JP5277559B2 - Method and apparatus for recovering phosphoric acid from phosphoric acid-containing water - Google Patents

Method and apparatus for recovering phosphoric acid from phosphoric acid-containing water Download PDF

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JP5277559B2
JP5277559B2 JP2007093943A JP2007093943A JP5277559B2 JP 5277559 B2 JP5277559 B2 JP 5277559B2 JP 2007093943 A JP2007093943 A JP 2007093943A JP 2007093943 A JP2007093943 A JP 2007093943A JP 5277559 B2 JP5277559 B2 JP 5277559B2
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phosphoric acid
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JP2008246442A (en
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信博 織田
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Kurita Water Industries Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
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    • Y02A20/124—Water desalination
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis

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Description

本発明は、リン酸含有水から逆浸透装置によりリン酸を回収する方法および装置に関し、特に液晶基板やウエハーその他の電子機器をエッチングした後のリン酸を含有する洗浄排水からリン酸などの有価物と処理水である純水の回収に適したリン酸を回収する方法および装置に関するものである。   TECHNICAL FIELD The present invention relates to a method and apparatus for recovering phosphoric acid from phosphoric acid-containing water using a reverse osmosis device, and in particular, from waste water containing phosphoric acid after etching a liquid crystal substrate, a wafer, or other electronic equipment, such as phosphoric acid. The present invention relates to a method and an apparatus for recovering phosphoric acid suitable for recovery of waste water and treated water.

液晶基板やウエハーその他の電子機器のエッチングには、リン酸を含むエッチング液が用いられている。エッチング工程で発生する高濃度の廃エッチング液は回収して再生利用されているが、エッチング後の電子機器は純水により洗浄され、低濃度の洗浄排水が大量に生成する。このような洗浄排水はエッチング液の成分であるリン酸、硝酸、酢酸、その他の酸成分等のほか、エッチングによって溶出した金属イオンその他の不純物が含まれているが、大部分は純水である。   An etching solution containing phosphoric acid is used for etching liquid crystal substrates, wafers, and other electronic devices. The high-concentration waste etchant generated in the etching process is recovered and recycled, but the electronic equipment after etching is washed with pure water, and a large amount of low-concentration washing wastewater is generated. Such washing wastewater contains phosphoric acid, nitric acid, acetic acid, other acid components, etc., which are components of the etching solution, as well as metal ions and other impurities that are eluted by etching, but most are pure water. .

このようなエッチング洗浄排水は、従来は他の排水と混合して処理されている。一般的なリン酸やフッ酸を含む排水の処理技術としては、凝集沈殿処理が挙げられる。しかしリン酸やフッ酸の凝集沈澱処理を行う場合、多量の薬剤使用と多量の汚泥発生による処理コストの上昇、環境への負荷の増大などが問題となる。加えて、凝集沈殿処理で多量に添加する薬剤による水溶性イオンの増加が、水回収するに当たり、逆浸透膜プロセスの操作圧力上昇による動力コストの増大、処理水質の悪化、スケールの発生、また、イオン交換法では再生剤使用量の増加につながっている。 Such etching cleaning wastewater is conventionally treated by mixing with other wastewater. As a general treatment technique for wastewater containing phosphoric acid or hydrofluoric acid, coagulation sedimentation treatment can be mentioned. However, when coagulating and precipitating with phosphoric acid or hydrofluoric acid , there are problems such as an increase in processing cost due to the use of a large amount of chemicals and the generation of a large amount of sludge, and an increase in environmental burden. In addition, increase of the water-soluble ions by a large amount of drug added in the coagulation-sedimentation process, upon water recovery, increase of the dynamic power costs due to the operation pressure rise of the reverse osmosis membrane process, deterioration of the treated water, the scale of the occurrence, also The ion exchange method has led to an increase in the amount of regenerant used.

特許文献１（特開２００６−７５８２０号）には、イオン交換樹脂でリン酸、硝酸などのイオンを除去し、純水およびリン酸塩の回収が行われている。しかし、この方法ではリン酸塩（リン酸二水素ナトリウムなど）として回収しているが、リン酸塩の販路が殆どなく、リン酸のナトリウム塩は溶解度が小さいため、液状ではリン酸の含有率が低く、運搬は困難であり、カリウム塩とするには苛性カリが高価である。またリン酸二水素ナトリウムにするためにＨ形カチオン樹脂に通液する方法が示されているが、カチオン樹脂の再生で塩酸などの酸が消費され、アニオン樹脂の再生で使用した水酸化ナトリウムも無駄に排出されるなどの欠点があった。
特開２００６−７５８２０号 In Patent Document 1 (Japanese Patent Laid-Open No. 2006-75820), ions such as phosphoric acid and nitric acid are removed with an ion exchange resin, and pure water and phosphate are recovered. However, in this method, it is recovered as a phosphate (sodium dihydrogen phosphate, etc.). However, since there is almost no sales channel for phosphate, and the sodium salt of phosphoric acid has low solubility, the content of phosphoric acid in liquid form The caustic potash is expensive to make potassium salt. In addition, a method of passing through an H-type cation resin to make sodium dihydrogen phosphate is shown, but acid such as hydrochloric acid is consumed by regeneration of the cation resin, and sodium hydroxide used for regeneration of the anion resin is also used. There were drawbacks such as wasted waste.
JP 2006-75820 A

本発明の課題は、簡単な構成と操作により、高濃度の液状で運搬可能であり、回収物として有用な高純度のリン酸を、リン酸含有水から低コストで、かつ効率よく回収できるリン酸を回収する方法および装置を提案することである。   It is an object of the present invention to provide a high-concentration liquid phosphoric acid that can be transported in a high-concentration liquid state with a simple structure and operation, and that can be efficiently recovered from phosphoric acid-containing water at a low cost. It is to propose a method and apparatus for recovering acid.

本発明は、次のリン酸イオン含有水からリン酸を回収する方法および装置である。
（１） カチオンを除去したリン酸含有水からリン酸を回収する方法であって、
カチオンを除去したリン酸含有水をｐＨ３以下、かつリン酸濃度１〜１５重量％の条件下で逆浸透装置に供給して膜分離処理を行い、リン酸以外の酸を水とともに透過液室側に透過させて、リン酸を濃縮液室側に濃縮し、リン酸濃縮液を回収することを特徴とするリン酸の回収方法。
（２） 濃縮液室の濃縮液を取出して濃縮液室へ循環する過程を有し、循環する濃縮液にカチオンを除去した被処理リン酸含有水を加えて逆浸透処理を行う上記（１）記載の方法。
（３） 濃縮液室の濃縮液を取出して濃縮液室へ循環する過程を有し、循環する濃縮液に希釈水を加えて膜分離処理を行う上記（１）または（２）記載の方法。
（４） カチオンを除去したリン酸含有水を逆浸透装置に供給する前に、前処理としてカチオンおよびアニオンを含む不純物の除去を行う上記（１）ないし（３）のいずれかに記載の方法。
（５） 逆浸透装置の透過水から酸を含む不純物を除去して純水を回収する上記（１）ないし（４）のいずれかに記載の方法。
（６） 不純物の除去を、電気再生式イオン交換装置により行う上記（５）記載の方法。
（７） リン酸濃縮液を蒸発濃縮して、水とともに揮発性成分を除去して濃縮する上記（１）ないし（６）のいずれかに記載の方法。
（８） 希釈水が透過水から不純物を除去した純水である上記（３）記載の方法。
（９） カチオンを除去したリン酸含有水からリン酸を回収する装置であって、
カチオンを除去したリン酸含有水をｐＨ３以下、かつリン酸濃度１〜１５重量％の条件下で膜分離処理して、リン酸以外の酸を水とともに透過液室側に透過させ、リン酸を濃縮液室側に濃縮する逆浸透装置と、
カチオンを除去したリン酸含有水をｐＨ３以下、かつリン酸濃度１〜１５重量％の条件下で逆浸透装置の濃縮液室側に供給するリン酸含有水供給部と、
逆浸透装置の透過液室側から透過液を取出す透過液取出部と、
逆浸透装置の濃縮液室側から濃縮リン酸液を取出す濃縮リン酸液取出部と、
濃縮リン酸液取出部から取出した濃縮リン酸液を濃縮液室側に循環する循環経路と
を有することを特徴とするリン酸回収装置。
（１０） 循環経路を循環する濃縮液に希釈水を加える希釈水供給部を有する上記（９）記載の装置。
（１１） カチオンおよびアニオンを含む不純物の除去を行う前処理装置を原水供給部に有する上記（９）または（１０）記載の装置。
（１２） 逆浸透装置の透過水から酸を含む不純物を除去する不純物除去装置を有する上記（９）ないし（１１）のいずれかに記載の装置。
（１３） 不純物除去装置が電気再生式イオン交換装置である上記（１２）記載の装置。
（１４） リン酸濃縮液を蒸発濃縮して、水とともに揮発性成分を除去して濃縮する蒸発濃縮装置を有する上記（９）ないし（１３）のいずれかに記載の装置。 The present invention is a method and apparatus for recovering phosphoric acid from the following phosphate ion-containing water.
(1) A method for recovering phosphoric acid from phosphoric acid-containing water from which cations have been removed ,
Phosphoric acid-containing water from which cations have been removed is supplied to a reverse osmosis device under conditions of pH 3 or lower and a phosphoric acid concentration of 1 to 15% by weight, and membrane separation treatment is performed. A method of recovering phosphoric acid, characterized in that the phosphoric acid is concentrated on the side of the concentrate chamber, and the phosphoric acid concentrate is recovered.
(2) The above-mentioned (1), which has a process of taking out the concentrate in the concentrate chamber and circulating it to the concentrate chamber, and adding the treated phosphoric acid-containing water from which cations have been removed to the circulating concentrate. The method described.
(3) The method according to (1) or (2) above, wherein the method comprises the step of taking out the concentrate from the concentrate chamber and circulating it to the concentrate chamber, and performing membrane separation treatment by adding dilution water to the circulating concentrate.
(4) before being supplied to the reverse osmosis device phosphoric acid-containing water to remove cations, according to any one of (1) to effect removal of impurities including cationic and A anions (3) as a pre-treatment the method of.
(5) The method according to any one of (1) to (4) above, wherein pure water is recovered by removing impurities including acid from the permeated water of the reverse osmosis device.
(6) The method according to (5) above, wherein the impurities are removed by an electric regenerative ion exchange apparatus.
(7) The method according to any one of (1) to (6) above, wherein the phosphoric acid concentrate is concentrated by evaporation to remove volatile components together with water.
(8) The method according to (3) above, wherein the dilution water is pure water obtained by removing impurities from the permeated water.
(9) An apparatus for recovering phosphoric acid from phosphoric acid-containing water from which cations have been removed ,
Phosphoric acid-containing water from which cations have been removed is subjected to a membrane separation treatment under conditions of pH 3 or lower and a phosphoric acid concentration of 1 to 15% by weight, and an acid other than phosphoric acid is allowed to permeate to the permeate chamber side together with water. A reverse osmosis device for concentrating to the concentrate chamber side;
A phosphoric acid-containing water supply unit that supplies phosphoric acid-containing water from which cations have been removed to the concentrated liquid chamber side of the reverse osmosis device under conditions of pH 3 or lower and a phosphoric acid concentration of 1 to 15% by weight;
A permeate extractor for extracting permeate from the permeate chamber side of the reverse osmosis device;
A concentrated phosphoric acid solution extraction section for extracting the concentrated phosphoric acid solution from the concentrated liquid chamber side of the reverse osmosis device ;
And a circulation path for circulating the concentrated phosphoric acid solution extracted from the concentrated phosphoric acid solution extraction unit to the concentrated liquid chamber side.
(10) The apparatus according to (9), further including a dilution water supply unit that adds dilution water to the concentrate circulating in the circulation path.
(11) (9) having a processor before the removal of impurities, including cations and A anions in the raw water supply unit or (10) apparatus as claimed.
(12) The device according to any one of (9) to (11), further including an impurity removing device that removes impurities including acid from the permeated water of the reverse osmosis device.
(13) The apparatus according to (12), wherein the impurity removing device is an electric regenerative ion exchange device.
(14) The apparatus according to any one of the above (9) to (13), further comprising an evaporation concentrator that evaporates and concentrates the phosphoric acid concentrate and removes volatile components together with water to concentrate.

