JPH02184398A - Moving bed-type denitrification device - Google Patents

Abstract

PURPOSE:To prevent the clogging of the carrier and packed bed by providing a denitrification tower, an air-lift pipe, a carrier made of nonwoven fabric pieces, a diffuser and a carrier circulating cylinder also used for discharging back-washing water to the denitrification device. CONSTITUTION:Raw water and a nitrified circulating soln. are supplied to the denitrification tower 1, and air is blown from the diffuser 6. Consequently, bubbles ascend in the air-lift pipe 2, and an ascending flow of water is generated by the bubbles. The carriers 3 of the chopped nonwoven fabric are successively sucked into the air-lift pipe 2 from the lower part of the packed bed 4. The sludge adhered to the carrier 3 in high concn. by the propagation of denitrifying bacteria is released. The carriers 3 are continuously cleaned in this way, and the cleaned carriers 3 and the released sludge are introduced into the carrier circulating cylinder 8 from the upper opening 14 of the air-lift pipe 2. The back-washing water mixed with the released sludge is extracted from a back- washing water discharge pipe 10, whereas the cleaned carriers 3 descend on a conical plate 11 and are circulated to the upper packed bed 4 from an opening 12 through a circulating port 13. The carriers 3 are continuously backwashed in this way, and the clogging of the carrier 3 and packed bed 4 is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to nitrification solution circulation, which is one of the methods for treating υ1 water containing organic pollutants and nitrogen components, such as sewage and organic wastewater. The present invention relates to a moving bed denitrification device used to carry out the process.

[Prior Art] As a wastewater treatment method for the purpose of removing organic substances and nitrogen from wastewater, a nitrified liquid circulation method, which is a modification of the activated sludge method, has been known. FIG. 3 is a conceptual diagram of an apparatus for carrying out the conventional nitrification liquid circulation method using a carrier.
2 is an aerobic reactor filled with a carrier 24 made of sand, activated carbon, synthetic resin, etc.; 25 is a solid-liquid separation device such as sand filtration; 26 is an aeration device provided in the aerobic reactor 23;
7 is a blower, 28 is a nitrified liquid circulation pipe, and 29 is a circulation pump.

The raw water is first supplied to the denitrification tower 21, and is allowed to flow down through a covering material 22, such as a nonwoven fabric, filled and held in the tower.

During the flow of this raw water, denitrifying bacteria immobilized on the filter medium 22 utilize organic matter in the raw water to reduce nitrate nitrogen in the nitrification circulating fluid 28 and remove it as nitrogen gas. Next, the drained water is sent to the aerobic reactor 23, where the organic matter decomposing bacteria and nitrifying bacteria immobilized on the carrier 24 are fed with air blown from the air diffuser 26. It decomposes organic matter in wastewater, oxidizes organic and ammonia nitrogen, and produces nitrate nitrogen. This nitrate nitrogen is circulated to the denitrification tower 21 through the nitrification liquid circulation pipe 28 by two circulation pumps, and a part of the waste water from the aerobic reactor 23 is transferred to the nitrification liquid circulation pipe 21 as shown in ``1''.
8 is circulated to the denitrification tower 21, and the remainder is sent to the solid-liquid separator 25. Since sludge flocs separated from the carrier 24 are mixed in the waste water from the aerobic reactor 23, these 88 flocs are finally removed by the solid-liquid separator 25.
It is extracted as treated water.

[Problem to be solved by the invention] Since the conventional denitrification tower 21 is configured as described above,
On the filter medium 22, 88 minutes of raw water, exfoliated sludge from the aerobic reactor 23, and sludge grown in the denitrification tower 2 are fixed at a high concentration. As a result, the filter media 22 gets clogged and short passes occur, so to prevent this, the HarutjA 22 must be frequently washed (backwashed).
I had to. Moreover, backwashing lowers the concentration of adhered sludge and causes denitrifying bacteria to flow out, resulting in a significant drop in efficiency.

The present invention was made to solve this problem, and it enables continuous backwashing in a movable bed type by cutting a nonwoven fabric filter into pieces.
The purpose of this is to maintain a high sludge concentration in the carrier packed bed while preventing short passes due to l'' clogging, and to provide an efficient moving bed type denitrification device.

[Means for Solving the Problems] In order to achieve the above object, the moving bed type denitrification apparatus according to the present invention includes an air lift pipe provided in the denitrification tower, and a nonwoven fabric between the air lift pipe and the denitrification tower. A carrier made of shredded nonwoven fabric pieces is filled and held, an air diffuser is disposed below the air lift pipe, and a carrier circulation cylinder is provided above, which also serves as a discharge of backwash water.

Preferably, the denitrification tower is of a closed structure, and the inside of the denitrification tower is kept in an anaerobic state by supplying the air inside the denitrification tower to the aeration device.

[Function] In the present invention, an upward flow of water is generated in the air lift pipe by air bubbles blown from the air diffuser provided below the air lift pipe, and this upward flow causes water to flow inside the denitrification tower. The carriers made of the filled nonwoven fabric pieces are drawn into the air lift tube one after another starting from those in the lower layer of the packed layer, and rise within the tube. During this upward movement, excess sludge adhering to the carrier is washed away by air bubbles and water flow. The washed carrier then enters the carrier circulation cylinder which also serves as a backwash water discharge above the air lift pipe, and the backwash water is separately drawn out from the carrier circulation cylinder and processed, and the washed carrier is recycled again. It circulates to the upper part of the packed bed. Therefore, the sludge concentration of the carrier in the packed bed can be maintained high, and clogging of the carrier and the packed bed can be prevented.

