JP2014097480A - Activated sludge treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an activated sludge treatment apparatus which suppresses the increase of power consumption, also prevents the breaking of a floc, and efficiently dissolves a gas in an activated sludge containing liquid.SOLUTION: The activated sludge treatment apparatus comprises: a porous tube 160 which is formed of a porous body having a plurality of pores, and circulates an activated sludge containing liquid therein which is a liquid containing activated sludge; a gas introduction part 180 which introduces a gas into the activated sludge containing liquid through the plurality of pores from the outside of the porous tube 160; and a rotation device 170 which rotates the porous tube 160 while setting an axis A of the porous tube 160 as a rotational axis.

Description

  The present invention relates to an activated sludge treatment apparatus for treating wastewater with activated sludge.

  A technique (activated sludge method) for purifying treated water such as sewage and wastewater with activated sludge (microorganisms) is known. The process for performing the activated sludge method includes an aeration tank (reaction tank) and a precipitation tank. In the aeration tank, oxygen is dissolved in the liquid by aeration of the liquid containing activated sludge and water to be treated. In the aeration tank, activated sludge uses dissolved oxygen to oxidize and decompose pollutants in the water to be treated.

  Conventionally, since air bubbles having a particle diameter of about 2 mm have been introduced into the aeration tank, the oxygen dissolution efficiency is low, and enormous power is required for aeration. For example, when all sewage in Japan is treated by the activated sludge method, it is said that the power required for aeration accounts for about 1% of the total power consumption in Japan.

  Therefore, in order to reduce the power consumption required for aeration, bubbles having a particle size of the order of micrometers (hereinafter referred to as “microbubbles”) are introduced into the aeration tank, thereby increasing the specific surface area of the bubbles and dissolving oxygen. A method for improving the efficiency can be considered.

  As an apparatus that generates microbubbles, for example, there is an apparatus that generates microbubbles by applying a strong shearing force to bubbles larger than the microbubbles to finely tear the bubbles. When a microbubble generator using this shearing force is applied to an aeration tank, activated sludge aggregates (floc) are destroyed by the shearing force. In the activated sludge method, in order to separate the purified liquid (treated water) and activated sludge by using the floc sedimentation in the sedimentation tank, if the floc is destroyed, the activated sludge and treatment in the sedimentation tank Separation from water becomes difficult.

  Therefore, in recent years, a sealed chamber formed of a porous body is installed in a liquid containing activated sludge (hereinafter referred to as “activated sludge-containing liquid”), and compressed gas is supplied from the inside of the sealed chamber. A technique for introducing microbubbles into an activated sludge-containing liquid is disclosed (for example, Patent Document 1). In the technique of Patent Document 1, the bubbles introduced from the pores of the porous body are torn off by the flow of the activated sludge-containing liquid flowing outside the porous body, thereby generating microbubbles. Therefore, compared with the microbubble generator using the shearing force, the breakage of the floc can be suppressed.

JP 2012-135741 A

  In the technique of Patent Document 1 described above, it is necessary to increase the flow velocity of the liquid flowing outside the porous body as the particle size of the generated bubbles is reduced. If it does so, the motive power of the pump for forming the flow of activated sludge containing liquid must be enlarged, and not only the structure of a pump will become a big scale but power consumption will increase. Moreover, if the flow rate of the activated sludge-containing liquid is increased too much, the flocs may be destroyed.

  Therefore, an object of the present invention is to provide an activated sludge treatment apparatus capable of efficiently dissolving a gas in an activated sludge-containing liquid while suppressing an increase in power consumption and suppressing breakage of flocs.

  In order to solve the above-mentioned problem, an activated sludge treatment apparatus of the present invention is formed of a porous body having a plurality of pores, a porous tube through which an activated sludge-containing liquid, which is a liquid containing activated sludge, circulates, A gas introduction part that introduces gas into the activated sludge-containing liquid from the outside of the porous tube through a plurality of holes, and a rotating device that rotates the porous tube around the axis of the porous tube as a rotation axis To do.