本発明において、処理の対象となるカチオンを除去したリン酸含有水は、リン酸を含有する水であれば制限なく対象とすることができるが、リン酸イオン５０〜１００００ｍｇ／Ｌ、特に５０〜２０００ｍｇ／Ｌ含有し、ｐＨは３以下、特に２．８以下であって、いずれの場合も１以上、特に１．８以上である酸性水が処理対象として好ましく、リン酸イオンのほかに、硝酸イオン、酢酸イオン等の酸成分、その他のアニオン、ならびにその他の不純物が含まれていてもよいが、金属イオン等のカチオンを除去したリン酸含有水を処理の対象とする。本発明では特に硝酸イオン、酢酸イオン等の他の酸成分を含むリン酸含有水から、硝酸イオン、酢酸イオン等の他の酸成分を除去して、純度の高いリン酸を回収するのに適している。 In the present invention, the phosphoric acid-containing water from which the cations to be treated are removed can be used without limitation as long as it contains phosphoric acid, but phosphate ions are 50 to 10,000 mg / L, particularly 50 to Acidic water containing 2000 mg / L and having a pH of 3 or less, particularly 2.8 or less, and in any case 1 or more, particularly 1.8 or more is preferable as the treatment target. ions, acid components such as acetic acid ion, and other anionic, but may contain other impurities arrangement Niso, to be processed phosphoric acid containing water to remove cations such as metal ions. In the present invention, it is particularly suitable for recovering highly pure phosphoric acid by removing other acid components such as nitrate ion and acetate ion from phosphoric acid-containing water containing other acid components such as nitrate ion and acetate ion. ing.

特に処理対象として好ましいリン酸含有水は、液晶基板やウエハーその他の電子機器のリン酸含有エッチング液によるエッチング後に、純水洗浄を行う際に発生する低濃度の洗浄排水がある。このようなエッチング後の洗浄排水の例としては、リン酸イオン５０〜２０００ｍｇ／Ｌ、硝酸イオン１０〜５００ｍｇ／Ｌ、酢酸イオン５〜３００ｍｇ／Ｌを含有し、ｐＨ１．８〜２．８の酸性水がある。   Particularly preferable phosphoric acid-containing water as a treatment target is low-concentration cleaning wastewater generated when pure water cleaning is performed after etching with a phosphoric acid-containing etching solution for liquid crystal substrates, wafers, and other electronic devices. Examples of such cleaning waste water after etching include phosphate ions 50 to 2000 mg / L, nitrate ions 10 to 500 mg / L, acetate ions 5 to 300 mg / L, and an acidity of pH 1.8 to 2.8. There is water.

本発明では、カチオンを除去したリン酸含有水からリン酸を回収するために、カチオンを除去したリン酸含有水をｐＨ３以下、かつリン酸濃度１〜１５重量％の条件下で逆浸透装置に供給して膜分離処理を行うが、カチオンを除去したリン酸含有水を逆浸透装置に供給する前に、前処理としてカチオンおよびアニオンを含む不純物の除去を行うのが好ましい。この場合、沈殿分離、濾過等による固形物の除去、ならびにカチオン交換樹脂による金属イオン等のカチオンの除去、ならびにアニオン交換樹脂による過塩素酸、有機酸錯体等のアニオンの除去などを行うことができる。このような前処理工程に用いる前処理装置としては、上記目的に採用されている一般的な装置が用いられる。 In the present invention, in order to recover phosphoric acid from phosphoric acid-containing water from which cations have been removed, phosphoric acid-containing water from which cations have been removed is supplied to a reverse osmosis device under conditions of pH 3 or lower and a phosphoric acid concentration of 1 to 15% by weight. Although for supplying to membrane separation processes, before supplying phosphate-containing water to remove cations reverse osmosis apparatus, to carry out the removal of impurities, including cations and a anion as a pretreatment preferable. In this case, precipitation separation, removal of solids by filtration, etc., removal of cations such as metal ions by cation exchange resin, and removal of anions such as perchloric acid and organic acid complexes by anion exchange resin can be performed. . As a pretreatment apparatus used for such a pretreatment step, a general apparatus employed for the above purpose is used.

エッチング後の洗浄排水に含まれるインジウム、鉄、アルミニウム等の金属イオンは膜分離工程における逆浸透（ＲＯ）膜の目詰まりの原因となり、過塩素酸などは高濃度になると膜損傷の原因となるので、これらのカチオンやアニオンを除去することにより、膜の目詰まりや損傷などが防止できるので好ましい。カチオン交換樹脂としては、強酸性または弱酸性カチオン交換樹脂を用いることができるが、Ｈ形の強酸性カチオン交換樹脂を用いてこれらのカチオンを交換除去すると、処理液は酸成分が増加してｐＨ３以下に調整することが容易になるので好ましい。カチオン交換樹脂としてはキレート樹脂でもよい。アニオン交換樹脂としては、強塩基性または弱塩基性アニオン交換樹脂を用いることができる。アニオン交換樹脂はリン酸形等の酸形で用い、リン酸、硝酸、酢酸等を素通りさせ、他の不純物アニオンを除去する。   Metal ions such as indium, iron, and aluminum contained in the cleaning waste water after etching cause clogging of the reverse osmosis (RO) membrane in the membrane separation process, and perchloric acid and the like cause membrane damage at high concentrations. Therefore, it is preferable to remove these cations and anions because clogging or damage of the membrane can be prevented. As the cation exchange resin, a strong acid or weak acid cation exchange resin can be used. However, when these cations are exchanged and removed using an H-form strong acid cation exchange resin, the treatment liquid has an increased acid component, resulting in a pH of 3 Since adjustment to the following becomes easy, it is preferable. The cation exchange resin may be a chelate resin. As the anion exchange resin, a strongly basic or weakly basic anion exchange resin can be used. The anion exchange resin is used in an acid form such as a phosphoric acid form, and passes through phosphoric acid, nitric acid, acetic acid and the like to remove other impurity anions.

本発明で膜分離工程における逆浸透装置は、ＲＯ装置とも呼ばれ、逆浸透（ＲＯ）膜により透過液室と濃縮液室とに区画され、リン酸含有水をｐＨ３以下、かつリン酸濃度１〜１５重量％の条件下で濃縮液室側に供給して逆浸透処理を行い、リン酸以外の酸を水とともに透過液室側に透過させるとともに、リン酸を濃縮液室側に濃縮させるように構成される。逆浸透装置の濃縮液室側には、リン酸含有水を供給するリン酸含有水供給部、ならびに濃縮リン酸液を取出す濃縮リン酸液取出部が形成される。逆浸透装置の透過液室側には、透過液を取出す透過液取出部が形成される。濃縮リン酸液取出部とリン酸含有水供給部間には、濃縮リン酸液取出部から取出した濃縮リン酸液を濃縮液室側に循環する循環経路が形成される。逆浸透膜は、浸透圧により水を透過させ、あるいは逆に浸透圧よりも高圧に加圧して被処理液を供給して逆浸透により水を透過させ、一方塩分、その他の溶質を透過させないで阻止する半透膜である。   In the present invention, the reverse osmosis device in the membrane separation step is also called an RO device, and is divided into a permeate chamber and a concentrate chamber by a reverse osmosis (RO) membrane, and the phosphoric acid-containing water has a pH of 3 or less and a phosphoric acid concentration of 1 Reverse osmosis treatment is performed by supplying to the concentrate chamber side under a condition of ˜15% by weight so that an acid other than phosphoric acid is permeated to the permeate chamber side together with water, and phosphoric acid is concentrated to the concentrate chamber side. Configured. On the concentrated liquid chamber side of the reverse osmosis device, a phosphoric acid-containing water supply unit that supplies phosphoric acid-containing water and a concentrated phosphoric acid solution extraction unit that extracts the concentrated phosphoric acid solution are formed. On the permeate chamber side of the reverse osmosis device, a permeate extractor for taking out the permeate is formed. A circulation path for circulating the concentrated phosphoric acid solution extracted from the concentrated phosphoric acid solution extracting unit to the concentrated solution chamber side is formed between the concentrated phosphoric acid solution extracting unit and the phosphoric acid-containing water supply unit. Reverse osmosis membranes allow water to permeate by osmotic pressure, or conversely, pressurize to a pressure higher than osmotic pressure and supply the liquid to be treated to allow water to permeate by reverse osmosis, while not allowing salt and other solutes to permeate. A semi-permeable membrane to block.

