JP2013029390A - Processing method for waste liquid containing metal atom, and adsorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method and an adsorbent that can efficiently and easily remove radioactive strontium from a waste liquid containing metal atoms, especially, radioactive strontium.SOLUTION: There is provided a processing method for a waste liquid that removes and collects metal atoms in a waste liquid, the processing method including a process of adding (a) a phosphate compound and (b) a water-soluble metal salt containing at least one kind of metal selected from the group consisting of potassium, rubidium, cesium, strontium, barium, iron, cobalt, nickel, copper, and zinc to the waste liquid.

Description

  The present invention relates to a method of treating a waste liquid by adsorbing and removing the metal atoms from a waste liquid containing metal atoms, particularly radioactive strontium, and an adsorbent for removing the metal atoms. And an adsorbent comprising a phosphoric acid compound and an alkali metal, alkaline earth metal or transition metal.

  In nuclear facilities such as nuclear power plants and spent nuclear fuel reprocessing plants, waste liquids containing various radioactive substances are generated. Radioactive waste liquid is divided into radioactive material and water by operations such as evaporation, concentration, ion exchange, and coagulation sedimentation. Water from which radioactive material has been sufficiently removed is released, and the concentrated radioactive material is used for vitrification, asphalt solidification, etc. Fixed and stored by method.

  Among these methods, the evaporative concentration method is very efficient in separating water and radioactive materials, that is, decontamination efficiency, but the construction cost and operation cost of the evaporation equipment are high, and the material of the evaporator is corroded. There are disadvantages such as easy. On the other hand, the ion exchange resin method and the coagulation sedimentation method have the disadvantage that the decontamination efficiency is low, although the construction cost and operation cost of the equipment are small.

  The radioactive waste liquid usually contains sodium salt used to clean the nuclear fuel material extractant, so the evaporation concentration method has a problem that sodium salt such as sodium nitrate precipitates in the residue of the kettle and the concentration rate does not increase. In the ion exchange resin method, there is a problem that the adsorption amount of monovalent cations such as cesium decreases due to the high concentration of sodium nitrate and the decontamination efficiency decreases. There exists a problem that a decontamination coefficient falls by existence.

  Radioactive substances in the waste liquid include various elements such as ruthenium and zirconium, which have low solubility as hydroxides, alkali metals such as cesium and strontium, which have high solubility as hydroxides, and alkaline earth metals. ing. Of these, heavy metals such as ruthenium and zirconium are effective by the coagulation precipitation method, in which the liquidity is made alkaline and precipitated by coprecipitation with iron hydroxide and the like. In addition, it is very difficult to remove alkaline earth metals.

  As a method for removing alkali metals, alkaline earth metals and the like, an ion exchanger method has been widely studied. As an adsorbent for alkaline earth metals such as strontium and uranium, titanic acid is known. For example, the surface area of titanic acid as shown in JP-A-57-140644 (Patent Document 1) is extremely high. A composite adsorbent molded product of titanic acid and an acrylonitrile-based polymer, which improves the adsorbing capacity by improving the handleability and at the same time, is effective.

  However, the adsorption and removal ability of strontium titanate is not so high, and strontium cannot be completely removed from the radioactive liquid waste, so it must be used in combination with other methods and has a higher adsorption removal ability. Development of agents is desired.

Sheng-Heng Tan et al., Hydrothermal removal of Sr 2+ in aqueous solution via formation of Sr-substituted hydroxyapatite, "Journal of Hazardous Materials," 179 (2010) 559-563 ( Non-Patent Document 1), ²³⁵ U and Disclosed is a method for removing radioactive strontium ( ⁹⁰ Sr and ⁸⁹ Sr) from waste produced by fission of ²³⁹ Pu as Sr-substituted hydroxyapatite with Ca ions and phosphate compounds. This method is described as being able to remove 99.5% or more of strontium by adding sodium hydrogen phosphate and sodium tripolyphosphate to an aqueous solution containing Sr and Ca, and performing heat treatment at 160 ° C. for 14 hours in an autoclave. Has been. However, since this method requires heat treatment at 160 ° C. for 14 hours in an autoclave, it is practically impossible to treat a large amount of radioactive liquid waste, and improvement is desired.