  The activated sludge treatment apparatus includes a storage tank that stores the activated sludge-containing liquid, and a connecting pipe that is connected to the storing tank. The rotating device has one end fixed to the porous pipe and the other end connected to the connecting pipe. The rotating tube connected to be rotatable and a drive unit that rotates the rotating tube may be included, and the diameter of the porous tube may be larger than the diameter of the rotating tube.

  The rotating device may rotate the porous tube in a predetermined rotation direction, and then rotate the porous tube in a rotation direction opposite to the predetermined rotation direction.

  A vibration device that linearly vibrates the porous tube may be further provided.

  In order to solve the above problems, another activated sludge treatment apparatus of the present invention is formed of a porous body having a plurality of holes, and a porous tube through which an activated sludge-containing liquid, which is a liquid containing activated sludge, flows. And a gas introduction part for introducing gas into the activated sludge-containing liquid from the outside of the porous tube through a plurality of holes, and a vibration device for linearly vibrating the porous tube.

  According to the present invention, it is possible to efficiently dissolve the gas in the activated sludge-containing liquid by suppressing the breakage of flocs while suppressing an increase in power consumption.

It is a figure for demonstrating the activated sludge processing apparatus concerning 1st Embodiment. It is a figure for demonstrating the specific structure of the microbubble generating part concerning 1st Embodiment. It is the elements on larger scale of a porous tube. It is a figure for demonstrating the activated sludge processing apparatus concerning 2nd Embodiment. It is a figure for demonstrating the specific structure of the microbubble generating part concerning 2nd Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(First embodiment)
FIG. 1 is a diagram for explaining an activated sludge treatment apparatus 100 according to the first embodiment. As shown in FIG. 1, the activated sludge treatment apparatus 100 includes a storage tank 110, connecting pipes 120 a and 120 b, a pump 122, and a microbubble generator 150.

  The storage tank 110 is a tank for storing an activated sludge-containing liquid that is a liquid containing activated sludge. The storage tank 110 is supplied with water to be treated such as sewage and wastewater, and the pollutants contained in the water to be treated are oxidized and decomposed by activated sludge.

  One end side of the connecting pipe 120 a is connected to the storage tank 110, and the other end side is connected to the rotating pipe 172 a of the microbubble generator 150. The connecting tube 120b has one end connected to the storage tank 110 and the other end connected to the rotating tube 172b of the microbubble generator 150. Since the rotary pipes 172a and 172b are fixed to the porous pipe 160, the connecting pipe 120a, the rotary pipe 172a, the porous pipe 160, the rotary pipe 172b, and the connecting pipe 120b provide a circulation path through which the activated sludge-containing liquid flows. Will be formed.

  The connecting pipe 120a is provided with a pump 122. By driving the pump 122, the activated sludge-containing liquid stored in the storage tank 110 passes through the circulation path and is temporarily out of the storage tank 110. After being sent out, it is introduced again into the storage tank 110. Thereby, the activated sludge containing liquid will circulate.

  The microbubble generator 150 provided on the downstream side of the pump 122 introduces microbubbles into the activated sludge-containing liquid.

  FIG. 2 is a diagram for explaining a specific configuration of the microbubble generator 150 according to the first embodiment. As shown in FIG. 2, the microbubble generating unit 150 includes a porous tube 160, a rotating device 170, and a gas introducing unit 180.

  The porous tube 160 is a tube formed of a porous body having a plurality of holes. The pore diameter of the porous tube 160 is, for example, about several μm to several hundred μm. An example of the porous body is shirasu porous glass (SPG). SPG is a kind of inorganic porous material manufactured using shirasu (white sand, Hakushu), lime, and boric acid as raw materials, and is a material that can appropriately set the pore diameter.

