KR101853095B1 - Method for Removing Algae in Water - Google Patents

Abstract

The present invention relates to a method of removing algae using fine bubbles and electrical coagulation, more particularly, to a method of removing algae containing influent, comprising the steps of transferring algae-containing influent water, removing solid matter from the influent water, Generating fine bubbles by mixing the inflow water containing the fine bubbles and the algae with a flocculant using a fine bubble mixing device; treating the treated water electrically with the first treatment module to cause flocculation and flocculation; The method comprising the steps of separating the algae-containing suspended matter and the treated water, further removing the algae-containing suspended matter in the second treatment module, and transferring the final treated water to the filter paper, ≪ / RTI >
According to the present invention, algae can be flocculated and floated at a higher speed than existing algae removing devices, so that algae can be quickly removed and the processing time can be saved, which is effective in removing large-sized algae. When introducing the method of the present invention into an additional step, the algae can be removed more quickly than the conventional method, and it is possible to effectively cope with the occurrence of a lot of green tide in the inflow water.

Description

Method for Removing Algae in Water

The present invention relates to a method of removing algae using fine bubbles and electrical coagulation, more particularly, to a method of removing algae containing influent, comprising the steps of transferring algae-containing influent water, removing solid matter from the influent water, Generating fine bubbles by mixing the inflow water containing the fine bubbles and the algae with a flocculant using a fine bubble mixing device; treating the treated water electrically with the first treatment module to cause flocculation and flocculation; The method comprising the steps of separating the algae-containing suspended matter and the treated water, further removing the algae-containing suspended matter in the second treatment module, and transferring the final treated water to the filter paper, ≪ / RTI >

Water is an indispensable resource for all human economic, social and cultural activities. However, due to population increase, rapid increase of water consumption due to industrialization, and water pollution caused by environmental pollution, the water shortage situation is getting worse each year.

In the summer when the water temperature rises, reservoirs, lakes, fisheries, offshore waters or running water are also producing green tides or red tides. These algae or red tides will kill not only the fish in the lake or sea farm but also the aquatic plants, which can cause ecological destruction as well as bad smell.

In general, algae phenomenon is caused by eutrophicated lakes or floodplains (phytoplankton) in a slow stream, which are accumulated on the surface of water and change the color of the water remarkably to green. It is known that the cause of the algae phenomenon is adversely affecting aquatic plants by the toxic cyanobacteria. For example, it causes serious problems such as the effects of toxins on human body and livestock, ecological problems caused by ecosystem destruction, fish deficiency due to oxygen deficiency and various kinds of aquatic organisms.

In addition, the red tide phenomenon refers to the phenomenon that the color of the seawater changes in red color due to the proliferation of a large amount of phytoplankton. When the creature causing red tide is caused by the ciliate or diatoms classified as euglena or protozoa The red tide phenomenon has recently been shown widely in the southern coast of Korea, the west sea, and the southern coast of the East Sea, and the red tide creatures are moving from the center of the diatoms to the center of the flagellated tide, Due to this trend, red tide damage is increasing every year.

In recent years, such rust and red tide phenomenon has occurred as a characteristic of wide area, toxicity, and prolongation, and development of technology for solving this is urgently required.

Conventional techniques for solving such phenomenon include a method of adsorbing a green or red tide with electrostatic adsorption power by using a chemical sterilizing method using a chlorine agent or ozone, A filtration method in which a green and a red tide are separated and removed from water, a method of removing algae using microorganisms, an ultrasonic wave, and a tidal line are generally used.

Chemical sterilization methods using chlorine drugs or ozone are considered harmful to humans when used in drinking water sources and agricultural water, and are difficult to use because they are harmful to crops, and recreational activities such as swimming pools are also affected. In addition, chemical agents may adversely affect the natural ecological environment and cause water quality to deteriorate further.

The coagulation sedimentation method using loess is a method in which algae or red algae are removed by adsorbing and aggregating suspended substances (nutrients, fine plankton, etc.) in the water through colloid particles of yellow clay (KR10-1355178). However, when this method is used, some green algae and red algae are removed by mass spraying, but more dissolved oxygen is needed to decompose the rusty red algae that have flocculated under the water due to the yellowing, As the flow of oxygen through the water causes oxygen shortage, eutrophication is accelerated, and ultimately, aquatic plants or microorganisms that require oxygen may cause a dead lake or sea that no longer lives.

