JP3074609B2 - Circulating fluidized bed processing tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circulating fluidized bed processing tank for purifying water by circulating water containing bioparticles in a reactor.

[0002]

2. Description of the Related Art Conventionally, various wastewater treatment apparatuses have been developed and provided to prevent water pollution in seawater, rivers, lakes and marshes. As one of such wastewater treatment apparatuses, there is an apparatus using a circulating fluidized bed treatment tank. FIG. 6 shows an example of the circulating fluidized bed type processing tank.
Such a circulating fluidized bed type treatment tank 10 is aerated at the bottom of the inner cylinder 14 by an aeration device 15, and the wastewater and bioparticles (particles having a microbial membrane formed on the surface) are separated in the reactor 12 by an airlift effect in the direction of the arrow. It purifies by the microorganism purifying action of bioparticles while circulating and flowing. Then, the wastewater injection device 25 injects new wastewater, thereby purifying the bioparticles while aerating them by the action of particles in which a biofilm has grown on the surface of the bioparticle particles or particles containing a microorganism in a polymer gel or the like. The separation section separates the bioparticles and the treated water containing suspended sludge, and the treated water naturally flows out to the settling tank 10 together with the suspended sludge.

[0003] In order to keep the bioparticles separated from the sludge in the circulating fluidized bed type treatment tank 10 at all times, the bioparticle separation unit 11 separates the wastewater in which the bioparticles and the sludge are mixed by gravity ( The specific gravity of bioparticles is greater than the specific gravity of sludge), reactor 1
The sludge generated in the bio-particle separation unit 11 is a water stream (waste water injection from the waste water injection device 25, the bio-particle separation unit 11).
The bioparticle separating unit 11 is raised on the water flow flowing from below to the overflow weir 19) and flows out of the overflow weir 19 into the sedimentation tank 10, while the bioparticles are settled by their own weight (the speed of the water flow is Lower than the settling velocity of bioparticles and higher than the settling velocity of sludge.)

[0004] Therefore, when the speed of the water flow in the bioparticle separation section 11 is low, the sludge also settles, and the sludge properties become high in viscosity, and the bioparticle separation section 1
In step 1, a sludge blanket (sludge layer) is generated. Further, when the microbial membrane of the bioparticles becomes thicker and the bioparticles become lighter and the sedimentation speed becomes slower, a sludge blanket is similarly generated at the lower portion of the bioparticle separation unit 11.

[0005] The production of such a sludge blanket has the following problems. The problem is that sedimentation of bioparticles becomes difficult and sludge rises difficult, so it becomes difficult to separate bioparticles and sludge. The sludge adhering to the surface of the bioparticles intercepts the gas and floats with the bioparticles included therein, and the bioparticles are not well separated and flow out from the circulating fluidized bed type treatment tank 10 to the precipitation tank P. Therefore, there is a problem that the amount of bioparticles in the reactor 12 is reduced, the treatment capacity is reduced, and wastewater treatment becomes impossible (it is very difficult to selectively separate bioparticles once flowing into the settling tank P from sludge). . The sludge blanket partially floats as scum on the upper part of the bioparticle separation section 11, flows into the sedimentation tank P from the overflow weir 19, floats again as scum in the sedimentation tank P, and mixes into the treated water. The problem is that water quality deteriorates.

In order to solve the above problem, it is only necessary to prevent sludge blanket from being generated. In order to prevent the formation of a sludge blanket, the following method can be considered in principle. That is, a flow velocity larger than the sedimentation velocity of the sludge and smaller than the sedimentation velocity of the bioparticles shown in FIG. 6 is given to the bioparticle separation unit 11 (the sedimentation velocity shown in FIG. The experimental values at the plant were not much different from this.)

[0007] However, even when designing based on such a concept, a sludge blanket may be generated and the above problem may occur. This is likely to occur when wastewater with properties and concentrations different from the design conditions flows in or when the amount of inflow water differs from the plan, which is common after the construction of wastewater treatment facilities.

As a countermeasure for this, one method is to destroy the sludge blanket, or to adjust the flow velocity of the bioparticle separation section 11 so as not to generate a sludge blanket.

Therefore, the present inventor has conceived of a method of increasing the flow velocity of the bioparticle separation section 11 so that a sludge blanket cannot be formed, and a method of destroying the sludge blanket by causing local flow and drift in the sludge blanket. did.

[0010] The invention of claim 1 has been made in view of such circumstances, and an object thereof is to provide a circulating fluidized bed type processing tank which does not generate a sludge blanket in a bioparticle separation section. The point is to provide.
Another object of the present invention is to provide a circulating fluidized bed treatment tank capable of destroying a sludge blanket generated in a bioparticle separation section.

