WO2019097767A1

WO2019097767A1 - Method and device for water treatment

Info

Publication number: WO2019097767A1
Application number: PCT/JP2018/027986
Authority: WO
Inventors: 津田　隆; 大助大森; 昭洋田中; 雅典東都; 雄川上; 翔御手洗
Original assignee: Ｉｈｉ運搬機械株式会社; 協和機電工業株式会社
Priority date: 2017-11-20
Filing date: 2018-07-25
Publication date: 2019-05-23
Also published as: CN111417597A; JP2019093320A; JP6811162B2

Abstract

This method for water treatment comprises: a recovery step for recovering washing water that has been used for washing a device and that contains flushed-out substances; a membrane filtration step for cleaning the washing water recovered in the recovery step by filtering out and removing the flushed-out substances using a porous membrane; a reuse step for reusing the washing water cleaned in the membrane filtration step; and a regeneration step for washing the porous membrane using a chemical agent when the permeate flow rate of the porous membrane, which has been used to remove the flushed-out substances in the membrane filtration step, becomes equal to or lower than a set value, wherein the porous membrane is a filter obtained by stretching a polytetrafluoroethylene, and the chemical agent is caustic soda.

Description

Water treatment method and apparatus

The present invention relates to a water treatment method and apparatus.

In general, in a coal transportation facility of a coal thermal power plant, coal serving as fuel is transported from a coal storage station to a mill using a conveyor, and pulverized coal pulverized in the mill is supplied to a burner of a boiler and burned. It is supposed to be.

Sprinkling is performed to the above-mentioned conveyor for the control of the spontaneous combustion with the temperature rise of coal under conveyance, the control of diffusion of the pulverized coal to the circumference, and maintenance of the function of the conveyor itself.

FIG. 1 is a whole schematic block diagram showing an example of a conventional cleaning equipment of a conveyor in a lifting coal equipment.

In the example shown in FIG. 1, the washing water pressurized by the water pouring pump 10 is sprinkled from a water sprinkling nozzle (not shown) to the conveyor C as a plurality of devices and the washing is performed, and the fine powder as the substance to be washed Wash water containing charcoal is collected in the drainage recovery tank 20, and the wash water collected in the drainage recovery tank 20 is supplied to the collection water collecting tank 40 by the collection pump 30, and aggregation treatment is carried out from the collection water collecting tank 40. It is sent to the unit 50. The washing water sent to the aggregation treatment unit 50 is subjected to aggregation treatment of pulverized coal, and then the supernatant washing water is led to the water distribution pump 10 through the treatment water tank 60 and is reused in the form of being reused. It is done and this operation is to be repeated.

The aggregation treatment unit 50 includes a pH adjustment tank 51, an aggregation reaction tank 52, and an aggregation sedimentation tank 53, as shown in FIG.

In the example shown in FIG. 2, a coagulant such as poly aluminum chloride (PAC: Poly Aluminum Chloride) is added to the washing water in the pH adjustment tank 51, and the mixture is stirred by the stirrer 70 to adjust the pH to a neutral range. An aggregate floc of suspended matter is formed, and further, an aggregating agent such as a polymer is added in the agglutination reaction tank 52, and the aggregate floc is enlarged by being stirred by the agitator 71. Thereafter, the washing water containing the enlarged aggregate floc is coagulated and precipitated while being stirred by the stirrer 72 in the coagulation sedimentation tank 53, and the supernatant washing water is reused. The pulverized coal (substance to be washed) which is coagulated and concentrated in the coagulating settling tank 53 is extracted from the bottom of the coagulating settling tank 53 by the coagulated sludge pump 80 and is recovered and processed.

In addition, there exists patent document 1 as an example which shows the general technical level relevant to the conveyor washing water treatment of the lifting and hauling coal installation which utilized the above-mentioned aggregation sedimentation.

JP-A-9-85255

However, in the case of coagulated sedimentation as described above, when the addition amount of the coagulant is insufficient, pulverized coal-containing drainage with a large amount of pulverized coal-containing drainage whose flow rate and water quality change is large remains pulverized coal and is used as cleaning water. There is a possibility that clogging of the jet nozzle and abrasion of the piping may occur.

