JP2004121948A - Fluorine or phosphorus removing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently remove fluorine or phosphorus from fluorine or phosphorus-containing water. <P>SOLUTION: ZrO is added to fluorine-containing water in a zirconyl reaction tank 10 to insolubilize fluorine. Next, a polymeric flocculant having a sulfone group is added to the treated water from the zirconyl reaction tank 10 in a flocculation tank 12 to form flocs. Then, the treated water from the flocculation tank 12 is subjected to solid-liquid separation treatment in a sedimentation tank 14 to efficiently remove fluorine or phosphorus from fluorine or phosphotus-containing water. <P>COPYRIGHT: (C)2004,JPO

Description

に示されるような２−アクリルアミド−２−メチルプロパンスルホン酸もしくはその塩が導入されたものであってもよい。
【００１４】
また、上記本発明の前記高分子凝集剤がアクリルアミドと２−アクリルアミド−２−メチルプロパンスルホン酸もしくはその塩の共重合物、または、アクリルアミドと２−アクリルアミド−２−メチルプロパンスルホン酸もしくはその塩とアクリル酸もしくはその塩の共重合物であってもよい。
【００１５】
このように、本発明では、希土類金属、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｔａの金属の水溶性化合物をフッ素またはリンの不溶化剤として添加する。これらの金属は、フッ素リンに対しほぼ反応式当量の添加量で反応しフッ素やリンを不溶化することができる。従って、その添加量が少なく、発生汚泥量も少なくなる。さらに、反応生成物が水和物になり水を取り込む可能性が少なく発生汚泥の脱水性がよくなる。従って、汚泥発生量を少なくでき、汚泥処分費を低減することができる。
【００１６】
しかし、希土類等の水溶性金属化合物がフッ素やリンを不溶化させるのに適しているｐＨ３〜７において、そのフロックは微細なものになりやすく、沈殿分離などによって、固液分離が十分にできないという問題がある。そこで、高分子凝集剤を添加し、微細フロックを凝集することが考えられる。ところが、安価なために汎用的に用いられている高分子凝集剤であるアクリル酸またはその塩とアクリルアミドの共重合物であるアニオン系高分子凝集剤では、ｐＨ３〜５．５においては十分な凝集が得られない。また、ｐＨ３〜７の範囲で凝集効果のあるものとしてノニオン系高分子凝集剤とカチオン系凝集剤があるが、前者は凝集力が弱いため十分な凝集効果が得られず、後者は比較的分子量が小さく、フロックが粗大化し難いため、固液分離が十分にできないという問題がある。
【００１７】
一方、本発明で用いる高分子凝集剤は、スルホン基を有しているアニオン系高分子凝集剤である。この高分子凝集剤は、上記ｐＨ範囲において、十分凝集力を有し、希土類金属、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｔａの水溶性化合物がフッ素やリンを不溶化させて生じた微細なフロックを凝集粗大化する。このため、凝集フロックを沈殿槽などで容易に固液分離することができ、微細フロックが処理水中にリークして処理水のフッ素やリンの濃度が上昇することを防止することができる。その結果、例えば、フッ素ならば濃度を数ｍｇ／Ｌ以下に確実の処理することができ、フッ素またはリンの除去が効率的に行える。
【００１８】
【発明の実施の形態】
