JP4088018B2 - Purification device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a purification device, and more particularly to a purification device for removing phosphorus from water to be treated.
[0002]
[Prior art]
When water bodies such as rivers and lakes become eutrophied, the water environment deteriorates due to the large-scale occurrence of blue sea bream. One of the main components that brings eutrophication of the water area is phosphorus, and removing this from the water area can effectively prevent the occurrence of large-scaled sea bream, and the removed phosphorus can be used as fertilizer. It can be reused as a resource, and it helps to save resources. Therefore, there is a need for a technology that can remove phosphorus efficiently and in a form that can be reused as fertilizer. Conventionally, a coagulation precipitation method is known as a typical technique for removing phosphorus for water purification. Further, for example, techniques described in Japanese Patent Laid-Open Nos. 9-361120 and 11-188383 are also known, and further, for example, techniques described in Japanese Patent Laid-Open No. 8-281261 are also known. Yes.
[0003]
[Problems to be solved by the invention]
In the coagulation precipitation method, it contains components that react with phosphate ions, which are the main form of phosphorus in water, to form phosphates, such as polyaluminum chloride, aluminum sulfate, ferric sulfate or ferric chloride. Is added to the water to be treated (raw water). As a result, suspended substances in the treated water aggregate, and at the same time, phosphate ions in the treated water react with the aggregating agents aluminum and iron to form phosphates, which aggregate together with the suspended substances. Therefore, phosphorus can be removed from the water to be treated by precipitating the aggregated floc. Such a coagulation-precipitation method is effective in terms of removing phosphorus, but it is difficult to remove phosphorus in a form that can be reused as a fertilizer resource. In other words, since the phosphorus precipitates by forming aggregated flocs together with the solid matter (floating matter) in the water to be treated, the concentration of phosphorus in the recovered sediment (sludge) is low, and the phosphorus component is taken out from the sediment. In addition, even if the precipitate is used as a fertilizer, the phosphorus content is insufficient. Especially in the coagulation sedimentation method, if the flocs to be formed are small, the sedimentation rate becomes slow, and it is inevitable that the coagulation sedimentation tank will be enlarged. Therefore, a large amount of coagulant is added to increase the processing efficiency. However, as a result, the precipitate is a mixture of a large amount of flocculant and a large amount of solid matter with a small amount of phosphate, making it impossible to recycle phosphorus. The coagulation sedimentation method is also used to remove phosphorus from sewage, in which case it is combined with biological treatment.
[0004]
On the other hand, in the techniques described in the above Japanese Patent Laid-Open Nos. 9-361120 and 11-188383, phosphorus is precipitated and recovered by adding calcium ions and the like after ozone oxidation of the coagulated sludge. This makes it possible to reuse phosphorus. However, in these conventional techniques, it is necessary to completely ionize phosphorus once in an ozone treatment or an anaerobic retention tank in order to separate sludge and phosphorus, and then it is necessary to add metal ions again to precipitate phosphorus. . Therefore, there exists a problem that the apparatus cost of phosphorus ionization or the operation cost becomes high. Moreover, since the particle size of the phosphate produced | generated at the time of phosphorus precipitation is small, it takes time to make it precipitate, and there also exists a problem that a phosphorus precipitation apparatus will enlarge.
[0005]
The technique described in the above Japanese Patent Application Laid-Open No. 8-281261 is based on a magnetic separation system in which phosphate ions are adsorbed on magnetic iron oxide fine particles and removed by magnetic separation, and phosphorus is buried in a large amount of sludge. Can be avoided. However, with this method, the amount of magnetic iron oxide necessary for adsorption increases to about 10 to 50 times the amount of phosphorus to be removed, and as a result, the concentration of phosphorus in the recovered product becomes as low as several percent, After all, there is great difficulty in reuse. Further, in order to efficiently adsorb phosphate ions in the water to be treated, magnetic iron oxide having strong phosphorus adsorption ability is required. Such a magnetic iron oxide is required to be produced by a special manufacturing method as described in JP-A-8-281261, and therefore the manufacturing cost is high and the running cost is high because it cannot be reused. turn into. Further, the magnetic iron oxide fine particles are likely to precipitate, and therefore strong stirring is always required, and the stirring power also increases the running cost.
