JPH05309379A - Water-purifier tank - Google Patents

Abstract

PURPOSE:To easily perform stable biological treatment while facilitating the adjustment of a flow rate by stabilizing the amount of returned water to be treated, in a water-purifier tank provided with an air supply device by providing a buffer space having a diameter larger than that of an air supply pipe on the way of the air supply pipe. CONSTITUTION:In a water-purifier tank, a contact aeration tank E is provided on the downstream side of an anaerobic filter bed tank N and the return passage returning the liquid in the contact aeration tank E to the anaerobic filter bed tank N from the lower part thereof is constituted of an air lift pipe Aa and the return pipe Ap connected to the upper part of the air lift pipe to guide the liquid to the anaerobic filter bed tank N and an air supply device B supplying air through an air supply pipe S is provided to the air lift pipe Ap. By providing a buffer space K having a diameter larger than that of the air supply pipe S on the way of the air supply pipe S, even when the pressure of the air from the air supply device B is changed, the change of pressure is absorbed by the buffer space K and the fluctuations of the blowoff amount of air bubbles into the air lift pipe Aa are prevented and the water level of the upper part of the air lift pipe Aa is stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a contact aeration tank downstream of an anaerobic filter bed tank, and provides a return path for returning the liquid in the tank from the lower part of the contact aeration tank to the anaerobic filter bed tank. The present invention relates to a septic tank including an air lift pipe and a return pipe connected to the upper portion of the air lift pipe so as to guide the liquid in the tank to the anaerobic filter bed tank.

[0002]

2. Description of the Related Art Conventionally, this type of septic tank has
Peeling sludge is obtained by performing biological treatment while naturally advancing from the anaerobic filter bed tank to the contact aeration tank, and returning part of the water to be treated in the contact aeration tank to the anaerobic filter bed tank via the return path. In addition to circulating treatment of nitric acid and nitrification liquid, a settling tank is installed downstream of the contact aeration tank, and the solid content is allowed to settle in this settling tank. It was.

The return path makes an air lift pipe rise from the bottom of the contact aeration tank, and forms an opening at the lower end of the air lift pipe for taking in the liquid in the tank,
An air supply pipe of almost the same diameter is connected in communication with the air supply device near the lower end from the air supply device, a box opened at the top is connected to the upper end of the air lift pipe, and a contact aeration tank is formed from one end of the box. A return pipe for overflowing and returning excess water was provided, and a return pipe for guiding the in-tank solution to the anaerobic filter bed tank was connected to the other end of the box.

[0004]

However, in the above configuration, when the amount of bubbles blown into the air lift pipe changes due to the pulsation of the air pressure supplied from the air supply device, the water level in the air lift pipe changes. However, if the water level fluctuates, the water pressure at the air supply pipe connection position also fluctuates due to the influence, so that a vicious cycle in which the bubbles are more unevenly blown into the air lift pipe is likely to occur. Therefore, the flow rates of the treated water returned to the anaerobic filter bed tank and the treated water returned to the contact aeration tank are likely to fluctuate, and it is difficult to adjust the flow rate of the treated water returned to the anaerobic filter bed tank. . However, for example, when the flow rate of the water to be treated returned to the anaerobic filter bed tank is small, the amount of nitrification solution returned to the anaerobic filter bed tank is small, and the amount of oxygen returned is also small. Although denitrification treatment is carried out to decompose, the amount of denitrification treatment is insufficient, and the concentration of delaminated sludge in the contact aeration tank tends to increase. On the other hand, conversely, if the flow rate of the water to be treated returned to the anaerobic filter bed tank becomes too large, the amount of oxygen returned to the inside of the anaerobic filter bed tank also becomes large, and the anaerobic treatment and denitrification itself become difficult to proceed. For these reasons, the conventional septic tank has a drawback that stable biological treatment is difficult to perform.
Therefore, the object of the present invention is to make a simple improvement.
It is an object of the present invention to provide a septic tank in which the flow rate of the water to be treated returned to the anaerobic filter tank via the return passage can be easily adjusted and stable biological treatment can be easily performed.

[0005]

To achieve this object, a septic tank according to the present invention is characterized in that a contact aeration tank is provided downstream of an anaerobic filter bed tank, and a liquid inside the tank is introduced from the lower part of the contact aeration tank. A return path for returning to the anaerobic filter bed tank, and an air lift pipe, and a return pipe for communicating the tank liquid to the anaerobic filter bed tank by communicating with the upper portion of the air lift pipe, and In a septic tank having an air supply device for supplying air to an air lift pipe via an air supply pipe, a buffer space having a diameter larger than that of the air supply pipe is provided in the middle of the air supply pipe. There are the following effects.

[0006]

Since a buffer space having a diameter larger than that of the air supply pipe is provided in the middle of the air supply pipe, even if the pressure of the air supplied from the air supply device pulsates, the pulsation in the buffer space does not occur. It is possible to prevent fluctuations in the amount of bubbles blown into the air lift pipe. as a result,
The water level above the air lift pipe is stable.

