JPS59193195A - Fixed bed type sewage cleaning up tank - Google Patents

Abstract

PURPOSE:To prevent the rise in a water level owing to progression of clogging by providing a detector for the watr level in a tank and a device for diffusing gas into an outflow pipe and controlling the flow rate of said gas, and changing the flow rate of the gas into a water flow pipe according to a change in the water level. CONSTITUTION:When the operation of a cleaning up tank is continuously performed, the clogging in a packing material 3 is progressed by thickening of biological membrane and the water level in the tank rises graudally until the level arrives at a preset position, then a water level controller constituted of the 2nd air diffuser 15, a flow rate regulating valve 16 and a float 17 operates to maintain the water level. More specifically, the 2nd air diffuser 15 has the function of an air lift pump together with an outflow pipe 6, and the suction power thereof increases or decreases according to the flow rate of the gas diffused from the diffuser 15. When the water level rises to lift the float 17, the valve 16 is opened and the gas is discharged from the diffuser 15 to suck and discharge treated water 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] This invention relates to water level control in a fixed bed type sewage purification device that purifies sewage through the action of microorganisms grown on the surface of a filler.

[Prior art and its problems]

The fixed bed method has been well known as one of the methods for purifying wastewater using the action of microorganisms.

The fixed bed method uses corrugated plastic plates in a sealed tank.
A filling material formed of a net or the like is housed and sewage is allowed to flow into it, and the sewage is agitated using a mechanical stirring device or an air lift using aeration, and brought into circulation contact with microorganisms that have grown on the surface of the filling material. This is to purify wastewater. Various types of equipment are used for this type of treatment, depending on the stirring method and the location of the filler, but the most commonly used equipment is one that is installed in the center of the tank. It has a stirring section and a filler is installed between the inner wall of the tank and the stirring section, and its vertical cross section is shown in FIG. 1.

In FIG. 1, the upper opening of a tank 1 is sealed with a cover 2, and a filling material 3 made of corrugated plastic sheet, net, etc. is placed inside along the side wall. A stirring section 4 is formed in the center. An inflow pipe 5 is provided passing through the upper part of the side wall of the septic tank 1, and an outflow pipe 6 is provided at a position slightly lower than the inflow pipe 5 and higher than the top surface of the filler 3 on the side wall opposite to the inflow pipe 5. is provided.

One end of the outflow pipe 6 passes through the filling material 3 in the tank from the top to the bottom of the filling material 3, and the other end of the outflow side is connected to the gas-liquid separator 7 outside the tank. has been done. cover 2
A pipe 8 that penetrates the tank is connected to the inlet side of a first compressor 9 installed outside the tank, and a pipe 8a connected to the outlet side of the compressor 9 penetrates the cover 2 and connects the tank agitation section 4. The tip is connected to the air diffuser 10 near the bottom of the tank.

Further, a backwashing air diffuser 11 is provided inside the tank by penetrating the tank side wall near the bottom of the tank, and this backwashing air diffuser 11 is connected to a second compressor 12 located outside the tank. Further, a sludge drain pipe 13 is attached to the bottom of the tank, and a sludge drain valve 14 is provided at the tip thereof.

To explain the process of treating sewage in the fixed bed type sewage septic tank having the above-described structure, first, sewage F flows into the tank through the inflow pipe 5 and is stored therein. Anaerobic gas mainly composed of methane gas generated in the septic tank 1 is sucked into the pipe 8 by the action of the first compressor 9, sent to the pipe 8a, and sent to the stirring section 4 from the aeration device 10 at the tip. . The sewage is agitated by carbon and is purified by coming into contact with microorganisms that have adhered to and grown on the surface of the filler 3 to form a biofilm. The purified water passes through an outflow pipe 6 piped through the filling material 3 from the lower surface of the filling material 3, and flows out into the gas-liquid separator 7 as treated water T.

