JP2008253901A - Solid-liquid separator and water treatment apparatus equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized and low-cost solid-liquid separator which has a stable treatment performance and a water treatment apparatus equipped with the solid-liquid separator. <P>SOLUTION: The solid-liquid separator comprises an activated sludge tank, an air supply device for supplying air to the activated sludge tank, a filter unit immersed in the activated sludge tank, an intermittent metering pump A connected to the filter unit, and a blower for supplying air to the air supply device and the intermittent metering pump A. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solid-liquid separation device provided in a water treatment device for treating waste water discharged from a general household or the like, and particularly relates to an activated sludge separation device.

Water treatment apparatuses for treating wastewater discharged from ordinary households are widely used, but downsizing is desired because the installation location is limited. In order to reduce the size of the water treatment apparatus, it is important to stabilize the solid-liquid separation function. For stabilization of the solid-liquid separation function, an apparatus using a filtration membrane was proposed in Patent Document 1. ing.
In Patent Document 1, it is possible to reduce the size by using a membrane filtration device, and it is also possible to reduce the cost by using an air lift pump without using a mechanical pump.

The pump using air as a drive source is generally an air lift pump in a small water treatment apparatus, but is also disclosed in, for example, Patent Document 2.
JP 2000-51664 A Japanese Patent Publication No.57-5593

However, what is described in Patent Document 1 is that filtered water can be obtained with a water head pressure due to a water level difference from the filtered water transfer pipe only when the water level is higher than the lowest water level (LWL). Therefore, at the lowest water level (LWL), there is no difference in water level, and filtered water cannot be obtained.
Even when the water level is at the highest water level (HWL), the water level difference is small compared to the water depth, and sufficient head pressure cannot be obtained. Therefore, in order to obtain the required amount of water, there is a problem that the fluctuation range of the water level must be increased or the effective membrane area must be increased.

Air lift pumps are widely used in water treatment apparatuses, but due to their characteristics, there is a weakness that a lift (height for pumping up water) cannot be made so high with a small amount of air.
In addition, the air supply pipe to the air lift pump and the air supply pipe to other processing equipment are mostly in communication, and it is difficult to achieve an air balance when the fluctuation range of the water level by flow rate adjustment is large. The amount of water transferred when the water level is at the minimum water level (LWL) and the amount of water transferred when the water level is at the maximum water level (HWL) have a large fluctuation range of water volume, and the quantitativeness cannot be maintained. Therefore, there is also a problem that the processing performance is adversely affected.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a small and inexpensive solid / liquid separation device with stable treatment performance and a water treatment device including the solid / liquid separation device. .

The present invention relates to the following.
(1) An activated sludge tank, an air supply device for supplying air to the activated sludge tank, a filtration unit immersed in the activated sludge tank, an intermittent metering pump A connected to the filtration unit, and the air supply The solid-liquid separator provided with the apparatus and the air blower which supplies air to the intermittent metering pump A.
(2) The solid-liquid separation device according to item (1), wherein the activated sludge tank has a fluid carrier for immobilizing microorganisms.
(3) The solid-liquid separation device according to item (1) or (2), wherein the filtration unit uses a submerged membrane or a non-woven fabric as a filtering material.
(4) A water treatment apparatus comprising the solid-liquid separation apparatus according to any one of items (1) to (3) and an anaerobic treatment tank provided in a preceding stage of the solid-liquid separation apparatus.
(5) In the item (4), the activated sludge tank has a flow rate adjusting function and another intermittent metering pump B separately from the intermittent metering pump A connected to the filtration unit. A water treatment device which is communicated by a common air supply pipe for transferring air from the blower and in which the suction pipe water intake of the intermittent metering pump B is installed at a low water level in the activated sludge tank.
(6) The water treatment apparatus according to item (4) or (5), wherein the blower is operated intermittently.

