JP3087914B2 - Aeration treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aeration apparatus for aerobically treating sewage, human waste, and wastewater containing organic substances in various industries.

[0002]

2. Description of the Related Art As an apparatus for aerobically treating wastewater containing organic substances, an apparatus for treating activated water in an aerobic aeration tank is widely used. In the conventional processing apparatus,
A diffuser that performs aeration with air using an aeration tank with a water depth of 10 m or less, typically 4 to 6 m, an oxygen aerator that performs aeration with high-concentration oxygen instead of air in the device, and a water depth of 10 m There is a deep aeration apparatus for performing aeration treatment with air using the above deep aeration tank.

[0003]

In the conventional aerobic treatment apparatus described above, in the aeration treatment apparatus, since the oxygen partial pressure is low and the gas-liquid contact time is short, the dissolved oxygen concentration per unit volume is also low. Activated sludge concentration (hereinafter referred to as ML) related to the treatment efficiency of wastewater while the installation area of the treatment device becomes excessive
SS. There is also a limit to improving the processing efficiency by maintaining a high concentration of). In the oxygen aerator, the oxygen partial pressure is high, and the dissolved oxygen concentration can be increased.
Although the SS can be maintained at a high concentration and the installation area of the processing apparatus can be reduced, there is a problem that the oxygen dissolving efficiency is low because the gas-liquid contact time is short.

Further, in the deep aeration apparatus, the oxygen dissolving capacity can be increased by the water pressure, and the installation area of the processing apparatus can be reduced. However, since the dissolved concentration of unnecessary carbon dioxide and nitrogen in the air also increases, the PH is increased. Activated sludge floats up due to the adhesion of fine bubbles generated by re-bubbling in the shallow layer to activated sludge, which lowers treatment efficiency and deteriorates sedimentation in the sedimentation tank at the subsequent stage. Due to fear, there is a problem that a vacuum deaeration tank must be installed between the aeration tank and the precipitation tank.

The present invention has been made in view of the above-mentioned problems of the prior art, and aims at improving the oxygen dissolving efficiency and increasing the dissolved oxygen concentration by taking advantage of the oxygen aeration apparatus and the deep aeration apparatus. To provide an aeration treatment apparatus capable of further improving the treatment efficiency by maintaining a high concentration, reducing the installation area of the treatment apparatus, and preventing the floating obstruction of the activated sludge caused by the generation of fine bubbles. And

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is to provide an aeration apparatus for aerobically treating water to be treated, comprising a supply port for treated water and a discharge port for treated water, and having a closed structure. In a deep aeration tank with a water depth of 10 m or more, a partition plate having a communication port above and below is vertically provided so that the water to be treated circulates and forms an ascending flow path and a descending flow path. An upper air diffuser for agitation and a lower air diffuser for supplying high-concentration oxygen in the lower layer are provided, and gas circulating in the upper air diffuser in the top space in the aeration tank is circulated to the upper air diffuser. This is an aeration processing apparatus provided with a flow path.

[0007]

The high-concentration oxygen produced by the oxygen generator is introduced into the water to be treated supplied to the aeration tank from the lower diffuser, and the gas remaining in the top space in the aeration tank is passed through the gas circulation channel. When the water to be treated is introduced from the upper aerator through the upper aerator, the water to be treated is aerobically treated while being circulated and circulated through the ascending flow path and the descending flow path of the aeration tank by the air lift effect. In the above, most of the high-concentration oxygen introduced from the lower aerator is dissolved in the water to be treated and used for the biological oxidation reaction, but nitrogen and some oxygen once dissolved in the deep layer are reused in the shallow layer. The gas is bubbled and stays in the top space in the aeration tank together with the undissolved gas for circulation.

[0008] The rebubbled nitrogen or the like is liable to become microbubbles and adheres to the activated sludge to cause a floating action. However, the adhering bubbles are agglomerated and separated by being stirred by the gas circulated from the upper diffuser. Therefore, the sedimentation of the activated sludge is promoted. When the dissolution efficiency is increased, the pH value is inevitably lowered due to the dissolution of the carbon dioxide gas, but the carbon dioxide gas can be purged by stirring the gas. The water to be treated is aerobic-treated for a certain residence time, but the dissolved oxygen concentration is maintained high due to the high oxygen partial pressure due to the deep layer and high-concentration oxygen, so that the water can be treated efficiently.

