JP4242025B2 - Air diffuser for cleaning filter layer, aerobic filter bed tank and septic tank - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a filter layer cleaning air diffuser, an aerobic filter bed tank, and a sewage purification tank, and more specifically, an aerobic filter bed tank suitably used for sewage treatment such as manure and miscellaneous wastewater, and the aerobic filter bed thereof. The present invention relates to a diffuser tube suitable for washing a filtration layer (or lower filter bed) of a tank, and a sewage purification tank equipped with these.
[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 beds in the sewage septic tank are conventionally known, but the applicant previously sandwiched a porous plate (not shown) as shown in FIG. 5 (A). The aerobic filter bed tank is divided into two beds, an upper filter bed (biological reaction layer or R zone) and a lower filter bed (filter layer or F zone), and each filter bed is filled with a granular carrier. A structure was proposed in which aeration pipes 4a and 4b were installed under the filter bed, and a cleaning drainage outlet 5a serving as a liquid suction port for a transfer pump (air lift pump) 5 was installed in the lower part of the aerobic filter bed tank C ( JP-A-9-248584). At the time of washing the aerobic filter bed tank C in this sewage septic tank, after aeration from the diffuser pipes 4a and 4b under the two filter beds, the washing drainage of the lower part of the aerobic filter bed tank via a transfer pump (air lift pump) 5 The washing waste water is withdrawn from the extraction port 5a and transferred to the upper part of the anaerobic treatment tank (first chamber), and the advection water from the anaerobic treatment tank (second chamber) pushed out with the transfer is aerobic filter bed tank C is introduced into the upper filter bed.
[0004]
During the washing, the lower filter bed is uniformly flowed by aeration, and the suspended suspension (also referred to as biofilm peeling sludge, hereinafter abbreviated as SS) trapped in the lower filter bed is peeled off. Then, it is returned to the anaerobic treatment tank (first chamber) from the cleaning drain outlet 5a as cleaning drain containing SS. At this time, the amount of the cleaning waste water to be drawn is determined by the area of the bottom surface of the aerobic filter bed tank C and the speed of the cleaning waste water passing through the bottom surface.
[0005]
As the air diffuser used here, in many cases, both for the upper filter bed and for the lower filter bed, as shown in FIG. A ring-shaped diffuser with small holes in the space.
[0006]
[Problems to be solved by the invention]
However, in this aerobic filter bed tank, the area of the washing drain outlet 5a is smaller than the area of the bottom of the filter bed (cannot be increased), so the SS far from the washing drain outlet 5a is together with the washing drain. It tends to settle to the bottom of the aerobic filter bed before being discharged into the aeration. The settled SS stays in the place and becomes anaerobic, which is one of the causes of reducing the performance of the aerobic filter bed tank.
The present invention is intended to solve such a problem, and an SS far from the cleaning drain drawing port 5a can be discharged together with the cleaning drain without retaining the SS in the vicinity of the floor surface, and stable performance can be maintained. It aims at providing an aerobic filter bed tank or a sewage septic tank.
[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, the aerobic filter bed vessel C having two filter bed filled with biological carriers which are arranged in the order of the biological reaction layer 1 and the filtration layer 2 from the upstream, the bottom or lower side of the filtration layer 2, a sparge tube conforms to the shape of the bottom surface of the aerobic filter bed tank installed horizontally, a large number of holes are formed at predetermined intervals in the pipe length direction in the tube bottom in the diffuser tube, said hole intervals, the closer to the detergent drain drawing port 5a to the liquid inlet of the transfer pump to pull out the washing waste water aerobic filter bed tank provided below the filter layer narrow, farther widely formed from the detergent drain extraction port 5a It is the air diffusion pipe (4p and 4q) for filtration layer washing | cleaning characterized by being characterized.
In this invention, the diffuser tube which adapts the shape of the bottom face of the aerobic filter bed tank may be formed in a ring shape or a U shape.
[0008]
The present invention also has two filter beds, a biological reaction layer 1 and a filtration layer 2, and the filtration layer cleaning air diffuser is disposed below the filtration layer 2. It also relates to an air filter bed tank.
[0009]
The present invention further relates to a sewage septic tank incorporating the aerobic filter bed tank, that is, a sewage septic tank provided with an anaerobic treatment tank, the aerobic filter bed tank, a treated water tank, and a disinfection tank in order from the upstream side. .
[0010]
In the aerobic filter bed tank C in the present invention, the biological reaction layer 1 is usually arranged vertically with the filter layer 2 as the lower filter bed (that is, a double bed is formed). As a variant, it is also possible to arrange the biological reaction layer 1 side by side as the front filter bed and the filter layer 2 as the back filter bed.
[0011]
Further, the site of the cleaning drainage outlet 5a provided in the aerobic filter bed tank C is preferably below the filtration layer 2 (or the lower part of the aerobic filter bed tank C), and the cleaning drainage outlet is a transfer pump (usually, The liquid suction port of the air lift pump 5 is preferably used.