[0011]

The gist of the present invention is to provide a reactor for storing wastewater containing microorganism-adhered particles having microorganisms attached to a surface thereof, circulating the wastewater in the reactor, Aeration means for ejecting a gas for supplying oxygen to the microorganisms, and microorganism-adhered particle separation formed on the upper portion of the reactor and communicating with the reactor, which separates sludge and microorganism-adhered particles by gravity using a difference in specific gravity. A circulating fluidized bed treatment tank for purifying wastewater by utilizing the purification action of the microorganisms, wherein the separation means is provided with expansion / contraction means. Exists in a fluidized bed type treatment tank.

[0012] The gist of the invention according to claim 2 is that a reactor for storing wastewater containing microorganism-adhered particles having microorganisms attached to the surface thereof, and that the wastewater in the reactor is circulated and oxygen is supplied to the microorganism. Aeration means for ejecting gas to be blown off, and a microorganism-adhered particle separation unit formed at the upper part of the reactor, which communicates with the reactor, and separates sludge and microorganism-adhered particles by gravity using a difference in specific gravity by gravity. Further, there is provided a circulating fluidized bed type treatment tank for purifying wastewater by utilizing the purifying action of the microorganisms, wherein a swelling means is provided above the reactor.

[0013] The gist of the invention according to claim 3 is to provide a reactor for storing wastewater containing microorganism-adhered particles having microorganisms attached to the surface thereof, circulating the wastewater in the reactor, and supplying oxygen to the microorganisms. Aeration means for ejecting gas to be blown off, and a microorganism-attached particle separation unit formed at the upper part of the reactor, which communicates with the reactor, and separates sludge and microorganism-attached particles by gravity using a difference in specific gravity by gravity. A circulating fluidized bed treatment tank for purifying wastewater by utilizing the purification action of the microorganisms, wherein an overflow site and an overflow weir of a treated water discharge overflow weir are provided above the microorganism-attached particle separation unit; The present invention resides in a circulating fluidized bed type processing tank characterized in that a drainage means having a means for adjusting the total length or a means for adjusting the flow rate in each overflow weir is provided.

[0014]

The expansion / contraction means according to the first aspect of the present invention, when expanded, reduces the actual volume of the microorganism-adhered particle separation section, narrows the flow path, and increases the speed of the treated water flowing through the microorganism-adhered particle separation section. (Q = AV = const) to prevent sludge blanket formation.

According to the second aspect of the present invention, the expansion and contraction means reduces the substantial volume of the upper part of the reactor when expanded, and the air bubbles which have not been completely destroyed at the upper part of the reactor flow down in a circulating flow to separate microorganism-adhered particles. The number of bubbles reaching the section increases, and the airflow flowing into the microorganism-adhered particle separation section increases, and the bubbles destroy the sludge blanket.

According to a third aspect of the present invention, the drainage means comprises a drainage means for increasing the drainage of only a part of the drainage means.
The existing sludge blanket near the drainage means is destroyed, and thus the entire sludge blanket is destroyed (a part of the sludge blanket, when partially destroyed, has the property of leading to total destruction).

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the present embodiment are not intended to limit the scope of the present invention only to them unless otherwise specified. , Are merely illustrative examples.

(Embodiment 1) A circulating fluidized bed type processing tank 10 according to Embodiment 1 will be described with reference to FIGS. Example 1 relates to the first aspect of the present invention, and is intended to prevent generation of a sludge blanket.

As shown in FIG. 1, the circulating fluidized bed type processing tank 10 is a cylindrical body whose upper part swells in the horizontal direction, and the swelling part forms the bioparticle separation part 11 and the remaining part. The part forms the reactor 12.

The reactor 12 is a cylindrical body roughly constituted by an outer cylinder 13 and an inner cylinder 14 concentric with the outer cylinder 13 inside the outer cylinder 13. Bioparticles (particles adhering to microorganisms) are formed. The wastewater W containing is stored. Bioparticles are particles having a microbial membrane formed on the surface, and have a wastewater purifying action.

The reactor 12 is provided with an aeration device 15 comprising an air ejection section 16 located at the inner bottom of the reactor 12 and a pump 17 for sending air to the air ejection section 16. The aeration device 15 circulates the wastewater W and ejects air for supplying oxygen to microorganisms generated on the surface of the bioparticle.