According to the present invention, compared to a conventional solid-liquid separation device such as a sedimentation tank by gravity sedimentation, it is possible to reduce the size and forcibly solid-liquid separation by a filtration unit, so that the separation performance is excellent. A solid-liquid separation device and a water treatment device can be provided.
In addition, since a pump using air as a drive source is used, a solid-liquid separation device and a water treatment device can be provided that are less expensive than a mechanical pump.

The activated sludge tank described in the present invention is a chamber for aerobic treatment of organic substances contained in waste water. Into the activated sludge tank, air is discharged from an air supply device to be described later, the inside of the tank is aerated and agitated, and the inside of the tank is kept aerobic. The dissolved oxygen concentration in the tank is preferably 1 mg / L or more.
Moreover, 3,000-20,000 mg / L is preferable and, as for the sludge density | concentration (MLSS density | concentration) in a tank, 5,000-15,000 mg / L is more preferable.
If it is less than 3,000 mg / L, activated sludge is difficult to flocate, and the biofilm tends to adhere to the filtration material of the filtration unit, causing clogging. Adjust so that
Conversely, if it exceeds 20,000 mg / L, the permeation resistance in the filtration unit may increase and the planned permeated water amount may not be obtained. Therefore, the sludge is extracted and adjusted to 20,000 mg / L or less.

The air supply apparatus described in the present invention is not particularly limited as long as air can be supplied into the activated sludge tank. Specifically, it is possible to use a pipe having holes at regular intervals, a box-shaped rectangular parallelepiped with a large flat area having holes at regular intervals, and the like.
When the sludge concentration in the tank becomes high, clogging is likely to occur, so that the hole diameter is preferably 2.5 mm to 10 mm, and more preferably 3 mm to 5 mm. When the pore diameter is less than 2.5 mm, clogging may occur in several months when the air supply pressure is about 15 kPa and the sludge concentration is 3,000 mg / L or more. When the pore diameter is 10 mm or more, the bubble diameter increases and the bubble surface area with the same amount of air decreases, so that the efficiency of dissolving oxygen in water is extremely deteriorated, which adversely affects the processing performance.
The air supply device is installed at a position where air bubbles hit the filter medium of the filtration unit. This is because air bubbles peel off the biofilm adhering to the filter medium and make it difficult to clog.

The activated sludge tank is preferably provided with a fluid carrier. The fluid carrier is not particularly limited as long as microorganisms can adhere to it. Specifically, those having a granular shape, a cylindrical shape, a cubic shape, a specific gravity of about 1.0, and a size of about 10 mm can be used. By providing a microorganism house that cannot form flocs, biofilm adhesion to the filter medium can be reduced.
Moreover, when the fluid carrier itself hits the filter medium, the biofilm attached to the filter medium is peeled off, and clogging becomes difficult.
The specific gravity of the fluid carrier is preferably 0.94 to 0.98. In this range, the specific gravity becomes close to 1.0 after the microorganisms adhere, and the microorganisms easily flow.
The filling rate of the fluid carrier is preferably 70% or less. If it exceeds 70%, the flow is hindered by the collision between the carriers, and it becomes difficult to flow.

The filtration unit described in the present invention includes a filter medium provided with a filtrate discharge port, a support that supports the filter medium, and a filtrate discharge pipe connected to the filtrate discharge port.
The filter medium is not particularly limited as long as it has a filtration function. Specifically, a microfiltration membrane (MF membrane) having a pore diameter of about 0.1 μm to 10 μm or a non-woven fabric corresponding to a pore diameter of about 10 μm to 1 mm can be used.
The number of filter media is determined by the planned permeate amount.

  The support for supporting the filter medium is not particularly limited as long as the filter medium is fixed in the activated sludge tank. Specifically, for example, if it corresponds to the above flat membrane, a guide is provided in the vertical direction so as to sandwich the end face of the filter medium so as to fix the filtered water permeation portion of the filter medium to be vertical. This is because the filter medium can be moved up and down so that the filter medium can be replaced when the filter medium is damaged or deteriorated.

