JP3013872B2 - Biological denitrification equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biological denitrification for removing nitrogen in wastewater by subjecting nitrogen-containing wastewater to denitrification treatment by using granules formed in granular form from the wastewater containing nitrogen. The apparatus, in particular, the biological denitrification apparatus of the upflow biobed type, has granule sludge outflow prevention means for preventing the denitrifying bacteria granules floating in the denitrification tank from flowing out of the treated water outflow portion of the denitrification tank. It relates to improvement of biological denitrification equipment.

[0002]

2. Description of the Related Art Hitherto, as a biological denitrification apparatus for removing nitrogen in wastewater using microorganisms, an apparatus using an activated sludge method, a rotating disk method or the like is known.

[0003] However, these biological denitrification devices cannot be applied with a high load (0.5 kgN / m ³ d or more), and the treatment efficiency is poor.

[0004] In recent years, in order to improve the treatment efficiency of a biological denitrification apparatus, an upflow biological bed type biological denitrification apparatus using denitrifying bacteria granules has been proposed. As shown in FIG. 5, this apparatus has a raw water supply unit 32 and a denitrifying bacteria granule forming unit 33 at the bottom, and the denitrifying bacteria granule forming unit 33.
Gas collision part 34, gas collection part 35, treated water outflow part
Denitrification is performed in the denitrification tank 31 having 36, without using a carrier for attaching bacteria, forming granules 37 in which bacteria are formed in a granular form, and securing a high concentration of microorganisms in the denitrification tank 31. .

[0005]

Incidentally, in such a denitrification tank 31, when nitrogen gas generated in the denitrification tank 31 adheres to the surface of the granules, the granules 37 float and the denitrification tank 31 It is easily deposited on the upper liquid surface.

Since a treated water outflow portion 36 is formed above the denitrification tank 31, when a large amount of granules 37 are deposited, the granules 37 flow out of the treated water outflow portion 36 of the denitrification tank 31. As a result, the denitrifying bacteria granules in the denitrification tank 31 gradually decrease, and there is a possibility that the treatment efficiency may decrease.

[0007] In addition, by mixing the granules into the treated water, the BO of the granules themselves is reduced.
Since the D (biological oxygen demand) component and the SS (suspension substance) component are mixed into the treated water, the BOD component and the S
The S component increases and the quality of the treated water decreases. In addition, when the treated water whose water quality has deteriorated is discharged into a river or the like, there is a problem that the river or the like is contaminated.

On the other hand, in a regulating tank for regulating the raw water supplied to the denitrification tank, if oxygen is present in the raw water in the regulating tank, the deoxygenation reaction proceeds preferentially in the denitrification tank, and as a result, denitrification occurs. There has also been a problem that the efficiency of the reaction is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to prevent the above-mentioned denitrifying bacteria granules from flowing out of the denitrification tank and improve the denitrification efficiency. It is assumed that.

[0010]

Means for solving the above-mentioned problem include a raw water supply section 2 for supplying raw water and a denitrifying bacterium granule forming section 3 at the bottom portion. In a biological denitrification apparatus provided with a denitrification tank 1 having a gas collision part 4, a gas collection part 5, and a treated water outflow part 11 above, a granule 24 rising inside the denitrification tank 1 is stirred and settled. Is provided above the denitrification tank 1.

[0011] As an alternative, the adjusting tank 12 having a stirring means 25 for stirring the raw water supplied to the denitrification tank 1 is provided on the front side of the denitrification tank 1.

As still another means, the gas collecting unit 5
A return path 9 is provided from the gas collection unit 5 to the adjustment tank 12 in order to return the nitrogen gas collected in the step 2 to the adjustment tank 12.

[0013] A sprinkler shower is provided above the denitrification tank 1.
It is also possible to provide 26.

[0014]

That is, the above-described stirrer is provided at the upper part of the denitrification tank, and the upper part of the denitrification tank is stirred by the stirrer to release bubbles from the granules rising inside the denitrification tank and settle the granules. As a result, it is possible to prevent the granules from flowing out of the treated water outlet together with the treated water.

Further, since the regulating tank having the stirring means is provided on the front side of the denitrification tank, the raw water to be supplied to the denitrification tank is uniformly stirred to prevent solids and the like from settling out and supplied to the denitrification tank. Raw water quality can be made uniform.

Further, the nitrogen gas generated in the denitrification tank is
When forming and sending a return path for returning to the adjustment tank, since the nitrogen gas does not contain oxygen, the inside of the adjustment tank can be maintained in an anaerobic state without increasing the oxygen concentration in the adjustment tank. Therefore, the deoxygenation reaction can be suppressed in the denitrification tank, and the efficiency of the denitrification reaction in the denitrification tank can be improved.