The bio-particle separation section 11 communicates with the reactor 12 and separates sludge and bio-particles by gravity using a difference in specific gravity. An L-shaped flange 26 is provided with a portion corresponding to the L-shaped vertical bar portion facing upward, and the groove 18 is formed by the flange 26 and the outer cylinder 13. A plurality of overflow weirs 19 are provided above the flange 26 at equal intervals in the circumferential direction. Therefore, the treated water treated in the circulating fluidized bed treatment tank 10 flows from the overflow weir 19 into the groove 18 and flows into the sedimentation tank (not shown) from the groove 18. The reactor 12 is separated from the reactor 12 by a bottomless cylindrical partition wall 20, and an overflow weir 19 is formed at the upper end.

Further, in the first embodiment, the bioparticle separating section 11 is provided with expansion / contraction means 21. The expansion / contraction means 21 includes an expansion / contraction section 22 and a compressor 23 for blowing air to the expansion / contraction section 22. As shown in FIG. 1, the expanding / contracting portion 22 has one edge portion at a portion of the flange 26 corresponding to an L-shaped corner portion in a longitudinal sectional view,
An annular body made of rubber and having the other edge portion fixed to the inner wall of the outer cylinder 13. As a material, chloroprene synthetic rubber, other synthetic rubbers, natural rubbers, and other elastomers having flexibility, water resistance, and corrosion resistance and suitable for practicing the present invention can be used.

A sludge densitometer 24 is provided at the expected sludge blanket generation area A, that is, at a plurality of locations on the outer surface of the partition wall 20. As the sludge concentration meter 24, a device suitable for practicing the present invention, such as a device for detecting turbidity based on light transmittance or the like, can be used.

Next, the operation of the circulating fluidized bed processing tank 10 configured as described above will be described. The sludge concentration meter 2
Numeral 4 measures the turbidity and displays it on a display unit (not shown).

When the operator determines that a sludge blanket is being generated based on the turbidity, the operator operates the compressor 23 to expand the expansion / contraction section 22. The degree of expansion is determined in consideration of the size of the carrier particles, the thickness of the microorganism film, the amount of water injected from the drainage injection device 25, and the like. FIG. 5 shows the relationship between the size of the carrier particles, or the thickness of the microbial membrane, and the sedimentation velocity of the bioparticles.

When the expansion / contraction section 22 expands, the actual volume of the bioparticle separation section 11 is reduced, the flow path is narrowed, and the speed of the treated water flowing through the bioparticle separation section 11 is increased (Q = AV = const). ).

Next, the effects of the circulating fluidized bed type processing tank 10 configured as described above will be described. According to the circulating fluidized bed treatment tank 10, by expanding the expansion / contraction section 22, the flow rate of the sludge blanket separation section 11 (the velocity of the water flow from below the sludge blanket separation section 11 to the overflow weir 19). ) Can be increased, so that the generation of a sludge blanket can be prevented. As a result, the disadvantage that the bioparticles are not separated from the sludge and flow out of the circulating fluidized bed treatment tank 10 and that the quality of the treated water deteriorates can be solved, and this point has been experimentally demonstrated. .

In this embodiment, the operation of the compressor 23 is manually performed. However, the scope of the present invention is not limited to this. In the present invention, the measurement signal from the sludge concentration meter 24 is a predetermined signal. The compressor 23 may be operated when the threshold value is exceeded.

(Embodiment 2) First, the configuration of a circulating fluidized bed type processing tank according to Embodiment 2 will be described with reference to FIG. Embodiment 2 relates to the second aspect of the present invention, in which a sludge blanket produced is destroyed.

A circulating fluidized bed type processing tank 30 according to the second embodiment.
Has substantially the same configuration as that according to the first embodiment. However, the expansion / contraction means 31 is provided not in the bioparticle separation section 11 but in the upper portion of the reactor 12. More specifically, as shown in FIG. 2, the upper and lower edges are fixed to the inner surface of the partition wall 20 so that the upper edge is in contact with the water surface. is there.
Note that the same components as those of the circulating fluidized bed type processing tank 10 according to the first embodiment are denoted by the same reference numerals.

Next, the operation of the circulating fluidized bed type processing tank 30 configured as described above will be described. Sludge concentration meter 24
When the operator determines that a sludge blanket has occurred in the bioparticle separation unit 11, air is supplied from the compressor 33 to expand the expansion / contraction unit 32,
The volume at the top of the reactor 12 is reduced. The degree of expansion, as in Example 1, is determined in consideration of the size of the carrier particles, the thickness of the microbial membrane, the amount of water injected from the drainage injection device 25, and the like.

When the volume of the upper part of the reactor 12 decreases, the air bubbles that have not been destroyed at the upper part of the reactor 12 flow along the circulation flow between the outer surface of the inner cylinder 14 and the inner surface of the partition 20. Therefore, the number of bubbles reaching the communication part B with the reactor 12 increases, and as a result, the number of bubbles flowing into the bioparticle separation unit 11 increases, and the water flow generated by the rise of the bubbles (from the communication part B toward the water surface) The flow) destroys the sludge blanket.

