CN111417597A - Water treatment method and apparatus - Google Patents
Water treatment method and apparatus Download PDFInfo
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- CN111417597A CN111417597A CN201880075085.6A CN201880075085A CN111417597A CN 111417597 A CN111417597 A CN 111417597A CN 201880075085 A CN201880075085 A CN 201880075085A CN 111417597 A CN111417597 A CN 111417597A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
- B01D65/02—Membrane cleaning or sterilisation ; Membrane regeneration
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
- B01D65/02—Membrane cleaning or sterilisation ; Membrane regeneration
- B01D65/06—Membrane cleaning or sterilisation ; Membrane regeneration with special washing compositions
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/30—Polyalkenyl halides
- B01D71/32—Polyalkenyl halides containing fluorine atoms
- B01D71/36—Polytetrafluoroethene
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
- B65G45/00—Lubricating, cleaning, or clearing devices
- B65G45/10—Cleaning devices
- B65G45/22—Cleaning devices comprising fluid applying means
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
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Abstract
Comprising: a recovery step of cleaning the instrument and recovering cleaning water containing the substance to be cleaned; a membrane filtration step of filtering the washing water recovered in the recovery step with a porous membrane to remove and purify the substance to be washed; a reuse step of reusing the cleaning water purified by the membrane filtration step; and a regeneration step of cleaning the porous membrane by a chemical when the water permeation amount of the porous membrane from which the material to be cleaned has been removed in the membrane filtration step is a set value or less, the porous membrane being a filter obtained by stretching polytetrafluoroethylene, and the chemical being sodium hydroxide.
Description
Technical Field
The present invention relates to a water treatment method and apparatus.
Background
In general, in a coal handling facility of a coal thermal power plant, coal as fuel is carried from a coal yard to a coal mill by a conveyor, and pulverized coal pulverized by the coal mill is supplied to a burner of a boiler and burned.
Water is sprayed to the conveyor to suppress spontaneous combustion accompanying a rise in temperature of coal being conveyed, suppress diffusion of pulverized coal to the surroundings, and maintain the function of the conveyor itself.
Fig. 1 is an overall schematic configuration diagram showing a conventional example of a cleaning apparatus for a conveyor in a coal loading facility.
In the example shown in fig. 1, the washing water pressurized by the water jet pump 10 is jetted from the water jet nozzles (not shown) to wash a plurality of conveyors C as equipment, the washing water containing pulverized coal as a substance to be washed is collected in the effluent collection tank 20, the washing water collected in the effluent collection tank 20 is supplied to the collection water tank 40 by the collection pump 30, and the collected washing water is sent from the collection water tank 40 to the coagulation treatment unit 50. The washing water sent to the coagulation treatment unit 50 is repeatedly subjected to coagulation treatment of the pulverized coal, and then the washing water of the upper surface clarified portion of the pulverized coal is guided to the water jet pump 10 through the treatment water tank 60, and is subjected to water jet washing in a reused form.
As shown in FIG. 2, the coagulation treatment unit 50 includes a pH adjustment tank 51, a coagulation reaction tank 52, and a coagulation sedimentation tank 53.
In the example shown in FIG. 2, a flocculant such as polyaluminum chloride (PAC) is added to the washing water in the pH adjustment tank 51 and stirred by the stirrer 70 to adjust the pH to a neutral range and form polymer floc (floc) of suspended substances, and a flocculant such as a polymer is added to the coagulation reaction tank 52 and stirred by the stirrer 71 to increase the volume of the polymer floc. Subsequently, in the coagulation sedimentation tank 53, the washing water containing the polymer flocs having increased volume is coagulated and sedimented while being stirred by the stirrer 72, and the washing water of the upper clarified part is reused. The pulverized coal (cleaning target) condensed and concentrated in the coagulation sedimentation tank 53 is extracted from the bottom of the coagulation sedimentation tank 53 by a sludge coagulation pump 80 and is collected and treated.