When a sprinkler shower 26 is mounted on the upper part of the denitrification tank 1, even if the granules which could not be prevented from rising by the stirrer 7 rise to the liquid level, the granules are sprayed by the sprinkler shower 26. Can settle.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to an embodiment of a biological denitrification apparatus of an upflow biological bed type using a denitrifying bacteria granule.

In FIG. 1, reference numeral 1 denotes a denitrification tank, at the bottom of which a raw water supply section 2 for supplying raw water is provided.

Reference numeral 12 denotes an adjusting tank for making the properties of the raw water uniform. Raw water is supplied through a raw water line 30 connected to the adjusting tank 12, and a blow device as a stirring means in the adjusting tank 12 is provided.
Raw water is agitated by being blown by 25,
Denitrification tank 1 after uniforming so that solids etc. do not settle
Supplied to

Reference numeral 3 denotes a granule forming section containing denitrifying bacteria, which is laminated on the bottom of the denitrification tank 1.

Reference numeral 4 denotes a gas collision portion for separating nitrogen gas generated from the granules, which is formed in an umbrella shape.

Reference numeral 5 denotes a gas collecting portion for collecting gas generated in the denitrification tank 1, which is formed in a substantially truncated cone shape having an open bottom surface, and is provided slightly above the gas collision portion 4. I have.

Reference numeral 7 denotes a stirrer for separating air bubbles from the granules deposited on the upper part of the denitrification tank 1 and causing them to settle. The stirrer 7 is driven by a stirring blade 8 attached to the lower end of a stirring shaft 15. Denitrification tank 1 so that the upper part of
Attached to.

As shown in FIG. 2, the stirrer 7 has a stirrer shaft 15 connected to a motor 19 inserted through the center of the lid 6 of the denitrification tank 1, and extends into the denitrification tank 1 from outside the denitrification tank 1. ing. The stirring shaft 15 is rotated by a motor 19, so that the liquid above the denitrification tank 1 is stirred by the rotation of the stirring blade 8.

Reference numeral 20 denotes a water collecting trough having a cylindrical rising portion 28 at the center thereof and an opening 21 above the rising portion 28. Around the rising section 28, a treated water collecting section 22 for collecting treated water denitrified from the opening 21 is formed.

Reference numeral 11 denotes a treated water outflow pipe for allowing treated water collected in the treated water collecting part 22 to flow out of the denitrification tank 1. Is provided in the vicinity.

Reference numeral 9 denotes a return path for returning the nitrogen gas generated in the denitrification tank 1 and collected by the gas collection unit 5.
The return path 9 is connected to a water sealing tank 10.

Reference numeral 13 denotes a return path for returning the nitrogen gas accumulated in the upper portion of the water-sealed tank 10 to the adjusting tank 12. The return path 13 is provided with a flow rate measuring device 18 for measuring the flow rate of the nitrogen gas. ing. Reference numeral 14 denotes a discharge path that branches off from the middle of the return path 13 and discharges excess nitrogen gas to the atmosphere. Return path 13 and discharge path
14 is provided with valves a and b, respectively.

Reference numeral 16 denotes a return path 13 for returning excess gas in the upper part of the regulating tank 12.
The suction device 17 is connected to the surplus gas return path 16.

Next, a description will be given of an embodiment in which raw water is denitrified by using the biological denitrification apparatus 23 of the upward flow biological bed type having the above-mentioned configuration.

As described above, the granule forming section 3 is formed at the bottom of the denitrification tank 1, and the nitrogen in the raw water introduced through the raw water supply section 2 to the bottom of the denitrification tank 1 is removed. It is quickly converted to nitrogen gas by nitrifying bacteria.

This raw water has a nitrogen concentration of 100 to 1000.
It is pickling water containing mg / l.
Denitrification is performed at 0 to 35 ° C. and a cross-sectional flow rate of 0.5 to 6 m / h.

As described above, the nitrogen gas generated by the denitrifying bacteria and the like is generated as bubbles in water.
The nitrogen gas also adheres to the surface. Then, the granules 24 with the nitrogen gas attached to the surface float in the denitrification tank 1.

When the granules 24 thus floated are stirred by the stirring blades 8 of the stirrer 7, nitrogen gas adhering to the granules 24 is separated from the granules 24 and the granules 24 settle. It is possible to prevent the granules 24 from being deposited on the upper part of the surface.