[0006]
As described above, the conventional technology is effective as far as the phosphorus removal ability is concerned, but it is substantially impossible or possible in terms of recycling recovered phosphorus. However, the cost required for this is a major impediment to practicality. The present invention is made against the background of such a conventional situation, and it is possible to efficiently remove phosphorus as water purification and to recycle phosphorus as a fertilizer and the like. An object of the present invention is to provide a purification device that enables recovery at a low cost.
[0007]
[Means for Solving the Problems]
The present invention provides a purification apparatus for removing phosphorus from water to be treated by adding a metal salt to the water to be treated, and a magnetic phosphate produced by a reaction between metal ions and phosphate ions in the water to be treated. The phosphate production means to be generated, the solid-liquid separation means for separating the aggregated floc containing the phosphate in the treated water from the treated water, and the aggregated floc separated by the solid-liquid separation means, the PH adjustment method or Floc decomposition means for decomposing using mechanical decomposition, thermal decomposition, or oxidative decomposition method, and superconducting magnet type magnetic separation means for separating phosphate after decomposing the aggregated floc by this floc decomposition means A purifying device is disclosed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described. FIG. 1 schematically shows the configuration of the purification apparatus according to the first embodiment together with the flow thereof. The purification apparatus of the present embodiment is premised on being used for purification of water areas such as rivers and lakes, and includes a phosphate generation unit A and a magnetic separation unit B. The phosphate production unit A includes a stirring tank (reaction tank) 2, an iron ion storage tank (phosphate generation chemical storage tank) 6, and an alkali storage tank (pH adjustment chemical storage tank) 7 that form phosphate generation means. ing. To-be-treated water (raw water) 1 taken by a pump (not shown) from the water area is introduced into the agitation tank 2, and a phosphate generating agent is injected from the iron ion storage tank 6 through an injection valve 10. As the phosphate-generating agent, a metal salt is used in which metal ions are given in water, and a phosphate having magnetism is precipitated by a reaction between the metal ions and phosphate ions. Examples of such metal salts include ferrous sulfate, ferric sulfate, ferrous chloride, and ferric chloride that give iron ions. In addition, metal salts that give nickel ions, cobalt ions, or manganese ions can also be used as preferable ones. The phosphate-generating agent is added in an amount corresponding to the phosphate ion concentration of the raw water 1. That is, the phosphate ion concentration of the raw water 1 is measured, and the drug is added in an amount corresponding to the result. By performing such control, it is possible to avoid adding more drugs than necessary. For example, when an agent that provides iron ions is added, phosphate ions in raw water 1 react with iron ions to produce iron phosphate. This reaction is promoted by uniformly mixing iron ions with raw water by stirring in the stirring tank 2. That is, the stirring tank 2 functions to produce iron phosphate more efficiently.
[0009]
The present invention is based on the knowledge that a magnetic field as strong as that obtained with a superconducting magnet can attract even a relatively low magnetic material such as iron phosphate. Phosphorus is removed from the water to be treated by directly adsorbing and separating iron phosphate itself with a strong magnetic attraction force. This makes it possible to recover phosphorus in a form that facilitates recycling. That is, only the iron phosphate is magnetically adsorbed and collected without causing the precipitated iron phosphate to form aggregated flocs with solid suspended matters in the water to be treated. Accordingly, the phosphoric acid in the magnetic separation section B is recovered. It is a preferable condition that iron phosphate does not form aggregated floc during the separation of iron. For this purpose, the purification device of the present embodiment includes agglomeration preventing means. The aggregation preventing means of the present embodiment includes, for example, an alkali storage tank 7 that stores alkali such as NaOH, an injection valve 8 that controls the amount of alkali injected from the alkali storage tank 7 into the stirring tank 2, and a cover in the stirring tank 2. It comprises a pH sensor 11 for measuring the pH of treated water. In general, iron phosphate and solid suspended solids in the water to be treated are likely to aggregate in the range of pH 6-8, and aggregation is less likely to occur outside this range. Therefore, in this embodiment, the pH of the water to be treated in the stirring tank 2 is measured by the pH sensor 11, and an alkali such as NaOH is added from the alkali storage tank 7 while controlling the injection valve 8 so that the pH becomes 8 or more. I have to.