逆浸透膜の材質としては、上記の特性を有する限り特に制限されず、例えばポリアミド系透過膜、ポリイミド系透過膜、セルロース系透過膜などが挙げられ、非対称逆浸透膜でもよいが、微多孔性支持体上に実質的に選択分離性を有する活性なスキン層を形成した複合逆浸透膜が好ましい。逆浸透装置はこのような逆浸透膜を備えるものであればよいが、逆浸透膜と支持機構、集水機構等が一体化した膜モジュールを備えるものが好ましい。膜モジュールとしては特に制限はなく、例えば管状膜モジュール、平面膜モジュール、スパイラル膜モジュール、中空糸膜モジュールなどを挙げることができる。これらを備える逆浸透装置としては公知のものが使用でき、低圧で操作される高透過性のものが好ましい。   The material of the reverse osmosis membrane is not particularly limited as long as it has the above characteristics, and examples thereof include a polyamide-based permeable membrane, a polyimide-based permeable membrane, and a cellulose-based permeable membrane. A composite reverse osmosis membrane in which an active skin layer having substantially selective separability is formed on a support is preferred. The reverse osmosis device may be any device that includes such a reverse osmosis membrane, but preferably includes a membrane module in which a reverse osmosis membrane, a support mechanism, a water collection mechanism, and the like are integrated. There is no restriction | limiting in particular as a membrane module, For example, a tubular membrane module, a plane membrane module, a spiral membrane module, a hollow fiber membrane module etc. can be mentioned. As the reverse osmosis apparatus provided with these, a known apparatus can be used, and a highly permeable apparatus operated at a low pressure is preferable.

本発明では膜分離工程において、カチオンを除去したリン酸含有水をｐＨ３以下かつリン酸濃度１〜１５重量％、好ましくは２〜１０重量％の条件下で逆浸透装置に供給して膜分離（逆浸透）処理を行う。リン酸含有水がｐＨ３以下の状態で得られる場合には、そのままｐＨ調整することなく逆浸透装置に供給することができるが、必要により塩酸、硝酸等のｐＨ調整剤の添加によりｐＨ調整してもよい。前処理においてカチオン交換樹脂により金属イオン等のカチオンの除去を行うことによりｐＨ３以下に調整される場合も同様である。液晶基板やウエハー等のエッチング後の洗浄排水は、通常ｐＨ３以下の状態で得られるので、ｐＨ調整することなく逆浸透装置に供給することができ、ｐＨ調整する場合でもｐＨ調整剤の添加量は少なくなる。 In the present invention, in the membrane separation step, phosphoric acid-containing water from which cations have been removed is supplied to a reverse osmosis apparatus under conditions of pH 3 or lower and phosphoric acid concentration of 1 to 15% by weight, preferably 2 to 10% by weight. Reverse osmosis) treatment. When the phosphoric acid-containing water is obtained in a state of pH 3 or lower, it can be supplied to the reverse osmosis apparatus without adjusting the pH as it is, but if necessary, the pH can be adjusted by adding a pH adjusting agent such as hydrochloric acid or nitric acid. Also good. The same applies when the pH is adjusted to 3 or less by removing cations such as metal ions with a cation exchange resin in the pretreatment. Since cleaning wastewater after etching of liquid crystal substrates and wafers is usually obtained in a state of pH 3 or lower, it can be supplied to a reverse osmosis device without adjusting pH, and even when adjusting pH, the amount of pH adjuster added is Less.

カチオンを除去したリン酸含有水がリン酸濃度１〜１５重量％で得られる場合は、そのまま膜分離処理を行って逆浸透による分離を行うことができるが、リン酸濃度１重量％未満の場合は、循環経路を通して濃縮液を循環しながら膜分離処理を行うことにより、リン酸濃度１重量％以上に濃縮することができる。この場合、低濃度のリン酸含有水を循環しながら濃縮し、リン酸濃度１重量％以上に濃縮された時点で循環液を入れ替える回分式の処理を行ってもよいが、リン酸濃度１〜１５重量％に濃縮された濃縮液を循環しながら、循環する濃縮液に低濃度の被処理リン酸含有水を加え、濃縮液を一部ずつリン酸濃縮液として取出すと、見掛け上一過式の処理が行えるので好ましい。濃縮液室の濃縮液を取出して濃縮液室へ循環する過程において、循環する濃縮液に希釈水を加えて逆浸透処理を行うことにより、リン酸以外の酸の除去率を高めることができる。希釈水としては透過水から不純物を除去した回収水を使用することができる。 When the phosphoric acid-containing water from which cations have been removed is obtained at a phosphoric acid concentration of 1 to 15% by weight, it can be separated by reverse osmosis as it is, but when the phosphoric acid concentration is less than 1% by weight. Can be concentrated to a phosphoric acid concentration of 1% by weight or more by performing membrane separation treatment while circulating the concentrate through the circulation path. In this case, concentration may be performed while circulating low-concentration phosphoric acid-containing water, and when the phosphoric acid concentration is concentrated to 1% by weight or more, a batch process may be performed in which the circulating fluid is replaced. While circulating the concentrated solution concentrated to 15% by weight, adding low-concentration treated phosphoric acid-containing water to the circulating concentrated solution and taking out the concentrated solution partly as a phosphoric acid concentrated solution, apparently transient This is preferable because the above process can be performed. In the process of taking out the concentrate in the concentrate chamber and circulating it to the concentrate chamber, the removal rate of acids other than phosphoric acid can be increased by adding dilution water to the circulating concentrate and performing reverse osmosis treatment. As the dilution water, recovered water obtained by removing impurities from the permeated water can be used.

カチオンを除去したリン酸含有水をｐＨ３以下の条件下で逆浸透装置に供給して膜分離処理を行うと、硝酸、酢酸等のリン酸以外の酸は、水とともに逆浸透膜を透過して透過液室側に移行し、透過液室側から取出される。リン酸は逆浸透膜の透過を阻止され、濃縮液室側に残留して濃縮されるので、濃縮液室側からリン酸濃縮液として回収することができる。このとき少量のリン酸以外の酸が濃縮液に残留するが、リン酸濃度１〜１５重量％の条件下で膜分離処理を行うと、リン酸以外の酸の阻止率が低くなり、透過率が高くなるので、高純度のリン酸濃縮液を回収することができる。逆浸透装置に供給するリン酸含有水の圧力は０．３〜５ＭＰａ、好ましくは０．５〜３ＭＰａとすることができる。 When water containing phosphonic acid containing cations is supplied to a reverse osmosis device under a pH of 3 or less and membrane separation treatment is performed, acids other than phosphoric acid such as nitric acid and acetic acid permeate through the reverse osmosis membrane together with water. It moves to the permeate chamber side and is taken out from the permeate chamber side. Since phosphoric acid is prevented from permeating through the reverse osmosis membrane and remains on the concentrate chamber side to be concentrated, it can be recovered from the concentrate chamber side as a phosphoric acid concentrate. At this time, a small amount of acid other than phosphoric acid remains in the concentrated solution. However, when membrane separation treatment is performed under conditions of phosphoric acid concentration of 1 to 15% by weight, the blocking rate of acids other than phosphoric acid is lowered, and the transmittance Therefore, a high-purity phosphoric acid concentrate can be recovered. The pressure of the phosphoric acid containing water supplied to a reverse osmosis apparatus can be 0.3-5 Mpa, Preferably it can be 0.5-3 Mpa.

逆浸透膜の透過においてイオン性物質と非イオン性物質の透過を比較すると、逆浸透膜阻止率は、同じ程度の分子量であっても、非イオン性物質に比べてイオン性物質の方が圧倒的に阻止されやすいと言われている。しかし本発明者等が研究を重ねた結果、このような常識とは異なり、リン酸が解離しにくいｐＨ３以下の条件下で逆浸透膜処理すると、リン酸の阻止率は硝酸や酢酸よりも圧倒的に高くなり、硝酸や酢酸等のリン酸以外の酸とリン酸とを分別して回収できることが分かった。低ｐＨ下でリン酸が逆浸透膜に強く阻止される理由は、リン酸が重合リン酸の形態となって分子量が大きくなり、阻止率がアップしたためであると推測される。 Comparing the permeation of ionic and nonionic substances in the permeation of reverse osmosis membranes, even if the reverse osmosis membrane blocking rate is the same molecular weight, ionic substances are overwhelming compared to nonionic substances. It is said that it is easy to be blocked. However, as a result of repeated research by the present inventors, unlike such common sense, when a reverse osmosis membrane treatment is performed under a pH of 3 or less where phosphoric acid is difficult to dissociate, the rejection rate of phosphoric acid is overwhelmingly higher than that of nitric acid or acetic acid. Thus, it was found that acids other than phosphoric acid, such as nitric acid and acetic acid, and phosphoric acid can be separated and recovered. Reason phosphoric acid at low pH is strongly blocked by the reverse osmosis membrane, phosphate molecular weight increases becomes the form of Polymerization phosphate, rejection is presumed to be because the up.

ｐＨ３以下の条件下での硝酸、酢酸等のリン酸以外の酸の阻止率は低く、通常のリン酸含有エッチング液を膜処理する場合の阻止率は１％以下であるが、リン酸濃度が高いほどリン酸以外の酸の阻止率は低くなり、リン酸濃度１重量％以上ではリン酸以外の酸の阻止率がマイナスになる。ここで阻止率とは、逆浸透膜が溶質の透過を阻止する割合であり、次の式（１）で示される。   The blocking rate of acids other than phosphoric acid such as nitric acid and acetic acid under pH 3 or lower is low, and the blocking rate when a normal phosphoric acid-containing etching solution is processed is 1% or less. The higher the acid blocking rate, the lower the blocking rate of acids other than phosphoric acid. When the phosphoric acid concentration is 1% by weight or more, the blocking rate of acids other than phosphoric acid becomes negative. Here, the blocking rate is a rate at which the reverse osmosis membrane blocks the permeation of the solute, and is represented by the following formula (1).

