KR101242785B1 - Fluidized bed-type biological treatment apparatus - Google Patents

Abstract

assignment
An object of the present invention is to provide a fluidized bed biological treatment apparatus having good fluidity of a carrier and high biological treatment efficiency.
Solution
The fluidized bed biological treatment apparatus 1 is fixed to a cylindrical body 2 having a cylindrical axial direction in a vertical direction, a drive shaft 3 disposed at an axial center position of the body 2, and a drive shaft 3. Rotating blades 4, a baffle plate 5 formed only in the upper part of the inner circumferential surface of the body 2, an overflow port 7 formed in the upper part of the body 2, and a treated water extraction trap 6. have. The length H ₂ below the water surface position WL of the baffle plate 5 is preferably 5 to 20%, particularly 10 to 15% of the water depth H ₁ of the shell 2.

Description

FLUIDIZED BED-TYPE BIOLOGICAL TREATMENT APPARATUS

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized bed biological treatment apparatus for treating wastewater, and more particularly, to a fluidized bed biological treatment apparatus adapted to flow a carrier by a rotary vane.

For the purpose of high load and water quality improvement of wastewater biological treatment apparatus, a fluidized bed biological treatment apparatus using a carrier to which microorganisms are attached at high concentration is known. It is also known to use a rotary blade as a means for stirring this support (patent documents 1 and 2).

In patent document 1, in the biological reaction apparatus which arrange | positions a stirring blade at the bottom part of the center part of a reaction tank, and makes a support made from a porous cellulose carrier, it is described that the fixed blade was formed radially in the upper center of the tank. By forming this fixed vane, the flow which collects to the center in the vicinity of the water surface can generate | occur | produce, and a strong downflow can be formed and a support | carrier can be submerged (paragraph 0011 of patent document 1).

In Patent Document 2, a stirring blade is disposed at the center of the upper portion of the nitrogenization reactor containing a cellulose carrier having a particle diameter of 4 mm, and a baffle is formed at the center of the bottom surface of the reactor to form a strong tornado-like upward flow at the center of the tank. Is described.

In a biological treatment method using a carrier to which microorganisms are attached at a high concentration, in a case where the biological treatment reaction is a reaction for generating a gas such as an anaerobic methane gas or a denitrification nitrogen gas, the carrier to which the microorganism is attached is Specific gravity may be 1.0 or less by containing gas.

In order to make the carrier with a specific gravity of 1 or less flow in the tank, it is preferable to generate the up-and-down circulation flow by the structure which has a stirring blade and a baffle plate, such as a turbine blade and a propeller blade.

In Patent Document 3, in order to improve the mixing efficiency in the stirring tank, it is described to form a baffle plate in the vertical direction on the inner circumferential side of the tank provided with the stirring blades in the central shaft portion.

Japanese Laid-Open Patent Publication 2000-254682 Japanese Laid-Open Patent Publication 2002-143889 Japanese Unexamined Patent Publication No. 4-346826

Generally, in order to obtain high treated water quality, increasing the filling rate of the carrier is an effective means. However, in the case where the baffle plate is formed over the entire height of the body as in Patent Document 3 and FIG. 4 described later, a good flow cannot be obtained under the conditions of high filling factor of the carrier, and the solid-liquid mixing becomes poor.

That is, if a vertical blockage plate is formed on the inner circumferential surface of the body in the longitudinal direction, a strong upflow or downflow occurs along the inner circumference of the body, but the return flow rate to the stirring blade near the central axis is smaller than that of the upstream, A carrier having a specific gravity of 1.0 or less is accumulated on the top of the reactor. For this reason, the filling rate of the reactor upper part is remarkably high. The carrier is likely to be stagnant due to the interference between the carriers and the interference between the carrier and the baffle plate.

In the case where the longitudinal obstruction plate is formed in the reaction tank of the fluidized bed biological treatment apparatus over the entire height of the tank, the carrier aggregates to form a large mass, the fluidity is lowered, and the required power is increased.

In the reaction tank without a baffle as shown in FIG. 5 described later, when the carrier has a high filling rate, the flow of the liquid in the tank is mainly laminar, so that the carrier having a specific gravity of 1.0 or less is circulated near the surface of the water, It stays along the inner circumference of the body.

For this reason, in the case of not forming an up-down obstruction plate (hereinafter sometimes referred to as a longitudinal obstruction plate) on the inner circumferential surface of the reactor, as in Patent Documents 1 and 2, the carrier which floats near the water surface of the inner circumferential surface of the reaction vessel remains, The proportion of the carrier which flows becomes small.

