JP2008006360A - Filtration concentration apparatus and filtration concentration method - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a sludge filtration and concentration device and a filtration and concentration method thereof in a water purification plant, a sewage treatment plant, and the like.

In general, sludge discharged from a water purification plant or sewage treatment plant is concentrated in a gravity sedimentation tank and then mechanically dehydrated to a concentrated sludge with a water content of 80% or less. The concentrated sludge is incinerated and disposed of in landfills. .
In the conventional sludge concentration in the gravity settling tank, the residence time is long and the moisture content varies greatly depending on the properties of the sludge. Therefore, it is difficult to stably operate the mechanical dehydration. Therefore, a filtration and concentration device was developed as an alternative to the gravity sedimentation tank.
Patent Document 1 is cited as a document describing a conventional filtration and concentration device, but there is an insufficient description in the operation. Then, it demonstrates using FIG. 14, supplementing operation | movement of the conventional filtration concentration apparatus.

  First, the apparatus configuration will be described. In this filtration concentration apparatus, the inside of the can 22 is partitioned into an upper chamber 24 and a lower chamber 25 by a partition plate 23, and a plurality of filter bodies 26 are suspended from the partition plate 23 into the lower chamber 25. An air introduction pipe 36 is provided in the upper chamber 24 canopy. A supply / exhaust pipe 37 is provided in the upper part of the lower chamber 25, and a liquid to be processed introduction pipe 27 is provided in the bottom part. The filtrate discharge pipe 28 is provided with a filtrate valve 29, and further connected with a storage tank 32 and a vacuum line 33 provided with an air pump 31 via a vacuum valve 30 upstream of the filtrate valve 29. Are connected to lines having a drain valve 34 and an intake valve 35, respectively. The length of the filter body 26 is, for example, about 1.5 m.

  Next, the operation will be described. First, pressure filtration is performed first. The supply / exhaust pipe 37 is closed, and the liquid to be processed is introduced into the lower chamber 25 through the liquid inlet pipe 27 to be processed and filtered through the filter body 26. The filtrate moves into the upper chamber 24 and is discharged to a predetermined destination through the filtrate discharge pipe 28 and the filtrate valve 29. At this time, the air introduction pipe 36 is closed. The suspension in the liquid to be treated is captured and attached as filter cake (corresponding to the concentrated sludge of the present application) on the surface of the filter body 26.

Next, the pressure reduction of the upper chamber 24 is started by the air pump 31 while the pressure filtration is continued. That is, the drain valve 34 and the intake valve 35 are closed, the vacuum valve 30 is opened, and the air pump 31 is operated.
Next, the filtrate valve 29 is closed and the pressure filtration is stopped. Then, the air supply / exhaust pipe 37 is opened to the atmosphere, and unconcentrated sludge in the lower chamber 25 is discharged from the liquid inlet pipe 27 to be treated. At this time, the pressure reduction by the air pump 31 is continuing. In order to maintain the reduced pressure, the volume of the storage tank 32 must be equal to or greater than the total volume of the volume of the upper chamber 24 and the filter body 26 and the amount of water of the attached concentrated sludge. Otherwise, the filtrate flows into the air pump 31, which is inconvenient. If the pressure reduction is continued, the moisture content of the concentrated sludge is further reduced, and after a while, cracks are generated in the concentrated sludge and air also flows into the upper chamber 24. Then, the filtrate on the secondary side of the upper chamber 24 and the filter body 26 is sucked and removed.

Next, the air introduction pipe 36 is opened to introduce compressed air into the upper chamber 24. Then, the filter body 26 swells from the secondary side, and the concentrated sludge adhering to the primary side of the filter body 26 is peeled off.
In addition, according to the above-mentioned apparatus configuration and operation, a drainage device using power such as a pump is not described in the piping of the filtrate discharge pipe 28 and the drainage valve 34.
JP 2006-21097 A

The volume of the storage tank 32 must be equal to or greater than the total volume of the volume of the upper chamber 24 and the filter body 26 and the amount of water of the attached concentrated sludge, so that the storage tank 32 is enlarged when the apparatus scale is increased. There was a point.
Therefore, the present invention provides a filtration and concentration apparatus and a filtration and concentration method that can reduce the capacity of a storage tank and efficiently obtain concentrated sludge having a high concentration.