The filtration method of the green algae and the red algae using the filter is a physical method of separating the water, the green algae and the red algae by passing the water contaminated by the green algae through the filtration device including the filter and consuming excessive energy It is difficult to use it in a general manner.

In addition, the method of removing algae using microorganisms has the possibility that the introduced microorganism species may destroy or contaminate another ecological environment in order to remove the algae or red tide problem to be removed. In addition, A chemical treatment process for removing residual microorganisms is necessary, and the scale and operation cost are expected to increase.

The ultrasound method has the advantage of removing green algae in an environmentally friendly manner by destroying the air bag of the algae while sinking the algae below the water. On the other hand, it is difficult to use the algae in a large area, have.

The green tide removal line method has a drawback in that it requires a greenhouse suction and a filtration and collection device to operate the vessel, which removes green tide, but requires a high maintenance cost.

Recently, microbubble technology is emerging as a new alternative technology in the field of algae removal. The related patents use microbubbles to maintain the water temperature at a low temperature and to supply oxygen to the lower layer of the water while reducing greenhouse (KR10-1196945). However, this patent is used with the ground water and micro bubble algae prevention and but reduce the water purification, micro in the bubble generation method has a problem in durability of the size and occurrence of bubbles, is simply the oxygen use of microbubbles (O ₂ (DO). However, there is no solution to the problem of clogging of nozzles due to suspended or suspended substances in contaminated water, and in particular, It is difficult to perform the function of purifying the water in the lower part of the water.

In order to compensate for the disadvantages described above, the purification treatment unit of the water curing treatment type which increases the dissolved oxygen (DO) while maintaining the water surface temperature of the water within a certain water level by using the heat exchange of the geothermal heat and the nano bubble KR10-1361104). However, since the nano bubble supplying unit and the equipment are buried in the ground, the above-mentioned patent has a high initial facility construction cost and is not easy to move after installation of the equipment.

In addition, a new technique for removing green algae is the algae removing device using the potential difference method (KR10-0993009). When an inorganic salt that provides a positive charge and a magnetic powder modified with a polymer are injected into a wastewater or wastewater and shaken, the greenhouse and the suspended material that are negatively charged are magnetized by a potential difference method, Phosphate adsorbed on the surface of the powder and present in an ionic state in the water reacts with the inorganic salt to form an insoluble phosphate which is a suspended substance and is supplied with magnetic force through a permanent magnet or an electromagnet, It is a method to remove substances and phosphates at high speed. However, this method has to supply continuous magnetic powder, and there is a possibility of contamination of water due to the magnetic powder which may exist after the treatment, and there is a troublesome operation in the water to be treated in the reactor.

The water treatment process is usually performed by removing sediments from the water taken from the water intake tower such as sand and mud that are contained in raw water, coagulant added from the chemical input facility, mixed soil mixed with debris such as suspended substances, The sedimentation basin is a sedimentation basin that sinks heavy sediments that are made by agglomeration of sediments such as heavy aggregates that weigh heavily by putting chemicals into heaps, It is composed of a filter paper to filter the filtered paper and treated water that passes through the filter paper, a reservoir to remove microorganisms by contacting a trace amount of chlorine, and a drain pump to pump the treated water collected from the reservoir to each customer.

However, in the case where a large amount of algae is generated in the inflow water, there is a limitation in algae removal only in the above process, and there is a need to improve such a problem. In relation to this, in many domestic water treatment plants, And is trying to improve the smell.

As a result, the inventors of the present invention have made efforts to develop a method capable of additionally installing in existing water purification facilities and removing algae present in water at a high speed. As a result, they have focused on a method using microbubbles and electrical coagulation, It was confirmed that the algae could be removed at high speed, and the present invention was completed.

It is an object of the present invention to provide a method of removing algae using fine bubbles and electrical coagulation.

