JP5692278B2 - Method and apparatus for treating fluoride-containing water - Google Patents

Method and apparatus for treating fluoride-containing water Download PDF

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JP5692278B2
JP5692278B2 JP2013092660A JP2013092660A JP5692278B2 JP 5692278 B2 JP5692278 B2 JP 5692278B2 JP 2013092660 A JP2013092660 A JP 2013092660A JP 2013092660 A JP2013092660 A JP 2013092660A JP 5692278 B2 JP5692278 B2 JP 5692278B2
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周平 伊澤
周平 伊澤
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Kurita Water Industries Ltd
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Description

本発明は、フッ化物含有水の処理方法及び処理装置に関し、特にフッ化物含有水を逆浸透(RO)膜処理して脱塩水を回収するに当たり、RO膜の閉塞を防止して安定処理を行うと共に、RO膜処理の前処理に使用する薬品量及び発生汚泥量を低減するフッ化物含有水の処理方法及び処理装置に関する。   The present invention relates to a treatment method and a treatment apparatus for fluoride-containing water, and in particular, when a fluoride-containing water is subjected to reverse osmosis (RO) membrane treatment to recover demineralized water, RO membrane clogging is prevented and stable treatment is performed. In addition, the present invention relates to a treatment method and a treatment apparatus for fluoride-containing water that reduce the amount of chemicals used for pretreatment of RO membrane treatment and the amount of generated sludge.

電子ディスプレイ、半導体などの電子工業分野の製造工場においては多種類の薬品が使用されており、主としてエッチング、洗浄などの生産工程ではフッ化水素/フッ化水素酸(HF)、フッ化ホウ素酸(HBF)、フッ化アンモニウム(NHF)等のフッ化物が多量に用いられる。このため、これらの工程からは、このようなフッ化物を含有する排水が大量に発生する。特にシリコンウエハのエッチング工程からは、フッ化物と共にシリカをも含む排水が排出される。また、フッ化アンモニウムが使用されている工程からは更にアンモニウム成分を含む排水が排出される。 Many kinds of chemicals are used in manufacturing plants in the electronics industry such as electronic displays and semiconductors. In production processes such as etching and cleaning, hydrogen fluoride / hydrofluoric acid (HF), boron fluoride acid ( Fluorides such as HBF 4 ) and ammonium fluoride (NH 4 F) are used in large quantities. For this reason, a large amount of waste water containing such a fluoride is generated from these steps. In particular, wastewater containing silica as well as fluoride is discharged from the silicon wafer etching process. Further, wastewater containing an ammonium component is discharged from the process in which ammonium fluoride is used.

従来、フッ化物含有水の処理方法としては、フッ化物含有水をRO膜処理して脱塩水を回収する方法が広く知られている。しかし、フッ化物含有水にシリカが多く含まれている場合、RO膜処理によりシリカが濃縮されてRO膜表面で析出し、膜を閉塞させる問題がある。
そこで、フッ化物含有水をpHを10〜11に調整した後、RO膜処理を行うことで、シリカの析出を抑制する方法が提案されている(特許文献1参照)。
Conventionally, as a method for treating fluoride-containing water, a method of recovering desalted water by treating the fluoride-containing water with an RO membrane is widely known. However, when the fluoride-containing water contains a large amount of silica, there is a problem that the silica is concentrated by the RO membrane treatment and deposited on the surface of the RO membrane, thereby blocking the membrane.
Then, after adjusting pH of fluoride containing water to 10-11, the method which suppresses precipitation of a silica by performing RO membrane process is proposed (refer patent document 1).

また、フッ化物含有水にカルシウム化合物を添加し、フッ化カルシウムを析出させて固液分離することで、フッ化物濃度を低減した後RO膜処理する方法も一般に広く知られている。しかし、カルシウム化合物を添加し、固液分離して得られる処理水はカルシウム濃度が高いため、これをそのままRO膜処理すると、RO膜表面で炭酸カルシウムが析出し、膜閉塞を発生させる。
そこで、このようなフッ化物濃度低減水に炭酸塩を添加し、炭酸カルシウムを析出させてカルシウムを低減した後、RO膜処理を行うことで、炭酸カルシウムの析出を抑制しながら脱塩水を回収する方法が提案されている(特許文献2参照)。
In addition, a method of performing RO membrane treatment after reducing the fluoride concentration by adding a calcium compound to fluoride-containing water, precipitating calcium fluoride and performing solid-liquid separation is also widely known. However, since the treated water obtained by adding a calcium compound and performing solid-liquid separation has a high calcium concentration, if this is treated as it is, the calcium carbonate is deposited on the surface of the RO membrane, causing membrane clogging.
Therefore, after adding carbonate to such fluoride concentration-reduced water and precipitating calcium carbonate to reduce calcium, RO membrane treatment is performed to recover demineralized water while suppressing precipitation of calcium carbonate. A method has been proposed (see Patent Document 2).

特許4910120号公報Japanese Patent No. 4910120 特開2010−82546号公報JP 2010-82546 A

特許文献1の技術では、酸性のフッ化物含有水に水酸化ナトリウム等のアルカリ剤を添加してpH10〜11に調整する。そのため、塩類濃度が高くなり、RO膜処理において高い運転圧力が必要となり、ポンプ等の運転コストが高くなる問題があった。また、フッ化物含有水中にシリカとともにアルミニウムが共存している場合には、負の電荷を有するSi(OH)と正の電荷を有するAl(OH)がRO膜に吸着、堆層することにより膜閉塞が発生するという問題もあった。
また、特許文献2の技術では、カルシウムを除去するために多量の炭酸塩を必要とするとともに、炭酸カルシウム由来の汚泥が大量に発生するという問題があった。
In the technique of Patent Document 1, an alkaline agent such as sodium hydroxide is added to acidic fluoride-containing water to adjust the pH to 10-11. For this reason, there is a problem that the salt concentration becomes high, high operating pressure is required in the RO membrane treatment, and the operating cost of the pump and the like becomes high. In addition, when aluminum is present together with silica in fluoride-containing water, negatively charged Si (OH) 3 O and positively charged Al (OH) 3 are adsorbed on the RO membrane and deposited. As a result, there is also a problem that membrane clogging occurs.
The technique of Patent Document 2 has a problem that a large amount of carbonate is required to remove calcium, and a large amount of sludge derived from calcium carbonate is generated.

本発明は上記従来の問題点を解決し、フッ化物含有水をRO膜処理して脱塩水を回収するに当たり、RO膜の閉塞を防止して安定処理を行うと共に、RO膜処理の前処理に使用する薬品量及び発生汚泥量を低減するフッ化物含有水の処理方法及び処理装置を提供することを課題とする。   The present invention solves the above-mentioned conventional problems, and in performing RO membrane treatment of fluoride-containing water and recovering demineralized water, RO membrane clogging is prevented and stable treatment is performed, and RO membrane treatment is pre-treated. It is an object of the present invention to provide a treatment method and a treatment apparatus for fluoride-containing water that reduce the amount of chemicals to be used and the amount of generated sludge.

本発明者らは上記課題を解決すべく鋭意検討を重ねた結果、フッ化物含有水へのカルシウム化合物の添加量をフッ化物含有水中のフッ化物の反応当量よりも不足量とすることで、残留するカルシウム濃度を低減することができ、炭酸塩によるカルシウム除去工程を不要とすることができることを見出した。また、カルシウム化合物とともにマグネシウム化合物を添加し、pH8〜11のアルカリ性で反応させることによりシリカを除去することができ、シリカに起因するRO膜の閉塞を防止することができることを見出した。   As a result of intensive studies to solve the above-mentioned problems, the present inventors have determined that the amount of calcium compound added to fluoride-containing water is less than the reaction equivalent of fluoride in fluoride-containing water. It has been found that the concentration of calcium to be reduced can be reduced, and the calcium removal step with carbonate can be dispensed with. Moreover, it discovered that a silica compound could be removed by adding a magnesium compound with a calcium compound, and making it react with alkali of pH 8-11, and can block | close the RO membrane resulting from a silica.