The problem of the present invention is solved by discharging the filtrate in the storage tank during the operation of the air pump.
That is, the features of the present invention are a sludge tank, a sludge supply means for supplying sludge to the sludge tank, a filtration unit installed in the sludge tank to filter the sludge, and the sludge tank outside the sludge tank. A filtrate discharge pipe drawn into the filter, a non-concentrated sludge discharging means, a peeling means for peeling the concentrated sludge adhering to the filtration part, a concentrated sludge discharging means for discharging the peeled concentrated sludge from the sludge tank, and the filtrate discharging. A storage tank installed in the middle of the pipe, an air pump capable of discharging gas to the storage tank and sucking the gas in the storage tank, a gas flow pipe connecting the storage tank and the air pump, and the sludge supply In a filtration and concentration device comprising a means and a sludge supply pipe communicating with the sludge tank, a pressure gauge that measures the pressure of the storage tank, and a water level measurement means that measures the water level inside the storage tank, A liquid pump communicating with the filtrate discharge pipe downstream from the storage tank, the sludge supply means, the unconcentrated sludge discharge means, the stripping means, the concentrated sludge discharge means, the filtrate discharge pipe, and the gas flow The object is to include a valve provided in each of the fluid flow paths of the pipe and a control device.

According to a second aspect of the present invention, in the filtration and concentration apparatus according to the first aspect of the present invention, an atmosphere release valve is provided for communicating or blocking the interior of the storage tank and the atmosphere.
The invention of claim 3 includes a sludge supply step, an air pump filtration step, and an unconcentrated sludge discharge step, wherein the sludge supply step, the air pump filtration step, and the unconcentrated sludge discharge step are In the filtration and concentration method in which the concentrated sludge separation step is executed after all the steps are completed, the liquid pump filtration step for controlling the liquid water level in the storage tank within a predetermined range, and the air pump filtration step for sucking the gas in the storage tank Is to execute simultaneously.
According to a fourth aspect of the present invention, in the filtration and concentration method according to the third aspect, the air pump filtration step and the unconcentrated sludge discharge step are performed simultaneously.
And the characteristic of invention of Claim 5 is the filtration flow path drainage process which discharges | emits the liquid of the said storage tank and the said filtrate discharge pipe before the said concentration sludge peeling process in the filtration concentration method of Claim 3 or 4 Is to execute.
According to a sixth aspect of the present invention, in the filtration and concentration method according to any one of the third to fifth aspects, the measured value of the pressure gauge is compared with a predetermined pressure value in the air pump filtration step. The operation of the air pump is continued when the measured value of the pressure gauge is larger than the predetermined pressure value, and the operation of the air pump is stopped when the measured value of the pressure gauge is less than the predetermined pressure value.
A seventh aspect of the present invention is the filtration and concentration method according to any one of the third to sixth aspects, wherein the air pump in the air pump filtration step is after a predetermined time has elapsed since the operation of the air pump. , To stop.
The invention according to claim 8 is characterized in that, in the filtration and concentration method according to any one of claims 3 to 7, when the liquid pump and the air pump operate simultaneously, the gas pressure in the storage tank is Is within the allowable operating pressure range of the liquid pump.