[0010]
The water to be treated in which iron phosphate is generated as described above is introduced into the magnetic separation section B through the pipe 12. The magnetic separation unit B includes a superconducting magnetic separator 25 as a magnetic separation means, a phosphorus storage tank 30, a cleaning cylinder 31 and various piping systems. The superconducting magnetic separator 25 has a structure in which a pair of magnetic filters 5 a and 5 b formed of a magnetic material such as stainless steel 430 are installed in the bore of the superconducting magnet 19. The magnetic filters 5a and 5b have a symmetric structure, and each have a folded channel structure. That is, it has a structure in which it enters from the inner flow path 17 and turns back while passing through the filter and flows out from the outer flow path 18. The magnetic filters 5a and 5b are integrally connected, and reciprocate in the integrated state so that the magnetic filter 5a and the magnetic filter 5b selectively enter the bore of the superconducting magnet 19 by this reciprocation. Has been. In the illustrated example, the magnetic filter 5a is contained in the bore of the superconducting magnet 19. In this case, the valves 15 and 22 are opened and the valves 16 and 23 are closed, and the water to be treated flowing through the pipe 12 is magnetic. It flows into the filter 5a and returns to the water area as treated water 24 through the pipe 20 while receiving magnetic separation of iron phosphate.
[0011]
A high magnetic field of 2T (Tesla) or more is applied to the magnetic filter 5a contained in the bore of the superconducting magnet 19 by the superconducting magnet 19, and a high magnetic field gradient is generated in the vicinity of the magnetic wire constituting the magnetic filter 5a. . Then, iron phosphate in the for-treatment water flowing in the magnetic filter 5a is magnetized by the high magnetic field and is attracted to the magnetic fine wire of the magnetic filter 5a. Since this attractive force is proportional to the product of the magnetization of iron phosphate and the magnetic field gradient in the vicinity of the magnetic wire, the higher the magnetic field intensity generated by the superconducting magnet 19, the higher the iron phosphate removal rate. Here, the water to be treated flowing in the magnetic filter 5a contains various suspended substances in addition to iron phosphate, but these have lower magnetic susceptibility than iron phosphate. It is not attracted by the magnetic conditions to be attracted and is returned to the water area while being contained in the treated water 24.
[0012]
If the adsorption and separation of iron phosphate by the magnetic filter 5a is continued as described above, iron phosphate is gradually deposited on the magnetic filter 5a, and the separation performance of the magnetic filter 5a is accordingly lowered. Then, after continuing water flow for a predetermined time, it switches to the magnetic filter 5b. For this purpose, the integrally connected magnetic filters 5a and 5b are moved to the left, or the superconducting magnet 19 is moved to the right, so that the magnetic filter 5a is brought out to the low magnetic field space outside the bore of the superconducting magnet 19, and instead the magnetic filter 5 b is positioned in the high magnetic field space in the bore of the superconducting magnet 19. At the same time, the valves 15 and 22 are closed, the valves 16 and 23 are opened, and the water to be treated is guided to the magnetic filter 5b, and the separation operation is performed by the magnetic filter 5b. During this time, the magnetic filter 5a is washed and regenerated in a low magnetic field space. For this purpose, the valves 26 and 27 are opened, washing air or washing water is injected from the cylinder 31 to wash away the iron phosphate held by the magnetic filter 5 a, and the washed-out iron phosphate is stored in the phosphorus storage tank 30. The magnetic filter 5b is also cleaned and regenerated during the separation operation of the magnetic filter 5a. In this case, the valves 28 and 29 are opened. In this embodiment, cleaning air and cleaning water are supplied from the cylinder 31, but it is also possible to use the treated water 24 for cleaning instead.
[0013]
As described above, the present purification device can separately separate and recover phosphorus that causes eutrophication as iron phosphate without mixing it with other solid suspended substances. For this reason, the recovered iron phosphate has a high purity, and the recovered phosphorus can be easily reused. As a form of reuse of recovered phosphorus, fertilizer is particularly preferable because recovered phosphorus is in the form of iron phosphate. The recovered iron phosphate can be used as a fertilizer in an almost intact state, but a more excellent fertilizer can be obtained by appropriately adding nitrogen, potassium, or the like. In addition, this purification device can use low-cost iron sulfate or iron chloride as the chemical used for the precipitation of phosphorus, and can use the same amount as the phosphate ion concentration of the water to be treated. As a result, the running cost can be significantly reduced as compared with the conventional method.