That is, in the case of a reaction tank without a vertical obstruction plate as in Patent Documents 1 and 2, a carrier with bubbles along with biological treatment or a nasal carrier having an original specific gravity of about 1 or less is involved in the rotation of the rotary blades. As a result of the centrifugal force and the upward flow along the inner circumferential surface of the tank, the spiral is raised along the inner circumferential surface of the tank to draw the spiral trajectory. In this way, when the carrier that has risen along the inner circumferential surface of the tank reaches the surface of the water, water flows toward the vicinity of the center of the water while turning, and then descends from the vicinity of the center of the water and sinks into the water. Since the flow of water is weak, the force for flowing the floating carrier toward the center of the water surface is weak. In addition, since the carrier is wound along the inner circumferential surface of the body, the centrifugal force of the circumference acts to press the carrier to the inner circumferential surface of the tank. In this regard, in the rotary stirring vane type reaction tanks without the vertical obstruction plates, the carriers are gathered in the vicinity of the water surface on the inner circumferential surface of the tank, so that the carrier has a low flow rate.

An object of the present invention is to provide a fluidized bed biological treatment apparatus having good fluidity of a carrier and high biological treatment efficiency.

The fluidized bed biological treatment apparatus of claim 1, wherein the carrier is filled with a carrier, and a rotor blade for agitating the carrier is disposed in the vertical direction of the tank. It is characterized in that the formation.

The fluidized bed biological treatment apparatus of claim 2, wherein the carrier has an average density of 0.96 to 1.02 g / cm 3, an average particle diameter of the carrier of 1 to 5 mm, and a carrier filling rate of 5 to 50%. It is characterized by.

The fluidized bed biological treatment apparatus of claim 3, wherein the baffle plate has a flat plate shape extending from the inner circumferential surface from the inner circumferential surface while extending in the up-down direction, and having an up-and-down level below the surface position of the baffle plate. The length H ₂ is 5 to 20% of the water depth H ₁ of the body, and the width t in the centripetal direction of the baffle plate is 5 to 20% of the diameter D ₁ of the body.

In the fluidized bed biological treatment apparatus of the present invention, when the rotary blade is rotated, the liquid in the tank flows in the radial direction and the pivot direction in the vicinity of the vertical direction of the tank by the centrifugal force and the turning force received from the rotary blade, It is divided into a turning flow directed upward and a turning flow directed downward.

The liquid which becomes the turning flow toward upward rises while turning along the inner peripheral surface of a tank, and the carrier in a liquid is released. The liquid then touches the obstruction plate, flows upward along the obstruction plate, changes direction in the centripetal direction when it reaches near the water position, and then flows in a vortex, gathers near the center portion near the water position, and then sediments and rotates. Return to the vicinity of the wing. In this way, since most of the carrier rises while turning with the rising swirl, and is released during this time, the carrier smoothly moves from the periphery near the water position (near the inner circumferential surface of the body) to the center with the swirl in the centripetal direction near the water position. It flows and then sediments with the downflow from the center part near the water surface position. In this manner, the carrier circulates well in the body, and the amount of the carrier remaining on the inner circumferential surface of the body near the water surface position is reduced, and the biological treatment efficiency is improved.

1 is a longitudinal sectional view of a fluidized bed biological treatment apparatus according to an embodiment.
FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1.
3 is a perspective perspective view schematically showing the flow of water in the fluidized bed biological treatment apparatus.
4 is a longitudinal cross-sectional view of a fluidized bed biological treatment apparatus according to Comparative Example 1. FIG.
5 is a longitudinal cross-sectional view of a fluidized bed biological treatment apparatus according to Comparative Example 2. FIG.
6 is a graph showing experimental results.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment is described with reference to drawings. 1 is a longitudinal sectional view of a fluidized bed biological treatment apparatus according to an embodiment. FIG. 2 is a horizontal sectional view taken along line II-II of FIG. 1, and FIG. 3 is a perspective perspective view schematically showing the flow of water in the fluidized bed biological treatment apparatus.

The fluidized bed biological treatment apparatus 1 includes a cylindrical body 2 having a cylindrical axial direction in a vertical direction, a drive shaft 3 disposed at an axial center position of the body 2, and a drive shaft 3. A fixed rotary blade 4, a baffle plate 5 formed only in the upper part of the inner circumferential surface of the body 2, an overflow hole 7 formed in the upper part of the body 2, and a treated water extraction trap 6; Doing. The overflow level of the overflow port 7 facing the treated water extraction trap 6 is the water surface position WL in the tank 2.

The obstruction plate 5 is a rectangular plate-like body extending in the vertical direction (vertical direction in this embodiment), and the plate surface extends from the inner circumferential surface of the body 2 toward the center of the body 2.

