JP2011206771A - Granular microbial sludge generation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a granular microbial sludge generation method which can generate granular microbial sludge more quickly.SOLUTION: The granular microbial sludge generation method includes: an inflow step for making organic wastewater flow into an aeration tank 21 containing microbial sludge G1; an inflow step for making organic wastewater flow into the aeration tank 21 containing microbial sludge; a treatment step for subjecting the organic wastewater to aerobic treatment by aeration in the aeration tank 21; an injection step for injecting flocculant into the treatment water treated at the treatment step and discharged from the aeration tank 21 as a granular promoting agent for promoting granulation of the microbial sludge; a separation step for separating solid matter including the microbial sludge from the treatment water treated at the treatment step and containing flocculant in a solid-liquid separation tank 25; and a return step for returning the solid matter separated at the separation step to the aeration tank 21. The adding amount is 10 to 500 mg/l when the flocculant is an inorganic flocculant, and the adding amount is 0.1 to 10 mg/l when the flocculant is a polymeric flocculant.

Description

  The present invention relates to a method for producing granular microbial sludge from aerobic microbial sludge.

  An activated sludge method is known as a biological treatment method for treating organic wastewater. In the activated sludge method, organic wastewater is introduced into an aeration tank using microbial sludge, which is an aerobic activated sludge, and the organic matter in the organic wastewater is decomposed. Therefore, the treatment performance depends on the amount of microbial sludge present in the aeration tank. In order to maintain the amount of microbial sludge in the aeration tank, conventionally, a sedimentation basin is provided after the aeration tank. Yes.

  However, since the sedimentation rate of microbial sludge is small, there is a problem that a large sedimentation basin is required and the construction cost of the equipment becomes high.

  One method for solving such a problem is to use microbial sludge in a granular form for use in wastewater treatment. Until now, it was thought that it was difficult to form granular microbial sludge with aerobic microbial sludge. However, in recent years, a method for forming granular sludge (granular microbial sludge) obtained by granulating microbial sludge has been known. (See Patent Documents 1 and 2). The methods described in Patent Documents 1 and 2 utilize a so-called batch-type microbial sludge method. That is, first, the organic waste water is allowed to flow into the aeration tank, and then aerated to perform the aerobic treatment of the organic waste water. Next, the aeration is temporarily suspended and allowed to stand, whereby the treated water obtained by the aerobic treatment of the organic waste water is separated from the solid matter containing microbial sludge, and the treated water is discharged. Then, again, the organic waste water is caused to flow into the aeration tank, and the above cycle is repeated a plurality of times. As described above, the microbial sludge is self-granulated in the aeration tank while the step of aerobic treatment of the organic waste water and the step of settling the solid matter are repeated to form granular microbial sludge.

International Publication No. 98/37027 Pamphlet JP 2005-517532 A

  However, since the microbial sludge is not granulated at the initial stage of starting the wastewater treatment apparatus, the solid sedimentation rate is small. Therefore, it took about 1 to 2 months, for example, to form granular microbial sludge. Thus, when time is required for formation of granular microbial sludge, as a result, organic wastewater may not be treated efficiently.

  Then, this invention aims at providing the granular microbial sludge production | generation method which can produce | generate granular microbial sludge earlier.

  In order to solve the above-mentioned problems, a method for producing granular microbial sludge according to the present invention is a method for producing granular microbial sludge by granulating microbial sludge for aerobic treatment of organic wastewater to produce granular microbial sludge. An inflow process that allows organic wastewater to flow into the aeration tank containing sludge, a treatment process that aerobically treats the organic wastewater by aerating the inside of the aeration tank, and the treated water discharged from the aeration tank by the treatment process. In a solid-liquid separation tank, solids containing microbial sludge are added from a charging process in which a flocculant is added as a granulation accelerator for promoting sludge granulation, and treated water that has been treated in the treatment process and contains the flocculant. A separation step of separating, and a return step of returning the solid separated in the separation step to the aeration tank, and the addition amount when the flocculant is an inorganic flocculant is 10 to 500 mg / l, The minute It added amount when the coagulant is characterized in that a 0.1 to 10 mg / l.

  In this case, the organic waste water that has flowed into the aeration tank in the inflow process is aerobically treated in the treatment process. The flocculant as a granulation accelerator is introduced into the aerobically treated organic waste water in the charging step, and the organic waste water into which the flocculant as the granulation accelerator is charged is solidified in the solid-liquid separation step. Liquid separation. And the solid substance isolate | separated by the isolation | separation process is returned to an aeration tank.

  Since the organic wastewater separated in the solid-liquid separation in the separation step is fed with a flocculant as a granulation accelerator, the microbial sludge, which is a solid in the organic wastewater that has been aerobically treated, settles faster and more. It will be. Since the solids separated in the separation process are returned to the aeration tank in the return process, the flocculant as a granulation accelerator is also introduced into the aeration tank, and the granulation of microbial sludge is promoted. As a result, granular microbial sludge can be generated more quickly.

  In the method for producing granular microbial sludge according to the present invention, a flocculant is used as a granulation accelerator. In this case, since the solid substance which floats in the aerobic-treated organic waste water aggregates with the flocculant, the sedimentation rate of the solid substance is improved. Therefore, for example, when the separation process and the return process are provided, more microbial sludge is returned to the aeration tank. Therefore, association between microbial sludges is likely to occur, and as a result, granulation of microbial sludge is promoted.