According to invention of Claim 1, the volume of a storage tank can be made small. Further, since it is not necessary to make the sludge tank an airtight container, the structure is easy to manufacture even when the scale is increased.
According to the second aspect of the present invention, the air release valve that allows the inside of the storage tank to communicate with the atmosphere is provided. During the filtration, the air release valve is closed, and before the concentrated sludge is peeled off by supplying the gas to the filtration unit with an air pump. In order to reduce the concentration of concentrated sludge, the filtrate inside the storage tank and the storage tank are removed by removing the filtrate from the filtrate discharge pipe and the storage tank. Can be prevented.
According to the invention of claim 3, a sludge supply step, an air pump filtration step, and an unconcentrated sludge discharge step are provided, and the sludge supply step, the air pump filtration step, and the unconcentrated sludge discharge step are all completed. In the filtration and concentration method for performing the concentrated sludge stripping process after the process, the liquid pump filtration process for controlling the liquid water level in the storage tank within a predetermined range, and the air pump filtration process for sucking the gas in the storage tank By executing simultaneously, the volume of the storage tank can be reduced.
According to the invention of claim 4, by simultaneously performing the air pump filtration step and the non-concentrated sludge discharge step, the concentrated sludge on the filter plate surface is dropped together with the non-concentrated sludge during the non-concentrated sludge discharge step. Can be prevented. That is, the semi-solid concentrated sludge produced during the siphon filtration step is further reduced in water content by air pump filtration and is maintained in a state of adhering to the filter plate surface.
According to the invention of claim 5, before the concentrated sludge stripping step, a filtrate channel draining step for draining the liquid in the storage tank and the filtrate discharge pipe is performed, so that the storage tank and the filtrate discharge pipe are It is possible to prevent the liquid from flowing back to the filtration part and reducing the concentration of the concentrated sludge.
According to the invention of claim 6, in the air pump filtration step, the measured value of the pressure gauge is compared with a predetermined pressure value, and the operation of the air pump is performed when the measured value of the pressure gauge is larger than the predetermined pressure value. And by stopping the operation of the air pump when the measured value of the pressure gauge is equal to or lower than the predetermined pressure value, excessive pressure reduction of the air pump can be prevented, and concentration filtration can be executed with energy saving.
According to the seventh aspect of the present invention, the air pump in the air pump filtration step is stopped after a predetermined time from the operation of the air pump, so that the concentration filtration can be reliably performed even when the pressure gauge is broken. Can progress and improve fault tolerance.
According to the eighth aspect of the present invention, when the liquid pump and the air pump are operated simultaneously, the gas pressure in the storage tank is set within the allowable operating pressure range of the liquid pump, so It is possible to prevent the load from being applied and to reduce the risk of failure of the liquid pump.

First, the structure of the filtration concentration apparatus of this invention is demonstrated. FIG. 1 is a configuration diagram of a filtration and concentration apparatus according to an embodiment of the present invention.
1 includes a sludge tank 1 having a tapered bottom, a sludge supply / discharge pump 2 which is a sludge supply means and an unconcentrated sludge discharge means to the sludge tank 1, and a sludge tank 1. When supplying the raw sludge, the sludge supply / discharge pump 2 is operated to enter the sludge to a predetermined water level, and a water level meter 18 for detecting the sludge water level and a filtration unit installed in the sludge tank 1 for filtering the sludge. 3, a filtrate discharge pipe 4 drawn from the filtration unit to the outside of the sludge tank 1, valves 10 and 38, and a concentrated sludge pump which is a concentrated sludge discharge means for discharging concentrated sludge filtered and concentrated from the sludge tank 1 39, the concentrated sludge discharge pipe 42, the valve 9, the water level gauge 20, the storage tank 5 installed between the valve 10 and the valve 38 in the middle of the filtrate discharge pipe 4, and the gas is discharged and stored in the storage tank 5. The gas in the tank 5 can be sucked and adhered to the filtration unit 3 The air pump 7 which is a part of the stripping means for stripping the reduced sludge, the valve 13, the gas flow pipe 40 which communicates the storage tank 5 and the air pump 7, the sludge supply / discharge pump 2 and the sludge tank 1 are communicated. In the filtration and concentration apparatus including the sludge supply pipe 41 and the valve 8, the pressure gauge 17 that measures the pressure of the storage tank 5, the water level gauge 19 that measures the water level inside the storage tank 5, and the downstream of the storage tank 5 A liquid pump 16 and a valve 11 communicated with the filtrate discharge pipe 4, a tap water supply pipe 6 and a valve 12 for supplying water to the storage tank 5, an air release pipe 43 for discharging the air accumulated in the storage tank 5, and The valve 14 and a control device (not shown) are provided.

  The outlet height of the filtrate discharge pipe 4 is set to be lower than the lower end of the filtration unit 3. Moreover, the filtration part 3 consists of the bag-shaped filtration membrane 3a which isolates a filtrate and sludge, and the filter frame 3b which supports the filtration membrane 3a. An air distribution pipe 15 for sucking the filtrate and peeling the concentrated sludge is provided on the inner upper part of the filtration membrane 3a. The air distribution pipe 15 is a round or square pipe made of metal, vinyl chloride, or the like installed in the horizontal direction, and a plurality of small holes are provided vertically downward in the lower part of the pipe. The small holes are provided for sucking the filtrate in the filtration unit 3 and for supplying pressurized air for separating the concentrated sludge from the filtration membrane 3a. The end of the air distribution pipe 15 that is not connected to the filtrate discharge pipe 4 is sealed.