以下、本発明の実施の形態（以下実施形態という）について、図面に基づいて説明する。尚、本実施形態は本発明の実施に関しての好ましい一例であって、本発明は本実施形態に限定されるものではない。また、本実施形態では、フッ素またはリン含有水としてフッ素含有排水を用い、フッ素またはリンの不溶化剤としてＺｒＯ塩（好ましくはＺｒＯＣｌ_２である。）の水溶性化合物、高分子凝集剤として２−アクリルアミド−２−メチルプロパンスルホン酸もしくはその塩（ＡＭＰＳ）を導入したものを用いている。
【００１９】
「実施形態１」
図１は、本発明に係るフッ素またはリン除去剤を用いた除去処理方法の実施形態１を示す図である。フッ酸などのフッ素を含有する原水は、ジルコニル反応槽１０に導入される。このジルコニル反応槽１０には、ＺｒＯの水溶性化合物（例えば、ＺｒＯＣｌ_２）を含んだ水溶液が供給されるとともに水酸化ナトリウムなどのｐＨ調整剤（原水のｐＨを下げる場合には酸、上げる場合にはアルカリ）が供給される。水酸化ナトリウム等によって、ジルコニル反応槽１０内のｐＨを３〜７、好ましくは４〜６、の範囲に調整する。これによって、ジルコニル反応槽１０では、フッ素がＺｒＯ^２−と反応し、ＺｒＯＦ_２となって不溶化する。
【００２０】
すなわち、
【化３】
ＺｒＯＣｌ_２＋２Ｆ⁻→ＺｒＯＦ_２＋２Ｃｌ⁻
という反応によって、フッ素が不溶化される。
【００２１】
本実施形態におけるジルコニル反応槽１０では、本実施形態で用いたＺｒＯ以外にも、金属の水溶性化合物として、ジルコニウムＺｒ、チタンＴｉ、ハフニウムＨｆ、バナジウムＶ、ニオブＮｂ、タンタルＴａの化合物として、塩化物、硫酸塩、硝酸塩、塩化酸化物、硫酸酸化物等が使用できる。また、希土類金属の化合物としては、スカンジウムＳｃ、イットリウムＹおよびランタノイドのランタンＬａ、セリウムＣｅ、プラセオジムＰｒ、ネオジムＮｄ、プロメチウムＰｍ、サマリウムＳｍ、ユウロピウムＥｕ、ガドリニウムＧｄ、テルビウムＴｂ、ジスプロシウムＤｙ、ホルミウムＨｏ、エルビウムＥｒ、ツリウムＴｍ、イッテルビウムＹｂ、ルテチウムＬｕの塩化物、硫酸塩、硝酸塩も使用できる。また、ジルコニル反応槽１０内はこれらが反応するのに最適なｐＨ３〜７の範囲内にする必要があるが、ｐＨ４〜６の範囲内が特に好適である。
【００２２】
次に、ジルコニル反応槽１０の処理水は、凝集槽１２に供給される。この凝集槽１２には、高分子凝集剤が供給され、ジルコニル反応槽１０で生成したフッ素の不溶化物が凝集粗大化される。
【００２３】
ここで、高分子凝集剤は、スルホン基を有するものが採用される。本実施形態では、スルホン基を有する高分子凝集剤として、下記化学式
【化４】

に示されるような２−アクリルアミド−２−メチルプロパンスルホン酸もしくはその塩（ＡＭＰＳ）を導入したものを採用している。この高分子凝集剤は、アクリルアミドと２−アクリルアミド−２−メチルプロパンスルホン酸もしくはその塩の共重合物、または、アクリルアミドと２−アクリルアミド−２−メチルプロパンスルホン酸もしくはその塩とアクリル酸もしくはその塩の共重合物であってもよい。また、この高分子凝集剤の分子量は特に限定されないが、より好ましくは５００万〜２０００万の範囲である。また、これら高分子凝集剤は、単独で又は混合物として用いることができる。さらに、これらの高分子凝集剤の添加量は任意に設定してよいが、凝集沈殿効果と経済性のバランスにより、好ましくは添加量が１〜１００ｍｇ／リットル（Ｌ）の範囲である。
【００２４】
また、本実施形態で高分子凝集剤を添加する前に、無機凝集剤を添加することもできる。無機凝集剤としては、例えば硫酸第一鉄、硫酸第二鉄、ポリ硫酸鉄、塩化第一鉄、塩化第二鉄、ポリ塩化アルミニウム、硫酸アルミニウム（硫酸バンド）、塩化アルミニウム等の多価金属塩等を用いてもよい。より好ましい凝集剤は塩化第二鉄やポリ硫酸鉄である。これら無機凝集剤は、単独もしくは混合物として用いてもよい。
【００２５】
さらに、凝集槽１２からの凝集処理水は、沈殿槽１４に導入され、ここで固形物が沈殿分離される。すなわち、上述したフッ素を不溶化したＺｒＯＦ_２の高分子凝集剤（ＡＭＰＳ）を導入したものによる凝集物が沈殿分離され、上澄み液としてフッ素濃度の低い処理水が得られる。
【００２６】
なお、凝集物を固液分離手段としては、沈殿槽１４に限定されることなく、各種の装置を利用することができる。浮上分離、遠心分離、振動ふるい、膜分離等であってもよい。特に、膜分離装置は、固形物の分離能力に優れており、好適である。
【００２７】