Further, as a document showing a general technical level related to a conveyor washing water treatment of a coal handling facility utilizing the above-described coagulation sedimentation, for example, patent document 1 exists.
Prior art documents
Patent document
Patent document 1: japanese patent laid-open No. 9-85255.
Disclosure of Invention
Problems to be solved by the invention
However, in the case of the coagulation sedimentation as described above, if the amount of the coagulant added is insufficient, the pulverized coal remains in the reused cleaning water in the pulverized coal-containing drainage water having a large change in flow rate or water quality, and there is a possibility that the nozzle for spraying the cleaning water is clogged or the piping is worn.
On the other hand, if the amount of the coagulant added becomes excessive, the coagulant remains in the reused cleaning water, and the coagulant may aggregate in the pipe, thereby blocking the pipe.
Further, the pulverized coal coagulated and concentrated is a mass of flocs of the metal oxide derived from the coagulant and the pulverized coal, and occupies a large volume, and therefore, there is a problem that the treatment cost thereof becomes high.
In order to solve such a problem, the present inventors have proposed the following: the cleaning water is filtered and cleaned by removing the pulverized coal using porous membranes made of various materials, for example, Cellulose Acetate (CA), Polyethylene (PE), Polypropylene (PAN), Polysulfone (PS), Polyethersulfone (PES), Polyamide (PA), Polyvinyl Alcohol (PVA), Polyvinylidene fluoride (PVDF), etc.
As is apparent from the studies by the present inventors, the membrane treatment by the porous membrane as described above is a very effective means, and on the contrary, if special drain water such as washing water containing pulverized coal is targeted, the flow rate of the washing water passing through the porous membrane is significantly reduced, and irreversible clogging of the porous membrane is caused, and the regeneration treatment of the porous membrane becomes difficult, and the operation must be stopped.
The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a water treatment method and apparatus capable of continuing stable operation of filtering cleaning water by membrane treatment.
Means for solving the problems
In order to achieve the above object, a water treatment method of the present invention includes: a recovery step of cleaning the instrument and recovering cleaning water containing the substance to be cleaned; a membrane filtration step of filtering the washing water recovered in the recovery step with a porous membrane to remove and purify the substance to be washed; a reuse step of reusing the cleaning water purified in the membrane filtration step; and a regeneration step of cleaning the porous membrane with a chemical when the water permeation amount of the porous membrane from which the substance to be cleaned has been removed in the membrane filtration step is a set value or less.
The water treatment method may further include, as a previous stage of 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: after the substances to be cleaned contained in the cleaning water recovered in the recovery step are settled, the cleaning water in the upper clear part is guided to the membrane filtration step.
In the water treatment method, the porous membrane may be a filter obtained by stretching polytetrafluoroethylene.
In the water treatment method, the chemical may be sodium hydroxide.
In the water treatment method, the apparatus may be a conveyor of a coal handling facility, and the material to be cleaned may be pulverized coal.
In another aspect, a water treatment apparatus according to the present invention includes a membrane treatment unit including: a membrane processing tank into which cleaning water containing a substance to be cleaned is introduced; a porous membrane disposed inside the membrane treatment tank, for filtering the washing water to remove and purify the substance to be washed; and a chemical cleaning tank for cleaning the porous membrane with a chemical when the water permeation amount of the porous membrane is equal to or less than a set value.
In the water treatment apparatus, the membrane treatment unit may include: a backwashing unit that backwashes the porous membrane; and a surface cleaning unit that cleans the surface of the porous membrane backwashed by the backwashing unit.
In the water treatment apparatus, the membrane treatment unit may include: and a settling tank which is provided upstream of the membrane treatment tank and guides the washing water of the upper surface clarified portion after the substances to be washed are settled to the membrane treatment tank.
In the water treatment apparatus, the porous membrane may be a filter obtained by stretching polytetrafluoroethylene.