[0012]
[Action]
In the diffuser for cleaning the filtration layer of the present invention, small holes are formed in the pipe lower portion in the tube length direction so as to be narrower as it is closer to the cleaning drainage outlet 5a, and to be wider from the cleaning drainage outlet 5a. When air is discharged from the small holes, the number of the bubbles rising along the partition wall 3a on the side of the cleaning / drainage outlet 5a is larger than the bubbles rising along the partition wall 3b on the opposite surface, and the ascending force is strong. As a result, the partition wall 3a side has a negative pressure more than the other part, and the other part is drawn, and a swirling flow is generated in the aerobic filter bed tank. This swirling flow causes a flow toward the washing drain outlet 5a near the bottom of the aerobic filter bed tank. Therefore, the SS in the vicinity of the bottom of the aerobic filter bed tank is also pulled out along with this flow from the cleaning drainage outlet 5a together with the cleaning drainage (see also FIG. 2 of the liquid flow occurring during the filtration layer cleaning).
[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 an example of an aerobic filter bed tank according to the present invention, and FIG. The aerobic filter bed tank C is filled with a biological carrier (becomes a living organism, also called a contact material or a filter material) to form a filter bed. The filter bed to be formed is divided into an upper filter bed (biological reaction layer) 1 and a lower filter bed (filter layer) 2, and a water-permeable porous plate (biological material) is interposed between the upper filter bed 1 and the lower filter bed 2. Compartment with water and air freely passing through) 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.
[0014]
An air diffuser 4a is provided under the upper filter bed 1, and an air diffuser for cleaning the filtration layer of the present invention is provided under the lower filter bed 2. Further, a cleaning drainage outlet 5 a serving as a liquid inlet of the air lift pump 5 is provided at the lower part of the aerobic filter bed C.
[0015]
Water treatment in the aerobic filter bed tank C is performed in the biological carrier in the presence of air (dissolved oxygen) aerated and introduced from the diffuser 4a in the upper filter bed (biological reaction layer) 1. It is aerobic treated by aerobic microorganisms that inhabit. That is, mainly, oxidation / decomposition of biochemical oxygen demand (BOD) and nitrification of ammonia proceed.
[0016]
Further, in the lower filter bed 2, in the normal operation (operation other than the time of cleaning), the aeration pipe 4p for cleaning the filtration layer is not aerated. A function to continue (semi) aerobic treatment while consuming the carry-over oxygen (dissolved oxygen) from the upper filter bed 1 and to efficiently capture (filter) SS using a stationary biological carrier There is. Therefore, the lower filter bed 2 is gradually clogged with the captured SS. In order to release this clogging, the aerobic filter bed C (particularly the lower filter bed 2) is periodically washed (usually once a day for about 1 to 30 minutes at night). At the time of this washing, aeration is carried out from the filter layer washing air diffuser 4p provided under the lower filter bed 2 to release SS from the biological carrier. Simultaneously with the aeration or after the aeration, the cleaning waste water containing SS is extracted from the cleaning drain outlet 5a. An air lift pump 5 is preferably used for this drawing.
[0017]
Further, the aeration from the air diffuser 4a of the upper filter bed 1 during the cleaning may be continuously operated during the cleaning, or may be temporarily stopped during the cleaning.
Cleaning can be performed automatically by using a timer or the like. It is preferable that the time, time, and frequency can be set arbitrarily.
[0018]
FIG. 1B is a schematic view of the air filter 4p for cleaning the filtration layer of the present invention as viewed from the bottom of the aerobic filter bed tank. As shown in the figure, the filter layer cleaning air diffuser 4p is in a ring shape that matches the shape of the bottom of the aerobic filter bed tank, and the tube thickness is about 13 mm to 25 mm. The holes are not formed at regular intervals, but are narrower as they are closer to the washing drain port 5a provided in the aerobic filter bed C, and are wider as they are farther from the washing drain port 5a. Yes. ₁₀ mm to 90 mm intervals at the closest location (L ₁ ) to the cleaning drainage outlet 5 a, and 100 mm to 200 mm intervals at the farthest location (L ₂ ) from the cleaning drainage outlet 5 a, and L ₂ / L ₁ is 1.1 to 20. The size (diameter) of the small hole is preferably about 1 mm to 5 mm. These ranges may vary depending on the size and size of the aerobic filter bed tank (or sewage septic tank).
Further, the diameter of the cleaning drainage outlet 5a and the cleaning drainage extraction speed (cleaning speed) also vary depending on the scale and size of the aerobic filter bed tank (or sewage septic tank). What is necessary is just to determine suitably by preliminary experiment etc. In one example, the diameter of the cleaning drainage outlet 5a was 75 mm, and the cleaning drainage extraction speed (cleaning speed) at this time was 4.0 m / h.