Next, the effects of the circulating fluidized bed type processing tank 30 configured as described above will be described. According to the circulating fluidized bed processing tank 30, the sludge blanket generated by expanding the expansion / contraction section 32 can be destroyed. As a result, the disadvantage that the bioparticles flow out of the treatment tank 30 without being separated from the sludge, and the disadvantage that the quality of treated water deteriorates, and the like can be solved. This point has also been experimentally verified as in the first embodiment.

The expansion and contraction of the expansion and contraction portion 32 is described below.
Display unit (not shown) of the sludge concentration meter 24 as in the first embodiment.
By a worker, or by a method suitable for carrying out the present invention, such as operating the compressor 33 when the measurement signal from the sludge concentration meter 24 exceeds a predetermined threshold. Can be.

(Embodiment 3) First, the configuration of a circulating fluidized bed type processing tank according to Embodiment 3 will be described with reference to FIGS. The third embodiment relates to the third aspect of the present invention, in which a sludge blanket produced is destroyed.

A circulating fluidized bed type processing tank 40 according to the third embodiment.
Has substantially the same configuration as that according to the first embodiment. However, no overflow means is provided, but instead, as shown in FIG. 3, a weir plate 42 (see FIG. A plurality of flow control means for each overflow weir are provided.
Each of the weir plates 42 can be individually raised and lowered as shown in FIG. In addition, as the lifting / lowering means (not shown), a means suitable for carrying out the present invention, such as a means using a fluid pressure, an electric motor, or a manual means, can be used. In addition, overflow overflow weirs are provided on the entire circumference, and some overflow overflow weirs are blocked by the same means as described above, so that overflow overflow occurs only from a part (for example, a plurality of equally spaced overflow weirs). By adjusting the flow site and the total length of the overflow weir, a local flow can be generated and the sludge blanket can be destroyed. In addition, the circulating fluidized bed processing tank 10 according to the first embodiment
The same reference numerals are given to the same constituent members as in.

Next, the operation of the circulating fluidized bed processing tank 40 configured as described above will be described. The weir plate 42
Changes the amount of water flowing over each overflow weir by ascending and descending. When the weir plate 42 is lowered, the overflow amount increases compared to before the lowering (

(Equation 1) Q _i : overflow weir C: flow coefficient h: head of overflow weir 41 y: depth from free surface x: width of overflow weir 41 at depth y, function of h). In the overflow weir where the overflow weir is deep (h is large), the overflow increases, and the bioparticle separation unit 1 around the overflow weir is increased.
1, the flow rate from below toward the overflow weir 41 increases. As a result, the speed of the water flow from below toward the overflow weir 41 is increased. ΣQ _i = Q (constant)

That is, the weir plate 42 of one overflow weir 41 or two or three adjacent overflow weirs 41 is lowered, and the remaining weir plates 42 of the overflow weir 41 are raised. In this case, a local flow is generated,
The flow velocity of the water flow in the vicinity of the portion where the water flow is lowered is increased.

As in the first embodiment, the degree to which the weir plate 42 is lowered is determined by the size of the carrier particles, the thickness of the microbial membrane, and the size of the wastewater injection device (not shown in FIGS. 4 and 5). Determined taking into account the amount of water injected.

Next, the effect of the circulating fluidized bed type processing tank 40 configured as described above will be described. Since the speed of the water flow from below to the overflow weir 41 is increased, the sludge blanket generated in the bioparticle separation unit 11 can be destroyed.

Further, the sludge blanket can be locally destroyed by the local flow, and thus the entire sludge blanket can be destroyed. (When the sludge blanket is destroyed and partially destroyed, it is effectively destroyed. Has the property to lead to).

As a result, the disadvantage that the bioparticles are not separated from the sludge and flow out from the circulating fluidized bed type treatment tank 40, and that the quality of the treated water deteriorates, and the like can be eliminated. This point has also been experimentally verified as in the first embodiment.

The lifting and lowering of the weir plate 42 is performed by an operator, as in the first embodiment, by looking at the display of a sludge concentration meter (not shown), or when a measurement signal from the sludge concentration meter is a predetermined signal. When the threshold value is exceeded, the barrier plate 42 may be lowered, for example, by a method suitable for carrying out the present invention.

Further, although the weir plate 42 is raised and lowered, it is not intended to limit the scope of the present invention thereto. In the present invention, for example, the width of the overflow weir 41 is changed. Such as those that move in the horizontal direction as described above can be used in practicing the present invention.

