JP2741756B2 - Septic tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a septic tank provided with a plurality of contact aeration tanks downstream of an anaerobic filter bed tank.

[0002]

2. Description of the Related Art In a conventional septic tank, downstream of an anaerobic filter bed tank,
In order to increase the processing capacity of contact aeration, for example, there is a type in which a contact aeration tank first chamber and a contact aeration tank second chamber are provided in series, but in such a contact aeration tank, The same density of contact material was provided along the flow to form a filter bed for colonization of aerobic microorganisms.

[0003]

In order to further increase the treatment capacity of the water to be treated, for example, it is conceivable to increase the density of the contact material as a whole.
By increasing the density of the contact material throughout,
Since the amount of the microorganisms settled increases, the microorganisms grow on the filter bed of the first contact aeration tank when the density of the contact material is increased to a certain degree or more, despite the fact that the processing capacity of organic matter should increase. Too much flow of the water to be treated is deteriorated, and as a result, the treatment capacity of the water to be treated may be rather reduced. It is also conceivable to make the density of the contact material coarser as a whole, but if the density is too low, the water to be treated easily passes through the subgrade of the contact aeration tank and the flow is improved, Since the fixing amount is reduced and the processing capacity for reducing the BOD is reduced, the water to be treated having a large BOD load cannot be processed. Therefore, it is extremely difficult to increase the treatment capacity of the water to be treated to a certain degree or more as a whole by increasing or decreasing the density of the contact material. In other words, a larger space is required, and larger equipment costs are required. Therefore, an object of the present invention is to provide a septic tank that can increase the biological treatment capacity and increase the treatment capacity of the water to be treated as a whole while keeping the flow of the water to be treated good without increasing the overall space. It is in.

[0004]

A characteristic feature of a septic tank according to the present invention is a septic tank provided with a plurality of contact aeration tanks downstream of a plurality of anaerobic filter tanks, wherein the upstream and downstream anaerobic filter tanks are vertically arranged. In addition to providing a filter bed made of a honeycomb tube-shaped filter medium that forms a passage of water to be treated communicating in the direction, a filter bed formed by laminating basket-shaped filter materials is provided in an anaerobic filter bed tank on the downstream side, and anaerobic on the downstream side is provided. The filter medium density is set higher in the filter bed tank, and the contact material consisting of honeycomb tube-shaped filter media of a predetermined density that forms the passage of the water to be treated that communicates with each contact aeration tank in the vertical direction is one by one. The contact material in the upstream contact aeration tank is made less dense than the contact material in the downstream contact aeration tank, and the anaerobic filter bed tank is treated from the contact aeration tank to the anaerobic filter bed tank. The point is that a return path for constantly circulating water is provided.

[0005]