It is preferable that the baffle plate 5 is arrange | positioned at equal intervals in the circumferential direction of the tank 2, and the longevity is 2-8, Especially 3-6 are preferable.

The upper end of the baffle plate 5 is located above the sleeping position WL, and the lower end is located below the sleeping position WL.

The length H ₂ below the water surface position WL of the baffle plate 5 is preferably 5 to 20%, particularly 10 to 15% of the water depth H ₁ of the shell 2. In addition, when not be a flat-bottom surface of the crude product (2), the depth (H ₁₎ is the mean depth of the crude product (2).

Crude product width (t) of the centripetal direction (radial direction) of the baffle plate (5), from 5 to 20%, particularly 10 ~ 15% of the diameter (inside diameter) (D ₁₎ of the crude product (2) is preferred. Further, a crude product (2) is not a perfect cylinder, such as when the diameter different from the top and the bottom, the diameter of the crude product (2) (D ₁₎ has a diameter at the surface location (WL).

If the length H ₂ and the width t of the baffle plate 5 are smaller than the above ranges, the effect of forming the up-and-down circulation flow is low, and if the size is large, the carrier flow may be hindered.

In this embodiment, the rotary blade 4 is a flat plate shape having the plate surface in the vertical direction, and extends from the drive shaft 3 in the radial direction of the tank 2. That is, in this embodiment, two rotary vanes 4 are formed in 180 degrees opposite directions. However, three or more blades may be formed in a radial direction, and about 2-4 pieces are preferable normally.

The turning diameter D ₂ of the rotary blade 4 (the distance between the tips of the two rotary blades 4 in this embodiment) is 20 to 80%, particularly 50 of the diameter D ₁ of the shell 2. About 70% is preferable.

The rotary blade 4 is arrange | positioned near the middle of the up-down direction of the tank 2. The height of the upper edge of the rotary blade 4 (height from the bottom of the body. The same applies below) (H ₃ ) is preferably 20 to 80%, particularly about 50 to 70%, of the body depth H ₁ . The upper and lower widths H ₄ of the rotary vanes 4 are preferably 5 to 60%, particularly about 10 to 40%, of the water depth H ₁ .

The height of the lower edge of the rotary blades (4) (H ₅₎ is 20 to 80%, in particular 30 to 50% of the crude water depth (H ₁₎ is preferred.

In addition, although the rotary blade 4 is formed in only one stage in an up-down direction in this embodiment, you may be formed in two or more stages.

In the case where two or more rotary vanes are provided, the height of the upper edge of the uppermost rotary vane is in the range of H ₃ , and the height of the lower edge of the lowest rotary vane is in the range of the H ₅ , and each rotary vane The sum of the upper and lower widths may be in the range of H ₄ .

In this embodiment, although the drive shaft 3 has the structure suspended from upper direction, you may form a bearing part in the bottom face of the tank 2, and may support the lower end of the drive shaft 3 by this bearing part.

Although illustration is abbreviate | omitted, the particulate-form carrier is accommodated in this tank 2.

The carrier may be any material, but is preferably in the form of a gel of a polymer crosslinked product resistant to abrasion.

As the material resin of the gel carrier, for example, polyolefin, PVA, PEG, (poly) acrylamide, N-substituted acrylamide, (poly / meth) acrylic acid or its alkali metal salt, alginic acid, polyalkylene oxide, dimethylaminoethyl ( Meth) acrylate (DAM), diacetone alcohol (DAA), polyalkylene oxide, and the like. More specifically, sodium polyacrylate, copolymer of sodium acrylate and acrylamide, copolymer of sodium acrylate and sodium acrylamide 2-methylpropane sulfonate, terpolymer of sodium acrylate and acrylamide and sodium acrylamide 2-methylpropane sulfonate And a tertiary salt of dimethylaminoethyl (meth) acrylate or a homopolymer of quaternary ammonium or a copolymer with acrylamide and the like.

The average particle diameter of the carrier is preferably 1 mm to 5 mm, particularly preferably 1.2 mm to 3.5 mm. If smaller than this, it becomes difficult to separate the carrier and water, and when larger, the flow is obstructed.

20-50% is preferable and, as for the porosity of a support | carrier, 30-40% is especially preferable. If the porosity is low, the deposition of sludge is less, and the treatment efficiency is lowered. If the porosity is high, the gas tends to be contained.

As a density of a support | carrier, it is preferable that it is 0.96-1.02 g / cm <3> on average, and it is preferable that the density of 80% or more of carriers is 0.98-1.01 g / cm <3>, especially 0.985-1.00 g / cm <3>.