  When a plurality of filter media are required, the number of guides in the vertical direction corresponding to the number of filter media is prepared so that the filter media are arranged in parallel. The distance between the filter medium and the filter medium is preferably about 2 to 3 times the size of the carrier (maximum length portion of the carrier) in consideration of the flow carrier flowing between the filter media. If it is narrower than this, the fluid carrier does not enter between the filter media, and the biofilm peeling effect of the filter media by the fluid carrier cannot be expected. On the other hand, when the width is larger than this, the unit itself becomes large, which is contrary to the downsizing of the solid-liquid separator.

The filtered water discharge pipe is a water pipe connected to the filtered water discharge port from the filter medium, and is not particularly limited as long as water can be passed. Specifically, a pipe, a tube, or the like can be used.
In the case where there are a plurality of filtrate outlets, it is preferable to connect the filtrate outlets in parallel to form one end of the filtrate outlet pipe. At this time, it is preferable that the diameter area of the end of the filtrate discharge pipe is larger than the total area of the filtrate discharge outlets. By carrying out like this, the head loss by piping resistance is reduced and more filtered water amount can be obtained.

As the intermittent metering pump described in the present invention, an equivalent pump disclosed in Patent Document 2 can be used. The suction pipe (inlet to the pump) of the intermittent metering pump is connected to the filtered water discharge pipe. The position of the high water level (HWL) in the intermittent metering pump is installed at a position lower than the upper end of the filter medium. By installing in this position, water pressure is always applied to the filter medium, and it is possible to always obtain filtered water. Preferably, in the intermittent metering pump, the upper limit of the specified working water pressure of the filter medium and the head pressure due to the water head difference between the high water level (HWL) in the intermittent metering pump and the upper end of the filter medium are equal. The position of the high water level (HWL) is set. By doing so, more filtered water can be obtained.
In some cases, a check valve for preventing backflow may be provided in the suction pipe of the intermittent metering pump. However, in this case, since the water pressure to the filter medium is sufficiently high, it is not always necessary to provide a backflow.

The blower described in the present invention is not particularly limited as long as air can be supplied to the intermittent metering pump and the air supply device. Specifically, a diaphragm pump, a rotary blower, or the like can be used. The blower may be provided for each of the intermittent metering pump and the air supply device, or may be shared.
In addition, when there exists another processing apparatus which requires air, you may combine with the air supply to the processing apparatus.

The water treatment device described in the present invention includes a solid-liquid separation device and an anaerobic treatment tank.
The anaerobic treatment tank is not particularly limited as long as it is provided upstream of the solid-liquid separation device, that is, upstream, and has an anaerobic treatment function. A filter bed tank or the like can be used. An anaerobic treatment tank carries out the anaerobic process of the organic substance contained in sewage, and transfers the supernatant water separated into solid and liquid to a solid-liquid separator. On the other hand, sludge separated into solid and liquid is subjected to anaerobic digestion.

When a flow rate adjusting function is added to the water treatment apparatus described in the present invention, the following can be performed.
The flow rate adjustment function is a function for alleviating a large inflow peak, and includes a storage function and a water supply function.
The storage function is a function of temporarily storing the inflowing sewage, and can have a function by changing the water level in the upper part of the activated sludge tank. In this case, the setting of the low water level (LWL) is determined by the intake pipe intake position of another intermittent metering pump with which the air supply pipe communicates.
The water supply function can also be used as an intermittent metering pump connected to the filtration unit. The water supply destination is a subsequent processing device of the solid-liquid separator.
The water supply destination of other intermittent metering pumps is preferably an anaerobic treatment tank. By doing in this way, since the denitrification effect can be expected and organic matter is consumed, the treatment performance can be stabilized.