  An input / output diagram of the control device of the filtration concentration apparatus according to the present invention is shown in FIG. At least the water level signals of the water level gauges 18, 19, and 20, the pressure signal of the pressure gauge 17, the siphon filtration setting time, the liquid pump filtration setting time, and the air pump filtration setting time are input to the control device. The control device outputs signals for controlling the valves 8 to 14 and 38, the sludge supply / discharge pump 2, the air pump 7, the liquid pump 16, and the concentrated sludge pump 39.

Next, the operation method of the filtration concentration apparatus will be described.
FIG. 3 shows an operation flowchart of the filtration concentration method according to the present invention. When the control device receives the filtration and concentration start signal, the control device executes the sludge supply step A and then the siphon formation step.
Next, the siphon filtration process and the sludge supply process B are performed in parallel. When gas accumulates in the storage tank 5 during the siphon filtration process and the pressure rises, the siphon filtration process is interrupted and the siphon formation process is executed to remove the gas inside the storage tank 5 and then the siphon filtration process. Return.

After the siphon filtration step is executed for a predetermined time, the air pump filtration step, the liquid pump filtration step, and the unconcentrated sludge discharge step are executed in parallel. After the air pump filtration process is completed, the filtrate flow path draining process, the concentrated sludge peeling process, and the concentrated sludge discharging process are executed in this order, and the series of filtration and concentration operations is completed.
Below, each process is demonstrated in detail.

  A flow chart of the sludge supply steps A and B is shown in FIG. At the start, valves 8-14, 38 are all closed. In the sludge supply steps A and B, first, the valve 8 is opened and the sludge supply / discharge pump 2 is operated to supply the sludge to a predetermined water level where the filter plate 3 installed in the sludge tank 1 is submerged. This predetermined water level is determined by whether or not the water level H of the water level gauge 18 has been reached. In the sludge supply process B, the sludge supply / discharge pump 2 and the valve 8 are operated and stopped as described above in order to maintain the sludge water level at a predetermined level during the siphon filtration process.

Next, flow charts of the siphon forming process are shown in FIGS. After the valves 12 and 14 are opened and water is supplied until the storage tank 5 reaches a predetermined water level, the valves 12 and 14 are closed. This predetermined water level is determined by whether or not the water level H of the water level gauge 19 has been reached.
When the siphon forming process is performed using the air pump 7, the valve 13 is opened, the gas is sucked by the air pump 7, the inside of the storage tank 5 is decompressed, and suction is performed until the water level of the storage tank 5 reaches a predetermined water level. After that, the valve 13 is closed. In this case, the tap water supply pipe 6, the air release pipe 43, and the valves 12 and 14 need not be installed.

  Next, a flow chart of the siphon filtration process is shown in FIG. Valves 10 and 38 are opened to begin filtration. The supply of sludge and the siphon filtration process in the sludge supply process B are continued until the thickness of the sludge deposited on the filtration membrane 3a is preferably 10 to 13 mm. The time for which the filtration is continued may be carried out by examining the relationship between the sludge deposition thickness and the filtration time in advance, and thereafter using the filtration time when the sludge deposition thickness is 10 to 13 mm as an index. Specifically, in the case of filtration concentration of purified water sludge, for example, filtration is performed for 90 minutes. The pressure generated here is about -30 kPa.