阻止率（％）＝〔１−Ｃ３／（Ｃ１・Ｃ２）１／２〕×１００ ・・・（１）
（式（１）中、Ｃ１は供給液入口の溶質濃度、Ｃ２は濃縮液出口の溶質濃度、Ｃ３は透過液の溶質濃度である。）
式（１）において、（（Ｃ１・Ｃ２）１／２）は相乗平均を示し、（Ｃ３／（Ｃ１・Ｃ２）１／２）は濃縮液の溶質の（相乗）平均濃度に対する透過液の溶質濃度の比を示す。このため阻止率が低いほど、溶質が透過液側に透過することを示している。通常の観念では阻止率がマイナスになることはないと認識されやすいが、式（１）では式の構成から阻止率がマイナスになることがあり、この場合、濃縮液の溶質濃度よりも透過液の溶質濃度が高く、溶質が高透過率で透過することを示している。 Blocking rate (%) = [1-C 3 / (C 1 · C 2 ) 1/2 ] × 100 (1)
(In formula (1), C 1 is the solute concentration at the inlet of the supply liquid, C 2 is the solute concentration at the outlet of the concentrate, and C 3 is the solute concentration of the permeate.)
In formula (1), ((C 1 · C 2 ) 1/2 ) represents the geometric mean, and (C 3 / (C 1 · C 2 ) 1/2 ) is the (synergistic) average concentration of the solute in the concentrate. Shows the ratio of the solute concentration of the permeate to. For this reason, it has shown that a solute permeate | transmits to the permeate side, so that the rejection rate is low. Although it is easy to recognize that the rejection rate is not negative in the normal concept, the rejection rate may be negative due to the structure of the equation (1). In this case, the permeated liquid is higher than the solute concentration of the concentrate. This indicates that the solute concentration is high and the solute permeates at high transmittance.

リン酸濃度１重量％以上でリン酸以外の酸の阻止率がマイナスになるということは、リン酸濃度１重量％以上、特に２重量％以上では濃縮液中に残留するリン酸以外の酸濃度は低くなり、純度の高いリン酸濃縮液が得られることを意味する。濃縮液のリン酸濃度が高過ぎると浸透圧の関係で膜処理が行えなくなるので、濃縮液のリン酸濃度の上限は１５重量％、好ましくは１０重量％とされる。このようなリン酸濃度の濃縮液を循環しながら、循環する濃縮液に被処理リン酸含有水を加え、濃縮液を一部ずつリン酸濃縮液として取出して一過式の処理を行うと、上記リン酸濃度を維持して効率よく処理を行うことができる。   When the phosphoric acid concentration is 1% by weight or more, the rejection rate of acids other than phosphoric acid is negative. When the phosphoric acid concentration is 1% by weight or more, particularly 2% by weight or more, the concentration of acids other than phosphoric acid remaining in the concentrated liquid Means that a highly concentrated phosphoric acid concentrate is obtained. If the concentration of phosphoric acid in the concentrate is too high, membrane treatment cannot be performed due to osmotic pressure, so the upper limit of the concentration of phosphoric acid in the concentrate is 15% by weight, preferably 10% by weight. While circulating the concentrated solution of such phosphoric acid concentration, adding the water to be treated containing phosphoric acid to the circulating concentrated solution, taking out the concentrated solution partly as a phosphoric acid concentrated solution, and performing a transient treatment, It is possible to efficiently perform the treatment while maintaining the phosphoric acid concentration.

濃縮液を循環しながら膜処理が行う際、濃縮液の循環回数を多くするほど、リン酸以外の酸が逆浸透膜と接して膜を透過する機会が多くなり、濃縮液中のリン酸以外の酸の濃度をさらに低くすることができる。このときリン酸濃度が１５重量％を超えると膜処理が行えなくなるので、濃縮液に希釈水を加え希釈して循環し、逆浸透処理を行うことにより、さらにリン酸以外の酸の濃度を低くすることができ、高純度のリン酸濃縮液を回収することができる。希釈水としては透過水から不純物を除去した回収水を循環して使用することができる。   When membrane treatment is performed while circulating the concentrate, the more times the concentrate is circulated, the more chances of acids other than phosphoric acid passing through the membrane in contact with the reverse osmosis membrane. The acid concentration can be further reduced. At this time, if the phosphoric acid concentration exceeds 15% by weight, membrane treatment cannot be performed. Therefore, diluting water is added to the concentrated solution for dilution and circulation, and reverse osmosis treatment is performed to further reduce the concentration of acids other than phosphoric acid. And a high-purity phosphoric acid concentrate can be recovered. As the dilution water, recovered water from which impurities have been removed from the permeated water can be circulated and used.

透過液室側から取出される逆浸透装置の透過水は、透過したリン酸、硝酸、酢酸等の酸を含んでいるので、逆浸透装置の透過水からこれらの酸その他の不純物を不純物除去装置によって除去することにより、純水を回収することができる。この場合、不純物除去装置としてはイオン交換樹脂を用いるイオン交換装置を採用することができる。透過水をアニオン交換樹脂層に通水することにより、これら酸、その他のアニオンを除去し、またカチオン交換樹脂層およびアニオン交換樹脂層、またはこれらの混床に通水することにより、酢酸や硝酸等のリン酸以外の酸、その他のアニオン、ならびに残留するカチオンを除去し、純水を回収することができる。ここで用いるアニオン交換樹脂としては、ＯＨ形強塩基性あるいは弱塩基性アニオン交換樹脂が好ましく、またカチオン交換樹脂としては、Ｈ形強酸性カチオン交換樹脂が好ましい。   The permeated water of the reverse osmosis device taken out from the permeate chamber side contains permeated acids such as phosphoric acid, nitric acid, and acetic acid, so that these acids and other impurities are removed from the permeated water of the reverse osmosis device. It is possible to recover pure water by removing by the above. In this case, an ion exchange device using an ion exchange resin can be employed as the impurity removal device. By passing permeate through the anion exchange resin layer, these acids and other anions are removed, and by passing through the cation exchange resin layer and the anion exchange resin layer, or a mixed bed thereof, acetic acid and nitric acid. Pure water can be recovered by removing acids other than phosphoric acid such as phosphoric acid, other anions, and remaining cations. The anion exchange resin used here is preferably an OH-type strongly basic or weakly basic anion exchange resin, and the cation exchange resin is preferably an H-type strongly acidic cation exchange resin.

一般的なイオン交換装置では、イオン交換樹脂の再生はカチオン交換樹脂の再生には酸、アニオン交換樹脂の再生にはアルカリを再生剤として再生するが、このような再生方法では再生剤が必要な上、再生廃液が発生するなどの不利があるため、電気再生式イオン交換装置を採用するのが好ましい。電気再生式イオン交換装置は、イオン交換樹脂層をカチオン交換樹脂膜およびアニオン交換樹膜で区画し、両端部に陰極および陽極を配置した装置であり、電気透析装置と同様に、陰極および陽極に通電して再生しながら通液してイオン交換を行う。この場合、再生のための特別の操作および再生剤が不要で、連続して酸その他の不純物を取り出し、純水を回収することができる。電気再生式イオン交換装置に用いるイオン交換樹脂は、酸その他のアニオンの除去のみを目的とする場合は、アニオン交換樹脂のみを充填することができるが、残留する他のカチオンの除去も目的とする場合は、カチオン交換樹脂およびアニオン交換樹脂の混床を充填することができる。再生により排出される酸濃縮液はリン酸、硝酸、酢酸等の濃縮液となっているので、生物脱窒法により処理することができる。   In a general ion exchange apparatus, regeneration of an ion exchange resin uses an acid as a regeneration agent for regeneration of a cation exchange resin, and alkali as a regeneration agent for regeneration of an anion exchange resin, but such a regeneration method requires a regeneration agent. In addition, it is preferable to employ an electric regeneration type ion exchange apparatus because of disadvantages such as generation of a regenerated waste liquid. An electroregenerative ion exchange device is a device in which an ion exchange resin layer is partitioned by a cation exchange resin membrane and an anion exchange resin membrane, and a cathode and an anode are arranged at both ends. Ion exchange is performed by passing liquid while regenerating by energization. In this case, a special operation and a regenerant for regeneration are not required, and acid and other impurities can be continuously taken out and pure water can be recovered. The ion exchange resin used in the electric regenerative ion exchange apparatus can be filled only with an anion exchange resin when the purpose is only to remove acids and other anions, but it is also intended to remove other remaining cations. In some cases, a mixed bed of cation exchange resin and anion exchange resin can be filled. Since the acid concentrate discharged by regeneration is a concentrate such as phosphoric acid, nitric acid, and acetic acid, it can be treated by a biological denitrification method.

一方、濃縮液室側から取出されるリン酸濃縮液は、硝酸や酢酸等のリン酸以外の酸の大部分は除去されているが、さらにこれらを除去して回収リン酸液の純度、濃度を高めるために後処理による精製を行うことができる。後処理による精製として、リン酸濃縮液からアニオン交換によりリン酸以外の酸を除去して精製することができる。この場合、精製装置としてアニオン交換装置を設けて、濃縮液をアニオン交換樹脂層に通水し、濃縮液から硝酸などの強酸イオンを除去し、硝酸などの強酸イオンを殆ど含まない高濃度のリン酸を回収することができる。逆浸透装置が濃縮液を循環して濃縮を行う場合、精製装置は逆浸透装置の濃縮液循環ラインに設けることができるが、循環ラインから濃縮液を抜き出すラインに設けることが好ましい。アニオン交換樹脂は、ＯＨ形またはＰＯ４形の強塩基性アニオン交換樹脂が好ましい。 On the other hand, the phosphoric acid concentrate taken out from the concentrate chamber side has most of the acid other than phosphoric acid such as nitric acid and acetic acid removed, but these are further removed to obtain the purity and concentration of the recovered phosphoric acid solution. In order to increase the efficiency, purification by post-treatment can be performed. As purification by post-treatment, it can be purified by removing acids other than phosphoric acid from the phosphoric acid concentrate by anion exchange. In this case, an anion exchange device is provided as a purification device, the concentrated solution is passed through the anion exchange resin layer, strong acid ions such as nitric acid are removed from the concentrated solution, and high concentration phosphorous containing almost no strong acid ions such as nitric acid is removed. The acid can be recovered. When the reverse osmosis apparatus circulates the concentrate to perform concentration, the purification apparatus can be provided in the concentrate circulatory line of the reverse osmosis apparatus, but is preferably provided in a line for extracting the concentrate from the circulation line. The anion exchange resin is preferably a strongly basic anion exchange resin of OH type or PO 4 type .

