JPH0128867Y2 - - Google Patents

Description

[Detailed description of the invention] This invention suspends granular solids in a tank as a carrier for microbial attachment, and circulates the granular solids in the tank while stirring the gas using an air lift tube installed in the tank. This invention relates to a biological treatment device for fluidized wastewater.

Recently, various biofilm-type sewage treatment systems have been put into practical use that use tube catalytic oxidation, rotating disk method, granular solid fluidized bed method, etc. to solve the bulking phenomenon and complexity of maintenance in the activated sludge method. has been done. Among these methods, microorganisms are attached to the surface of granular solids suspended in a tank, and the granular solids are circulated and flowed in the tank while gas agitation is carried out through an air lift pipe installed in the tank, and the solids come into contact with wastewater. Compared to other biofilm methods, the granular solid fluidized bed method, which removes pollutants from wastewater, allows for a much larger surface area of the granular solids for microorganisms to adhere to, so it is possible to collect a large amount of microorganisms in the tank. It is attracting attention because it has many advantages, such as the ability to hold solids, and because the granular solids circulate and flow within the tank, problems such as clogging and partial anaerobic formation do not occur.

In this granular solid fluidized bed method, materials such as sand, anthracite, activated carbon, zeolite, and plastic spheres are suitable for attaching microorganisms, and particles with specific gravity and particles suitable for smooth circulation and fluidization within the tank are used. A granular solid with a certain diameter is used, but usually the particle size is 0.1 to
Sand of about 0.4 mm is often used, and the amount of such granular solids added to the tank is appropriately determined depending on the operating conditions, but usually 5 to 20% of the tank capacity is added.

In addition, the air lift tube has an air introduction tube connected to its lower part, and due to the air lift action of the air blown into the tube, granular solids circulate inside and outside the air lift tube, and the lower part of the tank absorbs this circulating flow. To ensure smoothness, it is usually sloped so that the cross-sectional area decreases downward.

A part or the entire circumference above the tank in which the air lift pipe is installed is divided into a circulation part and a separation part by a partition wall whose upper end is above the water surface and whose lower end is below the water surface. A portion of the liquid separates granular solids while rising through this separation section, and is taken out from above as effluent water. Furthermore, this effluent is usually sent to a coagulation sedimentation, sand filter, etc. as a post-treatment device, and undergoes treatment such as removing SS, BOD, and COD from the effluent, and becomes the final treated water.

Incidentally, although such a granular solid fluidized bed method has many advantages, it relies only on the airlift action of the air blown into the airlift tube to circulate the granular solid, so it is difficult to change the air blowing conditions. Or, when air blowing is stopped due to repairs, power outages, etc., granular solids in the tank will settle on the bottom of the tank, and the surface of the deposited particles will usually be above the lower end of the air lift pipe suction, and there will be a gap between the lower end of the suction, the lower part of the tank, and the air lift pipe. This will close the gap.

When restarting, it is necessary to fluidize the deposited granular solids again, but simply blowing in air does not provide enough liquid flow rate to fluidize the deposited particles, making startup impossible. This is a fatal situation for.

For this purpose, in the conventional method, these deposited particles are fluidized so that they can be transported by air lift.
Generally, a sufficient amount of startup water is blown from the bottom of the tank to fluidize the sedimented particles, and once the sedimented particles are expanded and fluidized, air injection is started and restarted. Various ideas have been made regarding starting water injection methods and injection structures.

However, these methods first require the use of a large amount of water for startup, and require equipment to secure this amount of water. In other words, if this water is obtained externally, a large-scale water tank is required. And if this is collected from the upper part of the tank,
There are drawbacks such as the suction of particles in the tank, which can cause blockages in the starting water injection parts (nozzles, distributors, water pipes, etc.).
It is difficult to uniformly fluidize the particles, which are densely deposited with microorganisms, throughout the tank, and in order to achieve reliable fluidization, many nozzles and distributors are used, and starting water spray is used. The structure was complicated and uneconomical, as it required a high-pressure, high-flow water pump.

The purpose of the present invention is to provide a new fluidized bed biological treatment apparatus that eliminates the troubles that tend to occur with conventional apparatuses and allows for simple and reliable restarting.

The present invention has a tank that has a raw water inlet and a treated water outlet and contains granular solids for adhering to microorganisms.
A circulation part and a separation part are defined by a partition wall having an upper end above the water surface and a lower end separated from the tank bottom, and into the circulation part, the upper end is below the water surface and the lower end is almost near the tank bottom, and air is introduced near the lower end. The present invention is a fluidized bed biological treatment apparatus equipped with an airlift tube in which pipes are connected, and is characterized in that at least the lower end of the airlift tube is movable up and down.

To explain one embodiment of the present invention with reference to the drawings, the first illustrated example shows a state in which granular solids are deposited in the tank, and the raw water inflow pipe 1 is opened and the treated water outlet 2 is opened upward. In the tank 4 containing the granular solids 3 for adhesion of microorganisms, a circulation part 6 and a separation part 7 for the granular solids 2 are separated by a partition wall 5 whose upper end is above the water surface and whose lower end is separated from the tank bottom. Compartments are formed. An air lift pipe 8 having an upper end below the water surface and a lower end spaced apart from the tank bottom is disposed approximately in the vicinity of the center of the circulation section 6, and an air introduction pipe 9 is open-connected to the lower part of the air lift pipe 8.

Further, at least the lower end of the air lift tube 8 is made to be able to be raised and lowered, but the entire air lift tube 8 may be made to be able to be raised and lowered below the water surface, or it may be structured as shown in the illustrated example. That is, as shown in the illustrated example, the air lift pipe 8 has a double structure inside and outside, and either the outside or the outside is fixed, and the elevator pipe 8'' is slidably fitted into the fixed pipe 8', and the elevator pipe 8'' is screwed into a screw rod. 10, and is slid up and down on the fixed tube 8' using a handle 11 outside the tank or another power source (not shown).

Further, as in the second illustrated example, the elevator pipe 8'' may have a double pipe structure in which a large diameter pipe is combined at the lower end.

In addition, since the air introduction pipe 9 is open-connected to the lower part of the air lift pipe 8, it is convenient to make at least a part of it a flexible pipe 12 so as to follow the rise and fall of the air lift pipe.

Next, to explain its effect, during normal processing operation, the tank liquid in which the granular solids 3 are suspended is caused by the air lift effect of the air blown into the air lift tube 8 downward from the air introduction tube 9. A circulating flow state is formed in which air flows into the air lift tube 8 from the lower end thereof, is discharged from the upper end, descends into the circulation section 6, and then flows back into the air lift tube 8 from the lower end.
The sewage introduced into the tank 4 from the raw water inflow pipe 1 is circulated through the tank as described above, and the aerobic action of the microorganisms attached to the surface of the granular solids 3 causes the sewage to become The pollutant components are decomposed and removed, and a part of this circulating liquid passes through the lower end of the partition wall 5 and flows into the separation section 7, where the granular solids 3 are sedimented and separated, and are discharged from the outflow section 2 to the outside of the tank as treated water. leak.

Now, if the blowing of air from the air introduction pipe 9 is stopped for some reason, the granular solids 3 in the tank 4 will be deposited on the bottom of the tank as shown in the first figure, and the lower end of the air lift pipe 8 and the air lift pipe 8 will be deposited. The space between the tank and the tank wall is blocked. In order to circulate and flow the deposited granular solids 3 again, the entire air lift tube 8 must be lifted upwards under the water surface, or the lifting tube 8'' in the illustrated example can be pulled up to remove the deposited granular solids 3 from the lower end of the air lift tube 8. Set it at a position where there is an appropriate distance between the air introduction pipe 9 and the interface.
When air is blown in, particles near the interface circulate inside and outside the air lift tube 8 due to the water flow generated near the interface. Therefore, by gradually lowering the lower end of the air lift tube 8, more and more of the deposited particles will be sucked into the air lift tube 8 and circulated, eventually making it possible to circulate and flow all the deposited particles.

In addition, as shown in Fig. 1, if a starting water pipe 13 is attached near the bottom of the tank 4 and used in conjunction with the future starting water injection, effective starting can be achieved in a shorter time. .

As described above, according to the present invention, the simple structure in which the lower end of the air lift tube can be raised and lowered allows the fluidized bed biological treatment equipment to be started easily and reliably, thereby saving startup water. , which enables efficient and reliable operation.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.
FIG. 2 is a perspective view showing an example of the lower end of the air lift tube. DESCRIPTION OF SYMBOLS 1... Raw water inflow pipe, 2... Outflow pipe, 3... Granular solid, 4... Tank, 5... Partition wall, 6... Circulation part, 7
... Separation section, 8 ... Air lift pipe, 8' ... Fixed pipe, 8'' ... Lifting pipe, 9 ... Air introduction pipe, 12
... Flexible pipe, 13 ... Starting water sprinkler pipe.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. In a tank having a raw water inlet and a treated water outlet and containing granular solids for adhesion of microorganisms, circulation is carried out through a partition whose upper end is above the water surface and whose lower end is separated from the bottom of the tank. The fluidized bed biological treatment apparatus is provided with an air lift pipe having an upper end below the water surface and a lower end substantially near the bottom of the tank, and an air inlet pipe connected to the lower end near the lower end. A fluidized bed biological treatment apparatus characterized in that at least the lower end of the air lift tube is movable up and down. 2. The fluidized bed biological treatment apparatus according to claim 1, wherein the air lift tube has a double structure and is slidable relative to each other.