Next, a flow chart of the unconcentrated sludge discharging step is shown in FIG. The valve 8 is opened and the sludge supply / discharge pump 2 is reversely operated to discharge the unconcentrated sludge that has not adhered to the surface of the filtration membrane 3a from the sludge tank 1. The control device determines whether unconcentrated sludge is discharged from the sludge tank 1 using the water level L signal of the water level gauge 18, stops the sludge supply / discharge pump 2, and closes the valve 8.
Next, FIG. 9 shows a flowchart of the liquid pump filtration process. The valves 10 and 11 are opened and the liquid pump 16 is operated, and at the same time, measurement of the liquid pump operation elapsed time is started. The pressure generated in the storage tank at the beginning of liquid pump filtration is about −80 to −90 kPa. Then, it is compared whether or not the liquid pump operation elapsed time is longer than the liquid pump filtration set time. When the liquid pump operation elapsed time is smaller than the liquid pump filtration set time, the water level of the water level gauge 19 and the water level L of the storage tank are further compared. When the water level of the water level gauge 19 is higher than the storage tank water level L, the process returns to the process of comparing whether or not the liquid pump operation elapsed time is equal to or longer than the liquid pump filtration set time, and this process loop is executed. Since the unconcentrated sludge discharge process operates simultaneously with the liquid pump filtration process, the concentrated sludge adhering to the surface of the filtration membrane 3a above the water level that is falling by the unconcentrated sludge discharge process is subjected to liquid pump filtration while being in contact with the outside air. Is called. Further, when the liquid pump operation elapsed time is larger than the liquid pump filtration set time, and when the liquid pump operation elapsed time is smaller than the liquid pump filtration set time and the water level of the water level gauge 19 is lower than the storage tank water level L, the liquid The pump 16 is stopped, the valve 11 is closed, and the measurement of the liquid pump operation elapsed time is finished.

Next, the flowchart of an air pump filtration process is shown in FIG. The valves 10 and 13 are opened, and the air pump 7 is operated so as to reduce the pressure in the storage tank 5, and at the same time, the measurement of the elapsed time of the air pump operation is started. When the liquid pump 16 and the air pump 7 operate simultaneously, the gas pressure in the storage tank 5 is set within the allowable operating pressure range of the liquid pump 16.
When the water level of the storage tank 5 becomes equal to or higher than the water level H, the valves 10 and 13 are closed. And a filtrate flow path drainage process is performed. When the air pump operation elapsed time is equal to or longer than the air pump filtration set time, the valves 10 and 13 are closed, the air pump is stopped, and the air pump filtration process is ended.

  Next, a flow chart of the filtrate flow path draining process is shown in FIG. First, the valve 14 is opened. And in order to remove the filtrate of the storage tank 5 and the filtrate discharge pipe 4, the valve 38 is opened, and after the filtrate of the storage tank 5 is drained, the valves 14 and 38 are closed. Instead of the above-described method of “opening the valve 38 and closing the valves 14 and 38 after the filtrate in the storage tank 5 is drained”, the valve 11 is opened and the liquid pump 16 is operated until the water level in the storage tank 5 reaches the water level L. Then, the valves 11 and 14 may be closed to stop the liquid pump 16.

  Next, a flow chart of the concentrated sludge peeling step is shown in FIG. The valves 10 and 13 are opened, and air is introduced into the secondary side of the filtration membrane 3a with the air pump 7 to pressurize it, and the measurement of the elapsed peeling time is started. Then, the bag-like filtration membrane 3a swells, and the concentrated sludge adhering to the primary surface of the filtration membrane 3a is peeled off from the filtration membrane 3a and falls. The concentrated sludge that has fallen is deposited on the bottom of the sludge tank 1. The peeling elapsed time and the peeling set time are compared. If the peeling elapsed time is equal to or longer than the peeling set time, the operation of the air pump is stopped and the valves 10 and 13 are closed.

  Next, FIG. 13 shows a flowchart of the concentrated sludge discharging step. The valve 9 is opened, the concentrated sludge pump is operated, and the concentrated sludge is discharged from the sludge tank 1. When the water level of the concentrated sludge is compared with the water level of the water level meter 20 and the water level of the concentrated sludge is below the water level of the water level meter 20, the concentrated sludge pump is stopped and the valve 9 is closed. In the concentrated sludge discharging step, the operation time of the concentrated sludge pump may be set in advance with a timer instead of using the water level gauge 20, and the concentrated sludge pump may be stopped when the set time is reached.

In this embodiment, the water level is detected using each water level meter, but the water level of each tank may be measured by calculating from the discharge or suction volume of each pump and each tank size.
As a result, in the siphon filtration step, the concentration which was about 1.5 times the initial concentration of the sludge put into the sludge tank 1 was further increased to about 1.3 after the air pump filtration step and the liquid pump filtration step. Double concentration of concentrated sludge was obtained.