  By using the blower with a timer function, the activated sludge tank can be intermittently operated. By doing in this way, since the denitrification effect can be expected and organic matter is consumed, the treatment performance can be stabilized. When the blower is also used, aeration stops while the blower is stopped, and bubbles do not hit the surface of the filter medium. However, the intermittent metering pump also stops, so there is no risk of the filter medium being clogged.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic elevation view of a water treatment apparatus according to one embodiment of the present invention.
The water treatment apparatus 1 has an anaerobic filter bed tank 2, a solid-liquid separation apparatus 3, and a disinfection tank 4.
The anaerobic filter bed tank 2 has a filter bed 21 and the filter medium is a mesh-like cylindrical filter medium.
The solid-liquid separation device 3 includes an activated sludge tank 31, an air supply device 32, a filtration unit 33, an intermittent metering pump 34, and a blower 35.

Hereinafter, it demonstrates along the flow of waste_water | drain.
Drainage flows into the anaerobic filter bed tank 2 through the inlet 11. The solid matter in the drained wastewater is captured by the filter bed 21 and anaerobically decomposed, and then settles at the bottom of the anaerobic filter bed tank 2. The settled solids are pulled out together with the sludge during cleaning. The transfer channel 22 also serves as a cleaning hole. The waste water from which the solid matter has been separated is transferred to the solid-liquid separator 3 through the transfer port 23.
The water that has flowed into the activated sludge tank 31 of the solid-liquid separator 3 is subjected to an aerobic treatment in a tank that is kept in an aerobic state by bubbles released from the air supply device 32. The aerobic treated water is filtered by the filtration unit 33, sterilized in the disinfection tank 4 through the intermittent metering pump 34, and discharged from the outlet 12.

The filtration unit 33 includes a filter medium 331 provided with a filtrate discharge port 332, a support 333 that supports the filter medium 331, and a filtrate discharge pipe 334 connected to the filtrate discharge port 332.
As the filter medium 331, a spunbond nonwoven fabric made of polypropylene (manufactured by Nippon Nonwoven Fabric Co., Ltd., trade name: SPRITOP, product number: SP-1070EHY) was used. Since the nonwoven fabric made of polypropylene is hydrophobic and is not easily adapted to water, a hydrophilic material in which a hydrophilic agent is kneaded into the fabric is preferable. A hydrophilic material can exhibit performance from the beginning.
If it is operated for a long time, a biofilm or the like will eventually adhere to the surface of the filter medium and close up. Therefore, in order to peel off the attached biofilm, the air supply device 32 is disposed immediately below the filter medium 331 so that the bubbles hit the filter medium surface. Further, a cylindrical fluid carrier (not shown) having a diameter of 12 mm is charged at a filling rate of 30% so that the fluid carrier also hits the filter medium surface.

The water in the activated sludge tank 31 passes through the filter medium 331 and is collected at the filtrate outlet 332 at the top. Then, it is sent to the intermittent metering pump 34 through the filtered water discharge pipe 334.
The intermittent metering pump 34 is installed at a position about 1/2 the height of the filter medium 331 so that a sufficient filtered head pressure can be obtained. The filtered water discharge pipe 334 is also submerged.
The water level in the activated sludge tank 31 decreases as the treated water is sent from the intermittent metering pump 34 to the disinfecting tank 4. Therefore, the water level detection means 36 is provided in the activated sludge tank 31 to detect the low water level (LWL) so that the filter medium 331 is not exposed to the air, and the air supply stop means 37 (in this embodiment). The air supply to the intermittent metering pump 34 is stopped by using a solenoid valve. The water level detection means 36 is not particularly limited, and specifically, a water level sensor or the like is used. The air supply stop means 37 is not particularly limited, and specifically, an electromagnetic valve or the like is used.

