JP6811162B2 - Water treatment method and equipment - Google Patents

Description

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

Generally, in a coal-fired power plant lifting facility, coal as fuel is transported from a coal storage yard to a mill using a conveyor, and pulverized coal crushed by the mill is supplied to a burner of a boiler and burned. It has become like.

Water is sprinkled on the conveyor in order to suppress spontaneous combustion due to a rise in the temperature of coal during transportation, to suppress diffusion of pulverized coal to the surroundings, and to maintain the function of the conveyor itself.

FIG. 4 is an overall schematic configuration diagram showing a conventional example of a conveyor cleaning facility in a coal lifting facility.

In the example shown in FIG. 4, the cleaning water boosted by the sprinkler pump 10 is sprinkled from a sprinkler nozzle (not shown) to the required locations of the conveyor C as a plurality of devices to perform cleaning, and the cleaning is performed. Washing water containing pulverized coal as a substance is collected in the drainage recovery tank 20, and the washing water collected in the drainage recovery tank 20 is sent to the recovery water collecting tank 40 by the recovery pump 30, and the recovery water collecting tank It is designed to be sent from 40 to the coagulation processing unit 50. In the washing water sent to the coagulation treatment unit 50, after the pulverized coal is coagulated, the washing water of the supernatant is guided to the sprinkler pump 10 through the treatment water tank 60 and is reused for sprinkling washing. This is done and this operation is repeated.

As shown in FIG. 5, the agglutination treatment unit 50 includes a pH adjusting tank 51, an agglutination reaction tank 52, and a coagulation sedimentation tank 53.

In the example shown in FIG. 5, in the pH adjusting tank 51, a coagulant such as Poly Aluminum Chloride (PAC) is added to the washing water and stirred by the stirrer 70, while the pH is adjusted to the neutral range. Aggregate flocs of turbid substances are formed, and a flocculant such as a polymer is further added in the agglutination reaction tank 52 and stirred by a stirrer 71, so that the aggregate flocs are enlarged. After that, the washing water containing the enlarged aggregate flocs is coagulated and settled while being stirred by the stirrer 72 in the coagulation and settling tank 53, and the supernatant wash water is reused. The pulverized coal (substance to be cleaned) that has been agglomerated and concentrated in the coagulation sedimentation tank 53 is extracted from the bottom of the coagulation sedimentation tank 53 by the coagulation sludge pump 80 and recovered.

In addition, there is, for example, Patent Document 1 as a thing which shows the general technical level which is related to the conveyor washing water treatment of a coal unloading facility using coagulation sedimentation as described above.

Japanese Unexamined Patent Publication No. 9-85255

However, in the case of coagulation sedimentation as described above, if the amount of the coagulant added is insufficient, the pulverized coal remains in the recycled washing water in the pulverized coal-containing wastewater having a large change in flow rate and water quality, and the washing water is used. There was a risk of clogging of the injection nozzle and wear of the piping.

On the contrary, if the amount of the coagulant added is excessive, the coagulant remains in the reused washing water, and the coagulant coagulates in the pipe, which may block the pipe.

Further, the agglomerated and concentrated pulverized coal is an agglomerate substance of a metal oxide derived from a coagulant and a floc of the pulverized coal, and has a problem that the processing cost is high because it occupies a large volume. Was.

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

Membrane treatment with a porous membrane as described above is a very effective means, but when special drainage such as wash water containing pulverized coal is targeted, the flow velocity of the wash water passing through the porous membrane Studies by the present inventors have clarified that the decrease becomes remarkable, leading to irreversible blockage of the porous membrane, making it difficult to regenerate the porous membrane, and having to stop the operation.

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 an apparatus capable of stably continuing the operation of filtering the washing water by the membrane treatment.