Accordingly, the granules 24 do not flow out of the water collecting trough 20 through the opening 22 of the water collecting trough 20 at the upper part of the vaginal tub 1, and the granules 24 flow out of the tank through the outflow pipe 11.
24 can be prevented from flowing out. The treated water thus obtained has a nitrogen concentration of about 5 to 60 mg / l, and is a treated water of good quality.

Further, the nitrogen gas released from the granules 24 and the nitrogen gas generated as bubbles in the water are accumulated in the gas collecting section 5. The nitrogen gas has a raw water nitrogen concentration of 1
In the case of 00 to 1000 mg / l, about 0.1 to 1 m ^{3 is} generated per 1 m ^{3 of} raw water.

The nitrogen gas collected in the gas collecting section 5 is continuously sent to the water sealing tank 10 through the return path 9. Water seal tank 10
, The amount of nitrogen gas in the gas collecting unit 5 can be kept constant, and the pressure in the gas collecting unit 5 in the denitrification tank 1 can be kept constant.

When the amount of nitrogen gas stored in the water-sealed tank 10 is normal, the state is detected by the flow control device 18 and the valve a is opened, while the valve b is closed and the nitrogen gas is The raw water in the adjusting tank 12 is blown by the blowing device 25 through the return path 13. By blowing the raw water in the adjusting tank 12 with the nitrogen gas in this way, the raw water can be uniformly stirred and maintained in an anaerobic state, and the efficiency of the denitrification reaction in the denitrification tank 1 can be increased thereafter. .

On the other hand, if the amount of nitrogen gas sent to the adjusting tank 12 is larger than usual, the state is detected by the flow rate measuring device 18, and as a result, the valve b is opened while the valve a remains open, and the water sealing tank is opened. It is discharged from 10 through the discharge path 14 to the atmosphere.

Further, when the amount of nitrogen gas sent to the adjusting tank 12 is smaller than usual, the nitrogen gas is supplied to an excess gas return path.
The gas is sucked by a suction device 17 connected to 16, returns to the return path 13 through the excess gas return path 16, and is used as nitrogen gas sent into the adjustment tank 12.

As described above, in the present embodiment, the gas collection unit 5
The nitrogen gas accumulated in the tank and the nitrogen gas accumulated in the upper part of the adjustment tank 12 are reused as the nitrogen gas sent to the adjustment tank 12 through the return path 13, so that the nitrogen gas can be efficiently used. was gotten.

In the above embodiment, a water collecting trough 20 is provided at the upper part of the denitrification tank 1 to form a treated water collecting part 22, and the treated water is discharged from the treated water collecting part 22. The formation of the treated water recovery section 22 is not a condition. The treated water outflow pipe 11 may be provided directly above the denitrification tank 1 and the treated water may be discharged from the denitrification tank 1.

Further, in the above embodiment, the granules are prevented from rising from the outflow pipe 11 by preventing the granules from rising by stirring with the stirrer 7. As shown in FIG. 3A, a sprinkling shower 26 having a sprinkling means 29 may be provided above the denitrification tank 1, and water may be sprinkled from the sprinkling shower 26 onto the liquid surface of the denitrification tank 1. In this case, even if the granules float on the liquid surface without being prevented from rising by the stirrer 7, there is an effect that the granules can be settled by the sprinkling shower 26.

The sprinkling shower 26 is a sprinkling shower 26 composed of a pipe connected from the outside of the denitrification tank 1 as shown in FIG. 3A. The water for sprinkling may be ordinary tap water or treated water. May be reused. Further, as a specific shape of the water spray shower 26, a ring shape as shown in FIG. 3 (b) or a pipe in which a plurality of pipes as shown in FIG. 4 are arranged in parallel can be used. Shower 26
Are provided with a plurality of nozzles as watering means 29 evenly. In this embodiment, the nozzles are evenly arranged as the water spraying means 29. However, the shape, arrangement, and the like of the water spraying means 29 are not particularly limited.

Further, as shown in FIG. 3A, a mesh made of a wire mesh or the like is formed along the periphery of the rising portion 28 of the water collecting trough 20 so that the upper end thereof is higher than the upper end portion of the rising portion 28. The member 27 may be attached. In this case, even if the granules 24 that could not be settled by the stirrer 7 or the watering shower 26 remain near the liquid surface, the upper end of the mesh member 27 is higher than the upper end of the rising portion 28. Treated water recovery section because it is installed above
22 has the effect that the outflow of granules can be prevented. However, the size of the mesh of the mesh member 27 must be smaller than the diameter of the granule. In addition, the material may be stainless steel, plastic, or the like. In short, the mesh member 27 may be made of a material that is not corroded by raw water.