  Furthermore, in the method for producing granular microbial sludge according to the present invention, in the charging step, a sedimentation promoting object having a sedimentation speed higher than the sedimentation speed of the microbial sludge can be further charged. By introducing such a sedimentation promoting body, the solid matter containing microbial sludge is induced by the sedimentation of the sedimentation promoting body, and more microbial sludge is sedimented. As a result, the microbial sludge concentration in the aeration tank is easily maintained, the probability that the microbial sludge is associated with each other is increased, and granulation is promoted. Therefore, it is possible to produce granular microbial sludge earlier.

  According to the method for producing granular microbial sludge of the present invention, it is possible to produce granular microbial sludge earlier.

It is a figure which shows the state of the waste water treatment apparatus in the inflow process in a batch type activated sludge process. It is a figure which shows the state of the waste water treatment equipment in the process process in a batch type activated sludge process. It is a figure which shows the state of the waste water treatment apparatus in the stationary process in a batch type activated sludge method. It is a figure which shows the state of the waste water treatment equipment in the discharge process in a batch type activated sludge method. It is a flowchart which shows the basic period of a batch type activated sludge process. It is a figure which shows the state of the waste water treatment apparatus in the stationary process in the batch type activated sludge method in 2nd Embodiment. It is a figure corresponding to the microscope picture of the granular microorganism sludge of the formation initial stage. It is a figure corresponding to the microscope picture of the granular microorganism sludge of the formation initial stage. It is a figure corresponding to the microscope picture of the granular microbial sludge containing about 0.8 mm particle | grains. It is a figure corresponding to the microscope picture of the granular microbial sludge produced | generated when the organic waste water which comes out of a food factory was aerobically processed with the waste water treatment equipment. It is a figure corresponding to the microscope picture of the granular microbial sludge produced | generated when the organic waste water which comes out of a sewage treatment plant was aerobically processed with the waste water treatment equipment. It is a figure which shows the particle image obtained by the simulation using an Eden model. It is a figure which shows the other particle image obtained by simulation by an Eden model. It is a figure which shows the result of having simulated the change of the particle size by the Eden model. It is a figure corresponding to the microscope picture which shows the granular microorganism sludge produced | generated actually. It is a figure corresponding to the microscope picture which shows the granular microorganism sludge produced | generated actually. It is a figure corresponding to the microscope picture which shows the granular microorganism sludge produced | generated actually. It is a figure corresponding to the microscope picture which shows the granular microorganism sludge produced | generated actually. It is a figure corresponding to the microscope picture which shows the granular microorganism sludge produced | generated actually. It is the schematic which shows the structure of the waste water treatment equipment to which 4th Embodiment of the granular microorganism sludge production | generation method of this invention is applied. It is a figure corresponding to the microscope picture of the granular microorganism sludge produced | generated with the waste water treatment apparatus shown in FIG. It is a figure corresponding to the microscope picture of the granular microorganism sludge produced | generated with the waste water treatment apparatus shown in FIG.

  Hereinafter, the best mode of the method for producing granular microbial sludge according to the present invention will be described with reference to the drawings. In the description of the drawings, the same reference numerals are given to the same elements, and duplicate descriptions are omitted.

  (First embodiment)

  One embodiment of the method for producing granular microbial sludge according to the present invention will be described. The granular microbial sludge is a so-called aerobic granular sludge obtained by granulating aerobic microbial sludge. Hereinafter, the microbial sludge and the granular microbial sludge are also referred to as activated sludge.

  The method for producing granular microbial sludge in the present embodiment is performed in the initial stage of organic wastewater treatment by the batch activated sludge method performed in the wastewater treatment apparatus 1 shown in FIGS. First, the waste water treatment apparatus 1 will be described.

  As shown in FIGS. 1-4, the waste water treatment apparatus 1 is equipped with the cylindrical aeration tank 3 which accommodates the activated sludge G for carrying out the aerobic process of organic waste water. FIG. 1 shows a state in which a basic cycle (described later) in the batch activated sludge method is carried out at least once, and a part of the treated water W remains on the activated sludge G as a supernatant. The hatching of the activated sludge G indicates a state in which the microbial sludge G1 and the granular microbial sludge G2 obtained by granulating it are precipitated and deposited.

  In the lower part of the aeration tank 3, an inflow port 5 for allowing the organic waste water to flow into the aeration tank 3 is provided. Moreover, the aeration tank 3 has two discharge ports 7 and 9 for discharging the treated water W obtained by the aerobic treatment of the organic waste water. The discharge port 7 and the discharge port 9 are arranged at different heights. The discharge port 9 is arranged at a position where the height from the bottom surface is 1/10 to 1/2 of the height of the aeration tank 3. The inflow port 5 is disposed below the lower one of the discharge ports 7 and 9. The discharge port 7 may not be provided.

  Further, an inner cylinder 11 is disposed in the aeration tank 3, and an aeration bulb 13 for aerating the inside of the aeration tank 3 is provided in the lower part of the inner cylinder 11. A blower 15 is connected to the air diffuser 13, and air from the blower 15 is blown into the air diffuser 13 to be diffused into the aeration tank 3. The amount of air diffused is 2Nl / min or 4Nl / min. The organic sludge G circulates in the aeration tank 3 by providing the inner cylinder 11 and disposing the air diffuser 13 in the lower part thereof, so that the activated sludge G is further stirred. Note that the inner cylinder 11 may not be provided in the aeration tank 3.