In order to achieve the above object, the water treatment method of the present invention includes a recovery step of washing the conveyor of the coal lifting facility and recovering the washing water containing pulverized coal which is a substance to be washed .
A membrane filtration step of filtering the washing water recovered in the recovery step with a porous membrane which is a filter obtained by stretching polytetrafluoroethylene to remove and purify the substance to be cleaned.
A reuse step of reusing the washing water purified in the membrane filtration step, and
It has a regeneration step of cleaning the porous membrane with caustic soda when the amount of permeated water of the porous membrane from which the substance to be cleaned has been removed in the membrane filtration step becomes equal to or less than a set value.

In the water treatment method, as a preliminary step of the regeneration step,
A backwashing step of periodically backwashing the porous membrane and
It is possible to have a surface cleaning step of cleaning the surface of the porous membrane backwashed in the backwashing step.

In the water treatment method, it is possible to have a sedimentation step of guiding the cleaning water of the supernatant to the membrane filtration step after sedimenting the substance to be cleaned contained in the cleaning water recovered in the recovery step.

On the other hand, the water treatment apparatus of the present invention includes a membrane treatment tank that cleans the conveyor of the coal lifting facility and introduces cleaning water containing pulverized coal as a substance to be cleaned .
A porous membrane which is a filter obtained by stretching polytetrafluoroethylene, which is arranged inside the membrane treatment tank and filters the washing water to remove and purify the substance to be washed.
The membrane treatment unit is provided with a chemical cleaning tank for cleaning the porous membrane with a chemical when the amount of permeated water of the porous membrane becomes equal to or less than a set value.

In the water treatment apparatus, the membrane treatment unit is
A backwash unit that backwashes the porous membrane and
A surface cleaning unit for cleaning the surface of the porous membrane backwashed by the backwashing unit can be provided.

In the water treatment apparatus, the membrane treatment unit is
A settling tank installed on the upstream side of the membrane treatment tank and guiding the washing water of the supernatant on which the substance to be washed has settled to the membrane treatment tank can be provided.

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

According to the water treatment method and apparatus of the present invention, it is possible to obtain an excellent effect that the operation of filtering the washing water by the membrane treatment can be stably continued.

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 an overall schematic block diagram which shows an example of the water treatment method and apparatus of this invention. It is an overall outline block diagram which shows the conventional example of the cleaning equipment of the conveyor in a coal-lifting equipment. It is a block diagram which shows an example of the conventional coagulation processing unit.

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

1 to 3 are examples of the water treatment method and apparatus of the present invention.

As shown in FIG. 1, an example of the water treatment method of the present invention includes a recovery step (see step S10), a membrane filtration step (see step S30), and a reuse step (see step S90) as basic steps. , A regeneration step (see step S80).

The recovery step is, for example, a step of washing the conveyor C (see FIG. 3) as an equipment of the coal lifting facility and recovering the washing water containing pulverized coal as the substance to be cleaned.

The membrane filtration step is a step of filtering the washing water recovered in the recovery step with a porous membrane 130 (see FIG. 2) to remove pulverized coal and purify it.

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

The regeneration step is a step of cleaning the porous membrane 130 with a chemical when the amount of permeated water of 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. It is determined in step S70 whether or not the amount of permeated water in the porous membrane 130 from which the pulverized coal has been removed in the membrane filtration step is equal to or less than the set value.

In an example of the water treatment method of the present invention, a backwashing step (see step S50) and a surface washing step (see step S60) are included as a pre-step of the regeneration step.

The backwashing step is a step of periodically backwashing the porous membrane 130. Periodic backwashing is performed based on counting the time with a timer and determining whether or not a certain time has elapsed (see step S40 in FIG. 1).

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

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

The sedimentation step is a step of precipitating the pulverized coal contained in the washing water recovered in the recovery step and then guiding the washing water of the supernatant to the membrane filtration step.

An example of the water treatment apparatus of the present invention is shown in FIG. 2, and includes a membrane treatment unit 100 having a membrane treatment tank 120, a porous membrane 130, and a chemical cleaning tank 140.