On the contrary, when the addition amount of the coagulant is excessive, the coagulant remains in the recycled washing water, and the coagulant may be coagulated in the pipe, and the pipe may be clogged.

In addition, the agglomerated and concentrated pulverized coal is an agglomerated material of metal oxide derived from flocculant and floc of pulverized coal, and occupies a large volume, so that there is a problem that the processing cost becomes high. Was.

In order to solve these problems, the present inventors have found that porous membranes of various materials, for example, cellulose acetate (CA: Cellulose Acetate), polyethylene (PE: Polyethylene), polyacrylonitrile (PAN: Polyacrylonitrile), polysulfone ( PS: Polysulfone), polyethersulfone (PES: Polyethersulfone), polyamide (PA: Polyamide), polyvinyl alcohol (PVA: Polyvinyl Alcohol), polyvinylidene fluoride (PVDF: Polyvinylidene Difluoride) etc., and washing water is filtered It is proposed to remove and purify pulverized coal.

While the membrane treatment with the porous membrane as described above is a very effective means, when special drainage such as washing water containing pulverized coal is targeted, the flow velocity of the washing water passing through the porous membrane is It has become clear from the studies of the present inventors that the decrease is remarkable, which leads to irreversible plugging of the porous membrane, which makes it difficult to regenerate the porous membrane and the operation has to be stopped.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a water treatment method and apparatus capable of stably continuing the operation of filtering washing water by membrane treatment.

In order to achieve the above object, the water treatment method of the present invention comprises a recovery step of washing equipment and recovering wash water containing a substance to be washed;
A membrane filtration step of filtering the cleaning water recovered in the recovery step with a porous membrane to remove and purify the substance to be cleaned;
A recycling step of recycling the cleaning water purified in the membrane filtration step;
And a regeneration step of washing the porous membrane with a drug when the amount of permeated water of the porous membrane from which the substance to be washed has been removed in the membrane filtration step becomes equal to or less than a set value.

In the water treatment method, as a step before the regeneration step,
A backwashing step of periodically backwashing the porous membrane;
And a surface cleaning step of cleaning the surface of the porous membrane backwashed in the backwashing step.

The water treatment method may include a sedimentation step of leading the washing water of the supernatant to the membrane filtration step after settling the substance to be washed contained in the washing water recovered in the recovery step.

In the water treatment method, the porous membrane can be a filter formed by stretching polytetrafluoroethylene.

In the water treatment method, the agent can be caustic soda.

In the water treatment method, the device may be a conveyor of a lifting coal facility, and the to-be-cleaned material may be pulverized coal.

On the other hand, in the water treatment apparatus of the present invention, there is provided a membrane treatment tank into which washing water containing a substance to be washed is introduced.
A porous membrane disposed inside the membrane treatment tank and filtering the washing water to remove and purify the substance to be washed;
And the chemical | medical solution cleaning tank which wash | cleans the said porous membrane by a chemical | medical agent, when the water permeation amount of this porous membrane becomes below in a setting value.

In the water treatment apparatus, the membrane treatment unit is
A backwashing unit for backwashing the porous membrane;
And a surface cleaning unit for cleaning the surface of the porous membrane backwashed by the backwashing unit.

In the water treatment apparatus, the membrane treatment unit is
It is possible to provide a sedimentation tank which is installed on the upstream side of the membrane processing tank and guides the washing water of the supernatant obtained by settling the substance to be washed to the membrane processing tank.

In the water treatment apparatus, the porous membrane can be a filter formed by drawing polytetrafluoroethylene.

In the water treatment device, the agent may be caustic soda.

In the water treatment apparatus, the device may be a conveyor of lifting coal equipment, and the material to be cleaned may be pulverized coal.

In the water treatment apparatus, a plurality of the conveyors can be provided, and the membrane treatment units can be distributed and provided for each of the conveyors.

ADVANTAGE OF THE INVENTION According to the water treatment method and apparatus of this invention, the outstanding effect that the driving | operation which filters wash water by membrane treatment can be continued stably can be produced.