  A typical size of the aeration tank 3 is an effective volume of 3 L, an inner diameter of 63 mm, and a height of 1300 mm (water surface height of 1100 mm). In this case, for example, the discharge port 7 is provided at a position where the height from the bottom surface is 500 mm, and the discharge port 9 is provided at a height of 300 mm. Moreover, as the inner cylinder 11 arrange | positioned in the aeration tank 3 of the said typical magnitude | size, an internal diameter is 40 mm, for example.

The wastewater treatment apparatus 1 includes a tank 17 that contains a flocculant as a granulation accelerator that promotes granulation of the microbial sludge G1 that constitutes a part of the activated sludge G. Examples of the flocculant include inorganic flocculants and polymer flocculants, but any flocculant may be used as long as it has a sludge flocculant effect. Examples of the inorganic flocculant include iron salt and aluminum sulfate (sulfuric acid band), and examples of the polymer flocculant include anionic, nonionic, and cationic polymers. More specifically, those in Table 1 are exemplified.

  The flocculant in the tank 17 is charged into the aeration tank 3 through the charging line L1. The addition amount of the flocculant is, for example, 10 mg / l to 500 mg / l for the inorganic flocculant, and is, for example, 0.1 mg / l to 10 mg / l for the polymer flocculant.

Next, a method for generating granular microbial sludge G2 from microbial sludge G1 using the wastewater treatment apparatus 1 will be described. As described above, the generation of granular microbial sludge G2 is a batch in which organic wastewater is treated by repeating a basic cycle consisting of an inflow step S1, a treatment step S2, a stationary step S3, and a discharge step S4, as shown in FIG. It is performed at the initial stage of the activated sludge process. Table 2 shows a typical time of each process in the basic period.

  Hereinafter, each step will be described.

  In the inflow step S1, as shown in FIG. 1, the organic waste water is caused to flow into the aeration tank 3 having the activated sludge G through the inlet 5. Although the activated sludge G includes the microbial sludge G1 and the granular microbial sludge G2 obtained by granulating the microbial sludge, the activated sludge G in the aeration tank 3 is only the microbial sludge G1 when the waste water treatment apparatus 1 is started up. It's okay.

  In the subsequent processing step S2, as shown in FIG. 2, the blower 15 is driven to blow air to the diffuser sphere 13, and the diffused air is diffused from the diffuser sphere 13 to aerate the organic waste water. The flocculant is added from the tank 17 through the charging line L1 into the aeration tank 3 from the latter half of the processing step S2, for example, about 1 hour before the aeration is stopped.

  In the stationary step S3 after the processing step S2, as shown in FIG. 3, the blower 15 is stopped, aeration is stopped, and the stationary step is performed. Thereby, the solid substance (activated sludge G) which floats on the treated water W obtained by the aerobic treatment of the organic waste water settles, and the treated water W and the activated sludge G are separated into solid and liquid. Subsequently, in the discharge step S4, as shown in FIG. 4, the treated water W, which is a supernatant after solid-liquid separation, is discharged from the discharge ports 7 and 9.

  The basic cycle composed of the inflow step S1, the processing step S2, the stationary step S3, and the discharge step S4 is repeated, for example, eight times per day. By repeating the basic cycle in this manner, the microbial sludge G1 is self-granulated and a granular microbial sludge G2 having a large particle size is generated when aerated in the treatment step S2.

  In the batch activated sludge method, organic wastewater is pulsed into the aeration tank 3, so that the microorganism sludge G1 is provided with a substrate (organic matter) as a nutrient contained in the organic wastewater ( A state of satiety) and a state of no grant (starvation) are repeatedly given. As described above, since the microbial sludge G1 ingests a lot of nutrients after being starved after being starved, an extracellular polymer is easily formed, and the microbial sludge G1 is easily self-granulated.

  Thus, when microbial sludge G1 is granulated and particle microbial sludge G2 having a particle size of 1 mm to 3 mm or a particle sedimentation speed of 5 m / hr or more is generated in a predetermined amount, the aerobic treatment of organic waste water is continued, for example. The organic waste water may be aerobically treated by stopping the addition of the flocculant as the granulation accelerator.

  In the method for producing granular microbial sludge, it is important to add a flocculant as a granulation accelerator that promotes granulation of the microbial sludge G1.

  In the conventional batch activated sludge method in which no flocculant is added, the microbial sludge has a tendency to be difficult to settle in the stationary step because the sedimentation rate of the microbial sludge is small. Therefore, a lot of microbial sludge is discharged outside the aeration tank in the discharge process, and unless the sludge is added, the concentration of microbial sludge in the aeration tank may be reduced and it may be difficult to generate granular microbial sludge. In addition, since the amount of microbial sludge flowing out is large, equipment for separating microbial sludge again from the discharged treated water is required. Furthermore, the microbial sludge that has been allowed to settle by lengthening the stationary process tends to be difficult to produce granular microbial sludge, and it took 1-2 months.