In the membrane treatment tank 120, the conveyor C (equipment) is washed and cleaning water containing pulverized coal (substance to be cleaned) is introduced. At the bottom of the membrane treatment tank 120, a filtration aeration nozzle 151 for injecting air supplied from the filtration aeration blower 150 is arranged.

The porous membrane 130 is arranged above the filtration aeration nozzle 151 inside the membrane treatment tank 120 so as to filter the washing water to remove and purify pulverized coal. A filtration line 160 that sucks up the filtered washing water is connected to the upper end of the porous membrane 130, and the filtration line 160 is provided with a filtration pump 161. The pulverized coal (substance to be cleaned) 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 recovered.

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

The membrane treatment unit 100 includes a backwash unit 190 that backwashes the porous membrane 130 with water, and a surface cleaning unit 200 that cleans the surface of the porous membrane 130 backwashed by the backwash unit 190. ing. The backwash unit 190 includes a backwash line 191 connected in the middle of the filtration line 160, a backwash pump 192 connected to the backwash line 191 to supply backwash water, and a backwash line 191 in the middle. A backwash valve 193 provided in the above and a controller 195 that periodically outputs an open signal 194 to the backwash valve 193 are provided. The backwash unit 190 may replace the backwash pump 192 with a blower and perform backwash with air instead of water.

Further, the membrane treatment unit 100 includes a settling tank 110 installed on the upstream side of the membrane treatment tank 120 and guiding the washing water of the supernatant on which the pulverized coal is settled to the membrane treatment tank 120. Inside the settling tank 110, a baffle plate 111 is provided to prevent the washing water from being short-cut and led out to the membrane treatment tank 120 before the pulverized coal settles. The pulverized coal (substance to be cleaned) settled in the settling tank 110 is extracted from the bottom of the settling tank 110 by a settling sludge pump 210 and recovered.

Then, as the porous membrane 130, a filter obtained by stretching polytetrafluoroethylene (PTFE) is adopted.

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

In an example of the water treatment apparatus of the present invention, as shown in FIG. 3, the device is a conveyor C of a coal lifting facility, and the substance to be cleaned is pulverized coal, but a plurality of the conveyors C are arranged. The film processing unit 100 is distributed and deployed for each conveyor C. The required parts of the conveyor C are cleaned by sprinkling the cleaning water purified by the membrane treatment unit 100 and boosted by the watering pump 220 from a watering nozzle (not shown). There is.

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

First, as shown in FIG. 3, for example, the washing water boosted by the watering pump 220 is sprinkled from a watering nozzle (not shown) to a required part of the conveyor C as an equipment of a coal lifting facility to perform cleaning. Will be done. At this time, the washing water containing pulverized coal as the substance to be washed is recovered (see "Recovery Step" in step S10 of FIG. 1).

The washing water recovered in the recovery step is sent to the membrane treatment unit 100. In the membrane treatment unit 100, first, the pulverized coal contained in the washing water is settled in the settling tank 110 (see “Settlement step” in step S20 of FIG. 1). Here, since the baffle plate 111 is provided inside the settling tank 110, it is possible to prevent the washing water from being short-cut and led out to the membrane treatment tank 120 before the pulverized coal settles. The pulverized coal (substance to be cleaned) settled in the settling tank 110 is extracted from the bottom of the settling tank 110 by a settling sludge pump 210 and recovered. The washing water of the supernatant in which the pulverized coal is settled is guided to the membrane treatment tank 120.

As the settling step, the supernatant washing water in which the pulverized coal contained in the washing water is settled in the settling tank 110 is guided to the membrane treatment tank 120. In the membrane treatment tank 120, the air boosted by the filtration aeration blower 150 is ejected from the filtration aeration nozzle 151, and the washing water is discharged from the porous membrane 130 arranged above the filtration aeration nozzle 151. It is filtered to remove pulverized coal and purified (see "Membrane Filtration Step" in step S30 of FIG. 1). The wash 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 cleaned) 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 recovered.