[0014]
Here, an experimental example is described for reference. In the experiment, ferric sulfate was added to test water containing phosphorus, and water was passed through the superconducting magnetic separator with the pH controlled to 8 or higher. The applied magnetic field of the superconducting magnetic separator was 2T. As a result, 77% of phosphorus could be removed. As described above, since the attractive force in the magnetic separator is proportional to the product of the magnetization of iron phosphate and the magnetic field gradient in the vicinity of the magnetic wire, it is considered that the removal rate can be further increased by using a higher magnetic field. In the case of the present invention using the superconducting magnet system, it is easy to obtain a high magnetic field. For example, even a superconducting magnet composed of an inexpensive NbTi superconducting wire can easily generate a high magnetic field of about 5 to 7T. Further, when a superconducting magnet formed of a superconducting material such as Nb3 Sn or Nb3 Al or a high temperature superconducting material is used, a higher magnetic field can be generated. Therefore, according to the present invention, it can be seen that an extremely high phosphorus removal rate can be achieved, and the processing speed is high and the processing is highly efficient.
[0015]
FIG. 2 schematically shows the configuration of the purification apparatus according to the second embodiment together with the flow thereof. The purification apparatus of this embodiment is different from that of the first embodiment in that a solid-liquid separation part C and a floc decomposition part D are added between the phosphate production part A and the magnetic separation part B. Yes. Hereinafter, this difference will be described mainly. In the present embodiment, an aqueous iron coagulant is added to the water to be treated from the iron ion storage tank 6 as a chemical agent, and the pH of the stirring tank 2 is controlled to increase cohesion. Therefore, iron phosphate forms agglomerated flocs together with suspended solids in the water to be treated in the stirring tank 2. The agglomerated floc is precipitated in a precipitation tank 3 provided as a solid-liquid separation means in the solid-liquid separation part C, and becomes sludge and separated from the water to be treated. A sludge extraction pipe 14 is connected to the sedimentation tank 3, and the sludge extracted by the sludge extraction pipe 14 is guided to a pH adjustment tank (decomposition tank) 4 provided as a floc decomposition means in the flock decomposition section D. . In the pH adjustment tank 4, the pH is increased by adding alkali from the alkali storage tank 7 while controlling the valve 9 by the pH sensor 32, thereby reducing the aggregation effect of the flocculant and decomposing the aggregated floc. Since the water to be treated containing iron phosphate in a non-aggregated state is obtained by the decomposition of the agglomerated floc, this is passed through the magnetic separation part B, and magnetic separation is performed in the same manner as in the first embodiment.
[0016]
According to the present embodiment, the flocs flocs are once formed and subjected to magnetic separation after solid-liquid separation from the water to be treated. Therefore, most of the water to be treated introduced into the apparatus after taking water from the water area is solidified. In the liquid separation part C, the supernatant water 13 of the precipitation tank 3 can be returned to the water area. Therefore, it is only necessary to pass a remarkably small amount of water to be treated compared to the total amount of water to be treated introduced from the water area to the apparatus. B can be greatly reduced in size, and the processing capability can be greatly increased if the magnetic separation unit B has the same size.
[0017]
In the second embodiment described above, the precipitation method using the precipitation tank 3 is used for solid-liquid separation, but instead, for example, a specific gravity difference separation method, a sand addition high-speed aggregation method, a magnetic separation method, or the like can be used. In the case of using the magnetic separation method, for example, it is preferable to add magnetic particles such as magnetite together with the flocculant and perform magnetic separation by the magnetic seed type magnetic separation method. Further, in this embodiment, the treated water 24 is discharged as it is into the water area, but it is also preferable that the treated water 24 is subjected to a suspended solid removal process such as coagulation sedimentation. That is, the treated water 24 contains suspended solids at a high concentration by the treatment up to the solid-liquid separation section C, and therefore, the treated water 24 is in a state where it can be removed more efficiently. Therefore, by taking advantage of this condition and performing the suspended matter removal treatment, the purification by removing the suspended matter can be efficiently performed together with the removal of phosphorus. When the suspended water removal treatment is performed on the treated water 24 by the coagulation sedimentation method, if the coagulant in the iron ion storage tank 6 or the alkali in the alkali storage tank 7 is used, it is not necessary to increase the storage tank, thereby reducing the size and cost of the apparatus. Can be planned. The sludge generated by removing suspended solids from the treated water 24 can be made into a high-quality fertilizer by adding recovered iron phosphate thereto, and by doing so, the reusability can be further enhanced. . In this embodiment, the pH adjustment method is used for the decomposition of the aggregated flocs. However, mechanical decomposition, thermal decomposition, oxidative decomposition using ozone or hydrogen peroxide, or the like can be used instead.