  The rotating device 170 rotates the porous tube 160 about the axis A of the porous tube 160 (indicated by the alternate long and short dash line in FIG. 2) as the rotation axis. More specifically, the rotating device 170 includes rotating tubes 172a and 172b and a driving unit 176.

  One end side of the rotating tube 172a is fixed to the porous tube 160, and the other end side is rotatably connected to the connecting tube 120a. One end side of the rotating tube 172b is fixed to the porous tube 160, and the other end side thereof is rotatably connected to the connecting tube 120b. More specifically, a flange 172c is formed on one end side of the rotary tubes 172a and 172b, and the flange 172c is fixed to the porous tube 160 by an O-ring 172d and a fastening member 172e. Thus, the fastening member 172e fastens the flange 172c together with the O-ring 172d, so that the air-tightness of the flange 172c is maintained by the O-ring 172d. The other ends of the rotary tubes 172a and 172b are rotatably connected to the outer tube 182 by a seal bearing 174a and are rotatably connected to the connecting tubes 120a and 120b by the seal bearing 174b.

  The drive unit 176 includes an endless belt 176a stretched around a gear 172f provided on the rotary tube 172b, a pulley 176b around which the belt 176a is stretched, and a motor 176c connected to the pulley 176b. Composed. Therefore, when the motor 176c is driven to rotate, the rotating tube 172b rotates through the pulley 176b, the belt 176a, and the gear 172f, and accordingly, the porous tube 160 and the rotating tube 172a fixed to the rotating tube 172b. Will rotate. In the present embodiment, the case where the belt 176a is stretched around the gear 172f provided on the rotating tube 172b has been described as an example. However, the rotating tube 172a is provided with a gear, and the belt 176a is attached to the gear. It may be stretched. In the present embodiment, the driving unit 176 rotates the porous tube 160 at a rotational speed of 60 rpm to 2000 rpm, for example.

  The gas introduction unit 180 includes an outer pipe 182 and a compressor 184 (see FIG. 1) that introduces compressed gas into the outer pipe 182. When compressed gas (for example, compressed air) is introduced into the outer pipe 182 by the compressor 184, the compressed gas passes through the plurality of holes from the outside of the porous pipe 160 and becomes an activated sludge-containing liquid that circulates in the porous pipe 160. be introduced. In the present embodiment, the pressure of the compressed gas introduced by the compressor 184 is, for example, about 0.3 MPa.

  FIG. 3 is a partially enlarged view of the porous tube 160. As shown in FIG. 3, a plurality of holes 160 a are formed in the porous tube 160. When the compressor 184 introduces the compressed gas into the outer tube 182, the compressed gas introduced into the outer tube 182 is introduced into the porous tube 160 through the hole 160a. Since the activated sludge containing liquid is circulated in the porous tube 160 by the pump 122 (the flow direction is indicated by a white arrow in FIG. 3), the gas introduced through the hole 160a is the activated sludge containing liquid. Torn into bubbles and dispersed in the activated sludge-containing liquid.

  Here, the smaller the particle size of the generated bubbles, the larger the specific surface area of the bubbles and the better the gas dissolution efficiency. The activated sludge uses dissolved oxygen in the activated sludge-containing liquid to oxidatively decompose the pollutants in the water to be treated. Therefore, it is preferable to disperse as small bubbles as possible in the activated sludge-containing liquid. Therefore, it is conceivable to increase the flow rate of the activated sludge-containing liquid to reduce the particle size of the bubbles (to make microbubbles). However, increasing the flow rate of the activated sludge-containing liquid increases the power consumption of the pump 122. End up. Moreover, if the flow rate of the activated sludge-containing liquid is increased too much, the flocs may be destroyed.