JP-A-57-140644 Sheng-Heng Tan et al., Hydrothermal removal of Sr2 + in aqueous solution via formation of Sr-substituted hydroxyapatite, “Journal of Hazardous Materials,” 179 (2010) 559-563

  Accordingly, an object of the present invention is to provide a treatment method and an adsorbent capable of efficiently and easily removing the radioactive strontium from a waste solution containing metal atoms, particularly radioactive strontium.

  As a result of diligent research in view of the above-mentioned object, the present inventors rapidly added a radioactive compound such as tripolyphosphoric acid and a water-soluble inorganic salt of a metal such as barium to a waste liquid containing radioactive strontium, thereby promptly producing a radioactive material. The present inventors have found that a precipitate containing strontium is generated, and that radioactive strontium can be removed from the waste liquid.

That is, the waste liquid treatment method of the present invention is a method for removing and recovering metal atoms in the waste liquid,
(a) a phosphate compound;
(b) having a step of adding a water-soluble metal salt containing at least one metal selected from the group consisting of potassium, rubidium, cesium, strontium, barium, iron, cobalt, nickel, copper and zinc. Features.

  It is preferable to include a step of adding a flocculant after the step of adding the phosphoric acid compound and the water-soluble metal salt.

  The phosphoric acid compound and the water-soluble metal salt are preferably added to the waste liquid heated to 50 to 80 ° C.

  The phosphate compound preferably contains at least one selected from the group consisting of phosphate, hydrogen phosphate, pyrophosphate, tripolyphosphate, tetrapolyphosphate, and metaphosphate.

  The water-soluble metal salt is preferably at least one selected from the group consisting of halides, nitrates and sulfates of the metals.

  The flocculant is preferably an inorganic flocculant and / or an organic polymer flocculant.

  The inorganic flocculant is preferably at least one selected from the group consisting of aluminum sulfate, aluminum chloride, polyaluminum chloride, ferric chloride, and polyferric sulfate.

  The organic polymer flocculant is at least one selected from the group consisting of cationic organic polymer flocculants, anionic organic polymer flocculants, nonionic organic polymer flocculants, and amphoteric organic polymer flocculants. Preferably there is.

  The step of adding the flocculant preferably comprises the step of adding and mixing the polymer flocculant after adding and mixing the inorganic flocculant and / or the polymer flocculant.

  The adsorbent of the present invention for adsorbing metal atoms in the waste liquid comprises a phosphoric acid compound and an alkali metal, alkaline earth metal or transition metal.

The waste liquid treatment method and the adsorbent of the present invention can selectively and rapidly remove metal atoms, particularly strontium, in the waste liquid. Therefore, radioactive strontium ( ⁹⁰ Sr and ⁸⁹ Suitable for removing Sr).

[1] Waste liquid treatment method The waste liquid treatment method of the present invention is for removing and recovering metal atoms in a waste liquid.
(a) a phosphate compound;
(b) by adding a water-soluble metal salt containing at least one metal selected from the group consisting of potassium, rubidium, cesium, strontium, barium, iron, cobalt, nickel, copper and zinc; In this method, a precipitate containing atoms is generated and the precipitate is recovered.

  The waste liquid treatment method of the present invention is particularly effective for removing and recovering radioactive strontium from, for example, a waste liquid containing a radioactive substance because alkaline earth metals such as strontium can be selectively precipitated.

  In the method of the present invention, after the phosphoric acid compound and the water-soluble metal salt are added to an aqueous solution containing an alkaline earth metal such as strontium, a precipitate is rapidly formed by sufficiently stirring. In order to sufficiently complete the reaction and to sufficiently precipitate the precipitate, it is preferably left for 10 minutes or more after mixing, more preferably for 1 hour or more, and most preferably for 5 hours or more.