In order to accomplish the above object, the present invention provides a method of manufacturing a water treatment system, comprising the steps of: (a) transferring algae-containing influent water using a transfer device 88; (b) removing the solids from the influent using the treatment device 87; (c) generating fine bubbles in the algae-containing influent water from which the solids are removed by using the fine bubble generator 81; (d) mixing the inflow water containing fine bubbles and algae with a flocculant using a fine bubble mixing device 82, and performing a primary treatment; (e) electrically treating the primary treatment water in the first treatment module (84) to induce flocculation and floating, and separating the algae-containing suspended matter and treatment water; (f) holding the treated water separated in step (e) in the second treatment module (85) to further remove the algae-containing float; And (g) transferring the treated water from which the algae have been further removed in the step (f) to the gypsum, wherein the treatment device (87) comprises a cyclone, a hydrocyclone, a multi- And the fine bubble mixing device (82) has one or more selected from the group consisting of a generator and a line staple mixer, and the first processing module (84) (I) an upper reaction tank 110 in which substances of the introduced fluid are suspended and separated; (Ii) an inflow path (105) connected to an intermediate portion of the upper reaction tank (110) and through which the fluid flows; (Iii) an upper cap 103 coupled with an upper portion of the upper reaction vessel 110; (Iv) a first discharge path (104) connected through the lower end surface of the upper cap (103); (V) a lower reactor 111 connected to the lower end of the upper reactor 110; (Vi) a catalyst module (108) installed in the lower reaction tank (111); (Iii) a second discharge path 107 coupled through an intermediate surface of the lower reaction tank 111; And a lower cap (112) coupled to a lower end of the lower reaction tank (111). The second processing module (85) is characterized in that (a) An upper reaction tank 110; (B) an inflow path (105) connected to an intermediate portion of the upper reaction tank (110) and through which fluid flows; (C) an upper cap (103) coupled with an upper portion of the upper reaction tank (110); (D) a first discharge path (104) connected through the lower end surface of the upper cap (103); (E) a lower reaction tank 111 connected to a lower end portion of the upper reaction tank 110; (F) a second discharge path 107 coupled through an intermediate surface of the lower reaction tank 111; And (c) a lower cap (112) coupled to a lower end of the lower reaction tank (111).

According to the present invention, algae can be flocculated and floated at a higher speed than existing algae removing devices, so that algae can be quickly removed and the processing time can be saved, which is effective in removing large-sized algae. When introducing the method of the present invention into an additional step, the algae can be removed more quickly than the conventional method, and it is possible to effectively cope with the occurrence of a lot of green tide in the inflow water.

Fig. 1 is a configuration diagram of an apparatus used for the algae elimination method.
FIG. 2 is a view showing the purification process when the algae elimination method is additionally installed in a water treatment plant.
3 is a diagram showing the configurations of the first processing module and the second processing module.
4 is a view showing a configuration of a catalyst module.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

In one aspect, the present invention provides a method comprising: (a) transferring algae-containing influent using a transfer device 88; (b) removing the solids from the influent using the treatment device 87; (c) generating fine bubbles in the algae-containing influent water from which the solids are removed by using the fine bubble generator 81; (d) mixing the inflow water containing fine bubbles and algae with a flocculant using a fine bubble mixing device 82, and performing a primary treatment; (e) electrically treating the primary treatment water in the first treatment module (84) to induce flocculation and floating, and separating the algae-containing suspended matter and treatment water; (f) holding the treated water separated in step (e) in the second treatment module (85) to further remove the algae-containing float; And (g) transferring the treated water from which the algae have been further removed in the step (f) to the gypsum, wherein the treatment device (87) comprises a cyclone, a hydrocyclone, a multi- And the fine bubble mixing device 82 has one or more members selected from the group consisting of a generator and a line stitch mixer, and the first processing module 84 ) Comprises: (i) an upper reaction tank 110 in which substances of the introduced fluid float and are separated; (Ii) an inflow path (105) connected to an intermediate portion of the upper reaction tank (110) and through which the fluid flows; (Iii) an upper cap 103 coupled with an upper portion of the upper reaction vessel 110; (Iv) a first discharge path (104) connected through the lower end surface of the upper cap (103); (V) a lower reactor 111 connected to the lower end of the upper reactor 110; (Vi) a catalyst module (108) installed in the lower reaction tank (111); (Iii) a second discharge path 107 coupled through an intermediate surface of the lower reaction tank 111; And a lower cap (112) coupled to a lower end of the lower reaction tank (111). The second processing module (85) is characterized in that (a) An upper reaction tank 110; (B) an inflow path (105) connected to an intermediate portion of the upper reaction tank (110) and through which fluid flows; (C) an upper cap (103) coupled with an upper portion of the upper reaction tank (110); (D) a first discharge path (104) connected through the lower end surface of the upper cap (103); (E) a lower reaction tank 111 connected to a lower end portion of the upper reaction tank 110; (F) a second discharge path 107 coupled through an intermediate surface of the lower reaction tank 111; And (c) a lower cap 112 coupled to a lower end of the lower reaction tank 111 (FIGS. 1 and 3).