また、上述の金属の水溶性化合物、高分子凝集剤、無機凝集剤、ｐＨ調整剤、カルシウム塩などの各薬剤の種類や添加量、各槽における攪拌条件などは、最適となるように設計するとよい。例えば、各薬剤の種類、添加量及び各槽における攪拌条件を変化させたジャーテストを行ない、生じる凝集物のフロック径、固液分離性、発生汚泥量から決定される。
【００２８】
「実施形態２」
図２は、本発明に係るフッ素またはリン除去剤を用いた除去処理方法の実施形態２を示す図である。この実施形態２は、フッ素を高濃度で含有する排水に好適な構成である。すなわち、経済的観点から、本実施形態の希土類金属などを添加する処理は、フッ素濃度が低減された（好ましくは２０ｍｇ／Ｌ以下の）原水に適用することが好ましい。一方、エレクトロニクス産業排水などでは、フッ素濃度として、１００〜２０００ｍｇ／Ｌ程度である場合も多い。このような場合には、従来のカルシウム塩によるフッ素処理を行った後、残留するフッ素を本実施形態の実施形態１に示した処理によって除去することが好適である。
【００２９】
フッ素を高濃度で含有する原水は、まずカルシウム反応槽２０に導入される。このカルシウム反応槽２０には、消石灰や塩化カルシウムなどのカルシウム塩が供給される。なお、必要な場合には、水酸化ナトリウムなどのｐＨ調整剤も必要に応じて添加され、ｐＨがフッ化カルシウムの析出に適切なｐＨ（４〜１１程度）に調整される。カルシウム反応槽２０の処理水へのカルシウム塩添加量は、フッ素濃度を低減できれば良く、従来のフッ素処理以下の添加量でよい。
【００３０】
カルシウム反応槽２０において、カルシウム塩を添加しフッ化カルシウムを生成した後、そのままジルコニル反応槽１０に導入し、ＺｒＯＣｌ_２の水溶液を添加し残留するフッ素を不溶化する。ジルコニル反応槽１０、凝集槽１２、沈殿槽１４により上述のようにして処理される。このような処理によって、フッ素を低濃度にまで処理することができ、かつカルシウム塩や無機・有機凝集剤の添加量を比較的少なくすることができる。また、ＺｒＯ塩の添加量も比較的少なくてよい。なお、この処理においても、必要に応じて無機凝集剤を添加してもよい。
【００３１】
「その他」
上述の説明は、フッ素含有水の処理のみを対象とした。しかし、希土類金属、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｔａのうち、少なくとも１種以上からなる金属の水溶性化合物は、リンに対しても、フッ素と同様の不溶化反応を起こす。そこで、上述の処理をそのままリン含有水に適用することができる。なお、リンは、リン酸カルシウムとして除去できるため、カルシウム塩を添加する処理もそのままリン含有水に適用することができ、例えば次の反応によりリンが不溶化される。なお、リンの形態はｐＨ等によって変化する。
【化５】
ＺｒＯＣｌ_２＋２Ｈ_２ＰＯ_４ ⁻→ＺｒＯ（Ｈ_２ＰＯ_４）_２＋２Ｃｌ⁻
ＺｒＯＣｌ_２＋ＨＰＯ_４ ^２−→ＺｒＯＨＰＯ_４＋２Ｃｌ⁻
【００３２】
さらに、本発明は、フッ素とリンの両方を含有する水にも好適に適用できる。この場合、フッ素とリンに対し各当量の合計以上の希土類金属塩等を添加すればよい。
【００３３】
【実施例】
「実験１」
次に、本発明の高分子凝集剤を使用して、実施形態１に対応するフッ素含有水の処理実験を行った。フッ化ナトリウムを純水に溶解して、フッ素濃度２０ｍｇ−Ｆ／Ｌとなるようにしたものを調製し、原水とした。フッ素の不溶化剤としてジルコニウム含有率１０％の塩化酸化ジルコニウム水溶液を、原水に５０ｍｇ−Ｚｒ／Ｌとなるように添加した。さらにｐＨ調整剤としてＮａＯＨを添加し、ｐＨ５に調整した。３０分間撹拌することで、十分にフッ素とジルコニウム塩を反応させ、不溶化物を生成させた。
【００３４】
その後、高分子凝集剤を原水に１ｍｇ／Ｌとなるように添加して、さらに１０分間撹拌し、十分に高分子凝集剤により、生成した不溶化物を凝集させた。３０分間静置し、凝集物が十分に沈殿した後の上澄み液を処理水として採取し、処理水のフッ素濃度を測定した。高分子凝集剤としては、表１に示される３種類を用いた。いずれもアニオン系高分子凝集剤（オルガノ（株）製）であり、これらのうち２−アクリルアミド−２−メチルプロパンスルホン酸が導入されているものはＯＡ−３４（商品名）のみである。処理水中のフッ素濃度の結果を表１に示す。
【表１】

【００３５】