The cleaning water filtered and purified in the membrane treatment tank 120 as the membrane filtration step is pressurized by the watering pump 220 shown in FIG. 3 and sprinkled from a watering nozzle (not shown) to clean the conveyor C (not shown). See "Reuse Step" in step S90 of FIG. 1).

Then, while the recovery step, the sedimentation step, the membrane filtration step, and the reuse step are performed, the time is counted by the timer, and it is determined whether or not a certain time has elapsed (see step S40 in FIG. 1). After a certain period of time has elapsed, the controller 195 of the backwash unit 190 shown in FIG. 2 outputs an open signal 194 to the backwash valve 193, and the porous membrane 130 is connected to the backwash line 191 from the backwash pump 192. It is backwashed with water supplied through the filtration line 160 (see "Backwashing Step" in step S50 of FIG. 1). During the backwash, the filtration pump 161 is stopped. 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. 1). As a result, the clogging of the porous membrane 130 is eliminated. After the backwash is completed, the backwash valve 193 is closed.

However, as the operation is continued, clogging of the porous membrane 130, which cannot be completely removed by backwashing alone, also occurs. Therefore, it is determined whether or not the amount of permeated water in the porous membrane 130 is equal to or less than the set value (see step S70 in FIG. 1). When the amount of permeated water in the porous membrane 130 is equal to or less than a set value, the porous membrane 130 is taken out from the membrane treatment tank 120 and transferred to the chemical cleaning tank 140. An aqueous solution of caustic soda is stored in the chemical cleaning tank 140, and air boosted by the regenerative aeration blower 180 is injected from the regenerative aeration nozzle 181. By immersing the porous membrane 130 in an aqueous solution of caustic soda and aerating it, the porous membrane 130 is regenerated (see "Regeneration Step" in Step S80 of FIG. 1).

Here, if cellulose acetate, polyethylene, polyacrylonitrile, polysulfone, polyethersulfone, polyamide, polyvinyl alcohol, polyvinylidene fluoride or the like is used as the porous membrane 130, durability and chemical resistance are sufficient. Therefore, if caustic soda is used as a chemical, it is difficult to continue the operation of filtering the washing water to remove pulverized coal and purifying it.

However, in an example of the water treatment method and apparatus of the present invention, since the porous membrane 130 is a filter obtained by stretching polytetrafluoroethylene, it is excellent in durability and chemical resistance, and cleaning water containing pulverized coal is used. Even when such special drainage is targeted, it is possible to prevent a decrease in the flow velocity of the washing water passing through the porous membrane 130 and prevent irreversible blockage of the porous membrane 130. The porous membrane 130 can be regenerated, and the operation can proceed smoothly without stopping.

In this way, the operation of filtering the washing water by the membrane treatment can be stably continued.

Then, in an example of the water treatment method of the present invention, as a preliminary step of the regeneration step, a backwash step of periodically backwashing the porous membrane 130 and a backwashing of the porous membrane in the backwash step are performed. It has a surface cleaning step of cleaning the surface of 130. Further, in an example of the water treatment apparatus of the present invention, the membrane treatment unit 100 includes a backwash unit 190 that backwashes the porous membrane 130 and a porous membrane 130 that is backwashed by the backwash unit 190. It is provided with a surface cleaning unit 200 for cleaning the surface. With such a configuration, the time until regeneration of the porous membrane 130 by the drug can be extended, which is effective.

An example of the water treatment method of the present invention has a settling step of precipitating the substance to be washed contained in the washing water recovered in the recovery step and then guiding the washing water of the supernatant to the membrane filtration step. .. Further, in an example of the water treatment apparatus of the present invention, the membrane treatment unit 100 is installed on the upstream side of the membrane treatment tank 120, and the supernatant cleaning water in which the substance to be cleaned is precipitated is sent to the membrane treatment tank 120. The settling tank 110 for guiding is provided. With this configuration, pulverized coal called amorphous carbon (amorphous carbon), which has a special behavior, can be separated and removed in advance before being filtered by the membrane treatment unit 100, and can be separated by the membrane treatment unit 100. Efficiency can be increased.