  Therefore, returning to FIG. 2, in the microbubble generator 150 of the present embodiment, the rotating device 170 rotates the porous tube 160 about the axis A as a rotation axis. In other words, the rotating device 170 rotates the porous tube 160 in a direction orthogonal to the flow direction of the activated sludge-containing liquid. Then, the porous tube 160 (hole 160a) and the activated sludge-containing liquid are relatively moved in a direction orthogonal to the flow direction of the activated sludge-containing liquid, and the gas introduced through the hole 160a is easily torn off. . Thereby, when the flow rates of the activated sludge-containing liquid are equal, it is possible to generate bubbles having a smaller particle diameter as compared with bubbles formed by tearing only with the flow of the activated sludge-containing liquid.

  Therefore, by rotating the porous tube 160 while suppressing the flow rate of the activated sludge-containing liquid to such an extent that the floc is not destroyed, the increase in the power consumption of the pump 122 is suppressed, and the destruction of the floc is suppressed. Small bubbles (microbubbles) can be dispersed in the activated sludge-containing liquid.

  In the present embodiment, the gas introduction unit 180 introduces compressed gas from the outside to the inside of the porous tube 160. Accordingly, the porous tube 160 is always pressurized from the outside, and the durability of the porous tube 160 can be improved as compared with the case where the compressed gas is introduced from the inside of the porous tube 160. Moreover, compared with the case where compressed gas is introduce | transduced from the inside of the porous pipe | tube 160, the film thickness of the porous pipe | tube 160 can also be made small and it becomes possible to reduce the cost of the porous pipe | tube 160. FIG.

  Furthermore, in this embodiment, the diameter P of the porous tube 160 is larger than the diameter R of the rotary tubes 172a and 172b (see FIG. 2). With this configuration, the pressure loss in the porous tube 160 can be reduced compared to the configuration in which the diameter P of the porous tube 160 is substantially equal to the diameter R of the rotary tubes 172a and 172b, and the consumption of the pump 122 is reduced. Electric power can be reduced. In addition, since the pressure loss is reduced, it is possible to suppress the breakage of the floc in the porous tube 160.

  Furthermore, by making the diameter P of the porous tube 160 larger than the diameter R of the rotating tubes 172a and 172b, the diameter P of the porous tube 160 is compared with a configuration that is substantially equal to the diameter R of the rotating tubes 172a and 172b. As a result, the surface area of the porous tube 160 increases. When the flow rate per unit time of the activated sludge-containing liquid introduced from the connecting pipe 120a and delivered from the rotary pipe 172b is constant, the diameter P of the porous pipe 160 is substantially equal to the diameter R of the rotary pipes 172a and 172b. The flow rate of the activated sludge-containing liquid flowing through the porous tube 160 is smaller than that of the configuration equal to Therefore, the number of bubbles dispersed in the activated sludge-containing liquid can be increased by increasing the surface area of the porous pipe 160 and decreasing the flow rate of the activated sludge-containing liquid flowing through the porous pipe 160.

  Further, the rotating device 170 according to the present embodiment rotates the porous tube 160 in a predetermined rotation direction (forward direction), and then rotates in a direction opposite to the predetermined rotation direction (reverse direction). Rotate to When the rotating device 170 always keeps rotating the porous tube 160 in the same direction, the activated sludge-containing liquid in the porous tube 160 also rotates together with the porous tube 160, and the porous tube 160 and the activated sludge-containing liquid are separated. The relative movement stops. Therefore, the rotating device 170 rotates the porous tube 160 alternately in the forward direction and the reverse direction (for example, 10 ° in the forward direction and 10 ° in the reverse direction), thereby causing the porous tube 160 and the activated sludge-containing liquid to It is possible to avoid the situation where the liquid does not move relatively, and it is possible to efficiently disperse bubbles having a small particle diameter in the activated sludge-containing liquid.

  As described above, according to the activated sludge treatment apparatus 100 according to the present embodiment, while suppressing an increase in power consumption of the pump 122, the destruction of flocs is suppressed, and the activated sludge containing liquid has a small particle size efficiently. Air bubbles can be dispersed. Thereby, gas can be efficiently dissolved in the activated sludge-containing liquid, and it becomes possible to improve the decomposition efficiency of pollutants by the activated sludge.