このように、比較例１、２で示される従来のアニオン系高分子凝集剤を用いた処理水は、いずれも３．５ｍｇ−Ｆ／Ｌ以上であるのに対し、実施形態のＯＡ−３４（商品名）では０．７ｍｇ−Ｆ／Ｌと比較例に対し１／５倍以下にまで処理水中のフッ素濃度を低減できていることがわかる。処理水を目視すると比較例１，２は微細なフロックが見られ、白濁していたが、実施形態では処理水の上澄み液が透明であった。これは、実施形態ではフロックが沈殿槽において沈降しやすく、沈殿槽からフッ素含有物がリークしにくくなるため、処理水のフッ素を従来と比べより低減できたためと考えられる。
【００３６】
「実験２」
さらに、本発明の高分子凝集剤を使用して、実施形態２に対応するフッ素含有水の処理実験を行った。フッ化ナトリウムを純水に溶解して、フッ素濃度２００ｍｇ−Ｆ／Ｌとなるようにしたものを調製し、原水とした。原水にフッ化カルシウムを生成させるためにカルシウム塩として消石灰を１０００ｍｇ／Ｌ添加した後、ｐＨ調整剤としてＨＣｌを添加し、ｐＨ１０に調整した。３０分間撹拌することで、十分にフッ素と消石灰を反応させ、フッ化カルシウムを生成させた。
【００３７】
その後、フッ素の不溶化剤としてセリウム含有率１０％の塩化セリウム水溶液を原水に５０ｍｇ−Ｃｅ／Ｌとなるように添加した。さらにｐＨ調整剤としてＮａＯＨを添加し、ｐＨ５に調整した。さらに３０分間撹拌することで、十分にフッ素とセリウム塩を反応させ、不溶化物を生成させた。その後、高分子凝集剤を原水に１ｍｇ／Ｌとなるように添加して、さらに１０分間撹拌し、十分に高分子凝集剤により、生成した不溶化物を凝集させた。３０分間静置し、凝集物が十分に沈殿した後の上澄み液を処理水として採取し、処理水のフッ素濃度を測定した。高分子凝集剤としては、表１と同じ３種類を用いた。いずれもアニオン系高分子凝集剤（オルガノ（株）製）であり、これらのうち２−アクリルアミド−２−メチルプロパンスルホン酸が導入されているのはＯＡ−３４（商品名）のみである。処理水中のフッ素濃度の結果を表２に示す。
【表２】

【００３８】
このように、比較例１、２で示される従来のアニオン系高分子凝集剤を用いた処理水は、いずれも５ｍｇ−Ｆ／Ｌ以上であるのに対し、実施形態のＯＡ−３４（商品名）では０．８ｍｇ−Ｆ／Ｌと比較例に対し１／５倍以下にまで処理水中のフッ素濃度を低減できていることがわかる。処理水を目視すると比較例１，２は対応する実験１の結果よりも、微細なフロックが多量に見られ、強く白濁していたが、実施形態では処理水の上澄み液が透明であった。これは、実験１の結果と同様に、実施形態ではフロックが沈殿槽において沈降しやすく、沈殿槽からフッ素含有物質がリークしにくくなるため、処理水のフッ素を従来と比べより低減できたためと考えられる。
【００３９】
上述のように、アニオン高分子凝集剤として、ＡＭＰＳが導入されているものを使用して好適な希土類金属塩等のフッ素またはリンの不溶化物を効果的に凝集できる。
【００４０】
【発明の効果】
以上説明したように、本発明においては、高分子凝集剤として、スルホン基を有する高分子凝集剤を使用する。この高分子凝集剤は、希土類金属、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｔａの水溶性化合物がフッ素やリンを不溶化させるのに好適なｐＨ３〜７において、十分凝集力を有し、希土類金属、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｔａの水溶性化合物がフッ素やリンを不溶化させて生じた微細なフロックを凝集粗大化する。このため、凝集フロックを沈殿槽などで容易に固液分離することができ、微細フロックが処理水中にリークして処理水のフッ素やリン濃度が上昇することを防止することができる。その結果、例えば、フッ素ならば濃度を確実に数ｍｇ／Ｌ以下に処理することができ、フッ素またはリンの除去が効率的に行える。
【図面の簡単な説明】
【図１】実施形態１の構成を示す図である。
【図２】実施形態２の構成を示す図である。
【符号の説明】
１０　反応槽、１２　凝集槽、１４　沈殿槽、２０　カルシウム反応槽。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for removing fluorine or phosphorus from water containing fluorine or phosphorus.