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

In an example of the water treatment method and apparatus of the present invention, the agent is caustic soda. With this configuration, the porous membrane 130 made of a filter obtained by stretching polytetrafluoroethylene can be efficiently regenerated.

In an example of the water treatment apparatus of the present invention, the apparatus is a conveyor C of a coal lifting facility, and the substance to be cleaned is pulverized coal. With this configuration, unlike the coagulation sedimentation by the coagulant used for treating the washing water of the conventional conveyor C, the pulverized coal does not remain in the washing water due to the insufficient amount of the coagulant added. There is no clogging of the nozzle that injects cleaning water or wear of the piping. Of course, the coagulant does not remain in the recycled washing water due to the excessive addition amount of the coagulant, and there is no concern that the coagulant is agglomerated in the pipe or the pipe is clogged. Further, since the pulverized coal is neither agglomerated nor concentrated, the metal oxide derived from the aggregating agent and the floc agglomerate of the pulverized coal are not generated, and the processing cost thereof can be avoided.

In an example of the water treatment apparatus of the present invention, a plurality of the conveyors C are arranged, and the membrane treatment units 100 are distributed and arranged for each of the conveyors C. With this configuration, the overall operating efficiency is improved as compared with the case where the washing water recovered from the conveyors C arranged in a plurality of units is intensively treated by the coagulation treatment unit 50 as in the conventional example shown in FIG. , Cost reduction can be achieved.

Hereinafter, examples of the water treatment method and apparatus of the present invention will be shown.

First, when the porous membrane 130 is washed with a chemical and regenerated, a porous membrane made of polytetrafluoroethylene (PTFE) (Poaflon (registered trademark): manufactured by Sumitomo Electric) and polyvinylidene fluoride (PVDF) are used. In parallel with the porous membrane (Stellapore (registered trademark): manufactured by Mitsubishi Chemical Co., Ltd.), the conveyor C (equipment) was washed and the washing water containing pulverized coal (substance to be cleaned) (exhausted raw water: analytical values are shown in [Table]. (See 1]) was passed through the liquid, the conversion values per equivalent membrane area were compared, and the changes in each differential pressure over time were observed. As a result, the results shown in [Table 2] were obtained.

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

For the porous membrane made of polytetrafluoroethylene (PTFE), the calculated value of the actual permeation flux decreased to 72 [%] after 120 hours, and for the porous membrane made of polyvinylidene fluoride (PVDF). After 96 hours, the calculated value of the actual permeation flux decreased to 68 [%], and each of them was subjected to a regeneration test by chemical washing.

Prior to the regeneration test, the backwash of the porous membrane was carried out with tap water.

As a condition for backwashing with tap water, a flux is used.
3 [m ³ / (m ²・ Day) ＝ 125 [L / h]
The time was set to 5 minutes.

The results are shown in [Table 3].

Following the backwash with tap water, a porous membrane made of polytetrafluoroethylene (PTFE) and a porous membrane made of polyvinylidene fluoride (PVDF) were used as chemicals (citric acid, sodium hypochlorite, caustic soda). Was washed and regenerated.

The citric acid washing was carried out according to the following procedure.
1. 1. After backwashing with tap water, the inside of the water tank was filled with 0.5 [%] citric acid solution, and the aeration blower for filtration was continuously operated.
The immersion treatment was carried out for 2.8 hours or more.
3. 3. The citric acid solution was discarded, the conveyor C (equipment) was washed and replaced with washing water (exhaust raw water) containing pulverized coal (substance to be cleaned), and the pH was adjusted to 6 or higher.
4. The liquid was passed under steady filtration conditions.

