JPS60166093A - Method and device for controlling fluidized-bed biological treating apparatus - Google Patents

Abstract

PURPOSE:To keep stably the amt. of microorganisms in a vessel, and to treat stably by taking out solid particles in the vessel so that the measured value of SV of a sample taken from mixed liquid in the vessel may be within the appropriate range, stripping off the film of the microorganisms, and returning the solid particles to the inside of the vessel. CONSTITUTION:A sample of a mixed liquid in a vessel is taken from circulation part 6 in the vessel 4 with a sample-taking pump 10, and sent to an automatic SV measuring device 11. The measuring signal from the automatic SV measuring device 11 is sent to a comparator arithmetic unit 15, and compared with a present upper limit value of SV. When the measured value exceeds the upper limit value, the mixed liquid in the vessel is sent to a microorganism stripping device 18 through a controller 16 by operating a pump 17. The microorganism film on the surface of the solid particle is rubbed and washed with stripping particles, and stripped while the introduced solid particles coated with microorganisms pass through the vessel. And the solid particles, along with the microorganisms, are returned to the fluidized-bed biological treating vessel 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention involves suspending solid particles as microbial carriers in a tank, and stirring the solid particles through an air lift pipe installed in a button inside the tank. The present invention relates to a method and apparatus for controlling the amount of microorganisms adhering to solid particles in a fluidized bed biological treatment apparatus that circulates and fluidizes solid particles.

[Prior art]

Recently, various biofilm-type sewage treatment systems have been put into practical use that have solved the bulking phenomenon and complexity of maintenance in the activated sludge method, such as tube catalytic oxidation, one rotating disk method, and one granular solid fluidized bed method. has been done. Of these,
Microorganisms are attached to the surface of solid particles at a concentration of % iq in a tank, and the solid particles are circulated and flowed in the tank while gas agitation is carried out through an air lift pipe installed in the tank to bring them into contact with wastewater. The granular solid fluidized bed method, which removes pollutants from wastewater, can hold a large amount of microorganisms in the tank because the surface area of the solid particles for microbial attachment is dramatically larger than other biofilm methods. point.

It is attracting attention because it has many advantages, such as the fact that solid particles circulate and flow inside the tank, so problems such as partial anaerobic formation do not occur if the moon becomes clogged.

In this granular solid fluidized bed method, materials such as sand, anthracite, activated carbon, zeolite, and plastic spheres are suitable for the attachment of microorganisms, and have specific gravity and particles suitable for smooth circulation and fluidization within the tank. Solid particles with a diameter are used, but 1 usually.

Considering the price and difficulty of obtaining, sand is often used.

Further, the air lift tube has an air introduction tube connected to its lower part, and solid particles circulate inside and outside the air lift tube due to the air lift action of the air blown into the tube. A part or the entire circumference above the tank where the air lift pipe is installed is divided into a circulation part and a separation part by a corner wall whose upper end is above the water surface and whose lower end is below the water surface. Part of the V suspension.

While rising through this separation section, solid particles are separated and taken out from above as effluent water. Furthermore, this runoff water is sent to coagulation sedimentation, sand filtration equipment, etc. as a post-treatment equipment.
88. in the effluent. After undergoing treatments such as BOD and COD removal, it becomes final treated water.

By the way, in the conventional fluidized bed apparatus, as the treatment continues, microorganisms proliferate on the surface of the granular solids, the particles become enlarged, the apparent density decreases, the particles gradually become lighter, and the sedimentation rate decreases. As a result, the separation section can no longer completely separate the water and the water flows out of the tank along with the outflow water.

As a result, the amount of microorganisms in the tank decreases, which not only reduces the functionality of the biological treatment device, but also causes problems such as clogging and wear of the coagulation sedimentation device and sand filtration device in the downstream stages, and the wastewater treatment device This will cause a fatal problem. In conventional fluidized bed equipment, in order to avoid such troubles, the area of the part fn was designed to be as large as possible, but in that case, to what extent microorganisms could adhere and settle. It is obvious to what extent particles whose velocity has decreased should be separated, so the design must be designed with excessive force, but if it is too large, it will cause suspended SS to accumulate in the tank. This often causes new problems such as preventing the adhesion of microorganisms and further reducing the separation rate due to the crosslinking of the SS, promoting particles to flow out of the tank.