In the treated water treated in the aeration tank, activated sludge is settled and separated in the subsequent settling tank and discharged as clear water. A part of the activated sludge settled and separated is circulated to the aeration tank as return sludge, and the remaining part is supplied to an appropriate sludge treatment device as excess sludge for treatment.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the drawings showing one embodiment. FIG. 1 is a system diagram of one embodiment, and FIG. 2 is a system diagram of another embodiment in which a plurality of aeration tanks are connected in series. 1, a single aeration tank 1 is provided in FIG. 1, but a plurality of aeration tanks 1 are provided as shown in FIG. Aeration tanks 1a, 1b, 1
c is preferably provided continuously, and it is also preferable to provide a deaeration tank 14 at the last stage in order to sufficiently remove the bubbles attached to the activated sludge and reduce the power.

The aeration tank 1 is provided with a supply port 7 for the water A to be treated and a discharge port 8 for the treatment water B, and is a vertical tank having a closed structure and a depth of 10 m or more. In order that A circulates, communication ports 12a and 12b are provided on the upper and lower sides, and the partition plate 2 is vertically installed to form an ascending channel 3 and a descending channel 4.
In addition, an upper diffuser 5 for stirring is disposed in an upper layer of the ascending flow path 3, and a lower diffuser 6 for supplying high-concentration oxygen D is disposed in a lower layer thereof. Gas E staying in the top gap 9
Is provided to the upper air diffuser 5 using a circulation blower 11.

The water depth in the aeration tank 1 may be 10 m or more, but is preferably 10 to 20 m from the viewpoint of aeration power cost and equipment cost. Further, a sludge supply pipe 33 for supplying the returned sludge G from the subsequent settling tank 40 is connected to the aeration treatment device 20,
A gas outlet 13 for discharging excess gas F from the top space 9;
Is provided. The pressure in the aeration tank 1 is usually atmospheric pressure, but it is preferable to provide a pressure control valve at the gas outlet 13 when pressurizing.

The upper diffuser 5 and the lower diffuser 6 are preferably arranged at a depth of 4 to 6 m in the upper diffuser 5, and an aeration tank in the lower diffuser 6. Preferably, it is provided near the bottom of the first. In the above, the reason why the lower diffuser 6 is provided in the ascending flow path 3 is that, when the lower diffuser 6 is provided in the descending flow path 4, the reverse flow of the water to be treated A occurs when gas diffusion from the upper diffuser 5 is stopped. A stop state occurs immediately before that, and at this time, a temporary ejection phenomenon of gas occurs, which may hinder the operation of the apparatus.

Reference numeral 30 denotes a PSA type oxygen generator.
Other devices such as a cryogenic separation type may be used. The PSA type oxygen generator 30 is provided with an air compressor 22 from an air compressor 22 to a molecular sieve packed adsorption tower 21 comprising three or four towers.
Is introduced, and oxygen is adsorbed and desorbed by cyclically repeating pressurization and decompression to produce a high-concentration oxygen D, which is generally used. The concentration of the high-concentration oxygen D to be produced is preferably 70 vol% or more in order to minimize unnecessary dissolution of nitrogen.

Numeral 40 denotes a sedimentation tank 40 for sedimenting and separating activated sludge in the treated water B to obtain clarified water.
A sludge introduction pipe 33 that circulates a part of the sludge as return sludge G to the aeration tank 1, comprising a sludge scraper 31 for collecting the sludge;
The remaining sludge is discharged as surplus sludge H to a subsequent sludge treatment device (not shown). Further, an outlet 34 for the clear water J separated into solid and liquid is provided at the upper part.

The operation of the aeration treatment apparatus 20 of the present invention having the above-described configuration will be described in detail below. In FIG. 1, water A to be treated containing organic substances such as sewage and human waste supplied to an aeration tank 1
Is aerobic while being circulated and circulated through the ascending flow path 3 and the descending flow path 4 of the aeration tank 1 by an airlift effect of the high-concentration oxygen D produced by the oxygen generator 30 introduced from the lower diffuser 6. Is subjected to biological oxidation treatment. In the above processing, the returned sludge G from the settling tank 40 is supplied to the sludge introduction pipe 33.
However, the dissolved oxygen concentration becomes extremely high due to the effect of high concentration oxygen D and deep aeration.
S is maintained at a concentration of about 2 to 4 times that of a conventional activated sludge apparatus, and the treatment efficiency can be increased.