(Second Embodiment)
FIG. 4 is a view for explaining an activated sludge treatment apparatus 200 according to the second embodiment. As shown in FIG. 4, the activated sludge treatment apparatus 200 includes a storage tank 110, connecting pipes 220 a and 220 b, a pump 122, and a microbubble generator 250. Since the storage tank 110 and the pump 122 already described as the constituent elements in the first embodiment have substantially the same functions, a duplicate description is omitted. Here, the connecting pipes 220a and 220b and the microbubble generator 250 having different structures are omitted. Is mainly explained.

  In the present embodiment, the connecting pipes 220a and 220b are pipes that can be expanded and contracted in the flow direction of the activated sludge-containing liquid, and include, for example, resin pipes and flexible pipes.

  FIG. 5 is a diagram for explaining a specific configuration of the microbubble generator 250 according to the second embodiment. As shown in FIG. 5, the microbubble generator 250 includes a porous tube 160, a vibration device 270, and a gas inlet 180. Since the porous tube 160 and the gas introduction unit 180 which have already been described as the constituent elements in the first embodiment have substantially the same functions, the redundant description is omitted. Here, the outer tube 182 and the porous tube having different configurations are used. 160, the connection relationship between the connecting pipes 220a and 220b, and the vibration device 270 will be mainly described.

  In the present embodiment, the outer diameter of the porous tube 160 maintains a dimensional relationship smaller than the inner diameter of the connecting tubes 220a and 220b. In the present embodiment, the outer tube 182 includes a first hole 182a provided at both ends thereof, a second hole 182b that is continuous with the first hole 182a and has a smaller hole diameter than the first hole 182a. Have The first hole 182a maintains a dimensional relationship slightly larger than the outer diameter of the connecting tubes 220a and 220b, and the second hole 182b maintains a dimensional relationship slightly larger than the outer shape of the porous tube 160. Here, the length between the second holes 182b is shorter than the length of the porous tube 160.

  When connecting the microbubble generator 250 to the connecting tubes 220a and 220b, first, the O-ring 274a is inserted into the outer peripheral surface of the porous tube 160 in a state where the porous tube 160 is inserted into both the second holes 182b. . Here, the O-ring 274a maintains a dimensional relationship whose inner diameter is slightly larger than the outer shape of the porous tube 160, and has a dimensional relationship whose outer diameter is substantially equal to or slightly larger than the inner diameters of the connecting tubes 220a and 220b. maintain.

  When the connecting pipes 220a and 220b are inserted into the first hole 182a, the O-ring 274a comes into close contact with the inner peripheral surfaces of the connecting pipes 220a and 220b. Thus, the outer tube 182, the porous tube 160, and the connecting tubes 220a and 220b are kept airtight by the O-ring 274a.

  The vibration device 270 linearly vibrates the porous tube 160 along the flow direction of the activated sludge-containing liquid in the porous tube 160 (indicated by a white arrow in FIG. 5). More specifically, the vibration device 270 includes a fastening member 272, a connecting member 274 connected to the fastening member 272, and a drive unit 276 that drives the connecting member 274.

  The fastening member 272 fastens the outer tube 182 and the connecting member 274. The drive unit 276 causes the connecting member 274 to vibrate in the direction indicated by the white arrow in FIG. Therefore, when the driving unit 276 is driven, the porous tube 160 vibrates linearly via the connecting member 274 and the fastening member 272. In the present embodiment, the drive unit 276 vibrates the porous tube 160 at a frequency of 60 rpm to 2000 rpm, for example.

