JPS6034794A - Biological treating apparatus of organic waste - Google Patents

Abstract

PURPOSE:To perform biological treatment with low energy cost and high treating efficiency by providing a circulation pump and a means for changing circulation amt. in circulation line intermittently and operating a fluidizing bed with low rate of development in the normal state and with high rate of development intermittently. CONSTITUTION:Organic waste is allowed to stay in an anaerobic tank 1 for a fixed time and an upward flow speed is given to the liquid in the tank by circulating the liquid through a circulation line 5. Carrier particles are develped to form fluidized bed 2, and the sludge generated by the proliferation of anaerobic microorganisms is held in the fluidized bed to cause decomposition of the organic substances. In this state, the operation is performed in the normal state with low rate of development of the fluidizd bed 2 to maintain the boundary face of the fluidized bed at low level 2a and the operation with high rate of development is performed intermittently to elevate the boundary face of the fluidized bed to high level 2b. In order to change the rate of divelopment, either one of the circulation pump 6 or 7 is driven when the rate of development is low, and both of the pumps are driven when the rate of development is high.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for biological treatment of organic waste, particularly an aerobic or anaerobic treatment apparatus using a fluidized bed tank containing biological carrier particles.

A treatment method is used in which organic waste such as sewage sludge and human waste is retained in a biological treatment tank and subjected to aerobic or anaerobic digestion to decompose the organic matter. Among these methods, anaerobic treatment decomposes organic matter in an anaerobic state by the action of anaerobic bacteria, and unlike aerobic treatment, it does not require an aeration tank, so the power cost is low, but the treatment time is long and There was a problem that the device became larger. - In order to solve these problems, an anaerobic treatment device has been proposed that uses a biological carrier to form a fluidized bed and holds the sludge in the fluidized bed to increase treatment efficiency. Even in aerobic treatment, the fluidized bed method is still used because it allows high sludge concentration and has excellent treatment effects.

In such a fluidized bed method, it is necessary to allow as many microorganisms (sludge) as possible to adhere and grow on the surface of the fluidized carrier and to maintain uniform mixing with organic waste. It is necessary to provide a good flow state as a development rate of %.

However, in order to maintain such a high retention rate, it is necessary to circulate a large amount of liquid and provide a high upward flow velocity, which increases power costs. There was a problem that the significance of anaerobic treatment was lost.

This invention is intended to improve the above-mentioned problems, and by operating the fluidized bed normally at a low expansion rate and intermittently at a high expansion rate, the power cost can be reduced. The purpose of the present invention is to provide a biological treatment device for organic waste that can perform biological treatment with high treatment efficiency.

This invention comprises a biological treatment tank in which a fluidized bed of biological carrier particles is formed, a circulation system path for circulating a liquid so as to give an upward flow velocity to the biological treatment tank, and a circulation pump provided in this circulation system path. , a means for intermittently changing the amount of circulating water in the circulation system path, and the fluidized bed is normally operated at a low expansion rate and is intermittently operated at a high expansion rate of ψ. This is a biological treatment device for organic waste.

When biological treatment is performed using a fluidized bed method, the development rate is 60 to 7.
If it is set to 0%, a good fluidity state can be obtained, but if the expansion rate is operated at a lower rate, for example, 10-30%, there will be no large movement or mixing of the carrier particles in the tank, and the processing efficiency will drop significantly. .

When observing the state of the fluidized bed at this time, it was found that the entire bed was fluidized at first, but because the flow of the carrier particles was slow,
It was found that as the biolayer grows, particles that become heavier settle to the lower layer, forming a layer that does not fluidize, cutting off contact between the biolayer and organic matter and reducing treatment efficiency. Therefore, when the upward flow rate is increased intermittently to reach a deployment rate of 60 to 70%, mixing and agitation will proceed again, the excess biofilm will be peeled off, and fluidization will be uniform. It was found that a uniform fluidized state could be maintained for a long period of time with a low development rate.Therefore, in the present invention, a means was provided to intermittently change the amount of water in the liquid circulation path, and the fluidized bed was normally operated at a low development rate. The system is operated intermittently at a high development rate, thereby keeping the fluidized bed in a uniform fluid state, ensuring good contact between the biological layer and organic matter, and maintaining high treatment efficiency with low power costs.