[0002]
[Prior art]
In the electronics industry that manufactures semiconductors, liquid crystals, and the like, fluorine is used in the manufacturing process, and thus the wastewater in the electronics industry often contains fluorine. As a method for removing the fluorine discharged from the fluorine-containing water, a calcium salt is added to raw water to precipitate fine particles of calcium fluoride, and these fine particles are made of an Al, Fe-based inorganic coagulant or A method of coagulating with a molecular coagulant and separating by precipitation is employed. According to this method, the amount of treated water fluorine can be reduced to 10 to 20 mg / l. However, in Japan, the emission standard for fluorine was increased from 15 mg / l to 8 mg / l in July 2001, and it became necessary to further treat fluorine.
[0003]
As a method of treating fluorine to a high degree, a method of increasing the amount of an aggregating agent added in the above-mentioned coagulation precipitation, or performing another coagulation precipitation again in the latter stage of the above coagulation precipitation treatment is employed. The amount of the inorganic coagulant used in such treatment is 2000 to 5000 mg / l, and fluorine is adsorbed on Al or Fe hydroxide to improve the fluorine removal rate. By this method, the concentration of fluorine in the treated water can be reduced to 2 to 8 mg / l.
[0004]
As another method, it has been proposed that a hydrated oxide of Zr or Ce is supported on a resin, or a fluorine adsorbent granulated with a polymer substance is used to improve the fluorine removal rate (Patent Document 1). (Japanese Patent Publication No. 6-79665) and Patent Document 2 (Japanese Patent Publication No. 61-47134). According to these methods, it is said that the treated water fluorine can be reduced to 0 to 1 mg / l.
[0005]
Here, the adsorbent is a hydrated oxide MO _n · XH ₂ O (≒ M (OH) _m ) generated by adding an alkali to a rare earth element or a salt of Ti or Zr or heating and hydrolyzing the salt. Utilizing such a property that a substance as shown exchanges anions with anions such as PO ₄ ³⁻ , F ⁻ , and SO ₄ ²⁻ on the acidic side and exchanges cations on the alkali side (Patent Document 3 (Patent Document 3)). Japanese Patent Publication No. 2-17220) and Patent Document 4 (JP-A-60-172353). M is a metal, and X, m, and n are arbitrary numbers.
[0006]
In addition, phosphorus is often contained in wastewater from the electronics industry, and phosphorus is also contained in wastewater from households. Phosphorus must be removed from the viewpoint of preventing eutrophication in closed water areas, and is subject to additional regulations in many areas. In order to remove phosphorus, similarly to the case of fluorine, a calcium salt is added and coagulated and precipitated as calcium phosphate, and an aluminum or iron-based inorganic coagulant is used to coagulate as aluminum phosphate or iron phosphate. Settling has been performed. Further, the above adsorbent can treat not only fluorine ions (F ⁻ ) but also phosphoric acid (PO ₄ ³⁻ ). Therefore, these adsorbents can be used for phosphorus removal.
[0007]
[Patent Document 1]
Japanese Patent Publication No. 6-79665 [Patent Document 2]
Japanese Patent Publication No. 61-47134 [Patent Document 3]
Japanese Patent Publication No. 2-17220 [Patent Document 4]
JP-A-60-172353
[Problems to be solved by the invention]
In the coagulation sedimentation method, several thousand mg / l of an Al or Fe-based inorganic coagulant is added to reduce fluorine or phosphorus. Such flocculated sludge incorporates water molecules into its floc, so that the sludge dewatering property is poor, and the amount of added flocculant increases the amount of generated sludge. Therefore, there is a problem that the sludge disposal cost increases. In addition, the process of generating such a large amount of waste is a technology that goes against the social demand for reducing the amount of waste.
[0009]
Further, by adding the polymer flocculant, the flocculation of the sludge becomes stronger, and the water content of the sludge can be reduced. However, there is a strong demand to further reduce the amount of sludge.
[0010]
On the other hand, the fluorine adsorbent does not increase sludge, but has a low adsorption speed and a large amount of adsorbent used. For this reason, there is a problem that the processing cost is very high. There is also a problem that the adsorbent is degraded by the oxidizing agent such as hydrogen peroxide contained in the wastewater of the electronics industry and the hydrofluoric acid of the raw water, and the base material collapses and flows out.