Further, in the above, nitrogen and a part of oxygen once dissolved in the deep part are rebubble in the shallow part to generate fine bubbles and adhere to the activated sludge to cause a floating action.
The gas E staying in the top space 9 of the aeration tank 1 is introduced from the upper air diffuser 5 by the circulation blower 11 through the gas circulation channel 10, so that the attached bubbles are coagulated and separated. Purging of the dissolved and dissolved carbon dioxide gas can be carried out, so that a decrease in PH value can be prevented. Further, by circulating the gas E, the effective use of oxygen is achieved, and the gas A has substantially the same oxygen concentration as the atmosphere, and is discharged from the gas outlet 13 as surplus gas F. It is to be noted that the release may be performed after being processed by a post-processing device (not shown).

In FIG. 2, aeration tanks 1a, 1a of the same shape are shown.
1b and 1c are connected in series via a partition 16 and a degassing tank 14 is provided at the last stage to aerate the gas E with a degassing diffuser 15. Rather than increasing the capacity of a single tank, shortening the residence time in one tank and proceeding with the treatment in three tanks improves the processing efficiency and the oxygen utilization efficiency. Further, the provision of the degassing tank 14 eliminates the need to continuously perform gas diffusion from the upper air diffuser 5, and can reduce power by sequentially intermittently diffusing gas. The sedimentation and separation of satisfactorily takes place.

The treated water B, which has been aerobically treated in the aeration tank 1 for a certain residence time, is introduced into the precipitation tank 40. Treated water B
The activated sludge therein is slowly stirred by the sludge scraper 31 to coagulate and settle, and is collected and discharged to the sludge discharge port 32.
In the above, a flocculant can be added as required to promote flocculation. A part of the discharged activated sludge is returned to the aeration tank 1 as returned sludge G, but the remaining is sludge H.
Is discharged out of the system and dewatered by a sludge treatment device such as a belt press dewatering machine at the subsequent stage. The supernatant water from which the activated sludge has been separated is discharged out of the system as a clarified water J and discharged as it is, or is discharged after being post-treated by a sterilizer or the like.

[0020]

According to the present invention having the structure and operation described above, the following effects can be obtained. B) Aeration of high-concentration oxygen under the deep layer greatly improves the oxygen dissolving efficiency and can keep the dissolved oxygen concentration high. B) The activated sludge concentration can be maintained at a high concentration, and the treatment efficiency can be improved. C) The installation area of the processing apparatus can be reduced. D) Floating of activated sludge in an aeration tank and sedimentation failure in a settling tank due to generation of fine bubbles can be prevented.

[Brief description of the drawings]

FIG. 1 is a system diagram of an embodiment.

FIG. 2 is a system diagram of another embodiment.

[Explanation of symbols]

20: aeration apparatus, 30: oxygen generator, 40: precipitation tank, 1, 1a, 1b, 1c: aeration tank, 2: partition plate, 3:
Ascending flow path, 4: descending flow path, 5: upper diffuser, 6: lower diffuser, 7: treated water supply port, 8: treated water discharge port, 9: top gap, 10: circulation flow path, 11: circulation blower, 12a:
Lower communication port, 12b: upper communication port, 13: gas discharge port,
14: deaeration tank, 15: deaerator, 16: partition, 2
1: adsorption tower, 22: air compressor, 31: sludge scraper, 3
2: Sludge outlet, 33: Sludge inlet pipe, 34: Clarified water outlet. A: treated water, B: treated water, C: air, D: high concentration oxygen, E: gas, F: surplus gas, G: return sludge, H: surplus sludge, J: clear water.

Claims (1)

(57) [Claims] An aeration apparatus for aerobically treating water to be treated, comprising a supply port for the water to be treated and a discharge port for the treated water, and having a closed structure in a deep aeration tank having a water depth of 10 m or more. An ascent passage and a descending passage are formed by vertically installing a partition plate having a communication port above and below so that the water to be treated circulates, and an upper diffuser for stirring in an upper layer of the ascending passage, A lower air diffuser for supplying high-concentration oxygen is provided in the lower layer, and a gas circulation flow path for circulating gas remaining in the top space in the aeration tank to the upper air diffuser is provided. Aeration treatment device.