リン酸濃縮液中に酢酸が残留している場合、酢酸はアニオン交換樹脂によっても完全に除去できないので、酢酸等の揮発性成分を除去して回収リン酸液の純度、濃度を高めるためには、リン酸濃縮液を蒸発濃縮装置で蒸発濃縮して、水とともに揮発性成分を除去して濃縮し、酢酸などの揮発性成分を殆ど含まない高濃度のリン酸を回収することができる。蒸発濃縮装置としては、ロータリエバポレータ等の公知の装置が使用できる。   If acetic acid remains in the phosphoric acid concentrate, acetic acid cannot be completely removed even with an anion exchange resin. In order to increase the purity and concentration of the recovered phosphoric acid solution by removing volatile components such as acetic acid. The concentrated phosphoric acid solution is evaporated and concentrated with an evaporating and concentrating apparatus, and volatile components are removed together with water and concentrated to recover high-concentration phosphoric acid containing almost no volatile components such as acetic acid. A known device such as a rotary evaporator can be used as the evaporative concentration device.

上記により回収されるリン酸は、回収物として有用であり、かつ高濃度の液状で運搬可能であり、しかも高純度の濃縮リン酸として回収できる。この場合、ｐＨ３以下の条件下で逆浸透処理するが、原水としてのカチオンを除去したリン酸含有水は通常ｐＨ３以下の酸性の状態で得られるので、塩酸等のｐＨ調整剤を注入することにより容易に調整することができる。また回収のための方法および装置は、簡単な構成と操作により、ｐＨ３以下、かつリン酸濃度１〜１５重量％の条件下で逆浸透処理することにより、リン酸濃縮液として回収することが可能である。これにより再生剤の使用量、廃棄物の生成量を少なくし、処理コストを低くして、高純度の濃縮リン酸および純水を回収することができる。 The phosphoric acid recovered by the above is useful as a recovered material, can be transported in a high concentration liquid state, and can be recovered as concentrated phosphoric acid with high purity. In this case, reverse osmosis treatment is carried out under the condition of pH 3 or lower, but since the phosphoric acid-containing water from which cations as raw water are removed is usually obtained in an acidic state of pH 3 or lower, by injecting a pH adjuster such as hydrochloric acid. It can be adjusted easily. The method and apparatus for recovery can be recovered as a phosphate concentrate by reverse osmosis treatment with a simple configuration and operation under conditions of pH 3 or lower and a phosphoric acid concentration of 1 to 15% by weight. It is. As a result, the amount of regenerant used and the amount of waste generated can be reduced, the processing cost can be reduced, and high-purity concentrated phosphoric acid and pure water can be recovered.

以上の通り本発明によれば、カチオンを除去したリン酸含有水をｐＨ３以下、かつリン酸濃度１〜１５重量％の条件下で逆浸透装置に供給して逆浸透処理を行い、リン酸以外の酸を水とともに透過液室側に透過させて、リン酸を濃縮液室側に濃縮し、リン酸濃縮液を回収するようにしたので、簡単な構成と操作により、高濃度の液状で運搬可能であり、回収物として有用な高純度のリン酸を、リン酸含有水から低コストで、かつ効率よく回収することができる。 As described above, according to the present invention, phosphoric acid-containing water from which cations have been removed is supplied to a reverse osmosis device under conditions of pH 3 or lower and a phosphoric acid concentration of 1 to 15% by weight. The acid is permeated to the permeate chamber side with water, and the phosphoric acid is concentrated to the concentrate chamber side, and the phosphoric acid concentrate is recovered, so it is transported as a highly concentrated liquid with a simple configuration and operation. High-purity phosphoric acid that is possible and useful as a recovered product can be efficiently recovered from phosphoric acid-containing water at low cost.

本発明の実施の形態を図面により説明する。図１は実施形態におけるリン酸回収方法および装置のフロー図である。１は原水槽で、原水１ａを貯留する。２はカチオン交換塔で、カチオン交換樹脂層２ａを有する。３はアニオン交換塔で、アニオン交換樹脂層３ａを有する。４は濃縮液槽で、濃縮液４ａを貯留する。５は逆浸透装置で、逆浸透膜５ａにより、透過液室５ｂと濃縮液室５ｃに区画されている。６は電気再生式イオン交換装置で、脱塩室６ａと濃縮室６ｂがアニオン交換膜６ｃで区画され、脱塩室６ａの外側にカチオン交換膜６ｄにより陰極室６ｅが区画され、濃縮室６ｂの外側にカチオン交換膜６ｆにより陽極室６ｇが区画され、脱塩室６ａと濃縮室６ｂに混床式イオン交換層６ｈ、６ｉが充填され、陰極室６ｅに陰極（−）、陽極室６ｇに陽極（＋）が設けられている。７は回収水槽で、回収水７ａを貯留する。８は蒸発濃縮装置で、蒸留により揮発性成分を水とともに蒸発させて分離し、リン酸液を濃縮する。９は回収リン酸槽で、回収リン酸液９ａを貯留する。１０は生物脱窒装置である。   Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart of a phosphoric acid recovery method and apparatus according to an embodiment. Reference numeral 1 denotes a raw water tank which stores raw water 1a. Reference numeral 2 denotes a cation exchange tower having a cation exchange resin layer 2a. Reference numeral 3 denotes an anion exchange tower having an anion exchange resin layer 3a. 4 is a concentrated liquid tank and stores the concentrated liquid 4a. A reverse osmosis device 5 is divided into a permeate chamber 5b and a concentrate chamber 5c by a reverse osmosis membrane 5a. 6 is an electric regenerative ion exchange device, in which a desalting chamber 6a and a concentration chamber 6b are partitioned by an anion exchange membrane 6c, and a cathode chamber 6e is partitioned by a cation exchange membrane 6d outside the desalting chamber 6a. The anode chamber 6g is partitioned on the outside by a cation exchange membrane 6f, the desalting chamber 6a and the concentration chamber 6b are filled with mixed-bed ion exchange layers 6h and 6i, the cathode chamber 6e has a cathode (-), and the anode chamber 6g has an anode. (+) Is provided. Reference numeral 7 denotes a recovered water tank that stores recovered water 7a. 8 is an evaporative concentration apparatus, which evaporates and separates volatile components together with water, and concentrates the phosphoric acid solution. Reference numeral 9 denotes a recovered phosphoric acid tank, which stores the recovered phosphoric acid solution 9a. Reference numeral 10 denotes a biological denitrification apparatus.

図１において、Ｐは加圧ポンプであり、原水槽１、カチオン交換塔２、アニオン交換塔３および濃縮液槽４とともに原水供給部を構成し、このうちカチオン交換塔２およびアニオン交換塔３が前処理装置を構成する。電気再生式イオン交換装置６および回収水槽７は透過液取出部を構成し、このうち電気再生式イオン交換装置６は不純物除去装置を構成する。また蒸発濃縮装置８および回収リン酸槽９は濃縮リン酸液取出部を構成し、このうち蒸発濃縮装置８は精製装置を構成する。   In FIG. 1, P is a pressure pump, and constitutes a raw water supply unit together with a raw water tank 1, a cation exchange tower 2, an anion exchange tower 3 and a concentrated liquid tank 4, and among them, the cation exchange tower 2 and the anion exchange tower 3 A pre-processing device is configured. The electric regenerative ion exchange device 6 and the recovery water tank 7 constitute a permeate extraction unit, and among these, the electric regenerative ion exchange device 6 constitutes an impurity removal device. The evaporating and concentrating device 8 and the recovered phosphoric acid tank 9 constitute a concentrated phosphoric acid liquid take-out section, and among these, the evaporating and concentrating device 8 constitutes a purification device.

上記のリン酸回収装置では、前処理工程として沈殿分離、濾過等による不純物の除去を行った原水１ａ（リン酸イオン含有水）をラインＬ１から原水槽１に導入する。原水槽１の原水１ａはラインＬ２からカチオン交換塔２に導入して通水し、カチオン交換樹脂層２ａでカチオン交換して、原水に含まれるインジウム、その他の金属イオン等のカチオンを交換吸着して除去する。カチオン交換樹脂層２ａにはＨ形の強酸性カチオン交換樹脂を用いるのが好ましい。カチオン交換樹脂層２ａが飽和したときは、ラインＬ３から塩酸等の酸を含む再生剤を通液して再生し、溶離したカチオンをラインＬ４から回収する。   In the phosphoric acid recovery apparatus, raw water 1a (phosphate ion-containing water) that has been subjected to removal of impurities by precipitation separation, filtration or the like as a pretreatment step is introduced from the line L1 into the raw water tank 1. The raw water 1a in the raw water tank 1 is introduced into the cation exchange tower 2 from the line L2 and passed therethrough, and cation exchange is performed in the cation exchange resin layer 2a to exchange and adsorb cations such as indium and other metal ions contained in the raw water. To remove. It is preferable to use an H-type strongly acidic cation exchange resin for the cation exchange resin layer 2a. When the cation exchange resin layer 2a is saturated, it is regenerated by passing a regenerant containing an acid such as hydrochloric acid from the line L3, and the eluted cations are recovered from the line L4.

カチオン交換塔２の処理水である脱カチオン水をラインＬ５からアニオン交換塔３に導入して通水し、アニオン交換樹脂層３ａでアニオン交換して、原水に含まれる過塩素酸、有機酸錯体等のアニオンを交換吸着して除去する。アニオン交換樹脂層３ａには酸形の強塩基性アニオン交換樹脂を用いるのが好ましい。アニオン交換樹脂層３ａが飽和したときは、ラインＬ６から水酸化ナトリウム等のアルカリを含む再生剤を通液して再生し、溶離したアニオンをラインＬ７から回収する。その後、ラインＬ６からリン酸などの酸を通液し、アニオン交換樹脂を酸形とする。   Decationized water, which is treated water of the cation exchange tower 2, is introduced into the anion exchange tower 3 from the line L5 and passed therethrough, and anion exchange is performed in the anion exchange resin layer 3a, so that perchloric acid and organic acid complex contained in the raw water are obtained. Anion such as is removed by exchange adsorption. For the anion exchange resin layer 3a, it is preferable to use a strongly basic anion exchange resin in the acid form. When the anion exchange resin layer 3a is saturated, it is regenerated by passing a regenerant containing an alkali such as sodium hydroxide from the line L6, and the eluted anion is recovered from the line L7. Thereafter, an acid such as phosphoric acid is passed through the line L6 to convert the anion exchange resin into an acid form.