In the water treatment apparatus, the chemical may be sodium hydroxide.
In the water treatment apparatus, the apparatus may be a conveyor of a coal handling facility, and the material to be cleaned may be pulverized coal.
In the water treatment apparatus, the conveyor may be provided with a plurality of conveyors, and the membrane treatment unit may be disposed in a dispersed manner for each of the conveyors.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the water treatment method and apparatus of the present invention, an excellent effect of enabling the operation of filtering the cleaning water through the membrane treatment to be continuously and stably performed can be achieved.
Drawings
Fig. 1 is an overall schematic configuration diagram showing a conventional example of a cleaning apparatus for a conveyor in a coal loading facility.
Fig. 2 is a block diagram showing an example of a conventional coagulation processing unit.
FIG. 3 is a flow chart showing one example of the water treatment method and apparatus of the present invention.
FIG. 4 is a view showing the structure of a membrane treatment unit in one example of the water treatment method and apparatus of the present invention.
FIG. 5 is an overall schematic configuration diagram showing an example of the water treatment method and apparatus of the present invention.
Detailed Description
Embodiments of the present invention will be described below with reference to the drawings.
Fig. 3 to 5 are one example of the water treatment method and apparatus of the present invention.
One example of the water treatment method of the present invention includes, as basic steps, a recovery step (see step S10), a membrane filtration step (see step S30), a reuse step (see step S90), and a regeneration step (see step S80) as shown in fig. 3.
The recovery step is a step of cleaning a conveyor C (see fig. 5) as a device for transporting coal, for example, and recovering cleaning water containing pulverized coal as a substance to be cleaned.
The membrane filtration step is a step of filtering the washing water collected in the collection step by a porous membrane 130 (see fig. 4) to remove and purify the pulverized coal.
The reuse step is a step of reusing the washing water purified in the membrane filtration step.
The regeneration step is a step of washing the porous membrane 130 with a chemical when the water permeation amount of the porous membrane 130 from which the pulverized coal has been removed in the membrane filtration step is a set value or less. The determination as to whether or not the water permeation amount of the porous membrane 130 from which the fine coal has been removed by the membrane filtration step is equal to or less than the set value is performed in step S70.
In one example of the water treatment method of the present invention, a backwashing step (see step S50) and a surface cleaning step (see step S60) are provided as the previous stages of the regeneration step.
The backwashing step is a step of periodically backwashing the porous membrane 130. The regular backwashing is performed by counting time with a timer and determining whether 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.
In one example of the water treatment method of the present invention, a settling step is provided between the recovery step and the membrane filtration step (see step S20).
The settling step is a step of settling the fine coal included in the cleaning water recovered in the recovery step, and then guiding the cleaning water in the upper-surface clarified portion to the membrane filtration step.
An example of the water treatment apparatus of the present invention includes a membrane treatment unit 100 shown in fig. 4, and the membrane treatment unit 100 includes a membrane treatment tank 120, a porous membrane 130, and a chemical cleaning tank 140.
The membrane treatment tank 120 cleans the conveyor C (equipment) and is supplied with cleaning water containing pulverized coal (material to be cleaned). A filtering aeration nozzle 151 for jetting air supplied from the filtering aeration blower 150 is disposed at the bottom of the membrane treatment tank 120.
The porous membrane 130 is disposed above the aeration nozzle 151 for filtration in the membrane treatment tank 120, and is configured to filter the washing water and remove the pulverized coal for purification. A filter line 160 for sucking up the filtered washing water is connected to the upper end of the porous membrane 130, and a filter pump 161 is provided in the filter line 160. The pulverized coal (material to be cleaned) separated in the membrane treatment tank 120 is extracted from the bottom of the membrane treatment tank 120 by a sludge separation pump 170 and is recovered and treated.
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 water permeation amount of the porous membrane 130 is equal to or less than a set value. A regeneration aeration nozzle 181 for spraying air supplied from a regeneration aeration blower 180 is disposed at the bottom of the chemical cleaning tank 140.