When the water to be treated flows into the septic tank having the above-described structure, the water first flows into the anaerobic filter bed tank on the upstream side and also flows down along the honeycomb tube-shaped filter medium. Here, even if the solids are suspended in the water to be treated, the solids are blocked by the upper part of the filter medium and are not easily transferred downstream. Here, the clogged solids are anaerobically decomposed by anaerobic bacteria growing on the solids as a medium while being adsorbed on the filter medium, and are gradually subdivided into BOD components. Therefore, the solids that have undergone anaerobic decomposition are dispersed in the water to be treated as they are sequentially transferred downstream. On the other hand, the water to be treated is transferred to the downstream anaerobic filter bed tank while receiving the rectifying action of the filter material on the honeycomb tube. Therefore, the water to be treated is transferred to the downstream anaerobic filter tank in a state where solid matter is hardly mixed, and the main function of the anaerobic bacteria in the upstream anaerobic filter tank is as follows. It will be expended preferentially on the fragmentation of large solids. Further, when the water to be treated flows into the downstream anaerobic filter bed tank, the water to be treated flows together with the finely divided solids or BOD components (hereinafter, these are collectively referred to as solids, etc.). However, at this time, since the water to be treated advancing while randomly contacting the basket-like filter medium, the solids and the like efficiently contact the filter medium and are subjected to a higher anaerobic decomposition action. The water to be treated which has undergone the above treatment in the anaerobic filter bed tank flows into the contact aeration tank with a small amount of solid matter, so that the solid matter adheres to the filter medium in the contact aeration tank, and the solid matter The aerobic bacteria are unlikely to be abnormally propagated using the medium as a medium, and the aerobic bacteria are less likely to cause the contact material to be clogged. Here, since the density of the filter medium in the anaerobic filter bed tank is formed more densely on the downstream side, the anaerobic decomposition of solids and the like is sequentially performed while preventing clogging with solids and the like on the upstream side. The function of subdividing the water to be treated works sufficiently because the contact efficiency with the filter medium is set higher as the water to be treated moves to the downstream side, and it is possible to prevent adverse effects on the subsequent aerobic treatment. In addition, simply requesting the above-mentioned functions may be considered to be achieved by using a honeycomb tubular filter material or a contact material in any of the tanks. Even if the density is formed so that it becomes denser on the downstream side, there is a disadvantage that the rectifying action works due to the filter medium, and solids floating in the water to be treated are easily advected downstream. Conversely, if the above-mentioned basket-shaped filter material is used instead of the honeycomb-shaped filter medium, clogging is likely to occur on the inflow side of the water to be treated, and the anaerobic filter bed tank on the inflow side of the water to be treated has When solids regenerated by vaporization and concentration of treated water or solids that cannot be anaerobically processed and settle to the bottom are generated, if the solids adhere to the filter medium, anaerobic bacteria are adversely affected. If the filter bed of the anaerobic filter tank on the upstream side, which is the inflow side of the water to be treated, is made of a honeycomb tubular filter medium, the scum does not hinder the movement of the solid material in the vertical direction. The generation is smooth and the sludge is efficiently stored and stored in the upper part of the anaerobic filter tank on the upstream side, and also helps to exert the rectifying action of the water to be treated. In addition, among the solids, the suspended solids secondary to the sediment can also be floated on the upper part of the anaerobic filter bed tank. Clogging can be prevented, and the inconvenience that solids settled at the lower part of the anaerobic filter bed tank migrate to the downstream side can be suppressed. In the contact aeration tank, since the water to be treated needs to circulate in the tank, the use of the honeycomb tube-shaped filter medium makes it difficult to obstruct the flow of the water to be treated, and furthermore, the aerobic property of the filter medium Can suppress abnormal growth of bacteria,
In addition, the BOD can be efficiently brought into contact with the contact material, and the aerobic treatment of the water to be treated can be efficiently performed. for that reason,
It can contribute to preventing clogging in the contact aeration tank. Furthermore, since the density of the contact material in the upstream contact aeration tank is lower than the density of the contact material in the downstream contact aeration tank, microorganisms are fixed on the contact material in the upstream contact aeration tank. There is no danger of clogging due to too much
The flow of the water to be treated is kept good. On the other hand, since the contact material of the downstream contact aeration tank is denser than the contact material of the upstream contact aeration tank, although the organic matter concentration of the water to be treated becomes lower as going downstream, The processing capacity for reducing the BOD is well maintained in the contact material of the downstream contact aeration tank. Since one contact material is provided in each contact aeration tank, for example, when contact materials having different densities are provided in one contact aeration tank, the amount of microorganisms adhering to the contact material is reduced. Irregularities occur, and the treatment of the water to be treated varies, thereby causing too much microorganisms to settle locally in the contact aeration tank and hindering the circulation of the water to be treated in the tank.
Furthermore, the treatment efficiency of the water to be treated is reduced, or the microorganisms do not settle and are not used at all in a part of the filter medium, so that the volume of the septic tank is wasted and the septic tank itself becomes large as a result. The problem described above is unlikely to occur.

If a return path for constantly returning the water to be treated from the contact aeration tank to the anaerobic filter bed tank is provided,
Organic substances that tend to settle or float in the anaerobic filter bed tank and tend to stagnate are also flushed by the return flow and supplied to the contact aeration tank, so that the opportunistic microorganisms are successfully grown and fixed on the contact material,
As a result, reduction of BOD is promoted.

[0007]

According to the present invention, the space of the septic tank itself is not increased compared with the conventional septic tank in which the density of the contact material in the upstream contact aeration tank and the density of the contact material in the downstream contact aeration tank are the same. In addition, it was possible to provide a septic tank with high treatment efficiency capable of increasing the biological treatment capacity while maintaining the flow of the treatment water, and increasing the treatment capacity of the treatment water as a whole.

