JP4126832B2 - Aerobic filter bed tank and sewage septic tank equipped with this aerobic filter bed tank - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aerobic filter bed tank, a sewage purification tank, and a sewage treatment method. More specifically, the present invention relates to an aerobic filter bed tank suitably used for sewage treatment such as manure and miscellaneous wastewater. An aerobic filter bed tank provided with a water level sensor capable of detecting a rise in water level caused by clogging of the floor), a sewage septic tank provided with the aerobic filter bed tank, and sewage using these aerobic filter bed tanks or sewage septic tanks It is a processing method.
[0002]
[Prior art]
Generally well-known sewage septic tanks are usually anaerobic treatment tanks (first chamber and second chamber) partitioned by a partition wall, an aerobic treatment tank (aerobic filter bed tank), a precipitation tank (or treated water tank) and It consists of a disinfection tank. The sewage supplied from the inflow port is sequentially transferred from the first chamber of the anaerobic treatment tank to the downstream, finally sterilized in the disinfection tank, and discharged from the outflow port to the outside.
[0003]
Several structures of aerobic filter bed tanks in sewage septic tanks have been known in the past. However, as shown in FIG. 4, the applicant previously aerobically sandwiched a porous plate (not shown). The filter bed tank is divided into two beds, an upper filter bed (biological reaction layer or R zone) 1 and a lower filter bed (filter layer or F zone) 2, and each filter bed is filled with a particulate carrier, A structure has been proposed in which the diffuser members 4a and 4b are arranged under the floor and a washing drainage outlet 5a is provided at the boundary between the upper filter bed 1 and the lower filter bed 2 (Japanese Patent Laid-Open No. Hei 6-285484). At the time of washing the aerobic filter bed C (especially the lower filter bed 2) in this sewage septic tank, the air is diffused from the washing air diffuser 4b and then the upper filter bed 1 and the lower filter are passed through a transfer pump (air lift pump) 5. The washing waste water is drawn out from the washing drain outlet 5a provided at the boundary with the filter bed 2 and transferred to the upper part of the anaerobic treatment tank (first chamber), and between the aerobic filter bed tank C and the treated water tank D. Washing the aerobic filter bed C (especially the lower filter bed 2) by causing the treated water in the treated water tank D to flow back to the lower part of the aerobic filter bed C through an advection port 7 provided at the lower part of the partition wall. To do.
[0004]
At the time of washing, the lower filter bed is uniformly flowed by aeration, and floating suspension (also referred to as biofilm exfoliation sludge, hereinafter abbreviated as SS) trapped in the lower filter bed is released, The cleaning wastewater contains SS and is returned to the anaerobic treatment tank (first chamber) from the cleaning drainage outlet 5a.
[0005]
In addition, this cleaning is usually performed once a day for about 1 to 30 minutes at night by using a timer.
[0006]
[Problems to be solved by the invention]
However, the above-described method performs cleaning for a set time once a day regardless of the amount of sewage load. In particular, when the inflow load is low, the amount of SS captured per day in the filtration layer is small, and cleaning once a day is not necessary. Energy is wasted. Moreover, since the dissolved oxygen concentration of the liquid of a filtration layer is maintained with high, the dissolved oxygen of the treated water in a treated water tank tends to remain high. If this is returned to the first chamber of the anaerobic filter bed as cleaning wastewater, a large amount of dissolved oxygen is brought in, which adversely affects the anaerobic treatment in the first chamber of the anaerobic filter bed. The present invention is intended to solve such problems, and can treat sewage appropriately regardless of the amount of sewage load, high or low, aerobic filter bed tank, sewage septic tank, or sewage treatment that can contribute to energy saving. It aims to provide a method.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has the following configuration. That is, the present invention has two filter beds, a biological reaction layer (upper filter bed) 1 and a filter layer (lower filter bed) 2, and below each filter bed (here, “lower” means lower or lower). The same shall apply hereinafter), diffuser members 4a and 4b connected to the blower 9 are disposed, a washing drain outlet 5a is provided in the tank, and aerobic treatment of sewage (normal operation) the cleaning of the filtration layer 2 (cleaning process) and an aerobic filter bed tank C comprises means for switching between the switching means from the time when the water level sensor is disposed in the bath has detected more than predetermined water level It is an aerobic filter bed tank that is switched when a certain time (time lag) has elapsed .
[0008]
The present invention also relates to a sewage septic tank incorporating the aerobic filter bed tank, that is, a sewage septic tank including an anaerobic treatment tank, the aerobic filter bed tank, a treated water tank, and a disinfection tank in order from the upstream side. .