The film processing unit 100 includes: a backwashing unit 190 for backwashing the porous membrane 130 with water; and a surface cleaning unit 200 that cleans the surface of the porous membrane 130 backwashed by the backwashing unit 190. The backwashing unit 190 includes: a backwash line 191 connected to the midway of the filter line 160; a backwash pump 192 connected to the backwash line 191 and supplying backwash water; a backwash valve 193 provided midway in the backwash line 191; and a controller 195 that periodically outputs an open signal 194 to the backwash valve 193. The backwashing unit 190 may be configured such that the backwashing pump 192 is replaced with a blower and air is used for backwashing instead of water.
The membrane treatment unit 100 includes a settling tank 110, and the settling tank 110 is provided upstream of the membrane treatment tank 120, and guides the washing water of the upper surface clarification portion in which the pulverized coal is settled to the membrane treatment tank 120. A baffle 111 is provided in the settling tank 110, and the baffle 111 prevents the washing water from being discharged to the membrane treatment tank 120 by short-cut before the pulverized coal is settled. The pulverized coal (material to be cleaned) settled in the settling tank 110 is extracted from the bottom of the settling tank 110 by a sludge settling pump 210 and recovered.
Further, as the porous membrane 130, a filter obtained by stretching Polytetrafluoroethylene (PTFE) is used.
In addition, as the chemical, in the case where the porous membrane 130 is a filter obtained by stretching polytetrafluoroethylene, sodium hydroxide (NaOH) can be used. The concentration of the aqueous solution of sodium hydroxide can be set to 1% to 10%.
In one example of the water treatment apparatus of the present invention, the apparatus is a conveyor C for coal handling equipment as shown in fig. 5, and the material to be cleaned is pulverized coal, but the conveyor C is provided with a plurality of conveyors, and the membrane treatment unit 100 is dispersedly provided for each of the conveyors C. The cleaning water purified by the membrane processing unit 100 and pressurized by the water jet pump 220 is jetted from a water jet nozzle (not shown) to clean the conveyor C.
Next, the operation of an example of the water treatment method and apparatus will be described.
First, as shown in fig. 5, the conveyor C, which is an equipment for coal transportation, is washed by spraying water from a water spray nozzle (not shown) with washing water pressurized by a water spray pump 220. At this time, washing water containing pulverized coal as a substance to be washed is collected (see "collection step" of step S10 in fig. 3).
The washing water recovered by the recovery process is sent to the membrane process unit 100. In the membrane process unit 100, first, the fine coal contained in the washing water is sedimented in the sedimentation tank 110 (see "sedimentation step" in step S20 in fig. 3). Here, since the baffle 111 is provided inside the settling tank 110, the washing water is prevented from being discharged to the membrane treatment tank 120 by short circuiting before the pulverized coal is settled. The pulverized coal (material to be cleaned) settled in the settling tank 110 is extracted from the bottom of the settling tank 110 by a sludge settling pump 210 and recovered. The washing water of the upper clarified part after the sedimentation of the pulverized coal is guided to the membrane treatment tank 120.
The washing water of the upper clarified portion after settling the fine coal included in the washing water in the settling tank 110 as the above-described settling step is guided to the membrane treatment tank 120. In the membrane treatment tank 120, the air pressurized by the filter aeration blower 150 is ejected from the filter aeration nozzle 151, and the washing water is filtered by the porous membrane 130 disposed above the filter aeration nozzle 151 to remove the fine coal and purify the water (see "membrane filtration step" in step S30 in fig. 3). The washing water filtered by the aforementioned porous membrane 130 is sucked upward from the filter line 160 by the filter pump 161. The pulverized coal (material to be cleaned) separated in the membrane treatment tank 120 is extracted from the bottom of the membrane treatment tank 120 by a sludge separation pump 170 and is recovered and treated.