  Thus, in the microbubble generator 250 of the present embodiment, the vibration device 270 linearly vibrates the porous tube 160 along the flow direction of the activated sludge-containing liquid. In other words, the vibration device 270 vibrates the porous tube 160 in substantially the same direction as the flow direction of the activated sludge-containing liquid. Then, the porous tube 160 (hole 160a) and the activated sludge-containing liquid move relatively in the flow direction of the activated sludge-containing liquid, and the gas introduced through the hole 160a is easily torn off. Thereby, when the flow rates of the activated sludge-containing liquid are equal, it is possible to generate bubbles having a smaller particle diameter as compared with bubbles formed by tearing only with the flow of the activated sludge-containing liquid. In addition, the vibration by the vibration device 270 is absorbed by the connecting pipes 220a and 220b, which are pipes that can expand and contract in the flow direction of the activated sludge-containing liquid.

  Therefore, by vibrating the porous tube 160 while suppressing the flow rate of the activated sludge-containing liquid to such an extent that the floc is not destroyed, the increase in power consumption of the pump 122 is suppressed, and the destruction of the floc is suppressed. Small bubbles (microbubbles) can be dispersed in the activated sludge-containing liquid.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  For example, in the above-described embodiment, the configuration has been described in which the microbubble generation unit includes one of the rotation device 170 and the vibration device 270. However, the microbubble generation unit includes both the rotation device 170 and the vibration device 270. The porous tube 160 can be rotated and oscillated linearly. Thereby, it becomes possible to disperse bubbles having a smaller particle diameter in the activated sludge-containing liquid.

  Moreover, in the said embodiment, although the vibration apparatus 270 is vibrating the porous pipe | tube 160 linearly along the distribution direction of activated sludge containing liquid, it is porous in the direction orthogonal to the distribution direction of activated sludge containing liquid. The tube 160 may be vibrated linearly.

  In the above-described embodiment, the case where the compressed gas is introduced using the compressor 184 has been described as an example. However, if a compressed gas having a desired pressure (for example, 0.3 MPa) can be introduced, a high-pressure cylinder is used. Also good.

  Moreover, in embodiment mentioned above, although compressed air was mentioned as an example and demonstrated as compressed gas, if the processing capability of activated sludge can be improved, compressed oxygen may be sufficient, and it is compressed gas containing oxygen other than air. There may be.

  INDUSTRIAL APPLICABILITY The present invention can be used for an activated sludge treatment apparatus that treats wastewater with activated sludge.

DESCRIPTION OF SYMBOLS 100, 200 ... Activated sludge processing apparatus 110 ... Containment tank 120 ... Connection pipe 160 ... Porous pipe 170 ... Rotating apparatus 172 ... Rotating pipe 176 ... Drive part 180 ... Gas introduction part 270 ... Vibration apparatus

Claims (5)

A porous tube formed of a porous body having a plurality of pores and through which an activated sludge-containing liquid that is a liquid containing activated sludge flows;
A gas introduction part for introducing gas into the activated sludge-containing liquid through the plurality of holes from the outside of the porous tube;
A rotating device that rotates the porous tube about the axis of the porous tube;
An activated sludge treatment apparatus characterized by comprising: A storage tank for storing the activated sludge-containing liquid;
A connecting pipe connected to the storage tank;
With
The rotating device is
One end side is fixed to the porous tube, and the other end side is rotatably connected to the connecting tube;
A drive unit for rotating the rotary tube;
Comprising
2. The activated sludge treatment apparatus according to claim 1, wherein a diameter of the porous tube is larger than a diameter of the rotating tube.   3. The rotating device according to claim 1, wherein the rotating device rotates the porous tube in a rotation direction that is opposite to the predetermined rotation direction after rotating the porous tube in a predetermined rotation direction. 4. Activated sludge treatment equipment.   The activated sludge treatment apparatus according to any one of claims 1 to 3, further comprising a vibration device that vibrates the porous tube linearly. A porous tube formed of a porous body having a plurality of pores and through which an activated sludge-containing liquid that is a liquid containing activated sludge flows;
A gas introduction part for introducing gas into the activated sludge-containing liquid through the plurality of holes from the outside of the porous tube;
A vibration device for linearly vibrating the porous tube;
An activated sludge treatment apparatus characterized by comprising:

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