It is a whole schematic block diagram which shows an example of the former of the washing | cleaning installation of the conveyor in a lift transportation charcoal installation. It is a block diagram which shows an example of the conventional aggregation process unit. It is a flowchart which shows an example of the water treatment method and apparatus of this invention. It is a block diagram which shows the membrane treatment unit in an example of the water treatment method and apparatus of this invention. It is a whole outline block diagram which shows an example of the water treatment method and apparatus of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

3 to 5 show an example of the water treatment method and apparatus of the present invention.

One example of the water treatment method of the present invention is, as shown in FIG. 3, as a basic step, a recovery step (see step S10), a membrane filtration step (see step S30), and a reuse step (see step S90). And the regeneration step (see step S80).

The recovery step is, for example, a step of cleaning a conveyor C (see FIG. 5) as an apparatus for lifting and transporting coal and recovering cleaning water containing pulverized coal as a substance to be cleaned.

The membrane filtration step is a step of filtering the cleaning water recovered in the recovery step with the porous membrane 130 (see FIG. 4) to remove pulverized coal and purify it.

The reuse step is a step of reusing the cleaning water purified in the membrane filtration step.

The regeneration step is a step of washing the porous membrane 130 with a drug when the amount of water permeated from the porous membrane 130 from which pulverized coal has been removed in the membrane filtration step becomes equal to or less than a set value. The determination as to whether or not the amount of permeated water of the porous membrane 130 from which pulverized coal has been removed in the membrane filtration step has become equal to or less than a set value is made in step S70.

In an example of the water treatment method according to the present invention, a backwashing step (see step S50) and a surface cleaning step (see step S60) are included as steps before the regeneration step.

The backwashing step is a step of periodically backwashing the porous membrane 130. The periodic backwashing is performed by counting time with a timer and determining whether or not a predetermined time has elapsed (see step S40 in FIG. 3).

The surface cleaning step is a step of cleaning the surface of the porous membrane 130 backwashed in the backwashing step.

Furthermore, in an example of the water treatment method of the present invention, a sedimentation step (see step S20) is included between the recovery step and the membrane filtration step.

The sedimentation step is a step of guiding the supernatant wash water to the membrane filtration step after settling pulverized coal contained in the wash water recovered in the recovery step.

An example of the water treatment apparatus of the present invention is shown in FIG. 4 and comprises a membrane treatment unit 100 having a membrane treatment tank 120, a porous membrane 130, and a drug washing tank 140.

The film processing tank 120 cleans the conveyor C (equipment) so that cleaning water containing pulverized coal (substance to be cleaned) is introduced. At the bottom of the membrane processing tank 120, a filtration aeration nozzle 151 for injecting the air supplied from the filtration aeration blower 150 is disposed.

The porous membrane 130 is disposed at a position above the filtration aeration nozzle 151 inside the membrane processing tank 120 so as to filter the cleaning water and remove and purify pulverized coal. At the upper end of the porous membrane 130, a filtration line 160 for sucking up the filtered washing water is connected, and a filtration pump 161 is provided at the filtration line 160. The pulverized coal (substance to be washed) separated in the membrane treatment tank 120 is extracted from the bottom of the membrane treatment tank 120 by a separation sludge pump 170 and is recovered and processed.

The drug washing tank 140 is a tank for taking out the porous membrane 130 from the membrane treatment tank 120 and washing with a drug when the amount of permeated water of the porous membrane 130 becomes equal to or less than a set value. At the bottom of the medicine cleaning tank 140, a regeneration aeration nozzle 181 for injecting the air supplied from the regeneration aeration blower 180 is disposed.

The membrane processing unit 100 includes a backwashing unit 190 for backwashing the porous membrane 130 with water, and a surface cleaning unit 200 for cleaning the surface of the porous membrane 130 backwashed by the backwashing unit 190. ing. The backwashing unit 190 includes a backwashing line 191 connected to the middle of the filtration line 160, a backwashing pump 192 connected to the backwashing line 191 and supplying backwashing water, and a middle of the backwashing line 191. And a controller 195 which periodically outputs an open signal 194 to the backwash valve 193. The backwashing unit 190 may replace the backwashing pump 192 with a blower and perform backwashing with air instead of water.