Sodium hypochlorite washing was performed according to the following procedure.
1. 1. After backwashing with tap water, the inside of the water tank was filled with 0.05 [%] sodium hypochlorite solution, and the aeration blower for filtration was continuously operated.
The immersion treatment was carried out for 2.8 hours or more.
3. 3. The sodium hypochlorite solution was discarded, the conveyor C (equipment) was washed and replaced with washing water (exhaust raw water) containing pulverized coal (substance to be cleaned), and the pH was adjusted to 8 or less.
4. The liquid was passed under steady filtration conditions.

The caustic soda washing was carried out by the following procedure.
1. 1. After backwashing with tap water, the inside of the water tank was filled with 10 [%] caustic soda solution, and the aeration blower for filtration was continuously operated.
The immersion treatment was carried out for 2.8 hours or more.
3. 3. The caustic soda solution was discarded, the conveyor C (equipment) was washed and replaced with washing water (exhaust raw water) containing pulverized coal (substance to be cleaned), and the pH was adjusted to 8 or less.
4. The liquid was passed under steady filtration conditions.

The regeneration results by the above chemical washing are shown in [Table 4].

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

Incidentally, the porous film made of polyvinylidene fluoride (PVDF) had a light brown surface. That is, it was found that the porous membrane made of polyvinylidene fluoride (PVDF) tends to be vulnerable to caustic soda.

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

The water treatment method and apparatus of the present invention are not limited to the above-mentioned examples and examples, and can be applied to other than cleaning conveyors in coal-fired power plant lifting facilities, etc. Of course, various changes can be made without departing from the gist of the present invention.

100 Membrane treatment unit 110 Sedimentation tank 120 Membrane treatment tank 130 Porous membrane 140 Chemical cleaning tank 190 Backwash unit 200 Surface cleaning unit C Conveyor (equipment)

Claims (7)

A recovery process that cleans the conveyor of the coal lifting facility and recovers the washing water containing pulverized coal , which is the substance to be cleaned .
A membrane filtration step of filtering the washing water recovered in the recovery step with a porous membrane which is a filter obtained by stretching polytetrafluoroethylene to remove and purify the substance to be cleaned.
A reuse step of reusing the washing water purified in the membrane filtration step, and
A water treatment method comprising a regeneration step of washing the porous membrane with caustic soda when the amount of permeated water of the porous membrane from which the substance to be cleaned has been removed in the membrane filtration step becomes equal to or less than a set value. As a preliminary step to the regeneration process,
A backwashing step of periodically backwashing the porous membrane and
The water treatment method according to claim 1, further comprising a 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 precipitating the substance to be cleaned contained in the wash water recovered in the recovery step and then guiding the wash water of the supernatant to the membrane filtration step. A membrane treatment tank that cleans the conveyor of the coal lifting facility and introduces cleaning water containing pulverized coal , which is the substance to be cleaned ,
A porous membrane which is a filter obtained by stretching polytetrafluoroethylene, which is arranged inside the membrane treatment tank and filters the washing water to remove and purify the substance to be washed.
A water treatment apparatus including a membrane treatment unit having a chemical cleaning tank for cleaning the porous membrane with caustic soda when the amount of permeated water in the porous membrane becomes equal to or less than a set value. The membrane processing unit is
A backwash unit that backwashes the porous membrane and
The water treatment apparatus according to claim 4, further comprising a surface cleaning unit for cleaning the surface of the porous membrane backwashed by the backwashing unit. The membrane processing unit is
The water treatment apparatus according to claim 4 or 5 , further comprising a settling tank installed on the upstream side of the membrane treatment tank and guiding the washing water of the supernatant on which the substance to be cleaned is settled to the membrane treatment tank. The water treatment apparatus according to any one of claims 4-6 , wherein a plurality of the conveyors are arranged and the membrane treatment units are distributed and arranged for each conveyor.

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