The organic waste to be treated in the present invention includes sewage sludge, human waste, excess activated sludge, organic waste liquid, etc., but the concentration, composition, etc. thereof are not limited, and the organic waste may contain solid matter.

Hereinafter, the present invention will be explained based on the drawings, taking the case of anaerobic treatment as an example. 1 and 2 are system diagrams each showing another embodiment of the present invention.

- In FIG. 1, 1 is an anaerobic tank with a closed structure, the inside of which is filled with biological carrier particles to form a fluidized bed 2, to which a raw water pipe 6 and a treated water pipe 4 are connected. A circulation line 5 is provided in the upper part of the anaerobic tank 1 to circulate the liquid in the tank from above the fluidized bed 2 to the bottom of the tank, and a plurality of circulation pumps 6 and 7 are arranged in parallel along the way. It is provided.

The raw water pipe 6 is connected to the circulation line 5, and the treated water pipe 4 is connected above the connection part of the circulation line 5. A gas chamber 8 is formed in the upper part of the anaerobic tank 1, and a gas exhaust pipe 9 is connected to the top of the gas chamber 8. The anaerobic tank 1 is provided with heating means, temperature detection means, pressure detection means, etc., and each pipe line is provided with valves, etc., but illustration thereof is omitted. As biological carrier particles,
Conventional materials such as sand, zeolite, and activated carbon can be used.

In the above configuration, the anaerobic tank 1 is filled with biological carrier particles, organic waste is supplied from the raw water pipe 6, and the circulation pump 6 or 7 is driven to send the liquid at the top of the tank through the circulation path 5 to the bottom of the tank. The carrier particles are circulated and passed through the anaerobic tank 1 in an upward flow to fluidize the carrier particles, forming a fluidized bed 2 to perform anaerobic treatment. At this time, heating is performed by a heating means (not shown) to cause anaerobic bacteria to proliferate and adhere to the carrier particles, and the organic matter is brought into contact with the carrier particles to be decomposed.

The decomposition of organic matter in anaerobic treatment involves multiple steps.
It can be roughly divided into a stage in which a polymeric substance or a complex organic substance is hydrolyzed into a simple compound, a stage in which a lower organic acid is produced from a simple compound, and a stage in which methane is produced from a lower organic acid. The first two stages are called the acidogenic phase and are caused by facultative anaerobes, and the final stage is called the methanogenic phase and is caused by the action of obligate anaerobes, methanogens.

The biological treatment device of the present invention can be used as a treatment device for any of the above production phases, and can also be used as a treatment device for a mixed phase of both. When used as a reservoir for the acid-producing phase, the attached organisms are mainly acid-producing bacteria, and little methane is generated. On the other hand, when it is used for the methanogenic phase, the attached organisms are mainly methanogenic bacteria, and a large amount of methane is generated. In the case of a mixed phase, both types of bacteria adhere, and acid production and methane production occur in parallel.

In either case, the organic waste is allowed to remain in the anaerobic tank 1 for a certain period of time, and when the liquid is circulated through the circulation system path 5 to give an upward flow rate in the tank, the carrier particles are expanded and the fluidized bed 2 is expanded. The sludge that forms and is produced by the growth of anaerobic microorganisms is retained in a fluidized bed where organic matter decomposition occurs.

In the present invention, the expansion rate of the fluidized bed 2 at this time is normally operated at a low expansion rate to maintain the interface of the fluidized bed 2 at a low interface 2a, and intermittently operated at a high expansion rate to maintain the fluidized bed 2 at a low expansion rate. 2 is raised to the high interface 2b. In this embodiment, the means for changing the expansion rate is carried out by controlling the number of circulating pumps 6.7 in operation. In other words, when the deployment rate is low, the circulation pump 6.7
Operate either one, or both when the deployment rate is high.

The actual value of both expansion rates depends on the type and size of carrier particles,
The optimal value can be selected depending on the type and amount of organic waste, the switching sequence of the development rate, etc., but the low development rate is the minimum development rate necessary to maintain the fluidized bed, and is generally 10 to 30%. The high development rate is a development rate suitable for loosening the fluidized bed and peeling off excess biofilm, and is generally 60 to 70%.