In the above-described embodiment, the nitrogen gas generated in the denitrification tank 1 is returned to the adjustment tank 12, and the inside of the adjustment tank 12 is blown with the nitrogen gas. Returning the nitrogen gas to the conditioning tank 12 is not a condition. However, when the return path 13 is provided to return the nitrogen gas generated in the denitrification tank 1 to the adjustment tank 12, the nitrogen gas generated in the denitrification tank 1 can be effectively used.

Further, in the above embodiment, the nitrogen gas generated in the denitrification tank 1 was transferred to the water sealing tank 10 and then sent to the adjustment tank 12, but the provision of the water sealing tank 10 is not a condition. A return path 13 may be directly connected from the nitriding tank 1 to the adjusting tank 12. Further, the return path 13 is provided with the flow rate measuring device 18 and the valve a. However, the provision of these elements is not a condition, and the structures of the discharge path 14 and the excess gas return path 16 are also limited to the above-described embodiment. It is not a condition, and the provision of these is not a condition.

In the above embodiment, the stirring shaft 15 is inserted through the center of the lid 6 so that the lower end of the stirring shaft 15 extends from the outside of the denitrification tank 1 into the denitrification tank 1. Although the stirrer 7 equipped with the stirrer 8 was used, the structure and the mounting method of the stirrer 7 are not limited to the above-described embodiment, and it is essential that the liquid in the upper part of the denitrification tank 1 be stirred. For example, when the stirrer 7 is mounted so that the position of the stirring blade 8 is located in the upper part near the gas collision part 4 and the gas collecting part 5, the floating granule 24 is moved to near the liquid level. The effect of being able to immediately settle without ascending is obtained.

Further, in the above embodiment, only the treatment for stirring and uniformizing the raw water is performed in the adjusting tank 12, but in addition, the pH of the raw water may be adjusted.

[0051]

As described above, the present invention has a raw water supply section and a denitrifying bacteria granule forming section at the bottom, and a gas collision section and a gas collecting section above the denitrifying bacteria granule forming section. ,
In a biological denitrification apparatus having a treated water outflow part, a stirrer for stirring the liquid surface is provided at the upper part of the denitrification tank,
By stirring the liquid surface of the treated water with the stirrer, the granules rising in the denitrification tank can be constantly settled, and the granules can be prevented from flowing out of the treated water outflow portion.

As a result, it is possible to prevent the granules from being reduced in the denitrification tank, and to maintain the high processing efficiency.

Further, since it is possible to prevent the granules from being mixed into the treated water, it is possible to prevent the quality of the treated water from deteriorating.

Further, when a return path for returning the nitrogen gas generated in the denitrification tank to the adjustment tank is provided, the nitrogen gas is effectively used to maintain the inside of the adjustment tank in an anaerobic state, and the denitrification tank is used. The effect that the processing efficiency can be maintained high can also be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a biological denitrification apparatus as one embodiment.

FIG. 2 is a schematic sectional view of a denitrification tank according to the present invention.

FIG. 3A is a schematic sectional view showing another embodiment of the denitrification tank according to the present invention, and FIG. 3B is a top view of a sprinkler shower.

FIG. 4 is a top view showing another embodiment of the watering shower according to the present invention.

FIG. 5 is a schematic sectional view of a conventional denitrification tank.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Denitrification tank 2 Raw water supply part 3 Denitrifying bacteria granule formation part 4 Gas collision part 5 Gas collection part 7 Stirrer 9 Return path 12 Adjustment tank 13 Return path

Claims (1)

(57) [Claims] A raw water supply section (2) for supplying raw water to the bottom and a denitrifying bacteria granule forming section (3), and a gas collision section (4) is provided above the denitrifying bacteria granule forming section (3). ), the gas capturing collecting unit (5), stirred in a biological denitrification apparatus having a denitrification tank (1) having treated water outflow part (11), the denitrification tank (1) granules increases the internal (24) Stirrer for sedimentation
(7) is provided above the denitrification tank (1), and an adjustment tank (12) having stirring means (25) for stirring raw water supplied to the denitrification tank (1) is provided in the denitrification tank (1). of disposed in front, yet return passage gas collecting unit in order to return the collected nitrogen gas adjusting tank into (12) in the gas collecting unit (5) from (5) to the adjusting tank (12) ( 9) A biological denitrification apparatus characterized by comprising: