JPH022473Y2 - - Google Patents

Description

[Detailed description of the invention] "Industrial application field" This invention is a fluidized bed wastewater treatment system that biologically treats wastewater by suspending solid particles (microbial carriers) to which microorganisms are attached or encapsulated in wastewater. It relates to a processing device.

"Conventional technology" Traditionally, wastewater treatment methods are more expensive than biofilm methods such as activated sludge method, contact aeration method, and rotating disk method.
The fluidized bed method is attracting attention because it has the advantage of reducing the BOD volume load and making the equipment more compact. As is well known, in this fluidized bed method, it is essential to continuously use solid particles in a fluidized suspension state in a treatment tank.

As a fluidized bed type wastewater treatment apparatus used in such a fluidized bed method, one having the structure shown in FIG. 2 is conventionally known. As shown in the figure, this processing apparatus consists of a fluidization tank 1 and a settling tank 2. The fluidized tank 1 has a draft tube 3 in its center.
is erected, an overflow weir 4 is provided at the top, and a circular column 5 for separating sludge and solid particles is provided between the weir 4 and the tube 3. An air diffuser 7 connected to an electric blower 6 is provided at the bottom of the draft tube 3 . This fluidized tank 1
The wastewater is circulated in the direction of the arrow in the figure by the upward movement of air blown into the bottom of the tank from the air diffuser 7. As the wastewater circulates, solid particles are also circulated and brought into good contact with the wastewater, thereby purifying the wastewater. After the solid particles are removed from the treated wastewater in the solid separation section 8 between the overflow weir 4 and the sludge separation column 5, it flows over the overflow weir 4 and becomes effluent into the settling tank 2. It is starting to be sent.

In this fluidized bed type wastewater treatment equipment, if the amount of particles filled inside the fluidized tank 1 is increased, the total surface area of the particles increases accordingly, and the amount of microorganisms retained in the tank increases, which has the advantage of increasing the reaction rate of waste removal. be.

``Problems that the invention attempts to solve'' By the way, conventional fluidized bed wastewater treatment equipment has
Although it has the above advantages, it also has the following problems.

In other words, when the flow of particles stops due to equipment shutdown, power outage, or slight fluctuations in operating conditions such as fluctuations in blowing air pressure, solid particles are deposited at the bottom of the tank, and the surface of the deposited particles is usually in the draft tube. 3, and covers and closes the lower end of the draft tube 3, the air diffuser 7, and the lower part of the tank. In such a case, it is necessary to fluidize the deposited solid particles again in order to restore the normal startup state, but simply blowing air from the air diffuser 7 will not reach the liquid flow rate that is sufficient to fluidize the deposited particles. It is difficult to obtain this, and it has the disadvantage of causing a fatal situation where it cannot be started.

In response to this, the following three structures have been proposed as processing device structures for normal startup.

(i) A structure that discharges pressurized water from the bottom of the fluidized tank.

(ii) The draft tube has a double structure, and when the flow stops and particles are deposited, the lower end of the draft tube is pulled upwards and gradually lowered while operating.

(iii) A structure in which an aeration device is installed at the bottom around the draft tube in the fluidized tank to provide aeration.

However, each of these processing apparatuses has the following problems and is not suitable for practical use.

Problems with the device (i) (a) A large amount of starting water is required, and if that water is obtained from outside the system, a large water storage tank is required.

(b) If starting water is collected from the upper part of the fluidized tank, starting water equipment such as nozzles and discharge devices will be clogged by particles in the tank.

(c) A pump with high pressure and high water flow rate is required as a pump for discharging water for startup.

Problems with the device (ii) (a) The double sliding structure of the draft tube is complicated, increasing equipment costs.

(b) It is difficult to adjust the lower end of the draft tube when gradually lowering it.

(c) When many particles are suspended in a fluidized tank,
Even if part of the upper part of the deposited particles becomes fluidized due to the rise of the draft tube, before the entire part becomes fluidized, it descends around the outer circumference of the draft tube and is deposited outside the draft tube, causing the entire flow inside the tank to become fluidized. Circulation cannot be easily restored.

Problem with the device (iii): If the tank is filled with many particles to increase the amount of microorganisms retained in the tank, even if only the particles at the bottom around the draft tube are floated, the flow of particles will stop. Due to the large number of particles deposited in the draft tube during this period, it is not easy to return to the fluid circulation state.

Further, a common problem of the three devices mentioned above is that they do not have a structure that detects the stoppage of particle flow and automatically takes a recovery means.

"Means for Solving the Problems" The inventor of the present invention has conducted extensive research in order to solve the above-mentioned conventional problems, and has come to the following knowledge.

That is, it has been found that when the waste liquid flow circulation is stopped due to a power outage or the like and particles are deposited, the particles are deposited as shown in FIG. 3, regardless of the operating conditions before the stop. In other words, draft tube 3
The particles are deposited on the lower outer peripheral portion (portion A in the figure), and the particles are also deposited in the draft tube 3 to a position higher than the interface of the deposited particles in the outer peripheral portion (portion B in the figure). In this state, no matter how much air is blown from the conventional air diffuser 7, the air will be blocked by the accumulated particles in the B part of the draft tube 3 and will escape to the outer periphery of the draft tube 3, causing the liquid in the tank to No circular flow occurs. On the other hand, even if an air diffuser is newly installed at the lower part of the draft tube 3 and air is blown into it, no flow occurs, and even if a new air diffuser is installed at the lower outer circumference of the draft tube 3 and air is blown into it, no flow occurs. It was found that there was no effect, and that the flow of the liquid in the tank occurred only when both of these were diffused at the same time.

This idea was made based on the above knowledge, and in addition to providing an aeration device in the lower half of the draft tube of the fluidization tank and the outer circumference of the lower part of the draft tube, the sludge concentration was A flow stop sensing device such as a meter, a current meter, or a sludge interface meter is attached, and both of the aeration devices are simultaneously driven based on the output signal of this sensing device. The installation position of the air diffuser in the draft tube depends on the amount of particles in the tank, but it must be located in the lower half of the draft tube, from the upper part near the bottom end of the draft tube to the middle of the draft tube. is described as the lower half part.

"Operation" According to the above configuration, the sensing device senses the stoppage of the flow of the liquid in the tank, and the sensing device simultaneously drives and diffuses the air diffusers inside and outside the lower part of the draft tube. Then,
The air from the air diffuser in the draft tube floats and floats the accumulated particles in section B in FIG. 3, and the air diffuser outside the draft tube temporarily levitates and loosens the accumulated particles in section A. Furthermore, since these events occur simultaneously, the fluid circulation state within the tank is quickly restored.

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment FIG. 1 shows an embodiment of the present invention. In the figure, parts common to FIGS. 1 and 2 are given the same reference numerals to simplify the explanation. In the figure, code 10
a and 10b each indicate an air diffuser installed at the outer circumferential portion of the lower part of the draft tube 3, and reference numeral 11
1 shows an air diffuser installed in the lower half of the draft tube 3. The air diffusers 10a and 10b are connected to the blower 6 via an electromagnetic on-off valve 12, and the air diffuser 11 is also connected to the blower 6 via an electromagnetic on-off valve 12. Further, a sludge concentration meter (flow stop sensing device) 14 is attached to the upper part of the aeration device 10a, and the sludge concentration meter 14 can simultaneously output operation signals to the electromagnetic on-off valves 12 and 13. It is composed of In the above configuration, the sludge concentration meter 14 is installed at a height such that it is within the layer of accumulated particles when the flow is stopped, and is configured to issue an activation signal to the electromagnetic on-off valves 12 and 13 to open only when the particles are accumulated. It is set to .

According to the above configuration, when the flow of the liquid in the tank stops for some reason and particles are deposited, the sludge concentration meter 14 senses this state, issues an activation signal, and activates the electromagnetic on-off valves 12 and 13. Open.
As a result, the air diffuser 11 inside the draft tube 3
The air blown from the draft tube 3 floats the accumulated particles in the draft tube 3.
The outside air diffusers 10a and 10b temporarily levitate and loosen the accumulated particles on the lower outer peripheral portion of the draft tube 3. Since these actions occur simultaneously, the fluid circulation state within the tank is quickly restored. In addition, in such a wastewater treatment device, in order to increase the absorption efficiency of oxygen in the tank, it is necessary to secure a somewhat large aeration area of the aeration device, but in conventional devices, there is no airflow inside the draft tube 3 that obstructs the flow. It is physically difficult to provide a large air diffuser. However, according to the configuration of this invention, as a side effect, a large amount of fine bubbles can be generated with the same volume as before, without having to secure a large volume for aeration, and the intake efficiency can be greatly improved. It is possible to increase it.

In the above configuration, when the flow state in the tank returns to normal, the sludge concentration meter 14 issues a closing signal to close the electromagnetic on-off valves 12 and 13, or a timer mechanism closes them to return to normal operation. It has been set. Further, the appropriate installation position of the air diffuser 11 within the draft tube 3 is within a range of 1/2 of the length of the draft tube 3 from above near the lower end of the draft tube 3. Furthermore, in the above embodiment, a sludge concentration meter was used as a flow stoppage sensing device.
In addition, flow meters and sludge interface meters can also be used. When using a current meter, the installation method differs depending on its type, but it may be installed anywhere as long as it does not interfere with the flow. When using a sludge interface meter, install it above the particle layer interface so that it can sense the interface in the accumulated state. Furthermore,
The air diffusers provided on the lower outer circumferential portion of the draft tube 3 may be two individual air diffusers as in the above embodiment, or one ring-shaped air diffuser may be provided.

"Effects of the Invention" As explained above, the fluidized bed wastewater treatment device according to the present invention is provided with air diffusers in the lower half of the draft tube of the fluidized tank and in the outer circumference of the lower part of the draft tube. A flow stop sensing device such as a sludge concentration meter, flow rate meter, or sludge interface meter is installed at an appropriate location on the outer periphery of the lower part of the draft tube, and both of the above air diffusers are simultaneously driven based on the output signal of this sensing device. be.

Therefore, according to the present invention, the sensing device detects the stoppage of the flow of the liquid in the tank, and the sensing device simultaneously drives and diffuses the air diffusers inside and outside the lower part of the draft tube, thereby reducing the air flow from the air diffusers inside the draft tube. The system floats the accumulated particles inside the draft tube, and the air diffuser outside the draft tube temporarily levitates and loosens the accumulated particles on the outer periphery of the lower part of the draft tube. The fluid circulation state can be quickly restored.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the present invention. Fig. 2 is a block diagram of a conventional fluidized bed wastewater treatment apparatus, and Fig. 3 is a block diagram of a conventional fluidized bed wastewater treatment apparatus. FIG. 2 is a state diagram when the flow of solid particles in a fluidized tank stops and the particles accumulate in a fluidized bed wastewater treatment device. 1... Fluidization tank, 2... Sedimentation tank, 3... Draft tube, 6... Blower, 7, 10a, 10b,
11... Diffuser, 12, 13... Solenoid shut-off valve,
14...Sludge concentration meter (flow stoppage sensing device).

Claims (1)

[Claims for Utility Model Registration] Microorganisms are attached to or encapsulated in wastewater that flows into a fluidized fluid tank that has a cylindrical draft tube inside and a diffuser that blows air into the tank below the draft tube. In a fluidized bed wastewater treatment device that biologically treats wastewater by suspending solid particles, an air diffuser is installed in the lower half of the draft tube and the lower outer circumference of the draft tube. A fluidized bed wastewater treatment apparatus, characterized in that a flow stop sensing device is attached to a predetermined position of the sensor, and both of the aeration devices are simultaneously driven based on an output signal of the sensing device.