Furthermore, the film processing unit 100 is provided with a sedimentation tank 110 installed on the upstream side of the film processing tank 120 and guiding the cleaning water of the supernatant obtained by settling the pulverized coal to the film processing tank 120. Inside the settling tank 110, a baffle plate 111 is provided for preventing the cleaning water from being short-cut and led to the membrane processing tank 120 before the pulverized coal settles. The pulverized coal (substance to be washed) settled in the sedimentation tank 110 is extracted from the bottom of the sedimentation tank 110 by a sedimentation sludge pump 210 and is recovered and processed.

And, as the porous membrane 130, a filter obtained by drawing and processing polytetrafluoroethylene (PTFE: Polytetrafluoroethylene) is adopted.

In addition, as the chemical, when the porous membrane 130 is a filter formed by stretching polytetrafluoroethylene, caustic soda (NaOH) can be used. The concentration of the aqueous solution of caustic soda can be set to 1% to 10%.

In an example of the water treatment apparatus according to the present invention, the equipment is a conveyor C of a lifting coal facility as shown in FIG. 5 and the substance to be cleaned is pulverized coal, but a plurality of conveyors C are provided The film processing units 100 are distributed and disposed for each of the conveyors C. For the conveyor C, the cleaning water purified by the membrane processing unit 100 and pressurized by the water spray pump 220 is sprayed from a water spray nozzle (not shown) to perform cleaning.

Next, the operation of an example of the water treatment method and apparatus will be described.

First, as shown in FIG. 5, for example, with respect to a conveyor C as a machine of a coal transportation facility, cleaning water pressurized by a water distribution pump 220 is sprayed from a sprinkle nozzle (not shown) to perform cleaning. At this time, washing water containing pulverized coal as a substance to be washed is recovered (see "recovery step" in step S10 of FIG. 3).

The wash water recovered in the recovery step is sent to the membrane processing unit 100. In the film processing unit 100, first, pulverized coal contained in the washing water is sedimented in the sedimentation tank 110 (see "sedimentation process" in step S20 of FIG. 3). Here, since the baffle plate 111 is provided inside the settling tank 110, it is prevented that the cleaning water is short-cut and led out to the membrane processing tank 120 before the pulverized coal settles. The pulverized coal (substance to be washed) sedimented in the sedimentation tank 110 is extracted from the bottom of the sedimentation tank 110 by a sedimentation sludge pump 210 and is recovered and processed. The wash water of the supernatant obtained by settling the pulverized coal is introduced to the membrane treatment tank 120.

The wash water of the supernatant obtained by settling the pulverized coal contained in the washing water in the sedimentation tank 110 as the sedimentation step is led to the membrane treatment tank 120. In the membrane processing tank 120, the air pressurized by the filtration aeration blower 150 is injected from the filtration aeration nozzle 151, and the washing water is a porous membrane 130 disposed above the filtration aeration nozzle 151. It is filtered to remove pulverized coal and purified (see "membrane filtration step" in step S30 of FIG. 3). The washing water filtered by the porous membrane 130 is sucked up from the filtration line 160 by the filtration pump 161. The pulverized coal (substance to be washed) separated in the membrane treatment tank 120 is extracted from the bottom of the membrane treatment tank 120 by the separation sludge pump 170 and is recovered.

The wash water filtered and purified in the membrane treatment tank 120 as the membrane filtration step is pressurized by a water spray pump 220 shown in FIG. 5 and sprayed from a water spray nozzle (not shown) to clean the conveyor C ( Refer to the "reuse step" in step S90 of FIG.