In the present embodiment, a sedimentation section 311 is provided in the activated sludge tank 31. In the sedimentation part 311, the upper part is divided into a supernatant water area and the lower part is divided into an activated sludge area by gravity sedimentation of the activated sludge. If the intermittent metering pump 34 stops due to a failure of the blower 35 or the like, the supernatant water at the top of the sedimentation unit 311 is transferred to the disinfection tank 4 via the overflow port 312. A porous member (not shown) is provided at the communicating part at the bottom of the precipitation part 311 so that the fluid carrier does not flow out. In addition, extraction of the sludge of the activated sludge tank 31 is performed from this sedimentation part 311 so that a fluid carrier may not be extracted out of the system.
Since scum is generated in the sedimentation section 311 as the sludge concentration in the activated sludge tank 31 increases, a scum baffle 313 is provided at the overflow port 312 to prevent the scum from flowing out to the disinfection tank 4. The sedimentation section 311 also has a function of scumming and storing sludge so that the sludge concentration in the activated sludge tank 31 does not become too high.

  The blower 35 is equipped with a timer, and an operation / stop cycle of the blower 35 is possible. During the operation of the blower 35, the activated sludge tank 31 is in an aerobic state, and during the stop, the activated sludge tank 31 is in an anaerobic state, and denitrification can be expected. Since the interval between operation and stop varies depending on conditions such as inflow load and activated sludge concentration, a variable timer is used.

Other embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic elevation view of a water treatment apparatus according to another embodiment of the present invention, and FIGS. 3 to 8 are schematic views showing the operation of the intermittent metering pump.
In the present embodiment, another intermittent metering pump 34 b is installed in the sedimentation section 311. The intermittent metering pump 34 and the intermittent metering pump 34 b communicate with each other through an air supply pipe 351.
When the water level of the activated sludge tank 31 is above the low water level (LWL), water is supplied into both intermittent metering pumps, and water supply / water supply is performed. At this time, the water supply amount ratio of the intermittent metering pumps 34, 34b is the water area ratio in each intermittent metering pump. For example, when it is desired to set the water supply amount of the intermittent metering pump 34 to 2Q and the water supply amount of the intermittent metering pump 34b to 3Q, the water area (horizontal sectional area) in the intermittent metering pump 34 is 2S, and the water area in the intermittent metering pump 34b. Is 3S.

FIG. 3 is a diagram illustrating a water supply process. In this process, since air escapes from the discharge pipe 342 of the intermittent metering pump 34, a water head pressure is generated in both the intermittent metering pumps 34 and 34 b, and the intermittent metering pump 34 is intermittently metered from the suction pipe 341 connected to the filtered water discharge pipe. The pump 34b is supplied with water from the intake port of the suction pipe 341b.
FIG. 4 is a diagram at the moment of switching from the water supply process to the water supply process. When the water surface reaches the top of the U-shaped tube 344 in the intermittent metering pump 34 (HWL), water flows into the bottom of the U-shaped tube 344 and a trap is formed. Then, there is no place for air to escape, and air pressure is applied to both water surfaces in the intermittent metering pumps 34 and 34b. At this time, the check valve 343 is closed to prevent backflow.
FIG. 5 is a diagram illustrating a water supply process. Water is discharged from the discharge pipes 342 and 342b by the air pressure applied to both water surfaces in the intermittent metering pumps 34 and 34b. Then, the water level in the intermittent metering pumps 34, 34b gradually decreases.
FIG. 6 is a diagram at the moment of switching from the water supply process to the water supply process. When the water surface reaches the bottom of the U-shaped tube 344 in the intermittent metering pump 34 (LWL), the trap is cut and air escapes from the discharge tube 342, and is applied to both water surfaces in the intermittent metering pumps 34 and 34b. The air pressure is lost to the water head pressure, and the water supply process shown in FIG. 3 is performed again. The residual water in the discharge pipes 342 and 342b is returned into the intermittent metering pumps 34 and 34b.