本発明はこのような知見に基いて達成されたものであり、以下を要旨とする。   The present invention has been achieved on the basis of such findings, and the gist thereof is as follows.

[1] フッ化物含有水に、該フッ化物含有水中のカルシウム濃度が該フッ化物含有水中のフッ化物の反応当量よりもカルシウムとして5〜200mg/L不足となるようにカルシウム化合物を添加して反応させる第一工程と、該第一工程の反応液を固液分離して、前記フッ化物含有水よりもフッ化物濃度の低い分離水を得る第二工程と、該分離水を逆浸透膜処理して透過水と濃縮水とに分離する第三工程とを含むフッ化物含有水の処理方法であって、前記フッ化物含有水がシリカを含み、前記第一工程において、該シリカを含むフッ化物含有水にカルシウム化合物としてマグネシウム/カルシウム含有量比(重量比)0.002〜0.2の消石灰を添加することにより、カルシウム化合物とともにマグネシウム化合物を添加し、pH8〜11で反応させる、フッ化物含有水の処理方法。 [1] A calcium compound is added to the fluoride-containing water and reacted so that the calcium concentration in the fluoride-containing water is 5 to 200 mg / L short of calcium as the calcium than the reaction equivalent of the fluoride in the fluoride-containing water. A first step of performing a solid-liquid separation of the reaction solution of the first step to obtain a separated water having a fluoride concentration lower than that of the fluoride-containing water, and subjecting the separated water to a reverse osmosis membrane treatment A fluoride-containing water treatment method comprising a third step of separating the permeated water and the concentrated water , wherein the fluoride-containing water contains silica, and in the first step, the fluoride-containing water contains the silica. By adding slaked lime having a magnesium / calcium content ratio (weight ratio) of 0.002 to 0.2 as a calcium compound to water, the magnesium compound is added together with the calcium compound, and the pH is 8 to 11 A method of treating fluoride-containing water, which is reacted in

] 前記第三工程において、前記逆浸透膜処理に供する前記分離水をpH9〜11に調整することを特徴とする、[1]に記載のフッ化物含有水の処理方法。 [ 2 ] The method for treating fluoride-containing water according to [1 ], wherein in the third step, the separated water to be subjected to the reverse osmosis membrane treatment is adjusted to pH 9-11.

] 前記第三工程の透過水をpH5〜8に調整して、更に逆浸透膜分離して透過水と濃縮水とに分離する第四工程を含むことを特徴とする、[1]又は2]に記載のフッ化物含有水の処理方法。 [ 3 ] The method includes the fourth step of adjusting the permeated water in the third step to pH 5 to 8 and further separating the permeated water and the concentrated water by reverse osmosis membrane separation, [1] or The method for treating fluoride-containing water according to [ 2] .

] 前記第一工程の反応液を凝集処理した後前記固液分離に供し、前記カルシウム化合物は、該固液分離で得られた分離汚泥の一部との混合物として前記フッ化物含有水に添加することを特徴とする、[1]乃至[]のいずれかに記載のフッ化物含有水の処理方法。 [ 4 ] The reaction solution of the first step is subjected to agglomeration treatment and then subjected to the solid-liquid separation, and the calcium compound is mixed with the fluoride-containing water as a mixture with a part of the separated sludge obtained by the solid-liquid separation. The method for treating fluoride-containing water according to any one of [1] to [ 3 ], wherein the fluoride-containing water is added.

] 前記第二工程の分離水に鉄化合物を添加してpH5〜9で凝集処理した後固液分離し、得られた分離水を硬度成分除去処理した後、前記第三工程の逆浸透膜処理に供することを特徴とする、[1]乃至[]のいずれかに記載のフッ化物含有水の処理方法。 [ 5 ] An iron compound is added to the separated water in the second step and subjected to agglomeration treatment at pH 5 to 9, followed by solid-liquid separation. The obtained separated water is subjected to a hardness component removal treatment, and then reverse osmosis in the third step. The method for treating fluoride-containing water according to any one of [1] to [ 4 ], wherein the method is used for membrane treatment.

] フッ化物含有水に、該フッ化物含有水中のカルシウム濃度が該フッ化物含有水中のフッ化物の反応当量よりもカルシウムとして5〜200mg/L不足となるようにカルシウム化合物を添加して反応させる反応槽と、該反応槽からの反応液を固液分離して、前記フッ化物含有水よりもフッ化物濃度の低い分離水を得る固液分離手段と、該分離水を逆浸透膜処理して透過水と濃縮水とに分離する逆浸透膜分離装置(以下、「第1逆浸透膜分離装置」と称す。)とを有するフッ化物含有水の処理装置であって、前記フッ化物含有水がシリカを含み、前記反応槽において、該シリカを含むフッ化物含有水にカルシウム化合物としてマグネシウム/カルシウム含有量比(重量比)0.002〜0.2の消石灰を添加することにより、カルシウム化合物とともにマグネシウム化合物を添加し、pH8〜11で反応させる、フッ化物含有水の処理装置。 [ 6 ] A calcium compound is added to the fluoride-containing water and reacted so that the calcium concentration in the fluoride-containing water is 5 to 200 mg / L short of calcium as the calcium equivalent to the reaction equivalent of the fluoride in the fluoride-containing water. A solid-liquid separation means for obtaining a separated water having a fluoride concentration lower than that of the fluoride-containing water, and a reverse osmosis membrane treatment of the separated water. A fluoride-containing water treatment apparatus having a reverse osmosis membrane separation device (hereinafter referred to as “first reverse osmosis membrane separation device”) that separates permeated water and concentrated water. By adding slaked lime having a magnesium / calcium content ratio (weight ratio) of 0.002 to 0.2 as a calcium compound to the fluoride-containing water containing silica in the reaction vessel. With compound added magnesium compound is reacted with pH 8-11, the fluoride-containing water treatment equipment.

] 前記第1逆浸透膜分離装置に供給される前記分離水をpH9〜11とするpH調整手段を有することを特徴とする、[6]に記載のフッ化物含有水の処理装置。 [ 7 ] The treatment apparatus for fluoride-containing water according to [ 6], further comprising pH adjusting means for adjusting the separation water supplied to the first reverse osmosis membrane separation apparatus to pH 9-11.

] 前記第1逆浸透膜分離装置の透過水をpH5〜8に調整するpH調整手段と、pH調整された水を逆浸透膜分離して透過水と濃縮水に分離する第2逆浸透膜分離装置とを有することを特徴とする、[又は7]に記載のフッ化物含有水の処理装置。 [ 8 ] pH adjusting means for adjusting the permeated water of the first reverse osmosis membrane separation device to pH 5-8, and second reverse osmosis for separating the pH-adjusted water into the permeated water and the concentrated water by reverse osmosis membrane separation. The apparatus for treating fluoride-containing water according to [ 6 ] or [ 7], comprising a membrane separator.

] 前記反応槽からの反応液を凝集処理した後前記固液分離手段に送給する凝集処理手段と、該固液分離手段で得られた分離汚泥の一部をカルシウム化合物と混合する混合槽と、該混合槽の混合物を前記カルシウム化合物として前記反応槽に添加する手段とを有する、[]乃至[]のいずれかに記載のフッ化物含有水の処理装置。 [ 9 ] Aggregation treatment means for aggregating the reaction liquid from the reaction tank and then feeding to the solid-liquid separation means, and mixing for mixing a part of the separated sludge obtained by the solid-liquid separation means with a calcium compound The treatment apparatus for fluoride-containing water according to any one of [ 6 ] to [ 8 ], comprising a tank and means for adding the mixture of the mixing tank to the reaction tank as the calcium compound.

