically treated water outlet 16 through the biologically treated water discharge valve 18. Yes. The biologically treated water discharge port 16 is provided above the drainage inlet 34. However, in order to prevent a short circuit of the inflowing organic matter-containing drainage and to form granules more efficiently, the biologically treated water discharge port 16 is separated as much as possible from the drainage inlet 34. It is preferable to be provided at the water level in the sedimentation process. The drainage inflow pump 12, the drainage inflow valve 32, the biologically treated water discharge valve 18, the aeration pump 14, and the motor 28 of the stirring device may be connected to the control device 20 by electrical connection or the like. The other configuration is the same as that of the granule forming apparatus 1 of FIG.

  In the granule forming apparatus 1 of FIG. 3, (4) in the discharging process, the drainage inflow valve 32 is opened to operate the drainage inflow pump 12, and the organic matter-containing drainage is discharged from the drainage inlet 34 through the drainage supply pipe 22. The biologically treated water is discharged from the biologically treated water discharge port 16 through the biologically treated water piping 24 by flowing into the semi-batch type reaction tank 10. The operation and stop of the drainage inflow pump 12, the aeration pump 14, and the agitator motor 28, and the opening and closing of the drainage inflow valve 32 and the biologically treated water discharge valve 18 may be controlled by the control device 20.

  As described above, in the granule forming apparatus 1 shown in FIG. 3, granules are formed by repeating three cycles of (1) inflow process / discharge process, (2) biological treatment process, and (3) sedimentation process. .

  In the granule forming apparatus 1 shown in FIG. 3, the biologically treated water is discharged from the biologically treated water discharge port 16 by causing the organic substance-containing wastewater to flow into the semi-batch type reaction tank 10, so that the granules having a relatively small particle size are formed. Granules can be formed more efficiently by repeating the cycles (1) to (3) for granules discharged with biologically treated water and having a relatively large particle size.

  Another example of the aerobic granule forming apparatus according to this embodiment is shown in FIG. In the granule forming apparatus 1 of FIG. 4, the drainage supply pipe 22 is connected to the drainage inlet 34 at the lower part of the semi-batch reaction tank 10 via the drainage inflow pump 12 and the drainage inflow valve 32. A drainage discharge part 36 is connected to the drainage inlet 34 and is installed in the lower part of the semi-batch reaction tank 10. The biologically treated water discharge port 16 of the semi-batch reaction tank 10 is provided above the drainage inlet 34, and the biologically treated water piping 24 is connected to the biologically treated water outlet 16 through the biologically treated water discharge valve 18. Yes. The biologically treated water discharge port 16 is provided above the drainage inlet 34. However, in order to prevent a short circuit of the inflowing organic matter-containing drainage and to form granules more efficiently, the biologically treated water discharge port 16 is separated as much as possible from the drainage inlet 34. It is preferable to be provided at the water level in the sedimentation process. The drainage inflow pump 12, the drainage inflow valve 32, the biologically treated water discharge valve 18, and the aeration pump 14 may be connected to the control device 20 by electrical connection or the like. The other configuration is the same as that of the granule forming apparatus 1 of FIG.

  In the granule forming apparatus 1 of FIG. 4, in the (4) discharging process, the drainage inflow valve 32 is opened to operate the drainage inflow pump 12, and the organic matter-containing drainage is discharged from the drainage inlet 34 through the drainage supply pipe 22. The biologically treated water is discharged from the biologically treated water discharge port 16 through the biologically treated water piping 24 by flowing into the semi-batch type reaction tank 10. The operation and stop of the drainage inflow pump 12 and the aeration pump 14 and the opening and closing of the drainage inflow valve 32 and the biologically treated water discharge valve 18 may be controlled by the control device 20.

  As described above, in the granule forming apparatus 1 of FIG. 4, the granule is formed by repeating the three cycles of (1) inflow / discharge, (2) biological treatment, and (3) sedimentation. .