In the present invention, the step (a) may be a step of transferring the inflow water to the gypsum via the bypass 89 using the transfer device 88 when algae removal is unnecessary.

The method may further include separating water and sludge using the dewatering device 86 from the suspended solids separated in steps (e) and (f), and the dewatering device 86 may be used as a filter press .

The step (f) may further include an electrically treating step.

The transfer device 88 may be used as a transfer means or pump using gravity or pressure.

The second processing module 85 may further include a catalyst module 108 installed in the lower reaction tank 111.

In the present invention, the ratio of the fluid flowing into the fine bubble mixing device 82 to the flocculant may range from 10: 1 to 5000: 1, and the flocculant may be selected from the group consisting of polyaluminum chloride (PAC) Aluminum chloride, aluminum sulfate, aluminum sulfate, aluminum chloride, aluminum chloride and inorganic salts of ferric chloride, preferably polyaluminum chloride.

The coagulant may be used in a mixture of 5 ppm to 50 ppm of the undiluted solution.

If the coagulant is used at a concentration of 5 ppm or less relative to the undiluted solution, aggregation of the algae may not be performed well. If the concentration of the coagulant is 50 ppm or more, the flocculation effect may not be excellent and the operation cost may be increased. The flocculant mixed with one or more selected ones of the flocculants forms a variety of monomeric species through the hydrolysis reaction in the treatment module, and the thus formed metal hydroxide coagulates with the algae.

Further, in order to increase the electric conductivity, the flocculant may be added to one or more salt compounds selected from the group consisting of calcium chloride, sodium chloride, magnesium chloride and iron chloride so that the concentration of the salt compound to the flocculant is 0.1 wt% to 5.0 wt% And the like. This is because if the concentration of the salt compound to the flocculant is less than 0.1 wt%, the flocculation reaction may not occur well because the electric power is not supplied to the treated water. If the concentration is 5.0 wt% or more, The above-mentioned excellent effect can not be expected, and the operating cost against the production efficiency can be increased.

In the present invention, the first processing module 84 and the second processing module 85 include a union 106 coupled to a lower portion of the upper reaction tank 110 and an upper portion of the lower reaction tank 111, And a drain 109 for internal cleaning connected to the lower end surface of the cap 112. The inside of the upper reaction tank 110 and the lower reaction tank 111 are connected to each other and the outside is connected to a union 106, respectively.

In the present invention, 1 to 20,000 of the first processing module 84 and the second processing module 85 may be connected in series or in parallel, but are not limited thereto. Depending on the volume of water to be treated, more than 20,000 can be used.

Further, the first processing module 84 and the second processing module 85 may be configured such that 1 to 20,000 pairs of processing modules are connected in series or in parallel. However, the present invention is not limited thereto. More than 20,000 pairs can be used depending on the volume of water to be treated.

The means 83 for supplying the flocculant to the microbubble mixing device 82 may further comprise means 83 for supplying the flocculant to the microbubble mixing device 82, It can be used as conveying means or pump using pressure.

In the present invention, the catalyst module 108 includes (i) a catalyst plate 71 to which electrons are supplied; (ii) a separation guide (72) for fixing the catalyst plate (71) and supplying electricity; (iii) a separation plate 74 for supplying power to the separation guide 72 and detachably attached thereto; (iv) a first contact terminal 75 connected to the separation guide 72 to supply electricity to the catalyst plate 71; And (v) a second contact terminal 73 connected to the separation plate 74 to supply electricity to the separation guide 72 (FIG. 4).

The catalytic plate of the catalytic module 108 may be made of platinum (Pt) and may have a thickness of 0.5 mm to 2.0 mm. When the thickness is 0.5 mm or less, the electrode may be damaged by a rapid flow of fluid or the like, and the electrode may be manufactured in the range of 0.5 mm to 2 mm depending on the process conditions. If applied at more than 2 mm, operating costs may be higher compared to process efficiency. When the catalyst plate is used as platinum (Pt), there is no damage due to oxidation or reduction of the electrode, and aluminum ions can be supplied through the coagulant, so that the continuously cultivated algae can be recovered without replacing the electrodes. It is not limited.

The voltage supplied to the fluid through the catalyst module 108 may be between 2V and 50V and the current may be between 0.1A and 10.0A. When supplying voltage and current lower than this range, algae and coagulant may not coagulate well. If voltage and current higher than this range are supplied, algae and flocculant may get rid of around the electrode. A problem may arise.

The inflow water from which the solids are removed through the steps (a) and (b) is introduced into the micro bubble generator 81, microbubbles are generated in the inflow water, and the process water, 31 to flow into the fine bubble mixing device 82. After mixing with the flocculant in the fine bubble mixing device 82, the treated water mixed with the flocculant through the above process flows into the first treatment module 84, is electrically treated in the first treatment module 84, Causing floating, and microbubble-containing floats float to the upper layer. The treated water in the first treatment module 84 is discharged through the second discharge passage 107 connected to the lower reaction tank 111 and transferred to the second treatment module 85. The transferred processed water is retained in the second treatment module 85 to remove the suspended matter, and the final treated water is transferred to the filter paper, and the suspended matter separated from the first treatment module and the second treatment module is returned to the dehydration device 86 And separated into sludge and water through the dewatering device.

When the algae removal method is additionally installed in the water purification plant, the influent water is supplied through the water intake pump in the algae removal method, and the water treated by the method of the present invention is transferred to the gypsum (FIG. 3).

In one embodiment of the present invention, an algae elimination experiment using the algae elimination method of the present invention was carried out at the water source sewage treatment plant effluent where algae contamination is proceeding. BOD, COD and SS values of treated water were 12.0, 13.8 and 13.2 mg / L, respectively, in this experiment. In this experiment, four treatment modules were connected in parallel to promote flocculation and flocculation. As a result of water quality analysis of effluents treated by the apparatus and method of the present invention, it was confirmed that the values of BOD, COD and SS were 5.0, 1.8 and 2.7 mg / L, respectively. In this experiment, it was confirmed that the residence time (RT) of the influent water treatment module was about 22 seconds. Through this, it was confirmed that rapid algae removal occurred through the present invention and the apparatus.

Hereinafter, the present invention will be described in more detail with reference to Examples. It will be apparent to those skilled in the art that these embodiments are merely illustrative of the present invention and that the scope of the present invention is not limited to these embodiments.

Example  : Experiment to remove underwater algae using algae removing device

In this embodiment, effluent from a water source sewage treatment plant was used as algae-containing wastewater, and e-PAC was diluted to 25 ppm as a coagulant. In the fine bubble mixing device 30L, the coagulant and the raw water were stirred at 800 rpm, and the voltage and the current were supplied at 30 V and 5 A, respectively, and the residence time of the raw water was about 5 seconds. Experiments were also conducted using four treatment modules (50L × 2, 12.5L × 2). Voltage and current were supplied to each processing module at 30V, 5A (50L), 8V, 5A (12.5L), and the residence time of raw water was about 22 seconds. Before and after the experiment, samples of effluent water before treatment and samples of treated water by algae removal method were collected and the following analysis results were confirmed.

As a result, the BOD, COD and SS values of the treated water were 12.0, 13.8 and 13.2 mg / L, respectively. However, as a result of the water quality analysis of the effluent treated by the apparatus and method of the present invention, Were found to be 5.0, 1.8 and 2.7 mg / L, respectively. It was also confirmed that the total E. coli values were significantly lowered.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. The actual scope of the invention is therefore defined by the appended claims and their equivalents.

71: catalyst plate 72: separation guide
73: second contact terminal 74: separating plate
75: first contact terminal 81: fine bubble generator
82: fine bubble mixing device 83: chemical tank
84: first processing module 85: second processing module
86: Dewatering device 87: Processing device
88: Feeding device 89: Bypass
103: upper cap 104: first exhaust passage
105: Inflow path 106: Union
107: second exhaust line 108: catalyst module
109: drain 110: upper tank
111: lower side reaction tank 112:

Claims (8)

(a) transferring the algae-containing influent water using the transfer device 88;
(b) removing the solids from the influent using the treatment device 87;
(c) generating fine bubbles in the algae-containing influent water from which the solids are removed by using the fine bubble generator 81;
(d) mixing the inflow water containing fine bubbles and algae with a flocculant using a fine bubble mixing device 82, and performing a primary treatment;
(e) electrically treating the primary treatment water in the first treatment module (84) to induce flocculation and floating, and separating the algae-containing suspended matter and treatment water;
(f) holding the treated water separated in step (e) in the second treatment module (85) to further remove the algae-containing float; And
(g) transferring the treated water from which the algae are further removed in the step (f) to the gypsum;
The processing device (87)
A cyclone, a cyclone, a multi-cyclone, and a filter,
The fine bubble mixing device 82 may include one or more selected from the group consisting of a generator and a line staple mixer,
The first processing module (84)
(I) an upper reaction tank 110 in which substances of the inflow fluid are suspended and separated;
(Ii) an inflow path (105) connected to an intermediate portion of the upper reaction tank (110) and through which the fluid flows;
(Iii) an upper cap 103 coupled with an upper portion of the upper reaction vessel 110;
(Iv) a first discharge path (104) connected through the lower end surface of the upper cap (103);
(V) a lower reactor 111 connected to the lower end of the upper reactor 110;
(Vi) a catalyst module (108) installed in the lower reaction tank (111);
(Iii) a second discharge path 107 coupled through an intermediate surface of the lower reaction tank 111; And
(Iii) a lower cap 112 coupled to a lower end of the lower reaction tank 111,
The second processing module (85)
(A) an upper reaction tank 110 in which substances of the inflow fluid are suspended and separated;
(B) an inflow path (105) connected to an intermediate portion of the upper reaction tank (110) and through which fluid flows;
(C) an upper cap (103) coupled with an upper portion of the upper reaction tank (110);
(D) a first discharge path (104) connected through the lower end surface of the upper cap (103);
(E) a lower reaction tank 111 connected to a lower end portion of the upper reaction tank 110;
(F) a second discharge path 107 coupled through an intermediate surface of the lower reaction tank 111; And
(C) a lower cap (112) coupled to a lower end of the lower reaction tank (111)
The catalyst module (108)
(i) a catalytic plate 71 to which electrons are supplied;
(ii) a separation guide (72) for fixing the catalyst plate (71) and supplying electricity;
(iii) a separation plate 74 for supplying power to the separation guide 72 and detachably attached thereto;
(iv) a first contact terminal 75 connected to the separation guide 72 to supply electricity to the catalyst plate 71; And
(v) a second contact terminal (73) connected to the separation plate (74) and supplying electricity to the separation guide (72).
The method according to claim 1,
Further comprising the step of separating water and sludge using the dewatering device (86) from the suspended solids separated in steps (e) and (f).
delete The method according to claim 1,
Wherein the step (f) further comprises an electrically treating step.
The method according to claim 1,
Wherein the second processing module (85) further comprises a catalyst module (108) installed in the lower reaction tank (111).
The method according to claim 1,
The first processing module 84 and the second processing module 85 are connected to the lower part of the upper reaction tank 110 and the upper part of the lower reaction tank 111, And a drain (109) for internal cleaning connected through the bottom surface.
6. The method of claim 5,
Wherein the catalyst module (108) has the following configuration:
(i) a catalytic plate 71 to which electrons are supplied;
(ii) a separation guide (72) for fixing the catalyst plate (71) and supplying electricity;
(iii) a separation plate 74 for supplying power to the separation guide 72 and detachably attached thereto;
(iv) a first contact terminal 75 connected to the separation guide 72 to supply electricity to the catalyst plate 71; And
(v) a second contact terminal 73 connected to the separating plate 74 to supply electricity to the separating guide 72;
8. The method of claim 1 or 7,
Wherein the voltage supplied to the fluid through the catalyst module (108) is between 2V and 50V, and the current is between 0.1A and 10.0A.

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