10] 前記固液分離手段で得られた分離水に鉄化合物を添加してpH5〜9で凝集処理した後、固液分離する凝集・固液分離手段と、該凝集・固液分離手段で得られた分離水を処理する硬度成分除去手段とを有し、該硬度成分除去手段の処理水が前記第1逆浸透膜分離装置に供給されることを特徴とする、[]乃至[]のいずれかに記載のフッ化物含有水の処理装置。 [ 10 ] An agglomeration / solid-liquid separation means for solid-liquid separation after adding an iron compound to the separated water obtained by the solid-liquid separation means and coagulating at pH 5-9, and the aggregation / solid-liquid separation means [ 6 ] to [ 9 ], characterized in that it has a hardness component removing means for treating the obtained separated water, and the treated water of the hardness component removing means is supplied to the first reverse osmosis membrane separation device. ] The fluoride-containing water treatment apparatus according to any one of the above.

本発明によれば、フッ化物含有水をRO膜処理して脱塩水を回収するに当たり、RO膜の閉塞を防止して安定処理を行うと共に、RO膜処理の前処理に使用する薬品量及び発生汚泥量を低減することができる。   According to the present invention, in recovering demineralized water by RO membrane treatment of fluoride-containing water, the RO membrane is prevented from being clogged and stabilized, and the amount and generation of chemicals used for the pretreatment of the RO membrane treatment The amount of sludge can be reduced.

本発明のフッ化物含有水の処理装置の実施の形態の一例を示す系統図である。It is a systematic diagram which shows an example of embodiment of the processing apparatus of the fluoride containing water of this invention. 実施例1で採用した水処理装置を示す系統図である。1 is a system diagram showing a water treatment device adopted in Example 1. FIG. 比較例1で採用した水処理装置を示す系統図である。5 is a system diagram showing a water treatment device employed in Comparative Example 1. FIG. 比較例2で採用した水処理装置を示す系統図である。5 is a system diagram showing a water treatment device employed in Comparative Example 2. FIG.

以下、図面を参照して本発明のフッ化物含有水の処理方法及び処理装置の実施の形態を詳細に説明する。   Hereinafter, embodiments of a treatment method and a treatment apparatus for fluoride-containing water according to the present invention will be described in detail with reference to the drawings.

図1は、本発明のフッ化物含有水の処理装置の実施の形態を示す系統図である。
図1において、1は第1反応槽、2は第1凝集槽、3は第1固液分離手段、4はCa反応槽(混合槽)、5は第2凝集槽、6は第2固液分離手段、7は硬度成分除去手段、8はpH調整槽、9は第1RO膜分離装置、10は第2RO膜分離装置をそれぞれ示す。
なお、本発明において、pH調整に用いる酸、アルカリとしては、通常の水処理に一般的に使用されているものを用いることができ、例えば、塩酸、硫酸などの酸、水酸化ナトリウム、水酸化カリウムなどのアルカリ金属水酸化物といったアルカリを用いることができる。
FIG. 1 is a system diagram showing an embodiment of a treatment apparatus for fluoride-containing water according to the present invention.
In FIG. 1, 1 is a first reaction tank, 2 is a first coagulation tank, 3 is a first solid-liquid separation means, 4 is a Ca reaction tank (mixing tank), 5 is a second coagulation tank, and 6 is a second solid-liquid tank. Separation means, 7 is a hardness component removal means, 8 is a pH adjustment tank, 9 is a first RO membrane separation device, and 10 is a second RO membrane separation device.
In the present invention, as the acid and alkali used for pH adjustment, those generally used for ordinary water treatment can be used. For example, acids such as hydrochloric acid and sulfuric acid, sodium hydroxide, hydroxide An alkali such as an alkali metal hydroxide such as potassium can be used.

原水(フッ化物含有水)は、第1反応槽1において、カルシウム(Ca)化合物(図1においては、Ca反応槽4からの改質汚泥)と必要に応じてマグネシウム(Mg)化合物と酸又はアルカリ(通常はアルカリ)が添加され、pH8〜11で処理されることにより、フッ化カルシウム等の不溶化物が生成する(第一工程)。   The raw water (fluoride-containing water) is a calcium (Ca) compound (modified sludge from the Ca reaction tank 4 in FIG. 1) and, if necessary, a magnesium (Mg) compound and an acid or Alkali (usually alkali) is added and treated at pH 8 to 11 to produce insolubilized materials such as calcium fluoride (first step).

第1反応槽1の処理水は、次いで第1凝集槽2で高分子凝集剤が添加されて凝集処理された後、第1固液分離手段3で固液分離される(第二工程)。固液分離された分離汚泥は系外に排出されるが、その一部は、Ca反応槽4に送給され、カルシウム化合物と混合される。分離汚泥とカルシウム化合物との混合物(改質汚泥)は、第1反応槽1に送給される。第1固液分離槽3で固液分離された分離水は第2凝集槽5に送給される。第2凝集槽5には、鉄(Fe)化合物と必要に応じて酸又はアルカリが添加されてpH5〜9に調整されて凝集処理が行なわれ、凝集処理水は第2固液分離手段6で固液分離される。   The treated water in the first reaction tank 1 is then subjected to a coagulation treatment by adding a polymer flocculant in the first coagulation tank 2 and then solid-liquid separated by the first solid-liquid separation means 3 (second step). The separated sludge separated into solid and liquid is discharged out of the system, but a part thereof is fed to the Ca reaction tank 4 and mixed with the calcium compound. A mixture (modified sludge) of separated sludge and calcium compound is fed to the first reaction tank 1. The separated water that has been solid-liquid separated in the first solid-liquid separation tank 3 is fed to the second coagulation tank 5. In the second flocculation tank 5, an iron (Fe) compound and, if necessary, an acid or an alkali are added to adjust the pH to 5 to 9, and the flocculation treatment is performed. Solid-liquid separation.

第2固液分離手段6で固液分離された分離水は、硬度成分除去手段7に導入されて、カルシウム、マグネシウムなどの硬度成分が除去される。硬度成分除去手段7で硬度成分が除去された処理水は、pH調整槽8で酸又はアルカリ(通常はアルカリ)が添加されてpH9〜11に調整される。ここで、必要に応じてスケール防止剤が添加される。pH調整槽8でpH調整された水は、第1RO分離装置9でRO膜処理され、脱塩された透過水と濃縮水とに分離される(第三工程)。
第1RO膜分離装置9で脱塩された透過水は、酸又はアルカリ(通常は酸)によりpH5〜8に調整された後、第2RO膜分離装置10で更に脱塩処理され透過水と濃縮水に分離される(第四工程)。
The separated water that has been solid-liquid separated by the second solid-liquid separation means 6 is introduced into the hardness component removal means 7 to remove hardness components such as calcium and magnesium. The treated water from which the hardness component has been removed by the hardness component removing means 7 is adjusted to pH 9 to 11 by adding acid or alkali (usually alkali) in the pH adjusting tank 8. Here, a scale inhibitor is added as necessary. The water whose pH has been adjusted in the pH adjusting tank 8 is subjected to RO membrane treatment in the first RO separation device 9 and separated into desalted permeated water and concentrated water (third step).
The permeated water desalted by the first RO membrane separation device 9 is adjusted to pH 5-8 with acid or alkali (usually acid), and then further desalted by the second RO membrane separation device 10 to be permeated water and concentrated water. (Fourth step).

第四の工程で得られた透過水は、設備用水又は超純水原水として再利用可能となる。
以下、各工程の詳細について説明する。
The permeated water obtained in the fourth step can be reused as facility water or ultrapure water.
Details of each step will be described below.