  In the granule forming apparatus 1 shown in FIG. 4, the biologically treated water is discharged from the biologically treated water discharge port 16 by causing the organic substance-containing wastewater to flow into the semi-batch type reaction tank 10, so that the granules having a relatively small particle size are formed. Granules can be formed more efficiently by repeating the cycles (1) to (3) for granules discharged with biologically treated water and having a relatively large particle size.

<Wastewater treatment method and wastewater treatment equipment>
The wastewater treatment apparatus according to the present embodiment includes a continuous biological treatment tank that biologically treats organic matter-containing wastewater with biological sludge while allowing organic matter-containing wastewater to flow continuously. In the wastewater treatment method and the wastewater treatment apparatus according to this embodiment, the aerobic granule formation method is applied to a continuous biological treatment tank that biologically treats organic matter-containing wastewater with biological sludge while continuously flowing organic matter-containing wastewater. The granules formed by the above are supplied.

  FIG. 5 shows a schematic configuration of an example of the waste water treatment apparatus according to the present embodiment. The waste water treatment device 3 includes a waste water storage tank 50, a semi-batch reaction tank 10, a continuous biological treatment tank 52, and a solid-liquid separation device 54.

  In the wastewater treatment apparatus 3, the outlet of the wastewater storage tank 50 and the drainage inlet of the continuous biological treatment tank 52 are connected by a drainage supply pipe 66 via a pump 56 and a valve 58. The outlet of the continuous biological treatment tank 52 and the inlet of the solid-liquid separator 54 are connected by a pipe 70. A treated water pipe 72 is connected to the treated water outlet of the solid-liquid separator 54. A sludge discharge pipe 74 is connected to the sludge outlet of the solid-liquid separator 54 via a valve 62, and the upstream side of the valve 62 of the sludge discharge pipe 74 and the return sludge inlet of the continuous biological treatment tank 52 are connected via a pump 64. And connected by a sludge return pipe 76. A drainage supply pipe 22 is connected between the pump 56 and the valve 58 of the drainage supply pipe 66 and the drainage inlet of the semi-batch reaction tank 10 through a drainage inflow valve 32. The biological treatment water discharge port of the semi-batch reaction tank 10 and the biological treatment water inlet of the continuous biological treatment tank 52 are connected by a biological treatment water pipe 24 via the biological treatment water discharge valve 18. The sludge discharge port of the semi-batch reaction tank 10 and the sludge inlet of the continuous biological treatment tank 52 are connected by a sludge pipe 68 via a pump 60.

  The continuous biological treatment tank 52 includes, for example, a stirring device, an aeration pump, an aeration device connected to the aeration pump, and the like, and the liquid in the tank is stirred by the stirring device and supplied from the aeration pump. An oxygen-containing gas such as air is configured to be supplied into the tank through the aeration apparatus.

  The solid-liquid separation device 54 is a separation device for separating biological sludge from treated water containing biological sludge and treated water, and examples include separation devices such as sedimentation separation, pressurized flotation, filtration, and membrane separation. .

  In the wastewater treatment apparatus 3, first, the valve 58 is opened, the pump 56 is operated, and the organic matter-containing wastewater in the wastewater storage tank 50 is supplied to the continuous biological treatment tank 52 through the wastewater supply pipe 66. In the continuous biological treatment tank 52, biological treatment of wastewater by biological sludge is performed under aerobic conditions (continuous biological treatment step). The treated water treated in the continuous biological treatment tank 52 is supplied from the outlet of the continuous biological treatment tank 52 to the solid-liquid separator 54 through the pipe 70. In the solid-liquid separator 54, biological sludge is separated from the treated water (solid-liquid separation step). The treated water that has undergone the solid-liquid separation treatment is discharged out of the system through the treated water pipe 72 from the treated water outlet of the solid-liquid separator 54. The biological sludge separated into solid and liquid is discharged to the outside through the sludge discharge pipe 74 by opening the valve 62. The pump 64 may be operated, and at least a part of the biological sludge separated into solid and liquid may be returned to the continuous biological treatment tank 52 through the sludge return pipe 76.