[0010]
Here, the drainage outlet 5a provided in the tank is preferably at the boundary between the upper filter bed 1 and the lower filter bed 2 or at the lower part of the aerobic filter bed tank in order to draw out the washed wastewater after washing. Or it arrange | positions under a filtration layer (lower filter bed).
[0011]
In the aerobic filter bed tank C of the present invention, it is standard to vertically arrange the biological reaction layer 1 as the upper filter bed and the filter layer 2 as the lower filter bed (that is, form a double bed). However, as a modification thereof, it is possible to arrange the biological reaction layer 1 side by side as the front filter bed and the filter layer 2 as the rear filter bed.
[0012]
[Action]
When clogging occurs in the filtration layer (lower filter bed), the amount of sewage supplied becomes dominant over the amount of sewage to be treated, and the water level of the aerobic filter bed is increased. When the water level exceeds a predetermined level, the water level sensor arranged in the tank detects this, and the aerobic filter bed tank is moved from the normal aerobic treatment operation to the inside of the aerobic filter bed tank by a command from the control unit. It switches to the operation | movement (washing | cleaning process) for wash | cleaning a filter bed (especially filtration layer).
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described more specifically with reference to the drawings.
FIG. 1 is a schematic diagram of a sewage septic tank according to the present invention. The sewage septic tank is partitioned into an anaerobic filter bed tank first chamber A, an anaerobic filter bed tank second chamber B, an aerobic filter bed tank C, a treated water tank D, and a disinfection tank E from the upstream side.
[0014]
The anaerobic filter bed first chamber A and the anaerobic filter bed second chamber B can be filled with a biological carrier such as a net-like cylindrical filter medium.
[0015]
The aerobic filter bed tank C has an upper filter bed 1 and a lower filter bed 2, and these filter beds are biological carriers such as sponge carriers (becomes a living body for organisms. Also called contact materials and filter media). To form a filter bed. The upper filter bed 1 and the lower filter bed 2 are partitioned by sandwiching a water-permeable porous plate material (which does not pass through a biological carrier but allows water and air to pass through freely). Further, a water-permeable porous plate material is disposed on the upper side of the upper filter bed 1 and the lower side of the lower filter bed 2, respectively, so that the biological carrier does not flow out.
[0016]
A diffuser member 4 a typified by a diffuser pipe is provided under the upper filter bed 1, and a diffuser member 4 b for cleaning the filtration layer is also provided under the lower filter bed 2. A large number of air holes are formed in the bottom of each of the air diffusers 4a and 4b (in the case of an air diffuser, the tube bottom). Further, at the boundary between the upper filter bed 1 and the lower filter bed 2, a cleaning / drainage outlet 5 a serving as a liquid suction port of the air lift pump 5 is provided.
[0017]
In the upper filter bed (biological reaction layer) 1, the water to be treated is treated in the presence of air (dissolved oxygen) diffused and introduced from the diffuser member 4a. It is aerobically treated by aerobic microorganisms that live in the carrier. That is, mainly, oxidation / decomposition of biochemical oxygen demand (BOD) and nitrification of ammonia proceed. The upper filter bed (biological reaction layer) is not limited to a fluidized bed, and may be a fixed bed.
[0018]
Further, in the lower filter bed 2, air is not diffused from the cleaning air diffusing member 4 b in normal operation (operation other than during cleaning). While consuming the carry-over oxygen (dissolved oxygen) from the upper filter bed 1 and continuing (semi-) aerobic treatment, SS is efficiently captured (filtered) using a stationary biological carrier. Therefore, the lower filter bed 2 is gradually clogged with the trapped SS. In order to release this clogging, the aerobic filter bed C (especially the lower filter bed 2) is washed by a method described later. At the time of this washing, air is diffused from the washing air diffusing member 4b arranged under the lower filter bed 2 to release SS from the biological carrier. Simultaneously with or after the aeration, the cleaning drainage containing SS is extracted from the cleaning drainage outlet 5a while supplying air to the air lift pump 5. The drawn washing waste water is returned to the anaerobic filter bed first chamber A.
[0019]
During the cleaning, the air diffused from the air diffuser 4a is normally stopped (the air diffuser may continue to operate).
[0020]
The treated water tank D communicates with the aerobic filter bed tank C through the advection port 7 at the lower part of the partition wall with the aerobic filter bed tank C. In the treated water tank D, the treated liquid (treated water) is stored. The main part of the air lift pump 5 is provided in this tank.