The washing water filtered and purified by the membrane treatment tank 120 as the membrane filtration step is pressurized by the water spray pump 220 shown in fig. 5, and is sprayed from the water spray nozzles (not shown) to wash the conveyor C (see the "reuse step" of step S90 in fig. 3).
While the recovery step, the sedimentation step, the membrane filtration step, and the reuse step are performed, the time is counted by a timer, and it is determined whether or not 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 is backwashed with water supplied from the backwashing pump 192 through the backwashing line 191 and the filter line 160 (see "backwashing step" in step S50 of fig. 3). In the backwashing, the filter pump 161 is stopped. The surface of the backwashed porous membrane 130 is cleaned by the surface cleaning unit 200 (see "surface cleaning step" of step S60 in fig. 3). This eliminates clogging of the porous membrane 130. After the backwashing is completed, the backwashing valve 193 is closed.
However, with continued operation, clogging of the porous membrane 130, which cannot be completely removed by backwashing alone, also occurs. Then, it is determined whether or not the water permeation amount of the porous membrane 130 is equal to or less than a set value (see step S70 in fig. 3). When the water permeation amount of 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 washing tank 140. An aqueous solution of sodium hydroxide is stored in the chemical cleaning tank 140, and air pressurized by the regeneration aeration blower 180 is ejected from the regeneration aeration nozzle 181. The porous membrane 130 is immersed in an aqueous solution of sodium hydroxide and aerated to regenerate the porous membrane 130 (see "regeneration step" of step S80 in fig. 3).
Here, if cellulose acetate, polyethylene, polypropylene, polysulfone, polyethersulfone, polyamide, polyvinyl alcohol, polyvinylidene fluoride, or the like is used as the porous membrane 130, it cannot be said that the durability and chemical resistance are sufficient, and therefore if sodium hydroxide is used as the chemical, it becomes difficult to continue the operation of filtering the washing water and removing the pulverized coal to purify the same.
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 stretching polytetrafluoroethylene, the durability and chemical resistance are excellent, and even when special effluent water such as washing water containing pulverized coal is targeted, the reduction in the flow rate of the washing water passing through the porous membrane 130 can be prevented, and the porous membrane 130 can be regenerated without being blocked irreversibly, and the porous membrane 130 can be regenerated without stopping the operation and the porous membrane 130 can be regenerated smoothly.
Thus, the operation of filtering the washing water by the membrane treatment can be continued stably.
In one example of the water treatment method of the present invention, the regeneration step is preceded by a backwashing step of periodically backwashing the porous membrane 130 and a surface cleaning step of cleaning the surface of the porous membrane 130 backwashed by the backwashing step. In addition, 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 surface cleaning unit 200 cleaning the surface of the porous membrane 130 backwashed by the backwashing unit 190. With such a configuration, the time required for regeneration of the porous membrane 130 with a chemical can be prolonged and the porous membrane is effective.
In one example of the water treatment method of the present invention, there is a sedimentation step: after the substances to be cleaned contained in the cleaning water recovered in the recovery step are settled, the cleaning water in the upper clear part is guided to the membrane filtration step. In one example of the water treatment apparatus of the present invention, the membrane process unit 100 includes a settling tank 110 which is provided upstream of the membrane process tank 120 and guides the washing water of the upper surface clarification portion in which the substance to be washed is settled to the membrane process tank 120. With such a configuration, pulverized coal which is called amorphous carbon (amorphous carbon) and performs a special operation can be separated and removed in advance before being filtered by the membrane process unit 100, and the separation efficiency at the membrane process unit 100 can be improved.
In one 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, the membrane processing unit 100 having excellent durability and chemical resistance and capable of favorably performing a regeneration process can be provided.
In one example of the water treatment method and apparatus of the present invention, the aforementioned chemical agent is sodium hydroxide. With such a configuration, the porous membrane 130 formed of the filter obtained by stretching polytetrafluoroethylene can be efficiently regenerated.