アニオン交換塔３の処理水をラインＬ８から濃縮液槽４に導入する。原水としてのカチオンを除去したリン酸含有水は通常ｐＨ３以下の酸性の状態で得られるので、ｐＨ３以下の条件で逆浸透処理するには、そのまま逆浸透装置４に供給すればよい。ｐＨが高い原水をｐＨ調整する場合は、リン酸含有水はｐＨ３に近い状態で得られるので、ラインＬ８または濃縮液槽４に塩酸等のｐＨ調整剤を注入することにより容易に調整することができる。 The treated water of the anion exchange tower 3 is introduced into the concentrate tank 4 from the line L8. Obtained by cationic phosphate-containing water to remove the normal pH3 following acidic conditions as the raw water Runode, the reverse osmosis treatment in pH3 following conditions may be supplied to the reverse osmosis device 4 as it is. When adjusting the pH of raw water having a high pH, the phosphoric acid-containing water is obtained in a state close to pH 3, so that it can be easily adjusted by injecting a pH adjusting agent such as hydrochloric acid into the line L8 or the concentrate tank 4. it can.

濃縮液槽４のカチオンを除去したリン酸含有水は加圧ポンプＰで加圧してラインＬ１１から逆浸透装置５の濃縮液室５ｃに導入し、逆浸透膜５ａにより膜分離（逆浸透処理）を行って、硝酸、酢酸等のリン酸以外の酸を水とともに透過液室５ｂ側に透過させて、リン酸を濃縮液室５ｃ側に濃縮する。リン酸含有水を中和して中性の状態で逆浸透処理すると、硝酸、酢酸等のリン酸以外の酸の塩と、リン酸の塩のいずれも逆浸透膜５ａを透過せず、濃縮液室５ｃ側に濃縮される。これに対してカチオンを除去したリン酸含有水を中和することなく、ｐＨ３以下の条件下で逆浸透装置５に導入して逆浸透処理を行うと、リン酸は逆浸透膜５ａにより透過を阻止されて濃縮液室５ｃ側に濃縮されるが、硝酸、酢酸等のリン酸以外の酸は水とともに透過液室５ｂ側に透過して分離される。逆浸透装置５に導入するリン酸含有水は脱カチオンされているため、逆浸透膜５ａの目詰まりがなく、逆浸透処理の効率は高く維持される。 Phosphoric acid-containing water from which cations in the concentrate tank 4 have been removed is pressurized with a pressure pump P and introduced into the concentrate chamber 5c of the reverse osmosis device 5 from the line L11, and membrane separation (reverse osmosis treatment) by the reverse osmosis membrane 5a. Then, an acid other than phosphoric acid such as nitric acid and acetic acid is allowed to permeate to the permeate chamber 5b side together with water to concentrate phosphoric acid to the concentrate chamber 5c side. When neutralizing phosphoric acid-containing water and performing reverse osmosis treatment, neither acid salts other than phosphoric acid such as nitric acid and acetic acid and phosphoric acid salts pass through the reverse osmosis membrane 5a and are concentrated. It is concentrated on the liquid chamber 5c side. On the other hand, when the reverse osmosis treatment is performed by introducing into the reverse osmosis device 5 under the condition of pH 3 or less without neutralizing the phosphoric acid-containing water from which cations have been removed , phosphoric acid permeates through the reverse osmosis membrane 5a. Although blocked and concentrated on the concentrated liquid chamber 5c side, acids other than phosphoric acid such as nitric acid and acetic acid permeate to the permeated liquid chamber 5b side together with water and are separated. Since the phosphoric acid-containing water introduced into the reverse osmosis device 5 is decationized, the reverse osmosis membrane 5a is not clogged, and the efficiency of the reverse osmosis treatment is maintained high.

ラインＬ８から得られる原水としてのリン酸含有水がリン酸濃度１〜１５重量％で得られる場合は、そのまま膜分離処理を行って逆浸透による分離を行うことができるが、リン酸濃度１重量％未満の場合は、濃縮液室５ｃからラインＬ１２を通して取出した濃縮液を、循環経路であるラインＬ１３から濃縮液槽に循環しながら膜分離処理を行うことにより、リン酸濃度１重量％以上に濃縮することができる。この場合、低濃度のリン酸含有水を循環しながら濃縮し、リン酸濃度１重量％以上に濃縮された時点で循環液を入れ替える回分式の処理を行ってもよいが、リン酸濃度１〜１５重量％に濃縮された濃縮液を循環しながら、循環する濃縮液に低濃度の被処理リン酸含有水を加え、濃縮液を一部ずつラインＬ１４からリン酸濃縮液として取出すと、見掛け上一過式の処理が行えるので好ましい。   When the phosphoric acid-containing water as raw water obtained from the line L8 is obtained at a phosphoric acid concentration of 1 to 15% by weight, the membrane separation treatment can be performed as it is to perform separation by reverse osmosis, but the phosphoric acid concentration is 1% by weight. If the concentration is less than%, the membrane separation process is performed while circulating the concentrate taken out from the concentrate chamber 5c through the line L12 to the concentrate tank from the line L13, which is the circulation path, so that the phosphoric acid concentration becomes 1% by weight or more. It can be concentrated. In this case, concentration may be performed while circulating low-concentration phosphoric acid-containing water, and when the phosphoric acid concentration is concentrated to 1% by weight or more, a batch process may be performed in which the circulating fluid is replaced. While circulating the concentrated solution concentrated to 15% by weight, adding low-concentration treated phosphoric acid-containing water to the circulating concentrated solution, and removing the concentrated solution partly as a phosphoric acid concentrated solution from the line L14, apparently This is preferable because a one-time process can be performed.

逆浸透装置５の透過液室５ｂに透過した透過液はラインＬ１５から電気再生式イオン交換装置６の脱塩室６ａへ導入し、陽極（＋）と陰極（−）間に電圧を印加して電気再生しながら、イオン交換により脱塩する。これにより透過液に含まれるリン酸、硝酸、酢酸等のアニオン、ならびに残留するカチオンを交換吸着により除去して精製を行い、処理水はラインＬ１６から回収水槽７へ取り出し、回収水７ａとして貯留する。脱塩室６ａでは、混床式イオン交換層６ｈに吸着された酸等のアニオンがアニオン交換膜６ｃを通して濃縮室６ｂへ透過し、混床式イオン交換層６ｉに吸着されるので、ラインＬ１７から透過液の一部を濃縮室６ｂへ流しながら再生により吸着されたアニオンを溶離させ、ラインＬ１８から生物脱窒装置１０へ送って生物脱窒処理する。混床式イオン交換層６ｈに吸着されたカチオンは陰極室６ｅへ透過するので、陽極室６ｇからラインＬ１９を通して陰極室６ｅへ電極液を流し、ラインＬ２０から排出する。   The permeate that has permeated into the permeate chamber 5b of the reverse osmosis device 5 is introduced from the line L15 into the desalting chamber 6a of the electric regenerative ion exchange device 6, and a voltage is applied between the anode (+) and the cathode (−). Desalting by ion exchange while regenerating electricity. As a result, the anion such as phosphoric acid, nitric acid, and acetic acid contained in the permeate and the remaining cations are removed by exchange adsorption for purification, and the treated water is taken out from the line L16 to the recovered water tank 7 and stored as recovered water 7a. . In the desalting chamber 6a, anions such as acids adsorbed on the mixed bed ion exchange layer 6h permeate to the concentration chamber 6b through the anion exchange membrane 6c and are adsorbed on the mixed bed ion exchange layer 6i. The anion adsorbed by the regeneration is eluted while flowing a part of the permeate to the concentration chamber 6b, and sent to the biological denitrification apparatus 10 from the line L18 to perform the biological denitrification treatment. Since the cations adsorbed on the mixed bed type ion exchange layer 6h permeate the cathode chamber 6e, the electrode solution flows from the anode chamber 6g through the line L19 to the cathode chamber 6e and is discharged from the line L20.

逆浸透装置５の濃縮液室５ｃで濃縮され、ラインＬ１４から取出される濃縮液の一部は、蒸発濃縮装置８に導入して蒸留し、水とともに酢酸等の揮発性成分を蒸発させて分離し、ラインＬ２１から排出する。蒸発濃縮装置８で揮発性成分を除去し濃縮したリン酸濃縮液は、ラインＬ２２から回収リン酸槽９に導入し、回収リン酸液９ａとして貯留する。蒸発濃縮装置８としてはロータリエバポレータ等の公知の蒸発濃縮装置を用いることができる。   A part of the concentrated liquid concentrated in the concentrated liquid chamber 5c of the reverse osmosis apparatus 5 and taken out from the line L14 is introduced into the evaporative concentration apparatus 8 and distilled, and separated by evaporating volatile components such as acetic acid together with water. And discharged from the line L21. The phosphoric acid concentrated liquid obtained by removing the volatile components by the evaporation concentrating apparatus 8 and concentrating is introduced into the recovered phosphoric acid tank 9 from the line L22 and stored as the recovered phosphoric acid liquid 9a. As the evaporative concentration apparatus 8, a known evaporative concentration apparatus such as a rotary evaporator can be used.

逆浸透装置５における膜分離（逆浸透処理）を、リン酸含有水がｐＨ３以下、かつリン酸濃度１〜１５重量％の条件下で行うことにより、リン酸以外の酸を高透過率で透過させ、リン酸の順度を高めることができるが、濃縮液中のリン酸以外の酸の濃度をさらに低くするためには、濃縮液を循環して膜分離の機会を多くすることにより、これらの酸が透過する機会を多くして透過率を高めることができる。この場合、水の透過も起こるため、循環液は濃縮されることになる。このため循環する濃縮液に希釈水を加えて逆浸透処理を行うことにより、リン酸以外の酸の除去率を高めることができる。希釈水としては透過水から不純物を除去した回収水を使用することができる。   Membrane separation (reverse osmosis treatment) in the reverse osmosis device 5 is carried out under conditions where the phosphoric acid-containing water has a pH of 3 or less and the phosphoric acid concentration is 1 to 15% by weight, so that acids other than phosphoric acid can be permeated with high permeability. However, in order to further reduce the concentration of acids other than phosphoric acid in the concentrate, these concentrates can be circulated to increase the opportunities for membrane separation. It is possible to increase the transmittance by increasing the opportunity for the acid to permeate. In this case, since the permeation of water also occurs, the circulating fluid is concentrated. For this reason, the removal rate of acids other than phosphoric acid can be raised by adding dilution water to the circulating concentrate and performing reverse osmosis treatment. As the dilution water, recovered water obtained by removing impurities from the permeated water can be used.