  When operating the semi-batch reaction tank 10, the drainage inflow valve 32 is opened, and at least a part of the organic matter-containing wastewater in the drainage storage tank 50 is supplied to the semi-batch reaction tank 10 through the drainage supply pipe 22. In the semi-batch type reaction vessel 10, the cycle of (1) inflow process, (2) biological treatment process, (3) sedimentation process, (4) discharge process (or (1) inflow process / discharge process, (2) By repeating the biological treatment process (3) the sedimentation process cycle), granules are formed, the pump 60 is operated, and the formed granules are supplied to the continuous biological treatment tank 52 through the sludge pipe 68. .

  In the continuous biological treatment tank 52 shown in FIG. 5, the embodiment in which the biological treatment is performed by the standard activated sludge method for treating organic matter or the like is described as an example, but the present invention is not limited to this. -Nutrient removal systems (systems with anaerobic and anaerobic tanks) such as Anoxic-Oxic Process (AO) and Anaerobic-Oxic Process), oxidation ditch method, step inflow type multi-stage activated sludge method, etc. It may be an apparatus that performs biological treatment by the system. Moreover, the apparatus which performs biological treatment in presence of carriers, such as a polyurethane, a plastics, resin, may be sufficient.

  It is preferable that the continuous biological treatment tank 52 is operated, for example, in a range where the sludge concentration in the tank is 2000 to 20000 mg / L. In order to maintain the soundness (sedimentation, activity, etc.) of biological sludge, the sludge load is preferably in the range of 0.05 to 0.6 kg BOD / MLSS / day, and 0.1 to 0.5 kg BOD. More preferably, the range is / MLSS / day.

  The pH in the continuous biological treatment tank 52 is preferably adjusted to a range of 6 to 9 suitable for general biological treatment, and more preferably adjusted to a range of 6.5 to 7.5. The dissolved oxygen (DO) in the continuous biological treatment tank 52 is preferably 0.5 mg / L or more, more preferably 1 mg / L or more, which is suitable for general biological treatment.

  In the waste water treatment apparatus 3 illustrated in FIG. 5, the configuration including the solid-liquid separation device 54 has been described as an example, but the solid-liquid separation device 54 is not necessarily provided. However, the wastewater treatment device 3 circulates granules to improve the wastewater treatment efficiency, and so on, so that the solid-liquid separation device 54 separates biological sludge from the treated water discharged from the continuous biological treatment tank 52. And it is preferable to provide the sludge return piping 76 which returns the biological sludge discharged | emitted from the solid-liquid separator 54 to the continuous-type biological treatment tank 52. FIG.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

  The following tests were conducted using a semi-batch type reaction tank having a reaction tank effective volume of 4 L (length 140 mm × width 70 mm × height 410 mm). In the semi-batch type reaction tank, the biological treatment water discharge port was installed at the water surface position in the sedimentation process. Sewage was used for the water flow test. The SS concentration of sewage used for water flow is 40 to 170 mg / L, the BOD concentration is 70 to 180 mg / L, and the ratio of the SS-derived BOD concentration to the total BOD concentration is 0.4 to 0.8. there were. The ratio of BOD derived from SS to the total BOD concentration is determined by measuring the total BOD concentration of waste water according to JIS K 0102 21 and filtering the filtrate after filtering with filter paper (No. 5C, JIS P 3801). The BOD concentration (dissolved BOD concentration) was measured, and the BOD concentration derived from SS was calculated from the total BOD concentration minus the BOD concentration of the filtrate.

[Example 1, Example 2, Comparative Example 1, Example 3]
The operation cycle of the semi-batch reactor was performed as follows.
(1) Inflow / discharge process: Wastewater is allowed to flow into the semi-batch reaction tank over 12 minutes, and biologically treated water is discharged from the biologically treated water discharge port (installed with a motorized valve that opens simultaneously with the start of the inflow of wastewater). (See FIG. 4).
(2) Biological treatment process: At the same time as stopping the inflow of wastewater, the biological treatment water discharge valve was closed, and air was supplied from the aeration apparatus installed at the bottom of the reaction tank.
(3) Sedimentation step: The supply of air from the aeration apparatus was stopped and allowed to stand for 10 minutes to settle the sludge in the reaction tank.
The above operations (1) to (3) were repeated.

In both Examples and Comparative Examples, granule formation was evaluated by SVI5 measurement of biological sludge in a semi-batch type reaction tank. The results are shown in FIG. In addition, SVI5 is a sedimentation parameter | index of biological sludge, and is calculated | required with the following method. First, 1 L of sludge is put into a 1 L graduated cylinder, and after gently stirring so that the sludge concentration is as uniform as possible, the sludge interface when allowed to stand for 5 minutes is measured. Then, the volume ratio (%) of sludge in the measuring cylinder is calculated. Next, MLSS (mg / L) of sludge is measured. By applying these to the following equation, SVI5 is calculated. The smaller the SVI5 value, the higher the sedimentation rate of the sludge. When SVI5 was 100 mL / g or less, it was judged as a granule having good sedimentation properties.
SVI5 (mL / g) = volume ratio occupied by sludge × 10,000 / MLSS

  In addition, the volume load of SS shown below was adjusted by the setting of reaction time length according to SS density | concentration of the waste water to be used.

<Example 1>
When water was passed at a volume load of SS of 0.42 kg SS / m ³ / day from the start of water passage to the 28th day, the initial SVI5 decreased from 178 mL / g to 90 mL / g.

<Example 2>
When the volume load of SS was increased from the 29th day of water flow to 0.54 kgSS / m ³ / day, SVI5 was maintained at 80 to 105 mL / g.

<Comparative Example 1>
When the volume load of SS was increased from the 45th day of water flow to 0.65 kgSS / m ³ / day, the value of SVI5 started to increase, and on the 75th day, it became 160 mL / g.

<Example 3>
When the volume load of SS was lowered from the 76th day of water flow to 0.35 kgSS / m ³ / day, the value of SVI5 started to fall, and on the 98th day, it dropped to 57 mL / g.

[Example 4, Example 5]
(4) Inflow / discharge process: The wastewater is allowed to flow into the semi-batch reaction tank over 12 minutes, and the biologically treated water is discharged from the biologically treated water discharge port (installed with an electric valve that opens at the same time as the inflow of the wastewater is installed). I let you.
(5) Biological treatment step: At the same time as stopping the inflow of wastewater, the biological treated water discharge valve was closed, and air was supplied from the air diffuser installed at the bottom of the reaction tank.
(6) Sedimentation step: The supply of air from the aeration apparatus was stopped and allowed to stand for 10 minutes to sediment the sludge in the reaction tank.
The steps (4) to (6) were repeated. The results are shown in FIG.

<Example 4>
When water was passed from the start of water flow to the 75th day so that the volume load of the SS was 0.35 kgSS / m ³ / day, the initial SVI5 started to decrease from 178 mL / g, and on the 26th day, 90 mL / g, and then maintained at 80 to 90 mL / g.

<Example 5>
From the 76th day, when the volumetric load of SS was reduced to 0.3 kgSS / m ³ / day, the value of SVI5 started to decrease further, and on the 99th day, the granule having a very high sedimentation property of 47 mL / g. Could get.

From the above, the BOD concentration of the wastewater is as low as 70 to 180 mg / L by passing the volume load of the SS in the organic matter-containing wastewater to the semi-batch type reaction tank as 0.6 kgSS / m ³ / day or less. Even when the ratio of the BOD concentration derived from SS to the BOD concentration is 0.4 or more, it is possible to form a favorable aerobic granule, and by setting it to 0.3 kgSS / m ³ / day or less. It has been shown that better granules can be formed.