The optimum deployment rate switching sequence can be selected depending on the various conditions mentioned above, but for example, one hour a day, etc.
This can be done at a rate of 5 minutes per hour. The time and frequency of operating at a high development rate is to loosen the non-flowing part that was generated when operating at a low development rate and peel off the excess biofouling film. If the frequency is high, the operating time for one operation may be short.

When operating at a low development rate, a biofilm adheres to the surface of the carrier particles and settles, forming a non-flowing part, but this non-flowing part and the inside of the thick biofilm are no longer in contact with organic matter. Therefore, it no longer participates in anaerobic decomposition, reducing processability. When the expansion rate is increased from this state, the whole becomes fluid again and the agitation becomes vigorous, which loosens the bonded parts and peels off the thick biofilm, turning the whole into light particles. Therefore, even if the expansion rate is lowered, the whole can be maintained in a fluid state, and the processing efficiency can be maintained at a high level.

Methane gas generated by the anaerobic treatment is collected in the gas chamber 8 and discharged from the gas exhaust pipe 9. Further, a part of the liquid in the tank is discharged from the treated water pipe 4 as treated water.

In the embodiment shown in FIG. 2, one circulation pump with a variable discharge amount is provided in the circulation system path 5, and an interface level meter 10a,
Based on the signal from the controller 10b, the discharge amount is controlled by the controller 11 so as to maintain the interface 2a or the high interface 2b.

The other configurations are the same as in FIG. 1.

In the above configuration, according to a predetermined sequence, the discharge amount of the circulation pump 6 is normally controlled to operate at a low development rate so that the interface level meter 10a detects the low interface 2a, and the interface level meter is intermittently operated. The circulation pump 6 is operated at a high expansion rate by controlling the discharge amount of the circulation pump 6 so that the high interface 2b is detected by the pump 10b. With such a configuration, the expansion rate can be controlled accurately.

Other operations are the same as in the case of FIG.

The means for controlling the flow rate is an interface level meter 10a.
, 10b, it may be controlled by a flow meter or the like.

When using the present invention as an aerobic treatment, the above-mentioned anaerobic tank 1
All you have to do is keep it in an aerobic state. For this purpose, the tank is not closed, but is open, and oxygen or air is supplied in the middle of the circulation path 5, or air or oxygen is diffused from the bottom of the tank.

As explained above, according to the present invention, a means is provided to intermittently change the flow rate of the circulation system in the reservoir forming the fluidized bed, so that the fluidized bed is normally operated at a low expansion rate, and the fluidized bed is operated intermittently. Since the system is operated at a high development rate, the fluidized bed can be maintained in a fluidized state at all times, which has the effect of reducing power costs and allowing biological treatment to be performed with high treatment efficiency.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are system diagrams each showing another embodiment of the present invention. In each figure, the same reference numerals indicate the same or equivalent parts, 1 is an anaerobic tank, 2 is a fluidized bed, 5 is a circulation system path, 6 and 7 are circulation pumps, 10a and 10b are interface level meters, and 11 is a controller. . Figure 1 Figure 2

Claims (1)

[Claims] (11) A biological treatment tank in which a fluidized bed of biological carrier particles is formed;
a circulation system path that circulates the liquid so as to give an upward flow velocity to the biological treatment tank; a circulation pump provided in the circulation system path;
and means for intermittently changing the amount of circulating water in the circulation system, wherein the fluidized bed is normally operated at a low development rate and intermittently operated at a high development rate. Biological waste treatment equipment. (2) The organic waste biological treatment apparatus according to claim 1, wherein the means for intermittently changing the amount of circulating water is changing the number of operating circulation pumps connected in parallel. (3) The organic waste biological treatment apparatus according to claim 1, wherein the means for intermittently changing the amount of circulating water changes the discharge amount of the circulation pump. (4) The organic waste biological treatment apparatus according to claim 6, wherein the discharge amount of the pump is controlled by an interface detection means of the fluidized bed. .