Then, while the recovery step, the settling step, the membrane filtration step, and the reuse step are performed, the timer counts time, and it is determined whether a predetermined time has elapsed (see step S40 in FIG. 3). When a predetermined time has elapsed, an open signal 194 is output from the controller 195 of the backwashing unit 190 shown in FIG. 4 to the backwashing valve 193, and the porous membrane 130 receives the backwashing line 191 from the backwashing pump 192. It backwashes with the water supplied via the filtration line 160 (refer to "backwashing process" of step S50 of FIG. 3). The filtration pump 161 is stopped during the backwashing. The surface of the backwashed porous membrane 130 is cleaned by the surface cleaning unit 200 (see “surface cleaning step” in step S60 of FIG. 3). Thus, clogging of the porous membrane 130 is eliminated. After the backwashing is completed, the backwashing valve 193 is closed.

However, as the operation continues, clogging of the porous membrane 130 which can not be removed only by backwashing also occurs. Therefore, it is determined whether the water permeability of the porous membrane 130 has become equal to or less than the set value (see step S70 in FIG. 3). When the amount of permeated water of the porous membrane 130 is equal to or less than the set value, the porous membrane 130 is taken out of the membrane treatment tank 120 and transferred to the chemical cleaning tank 140. An aqueous solution of caustic soda is stored in the medicine cleaning tank 140, and air pressurized by the regenerative aeration blower 180 is jetted from the regenerative aeration nozzle 181. The porous film 130 is regenerated by immersing the porous film 130 in an aqueous solution of caustic soda, thereby allowing regeneration of the porous film 130 (see “regeneration step” in step S80 of FIG. 3).

Here, if cellulose acetate, polyethylene, polyacrylonitrile, polysulfone, polyether sulfone, polyamide, polyvinyl alcohol, polyvinylidene fluoride and the like are temporarily used as the porous membrane 130, sufficient durability and chemical resistance can be obtained. If caustic soda is used as the drug, it is difficult to continue the operation of filtering the washing water to remove and purify the pulverized coal.

However, in one example of the water treatment method and apparatus of the present invention, since the porous membrane 130 is a filter obtained by drawing and processing polytetrafluoroethylene, it is excellent in durability and chemical resistance, and the washing water containing pulverized coal is used. Even in the case where such special drainage is targeted, it is possible to prevent in advance the lowering of the flow velocity of the washing water passing through the porous membrane 130 and to avoid leading to the irreversible clogging of the porous membrane 130, The regeneration process of the porous membrane 130 becomes possible, and the process can be smoothly advanced without stopping the operation.

Thus, the operation of filtering washing water by membrane treatment can be stably continued.

And, in one example of the water treatment method of the present invention, a backwashing step of periodically backwashing the porous membrane 130 as a step prior to the regeneration step, and a porous membrane backwashed in the backwashing step And a surface cleaning step of cleaning the surface of 130. In one example of the water treatment apparatus of the present invention, the membrane treatment unit 100 includes a backwashing unit 190 for backwashing the porous membrane 130, and a porous membrane 130 backwashed by the backwashing unit 190. And a surface cleaning unit 200 for cleaning the surface. With this configuration, the time until regeneration of the porous membrane 130 by the drug can be extended, which is effective.

In one example of the water treatment method of the present invention, it has a sedimentation step of leading the washing water of the supernatant to the membrane filtration step after settling the substance to be washed contained in the washing water recovered in the recovery step. . Further, in the example of the water treatment apparatus of the present invention, the membrane treatment unit 100 is disposed upstream of the membrane treatment tank 120, and the washing water of the supernatant obtained by settling the substance to be washed is sent to the membrane treatment tank 120. The settling tank 110 which leads is provided. According to this configuration, pulverized carbon called amorphous carbon (amorphous carbon) and having special behavior can be separated and removed in advance before filtration by the membrane processing unit 100, and separation in the membrane processing unit 100 can be performed. Efficiency can be improved.

In one example of the water treatment method and apparatus of the present invention, the porous membrane 130 is a filter formed by stretching polytetrafluoroethylene. With such a configuration, it is possible to provide the film processing unit 100 that is excellent in durability and chemical resistance and can perform regenerative processing in an advantageous manner.

In one example of the water treatment method and apparatus of the present invention, the agent is caustic soda. With this configuration, regeneration of the porous film 130 formed of a filter obtained by drawing and processing polytetrafluoroethylene can be efficiently performed.