<第一工程>
第一工程では、原水(フッ化物含有水)にカルシウム化合物を添加し、下式の反応によりフッ化カルシウムを析出させる(第1反応槽1)。
Ca2+ + 2F → CaF
<First step>
In the first step, a calcium compound is added to raw water (fluoride-containing water), and calcium fluoride is precipitated by the reaction of the following formula (first reaction tank 1).
Ca 2+ + 2F → CaF 2

カルシウム化合物の添加量は、カルシウム化合物添加後の原水中のカルシウム量が、下式で算出される原水中のフッ化物の反応当量よりもカルシウムとして5〜200mg−Ca/L不足、好ましくは5〜50mg−Ca/L不足となるような添加量とする。
反応当量のカルシウム量[mg−Ca/L]=
原水のフッ素濃度[mg−F/L]×(40/38)
カルシウム化合物の添加量が上記下限よりも少ないと、フッ化物の除去を十分に行うことができず、後段のRO膜処理の給水の塩類濃度が高くなる。一方、上記上限よりも多いと、第二工程の分離水に残留するカルシウム濃度が高くなり、この場合には、炭酸塩を用いたカルシウム除去工程が必要となって、使用薬品量ならびに発生汚泥量が多くなり好ましくない。
The amount of calcium compound added is such that the amount of calcium in the raw water after addition of the calcium compound is deficient by 5 to 200 mg-Ca / L, preferably from 5 to 200 mg-Ca / L than the reaction equivalent of fluoride in the raw water calculated by the following formula: The added amount is such that 50 mg-Ca / L is insufficient.
Calcium content of reaction equivalent [mg-Ca / L] =
Fluorine concentration of raw water [mg-F / L] × (40/38)
If the amount of calcium compound added is less than the above lower limit, the fluoride cannot be sufficiently removed, and the salt concentration of the feed water for the subsequent RO membrane treatment becomes high. On the other hand, if the amount exceeds the above upper limit, the concentration of calcium remaining in the separated water in the second step becomes high. In this case, a calcium removal step using carbonate is necessary, and the amount of chemicals used and the amount of generated sludge Is undesirably increased.

通常、本発明で処理対象とする電子ディスプレイ、半導体などの電子工業分野等から排出されるフッ化物含有水のフッ素濃度は20〜1000mg−F/L、中でも150〜800mg−F/Lである。本発明では、このような原水に対して、カルシウム化合物を、カルシウム化合物添加後の原水中のカルシウム量が原水中のフッ化物の反応当量に対してカルシウムとして5〜200mg−Ca/L不足、好ましくは5〜50mg−Ca/L不足となるように添加する。   Usually, the fluorine concentration of fluoride-containing water discharged from the electronic industry such as electronic displays and semiconductors to be treated in the present invention is 20 to 1000 mg-F / L, particularly 150 to 800 mg-F / L. In the present invention, with respect to such raw water, the amount of calcium in the raw water after addition of the calcium compound is deficient in 5-200 mg-Ca / L as calcium with respect to the reaction equivalent of fluoride in the raw water, preferably Is added so as to be 5 to 50 mg-Ca / L shortage.

このような添加量でカルシウム化合物を添加した後の原水のカルシウム濃度は、原水中のフッ化物の反応当量の0.65以上1.0倍未満、好ましくは0.9以上1.0倍未満である(以下、原水中のフッ化物の反応当量に対するカルシウム濃度の比率を「反応当量比」と称す。)。   The calcium concentration of the raw water after adding the calcium compound in such an addition amount is 0.65 or more and less than 1.0 times, preferably 0.9 or more and less than 1.0 times the fluoride equivalent in the raw water. (Hereinafter, the ratio of the calcium concentration to the reaction equivalent of fluoride in raw water is referred to as “reaction equivalent ratio”.)

なお、カルシウムは原水中にも含まれる場合があるため、原水に添加されたカルシウム化合物由来のカルシウム濃度と、原水由来のカルシウム(原水に含まれているカルシウム)濃度との合計が上記のカルシウム濃度となるようにカルシウム化合物を添加する。原水中にカルシウムが殆ど含まれていない場合は、原水のフッ素濃度からカルシウム添加量を決定することができる。   In addition, since calcium may be contained in raw water, the sum of the calcium concentration derived from the calcium compound added to the raw water and the calcium concentration derived from the raw water (calcium contained in the raw water) is the above calcium concentration. Calcium compound is added so that When calcium is hardly contained in the raw water, the amount of calcium added can be determined from the fluorine concentration of the raw water.

第一工程では、カルシウム化合物とともにマグネシウム化合物を添加してpH8〜11のアルカリ性で反応させることにより、原水中のシリカとマグネシウム化合物との反応で、シリカをケイ酸マグネシウムとして除去することができる。また、原水中にリン酸が混入している場合には、下式によりリン酸とカルシウムを反応させて、リン酸をリン酸カルシウムとして析出させて、除去することができる。
10Ca2+ + 6PO 3− + 2OH → Ca10(PO(OH)
In a 1st process, a silica can be removed as magnesium silicate by reaction with the silica in a raw | natural water and a magnesium compound by adding a magnesium compound with a calcium compound, and making it react with alkaline of pH8-11. Moreover, when phosphoric acid is mixed in raw water, phosphoric acid and calcium can be made to react by the following formula, and phosphoric acid can be precipitated as calcium phosphate and removed.
10Ca 2+ + 6PO 4 3 + 2OH → Ca 10 (PO 4 ) 6 (OH) 2

第一工程における反応は好ましくはpH8〜11、より好ましくはpH9〜10.5で行われる。
また、カルシウム化合物としては、水酸化カルシウム、炭酸カルシウム、塩化カルシウムなどを用いることができ、マグネシウム化合物としては、水酸化マグネシウム、塩化マグネシウムなどを用いることができる。マグネシウム化合物を添加する場合、その添加量は、原水Si濃度に対して、Mg/Si比(重量比)=0.1〜1程度となるような量とすることが好ましい。マグネシウム化合物を併用添加する場合、マグネシウムを含有したカルシウム系薬剤を用いると、使用薬剤の種類を減らすことが出来、好ましい。このようなものとしては、例えば、水酸化カルシウム、炭酸カルシウムなどが挙げられる。特にマグネシウム/カルシウム含有量比(重量比)0.002〜0.02の消石灰を用いることが好ましい。
The reaction in the first step is preferably performed at pH 8-11, more preferably at pH 9-10.5.
In addition, calcium hydroxide, calcium carbonate, calcium chloride and the like can be used as the calcium compound, and magnesium hydroxide, magnesium chloride and the like can be used as the magnesium compound. When adding a magnesium compound, it is preferable that the amount of addition be such that the Mg / Si ratio (weight ratio) is about 0.1 to 1 with respect to the raw water Si concentration. When adding a magnesium compound in combination, the use of a calcium-based drug containing magnesium is preferable because the type of drug used can be reduced. Examples of such include calcium hydroxide and calcium carbonate. It is particularly preferable to use slaked lime having a magnesium / calcium content ratio (weight ratio) of 0.002 to 0.02.

<第二工程>
第二工程では、第一工程で析出した不溶化物(フッ化カルシウム、リン酸カルシウムケイ酸マグネシウムを含む汚泥)を固液分離して分離水を得る(第1固液分離手段3)。ここで、固液分離性を高めるために、第一工程と第二工程との間に、高分子凝集剤を添加して凝集処理する凝集工程を行っても良い(第1凝集槽2)。
この場合、高分子凝集剤としては、アニオン系高分子凝集剤、ノニオン系高分子凝集剤等の1種又は2種以上を用いることができ、その添加量は、処理対象原水の水質や用いる高分子凝集剤によっても異なるが、通常0.1〜20mg/L程度である。
<Second step>
In the second step, the insolubilized matter (sludge containing calcium fluoride and calcium phosphate magnesium silicate) precipitated in the first step is subjected to solid-liquid separation to obtain separated water (first solid-liquid separation means 3). Here, in order to improve the solid-liquid separation property, an aggregation step of adding a polymer flocculant and performing an aggregation treatment may be performed between the first step and the second step (first aggregation tank 2).
In this case, as the polymer flocculant, one or more of anionic polymer flocculant, nonionic polymer flocculant and the like can be used. Although it varies depending on the molecular flocculant, it is usually about 0.1 to 20 mg / L.