FIG. 2 shows a typical liquid flow (arrow) that occurs in the tank when the filtration layer is washed in the aerobic filter bed tank.
[0019]
FIG. 3 is an example of an aerobic filter bed tank using a U-shaped filtration layer cleaning air diffuser 4q having a plan view shape (different from a ring shape). Even when such a filter layer cleaning air diffuser 4q is used, there are the same operations and effects as when the ring-shaped filter layer cleaning air diffuser 4p is used.
[0020]
FIG. 4 is a schematic diagram of the configuration of a sewage septic tank using the filter layer cleaning air diffuser or the aerobic filter bed tank of the present invention.
This sewage septic tank has an anaerobic filter bed first chamber A, an anaerobic filter bed second chamber B, an aerobic filter bed C (having an upper filter bed 1 and a lower filter bed 2), and a treated water tank D from the upstream side. The sterilization tank E is divided into each tank.
The first chamber A and the second chamber B of the anaerobic filter bed tank can be filled with a biological carrier such as a mesh-like cylindrical filter medium, and the upper filter bed 1 and the lower filter of the aerobic filter bed tank C. The floor 2 can be filled with a biological carrier such as a sponge carrier.
The treated water tank D is provided with an air lift pump 5 necessary for washing the lower filter bed 2 of the aerobic filter bed tank C, and a liquid suction port of the air lift pump is provided at the lower part of the aerobic filter bed tank C. . The washing waste water extracted from here is returned to the first chamber A of the anaerobic filter bed tank.
[0021]
During normal operation of the sewage septic tank (other than during washing), air is supplied to the diffuser pipe 4 a below the upper filter bed 1, and air is supplied to the filter bed washing diffuser pipe and the air lift pump 5 below the lower filter bed 2. Do not supply. At the time of washing, when air is supplied to the air filter for cleaning the filtration layer below the lower filter bed 2 and the air lift pump 5, a swirling flow is generated in the filter bed, and this swirling flow is washed and drained near the bottom of the aerobic filter bed tank. A flow toward the mouth 5a is caused. Along the flow, the SS near the bottom of the aerobic filter bed tank is withdrawn from the washing drain outlet 5a together with the washing drain without staying at the bottom.
[0022]
【The invention's effect】
According to the aeration pipe or aerobic filter bed tank for filtration layer washing of the present invention, SS far from the washing drain outlet can be discharged together with the washing drainage without settling and staying at the bottom of the aerobic filter bed tank, Good aerobic filter bed performance can be secured.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an aerobic filter bed tank according to the present invention, wherein (A) is a schematic view of a configuration viewed from the side, and (B) is a schematic view of the diffuser for cleaning the filtration layer from the bottom.
FIG. 2 is a view showing a liquid flow that occurs during cleaning of the filtration layer in the aerobic filter bed tank according to the present invention. The liquid flow is indicated by arrows.
FIG. 3 is a schematic view of an aerobic filter bed tank according to another embodiment of the present invention looking up from the bottom surface of a filter layer cleaning air diffuser.
FIG. 4 is a schematic diagram of a wastewater septic tank according to the present invention (viewed from the side).
5A is a schematic diagram of a conventional aerobic filter bed tank as viewed from the side, and FIG. 5B is a schematic view of the diffuser tube looking up from the bottom.
[Explanation of symbols]
1: Upper filter bed (biological reaction layer) 2: Lower filter bed (filter layer)
3a, 3b: Partition wall 4a: Air diffuser 4b: Air diffuser 4p (for filter layer cleaning) 4p: Air diffuser for filter layer cleaning 4q: Air diffuser for filter layer cleaning 5: Air lift pump 5a: Cleaning drain outlet (Air lift pump suction) mouth)
5b: Air lift pump pumping pipe 7: Transfer port 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 (4)

From the upstream aerobic filter bed vessel having two filter bed filled with biological carriers which are arranged in the order of the biological reaction layer and the filtration layer, aerobic filter bed installed horizontally at the bottom or below the filter layer A diffuser tube adapted to the shape of the bottom surface of the tank , wherein a plurality of holes are formed at predetermined intervals in the tube length direction in the lower portion of the diffuser tube, and the interval between the holes is provided below the filtration layer. closer to detergent drain drawing port the liquid inlet of the transfer pump to pull out the washing waste water aerobic filter bed vessel narrowing, the detergent drain is from extraction port is farther wider, filter layer cleaning diffusing tube. The air diffusion tube for cleaning a filtration layer according to claim 1, wherein the air diffusion tube adapted to the shape of the bottom surface of the aerobic filter bed tank is formed in a ring shape or a U shape . An aerobic filter bed tank having two filter beds, a biological reaction layer and a filter layer, and the filter layer cleaning air diffuser of claim 1 or 2 disposed below the filter layer. A sewage purification tank comprising an anaerobic treatment tank, an aerobic filter bed tank according to claim 3 , a treated water tank, and a disinfection tank.

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