Configuration diagram of filtration concentration apparatus according to the present invention Input / output diagram of the control device of the filtration concentration device according to the present invention Operation flow diagram of filtration concentration method according to the present invention Sludge supply process A and B flow chart Siphon formation process flow diagram (when using externally supplied water) Siphon formation process flow diagram (when using an air pump) Siphon filtration process flow chart Flow chart of unconcentrated sludge discharge process Flow diagram of liquid pump filtration process Flow chart of filtrate flow path drainage process Flow diagram of air pump filtration process Flow chart of concentrated sludge stripping process Flow chart of concentrated sludge discharge process Configuration diagram of conventional filtration and concentration equipment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sludge tank 2 Sludge supply and discharge pump 3 Filtration part 3a Filtration membrane 3b Filter frame 4 Filtrate discharge pipe 5 Storage tank 6 Tap water supply pipe 7 Air pump 8-14 Valve 15 Air distribution pipe 16 Liquid pump 17 Pressure gauge 18-20 Water level gauge 21 Filtration concentrator 22 Can body 23 Partition plate 24 Upper chamber 25 Lower chamber 26 Filter body 27 Processed liquid introduction pipe 28 Filtrate discharge pipe 29 Filtrate valve 30 Vacuum valve 31 Vacuum pump 32 Storage tank 33 Vacuum line 34 Drain valve 35 Intake valve 36 Air introduction pipe 37 Supply / exhaust pipe 38 Valve 39 Concentrated sludge pump 40 Gas flow pipe 41 Sludge supply pipe 42 Concentrated sludge discharge pipe 43 Atmospheric release pipe

Claims (8)

A sludge tank, a sludge supply means for supplying sludge to the sludge tank, a filtration unit installed in the sludge tank for filtering the sludge, a filtrate discharge pipe drawn out of the sludge tank from the filtration unit, Unconcentrated sludge discharging means, peeling means for peeling the concentrated sludge adhering to the filtration unit, concentrated sludge discharging means for discharging the peeled concentrated sludge from the sludge tank, and a storage tank installed in the middle of the filtrate discharge pipe An air pump capable of discharging gas to the storage tank and sucking the gas in the storage tank, a gas flow pipe communicating the storage tank and the air pump, and connecting the sludge supply means and the sludge tank. In a filtration and concentration device equipped with a sludge supply pipe,
A pressure gauge for measuring the pressure of the storage tank, a water level measuring means for measuring the water level inside the storage tank, a liquid pump communicating with the filtrate discharge pipe downstream from the storage tank, the sludge supply means, Filtration concentration characterized by comprising a control device and a valve provided in each of the fluid flow paths of the unconcentrated sludge discharging means, the peeling means, the concentrated sludge discharging means, the filtrate discharge pipe, and the gas flow pipe. apparatus.   The filtration concentration apparatus according to claim 1, further comprising an atmosphere release valve that communicates or blocks the inside of the storage tank and the atmosphere. A sludge supply step, an air pump filtration step, and an unconcentrated sludge discharge step are provided, and the concentrated sludge stripping step is executed after all of the sludge supply step, the air pump filtration step, and the unconcentrated sludge discharge step are completed. In the filtration and concentration method,
A filtration and concentration method, wherein the liquid pump filtration step for controlling the liquid water level in the storage tank within a predetermined range and the air pump filtration step for sucking the gas in the storage tank are performed simultaneously.   The filtration and concentration method according to claim 3, wherein the air pump filtration step and the unconcentrated sludge discharge step are performed simultaneously.   5. The filtration and concentration method according to claim 3, wherein a filtrate flow path draining process for discharging the liquid in the storage tank and the filtrate discharge pipe is performed before the concentrated sludge peeling process.   In the air pump filtration step, the measured value of the pressure gauge is compared with a predetermined pressure value, and when the measured value of the pressure gauge is larger than the predetermined pressure value, the operation of the air pump is continued, and the measurement of the pressure gauge is performed. The filtration concentration method according to any one of claims 3 to 5, wherein the operation of the air pump is stopped when a value is equal to or less than the predetermined pressure value.   The filtration and concentration method according to any one of claims 3 to 6, wherein the air pump in the air pump filtration step is stopped after a predetermined time has elapsed since the operation of the air pump.   8. The gas pressure in the storage tank is set within an allowable operating pressure range of the liquid pump when the liquid pump and the air pump are simultaneously operated. Filtration concentration method.