高分子凝集剤による凝集処理を行って得られた固液分離水中に高分子凝集剤が残留する場合には、図1に示すように、該分離水に無機凝集剤を添加して凝集処理した後、さらに固液分離する工程を行っても良い(第2凝集槽5、第2固液分離手段6)。分離水中に残留した高分子凝集剤は、後段のRO膜の膜閉塞を発生する原因となるため、無機凝集剤由来の金属水酸化物により残留高分子凝集剤を吸着させ、固液分離することで除去する。無機凝集剤としては、塩化第二鉄、硫酸第二鉄等の鉄化合物が好ましい。これは、無機凝集剤としてアルミニウム化合物を使用すると、分離水中のフッ化物とアルミニウムイオンが錯体を形成するため、水酸化アルミニウムが析出し難いためである。鉄化合物の添加量は、高分子凝集剤の残留量によっても異なるが、通常、Fe換算の添加量として0.5〜5mg/L程度である。   When the polymer flocculant remains in the solid-liquid separated water obtained by performing the flocculant treatment with the polymer flocculant, the inorganic flocculant is added to the separated water as shown in FIG. Thereafter, a step of further solid-liquid separation may be performed (second agglomeration tank 5, second solid-liquid separation means 6). The polymer flocculant remaining in the separated water may cause clogging of the subsequent RO membrane. Therefore, the residual polymer flocculant is adsorbed by the metal hydroxide derived from the inorganic flocculant and solid-liquid separated. Remove with. As the inorganic flocculant, iron compounds such as ferric chloride and ferric sulfate are preferable. This is because, when an aluminum compound is used as the inorganic flocculant, the fluoride in the separated water and aluminum ions form a complex, and therefore aluminum hydroxide is difficult to precipitate. The addition amount of the iron compound varies depending on the residual amount of the polymer flocculant, but is usually about 0.5 to 5 mg / L as the addition amount in terms of Fe.

この鉄化合物による凝集処理は、必要に応じて酸又はアルカリを添加してpH5〜9の範囲で行うことが、高分子凝集剤の吸着除去効率を高める上で好ましい。   The aggregation treatment with the iron compound is preferably performed in the range of pH 5 to 9 by adding an acid or alkali as necessary in order to increase the adsorption removal efficiency of the polymer flocculant.

また、第一工程における不溶化物の析出を促進させるため、図1に示すように、第1固液分離手段3で分離された分離汚泥の一部をCa反応槽4に返送し、原水に添加するカルシウム化合物と混合した後、第1反応槽1に移送するようにしても良い。この場合、分離汚泥の返送量としては、下式で表される返送比として10〜80の範囲が好ましい。
返送比=(汚泥返送流量×返送汚泥濃度)/(原水流量×原水由来発生SS濃度)
Also, in order to promote precipitation of insolubilized material in the first step, as shown in FIG. 1, a part of the separated sludge separated by the first solid-liquid separation means 3 is returned to the Ca reaction tank 4 and added to the raw water. You may make it transfer to the 1st reaction tank 1 after mixing with the calcium compound to perform. In this case, the return amount of the separated sludge is preferably in the range of 10 to 80 as the return ratio represented by the following formula.
Return ratio = (sludge return flow rate x return sludge concentration) / (raw water flow rate x raw water-derived SS concentration)

第二工程における第1固液分離手段3、第2固液分離手段6としては、沈殿槽等の固液分離槽の他、膜分離装置、濾過装置等を用いることができる。   As the 1st solid-liquid separation means 3 and the 2nd solid-liquid separation means 6 in a 2nd process, a membrane separation apparatus, a filtration apparatus, etc. other than solid-liquid separation tanks, such as a precipitation tank, can be used.

<第三工程>
第三工程では、第二工程の分離水をRO膜処理して透過水と濃縮水に分離し、脱塩された透過水を回収する(第1RO膜分離装置9)。第三工程のRO膜処理に供する分離水は、必要に応じて酸又はアルカリを添加してpH5〜12、特にpH9〜11に調整することが好ましい(pH調整槽8)。これは、RO膜処理の供給水中のフッ化物は下記反応式の通り、pH9以上で大部分がフッ化物イオンとして解離するので、RO膜におけるフッ化物除去率が高くなるためである。
HF(酸性)⇔ H + F (アルカリ性)
<Third step>
In the third step, the separation water in the second step is subjected to RO membrane treatment to separate into permeated water and concentrated water, and the desalted permeated water is recovered (first RO membrane separation device 9). It is preferable that the separated water used for the RO membrane treatment in the third step is adjusted to pH 5 to 12, particularly pH 9 to 11, by adding acid or alkali as necessary (pH adjusting tank 8). This is because most of the fluoride in the feed water for RO membrane treatment dissociates as fluoride ions at a pH of 9 or higher as shown in the following reaction formula, so that the fluoride removal rate in the RO membrane is increased.
HF (acidic) ⇔ H + + F - (alkaline)

ここで、RO膜におけるスケール生成抑制のため、第二工程の処理水を軟化塔などの硬度成分除去手段7に導入して、カルシウム、マグネシウムなどの硬度成分を除去する工程を行っても良い。また、第1RO膜分離装置9の供給水にキレート剤などのスケール防止剤を添加しても良い。   Here, in order to suppress scale formation in the RO membrane, the process of removing the hardness components such as calcium and magnesium by introducing the treated water in the second step into the hardness component removing means 7 such as a softening tower may be performed. Moreover, you may add scale inhibitors, such as a chelating agent, to the supply water of the 1st RO membrane separation apparatus 9. FIG.

<第四工程>
第四工程では、第三工程の透過水をRO膜分離して透過水と濃縮水に分離し、更に脱塩された透過水を回収する(第2RO膜分離装置10)。このRO膜処理の供給水のpHは、以下の理由からpH5〜8とすることが好ましい。即ち、原水中にアンモニアが含有されている場合、第三工程においてpH9〜11のアルカリ性で処理を行うと、RO膜でのアンモニアの除去率が低く、透過水中にアンモニアが残留する傾向となる。第四工程の供給水中に残存しているアンモニアは、pH8以下で大部分がアンモニウムイオンとして解離する。ただし、このpHを過度に低くすることは、pH調整に用いる薬剤量、後段の処理等の面で好ましくない。従って、第三工程の第1RO膜分離装置9の透過水に、必要に応じて酸又はアルカリ(通常は酸)を添加して、pH5〜8に調整することにより、第2RO膜分離装置10におけるアンモニア除去率を高くする。
<Fourth process>
In the fourth step, the permeated water in the third step is separated into RO and concentrated water, and the desalted permeated water is recovered (second RO membrane separation device 10). The pH of the feed water for this RO membrane treatment is preferably 5 to 8 for the following reasons. That is, when ammonia is contained in the raw water, if the treatment is performed with alkaline pH 9 to 11 in the third step, the removal rate of ammonia in the RO membrane is low, and ammonia tends to remain in the permeated water. Most of the ammonia remaining in the water supplied in the fourth step is dissociated as ammonium ions at pH 8 or lower. However, excessively lowering the pH is not preferable in terms of the amount of drug used for pH adjustment, the subsequent treatment, and the like. Therefore, by adding acid or alkali (usually acid) to the permeated water of the first RO membrane separation device 9 in the third step and adjusting the pH to 5-8, in the second RO membrane separation device 10 Increase the ammonia removal rate.