  On the other hand, in the method for producing granular microbial sludge in which the flocculant is added, the microbial sludge G1 and the granular microbial sludge G2 are agglomerated by the sludge aggregating effect of the flocculant added to the aeration tank 3 in the latter half of the treatment step S2. For example, even in a stationary step S3 as short as 3 minutes as shown in Table 2, the activated sludge G settles quickly. The microbial sludge G1 settled early in this way is easily granulated, and the generation of the granular microbial sludge G2 is promoted. Moreover, since more microbial sludge G1 settles, the separation of the treated water W and the activated sludge G can be ensured. Therefore, the equipment for further separating the microbial sludge G1 from the discharged treated water W is not required, and the wastewater treatment apparatus 1 can be downsized. Since the discharge of the microbial sludge G1 can be reduced, the decrease in the microbial sludge concentration in the aeration tank 3 can be suppressed. As a result, the probability that the microbial sludge G1 is associated with each other increases, and the granular microbial sludge G2 is easily generated.

  Furthermore, since the thickness of the sedimentation layer of the activated sludge G that has settled is reduced by the coagulation effect of the coagulant, the position of the discharge port 9 is set to about 1/10 to 1/1 of the height of the aeration tank 3 as described above. It can be set to about 2 and lower than the conventional level. Here, the reason why the position of the discharge port 9 is preferably 1/10 to 1/2 of the height of the aeration tank 3 will be described.

  Usually, the settleability of activated sludge is expressed using SVI (sludge volume index). This SVI is obtained by taking activated sludge in a 1 L graduated cylinder and allowing it to stand for 30 minutes and measuring its volume SV and MLSS. In a normal aeration tank, SVI is considered to be an appropriate value from 50 to 150.

  Therefore, when 3000 mg / l is considered as a representative MLSS, even if it is the initial activated sludge, if it is allowed to stand for 30 minutes, it becomes 150 ml to 450 ml, which is three times 50 to 150 unless bulking is performed. In this case, if the flocculant is not used, the SV becomes large after standing for 3 minutes. However, if the flocculant is concentrated as much as the standing for 30 minutes by using the flocculant as described above, 150 to The outlet 9 can be arranged at 450 ml. This corresponds to a position of 150 mm to 450 mm in the height of the treated water in a 1 L graduated cylinder. As a result, by arranging the discharge ports 9 at about 1/10 to 1/2, the aeration tank 3 The treated water W can be discharged at a position slightly higher than the thickness of the activated sludge G accumulated in the lower part. Therefore, the activated sludge G can come into contact with the organic wastewater having a higher concentration.

  As understood from the above, the height of the discharge port 9 is preferably about the thickness of the solid matter containing the microbial sludge G1 when the microbial sludge G1 in the aeration tank 3 is all settled.

  Thus, since the discharge amount of the treated water in the discharge step S4 can be increased by lowering the position of the discharge port 9 than before, when the organic wastewater newly flows into the aeration tank 3 in the inflow step S1, The activated sludge G comes into contact with a high concentration organic waste water, that is, a high concentration substrate.

  By the way, by repeating the basic cycle, when the microbial sludge G1 is granulated in the activated sludge G and becomes larger in particle size, the nutrients tend not to penetrate into the microbial sludge G1 having a larger particle size. .

  On the other hand, when the granular microbial sludge G2 can be brought into contact with the organic wastewater having a high concentration as described above, the substrate (organic matter) contained in the organic wastewater is surely contained inside the microbial sludge G1 that is being granulated. To penetrate. Thereby, the granulation of the microbial sludge G1 is further promoted, and the granular microbial sludge G2 is easily generated. Moreover, since the inflow port 5 is provided below the discharge port 9, the organic waste water flows directly into the activated sludge G. Therefore, since the activated sludge G comes into contact with the organic wastewater having a higher concentration, the generation rate of the granular microbial sludge G2 is improved. As a result, conventionally, it took 1-2 months to generate granular microbial sludge G2, but for example, granular microbial sludge G2 can be generated in 1-2 weeks.

  And since the granular microbial sludge is rapidly formed at the initial stage of the batch activated sludge method, the treatment efficiency of the organic waste water is increased, and the organic waste water can be efficiently aerobically treated.

  In addition, it is preferable to arrange | position the inflow port 5 in the bottom face of the aeration tank 3 from a viewpoint of making organic wastewater flow directly into the solid substance containing the microorganism sludge G1 settled in the lower part of the aeration tank 3.

  (Second Embodiment)

  The granular microbial sludge generation method in the second embodiment is the first in that a sedimentation promoting object for promoting sedimentation of activated sludge G is introduced into the aeration tank 3 in the stationary step S3 as shown in FIG. This is different from the method for producing granular microbial sludge in the embodiment.

  The sedimentation promoting body has a sedimentation speed equal to or higher than the sedimentation speed of the microbial sludge G1, and forms a so-called water supply (flow from the upper side to the lower side) by sinking together with or earlier than the microbial sludge G1. Inducing sedimentation of microbial sludge G1. Examples of the settling speed of the settling acceleration body include 5 m / hr to 80 m / hr.

  The material and structure of the sedimentation promoting object are not particularly limited as long as the sedimentation speed as described above can be realized. For example, the sedimentary acceleration object is made of plastic and has a spherical or square shape from the viewpoint of ease of production and processing. And as for the magnitude | size of a sedimentation acceleration | stimulation object, when a shape is a square, 5 mm-10 mm square is illustrated, and when a shape is spherical, the diameter is 5 mm-10 mm. Further, as described above, since the sedimentation promoting object induces sedimentation of the microbial sludge G1, it is preferable that the volume is large. However, if the volume is too large, the utilization efficiency of the aeration tank 3 is lowered. The volume of the object is preferably 10% or less of the volume of the aeration tank 3.