[Example code] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram showing an embodiment of the present invention. In the figure, 1 is a denitrification tower, and an air lift pipe 2 is provided in the center of the tower. A packed bed 4 in which carriers 3 are filled and held is arranged between the air lift pipe 2 and the denitrification tower 1.
The carrier 3 is made of a nonwoven fabric cut into pieces of, for example, 1 to 4 cm square, and is held in the tower by a screen 5 or the like on the upper part to form the packed bed 4. However, if the specific gravity of the carrier made of nonwoven fabric is higher than that of water (for example, 1.04 or more)
does not require the above-mentioned screen 5. The lower part of the air lift pipe 2 is enlarged in diameter into a trumpet shape, and an air diffuser 6 is disposed below it. 7 is a blower for supplying air (nitrogen gas may be used) to the diffuser 6.

Reference numeral 8 denotes a carrier circulation cylinder disposed above the air lift pipe 2, in which backwash water after washing the carrier 3 stays, so the backwash water is discharged through a backwash water discharge pipe 10 with a valve 9. I'm trying to pull it out. A funnel-shaped opening 12 is formed between the lower end peripheral edge of the carrier circulation cylinder 8 and the conical plate attached to the upper part of the air lift tube 2, and this opening 12 is connected to a circulation port 13 provided in the screen 5. It's communicating. Therefore, the opening 14 at the upper end of the airlift tube 2 rises inside the airlift tube 2.
The carrier 3 that has come out of the carrier 3 moves down the conical plate 11 and circulates into the packed bed 4 through the opening 12 and the circulation port 13 . Reference numeral 15 denotes a water covering plate connected to the outer periphery of the upper cylindrical portion 6 of the carrier circulation cylinder 8, and supplies raw water and the nitrification circulating liquid from the aerobic reactor 23 shown in FIG.

17 is a drain pipe connected to the aerobic reactor 23.

Next, the operation of this embodiment configured as described above will be explained. Raw water and the nitrification circulating liquid from the aerobic reactor 23 are supplied to the denitrification tower 1 . The action of the denitrifying bacteria immobilized on the carrier 3 of the packed bed 4 is as described above. 17 years ago
Since an air lift mechanism is installed inside the denitrification tower 1,
When air is blown from the air diffuser 6, air bubbles rise inside the air lift tube 2, thereby causing an upward flow of water. For this reason, the carriers 3 made of pieces of nonwoven fabric cut into pieces are drawn into the air lift tube 2 one after another starting from the lower part of the packed layer 4 and ascend. A high concentration of sludge (=1) adheres to the carrier 3 due to the growth of denitrifying bacteria, and while the carrier 3 is moving up the air lift tube 2, air bubbles and water flow act to separate the sludge.In this way, the carrier 3 is continuously washed, and the washed carrier 3 and the sludge (excess sludge) separated from the carrier enter the carrier circulation cylinder 8 from the upper end 14 of the air lift pipe 2.

The backwash water mixed with peeled sludge is drawn out from the carrier circulation cylinder 8 through the valve 9 (=I) backwash water discharge pipe 10 and is treated separately as surplus sludge, but the carrier 3 after washing is removed from the conical plate 11.
It descends and circulates from the opening 12 through the circulation port 13 to the second layer portion of the packed bed 4. Since the carrier 3 can be backwashed continuously in this way, there is no short pass due to clogging of the carrier 3 and the packed bed 4, and the sludge concentration of the carrier 3 and the packed bed 4 can be maintained at a high concentration. can do. Also, the amount of denitrifying bacteria flowing out is small. Note that backwash water discharge and air lift backwash may be performed intermittently. Furthermore, even if the water flows out to the aerobic reactor side for 88 minutes, there is no direct effect on the treatment.

FIG. 2 shows another embodiment in which the denitrification tower has a closed structure, and the denitrification tower IA is sealed with a lid 8. The air in the denitrification tower IA is supplied to the diffuser 6 by the blower 7, and the air with a reduced oxygen concentration is used for airlift. The other configurations are the same as in FIG. 1. With this configuration, the supply of oxygen inside the tower can be suppressed and the inside of the denitrification tower A can be kept in an anaerobic state. Therefore, inhibition of the denitrification reaction by dissolved oxygen can be prevented.

[Effects of the Invention] As described above, according to the present invention, shredded nonwoven fabric is used as a carrier packed and held in a denitrification tower, and this carrier is continuously backwashed in a fluidized bed manner using an air lift pipe. The carrier after washing is circulated to the upper part of the packed bed through the carrier circulation cylinder, and the backwash water is drawn out from the carrier circulation cylinder.
Clogging of the carrier and the packed layer can be prevented, and troubles such as short paths do not occur. In addition, the sludge concentration in the carrier can be maintained at a high concentration, and the outflow of denitrifying bacteria is also small, so a highly efficient denitrifying device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing one embodiment of the present invention, FIG. 2 is a conceptual diagram showing another embodiment of the present invention, and FIG. 3 is a conceptual diagram showing a conventional wastewater treatment device. ]...Denitrification tower 2...Air lift pipe 3...Carrier 4...Filled bed 6...Aeration device 8...Carrier circulation cylinder 10...Backwash water discharge management agent Patent attorney Souji Sasaki 1dan 4K”

Claims (1)

[Claims] A denitrification tower, an airlift pipe provided in the denitrification tower, a carrier made of nonwoven fabric pieces filled and held between the denitrification tower and the airlift pipe, and a diffuser disposed below the airlift pipe. 1. A moving bed type denitrification device comprising: an air device; and a carrier circulation cylinder disposed above the air lift and pipe and serving also as backwash water discharge.