以下に実施例及び比較例を挙げて本発明をより具体的に説明する。
なお、以下において、原水としては、下記水質のものを用いた。この原水中のフッ化物の反応当量となるカルシウム濃度は594.7mg−Ca/Lであり、原水中のカルシウム濃度17.3mg−Ca/Lを差し引くと、原水中のフッ化物の反応当量となるためのカルシウム化合物の添加量は、577mg−Ca/Lとなる。
<原水水質>

Figure 0005692278
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
In the following, raw water having the following water quality was used. The calcium concentration that is the reaction equivalent of fluoride in the raw water is 594.7 mg-Ca / L, and subtracting the calcium concentration of 17.3 mg-Ca / L in the raw water gives the reaction equivalent of fluoride in the raw water. Therefore, the amount of calcium compound added is 777 mg-Ca / L.
<Raw water quality>
Figure 0005692278

また、カルシウム化合物としては消石灰(Ca(OH)、Mg/Ca(重量比)=0.008)を用い、pH調整用の酸としては塩酸(HCl)、アルカリとしては水酸化ナトリウム(NaOH)を用いた。また、鉄化合物としては塩化第二鉄(38%FeCl)を用いた。また、高分子凝集剤としては、栗田工業(株)製アニオン系高分子凝集剤「クリフロックPA331」を用い、スケール防止剤としてはエチレンジアミン四酢酸ナトリウム塩(EDTA)を用いた。 Further, slaked lime (Ca (OH) 2 , Mg / Ca (weight ratio) = 0.008) is used as the calcium compound, hydrochloric acid (HCl) as the acid for adjusting the pH, and sodium hydroxide (NaOH) as the alkali. Was used. Further, ferric chloride (38% FeCl 3 ) was used as the iron compound. As the polymer flocculant, an anionic polymer flocculant “Cliff Rock PA331” manufactured by Kurita Kogyo Co., Ltd. was used, and ethylenediaminetetraacetic acid sodium salt (EDTA) was used as the scale inhibitor.

[実施例1〜3]
表1に示す水質の原水を図2に示す水処理装置で処理する運転を約3週間行った。図2において、図1におけると同一機能を奏する処理部には同一符号を付してある。各処理部の仕様及び各処理部の流量等の処理条件は以下の通りとした。
[Examples 1 to 3]
The operation | movement which processes the raw | natural raw water of Table 1 with the water treatment apparatus shown in FIG. 2 was performed for about 3 weeks. In FIG. 2, processing units having the same functions as those in FIG. The processing conditions such as the specifications of each processing unit and the flow rate of each processing unit were as follows.

<第1反応槽1>
pH:10.5
HRT:20min
消石灰添加量:カルシウム換算添加量として表2に示す通り
<第1凝集槽2>
PA331添加量:1mg/L
HRT:5min
<第1沈殿槽3A>
LV:4m/h
汚泥返送比:20
<第2凝集槽5>
38%FeCl添加量:15mg/L
pH:6.5
HRT:10min
<砂濾過塔6A>
LV=10m/h
<軟化塔(イオン交換樹脂塔)7A>
樹脂:三菱化学社製 強酸性陽イオン交換樹脂「SK−1B」
SV:30h−1
<pH調整槽8>
pH:10.5
EDTA添加量:0.0025mmol/L
<第1RO膜分離装置9>
RO膜:日東電工社製 低圧芳香族ポリアミド膜「ES−20」
供給水量:100L/h
回収率:80%
<第2RO膜分離装置10>
RO膜:日東電工社製 低圧芳香族ポリアミド膜「ES−20」
供給水量:80L/h
回収率:90%
pH:7.5
<First reaction tank 1>
pH: 10.5
HRT: 20 min
Addition amount of slaked lime: As shown in Table 2 as an addition amount in terms of calcium <first flocculation tank 2>
PA331 addition amount: 1 mg / L
HRT: 5 min
<First sedimentation tank 3A>
LV: 4m / h
Sludge return ratio: 20
<Second aggregation tank 5>
38% FeCl 3 addition amount: 15 mg / L
pH: 6.5
HRT: 10 min
<Sand filtration tower 6A>
LV = 10m / h
<Softening tower (ion exchange resin tower) 7A>
Resin: Strongly acidic cation exchange resin “SK-1B” manufactured by Mitsubishi Chemical Corporation
SV: 30h -1
<PH adjustment tank 8>
pH: 10.5
EDTA addition amount: 0.0025 mmol / L
<First RO membrane separation device 9>
RO membrane: Low pressure aromatic polyamide membrane “ES-20” manufactured by Nitto Denko Corporation
Supply water volume: 100L / h
Recovery rate: 80%
<Second RO membrane separation device 10>
RO membrane: Low pressure aromatic polyamide membrane “ES-20” manufactured by Nitto Denko Corporation
Supply water volume: 80L / h
Recovery rate: 90%
pH: 7.5

[比較例1]
表1に示す水質の原水を図3に示す水処理装置で処理する運転を約3週間行った。図3において、図2におけると同一機能を奏する処理部には同一符号を付してある。各処理部の仕様及び各処理部の流量等の処理条件は以下の通りとした。
本比較例では、消石灰添加量を実施例1〜3より多くし、第1反応槽のpHを8.0とし、第1沈殿槽3Aの分離水に対してカルシウム除去工程を行う第2反応槽11、付加凝集槽12及び第2沈殿槽13を設けた点が実施例1〜3と異なり、その他の処理は実施例1〜3と同様に行った。
[Comparative Example 1]
The operation | movement which processes the raw water of the quality shown in Table 1 with the water treatment apparatus shown in FIG. 3 was performed for about 3 weeks. In FIG. 3, the same reference numerals are assigned to the processing units having the same functions as those in FIG. The processing conditions such as the specifications of each processing unit and the flow rate of each processing unit were as follows.
In this comparative example, the amount of slaked lime added is greater than in Examples 1 to 3, the pH of the first reaction tank is 8.0, and the second reaction tank in which the calcium removal step is performed on the separated water of the first precipitation tank 3A. 11, the point which provided the additional coagulation tank 12 and the 2nd sedimentation tank 13 differed from Examples 1-3, and the other process was performed similarly to Examples 1-3.

<第1反応槽1>
pH:8.0
HRT:20min
消石灰添加量:カルシウム換算添加量として表2に示す通り
<第1凝集槽2>
PA331添加量:1mg/L
HRT:5min
<第1沈殿槽3A>
LV:4m/h
汚泥返送比:20
<第2反応槽11>
NaCO添加量:1000mg/L
38%FeCl添加量:15mg/L
pH:9.0
HRT:10min
<付加凝集槽12>
PA331添加量:1mg/L
HRT:5min
<第2沈殿槽13>
LV:4m/h
<第2凝集槽5>
38%FeCl添加量:15mg/L
pH:6.5
HRT:10min
<砂濾過塔6A>
LV=10m/h
<軟化塔(イオン交換樹脂塔)7A>
樹脂:三菱化学社製 強酸性陽イオン交換樹脂「SK−1B」
SV:30h−1
<pH調整槽8>
pH:10.5
EDTA添加量:0.0025mmol/L
<第1RO膜分離装置9>
RO膜:日東電工社製 低圧芳香族ポリアミド膜「ES−20」
供給水量:100L/h
回収率:80%
<第2RO膜分離装置10>
RO膜:日東電工社製 低圧芳香族ポリアミド膜「ES−20」
供給水量:80L/h
回収率:90%
pH:7.5
<First reaction tank 1>
pH: 8.0
HRT: 20 min
Addition amount of slaked lime: As shown in Table 2 as an addition amount in terms of calcium <first flocculation tank 2>
PA331 addition amount: 1 mg / L
HRT: 5 min
<First sedimentation tank 3A>
LV: 4m / h
Sludge return ratio: 20
<Second reaction tank 11>
Na 2 CO 3 addition amount: 1000 mg / L
38% FeCl 3 addition amount: 15 mg / L
pH: 9.0
HRT: 10 min
<Additional coagulation tank 12>
PA331 addition amount: 1 mg / L
HRT: 5 min
<Second sedimentation tank 13>
LV: 4m / h
<Second aggregation tank 5>
38% FeCl 3 addition amount: 15 mg / L
pH: 6.5
HRT: 10 min
<Sand filtration tower 6A>
LV = 10m / h
<Softening tower (ion exchange resin tower) 7A>
Resin: Strongly acidic cation exchange resin “SK-1B” manufactured by Mitsubishi Chemical Corporation
SV: 30h -1
<PH adjustment tank 8>
pH: 10.5
EDTA addition amount: 0.0025 mmol / L
<First RO membrane separation device 9>
RO membrane: Low pressure aromatic polyamide membrane “ES-20” manufactured by Nitto Denko Corporation
Supply water volume: 100L / h
Recovery rate: 80%
<Second RO membrane separation device 10>
RO membrane: Low pressure aromatic polyamide membrane “ES-20” manufactured by Nitto Denko Corporation
Supply water volume: 80L / h
Recovery rate: 90%
pH: 7.5