The filling amount of the carrier is preferably an amount such that the volume of the carrier is 5 to 50% relative to the volume of the reaction layer below the sleeping position (WL). If the amount of the carrier is smaller than this, the treatment efficiency is lowered, and if it is more than 50%, the stirring power becomes excessive.

The raw water (organic-containing wastewater) is supplied from the raw water supply pipe 8 into the tank 2 while the rotary vanes 4 are rotated, and biological treatment is performed.

It is preferable to adjust the rotation speed of the drive shaft 3 of the rotary blade 4 so that G value may be 100-200, and it is preferable to set it as 15-30 rpm in general.

Thus, the flow of the liquid in the tank 2 at the time of processing is demonstrated with reference to FIG.

The liquid in the tank 2 (liquid mixed with the water to be treated and the carrier) flows in the radial direction and the turning direction near the middle in the vertical direction of the tank 2 by the centrifugal force and the turning force received from the rotary vanes 4, It is divided into turning flow upward and downward turning in contact with the inner circumferential surface of (2).

The liquid is directed upwardly swirling flow is raised while turning as shown by the arrow (u ₁₎ along the inner circumferential surface of the crude product (2). During this time, the carrier in the liquid is released. The liquid then touches the obstruction plate 5, flows upward along the obstruction plate 5 as an arrow u ₂ , and reaches near the water surface position WL in the centripetal direction as shown by the arrow u ₃ . After changing the direction, it flows in a vortex shape, gathers in the vicinity of the center portion near the water surface position, then settles and returns to the vicinity of the rotary blade 4.

On the other hand, the liquid which turns into the downward flow from the vicinity of the middle in the up-down direction of the tank 2 descends while turning along the inner circumferential surface of the tank 2 as shown by the arrow d ₁ . It flows in a vortex shape as shown in (d ₂ ), gathers near the center of the bottom surface of the tank 2, and then rises around the center of the tank 2 as shown by the arrow d ₃ , and returns to the rotary blade 4.

In this embodiment, since the specific gravity of the carrier is about 1 or less, most of the carrier rises while turning along the inner circumferential surface of the tank 2 with the rising swirl flow u ₁ , and is released during this time. For this reason, it flows smoothly toward the center part from the periphery part (near the inner peripheral surface of the tank 2) near the water position, and descends from the center part near the water position WL with the vortices in the centripetal direction near the water position WL. Settles with the flow. In this way, the carrier circulates in the tank 2 satisfactorily, so that the amount of the carrier remaining on the inner circumferential surface of the tank 2 near the water surface position WL is reduced, and the biological treatment efficiency is improved.

In order to explain this effect of the present invention, Comparative Example 1 (FIG. 4) in which the baffle plate 5 was formed over the entire body height as a comparative example, and Comparative Example 2 (FIG. 5) in which the baffle plate 5 was omitted. The flow of the liquid in will be described next.

In the fluidized bed biological treatment apparatus 1A of FIG. 4, the obstruction plate 5A extends from the top of the water surface to the bottom of the tank 2.

In this comparative example 1, the liquid which flowed in the radial direction and the turning direction from the rotary blade 4 is divided into up and down after reaching the inner peripheral surface of the tank 2. Most of the carriers included in this upward flow rise along the baffle plate 5A. In this way, when the carrier does not turn and simply rises, the carriers aggregate through the carrier-adhesive biofilm to form a lump. Thus, when a carrier becomes a lump shape, a bubble collects in a large quantity between carriers, and it becomes difficult to settle.

In addition, even if a swirling swirl flow acts on the support near the water position WL, the support remains along the inner circumferential surface of the tank 2 near the water position WL without the flow. As a result, the ratio of the carrier which circulates in the tank 2 with the circulation flow in the tank 2 decreases, and biological treatment efficiency falls.

In the fluidized bed biological treatment apparatus 1B of FIG. 5, no obstruction plate is formed. In this case, the liquid flowing from the rotary blade 4 toward the inner circumferential surface of the body 2 in the radial direction and the turning direction reaches the body inner circumferential surface, and is divided into both the upper and lower sides, and then the liquid facing upward is in the case of FIGS. As it turns up, the carrier is released. However, when the carrier ascends in this way and reaches the water position, the flow velocity in the circumferential direction of the swing flow is large, so that the centrifugal force acts strongly on the carrier, so that the carrier is formed near the water position WL (2). Is pressed against the inner circumferential surface of

For this reason, also in this FIG. 5, the ratio of the carrier which circulates in the tank 2 reduces, and biological treatment efficiency becomes low.