  DESCRIPTION OF SYMBOLS 1 Granule formation apparatus, 3 Waste water treatment apparatus, 10 Semi-batch type reaction tank, 12 Waste water inflow pump, 14 Aeration pump, 16 Biological treatment water discharge port, 18 Biological treatment water discharge valve, 20 Control apparatus, 22, 66 Waste water Supply piping, 24 Biological treatment water piping, 26 Aeration equipment, 28 Motor, 30 Stirring blade, 32 Wastewater inflow valve, 34 Wastewater inlet, 36 Wastewater discharge part, 50 Wastewater storage tank, 52 Continuous biological treatment tank, 54 Solid liquid Separator, 56, 60, 64 pump, 58, 62 valve, 68 sludge piping, 70 piping, 72 treated water piping, 74 sludge discharge piping, 76 sludge return piping.

Claims (8)

An inflow process for introducing an organic matter-containing wastewater containing organic matter, a biological treatment process for biologically treating a target substance in the organic matter-containing wastewater with microbial sludge, a sedimentation process for sedimenting the microbial sludge, and the biology A method of forming an aerobic granule using a semi-batch reaction tank in which granules are formed by repeatedly performing a discharge step of discharging biologically treated water that has been treated automatically,
A method for forming an aerobic granule, wherein a volume load of SS in the organic substance-containing wastewater to the semi-batch reaction tank is 0.6 kgSS / m ³ / day or less. A method for forming an aerobic granule according to claim 1,
The method for forming an aerobic granule, wherein the ratio of SS-derived BOD to the total BOD concentration of organic matter-containing wastewater flowing into the semi-batch reaction tank is 0.4 or more. A method for forming an aerobic granule according to claim 1 or 2,
The biologically treated water discharge port of the semi-batch reaction tank is provided above the drainage inlet, and the biologically treated water is discharged from the biologically treated water discharge port by flowing the organic matter-containing wastewater into the semi-batch type reaction tank. A method for forming an aerobic granule characterized by discharging. An inflow process for introducing an organic matter-containing wastewater containing organic matter, a biological treatment process for biologically treating a target substance in the organic matter-containing wastewater with microbial sludge, a sedimentation process for sedimenting the microbial sludge, and the biology An aerobic granule forming apparatus comprising a semi-batch type reaction tank that repeatedly performs a discharging step of discharging biologically treated water that has been treated automatically to form granules,
An apparatus for forming an aerobic granule, wherein a volume load of SS in the organic matter-containing wastewater to the semi-batch reactor is 0.6 kgSS / m ³ / day or less. An apparatus for forming an aerobic granule according to claim 4,
An apparatus for forming an aerobic granule, wherein the ratio of SS-derived BOD to the total BOD concentration of organic matter-containing wastewater flowing into the semi-batch reaction tank is 0.4 or more. An apparatus for forming an aerobic granule according to claim 4 or 5,
The biologically treated water discharge port of the semi-batch reaction tank is provided above the drainage inlet, and the biologically treated water is discharged from the biologically treated water discharge port by flowing the organic matter-containing wastewater into the semi-batch type reaction tank. An aerobic granule forming apparatus characterized by discharging.   The aerobic granule formation method according to any one of claims 1 to 3, wherein the organic matter-containing wastewater is continuously flowed into a continuous biological treatment tank that biologically treats the organic matter-containing wastewater with biological sludge. A wastewater treatment method, characterized by supplying formed granules.   An apparatus for forming an aerobic granule according to any one of claims 4 to 6, further comprising a continuous biological treatment tank for biologically treating the organic matter-containing wastewater with biological sludge while causing the organic matter-containing wastewater to flow continuously. A wastewater treatment apparatus, characterized in that the granules formed by the above are supplied to the continuous biological treatment tank.

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