However, when the water level of the activated sludge tank 31 is low (LWL), the intermittent metering pump 34 is supplied from the suction pipe 341, but the intermittent metering pump 34b is supplied with water from the intake port of the suction pipe 341b. Is not supplied. When the water surface reaches the top of the U-shaped tube 344 in the intermittent metering pump 34 (HWL), water is discharged from the discharge tubes 342 and 342b, respectively (see FIG. 7).
Immediately thereafter, the intermittent metering pump 34b runs out of water to be sent and becomes empty (see FIG. 8). At this time, since the air supplied from the air supply pipe 351 escapes from the discharge pipe 342b as it is, no air pressure is applied to the water surface in the intermittent metering pump 34 and water is not sent from the discharge pipe 342. This state is continued as long as the water level of the activated sludge tank 31 is a low water level (LWL).
That is, the suction pipe 341b is a water level detection unit, and the intermittent metering pump 34b is an air supply stop unit.

  The scum floats on the sedimentation unit 311 but is returned to the anaerobic filter bed tank 2 by the intermittent metering pump 34b and reprocessed to stabilize the processing performance. Since the scum is gradually returned, it does not thicken, and even when an abnormal peak is applied, there is no possibility that the scum will flow over the scum baffle 313 to the disinfection tank 4 from the overflow port 312.

1 is a schematic elevation view of a water treatment apparatus according to one embodiment of the present invention. It is a schematic elevation view of the water treatment apparatus which is another Example which concerns on this invention. The water supply process figure of an intermittent metering pump in case a water level is above a low water level (LWL). The figure of the moment which switches from a water supply process to a water supply process in case a water level is above a low water level (LWL). The water supply process figure of an intermittent metering pump in case a water level is above a low water level (LWL). The figure of the moment which switches from a water supply process to a water supply process in case a water level is above a low water level (LWL). The figure of the moment when a water level switches from a water supply process at the time of a low water level (LWL) to a water supply process. The figure when the water supply process at the time of a water level being a low water level (LWL) is completed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Water treatment apparatus, 2 ... Anaerobic filter bed tank, 3 ... Solid-liquid separation apparatus, 4 ... Disinfection tank,
11 ... Inlet, 12 ... Outlet,
21 ... Filter bed, 22 ... Transfer channel, 23 ... Transfer port,
31 ... Activated sludge tank, 32 ... Air supply device, 33 ... Filtration unit, 34 ... Intermittent metering pump,
35 ... Air blower, 36 ... Water level detection means, 37 ... Air supply stop means 311 ... Precipitation part, 312 ... Overflow port, 313 ... Scum baffle 331 ... Filter material, 332 ... Filtrated water discharge port, 333 ... Support, 334 ... Filtration Water discharge pipe,
34b ... intermittent metering pump,
341 ... Suction pipe, 341b ... Suction pipe, 342 ... Discharge pipe, 342b ... Discharge pipe,
343 ... Check valve, 344 ... U-shaped pipe, 351 ... Air supply pipe.

Claims (6)

  An activated sludge tank, an air supply device for supplying air to the activated sludge tank, a filtration unit immersed in the activated sludge tank, an intermittent metering pump A connected to the filtration unit, the air supply device and the intermittent A solid-liquid separator comprising a blower for supplying air to the metering pump A.   The solid-liquid separator according to claim 1, wherein the activated sludge tank has a fluid carrier for immobilizing microorganisms.   3. The solid-liquid separator according to claim 1, wherein the filtration unit uses a submerged membrane or a nonwoven fabric as a filtering material.   A water treatment apparatus comprising: the solid-liquid separation apparatus according to any one of claims 1 to 3; and an anaerobic treatment tank provided at a front stage of the solid-liquid separation apparatus.   In claim 4, the activated sludge tank has a flow rate adjustment function and another intermittent metering pump B separately from the intermittent metering pump A connected to the filtration unit, and the intermittent metering pumps A and B are supplied from the blower. A water treatment apparatus which is communicated by a common air supply pipe for transferring air, and in which an intake pipe intake of the intermittent metering pump B is installed at a low water level in the activated sludge tank.   The water treatment apparatus according to claim 4 or 5, wherein the blower is operated intermittently.

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