In one example of the water treatment apparatus of the present invention, the aforementioned apparatus is a conveyor C of a coal handling facility, and the aforementioned substance to be cleaned is pulverized coal. With such a configuration, unlike coagulation and sedimentation by a coagulant used for treatment of washing water in the conventional conveyor C, no remaining of fine coal into the washing water due to a shortage of the amount of the coagulant added occurs, and clogging of nozzles for spraying washing water and abrasion of pipes do not occur. Of course, the flocculant does not remain in the reused cleaning water due to an excessive amount of the flocculant, and there is no concern about the flocculation of the flocculant in the piping or the clogging of the piping. Further, since the pulverized coal is not aggregated and concentrated, the aggregate of the flocs of the metal oxide and the pulverized coal derived from the aggregating agent is not generated, and the increase in the disposal cost is avoided.
In one example of the water treatment apparatus of the present invention, the plurality of conveyors C are provided, and the membrane treatment units 100 are dispersedly provided for each of the conveyors C. With such a configuration, the overall operation efficiency can be improved and the cost can be reduced, compared to the case where the cleaning water collected from the plurality of conveyors C is collectively treated by the coagulation treatment unit 50 as in the conventional example shown in fig. 1.
Example 1
Hereinafter, examples of the water treatment method and apparatus of the present invention will be described.
First, when the porous membrane 130 was washed with a chemical for regeneration, the conveyor C (instrument) was washed in parallel with a porous membrane made of Polytetrafluoroethylene (PTFE) (Poreflon (registered trademark): sumitomo electric) and a porous membrane made of polyvinylidene fluoride (PVDF) (sterrapore (registered trademark): mitsubishi chemical), washing water (discharge raw water: analysis value reference [ table 1]) containing pulverized coal (substance to be washed) was subjected to a liquid-passing treatment, converted values for the same membrane areas were compared, and changes in the differential pressures with the passage of time were observed, and the results shown in [ table 2] were obtained.
[ Table 1] < analysis values of discharged raw Water >
[ Table 2] < results of parallel liquid passing between PTFE film and PVDF film >
In the above [ table 2], as initial setting conditions, the permeation flux was:
1.5[m3/(m2･ days) =62.5[ L/h]The set value of the point at which the differential pressure (suction pressure) is reached is 40 kPa]。
The following two were provided separately to the regeneration test by the agent wash: in the case of a porous membrane made of Polytetrafluoroethylene (PTFE), the calculated value of the actual permeation flux decreased to 72[% ] after 120 hours had elapsed; the calculated value of the actual permeation flux of the porous membrane made of polyvinylidene fluoride (PVDF) was decreased to 68[% ] after 96 hours.
Before the regeneration test, the porous membrane was backwashed with tap water.
As conditions for backwashing with the tap water, flux was set as follows:
3[m3/(m2･ days) =125[ L/h]The time was set to 5 minutes.
The results are shown in Table 3.
[ Table 3] < results of backwashing with tap Water >
After the backwashing with the tap water, the porous membrane made of Polytetrafluoroethylene (PTFE) and the porous membrane made of polyvinylidene fluoride (PVDF) are cleaned with chemicals (citric acid, sodium hypochlorite, sodium hydroxide) and regenerated.
The citric acid washing was performed in the following order.
1. After backwashing with tap water, the water tank is filled with 0.5[% ] citric acid solution, so that the aeration blower for filtration continues to operate.
2. The impregnation treatment was carried out for 8 hours or more.
3. The citric acid solution is discarded, and the conveyor C (equipment) is cleaned and replaced with cleaning water (discharge raw water) containing pulverized coal (material to be cleaned), and the pH is set to 6 or more.
4. The solution was passed through the filter under constant filtration conditions.
Sodium hypochlorite cleaning was performed in the following order.
1. After backwashing with tap water, the water tank is filled with 0.05[% ] sodium hypochlorite solution, and the aeration blower for filtration continues to operate.
2. The impregnation treatment was carried out for 8 hours or more.
3. The pH of the sodium hypochlorite solution is set to 8 or less while the sodium hypochlorite solution is discarded and the conveyor C (equipment) is cleaned and replaced with cleaning water (discharge raw water) containing pulverized coal (substance to be cleaned).
4. The solution was passed through the filter under constant filtration conditions.
The sodium hydroxide washing was performed in the following order.
1. After back washing with tap water, the water tank is filled with 10[% ] sodium hydroxide solution, and the aeration blower for filtration continues to operate.
2. The impregnation treatment was carried out for 8 hours or more.
3. The pH of the waste sodium hydroxide solution is set to 8 or less while cleaning the conveyor C (equipment) and replacing it with cleaning water (discharge raw water) containing pulverized coal (material to be cleaned).
4. The solution was passed through the filter under constant filtration conditions.
The regeneration results by the above-described chemical washing are shown in [ table 4 ].
[ Table 4] < regeneration results by chemical washing >
The proportion of recovery for the initial permeate flux 62.5[ L/h ] was determined from the following equation:
100 × {1- (permeate flux after washing)/(initial permeate flux) } [% ].
Incidentally, as for the porous film made of polyvinylidene fluoride (PVDF), the film surface thereof is thin and dark brown. That is, it was judged that a porous film made of polyvinylidene fluoride (PVDF) tends to be intolerant to sodium hydroxide.
As a result of the present example, it can be said that the porous membrane made of Polytetrafluoroethylene (PTFE) is regenerated by washing with sodium hydroxide as a chemical.
The water treatment method and apparatus of the present invention are not limited to the above-described examples and embodiments, and can be applied to cleaning of conveyors in coal-carrying facilities of coal-fired power stations, and other applications.
Description of the symbols
100 film processing unit
110 settling tank
120 film treatment tank
130 porous membrane
140 medicament cleaning tank
190 backwash unit
200 surface cleaning unit
C conveyor (apparatus).
Claims (13)
1. A water treatment method comprising:
a recovery step of cleaning the instrument and recovering cleaning water containing the substance to be cleaned;
a membrane filtration step of filtering the washing water recovered in the recovery step with a porous membrane to remove and purify the substance to be washed;
a reuse step of reusing the cleaning water purified in the membrane filtration step; and
and a regeneration step of cleaning the porous membrane with a chemical when the water permeation amount of the porous membrane from which the substance to be cleaned has been removed in the membrane filtration step is equal to or less than a set value.
2. The water treatment method according to claim 1, comprising, as a previous stage of the regeneration step:
a backwashing step of periodically backwashing the porous membrane; and
and a surface cleaning step of cleaning the surface of the porous membrane backwashed in the backwashing step.
3. The water treatment method according to claim 1 or 2, comprising a sedimentation step of: after the substances to be cleaned included in the cleaning water recovered in the recovery step are settled, the cleaning water in the upper clarified part is guided to the membrane filtration step.
4. The water treatment method according to any one of claims 1 to 3, wherein the porous membrane is a filter obtained by stretching polytetrafluoroethylene.
5. The water treatment method according to claim 4, wherein the chemical is sodium hydroxide.
6. The water treatment method according to any one of claims 1 to 5, wherein the apparatus is a conveyor of a coal handling facility, and the substance to be cleaned is pulverized coal.
7. A water treatment device provided with a membrane treatment unit having:
a membrane processing tank into which cleaning water containing a substance to be cleaned is introduced;
a porous membrane disposed inside the membrane treatment tank, for filtering the washing water to remove and purify a substance to be washed; and
and a chemical cleaning tank for cleaning the porous membrane with a chemical when the water permeation amount of the porous membrane is equal to or less than a set value.
8. The water treatment apparatus according to claim 7, wherein the membrane treatment unit comprises:
a backwashing unit that backwashes the porous membrane; and
and a surface cleaning unit which cleans the surface of the porous membrane backwashed by the backwashing unit.
9. The water treatment apparatus according to claim 7 or 8, wherein the membrane treatment unit includes a settling tank which is provided upstream of the membrane treatment tank and guides the washing water of the upper surface clarification portion after the substance to be washed is settled to the membrane treatment tank.
10. The water treatment apparatus according to any one of claims 7 to 9, wherein the porous membrane is a filter obtained by stretching polytetrafluoroethylene.
11. The water treatment apparatus of claim 10, wherein the agent is sodium hydroxide.
12. A water treatment device according to any one of claims 7 to 11, wherein the apparatus is a conveyor of a coal handling facility and the material to be cleaned is coal dust.
13. The water treatment apparatus according to claim 12, wherein a plurality of the conveyors are provided, and the membrane treatment unit is dispersedly provided for each of the conveyors.
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| JP2017-222547 | 2017-11-20 | ||
| JP2017222547A JP6811162B2 (en) | 2017-11-20 | 2017-11-20 | Water treatment method and equipment |
| PCT/JP2018/027986 WO2019097767A1 (en) | 2017-11-20 | 2018-07-25 | Method and device for water treatment |
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| CN111417597A true CN111417597A (en) | 2020-07-14 |
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| JP (1) | JP6811162B2 (en) |
| CN (1) | CN111417597A (en) |
| WO (1) | WO2019097767A1 (en) |
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| CN1334251A (en) * | 2001-08-31 | 2002-02-06 | 上海乐富门水处理工程有限公司 | Process for treating waste water with coal ash |
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| CN103249472A (en) * | 2010-12-10 | 2013-08-14 | 东丽株式会社 | Chemical cleaning method for immersed membrane element |
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| CN106794428A (en) * | 2014-08-29 | 2017-05-31 | 三菱电机株式会社 | The cleaning method and cleaning device and water treatment system of filter membrane |
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| JP3871749B2 (en) * | 1996-11-18 | 2007-01-24 | 東北電力株式会社 | Treatment method of flue gas desulfurization waste water |
| JP2004267892A (en) * | 2003-03-07 | 2004-09-30 | Toshiba Corp | Wastewater treatment equipment |
| JP2006043655A (en) * | 2004-08-09 | 2006-02-16 | Japan Organo Co Ltd | Water treating apparatus and operation method therefor |
| JP2009233569A (en) * | 2008-03-27 | 2009-10-15 | Kurita Water Ind Ltd | Membrane separation method |
| JP2011115712A (en) * | 2009-12-02 | 2011-06-16 | Mitsubishi Heavy Ind Ltd | Washing method of filter membrane |
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- 2017-11-20 JP JP2017222547A patent/JP6811162B2/en active Active
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- 2018-07-25 CN CN201880075085.6A patent/CN111417597A/en active Pending
- 2018-07-25 WO PCT/JP2018/027986 patent/WO2019097767A1/en active Application Filing
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1334251A (en) * | 2001-08-31 | 2002-02-06 | 上海乐富门水处理工程有限公司 | Process for treating waste water with coal ash |
| CN101525191A (en) * | 2009-04-27 | 2009-09-09 | 河南洁源膜分离科技有限公司 | Coking wastewater membrane method treating process |
| CN103249472A (en) * | 2010-12-10 | 2013-08-14 | 东丽株式会社 | Chemical cleaning method for immersed membrane element |
| CN106794428A (en) * | 2014-08-29 | 2017-05-31 | 三菱电机株式会社 | The cleaning method and cleaning device and water treatment system of filter membrane |
| CN204474371U (en) * | 2014-12-23 | 2015-07-15 | 三达膜科技（厦门）有限公司 | A kind for the treatment of unit of coal washing waste water |
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| JP6811162B2 (en) | 2021-01-13 |
| JP2019093320A (en) | 2019-06-20 |
| WO2019097767A1 (en) | 2019-05-23 |
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