[0018]
The purification apparatuses according to the first and second embodiments described above can be used by installing them on land, or can be used in the form of onboard processing by mounting all or part of them on a ship. . Furthermore, it is also possible to apply the water area itself about the phosphate production | generation part. In other words, if necessary, a part of the medicine can be partitioned and the chemical can be directly introduced into the water area, and then the treated water into which the chemical has been introduced is guided to the magnetic separation unit to perform the magnetic treatment. Further, in each of the above embodiments, the stirring tank 2 and the pH adjustment tank 4 are provided to promote the reaction by stirring there, but instead of this, stirring action is obtained by using a meander of a static mixer or piping. It is also possible to obtain a structure that promotes the reaction. Further, in each of the above embodiments, it is assumed that the purification device is used for purification of water areas such as rivers and lakes, but the purification device according to the present invention has the same effect even if it is used for dephosphorization purification of sewage water or factory waste water. Can be obtained. In the case of sewage water treatment, raw sewage can be treated water, or treated water treated by the activated sludge method can be treated water.
[0019]
The present invention is characterized by the use of a superconducting magnet system for magnetic separation. However, a cooling system such as liquid helium and a refrigerator conduction cooling system can be used for cooling the superconducting magnet. For example, it is not necessary to install a refrigerant tank, so that space can be saved and operability can be improved.
[0020]
FIG. 3 shows a flow of the purification apparatus according to the third embodiment. Since the metal salt as described above is used as a drug, a significant amount of metal hydroxide (or iron hydroxide when the metal ion is an iron ion) is generated at the same time as the phosphate is formed. This metal hydroxide can also be recovered by superconducting magnet type magnetic separation. However, in order to facilitate the reuse of phosphate, it is desirable to collect phosphate and metal hydroxide separately. In order to collect the phosphate and the metal hydroxide separately, the fact that the magnetism of the phosphate and the metal hydroxide is different is used. Specifically, the superconducting magnetic separator is provided with a plurality of magnetic filters having different magnetic forces, and a magnetic filter having a low magnetic force is disposed on the upstream side. When the water to be treated is passed through such a superconducting magnetic separator, each of the magnetic filters can separate and recover each of phosphate (iron phosphate) and metal hydroxide (iron hydroxide). The recovered iron hydroxide can be reused as iron ions for addition again by dissolving with an acid. On the other hand, the recovered iron phosphate can be reused as fertilizer as in the case of the above embodiments. The example in FIG. 3 is based on the purification device in FIG. 2, but the configuration of the present embodiment can be similarly applied to the purification device in FIG.
[0021]
FIG. 4 shows a flow of the purification apparatus according to the fourth embodiment. This embodiment is a modification of the third embodiment and uses magnetic separation to separate the aggregated floc from the water to be treated. In order to magnetically separate the agglomerated flocs, the magnetic particles are taken into the agglomerated flocs by injecting the magnetic particles 34 on the upstream side of the floc forming unit 2 (which the agitation tank 2 corresponds), and the magnetic particles are used to magnetically Perform separation. Magnetic particles that are more magnetic than phosphates and metal hydroxides are used, and the magnetic particles that remain in the water to be treated after decomposition of the aggregated floc are separated from the phosphates and metal hydroxides in the superconducting magnetic separator 25. Collect upstream from the separation position. The collected magnetic particles 35 are reused as added magnetic particles 34.
[0022]
FIG. 5 and FIG. 6 show the configuration of a superconducting magnetic separator that can be used in the magnetic separation part of the purification apparatus in the fourth embodiment. FIG. 5 schematically shows the cross-sectional structure, and FIG. 6 schematically shows the planar structure. The superconducting magnetic separator according to the present embodiment includes three magnetic filters 42, 43, and 44 for magnetically separating each separation target (recovered object) of phosphate, metal hydroxide, and magnetic particles. Have. These magnetic filters 42, 43, 44 are arranged so that their magnetic forces are different within a magnetic field space formed by one superconducting magnet 45. Specifically, three magnetic filters 42, 43, 44 are provided along the flow path of the water to be treated that is vertically provided so as to flow in from the lower inlet 41 and flow out to the upper outlet 49. These are arranged in series in this order so that each distance from the superconducting magnet 45 is different. That is, the three magnetic filters 42, 43, and 44 receive the magnetic field strength corresponding to the distance from the superconducting magnet 45. The superconducting magnet 45 is insulated from the outside by being installed in a vacuum vessel, and is kept in a superconducting state by being cooled by the refrigerator 48. Then, a magnetic field is generated by supplying current from a power source 47, and once the magnetic field is generated, it is possible to operate in the permanent current mode.