[0007]

EFFECT OF THE INVENTION Since the water level above the air lift pipe is stable, the flow rate of the treated water returned to the anaerobic filter bed tank is stable,
The flow rate can be adjusted easily and stable biological treatment can be performed easily.

[0008]

EXAMPLES Examples of the present invention 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 N2, a contact aeration tank E, and a precipitation tank P are treated water to be treated. The septic tank is constructed so as to flow in this order by natural advection.

The anaerobic filter bed tank N is provided with filter beds F1 and F2 for growing anaerobic microorganisms that anaerobically decompose organic substances in the water to be treated and fixing their biofilms. The contact aeration tank E is provided with a contact material C for fixing aerobic microorganisms that decompose organic matters remaining in the water to be treated and nitrify ammoniacal nitrogen, and generate a circulating flow of the water to be treated in the tank. At last, the aerobic microorganisms fixed on the contact material C are provided with an air diffuser D for well contacting the water to be treated containing the organic matter with the aerobic microorganisms and supplying the air that gives oxygen necessary for the aerobic microorganisms. .. Further, in order to prevent clogging due to excessive adhesion of biofilm or the like to the contact material C, the backwash pipe R for bubbling air to remove excess biofilm or the like as separation sludge is used as the contact material. It is installed below C, and in order to prevent the increase of suspended solids and BOD in the contact aeration tank E and to accelerate the denitrification treatment of nitrification liquid, the sludge and nitrification liquid are separated along with the water to be treated from the anaerobic filter bed. A return path A for returning to the first tank chamber N1 is provided. The return path A includes an air lift pipe Aa,
The air lift pipe Aa is communicatively connected to the return pipe Ap for guiding a part of the liquid in the tank to the anaerobic filter bed tank N.

As shown in FIGS. 1 and 2, the air lift pipe Aa rises vertically from the bottom of the contact aeration tank E, and an opening Ai for taking in the liquid in the tank to the lower end of the air lift pipe Aa. And a blower B which is an air supply device for supplying air to the air lift pipe Aa through the air supply pipe S provided in communication with the air supply pipe S from the air supply device. It is provided. An air chamber K, which is a buffer space having a diameter larger than that of the air supply pipe S, is provided in the middle of the air supply pipe S. The air from the blower B is connected so that it can be supplied to the air diffusing pipe D and the backwash pipe R in addition to the air lift pipe Aa. The air lift pipe Aa
An air lift pipe expanded portion A1 is formed in the upper part of the return pipe through a tapered portion At, and a return pipe expanded portion A2 is also formed in the return pipe, and the return pipe expanded portion A2 is connected to the air lift pipe. It is connected to the enlarged diameter portion A1. The diameter of the air lift pipe expanded portion A1 is open to the top, but a lid or the like having an air vent hole may be provided.

A notch 3 for returning surplus water to the contact aeration tank is formed in the expanded diameter section A2 of the return pipe, and an upstream side thereof has a notch 3.
A baffle plate 4 having an opening formed in the lower portion for allowing only water to be treated with few bubbles to pass therethrough to reduce waviness of the liquid surface is provided, and the fluctuation of the transfer liquid amount is suppressed also on the downstream side of the cutout portion 3. A baffle plate 5 having an opening at the bottom for allowing the water to be treated to pass therethrough is provided.

The water to be treated from the contact aeration tank E is transferred from the bottom to the settling tank P, and the supernatant of the settling tank P overflows and is guided to the disinfecting tank Q, where the solid disinfectant is added. Each tank is configured to be discharged from the discharge port Z after being contacted with and sterilized.

With the above construction, the flow rate of the water to be treated returned to the anaerobic filter bed tank N1 becomes stable and the flow rate can be easily adjusted, so that stable biological treatment can be performed.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

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

FIG. 2 is a vertical cross-sectional view of main parts of a return path and an air supply pipe.

[Explanation of symbols]

 A Return path Aa Air lift tube Ap Return tube B Air supply device E Contact aeration tank K Buffer space N Anaerobic filter bed S Air supply tube

Front Page Continuation (72) Inventor Dai Harada, 1 Takamatsu, Kosai-cho, Koga-gun, Shiga Prefecture, No. 1 Stock Company, Kubota Shiga Factory (72) Inventor Katsumi Hamada, No. 2, Takamatsu, Kosai-cho, Shiga Prefecture, Kubota Shiga Co., Ltd. in the factory

Claims (1)

[Claims] 1. A contact aeration tank (E) is provided downstream of the anaerobic filter bed tank (N), and the liquid in the tank is returned to the anaerobic filter bed tank (N) from the lower part of the contact aeration tank (E). The return pipe (A) for communicating with the air lift pipe (Aa) is connected to the upper part of the air lift pipe (Aa) to guide the liquid in the tank to the anaerobic filter bed tank (N) (Ap). And consists of
A septic tank provided with an air supply device (B) for supplying air to the air lift pipe (Aa) through an air supply pipe (S), wherein the air supply device is provided in the middle of the air supply pipe (S). A septic tank provided with a buffer space (K) having a diameter larger than that of the supply pipe (S).