このため図１では、希釈水として回収水槽７から回収水７ａを、ポンプＰ２によりラインＬ１６を通して濃縮液槽４へ供給し、循環する濃縮液を希釈して逆浸透処理を行うことにより、さらにリン酸以外の酸の濃度を低くすることができ、高純度のリン酸濃縮液を回収することができる。濃縮液槽４へ供給する回収水７ａの量は、循環する濃縮液がリン酸濃度１〜１５重量％の条件を維持する量である。これにより循環する濃縮液が高濃縮されることによるリン酸以外の酸の透過効率が低下するのを防止して、濃縮液のリン酸純度を高めることができる。   For this reason, in FIG. 1, the recovered water 7a is supplied as dilution water from the recovered water tank 7 through the line L16 to the concentrated liquid tank 4 by the pump P2, and the circulating concentrated liquid is diluted to perform reverse osmosis treatment, thereby further increasing the phosphorus concentration. The concentration of an acid other than the acid can be lowered, and a high-purity phosphoric acid concentrate can be recovered. The amount of the recovered water 7a supplied to the concentrated liquid tank 4 is an amount that maintains the condition that the circulating concentrated liquid has a phosphoric acid concentration of 1 to 15% by weight. Thereby, it can prevent that the permeation | transmission efficiency of acids other than phosphoric acid by the highly concentrated circulating concentrate is reduced, and can raise the phosphoric acid purity of a concentrate.

上記の方法で回収されるリン酸液９ａは、回収物として有用であり、かつ高濃度の液状で回収されるため実用上運搬可能であり、しかも高純度の濃縮リン酸として回収できる。この場合、ｐＨ３以下の条件下で逆浸透処理するが、原水としてのカチオンを除去したリン酸含有水は通常ｐＨ３以下の酸性の状態で得られるのでそのまま供給すればよく、特にｐＨ調整する必要がない。酸、アルカリ等の薬剤はカチオン交換塔２におけるカチオン用の再生剤、ならびにアニオン交換塔３におけるアニオン用の再生剤に限られ、リン酸回収用ならびに透過水の精製用としては必要でない。また回収のための方法および装置は、簡単な構成と操作により、ｐＨ３以下、かつリン酸濃度１〜１５重量％の条件下で逆浸透処理することにより、リン酸濃縮液として回収することが可能である。これにより薬剤の使用量、廃棄物の生成量を少なくし、処理コストを低くして、高純度の濃縮リン酸および純水を回収することができる。
The phosphoric acid solution 9a recovered by the above method is useful as a recovered product and can be transported practically because it is recovered as a high-concentration liquid, and can be recovered as highly purified concentrated phosphoric acid. In this case, the reverse osmosis treatment is performed under the condition of pH 3 or less, but the phosphoric acid-containing water from which the cation as raw water has been removed is usually obtained in an acidic state of pH 3 or less, so it may be supplied as it is, and it is particularly necessary to adjust the pH. Absent. The chemicals such as acid and alkali are limited to the cation regenerating agent in the cation exchange column 2 and the anion regenerating agent in the anion exchange column 3, and are not necessary for recovering phosphoric acid and purifying permeate. The method and apparatus for recovery can be recovered as a phosphate concentrate by reverse osmosis treatment with a simple configuration and operation under conditions of pH 3 or lower and a phosphoric acid concentration of 1 to 15% by weight. It is. Thereby, the amount of chemicals used and the amount of waste generated can be reduced, the processing cost can be reduced, and high-purity concentrated phosphoric acid and pure water can be recovered.

図１のリン酸回収方法および装置では、リン酸含有水をｐＨ３以下、かつリン酸濃度１〜１５重量％の条件下で逆浸透装置５に供給して逆浸透膜５ａにより逆浸透処理を行い、リン酸以外の酸を水とともに透過液室５ｂ側に透過させて、リン酸を濃縮液室５ｃ側に濃縮し、純水およびリン酸濃縮液を回収することにより、簡単な構成と操作によって、高濃度の液状で運搬可能であり、回収物として有用な高純度のリン酸および純水を、リン酸含有水から低コストで、かつ効率よく回収することができる。   In the phosphoric acid recovery method and apparatus of FIG. 1, phosphoric acid-containing water is supplied to the reverse osmosis device 5 under conditions of pH 3 or lower and phosphoric acid concentration of 1 to 15% by weight, and reverse osmosis treatment is performed by the reverse osmosis membrane 5a. By allowing permeation of acids other than phosphoric acid together with water to the permeate chamber 5b side, concentrating phosphoric acid to the concentrate chamber 5c side, and collecting pure water and phosphoric acid concentrate, the simple configuration and operation High-purity phosphoric acid and pure water that can be transported in a high-concentration liquid form and are useful as a recovered product can be efficiently recovered from phosphoric acid-containing water at low cost.

なお、本発明の実施の形態は図１に限定されるものでなく、例えば、回収リン酸液の純度を更に高めるために、第二のアニオン交換塔をラインＬ１４の蒸発濃縮装置８の前段に設けることもできる。また、本実施の形態では、逆浸透装置５からの透過液を精製する電気再生式イオン交換装置６は、脱塩室６ａと濃縮室６ｂとがアニオン交換膜６ｃで区画された簡易の電気再生式イオン交換装置が用いられているが、陰極室と陽極室との間に陰イオン交換膜と陽イオン交換膜とを交互に配列して脱塩室と濃縮室とを形成し、該脱塩室にイオン交換体を充填した通常の電気脱イオン装置を用いることもできる。   The embodiment of the present invention is not limited to FIG. 1. For example, in order to further increase the purity of the recovered phosphoric acid solution, the second anion exchange column is placed upstream of the evaporation concentrator 8 in the line L14. It can also be provided. In this embodiment, the electric regeneration type ion exchange device 6 for purifying the permeate from the reverse osmosis device 5 is a simple electric regeneration in which the desalting chamber 6a and the concentration chamber 6b are partitioned by an anion exchange membrane 6c. Type ion exchange apparatus is used, and an anion exchange membrane and a cation exchange membrane are alternately arranged between a cathode chamber and an anode chamber to form a desalting chamber and a concentration chamber, and the desalting chamber It is also possible to use a normal electrodeionization apparatus in which the chamber is filled with an ion exchanger.

以下、本発明の実施例について説明する。各例において、％は阻止率以外、ならびに特別な示以外は重量％を示す。   Examples of the present invention will be described below. In each example, “%” indicates a percentage other than the blocking rate and “% by weight” unless otherwise indicated.

〔参考例１、２〕：
＜逆浸透処理＞：
リン酸５５０ｍｇ／Ｌ、硝酸５０ｍｇ／Ｌ、酢酸５０ｍｇ／Ｌを含む伝導率１２２ｍＳ／ｍ、ｐＨ２．４の原水を、日東電工（株）製の逆浸透膜ＥＳ−２０に０．７ＭＰａで通液して逆浸透処理し、５倍濃縮の濃縮液（ブライン）を得た（参考例１）。一方、原水に水酸化ナトリウム水溶液を注入してｐＨ６に調整し、同様に試験した（参考例２）。リン酸、硝酸、酢酸の阻止率の結果を表１に示すが、参考例１ではリン酸は阻止され、硝酸、酢酸は透過しているのに対し、参考例２ではすべてが阻止され、透過しないことが分かる。 [Reference Examples 1 and 2]:
<Reverse osmosis treatment>:
The raw water having a conductivity of 122 mS / m and pH 2.4 containing 550 mg / L of phosphoric acid, 50 mg / L of nitric acid and 50 mg / L of acetic acid was passed through a reverse osmosis membrane ES-20 manufactured by Nitto Denko Corporation at 0.7 MPa. Then, reverse osmosis treatment was performed to obtain a 5-fold concentrated concentrate (brine) (Reference Example 1). On the other hand, a sodium hydroxide aqueous solution was poured into the raw water to adjust to pH 6, and the same test was performed (Reference Example 2). The results of the blocking rates of phosphoric acid, nitric acid and acetic acid are shown in Table 1. In Reference Example 1, phosphoric acid is blocked and nitric acid and acetic acid are permeated, whereas in Reference Example 2, all are blocked and permeated. I understand that I don't.

Figure 0005277559
Figure 0005277559

〔実施例１〕：
参考例１において、濃縮液の循環を回数を高めて上げていったときの濃縮液中のリン酸濃度の変化と、硝酸の阻止率との関係を図２に示す。 [Example 1]:
In Reference Example 1, FIG. 2 shows the relationship between the change in the concentration of phosphoric acid in the concentrated liquid and the inhibition rate of nitric acid when the circulation of the concentrated liquid is increased.

図２より、濃縮液中のリン酸濃度が１重量％以下で硝酸の阻止率がマイナスとなって直線的に低下し、特にリン酸濃度が２重量％以下、さらにはリン酸濃度が４重量％以下で硝酸の透過が促進されることが分かる。酢酸についても同様の結果が得られた。   As shown in FIG. 2, when the concentration of phosphoric acid in the concentrated solution is 1% by weight or less, the rejection of nitric acid is negative and decreases linearly. In particular, the concentration of phosphoric acid is 2% by weight or less, and the concentration of phosphoric acid is 4% by weight. It can be seen that the permeation of nitric acid is promoted at less than%. Similar results were obtained for acetic acid.

〔実施例２、３〕：
図１の装置において、参考例１と同じ逆浸透膜を用い、参考例１と同じリン酸含有水をＨ形強酸性カチオン交換樹脂（三菱化学（株）製、ＤｉａｉｏｎＳＫ１Ｂ）を充填したカチオン交換塔とリン酸形弱塩性アニオン交換樹脂（三菱化学（株）製、ＤｉａｉｏｎＷＡ３０）を充填したアニオン交換塔で処理後、逆浸透装置に供給し濃縮液の希釈を行わないで循環しながら、膜分離を行って１００倍濃縮した（実施例２）、ならびに透過液を電気再生式イオン交換装置で脱塩した回収水を希釈水として濃縮液槽に供給し（供給原水量の２０容量％）、濃縮液を希釈して循環しながら、膜分離を行って１００倍濃縮した（実施例３）ときの濃縮液中の溶質濃度を表２に示す。参考例１で得られた濃縮液を蒸留により全体で１００倍濃縮したと仮定して、計算により求めた溶質濃度を参考例１として併記する。 [Examples 2 and 3]:
In the apparatus of FIG. 1, a cation exchange column using the same reverse osmosis membrane as in Reference Example 1 and filled with the same phosphoric acid-containing water as in Reference Example 1 with an H-type strongly acidic cation exchange resin (DiaionSK1B, manufactured by Mitsubishi Chemical Corporation). And a phosphoric acid form weakly salted anion exchange resin (DiaionWA30, manufactured by Mitsubishi Chemical Corporation), and then supplied to the reverse osmosis unit and circulated without diluting the concentrated solution. And concentrated to 100 times (Example 2), and the recovered water obtained by desalting the permeate with an electric regenerative ion exchanger was supplied as dilution water to the concentrate tank (20% by volume of the amount of raw water supplied) and concentrated. Table 2 shows the solute concentration in the concentrated solution when the membrane was separated and concentrated 100 times (Example 3) while diluting and circulating the solution. Assuming that the concentrated solution obtained in Reference Example 1 was concentrated 100 times in total by distillation, the solute concentration obtained by calculation is also shown as Reference Example 1.