If this kind of treatment is carried out continuously for several months,
The thickness of the biofilm increases until the biofilm itself becomes a filler3.
0 It can no longer be supported on the surface and peels off, contaminating the treated water T and causing deterioration of water quality. Furthermore, since the biofilm grows in the gaps in the filler 3, the gaps gradually become smaller and become clogged, which impairs the circulation of water in the tank and deteriorates the purification effect. As a countermeasure against this problem, backwashing should be carried out periodically. For this purpose, the second compressor 12 is operated to blow air from the backwashing air diffuser 11 provided below the filler 3 in the tank. As a result, the air bubbles pass through the gaps in the filler 3 and peel off the thickened biofilm. The separated biofilm is deposited on the bottom of the septic tank 2 after the second compressor 12 is stopped, so the sludge valve 1
When the valve 4 is opened, the sludge is discharged to the outside of the tank through the drainage pipe 13. Note that the first compressor 9 is not operated during backwashing and sludge removal. The processing steps above are for a normal case, but in a conventional sewage septic tank, as the filler 3 becomes clogged, When there is a height difference between the treated water discharge position and the water level in the tank, the water level in the septic tank 1 rises, and the vertical dimension difference between the inflow position of sewage F and the outflow position of treated water T is small, the treated water T flows back through the inflow pipe 5. There was a drawback. In a normal fixed-bed sewage purification process, multiple fixed-bed sewage septic tanks are connected in series, so the above-mentioned backflow phenomenon causes the water level to rise in the tank preceding the clogged tank. Therefore, it is impossible to distinguish between a tank that is truly clogged and the water level is rising, and a hinoki tank that is not clogged and the water level is rising, and which tanks truly require backwashing. It was difficult to know exactly.

As a countermeasure against this problem, it would be good to install the sewage inflow position at a sufficiently high position relative to the treated water outflow position, but this would not only make the volume of the septic tank itself unnecessarily large but also The difference in height between each type of connected septic tank causes the volumetric efficiency of the process itself to deteriorate,
Furthermore, as a result, various types of backwashing become more frequent, which has the disadvantage of using excessive backwashing energy and deteriorating the quality of treated water. A height difference occurs between the discharge position and the water level in the tank, and this is expressed as ΔP as shown in Figure 1.
ΔP is considered to be a pressure loss due to clogging. Therefore, ΔP increases in proportion to clogging, so in order to keep the water level in the tank constant in this state, the treated water discharge position should be lowered to a lower position. However, in reality, due to tank structure and piping problems, it is difficult to move the treated water discharge position and gradually lower it to a lower position without increasing the volume of the septic tank. be.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks and provides a fixed bed type sewage septic tank that makes it possible to continue sewage treatment without causing a rise in the water level in the tank even if the filling material of the septic tank becomes clogged. The purpose is to

[Key points of the invention]

This invention includes a device for detecting the water level in the tank, a device for diffusing gas into the outflow pipe and controlling the gas flow rate,
The water level in the tank is kept almost constant by changing the flow rate of gas into the outflow pipe in response to changes in the water level and suctioning and draining the treated water.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings. Second
The figure is a longitudinal cross-sectional view of a fixed bed type sewage septic tank that is an embodiment of the present invention, and two parts that are the same as those of a septic tank of a conventional structure are given the same reference numerals and explanations thereof will be omitted. This septic tank is provided with a pipe 8b branching from a pipe 8a in the tank of a conventional structure, which is passed into an outflow pipe 6 penetrating through the filling material 3.
A second air diffuser 1 is installed at the tip (near the bottom of the filler 3).
Install 5. Further, a flow rate adjustment valve 16 is provided near the branch point of the pipe 8b, and a float 17 floating on the water surface is linked to this flow rate adjustment valve 16.

In this structure, the sewage purification process is exactly the same as the conventional one, and if this operation is performed continuously, the filling material 30 will become clogged due to the thickening of the biofilm, and the water level in the tank will gradually rise. When this water level reaches a preset position, the second air diffuser 15. Flow rate adjustment valve 16. The water level is maintained by the action of a water level control device constituted by the float 17.

Here, the operation of the water level control device mentioned above will be explained in detail.
The second air diffuser 15 has the function of an air lift pump together with the outflow pipe 6, and its suction capacity increases or decreases depending on the gas flow rate discharged from the second air diffuser 15, so the water level rises and the float 17 When pushed up, the flow rate adjustment valve 16 opens, gas is discharged from the second diffuser 15, the above-mentioned air lift pump function is activated, and the treated water T is sucked and discharged.

As a result, ΔP decreases and the water level stops rising.