  Furthermore, since the sedimentation promoting object is once subjected to the processing step S2, the specific gravity of the sedimentation promoting object is such that it is stirred and fluidized in the processing step S2, and the sedimentation speed is set in the stationary step S3. What is feasible is preferred. Further, the sedimentation promoting object is preferably strong enough to prevent the wear due to stirring in the processing step S2.

  As described above, when such a sedimentation promoting object is introduced into the aeration tank 3 in the stationary step S3, the microbial sludge G1 is also sedimented by being induced by sedimentation of the sedimentation promoting object. As a result, more microbial sludge G1 and microbial sludge G1 that are being granulated will settle within the time of the stationary step S3 of 3 minutes as shown in Table 2. Thereby, the density | concentration of microbial sludge G1 in the aeration tank 3 can be maintained, and the probability of the association of microbial sludge G1 increases. As a result, granulation of the microbial sludge G1 is promoted, and the granular microbial sludge G2 is generated earlier.

  The sedimentation promoting object may be introduced at least once out of a plurality of repetitions of the basic period, for example, it may be introduced at the very first stationary step S3.

  (Third embodiment)

  The granular microbial sludge generation method of the third embodiment is different from the granular microbial sludge generation method of the first embodiment in that a nuclear material serving as the nucleus of the granular microbial sludge is input instead of the flocculant. The nuclear material is accommodated in the tank 17 and is charged into the aeration tank 3 via the charging line L1 in the latter half of the processing step S2. Examples of nuclear materials include protozoa and filamentous fungal sludge. Moreover, the thing which has a property equivalent to the granular microorganism sludge with a magnitude | size of 0.2 mm-1.0 mm may be sufficient. Here, the size of the nuclear material is, for example, the diameter when the nuclear material is spherical.

  Here, the production of granular microbial sludge G2 by introducing protozoa or filamentous fungal sludge as a nuclear material, or by introducing a nuclear material having a size of about 0.2 mm to 1.0 mm as described above. Explain that is promoted.

  The present inventors conducted earnest research on the mechanism of formation of granular microbial sludge, and when observing the granular microbial sludge G2 at the initial stage where granulation began, for example, when the particle diameter is smaller than 0.2 mm, We obtained knowledge that a large amount of protozoa and filamentous fungi exist.

  FIG. 7 is a diagram corresponding to a microphotograph of granular microbial sludge at the initial stage of formation, and shows that Alcera, which is a protozoa, is included in the granular microbial sludge G2. Moreover, FIG. 8 is a figure corresponding to the microphotograph of the granular microbial sludge of the formation initial stage, and has shown that the granular microbial sludge G2 is formed when the filamentous fungi are intertwined. In addition, as a result of observing the initial formation of various granular microbial sludges G2, there were cases where filamentous fungi were used alone or formed by involving flock-like microbial sludge G1. The size of the protozoa contained in the initial stage of the formation of the granular microbial sludge G2 is, for example, about 10 μm to 30 μm, and the size of the filamentous fungus is about several hundred μm. At the initial stage of granulation, the generation of nuclei of about 10 μm to 100 μm was involved.

  Furthermore, the present inventors have found that in the production of granular microbial sludge G2, there is a stage characterized by a size of 0.2 mm to 1.0 mm as the next stage in the initial stage of formation. FIG. 9 is a diagram corresponding to a micrograph of the granular microbial sludge G2, and shows that particles of about 0.8 mm are present.

  The present inventors used simulation to verify the knowledge that it is possible to increase the production rate of granular microbial sludge by introducing a nuclear material having a size of 0.2 mm to 1.0 mm. First, as a model for the generation of granular microbial sludge, the present inventors are known as a DLA model in which agglomeration growth to a seed (nucleus) is modeled under diffusion rate control, an Eden model known as a cancer cell growth model, and the like. As a result of studying a KLG (Kinetics Limited Growth) model (thermal rate limiting model) under high concentration conditions, the Eden model was adopted for the following reasons.

  FIG. 10 is a diagram corresponding to a micrograph of granular microbial sludge generated when the present inventors have performed an aerobic treatment of organic wastewater from a food factory using a wastewater treatment apparatus. Moreover, FIG. 11 is a figure corresponding to the microphotograph of the granular microorganism sludge obtained when the present inventors performed the aerobic treatment of the waste_water | drain from a sewage treatment plant | facility with a waste water treatment equipment.

  12 and 13 are simulation results based on the Eden model, and are diagrams for comparing an image obtained by the simulation with an actually generated granular microbial sludge image. In the simulation for obtaining the image shown in FIG. 12, the flow rates in the vertical direction and the horizontal direction (two directions orthogonal to each other) are the same, whereas in the simulation for obtaining the image shown in FIG. There is a difference in flow velocity in two orthogonal directions.