Although the overflow weir 41 is a square weir, it is not intended to limit the scope of the present invention to it. In the present invention, other weirs such as a triangular weir, a trapezoidal weir, a circular weir, etc. A weir of a suitable shape can be used for carrying out the present invention.

Although the overflow weir 41 is used as the drainage means, the scope of the present invention is not limited to the overflow weir 41. In the present invention, other drainage means, such as an orifice, may be used to carry out the present invention. And a suitable drainage means can be used.

[0048]

The present invention has the following effects because it is configured as described above. The expansion / contraction means according to the first aspect of the present invention reduces the actual volume of the microorganism-adhered particle separation unit when expanded, narrows the flow path, and increases the speed of the treated water flowing through the microorganism-adhered particle separation unit. Blanket formation can be prevented.

The expansion / contraction means according to the second aspect of the present invention reduces the substantial volume of the upper part of the reactor when expanded,
Bubbles that could not be destroyed at the top of the reactor flow down along the circulating flow, the number of bubbles reaching the microbe-attached particle separation section increases, and the airflow flowing into the microbe-attached particle separation section increases, which destroys the sludge blanket I do. Also,
The drainage means for the flow rate adjusting means according to the invention of claim 3 is:
Increasing the drainage of only some of the drainage means destroys the sludge blanket near the drainage means, and eventually destroys the entire sludge blanket. is there). As a result, according to the first, second, and third aspects of the present invention, it is possible to eliminate the disadvantage that the bioparticles flow out of the treatment tank without being separated from the sludge and that the quality of the treated water deteriorates.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a circulating fluidized bed processing tank according to a first embodiment.

FIG. 2 is a schematic configuration diagram of a circulating fluidized bed processing tank according to a second embodiment.

FIG. 3 is a plan view of a circulating fluidized bed processing tank according to a third embodiment.

FIG. 4 is a perspective view of a flow rate adjusting means provided in an overflow weir relating to the circulating fluidized bed type processing tank.

FIG. 5 is a diagram showing the relationship between the particle size of bioparticles and the sedimentation velocity.

FIG. 6 is a schematic configuration diagram of a circulating fluidized bed type processing tank according to a conventional example.

[Explanation of symbols]

 W Wastewater 10 Circulating fluidized bed treatment tank 11 Bioparticle separation unit 12 Reactor 15 Aerator 21 Expansion / contraction means 22 Expansion / contraction part 23 Compressor 30 Circulating fluidized bed treatment tank 31 Expansion / contraction means 32 Expansion / contraction part 33 Compressor 40 Circulating fluidized bed Die treatment tank 41 Overflow weir 42 Weir plate (flow control means)

Claims (3)

(57) [Claims] 1. A reactor for storing wastewater containing microorganism-adhered particles having microorganisms adhered to a surface thereof, and aeration means for circulating the wastewater in the reactor and jetting a gas for supplying oxygen to the microorganisms. A microbial-adhered particle separating section formed at the upper portion of the reactor, communicating with the reactor, and separating sludge and microbial-adhered particles by gravity using a difference in specific gravity, utilizing the purification action of the microorganisms. A circulating fluidized bed treatment tank for purifying wastewater by means of a circulating fluidized bed treatment tank, wherein a swelling means is provided in the microorganism attached particle separation section. 2. A reactor for storing wastewater containing microorganism-adhered particles having microorganisms adhered to the surface thereof, and aeration means for circulating the wastewater in the reactor and jetting a gas for supplying oxygen to the microorganisms. A microbial-adhered particle separating section formed at the upper portion of the reactor, communicating with the reactor, and separating sludge and microbial-adhered particles by gravity using a difference in specific gravity, utilizing the purification action of the microorganisms. A circulating fluidized bed treatment tank for purifying wastewater by means of a circulating fluidized bed treatment tank, wherein a swelling means is provided above the reactor. 3. A reactor for storing wastewater containing microorganism-adhered particles having microorganisms adhered to the surface thereof, and aeration means for circulating the wastewater in the reactor and jetting a gas for supplying oxygen to the microorganisms. A microbial-adhered particle separating section formed at the upper portion of the reactor, communicating with the reactor, and separating sludge and microbial-adhered particles by gravity using a difference in specific gravity, utilizing the purification action of the microorganisms. A circulating fluidized bed treatment tank for purifying wastewater by means of means for adjusting the overflow site and the overall length of the overflow weir for treated water discharge above the microorganism-adhered particle separation unit, or each overflow. A circulating fluidized bed treatment tank comprising a weir provided with drainage means having means for adjusting a flow rate.