[0021]
During normal operation of the sewage septic tank (other than during washing), air is diffused from the diffuser member 4a below the upper filter bed 1, diffused from the diffuser member 4b for cleaning below the lower filter bed 2, and to the air lift pump 5 There is no air supply. At the time of washing the filter bed, the air diffused from the air diffuser 4a below the upper filter bed 1 is stopped, and instead, the air diffused from the air diffuser 4b below the lower filter bed 2 and air to the air lift pump 5 as well. The cleaning wastewater containing SS is extracted from the cleaning drainage outlet 5a, and returned to the first chamber A of the anaerobic filter bed tank. In the case of the example in FIG. 1, the cleaning water at this time uses the processing water of the processing tank water D (see also FIG. 2). In FIG. 2, the flow of the liquid in the cleaning process is indicated by arrows.
[0022]
FIG. 3 is an enlarged view of the water level sensor and the blower. The water level sensor 8 is installed above the aerobic filter bed tank 8. The height of the water level sensor 8 from the liquid level varies depending on the size and scale of the tank and the type and amount of sewage, and may be determined as appropriate. In one example, the height from the air diffuser 4a during normal operation is used. Considering the water level rise (about 5 cm) that increases due to air bubbles due to air diffusion and the water level rise at the inflow peak (about 3 cm), the position is about 10 cm above the constant water level. Starting the cleaning of the filtration layer 2, the water level sensor 8 is automatically performed when the elapsed time or al a predetermined time to detect the water level of the predetermined intracisternal solution (time lag). The filtration layer 2 has little resistance to water flow in the initial stage, but gradually becomes larger as SS is captured. If the clogged condition is exceeded, the inflow will prevail over the outflow and the water level will rise. Since the degree of clogging of the filtration layer 2 is proportional to the degree of rise in the water level, when the water level reaches a certain height, it is detected by the water level sensor 8, and a command is sent via the control unit 13. Wash. The washing time can be determined by a built-in timer, and is usually 1 to 30 minutes (more preferably 10 to 20 minutes). In addition, it is preferable to perform the washing | cleaning of the filtration layer 2 arbitrarily also by manual operation.
[0023]
When the water level sensor 8 detects the set water level, the signal is sent to the control unit 13 in the blower 9, and the electromagnetic valve 14 built in the blower 9 is switched by the signal from the control unit 13 to wash from the normal discharge port 11. The air supply destination is switched to the discharge port 12 for use. If it does so, air will be supplied to the air diffusion member 4b and the air lift pump 5 of the filtration layer 2 lower part, and washing | cleaning will start.
[0024]
Further, since the water level sensor 8 detects a predetermined water level, time to start cleaning a predetermined time from the time of discovery of the predetermined water level (e.g., 1-5 hours) is after the elapse of (time lag) . If the time lag is provided, the sewage in the biological reaction layer reaches the filtration layer in the meantime, and the SS to be treated is filtered by the filtration layer (in other words, the SS to be treated is not pushed out to the treatment water tank. )
[0025]
【The invention's effect】
According to the aerobic filter bed tank or the sewage purification tank of the present invention, the aerobic filter bed tank (especially the filter layer) is washed only when the filter layer is clogged. Depending on the situation, the wastewater is appropriately treated, which can contribute to energy saving. Further, for example, it is possible to cope with a case where the inflow load is very high and a plurality of washing steps are required per day.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a sewage septic tank according to the present invention.
FIG. 2 is a liquid flow diagram in a cleaning process of a sewage septic tank according to the present invention. The liquid flow is indicated by arrows.
FIG. 3 is an enlarged view of a water level sensor and a blower portion in FIG. 1;
FIG. 4 is a schematic diagram of a conventional aerobic filter bed tank.
[Explanation of symbols]
1: upper filter bed (biological reaction layer), 2: lower filter bed (filter layer), 3a, 3b: partition wall, 4a: air diffuser (air diffuser), 4b: air diffuser for cleaning (air diffuser), 5: Air lift pump, 5a: Cleaning drain outlet (air lift pump suction port), 5b: Air lift pump pumping pipe, 7: Advection port, 8: Water level sensor, 9: Blower, 10: Blower main body, 11: Normal discharge Outlet, 12: Discharge port during cleaning, 13: Control unit, 14: Solenoid valve A: Anaerobic filter bed tank 1st chamber B: Anaerobic filter bed tank 2nd chamber C: Aerobic filter bed tank D: Treated water tank E: Disinfection tank

Claims (2)

It has two filter beds, a biological reaction layer (upper filter bed) and a filter layer (lower filter bed), and an air diffuser connected to a blower is placed under each filter bed. An aerobic filter bed tank having a drawing port and further comprising means for switching between aerobic treatment (normal operation) of sewage and washing process (washing process) of the filtration layer, wherein the switching means is disposed in the tank. An aerobic filter bed tank that is switched when a certain time (time lag) has elapsed since the water level sensor detected a water level above a predetermined level.   A wastewater purification tank comprising an anaerobic treatment tank, an aerobic filter bed tank according to claim 1, a treated water tank, and a disinfection tank.

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