  Also, the difference between the cases of FIGS. 12A to 12C and FIGS. 12D to 12F corresponds to the difference in the number of nuclei per unit volume. The case of (a) to FIG. 12 (c) corresponds to the case where the number of nuclei per unit volume is larger. The same applies to the difference between the case of FIGS. 13A to 13C and the case of FIGS. 13D to 13F. 12A to 12C show a process in which particles grow in the order of FIGS. 12A, 12B, and 12C. 12 (d) to 12 (f) show a process in which particles grow in the order of FIG. 12 (d), FIG. 12 (e), and FIG. 12 (f). The same applies to FIGS. 13 (a) to 13 (c) and FIGS. 13 (d) to 13 (f).

  When FIG. 10 is compared with FIG. 11, the granular microbial sludge that is actually generated becomes circular (actually spherical) as shown in FIG. 10, or becomes elliptic as shown in FIG. It turns out that it may be. When it becomes elliptical as shown in FIG. 11, for example, there is a difference of 1:10 in the flow velocity in two orthogonal directions, and the flow in the aeration tank is non-uniform. On the other hand, when FIG. 12 and FIG. 13 are compared, in the simulation based on the Eden model, particles grow in a circular shape and an elliptical shape due to a difference in flow velocity conditions. Thus, the Eden model clearly shows the shape of granular microbial sludge, and it can be seen that the generation of granular microbial sludge can be simulated. As described above, the present inventors have examined other models and determined that the Eden model is suitable for the simulation of the generation of granular microbial sludge.

  And the present inventors performed the simulation of the production | generation of granular microbial sludge by making an activated sludge adhere randomly on the circumference which modeled the nuclear material in the Eden model. Specifically, α is dependent on n · v when the growth, ie, the particle size (mm) is α, the number of nuclear materials is n, and the flow velocity is v, that is, the particle size is the nuclear material. The simulation was carried out assuming that the number n was correlated with the flow velocity v. At this time, when the particle size is 0.5 mm, the flow rate is 8 m / min, and when the number n of nuclear materials is 5800 and 29000, the diameter of the granular microbial sludge G2 is set with respect to time. Asked.

  The simulation result by the present inventors is shown in FIG. The simulation results shown in FIG. 14 are in good agreement with the actual measurement values. Furthermore, it has been found from calculations that rapid nuclear growth occurs when the particle size is 0.2 mm to 1.0 mm.

  Based on the above findings, in the production of granular microbial sludge G2, protozoa and filamentous fungi are introduced as nuclear materials, or as a nuclear material, about 0.2 mm to 1.0 mm granular microbial sludge or the like. The two stages in the production of the granular microbial sludge G2 are respectively induced. As a result, the production of granular microbial sludge is promoted. In addition, when a nuclear material having a thickness of 0.2 mm to 1.0 mm is introduced, a material having a thickness of 0.5 mm is more preferable.

  Examples of the protozoa to be introduced include flesh, flagella, cilia (free swimming type), cilia (striped), and suction tube, and more specifically, Are illustrated.

  Zooglea ramigera, Sphaerotilus natans, Monas amoebina, Poteriodendron peticlatum, Entosiphon sulcatum, Mayorella peni, Mayorella peni , Dinamoeba mirabilis, Metachaosgratum, Striamoebastriata, Thecamoebaverrucosa, Cochliopodiumbilimbosum, xi vululata, xi vul sul (Acure Airta), Euglypha tuberculata (Euglypha hutchinsoni), Euglypha hutchinsoni (Euglypha hatch) Sonny, Trinemaenchelys, Actinophyrys sol, Colpoda inflata, Linotosolamella, Trithigmostoma cucullulus, vorticella alba, vorticella alba, vorticella alba Combararia), Vorticella infusionum, Vorticella microstoma, Vorticella nutans, Epistylis entzii, Epistylis plicatilis, rot Oper, rotia rot Opelclaria filiganeae), Opercularia minima, Operculariacoarctata Laria Coarcata).

  Examples of the filamentous fungi include Sphaerotilus natans, Beggiatoa alba, Thiothrix, Haliscomenobacter hydrossis, Microthrixparvicella, Nostocoida limicola, Nocardia, and Rhodococcus. What has been propagated) may be used.

(1) A filamentous fungus is generated (growth) by using wastewater rich in carbohydrates. Examples of carbohydrates for producing filamentous fungi include sugars such as glucose, sucrose, and lactose, and water-soluble low-molecular-weight organic substances that are very easily assimilated. For example, filamentous fungi can be generated using organic wastewater containing 900 mg / l glucose, 300 mg / l peptone, and 200 mg / l meat extract. As another example, organic waste water containing 1500 mg / l CSL (corn steep liquor), 1500 mg / l glucose, 100 mg / l K ₂ HPO ₄ , 100 mg / l KCL, 50 mg / l MgSO ₄ Even when used, filamentous fungi can be generated.

  Furthermore, it is also possible to generate filamentous fungi using (2) anaerobic fermentation products. Furthermore, (3) it is possible to generate filamentous fungi by treating organic wastewater with an excessive or excessive drainage load. As an example of the excessive load amount, there is a case where the BOD sludge load is 1 kg-BOD / kg-MLSS / d. Further, as an example of an underload, the load is 0.05 kg-BOD / kg-MLSS / d as the BOD sludge load.

  In addition, as the protozoa and the filamentous fungus, the above-mentioned various things may be added alone, or a plurality of them may be added in combination. The input amount is exemplified by about 1% of the volume of the aeration tank 3. More specifically, in the case of protozoa, for example, it is 50 mg / l to 500 mg / l, and in the case of filamentous fungi, for example, it is 500 mg / l to 1500 mg / l.

  FIGS. 15-19 is a figure which shows the microscope picture of the granular microorganism sludge G2 produced | generated by the granular microorganism sludge production | generation method shown in this embodiment using the waste water treatment apparatus 1 shown in FIG.1 and FIG.2. The size of the aeration tank 3 when the granular microbial sludge G2 was generated was the above-described typical size, that is, an effective volume of 3 L, an inner diameter of 63 mm, and a height of 1300 mm (water surface height of 1100 mm). And the discharge port 7 was provided in the position whose height from a bottom face is 500 mm, and the discharge port 9 was provided in the height of 300 mm. Further, an inner cylinder 11 having an inner diameter of 40 mm was disposed.

Further, the aeration tank sludge concentration is 3000 mg / l, the substrate concentration is 500 kg-CODcr / m ³ / d, the sludge load is 0.5 kg-CODcr / kg-MLSS / d, and the volume load is 1.6 kg-CODcr / m ³ / d. d. Furthermore, when producing the granular microbial sludge G2 shown in FIGS. 15 to 19, protozoa and filamentous fungi produced under conditions where they are generated or proliferated are accommodated in the tank 17 and introduced. The input amount was about 200 mg / l for protozoa and about 1000 mg / l for filamentous fungi. The granular microbial sludge G2 shown in FIGS. 15 to 19 is produced in 1 to 2 weeks.

  FIG. 15 shows the appearance of the generated granular microbial sludge G2. FIG. 16 shows that the protozoan Alcera is contained in the granular microbial sludge G2. FIG. 17 shows that various protozoa are incorporated into the granular microbial sludge G2. FIG. 18 shows that protozoa are incorporated into the granular microbial sludge G2. FIG. 19 shows that protozoa and filamentous fungi are taken together in the granular microbial sludge G2.

  From FIG. 15 to FIG. 19, it can be seen that by introducing protozoa and filamentous fungi, it is possible to produce granular microbial sludge G2 that has surely incorporated them. As a result, what conventionally took about 1 to 2 months for generation can be shortened to 1 to 2 weeks, for example.

  (Fourth embodiment)

  FIG. 20 is a schematic diagram showing the configuration of a wastewater treatment apparatus for applying the method for producing granular microbial sludge according to the fourth embodiment. The granular microorganism sludge generation method of the fourth embodiment is carried out in the initial stage of the continuous activated sludge method.

  The waste water treatment device 19 contains activated sludge G and has an aeration tank 21 for aerobic treatment of organic waste water. Organic waste water flows into the aeration tank 21 through the inflow line L2. A plurality of nozzles 23 connected to the blower 15 are provided below the aeration tank 21. A solid-liquid separation tank 25 is disposed downstream of the aeration tank 21, and treated water obtained by aerobic treatment of organic wastewater in the aeration tank 21 is introduced into the solid-liquid separation tank 25 through a drain line L3. The

  The solid-liquid separation tank 25 settles solids (solid microbial sludge G1 and granular microbial sludge G2) contained in the treated water flowing through the drainage line L3 and separates them into solid and liquid. One end of a return line L4 for returning surplus sludge, which is a settled solid matter, to the aeration tank 21 is connected to the lower part of the solid-liquid separation tank 25, and the other end of the return line L4 is connected to the inflow line L2. Has been. The solid-liquid separation tank 25 is connected to a discharge line L5 for discharging the supernatant obtained by solid-liquid separation.

  Moreover, the waste water treatment device 19 includes a tank 17 that contains a flocculant as a granulation accelerator. The tank 17 is connected to the drainage line L3 by the charging line L1, and the flocculant is charged into the aerobically treated organic wastewater flowing through the draining line L3. The input amount is the same as in the case of the first embodiment. For example, the inorganic flocculant is, for example, 10 mg / l to 500 mg / l, and the polymer flocculant is, for example, 0.1 mg / l to 10 mg / l. . As a result, treated water that has been subjected to aerobic treatment and into which the flocculant has been introduced flows into the solid-liquid separation tank 25.

  In addition, as shown in FIG. 20, it is suitable to install the mixing means 27 for mixing the flocculant and the treated water on the drain line L3. Examples of the mixing means 27 include a mixer and a mixing tank, and it is further preferable to use a stirrer 29 together as shown in FIG. This is because by installing such a mixing means 27, the treated water and the flocculant are mixed more uniformly.

  The production | generation method of the granular microorganism sludge G2 using this waste water treatment apparatus 19 is demonstrated. Here, it is assumed that the aeration tank 21 is aerated by driving the blower 15.

  Organic wastewater is caused to flow into the aeration tank 21 through the inflow line L2 (inflow process), and aerobic treatment is performed with the activated sludge G in the aeration tank 21 (processing process). The treated water obtained by the aerobic treatment of the organic wastewater flows into the solid-liquid separation tank 25 through the drainage line L3. At this time, the flocculant is charged from the tank 17 through the charging line L1 (charging process). Then, in the solid-liquid separation tank 25, the treated water is subjected to solid-liquid separation (separation step), and the supernatant is discharged from the discharge line L5. Moreover, in the solid-liquid separation tank 25, the settled solid matter is discharged from the return line L4 as surplus sludge, introduced into the organic waste water flowing through the inflow line L2, and flows into the aeration tank 21 together with the organic waste water (return process). .

  If a predetermined amount of granular microbial sludge G2 can be generated when the waste water treatment device 19 is started up by the above-described continuous activated sludge method, the flocculant is stopped and the organic waste water is aerobically treated.

  In this method, since the flocculant is thrown into the treated water flowing through the drain line L3, the solid matter containing more microbial sludge G1 settles in the solid-liquid separation tank 25 due to the flocculant effect of the flocculant. Furthermore, the floc-like microbial sludge G1 is concentrated at a high density. Therefore, the solid-liquid separation tank 25 can be downsized.

  Furthermore, since the return line L4 is connected to the inflow line L2, the returned solid matter is put into the organic waste water. As a result, for example, even if the particle size becomes larger due to granulation of the microbial sludge G1, it is possible to penetrate organic matter (BOD, COD, TOC), nitrogen, phosphorus, etc. contained in the organic wastewater to the inside. . Therefore, granulation of the microbial sludge G1 can be continued.

  Thereby, in order to produce | generate conventionally the granular microbial sludge G2, although it took 1-2 months, the production | generation of the granular microbial sludge G2 is attained in a shorter period, for example, 1-3 weeks.

  The granulation accelerator may be the nuclear material described in the third embodiment. In this case, as in the case of the flocculant, the nuclear material is preferably put into the drainage line L3. As in the case of the third embodiment, protozoa and filamentous fungi are suitable as nuclear materials, and 0.2 to 1.0 mm granular microbial sludge or those having similar properties are also effective. It is.

  21 and 22 are diagrams corresponding to micrographs of granular microbial sludge G2 actually produced using protozoa and filamentous fungi as granulation accelerators. The conditions when the granular microbial sludge G2 is generated are as follows.

That is, the aeration tank sludge concentration is 4000 mg / l, the sedimentation tank sludge concentration is 8000 mg / l, the substrate concentration is 1500 kg-CODcr / m ³ / d, the sludge load is 0.2 kg-CODcr / kg-MLSS / d, and the volume load is Particulate microbial sludge G2 was produced at 1.1 kg-CODcr / m ³ / d. The input amount of protozoa was 500 mg / l, and the input amount of filamentous fungi was 1500 mg / l. By generating granular microbial sludge G2 under the above conditions, granular microbial sludge G2 could be generated in about 3 weeks.

  Although the best embodiment of the present invention has been described above, the present invention is not limited to the first to fourth embodiments.

  For example, the sedimentation promoting object described in the second embodiment may be introduced alone as described in the second embodiment, but the first embodiment, and the third and fourth embodiments. May be combined. That is, in the first embodiment (third embodiment), a flocculant (protozoa and filamentous fungus) may be introduced in the latter half of the treatment process, and further, a sedimentation promoting object may be introduced in the stationary process. In the fourth embodiment, a flocculant, a granulation accelerator such as a protozoan or a filamentous fungus may be added to the drain line L3, and a sedimentation promoting substance may be input. Moreover, when combining 2nd and 4th embodiment, you may throw a sedimentation promoting body into a solid-liquid separation tank directly.

  Furthermore, in the first and third embodiments, the granulation accelerator is introduced in the latter half of the treatment process, but may be introduced in a stationary process. Further, the size of the aeration tank 3 is not limited to the typical size described above. The size of the aeration tank 3 is appropriately designed depending on the discharge amount of the treated water. However, the solid sedimentation rate is the same as the above typical size, for example, the sedimentation rate is 5 m / hr to 80 m / hr. It is preferable to change to be hr.

  DESCRIPTION OF SYMBOLS 1 ... Waste water treatment apparatus 3,21 ... Aeration tank, 5 ... Inflow port, 7 ... Discharge port, 9 ... Discharge port, 11 ... Inner cylinder, 13 ... Air diffuser, 15 ... Blower, 17 ... Tank, 19 ... Waste water treatment Apparatus, 23 ... Nozzle, 25 ... Solid-liquid separation tank, 27 ... Mixing means, 29 ... Stirrer, G ... Activated sludge, G1 ... Microbial sludge, G2 ... Granular microbial sludge.

Claims (2)

A method for producing granular microbial sludge by granulating microbial sludge for aerobic treatment of organic wastewater to produce granular microbial sludge,
An inflow step of allowing organic wastewater to flow into the aeration tank containing the microbial sludge;
A process for aerobic treatment of the organic waste water by aeration in the aeration tank;
An input step of adding a flocculant as a granulation accelerator for promoting the granulation of the microbial sludge to the treated water treated in the treatment step and discharged from the aeration tank;
A separation step of separating the solid matter containing the microbial sludge in a solid-liquid separation tank from the treated water treated in the treatment step and containing the flocculant;
A return step for returning the solid matter separated in the separation step to the aeration tank,
The addition amount when the flocculant is an inorganic flocculant is 10 to 500 mg / l,
The method for producing granular microbial sludge, wherein the addition amount when the flocculant is a polymer flocculant is 0.1 to 10 mg / l.   The method for producing granular microbial sludge according to claim 1, wherein in the charging step, a sedimentation promoting object having a sedimentation speed equal to or higher than the sedimentation speed of the microbial sludge is further charged.

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