[0023]
The magnetic filter 42 at the lowermost part (uppermost stream side) has the smallest magnetic force and is used for attracting and separating magnetic particles (for example, magnetite and hematite) having the strongest magnetic force among the three kinds of objects to be collected. The magnetic filter 43 and the magnetic filter 44 on the upper side (downstream side) increase the magnetic force in this order, and attract and separate phosphates or metal hydroxides according to the respective magnetic forces. Each of the magnetic filters 42, 43, 44 is formed in a donut shape and can be rotated. By this rotation, the portion located in the flow path of the water to be treated moves to the cleaning units 42a, 43a, 44a, Therefore, it undergoes cleaning regeneration by injection of high-pressure water or high-pressure air. The separation object that has been peeled off from the magnetic filter by washing is collected in the collection tank 50. These cleaning parts 42a, 43a, 44a are arranged to be shifted by 120 ° so that they do not overlap each other by arranging the magnetic filters 42, 43, 44 as shown in FIG. The cleaning units 42a, 43a, and 44a are designed so as not to receive the magnetic field of the superconducting magnet 45 as much as possible. Specifically, the cleaning portions 42a, 43a, and 44a are arranged as far as possible from the magnetic field space of the superconducting magnet 45, and the superconducting magnet 45 is covered with a magnetic shield 46 formed of a magnetic material such as iron.
[0024]
The configuration in which a plurality of magnetic filters 42, 43, 44 are arranged in a magnetic field space formed by one superconducting magnet 45 as in the present embodiment so that each magnetic force is different from each other separately. There is an advantage that the apparatus structure in the case where it is necessary to perform magnetic separation can be reduced in size and cost can be reduced. That is, for magnetic separation of a plurality of separation objects separately, a superconducting magnetic separator can be provided for each separation object, but compared to this, the configuration of the present embodiment can reduce the size of the apparatus. Cost reduction can be achieved.
[0025]
【The invention's effect】
As described above, according to the present invention, phosphorus can be efficiently removed as water purification, and phosphorus can be recovered at a low cost in a form that can be easily reused as fertilizer. It becomes.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a purification device according to a first embodiment together with the flow thereof.
FIG. 2 is a diagram showing a configuration of a purification device according to a second embodiment together with the flow thereof.
FIG. 3 is a diagram showing a flow of a purification device according to a third embodiment.
FIG. 4 is a diagram showing a flow of a purification device according to a fourth embodiment.
FIG. 5 is a diagram schematically showing a cross-sectional structure of a superconducting magnetic separator according to another embodiment.
6 is a diagram schematically showing a planar structure of the superconducting magnetic separator of FIG.
[Explanation of symbols]
1 Water to be treated 2 Reaction tank (phosphate production means)
3 Settling tank (Solid-liquid separation means)
4 Decomposition tank (floc disassembling means)
5a, 5b Magnetic filter 6 Iron ion storage tank 7 Alkali tank 19 Superconducting magnet 25 Superconducting magnetic separator (magnetic separation means)

Claims (4)

In a purification device for removing phosphorus from the water to be treated, phosphoric acid is produced by adding a metal salt to the water to be treated and forming a magnetic phosphate produced by a reaction between metal ions and phosphate ions in the water to be treated. The salt generation means, the solid-liquid separation means for separating the aggregated floc containing the phosphate in the treated water from the treated water, and the aggregated floc separated by the solid-liquid separating means are subjected to a PH adjustment method or mechanical decomposition or A purifying apparatus comprising: floc decomposition means for decomposing using thermal decomposition or oxidative decomposition method; and superconducting magnet type magnetic separation means for separating phosphate after decomposing the aggregated floc by the floc decomposition means . 2. The purification according to claim 1, further comprising an aggregation preventing means for controlling alkali input according to a pH value of the water to be treated to prevent aggregation of the phosphate produced by the phosphate producing means. apparatus. Claims 1, which is adapted to separate separately from the phosphates in different magnetic conditions the metal hydroxide to produce with phosphate by the added metal salts and separation of the phosphate The purification device according to any one of 2 .   The magnetic separation means includes a plurality of magnetic filters, and the plurality of magnetic filters are arranged so that each magnetic force is different in the magnetic field space generated by one superconducting magnet, The purification apparatus according to any one of claims 1 to 3, wherein the salt and other separation objects are separated separately.

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