[比較例2]
表1に示す水質の原水を図4に示す水処理装置で処理する運転を行った。図4において、図2におけると同一機能を奏する処理部には同一符号を付してある。各処理部の仕様及び各処理部の流量等の処理条件は以下の通りとした。
この比較例2は、第1反応槽1、第1凝集槽2、第1沈殿槽3A、Ca反応槽4、及び第2RO膜分離装置10を省略したこと以外は実施例1〜3と同様の条件で処理を行ったが、膜フラックスが急激に低下し、運転開始から5日後に運転不能となった。
[Comparative Example 2]
The operation | movement which processes the raw water of the quality shown in Table 1 with the water treatment apparatus shown in FIG. 4 was performed. In FIG. 4, the processing units having the same functions as those in FIG. 2 are denoted by the same reference numerals. The processing conditions such as the specifications of each processing unit and the flow rate of each processing unit were as follows.
This comparative example 2 is the same as the examples 1 to 3 except that the first reaction tank 1, the first coagulation tank 2, the first precipitation tank 3A, the Ca reaction tank 4, and the second RO membrane separation device 10 are omitted. Although the treatment was performed under the conditions, the membrane flux rapidly decreased, and the operation became impossible after 5 days from the start of operation.

<第2凝集槽5>
38%FeCl添加量:15mg/L
pH:6.5
HRT:5min
<砂濾過塔6A>
LV=10m/h
<軟化塔(イオン交換樹脂塔)7A>
樹脂:三菱化学社製 強酸性陽イオン交換樹脂「SK−1B」
SV:30h−1
<pH調整槽8>
pH:10.5
EDTA添加量:0.0025mmol/L
<第1RO膜分離装置9>
RO膜:日東電工社製 低圧芳香族ポリアミド膜「ES−20」
供給水量:100L/h
回収率:80%
<Second aggregation tank 5>
38% FeCl 3 addition amount: 15 mg / L
pH: 6.5
HRT: 5 min
<Sand filtration tower 6A>
LV = 10m / h
<Softening tower (ion exchange resin tower) 7A>
Resin: Strongly acidic cation exchange resin “SK-1B” manufactured by Mitsubishi Chemical Corporation
SV: 30h -1
<PH adjustment tank 8>
pH: 10.5
EDTA addition amount: 0.0025 mmol / L
<First RO membrane separation device 9>
RO membrane: Low pressure aromatic polyamide membrane “ES-20” manufactured by Nitto Denko Corporation
Supply water volume: 100L / h
Recovery rate: 80%

以上の実施例1〜3及び比較例1,2における砂濾過処理水、第1RO膜分離装置及び第2RO膜分離装置の透過水の水質、第1RO膜分離装置の膜フラックスの低下率(運転開始時の膜フラックスに対する低下率)、並びに原水流量当たりの発生汚泥量を表2に示す。ただし、ここでは、RO膜分離装置の濃縮水のフッ素をカルシウムで処理した場合に生成する汚泥も考慮した発生汚泥量とした。   Sand filtration treated water in the above Examples 1 to 3 and Comparative Examples 1 and 2, water quality of permeated water of the first RO membrane separator and second RO membrane separator, rate of decrease in membrane flux of the first RO membrane separator (operation start) Table 2 shows the rate of decrease with respect to the membrane flux at the time) and the amount of generated sludge per raw water flow rate. However, here, the amount of generated sludge was taken into account the sludge generated when the fluorine of the concentrated water of the RO membrane separator was treated with calcium.

Figure 0005692278
Figure 0005692278

表2より明らかなように、本発明によれば、RO膜での膜フラックスの低下を防止して長期にわたり膜フラックスを高く維持することができる。これに対して、比較例1では、膜フラックスの低下を抑制できるものの、カルシウム化合物の添加量が多いため、炭酸塩によるカルシウム除去工程を必要とし、薬品使用量が多く、発生汚泥量も多い。この比較例1に対して、実施例1〜3では、薬品使用量、発生汚泥量の低減が可能である。また、比較例2では、負の電荷を有するSi(OH)と正の電荷を有するAl(OH)がRO膜に吸着、堆層することによる膜閉塞で膜フラックスが早期に低下し、運転を継続することができなくなった。 As is apparent from Table 2, according to the present invention, it is possible to prevent the membrane flux from decreasing in the RO membrane and maintain the membrane flux high over a long period of time. On the other hand, although the fall of a membrane flux can be suppressed in the comparative example 1, since there is much addition amount of a calcium compound, the calcium removal process by carbonate is required, there are many chemical usages and the amount of generated sludge is also large. In contrast to this comparative example 1, in Examples 1 to 3, the amount of chemical used and the amount of generated sludge can be reduced. Further, in Comparative Example 2, membrane flux is reduced early due to membrane clogging due to adsorption and deposition of negatively charged Si (OH) 3 O and positively charged Al (OH) 3 on the RO membrane. I was unable to continue driving.

1 第1反応槽
2 第1凝集槽
3 第1固液分離手段
3A 第1沈殿槽
4 Ca反応槽
5 第2凝集槽
6 第2固液分離手段
6A 砂濾過塔
7 硬度成分除去手段
7A 硬化塔
8 pH調整槽
9 第1RO膜分離装置
10 第2RO膜分離装置
DESCRIPTION OF SYMBOLS 1 1st reaction tank 2 1st coagulation tank 3 1st solid-liquid separation means 3A 1st sedimentation tank 4 Ca reaction tank 5 2nd coagulation tank 6 2nd solid-liquid separation means 6A Sand filtration tower 7 Hardness component removal means 7A Curing tower 8 pH adjustment tank 9 1st RO membrane separation device 10 2nd RO membrane separation device

Claims (10)