[Purpose of the invention]

The present invention makes it possible to easily and accurately grasp the microbial landscape in a tank, that is, the amount of microorganisms attached to solid particles, to control the amount of microorganisms attached to solid particles, and to prevent the microorganisms attached to the particles from flowing out of the tank. However, it is an object of the present invention to provide a control method and a control device for a fluidized bed biological treatment apparatus that can eliminate the above-mentioned conventional problems at once and continue stable and high-performance treatment.

[Structure of the invention]

The present invention provides biological treatment in which solid particles are suspended as microbial carriers in a tank, and a fluidized bed is formed in which the solid particles are circulated and fluidized by agitating gas through an air lift pipe installed in the tank. In the device, take a sample of the mixed liquid in the tank and measure the SV value, i.e. 7-, to ensure that the SV value is within the appropriate range.

A control method and a control device for a fluidized bed biological treatment apparatus are characterized in that solid particles in the tank are extracted, microbial membranes are removed, and then returned to the tank.

〔Example〕

Further, one embodiment of the present invention will be described below with reference to the drawings.

In the first illustrated example, the interior of the fluidized bed biological treatment tank 4, which has a raw water inflow pipe 1 and a treated water outflow pipe 2 and contains granular solids 6 for attaching microorganisms, has an upper end above the water surface and a lower end below the tank bottom. A circulation part 6 and a separation part 7 are divided by an isolated partition wall 5, and the circulation part B has an upper end below the water surface, a lower end isolated from the tank bottom, and an air introduction pipe 8 connected to the vicinity of the lower end. In the fluidized bed biological treatment equipment in which the air lift pipe 9 is installed, the raw water introduced into the air lift pipe 9 is circulated and flows in the tank 4 due to the air lift action of the air blown into the air lift pipe 9. Organic matter in the water is decomposed and removed by the action of attached microorganisms.

Then, a part of the liquid in the tank flows into the first separation section 7, where the microorganism-attached particles are sedimented and separated, and then flowed out as treated water from the treated water outflow pipe 2 in the upper part.

As this treatment progresses, microorganisms proliferate on the surface of the solid particles, so each particle becomes enlarged and increases in volume, and gradually its apparent density decreases and becomes lighter. If the particles become too large and too light, they will overcome the upward flow velocity in the separation section 7 and will not be able to settle and separate, and will flow out of the tank together with the treated water. It is necessary to extract the attached solid particles and peel off the microbial film.

There is a good correlation between the degree of adhesion of microorganisms and the sedimentation capacity of solid particles adhering to them, as shown in Figure 2.
By measuring the sedimentation capacity of the microorganism-adhered solid particles occupying a certain amount of the mixed liquid in the tank, it becomes possible to control the degree of adhesion of microorganisms, that is, the amount of microorganisms in the tank. In other words, periodically collect the mixed liquid in the tank.

Check whether the SV value is within the appropriate range. If it exceeds the upper limit of the appropriate range, extract the mixed liquid from the tank, peel off the microbial film from the solid particles, and return it to the tank. This is continued until the SV value falls within the appropriate range.

FIG. 1 shows an example of automating this operation, in which a sample of the mixed liquid in the tank is collected, for example, from the internal circulation section 6 of the tank 4 using the sample collection pump 10, and the SV automatic measuring device 11
send to As illustrated in FIG. 3, the SV automatic measuring device 11 includes a light source and a light receiver that sandwich the cylinder 12 when an appropriate amount of sample of the mixed liquid in the tank is collected into the cylinder 12 by the sample collection pump 10. R can be moved up and down by a motor, and starts from the water surface position A of the cylinder 12 and descends while following the interface of the sedimented particle group by a servo mechanism. The SV value is determined by the SV measurement unit 13 from the interface position B and the above-mentioned A position after a predetermined time.

After the measurement is completed, the sample is drained from the cylinder 12, and the cylinder is cleaned with fresh water and air.