In an example of the water treatment apparatus according to the present invention, the device is a conveyor C of a lifting coal facility, and the material to be cleaned is pulverized coal. According to this configuration, unlike the coagulant precipitation by a coagulant that has been used as the treatment of the cleaning water of the conventional conveyor C, the residual pulverized coal in the cleaning water does not occur due to the insufficient addition amount of the coagulant. There is no clogging of the nozzle that jets the washing water or abrasion of the piping. Of course, the addition amount of the coagulant does not cause the remaining of the coagulant in the recycled wash water, and there is no concern of the aggregation of the coagulant in the pipe and the clogging of the pipe. In addition, since pulverized coal is neither agglomerated nor concentrated, agglomerated material of metal oxide derived from flocculant and floc of pulverized coal is not generated, and increase in the processing cost can be avoided.

In an example of the water treatment apparatus of the present invention, a plurality of the conveyors C are provided, and the film treatment units 100 are dispersedly provided for each of the conveyors C. When configured in this manner, the overall operation efficiency is improved as compared to intensively treating the cleaning water collected from the plurality of conveyors C deployed as in the conventional example shown in FIG. Cost reduction can be achieved.

Hereinafter, the Example of the water treatment method and apparatus of this invention is shown.

First, when the porous membrane 130 is washed with a drug and regenerated, a porous membrane made of polytetrafluoroethylene (PTFE) (Poreflon (registered trademark): made by Sumitomo Electric Co., Ltd.) and polyvinylidene fluoride (PVDF) are used. Washing water (discharged raw water) containing pulverized coal (substance to be washed) by washing the conveyor C (equipment) in parallel to a porous membrane (STERAPORE (registered trademark): manufactured by Mitsubishi Chemical): 1) Pass through treatment, compare the conversion value per equivalent membrane area, and observe changes in each differential pressure over time. The results shown in Table 2 were obtained.

In the above [Table 2], as an initial setting condition, the permeation flux is
1.5 [m ³ / (m ² · Day) = 62.5 [L / h]
The set value of the differential pressure (suction pressure) reaching point is 40 [kPa].

Regarding porous membranes made of polytetrafluoroethylene (PTFE), porous membranes made of polyvinylidene fluoride (PVDF) for which the calculated value of actual permeation flux has decreased to 72 [%] after 120 hours have elapsed The thing of which the calculated value of actual permeation flux fell to 68 [%] after 96 hours passed was subjected to the regeneration test by drug cleaning.

Before carrying out the regenerative test, backwashing of the porous membrane was carried out with tap water.

As a condition of the backwashing with the tap water, flux 3 [m ³ / (m ² · Day) = 125 [L / h]
And the time was 5 minutes.

The results are as shown in [Table 3].

Following backwashing with tap water, the porous membrane made of polytetrafluoroethylene (PTFE) and the porous membrane made of polyvinylidene fluoride (PVDF) are used as a drug (citric acid, sodium hypochlorite, caustic soda) It was washed and regenerated.

Citric acid washing was performed according to the following procedure.
1. After backwashing with tap water, the water tank was filled with 0.5% citric acid solution, and the aeration blower for filtration was kept operating.
The immersion treatment was performed for 2.8 hours or more.
3. The citric acid solution was discarded, and the conveyor C (equipment) was washed and replaced with washing water (discharge raw water) containing pulverized coal (substance to be washed), and the pH was made 6 or more.
4. The solution was allowed to flow under constant filtration conditions.

The hypochlorous acid sodium cleaning was performed according to the following procedure.
1. After backwashing with tap water, the water tank was filled with 0.05% sodium hypochlorite solution, and the aeration blower for filtration was kept operating.
The immersion treatment was performed for 2.8 hours or more.
3. The hypochlorous acid soda solution was discarded, and the conveyor C (equipment) was cleaned and replaced with washing water (discharge raw water) containing pulverized coal (substance to be washed), and the pH was adjusted to 8 or less.
4. The solution was allowed to flow under constant filtration conditions.