  When a phosphoric acid compound and a water-soluble metal salt are added to an aqueous solution of strontium or the like, a salt of phosphoric acid and a metal is formed, and at the same time, an alkaline earth metal is incorporated into the salt of phosphoric acid and a metal to form a composite By forming and precipitating the salt, the alkaline earth metal in the waste liquid can be efficiently and rapidly removed. These treatments can be performed at room temperature. However, particularly when it is desired to perform the treatment quickly, the waste liquid is preferably heated to a temperature higher than 25 ° C and lower than 90 ° C. More preferably, it is carried out at ° C.

(1) Water-soluble metal salt The water-soluble metal salt is preferably added in an amount of 10 equivalents or more, more preferably 100 equivalents or more, more preferably 1000 equivalents or more with respect to an alkaline earth metal such as strontium contained in the waste liquid. Most preferably, it is added. When the addition amount is less than 10 equivalents, the removal efficiency of alkaline earth metals such as strontium is lowered. Moreover, since the required amount of a phosphoric acid compound will increase when it is added in a large amount, it is preferably used in an amount of 10,000 equivalent or less with respect to an alkaline earth metal such as strontium.

  The water-soluble metal salt is preferably at least one selected from the group consisting of alkali metal, alkaline earth metal or transition metal halides, nitrates and sulfates. The alkali metal is preferably potassium, rubidium or cesium, the alkaline earth metal is preferably barium, and the transition metal is preferably iron, cobalt, nickel or copper. The water-soluble metal salt is most preferably a barium salt such as barium chloride or barium nitrate.

(2) Phosphoric acid compound The phosphoric acid compound is preferably added in an amount of 1/10 equivalent or more, more preferably 1 equivalent or more, most preferably 10 equivalents or more with respect to the water-soluble metal salt. . The upper limit is not particularly limited, but practically it is preferably used at 100 equivalents or less with respect to the water-soluble metal salt.

As the phosphoric acid compound, phosphate, amino phosphate, anhydrous phosphate, triphosphate, tetraphosphate, condensed phosphate, etc. can be used, but phosphate, hydrogen phosphate and condensed Phosphate is preferred, in particular condensed phosphate is preferably used alone or in combination with phosphate and / or hydrogen phosphate. The condensed phosphate is a salt of an acid obtained by dehydration condensation of orthophosphoric acid (H ₃ PO ₄ ), and is not particularly limited, but pyrophosphate, tripolyphosphate, tetrapolyphosphate and metaphosphate. Is preferred. Among the metaphosphates [(PO ₃ ) _n ], lower polyphosphates (n = 6 or less) are particularly preferable, pyrophosphates and tripolyphosphates are more preferable, and tripolyphosphates are particularly preferable.

  The phosphate compound may contain a metal, and the contained metal is preferably an alkali metal, an alkaline earth metal, a transition metal, Al or the like. Na and K are preferable as the alkali metal, Mg and Ca are preferable as the alkaline earth metal, and Fe and Zn are preferable as the transition metal.

  As a preferred use example of the phosphoric acid compound, a combination of hydrogen phosphate and polyphosphoric acid is preferable, and a combination of disodium hydrogen phosphate and tripolyphosphoric acid is particularly preferable. The ratio of hydrogen phosphate and polyphosphoric acid is not limited, but the molar ratio of hydrogen phosphate / polyphosphoric acid is preferably in the range of 1/110 to 10/1, more preferably in the range of 1/2 to 5/1. preferable.

(3) Flocculant The precipitate can be removed from the waste liquid by methods such as filtration and decantation, but can be further agglomerated and solidified by adding a flocculant.