[0008]

Embodiments will be described below. As shown in FIG. 1, from the upstream side, an anaerobic filter bed tank N composed of an anaerobic filter bed tank first chamber N1 and an anaerobic filter bed tank second chamber N2, a contact aeration tank first chamber E1, and a contact aeration tank tank A contact aeration tank E composed of two chambers E2 and a sedimentation tank P are provided in this order to constitute a purification tank. The filter bed F1 in the first anaerobic filter tank N1 uses a honeycomb tube-shaped filter medium mesh having a coarse lattice spacing without clogging, and the filter bed F2 in the second anaerobic filter tank N2 is filled with a large number of basket-like filter materials. The first anaerobic filter bed tank N1
Of the filter bed F1. In the contact aeration tank first chamber, the second chamber, E1, and E2, the density of the contact material C1, which is the contact material C of the upstream contact aeration tank first chamber E1, is reduced by the downstream contact aeration tank. The density of the contact material C2, which is the contact material C of the second chamber E2, is made lower than that of the contact material C2.
C2 uses a honeycomb tube-like contact material of a grid net, and the contact material C1 has a grid spacing of 80 mm square, and the contact material C2 has a grid spacing of 50 mm square.
A contact aeration tank first chamber with contact materials C1 and C2 of the same density,
A disadvantage that only the contact material C1 of the conventional structure installed in the second chamber E1, E2 is clogged first;
In addition, while eliminating the conventional disadvantage that the processing ability to reduce the BOD is reduced due to reduced proliferation of microorganisms,
It was possible to provide a septic tank that efficiently treats the water to be treated without increasing the space. Anaerobic filter bed first room N1
Has a structure for removing coarse suspended matter in the water to be treated flowing from the inflow port 1 and has a first anaerobic filter tank, a second chamber,
N1 and N2 are provided with the filter beds F1 and F2 in order to inhabit anaerobic microorganisms that anaerobically decompose part of the organic matter in the water to be treated and to fix their biofilms. FIG. 2 shows the structure of the honeycomb tubular contact material used as the contact materials C1 and C2. The honeycomb tube-shaped filter medium mesh, which is the filter medium of the filter bed F1, has the same structure. The first and second contact aeration tanks, the first and second chambers, E1 and E2 are provided with the contact materials C1 and C2 in order to fix aerobic microorganisms that oxidatively decompose remaining organic substances and ammonia nitrogen in the water to be treated.
Is provided. In addition, a circulating flow of the water to be treated is generated in each of the contact aeration tanks E1 and E2, and the water to be treated containing organic matter is brought into good contact with the aerobic microorganisms fixed on the contact materials C1 and C2. Aeration tubes D1 and D2 are provided to supply air for constantly supplying necessary oxygen to the aerobic microorganisms. In order to prevent clogging of the contact materials C1 and C2 due to excessive attachment of biofilms and the like, backwash tubes R1 and R2 for bubbling air to separate the excessively attached biofilms and the like as separation sludge. Are provided below the contact materials C1 and C2, and the first contacting aeration tank is provided by the separated sludge.
In order to prevent the amount of suspended matter in the second chamber, the second chamber, E1 and E2 from increasing too much, the separated sludge is subjected to the anaerobic filter tank first chamber N.
1, air lift pumps A1 and A2, and a return path B are provided. The wastewater from the contact aeration tank second chamber E2 is provided with a sedimentation tank P and a disinfection tank 3 so that the solid suspension is settled and removed, then disinfected and discharged from the discharge port 2.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a septic tank according to the present invention.

FIG. 2 is a perspective view showing the structure of a honeycomb tubular contact material.

[Explanation of symbols]

 N Anaerobic filter bed tank E Contact aeration tank C Contact material B Return path

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuyuki Honda 1 at Takamatsu, Kosai-cho, Koga-gun, Shiga Prefecture Inside the Kubota Shiga Plant (72) Inventor Hiroyoshi Nakajima 2nd Takamatsu, Kosai-cho, Koga-gun, Shiga Prefecture 1 Kubota Corporation Shiga Plant (56) References JP-A-1-228593 (JP, A) JP-A-62-19294 (JP, A) JP-A 64-36096 (JP, U)

Claims (1)

(57) [Claims] A septic tank provided with a plurality of contact aeration tanks (E) downstream of a plurality of anaerobic filter bed tanks (N), wherein the upstream side has a plurality of contact aeration tanks .
Forming a passage for water to be treated vertically communicating with the anaerobic filter bed tank
If a filter bed made of honeycomb tubular filter media is provided,
In addition, a basket-shaped filter medium is laminated on the downstream anaerobic filter bed tank.
A filter bed is installed, and the density of the filter media becomes higher in the downstream anaerobic filter bed tank.
It is necessary to set the
Honeycomb tube of predetermined density forming passage for treated water
A contact material (C) composed of a filter medium is provided one by one, and the density of the contact material (C) in the upstream contact aeration tank (E) is adjusted to the contact material in the downstream contact aeration tank (E). A purification tank having a density lower than that of (C) and a return path (B) for constantly returning the water to be treated from the contact aeration tank (E) to the anaerobic filter bed tank (N).