The caustic soda wash was performed according to the following procedure.
1. After backwashing with tap water, the water tank was filled with 10% caustic soda solution, and the aeration blower for filtration was kept operating.
The immersion treatment was performed for 2.8 hours or more.
3. The caustic soda solution was discarded, and the above-mentioned conveyor C (equipment) was washed and replaced with washing water (discharge raw water) containing pulverized coal (substance to be washed) to make the pH 8 or less.
4. The solution was allowed to flow under constant filtration conditions.

The result of regeneration by the above drug cleaning is as shown in [Table 4].

The recovery rate for the initial permeation flux of 62.5 [L / h] is
100 × {1- (permeation flux after washing) / (initial permeation flux)} [%]
It asked for.

Incidentally, the porous membrane made of polyvinylidene fluoride (PVDF) was thin and brown on its surface. That is, it was found that porous membranes made of polyvinylidene fluoride (PVDF) tend to be weak to caustic soda.

And from the results of this example, it can be said that regeneration of a porous membrane made of polytetrafluoroethylene (PTFE) is extremely effective by washing with caustic soda as a drug.

In addition, the water treatment method and apparatus of the present invention are not limited to only the above-described examples and embodiments, and can be applied to cleaning of conveyors in lifting coal facilities of a coal-fired power plant etc. Of course, various changes can be made without departing from the scope of the present invention.

Reference Signs List 100 membrane processing unit 110 settling tank 120 membrane processing tank 130 porous membrane 140 chemical cleaning tank 190 reverse cleaning unit 200 surface cleaning unit C conveyor (equipment)

Claims

A recovery step of cleaning the device and recovering the cleaning water containing the substance to be cleaned;
A membrane filtration step of filtering the cleaning water recovered in the recovery step with a porous membrane to remove and purify the substance to be cleaned;
A recycling step of recycling the cleaning water purified in the membrane filtration step;
A regeneration step of washing the porous membrane with a drug when the amount of permeated water of the porous membrane from which the substance to be washed has been removed in the membrane filtration step becomes equal to or less than a set value.
As a step before the regeneration process,
A backwashing step of periodically backwashing the porous membrane;
The water treatment method according to claim 1, further comprising: surface cleaning step of cleaning the surface of the porous membrane backwashed in the backwashing step.
The water treatment method according to claim 1 or 2, further comprising a sedimentation step of leading the supernatant wash water to the membrane filtration step after settling the substance to be washed contained in the wash water recovered in the recovery step.
The water treatment method according to any one of claims 1 to 3, wherein the porous membrane is a filter formed by drawing polytetrafluoroethylene.
The water treatment method according to claim 4, wherein the agent is caustic soda.
The water treatment method according to any one of claims 1 to 5, wherein the device is a conveyor of a lifting coal facility, and the material to be cleaned is pulverized coal.
A membrane treatment tank in which washing water containing a substance to be washed is introduced by washing the device;
A porous membrane disposed inside the membrane treatment tank and filtering the washing water to remove and purify the substance to be washed;
A water treatment apparatus comprising: a membrane treatment unit comprising: a chemical washing tank for washing the porous membrane with a drug when the amount of permeated water of the porous membrane falls below a set value.
The membrane processing unit
A backwashing unit for backwashing the porous membrane;
The water treatment apparatus according to claim 7, further comprising: a surface cleaning unit that cleans the surface of the porous membrane backwashed by the backwashing unit.
The membrane processing unit
9. The water treatment apparatus according to claim 7, further comprising a sedimentation tank disposed upstream of the membrane treatment tank and guiding wash water of a supernatant obtained by settling the substance to be washed to the membrane treatment tank.
The water treatment device according to any one of claims 7 to 9, wherein the porous membrane is a filter formed by stretching polytetrafluoroethylene.
The water treatment device according to claim 10, wherein the agent is caustic soda.
The water treatment apparatus according to any one of claims 7 to 11, wherein the device is a conveyor of a lifting coal facility, and the substance to be cleaned is pulverized coal.
The water treatment apparatus according to claim 12, wherein a plurality of the conveyors are provided, and the membrane treatment units are distributed and disposed for each of the conveyors.