  The amount of the flocculant added is not particularly limited as long as the amount of the flocculent can be sufficiently settled. In addition, sufficient sedimentation means that 99% or more of the generated aggregates have settled. Therefore, in practice, the amount of flocculant added may be adjusted as appropriate to achieve such removal efficiency. For example, when an anionic flocculant is used, the phosphate compound and water-soluble metal salt added to the waste liquid are used. If the flocculant is added in an amount of about 0.1 to 10% with respect to the total amount, sufficient aggregation and precipitation can be achieved.

  As a method for efficiently separating the aggregate from the waste liquid to which the flocculant has been added, there are filtration, decantation, centrifugation, a method of adsorbing to a non-woven fabric, etc., but filtration or decantation is easy for handling. preferable. By allowing the flocculant to stand for a certain period of time after adding the flocculant, the flocculent precipitates on the bottom of the treatment tank, so the supernatant is filtered or removed by decantation. For decantation, methods such as extraction from a drain valve, suction or suction by a pump, use of a siphon, etc., or tilting the treatment tank itself and discharging from the upper end of the wall surface are used. Furthermore, natural filtration using a nonwoven fabric as a filter is more preferable because it is excellent in handling after filtration. The nonwoven fabric is preferably made of rayon, polyester, polypropylene or the like, but is not limited thereto.

  As a method for using the flocculant, a method in which an inorganic flocculant and an organic polymer flocculant are used in combination is preferable. Only with the inorganic flocculant, the mechanical strength of the colloidal particles generated by the aggregation is not so large, and there is a limit to the size and settling speed of the particles. By using the organic polymer flocculant in combination, coarse particles (floc) having a large particle size and a high sedimentation speed can be obtained.

  Examples of inorganic flocculants include sodium chloride, potassium chloride, sodium bromide, calcium chloride, sodium sulfate, aluminum sulfate (sulfate band), aluminum chloride, polyaluminum chloride, ferric chloride, ferrous sulfate, and polysulfate Iron and other polyvalent metal salts used in general water treatment can be used, and among them, aluminum sulfate, aluminum chloride, polyaluminum chloride, ferric chloride and polyferric sulfate are preferable. These inorganic flocculants are used alone or in combination.

  The organic polymer flocculant is preferably selected from cationic organic polymer flocculants, anionic organic polymer flocculants, nonionic organic polymer flocculants, and amphoteric organic polymer flocculants. In particular, a combination of a cationic organic polymer flocculant and an anionic organic polymer flocculant, or an amphoteric organic polymer flocculant is preferred.

  Examples of cationic organic polymer flocculants include polyethyleneimine, halogenated polydiallylammonium, water-soluble aniline resin, polythiourea, polyacrylamide cation-modified products modified with formalin and amines, and cationic vinyl lactams. Acrylamide copolymer, cyclized polymer of diallylammonium halide, copolymer obtained by reacting diamine with copolymer of isobutylene and maleic anhydride, vinyl imidazoline polymer, polymer of dialkylaminoethyl acrylate, alkylene dichloride Condensation product of olefin and alkylenepolyamine, polycondensation product of dicyandiamide and formalin, polycondensation product of aniline and formalin, copolymer of amines and epichlorohydrin, copolymer of ammonia and epichlorohydrin Copolymers of amines with aspartic acid, acrylic polymers, and the like having a quaternary ammonium salt in the side chain.

  Examples of the amines include methylamine, ethylamine, n-propylamine, isopropylamine, methoxypropylamine, butylamine, amylamine, allylamine, hexylamine, caprylamine, laurylamine, stearylamine, oleylamine, monomethylaminopropylamine, and benzylamine. Alkylamines and cyclic amines such as piperidine and pyrrolidine, polyethylenepolyamines, aminopropylethanolamine, methyliminobispropylamine, monomethylaminopropylamine, dialkylaminopropylamine, hydroxyethylaminopropylamine, diethylaminoethylamine, tetramethylenediamine, Examples include hexamethylene diamine.

  Examples of the anionic organic polymer flocculant include sodium polyacrylate, maleic acid copolymer, partially hydrolyzed polyacrylamide, polyacrylamide-acrylic acid copolymer, and partially sulfomethylated polyacrylamide.