All of these steps are controlled by a sequence controller 14. Note that the measurement time is arbitrarily determined in consideration of the sedimentation speed of the particles, but it is usually 5 to 60 minutes.

Next, the measurement signal from the Sv automatic measuring device 11 is sent to the comparator 15 and compared with a preset SV upper limit value. The extraction pump 17 is operated, and the extracted mixed liquid in the tank is sent to the microbial film stripping device 18.

FIG. 4 shows an example of the microbial membrane peeling device 18, in which peeling particles 19 having a particle size smaller than that of a granular solid are contained inside.
are contained and mixed by a stirrer 20, and while the introduced microbial-adhered solid particles pass through the tank, they are massaged and washed by the peeling particles 19, and the microbial film on the solid particle surface is peeled off, and together with the microorganisms, they are fluidized. It is returned to the floor biological treatment tank 4. This step is repeated until the SV falls within the appropriate range, so that the solid particles 6 are constantly prevented from becoming enlarged, solid particles do not flow out of the tank, and stable processing is continued.

In the above embodiment, the sample collection pump 10 and extraction pump 17 are used to take out the mixed liquid in the tank, but if the head difference can be used, only an on-off valve can be used instead of these pumps. It can be operated with. In addition, the microbial film peeling device 18 does not have to be provided outside the tank 4 (it can be replaced by providing a stirrer in a part of the tank, and its drive device is operated by the SV value of the comparator 15). It can also be done.

As described above, according to the present invention, the microbial adhesion to suspended solid particles in a fluidized bed biological treatment device is accurately grasped, and the microbial adhesion fleas are controlled to be within an appropriate range in a timely manner.
The amount of microorganisms in the tank can be stably maintained, solid particles do not flow out of the tank, and stable and high-performance processing can be continued.

[Brief explanation of the drawing]

The drawings show examples of the present invention, and FIG. 1 is a longitudinal sectional view, and FIG. 2 is a diagram showing the relationship between the degree of adhesion of microorganisms and the sedimentation capacity of solid particles attached to the microorganisms. FIG. 3 is an explanatory diagram showing a part of the automatic control device, and FIG. 4 is a longitudinal cross-sectional view showing an example of the microbial film peeling device. 1... Raw water inflow pipe, 2... Treated water outflow pipe, 6...
Solid particles, 4... Fluidized bed biological treatment tank, 6... Circulation section, 7... Separation section, 8... Air introduction pipe, 9... Air lift pipe, 10... Sample collection pump, 11...
sv automatic measuring device, 12... cylinder, 16...
SV automatic measurement unit), 14...Sequence controller? , 15... Comparison calculator, 16... Adjuster, 17
...Extraction pump, 18...Microorganism stripping device. Patent applicant: Patent attorney representing Ebara Infilco Co., Ltd.
Masayuki Takagi, Patent Attorney 1) Minoru, Patent Attorney Takao Maruyama

Claims (1)

[Claims] 1. A fluidized bed in which solid particles are suspended as microbial carriers in a tank, and the solid particles are circulated and fluidized by agitating gas through an air lift pipe installed in the tank. In the formed biological treatment device, a sample of the mixed liquid in the tank is taken and the SV value, that is, is measured, and the solid particles in the tank are extracted and the microbial film is separated by φ] so that the SV value is within the appropriate range. A method for controlling a fluidized bed biological treatment device, characterized in that the fluidized bed is then returned to a tank. 2. In a biological treatment device in which solid particles are suspended as microbial carriers in a tank, and a fluidized bed is formed in which the solid particles are circulated and fluidized by agitating gas through an air lift pipe arranged in the tank. , the mixed liquid in the tank is drawn out and the above-mentioned S
It is equipped with an SV automatic measurement device that measures the V value, and a comparison calculator that compares and calculates the SV measurement value of the vsv automatic measurement device and the Sv setting value. 1. A control device for a fluidized bed biological treatment device, comprising a microbial membrane peeling device that is activated when a set value is exceeded. 3. The S automatic measurement device is equipped with a sample collection pump, and has a built-in light transmission type SV automatic unit,
3. The control device for a fluidized bed biological treatment apparatus according to claim 2, further comprising a controller for periodically interlocking said unit and said sample collection pump.