フッ化物含有水に、該フッ化物含有水中のカルシウム濃度が該フッ化物含有水中のフッ化物の反応当量よりもカルシウムとして5〜200mg/L不足となるようにカルシウム化合物を添加して反応させる第一工程と、
該第一工程の反応液を固液分離して、前記フッ化物含有水よりもフッ化物濃度の低い分離水を得る第二工程と、
該分離水を逆浸透膜処理して透過水と濃縮水とに分離する第三工程とを含むフッ化物含有水の処理方法であって、
前記フッ化物含有水がシリカを含み、前記第一工程において、該シリカを含むフッ化物含有水にカルシウム化合物としてマグネシウム/カルシウム含有量比(重量比)0.002〜0.2の消石灰を添加することにより、カルシウム化合物とともにマグネシウム化合物を添加し、pH8〜11で反応させる、フッ化物含有水の処理方法。
First, a calcium compound is added to the fluoride-containing water and reacted so that the calcium concentration in the fluoride-containing water is 5 to 200 mg / L less than the reaction equivalent of the fluoride in the fluoride-containing water as calcium. Process,
A second step of solid-liquid separation of the reaction solution of the first step to obtain separated water having a fluoride concentration lower than that of the fluoride-containing water;
A method for treating fluoride-containing water, comprising a third step of separating the separated water into a permeated water and a concentrated water by subjecting the separated water to a reverse osmosis membrane ,
The fluoride-containing water contains silica, and in the first step, slaked lime having a magnesium / calcium content ratio (weight ratio) of 0.002 to 0.2 is added as a calcium compound to the fluoride-containing water containing silica. The processing method of the fluoride containing water which adds a magnesium compound with a calcium compound and makes it react by pH 8-11 .
前記第三工程において、前記逆浸透膜処理に供する前記分離水をpH9〜11に調整することを特徴とする、請求項1に記載のフッ化物含有水の処理方法。 2. The method for treating fluoride-containing water according to claim 1, wherein in the third step, the separated water to be subjected to the reverse osmosis membrane treatment is adjusted to pH 9-11. 前記第三工程の透過水をpH5〜8に調整して、更に逆浸透膜分離して透過水と濃縮水とに分離する第四工程を含むことを特徴とする、請求項1又は2に記載のフッ化物含有水の処理方法。 Adjust the permeate of the third step to pH 5-8, characterized in that it comprises a fourth step of separating into a transmitted water and concentrated water by reverse osmosis membrane separation Further, according to claim 1 or 2 Method for treating fluoride-containing water. 前記第一工程の反応液を凝集処理した後前記固液分離に供し、前記カルシウム化合物は、該固液分離で得られた分離汚泥の一部との混合物として前記フッ化物含有水に添加することを特徴とする、請求項1乃至のいずれか1項に記載のフッ化物含有水の処理方法。 The reaction solution of the first step is subjected to agglomeration treatment and then subjected to solid-liquid separation, and the calcium compound is added to the fluoride-containing water as a mixture with a part of the separated sludge obtained by the solid-liquid separation. The method for treating fluoride-containing water according to any one of claims 1 to 3 , wherein: 前記第二工程の分離水に鉄化合物を添加してpH5〜9で凝集処理した後固液分離し、得られた分離水を硬度成分除去処理した後、前記第三工程の逆浸透膜処理に供することを特徴とする、請求項1乃至のいずれか1項に記載のフッ化物含有水の処理方法。 After adding an iron compound to the separated water in the second step and subjecting it to a coagulation treatment at a pH of 5 to 9, solid-liquid separation is performed. After removing the hardness component from the obtained separated water, the reverse osmosis membrane treatment in the third step is performed. The method for treating fluoride-containing water according to any one of claims 1 to 4 , wherein the method comprises treating the fluoride-containing water. フッ化物含有水に、該フッ化物含有水中のカルシウム濃度が該フッ化物含有水中のフッ化物の反応当量よりもカルシウムとして5〜200mg/L不足となるようにカルシウム化合物を添加して反応させる反応槽と、
該反応槽からの反応液を固液分離して、前記フッ化物含有水よりもフッ化物濃度の低い分離水を得る固液分離手段と、
該分離水を逆浸透膜処理して透過水と濃縮水とに分離する逆浸透膜分離装置(以下、「第1逆浸透膜分離装置」と称す。)とを有するフッ化物含有水の処理装置であって、
前記フッ化物含有水がシリカを含み、前記反応槽において、該シリカを含むフッ化物含有水にカルシウム化合物としてマグネシウム/カルシウム含有量比(重量比)0.002〜0.2の消石灰を添加することにより、カルシウム化合物とともにマグネシウム化合物を添加し、pH8〜11で反応させる、フッ化物含有水の処理装置。
A reaction tank in which a calcium compound is added to and reacted with fluoride-containing water so that the calcium concentration in the fluoride-containing water is 5 to 200 mg / L short of calcium as the calcium equivalent to the reaction equivalent of fluoride in the fluoride-containing water. When,
A solid-liquid separation means for solid-liquid separation of the reaction liquid from the reaction tank to obtain separated water having a fluoride concentration lower than that of the fluoride-containing water;
A treatment apparatus for fluoride-containing water having a reverse osmosis membrane separation device (hereinafter referred to as “first reverse osmosis membrane separation device”) that separates the separated water into a permeated water and a concentrated water by subjecting the separated water to a reverse osmosis membrane treatment. Because
The fluoride-containing water contains silica, and in the reaction vessel, slaked lime having a magnesium / calcium content ratio (weight ratio) of 0.002 to 0.2 is added to the fluoride-containing water containing silica as a calcium compound. The treatment apparatus of fluoride containing water which adds a magnesium compound with calcium compound and makes it react by pH 8-11 .
前記第1逆浸透膜分離装置に供給される前記分離水をpH9〜11とするpH調整手段を有することを特徴とする、請求項に記載のフッ化物含有水の処理装置。 The apparatus for treating fluoride-containing water according to claim 6 , further comprising pH adjusting means for adjusting the pH of the separated water supplied to the first reverse osmosis membrane separator to pH 9-11. 前記第1逆浸透膜分離装置の透過水をpH5〜8に調整するpH調整手段と、pH調整された水を逆浸透膜分離して透過水と濃縮水に分離する第2逆浸透膜分離装置とを有することを特徴とする、請求項6又は7に記載のフッ化物含有水の処理装置。 PH adjusting means for adjusting the permeate of the first reverse osmosis membrane separator to pH 5-8, and a second reverse osmosis membrane separator for separating the pH-adjusted water into reverse osmosis membrane and separating it into permeate and concentrated water The apparatus for treating fluoride-containing water according to claim 6 or 7 , characterized by comprising: 前記反応槽からの反応液を凝集処理した後前記固液分離手段に送給する凝集処理手段と、該固液分離手段で得られた分離汚泥の一部をカルシウム化合物と混合する混合槽と、該混合槽の混合物を前記カルシウム化合物として前記反応槽に添加する手段とを有する、請求項乃至のいずれか1項に記載のフッ化物含有水の処理装置。 A coagulation treatment means for coagulating the reaction liquid from the reaction tank and then feeding to the solid-liquid separation means; a mixing tank for mixing a part of the separated sludge obtained by the solid-liquid separation means with a calcium compound; The apparatus for treating fluoride-containing water according to any one of claims 6 to 8 , further comprising means for adding the mixture in the mixing tank to the reaction tank as the calcium compound. 前記固液分離手段で得られた分離水に鉄化合物を添加してpH5〜9で凝集処理した後、固液分離する凝集・固液分離手段と、該凝集・固液分離手段で得られた分離水を処理する硬度成分除去手段とを有し、該硬度成分除去手段の処理水が前記第1逆浸透膜分離装置に供給されることを特徴とする、請求項乃至のいずれか1項に記載のフッ化物含有水の処理装置。 An iron compound was added to the separated water obtained by the solid-liquid separation means, and after agglomeration treatment at pH 5-9, the solid-liquid separation means for solid-liquid separation, and the aggregation-solid-liquid separation means obtained and a hardness component removing means for processing the separated water, wherein the treated water the hardness component removal means is supplied to the first reverse osmosis membrane separation device, any one of claims 6-9 1 The apparatus for treating fluoride-containing water according to Item.
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JP5665002B2 (en) * 2010-12-20 2015-02-04 株式会社日立製作所 Treatment method for fluorine-containing wastewater
JP2013208599A (en) * 2012-03-30 2013-10-10 Kurita Water Ind Ltd Apparatus for treating wastewater by high density sludge method

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