  Nonionic organic polymer flocculants include polyacrylamide, polyethylene oxide, urea-formalin resin, polyaminoalkyl methacrylate, chitosan, and the like.

  The amphoteric organic polymer flocculant is a polymer flocculant having a cationic group and an anionic group in one molecule. Examples of cationic groups include tertiary amines, neutralized salts thereof, and quaternary salts. Examples of anionic groups include carboxyl groups, sulfone groups, and salts thereof. In particular, amphoteric polymer flocculants having a carboxyl group are preferred. In addition to these ionic components, a nonionic component may be contained. More specifically, examples of the anionic monomer unit include acrylic acid, methacrylic acid, and alkali metal salts thereof. Cationic monomer units include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, allyl dimethylamine or neutralized salts thereof, quaternary Examples include salts. Nonionic monomer units include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide and the like.

  Zwitterionic organic polymer flocculants include dimethylaminoethyl acrylate / acrylic acid / acrylamide copolymer, dimethylaminoethyl methacrylate / acrylic acid / acrylamide copolymer, dimethylaminopropylacrylamide hydrochloride / acrylic acid / acrylamide copolymer Preferred are a polymer, a Mannich modified product of dimethylaminoethyl acrylate / acrylic acid copolymer, sodium acrylate / acrylamide copolymer, and the like.

  In the case of using a plurality of flocculants, the order of addition and the addition method are not particularly limited, but in order to strengthen the bond of the agglomerates and coarsen the floc, (a) inorganic flocculants and cationic organic polymer flocculants After adding an agent and stirring and mixing, an anionic organic polymer flocculant is further added and stirred and mixed. (B) An inorganic flocculant, a cationic organic polymer flocculant and an anionic organic polymer flocculant are added and stirred. After mixing, add anionic organic polymer flocculant and stir and mix, (c) Add inorganic flocculant and stir and mix, then add cationic organic polymer flocculant and anionic organic polymer flocculant A method of stirring and mixing, (d) a method of adding an inorganic flocculant and stirring and mixing, then a method of adding an amphoteric organic polymer flocculant and stirring and mixing, and (e) an inorganic flocculant and an amphoteric organic polymer flocculant. After adding and mixing with stirring, both How to mixing and stirring were added down organic polymer flocculant, and the like are preferably used. The method for adding the flocculant is not limited to the above-described method, and various combinations are conceivable, and it is preferable to select the method appropriately depending on the type of waste liquid.

  When using a cationic organic polymer flocculant or an anionic polymer flocculant, in order to make the polymer flocculant work effectively, the waste liquid is added to the pH according to each polymer flocculant before adding them. It is preferable to adjust. When a cationic organic polymer flocculant is used, it is weakly acidic. When an anionic polymer flocculant is used, it is weakly alkaline. The amount can also be reduced. Moreover, when using together a cationic organic polymer flocculant and an anionic polymer flocculant, when using an amphoteric organic polymer flocculant, it is preferable to adjust to pH near neutrality. In particular, after adding the inorganic flocculant, the pH is large and may be on the acidic side or the alkaline side. Therefore, it is preferable to adjust the pH in order to increase the aggregation efficiency of the organic polymer flocculant.

  When an inorganic flocculant and an organic polymer flocculant are used in combination, the amount of flocculant added is 10 to 1000 mg / L, preferably 20 to 500 mg, of inorganic flocculant (anhydrous basis) based on the amount of waste liquid. / L, cationic organic polymer flocculant 5-100 mg / L, preferably 10-50 mg / L, anionic organic polymer flocculant 2-50 mg / L, preferably 5-30 mg / L, both The ionic organic polymer flocculant is added in an amount of 5 to 100 mg / L, preferably 10 to 50 mg / L.