Figure 0005277559
Figure 0005277559

表２より、濃縮液中のリン酸濃度が１重量％以上となる条件で逆浸透処理を行うことにより、濃縮液中のリン酸以外の酸濃度が低下し、さらに濃縮液を希釈して循環しながら逆浸透処理を行うことにより、濃縮液中のリン酸以外の酸濃度がさらに低下し、高純度のリン酸濃縮液を回収できることが分かる。   From Table 2, by performing reverse osmosis treatment under the condition that the concentration of phosphoric acid in the concentrated solution is 1% by weight or more, the concentration of acids other than phosphoric acid in the concentrated solution decreases, and the concentrated solution is further diluted and circulated. It can be seen that by performing reverse osmosis treatment, the concentration of acids other than phosphoric acid in the concentrated solution is further reduced, and a high-purity phosphoric acid concentrated solution can be recovered.

本発明は、リン酸含有水からリン酸および純水を回収する方法および装置、特に液晶基板やウエハーその他の電子機器をエッチングした後の洗浄排水からリン酸などの有価物と、処理水である純水の回収に適したリン酸を回収する方法および装置に利用可能である。   The present invention is a method and apparatus for recovering phosphoric acid and pure water from phosphoric acid-containing water, particularly valuable materials such as phosphoric acid and treated water from cleaning wastewater after etching a liquid crystal substrate, a wafer and other electronic devices. The present invention is applicable to a method and an apparatus for recovering phosphoric acid suitable for recovering pure water.

実施形態におけるリン酸回収方法および装置のフロー図である。It is a flowchart of the phosphoric acid collection | recovery method and apparatus in embodiment. 実施例１の結果を示すグラフである。3 is a graph showing the results of Example 1.

符号の説明Explanation of symbols

１ 原水槽
１ａ 原水
２ カチオン交換塔
２ａ カチオン交換樹脂層
３ アニオン交換塔
３ａ アニオン交換樹脂層
４ 濃縮液槽
４ａ 濃縮液
５ 逆浸透装置
５ａ 逆浸透膜
５ｂ 透過液室
５ｃ 濃縮液室
５ アニオン交換塔
５ａ、７ａ アニオン交換樹脂層
６ 電気再生式イオン交換装置
６ａ 脱塩室
６ｂ 濃縮室
６ｃ アニオン交換膜
６ｄ、６ｆ カチオン交換膜
６ｅ 陰極室
６ｇ 陽極室
６ｈ、６ｉ 混床式イオン交換層
７ 回収水槽
７ａ 回収水
８ 蒸発濃縮装置
９ 回収リン酸槽
９ａ 回収リン酸液
１０ 生物脱窒装置 DESCRIPTION OF SYMBOLS 1 Raw water tank 1a Raw water 2 Cation exchange tower 2a Cation exchange resin layer 3 Anion exchange tower 3a Anion exchange resin layer 4 Concentrated liquid tank 4a Concentrated liquid 5 Reverse osmosis device 5a Reverse osmosis membrane 5b Permeate chamber 5c Concentrated liquid chamber 5 Anion exchange tower 5a, 7a Anion exchange resin layer 6 Electric regeneration type ion exchange device 6a Desalination chamber 6b Concentration chamber 6c Anion exchange membrane 6d, 6f Cation exchange membrane 6e Cathode chamber 6g Anode chamber 6h, 6i Mixed bed type ion exchange layer 7 Recovery water tank 7a Recovered water 8 Evaporative concentration device 9 Recovered phosphoric acid tank 9a Recovered phosphoric acid solution 10 Biological denitrification device

Claims (14)

カチオンを除去したリン酸含有水からリン酸を回収する方法であって、
カチオンを除去したリン酸含有水をｐＨ３以下、かつリン酸濃度１〜１５重量％の条件下で逆浸透装置に供給して膜分離処理を行い、リン酸以外の酸を水とともに透過液室側に透過させて、リン酸を濃縮液室側に濃縮し、リン酸濃縮液を回収することを特徴とするリン酸の回収方法。 A method of recovering phosphoric acid from phosphoric acid-containing water from which cations have been removed ,
Phosphoric acid-containing water from which cations have been removed is supplied to a reverse osmosis device under conditions of pH 3 or lower and a phosphoric acid concentration of 1 to 15% by weight, and membrane separation treatment is performed. A method of recovering phosphoric acid, characterized in that the phosphoric acid is concentrated on the side of the concentrate chamber, and the phosphoric acid concentrate is recovered. 濃縮液室の濃縮液を取出して濃縮液室へ循環する過程を有し、循環する濃縮液にカチオンを除去した被処理リン酸含有水を加えて逆浸透処理を行う請求項１記載の方法。 The method according to claim 1, further comprising the step of taking out the concentrate in the concentrate chamber and circulating it to the concentrate chamber, and performing reverse osmosis treatment by adding water to be treated containing phosphoric acid from which cations have been removed to the circulating concentrate. 濃縮液室の濃縮液を取出して濃縮液室へ循環する過程を有し、循環する濃縮液に希釈水を加えて膜分離処理を行う請求項１または２記載の方法。   The method according to claim 1 or 2, further comprising a step of taking out the concentrate in the concentrate chamber and circulating it to the concentrate chamber, and performing membrane separation treatment by adding dilution water to the circulating concentrate. カチオンを除去したリン酸含有水を逆浸透装置に供給する前に、前処理としてカチオンおよびアニオンを含む不純物の除去を行う請求項１ないし３のいずれかに記載の方法。 Before supplying phosphate-containing water to remove cations reverse osmosis apparatus, a method according to any one of claims 1 to 3 to remove the impurities containing a cationic and A anion as a pretreatment. 逆浸透装置の透過水から酸を含む不純物を除去して純水を回収する請求項１ないし４のいずれかに記載の方法。   The method according to claim 1, wherein impurities containing acid are removed from the permeated water of the reverse osmosis device to recover pure water. 不純物の除去を、電気再生式イオン交換装置により行う請求項５記載の方法。   6. The method according to claim 5, wherein the impurities are removed by an electric regenerative ion exchange apparatus. リン酸濃縮液を蒸発濃縮して、水とともに揮発性成分を除去して濃縮する請求項１ないし６のいずれかに記載の方法。   The method according to any one of claims 1 to 6, wherein the phosphoric acid concentrate is concentrated by evaporation to remove volatile components together with water. 希釈水が透過水から不純物を除去した純水である請求項３記載の方法。   The method according to claim 3, wherein the dilution water is pure water obtained by removing impurities from the permeated water. カチオンを除去したリン酸含有水からリン酸を回収する装置であって、
カチオンを除去したリン酸含有水をｐＨ３以下、かつリン酸濃度１〜１５重量％の条件下で膜分離処理して、リン酸以外の酸を水とともに透過液室側に透過させ、リン酸を濃縮液室側に濃縮する逆浸透装置と、
カチオンを除去したリン酸含有水をｐＨ３以下、かつリン酸濃度１〜１５重量％の条件下で逆浸透装置の濃縮液室側に供給するリン酸含有水供給部と、
逆浸透装置の透過液室側から透過液を取出す透過液取出部と、
逆浸透装置の濃縮液室側から濃縮リン酸液を取出す濃縮リン酸液取出部と、
濃縮リン酸液取出部から取出した濃縮リン酸液を濃縮液室側に循環する循環経路と
を有することを特徴とするリン酸回収装置。 An apparatus for recovering phosphoric acid from phosphoric acid-containing water from which cations have been removed ,
Phosphoric acid-containing water from which cations have been removed is subjected to a membrane separation treatment under conditions of pH 3 or lower and a phosphoric acid concentration of 1 to 15% by weight, and an acid other than phosphoric acid is allowed to permeate to the permeate chamber side together with water. A reverse osmosis device for concentrating to the concentrate chamber side;
A phosphoric acid-containing water supply unit that supplies phosphoric acid-containing water from which cations have been removed to the concentrated liquid chamber side of the reverse osmosis device under conditions of pH 3 or lower and a phosphoric acid concentration of 1 to 15% by weight;
A permeate extractor for extracting permeate from the permeate chamber side of the reverse osmosis device;
A concentrated phosphoric acid solution extraction section for extracting the concentrated phosphoric acid solution from the concentrated liquid chamber side of the reverse osmosis device ;
And a circulation path for circulating the concentrated phosphoric acid solution extracted from the concentrated phosphoric acid solution extraction unit to the concentrated liquid chamber side. 循環経路を循環する濃縮液に希釈水を加える希釈水供給部を有する請求項９記載の装置。 The apparatus of claim 9, further comprising a dilution water supply unit to add dilution water to the concentrated liquid circulating through the circulation path. カチオンおよびアニオンを含む不純物の除去を行う前処理装置を原水供給部に有する請求項９または１０記載の装置。 The apparatus of claim 9 or 10, wherein a pre-processing device in the raw water supply unit for removing impurities including cationic and A anion. 逆浸透装置の透過水から酸を含む不純物を除去する不純物除去装置を有する請求項９ないし１１のいずれかに記載の装置。   The apparatus according to claim 9, further comprising an impurity removing device that removes impurities including acid from the permeated water of the reverse osmosis device. 不純物除去装置が電気再生式イオン交換装置である請求項１２記載の装置。   The apparatus according to claim 12, wherein the impurity removing apparatus is an electric regenerative ion exchange apparatus. リン酸濃縮液を蒸発濃縮して、水とともに揮発性成分を除去して濃縮する蒸発濃縮装置を有する請求項９ないし１３のいずれかに記載の装置。   The apparatus according to any one of claims 9 to 13, further comprising an evaporating and concentrating device for evaporating and concentrating the phosphoric acid concentrated solution to remove volatile components together with water and concentrating.
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