FIG. 3 shows another embodiment of the present invention, in which the water level detection electrode 18. Control unit 19. The water level is controlled using an electric valve 20. That is, when the water level in the tank rises at WH4, it is detected by the water level detection electrode 18, the electric valve 20 is opened in response to a signal from the control unit 19, and gas is discharged from the second diffuser 15 to discharge the treated water T. Suction and discharge. As a result, the water level in the tank decreases, and when it reaches the level WL, it is detected by the water level detection electrode 18, and the electric valve 20 closes.
Since the suction and discharge of the treated water T also stops, the water level in the tank starts to rise again. By repeating this operation, the water level in the tank fluctuates between WH and WL, but this does not pose a practical problem as long as the interval between WH and WL is set to several digits.

〔Effect of the invention〕

According to this invention, the water level in the septic tank is maintained constant by changing the gas flow rate diffused into the outflow pipe according to changes in the water level in the septic tank and sucking and draining the treated water.
Even if the filler becomes clogged, the treated water will not flow back from the inflow pipe, and there is no need to increase the height difference between the inflow position of sewage water and the outflow position of treated water, making it possible to downsize the septic tank. It is possible, especially in a fixed-bed sewage purification process in which a plurality of septic tanks are connected in series, the height difference between each septic tank can be reduced, and the volumetric efficiency of the process can be improved. In addition, the backwashing time is determined by checking the water pressure difference between the top surface of the filler and the bottom of the septic tank or the operating status of the electric valve, so the backwashing time can be accurately detected and backwashing operations can be easily automated. effective.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a conventional fixed-bed sewage septic tank, FIG. 2 is a vertical cross-sectional view of an embodiment of the present invention, and FIG. 3 is a vertical cross-sectional view of a different embodiment of the present invention. 1. Tank, 3. Filling material, 6. Outflow pipe, 15. Second diffuser, 16. Flow rate adjustment valve, 17. Float, 18
- Water level detection electrode, 19... Control unit, 20... Electric valve. Procedural amendment (own ship dated 30th 1980, Director General of the Japan Patent Office, Mr. Waka (Kuwao 1), case description Tokkun Sho (Sa-68099 address: 1-1-7 Tanabeshinden, Kawasaki-ku, Kawasaki City, subject of amendment) Uki's □1. , amend the claims of the specification as shown below: 1) Sewage is caused to flow into a tank having a filler inside, and the sewage is treated with microorganisms grown on the surface of the filler,
In a fixed bed type sewage septic tank in which treated water is discharged from an outflow pipe that penetrates the filling material from the bottom surface of the filling material and leads out of the tank from the side wall surface of the tank, a device for detecting a water level in the tank; The tank is equipped with a device that diffuses gas and controls the gas flow rate, and the water level in the tank is kept almost constant by changing the gas flow rate into the outflow pipe according to changes in the water level and suctioning and discharging the treated water. A fixed bed type sewage septic tank characterized by being designed to maintain 2. In the device described in claim 1, a float is used as a device for detecting the water level in the tank, and the flow rate of gas diffused into the outflow pipe is controlled by a flow rate regulating valve linked to the float. A fixed bed type sewage septic tank characterized by: 3) In the product described in claim 1, an electrode-type water level detector is used as a device for detecting the water level in the tank, and the control of the gas flow rate to be diffused into the outflow pipe is performed by the electrode-type water level detector described in item 1. A fixed bed type sewage septic tank characterized in that one electric valve is operated by a container. 2. On page 4, line 8 of the specification, after "Iru.", say the following:
Add.

Claims (1)

[Claims] 1) Sewage is caused to flow into a sealed tank having a filler inside, the wastewater is treated with microorganisms grown on the surface of the filler, and the treated water is filled from the bottom surface of the filler. A fixed bed type sewage septic tank that discharges water from an outflow pipe that penetrates the material and leads out of the tank from the side wall surface of the tank. The fixing device is characterized in that the water level in the tank is kept almost constant by suctioning and discharging treated water by changing the flow rate of gas into the outflow pipe according to changes in the water level. Floor-shaped sewage septic tank. 2. In the device described in claim 1, a float is used as a device for detecting the water level in the tank, and the flow rate of gas diffused into the outflow pipe is controlled by a flow rate regulating valve linked to the float. A fixed bed type sewage septic tank characterized by: 3) In the device described in claim 1, an electrode type water level detector is used as a device for detecting the water level in the tank, and control of the flow rate of gas diffused into the outflow pipe is operated by the electrode type water level detector. A fixed bed type sewage septic tank characterized by being operated by an electric valve.