  Since the method of the present invention can efficiently remove the alkaline earth metal from a waste liquid having a low concentration of alkaline earth metal such as radioactive strontium, it is treated beforehand with an existing adsorbent such as titanic acid or zeolite. After the radioactive substance is removed to some extent, it is preferable to remove the radioactive strontium remaining in a trace amount by the method of the present invention. Thus, radioactive strontium can be more efficiently removed by treating the waste liquid in two stages.

[2] Adsorbent A salt comprising a phosphate compound and an alkali metal, alkaline earth metal or transition metal is highly effective as an adsorbent for adsorbing metal atoms in the waste liquid, especially alkaline earth metals such as strontium. Demonstrate.

  The adsorbent can be produced by mixing a phosphoric acid compound with a water-soluble salt of the alkali metal, alkaline earth metal or transition metal. The amount of these compounds used when mixing the phosphoric acid compound and the water-soluble metal salt may be the same as in the method of the present invention.

  The said phosphoric acid compound can use the same thing as what is used by the method of this invention.

  The water-soluble metal salt is preferably at least one selected from the group consisting of halides of alkali metals, alkaline earth metals or transition metals, nitrates and sulfates, and examples of the alkali metals include potassium and rubidium. Alternatively, cesium is preferable, calcium, strontium, or barium is preferable as the alkaline earth metal, and iron, cobalt, nickel, or copper is preferable as the transition metal. The water-soluble metal salt is particularly preferably an alkaline earth metal salt, and most preferably a barium salt such as barium chloride or barium nitrate.

  The adsorbent is used after being added to a waste liquid containing an alkaline earth metal such as strontium. The amount of the adsorbent added to the waste liquid is preferably such that the total amount of water-soluble metals contained in the adsorbent is 10 equivalents or more with respect to metal atoms such as strontium contained in the waste liquid. The amount is more preferably equivalent or more, and most preferably 1000 equivalent or more. The upper limit of the amount added is not particularly required, but practically it is about 50 g per liter of waste liquid. After the adsorbent is added, the mixture is sufficiently stirred and left for 1 hour or longer, more preferably left for 5 hours or longer, and most preferably left for 24 hours or longer.

  The adsorbent having adsorbed the metal atoms can be removed from the waste liquid by a method such as filtration or decantation, but can be rapidly aggregated and solidified by adding a flocculant. As the flocculant, those used in the method of the present invention are preferably used, and the amount and method of use thereof may be the same as those described above.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Example 1
To 40 mL of an aqueous solution containing 6.5 ppm strontium chloride, 2 g of 1 M barium chloride aqueous solution, 4 g of 0.6 M disodium hydrogenphosphate aqueous solution and 8 g of 100 g / L sodium tripolyphosphate aqueous solution were added instantaneously. An off-white precipitate formed. Each aqueous solution was temperature-controlled at 60 ° C. and tested. The solution was sufficiently stirred and then allowed to stand at room temperature for 10 hours to separate the supernatant. When strontium contained in the supernatant was quantified by ICP-AES, 95% of strontium was removed.

Example 2
To 40 mL of an aqueous solution containing 6.5 ppm strontium chloride, 2 g of 1 M barium chloride aqueous solution, 4 g of 0.6 M disodium hydrogenphosphate aqueous solution and 8 g of 100 g / L sodium tripolyphosphate aqueous solution were added instantaneously. An off-white precipitate formed. Each aqueous solution was temperature-controlled at 60 ° C. and tested.

  To this dispersion, 2 g of polyaluminum chloride aqueous solution (10% by mass) at room temperature, 0.01 g of cationic polymer flocculant (Uniflocca UF-340, polymethacrylate molecular weight of about 3.1 million, Unitika Ltd.) ), 0.01 g of anionic polymer flocculant (Uniflocca UF-105, polyacrylamide molecular weight approx. 13 million, manufactured by Unitika Ltd.), stirred for 30 minutes and allowed to stand for 3 hours, solidifying into a stone shape The precipitate was separated into a supernatant. The supernatant was filtered through a 100 μmφ membrane filter to remove the precipitate. When strontium contained in the filtered water was quantified by ICP-AES, 96% of strontium was removed.