[Example 1]

Hereinafter, an Example and a comparative example are demonstrated.

[Example 1]

The dimensions of the parts to Fig. 1 to the following: using the fluidized-bed biological treatment apparatus shown in Figure 3 was treated by feeding the liquid crystal manufacturing a multiple of the NO ₃ -N concentration 200 ㎎ / ℓ to 1.2 ㎥ / hr.

D ₁ ： 1200 mm

D ₂ ： 900 mm (4 rotary vanes)

H ₁ ： 2000 mm

H ₂ : 180 mm

H ₃ : 1180 mm

H ₄ : 360 mm

H ₅ : 820 mm

t ： 120 mm

The carrier was filled with a polyolefin gel carrier (average particle diameter 4 mm) having a density of 1.01 g / cm 3 and 30% of the bulk volume. As a result of operating the rotary vanes 4 at 20 rpm, the NO ₃ -N concentration in the treated water was 5 mg / L or less, and the N removal rate was 98% or more.

[Comparative Example 1]

As shown in Fig. 4, the blocking plate 5A is extended to the bottom of the tank ₂ , and the raw water is discharged in the same manner as in Example 1 except that the diameter D ₂ of the rotary blade 4 is 600 mm. As a result of the treatment, the concentration of NO ₃ -N in the treated water was 28 mg / L, and the N removal rate was 86%.

[Comparative example 2]

As in FIG. 5, the raw water was treated in the same manner as in Example 1 except that the obstruction plate was omitted. As a result, the NO ₃ -N concentration of the treated water was 20 mg / L, and the N removal rate was 90%. In addition, the diameter of the rotor blades (D ₂₎ is 900 ㎜ as in Example 1.

[Test that changed rotation speed of rotary vane]

In these Examples 1 and 2 and 2, the flow rate of the carrier was measured by changing the rotational speed of the rotor blades in various ways.

The flow rate of this carrier is the volume of the carrier which actually flows among the carriers filled in the tank. The volume of the carrier actually flowing was obtained by taking a carrier suspended in the water along the inner circumferential surface of the tank 2, calculating the volume, and subtracting the volume of the non-flow carrier from the total amount of the packed carrier.

This result is shown in FIG. As shown in FIG. 6, Example 1 always has a higher flow rate than Comparative Example 1, and it is recognized that the flow rate is higher than that of Comparative Example 2 when the rotor blade rotation speed is about 15 rpm or more.

[Example 2]

As a result of treating raw water in the same manner as in Example 1 except that the length H ₂ below the surface position of the baffle plate 5 was set to 100 mm (5% of the depth H ₁ ), NO ₃ of the treated water was -N concentration was 5 mg / L or less, and N removal rate was 98% or more.

EXAMPLE 3

Length less than the surface position of the baffle plate (5) (H ₂₎ the result of that one (20% of the depth (H1)) 400 ㎜ except in the same manner as in Example 1 processed the raw water, treatment of NO ₃ - N concentration was 5 mg / L or less, and N removal rate was 98% or more.

[Comparative Example 3]

The lower end of the baffle plate 5 is extended to the same level as the rotary vane 4, except that the length H ₂ below the surface position of the baffle plate is 1180 mm (59% of the water depth H ₁ ). As a result of treating raw water in the same manner as in Example 1, the NO ₃ -N concentration in the treated water was 25 mg / L, and the N removal rate was 87.5%.

As is apparent from these examples and comparative examples, according to the examples in which the baffle plate is formed only on the upper portion of the inner circumferential surface of the body, the N removal rate is higher than that of the comparative example.

1, 1A, 1B: Fluidized Bed Biological Processing Unit
2:
3: drive shaft
4: rotating wing
5, 5A: baffle plate
6: treated water trap
7: overflow sphere
8: raw water supply pipe

Claims (3)

In a fluidized bed biological treatment apparatus in which a carrier is filled in a tank, and a rotary vane for stirring the carrier is disposed in the middle of the tank in the vertical direction.
Forming a baffle only on the upper part of the inner circumference of the body,
The baffle plate has a flat plate shape extending in the up-down direction and extending in the centripetal direction from the inner circumference of the body,
And a vertical length less than the surface position of the baffle plate (H ₂₎ from 5 to 20% of the depth (H ₁₎ of a crude product,
The width t in the centripetal direction of the baffle plate is 5 to 20% of the diameter D _{1 of the} tank. The method of claim 1,
A fluidized bed biological treatment apparatus characterized in that the average density of the carrier is 0.96 to 1.02 g / cm 3, the average particle diameter of the carrier is 1 to 5 mm, and the filling rate of the carrier in the body is 5 to 50%. delete

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