Comparative Example 1
To 40 mL of an aqueous solution containing 10 ppm strontium chloride, add 2 g of 1 M calcium nitrate aqueous solution, 4 g of 0.6 M disodium hydrogenphosphate aqueous solution, and 8 g of 100 g / L sodium tripolyphosphate aqueous solution. Of precipitate formed. Each aqueous solution was temperature-controlled at 60 ° C. and tested. This solution was allowed to stand at room temperature for 10 hours, and the supernatant was separated. When strontium contained in the supernatant was quantified by ICP-AES, strontium was hardly removed.

Example 3
(1) Adsorbent composed of phosphate compound and barium
While stirring 4 g of 1 M barium chloride, 4 g of 0.6 M aqueous solution of disodium hydrogenphosphate and 8 g of 100 g / L aqueous solution of sodium tripolyphosphate were sequentially added, and a white precipitate was formed. The supernatant was removed by decantation to obtain an adsorbent composed of a phosphate compound and barium.

(2) Strontium adsorption removal test
Add 4 g of the adsorbent to 40 mL of 6.5 ppm strontium chloride aqueous solution and stir for 2 hours. Then add 1 g of sulfuric acid band aqueous solution (10% by mass) and 0.3 g of polyethyleneimine aqueous solution (30% by mass). The mixture was stirred for 30 minutes, further added with 2 g of a sodium polyacrylate aqueous solution (0.3% by mass), stirred for 30 minutes, and allowed to stand for 3 hours to separate into a solidified precipitate and a supernatant. The supernatant was filtered through a 100 μmφ membrane filter to remove the precipitate. When strontium contained in the aqueous solution after filtration was quantified by ICP-AES, 95% or more of strontium was removed.

Claims (10)

A waste liquid treatment method for removing and recovering metal atoms in a waste liquid, the waste liquid,
(a) a phosphate compound;
(b) having a step of adding a water-soluble metal salt containing at least one metal selected from the group consisting of potassium, rubidium, cesium, strontium, barium, iron, cobalt, nickel, copper and zinc. Characteristic processing method.   The waste liquid treatment method according to claim 1, further comprising a step of adding a flocculant after the addition step.   3. The treatment method according to claim 1, wherein the phosphoric acid compound and the water-soluble metal salt are added to the waste liquid heated to 50 to 80 ° C. 4.   The waste liquid treatment method according to any one of claims 1 to 3, wherein the phosphoric acid compound comprises phosphate, hydrogen phosphate, pyrophosphate, tripolyphosphate, tetrapolyphosphate, and metaphosphate. The processing method characterized by including at least 1 sort (s) chosen from.   5. The waste liquid treatment method according to claim 1, wherein the water-soluble metal salt is at least one selected from the group consisting of halides, nitrates, and sulfates of the metal. Processing method.   The waste liquid treatment method according to claim 1, wherein the flocculant is an inorganic flocculant and / or an organic polymer flocculant.   The waste liquid treatment method according to claim 6, wherein the inorganic flocculant is at least one selected from the group consisting of aluminum sulfate, aluminum chloride, polyaluminum chloride, ferric chloride, and polyferric sulfate. Characteristic processing method.   The waste liquid treatment method according to claim 6 or 7, wherein the organic polymer flocculant is a cationic organic polymer flocculant, an anionic organic polymer flocculant, a nonionic organic polymer flocculant, an amphoteric organic polymer flocculant. A processing method characterized by being at least one selected from the group consisting of molecular flocculants.   The waste liquid treatment method according to any one of claims 2 to 8, wherein the step of adding the flocculant further adds the polymer flocculant after the inorganic flocculant and / or the polymer flocculant is added and mixed. A processing method comprising a step of adding and mixing.   An adsorbent for adsorbing metal atoms in a waste liquid comprising a phosphate compound and an alkali metal, alkaline earth metal or transition metal.