[0011]
The present invention has been made in view of the above problems, and has as its object to provide a processing apparatus capable of efficiently removing fluorine or phosphorus from fluorine or phosphorus-containing water.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention relates to a water-soluble compound of at least one or more metals selected from rare earth metals, Ti, Zr, Hf, V, Nb and Ta in water containing fluorine or phosphorus, and a polymer flocculant. And removing fluorine or phosphorus by adding
The polymer coagulant has a sulfone group.
[0013]
The polymer flocculant of the present invention has the following chemical formula:

And 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof as shown in the above.
[0014]
Further, the polymer coagulant of the present invention is a copolymer of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof, or acrylamide and 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof. It may be a copolymer of acrylic acid or a salt thereof.
[0015]
As described above, in the present invention, a water-soluble compound of a rare earth metal, Ti, Zr, Hf, V, Nb, and Ta is added as a fluorine or phosphorus insolubilizing agent. These metals can react with fluorine and phosphorus in an amount equivalent to the equivalent of the reaction formula to insolubilize fluorine and phosphorus. Therefore, the amount of addition is small and the amount of generated sludge is also small. Furthermore, the reaction product becomes a hydrate, and there is little possibility of taking in water, and the dewatering property of the generated sludge is improved. Therefore, the amount of generated sludge can be reduced, and the sludge disposal cost can be reduced.
[0016]
However, at a pH of 3 to 7 where a water-soluble metal compound such as a rare earth is suitable for insolubilizing fluorine and phosphorus, the floc tends to be fine, and solid-liquid separation cannot be sufficiently performed due to precipitation separation. There is. Therefore, it is conceivable to add a polymer flocculant to agglomerate the fine flocs. However, the anionic polymer flocculant which is a copolymer of acrylic acid or a salt thereof and acrylamide, which is a polymer flocculant widely used because of its low cost, has a sufficient flocculation at pH 3 to 5.5. Can not be obtained. Nonionic polymer flocculants and cationic flocculants have a flocculating effect in the pH range of 3 to 7, but the former has a weak flocculating force and thus cannot provide a sufficient flocculating effect, and the latter has a relatively high molecular weight. However, there is a problem that the solid-liquid separation cannot be sufficiently performed because the floc is hard to be coarsened.
[0017]
On the other hand, the polymer flocculant used in the present invention is an anionic polymer flocculant having a sulfone group. This polymer flocculant has a sufficient cohesive force in the above pH range, and a fine floc formed by a water-soluble compound of rare earth metal, Ti, Zr, Hf, V, Nb or Ta insolubilizing fluorine or phosphorus. Is coarsened. Therefore, the aggregated floc can be easily separated into solid and liquid in a sedimentation tank or the like, and it is possible to prevent the fine floc from leaking into the treated water and increasing the concentration of fluorine or phosphorus in the treated water. As a result, for example, in the case of fluorine, the concentration can be reliably reduced to several mg / L or less, so that fluorine or phosphorus can be efficiently removed.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention (hereinafter, referred to as embodiments) will be described with reference to the drawings. Note that the present embodiment is a preferred example for implementing the present invention, and the present invention is not limited to the present embodiment. Further, in the present embodiment, fluorine or a fluorine-containing waste water the phosphorus-containing solution, ZrO salt (preferably a ZrOCl _2.) As insolubilizing agent for fluorine or phosphorus water-soluble compounds of the 2-acrylamido as a polymer coagulant The one into which -2-methylpropanesulfonic acid or a salt thereof (AMPS) is introduced is used.
[0019]
"Embodiment 1"
FIG. 1 is a diagram showing Embodiment 1 of a removal treatment method using a fluorine or phosphorus removing agent according to the present invention. Raw water containing fluorine such as hydrofluoric acid is introduced into the zirconyl reaction tank 10. An aqueous solution containing a water-soluble compound of ZrO (eg, ZrOCl ₂ ) is supplied to the zirconyl reaction tank 10 and a pH adjuster such as sodium hydroxide (acid for lowering the pH of raw water, acid for raising) Is supplied). The pH in the zirconyl reaction vessel 10 is adjusted to 3 to 7, preferably 4 to 6, with sodium hydroxide or the like. Thereby, in the zirconyl reaction tank 10, the fluorine reacts with ZrO ²⁻ to become ZrOF ₂ and is insolubilized.
[0020]
That is,
Embedded image
ZrOCl ₂ + 2F ⁻ → ZrOF ₂ + 2Cl ⁻
By this reaction, fluorine is insolubilized.
[0021]
In the zirconyl reaction tank 10 of the present embodiment, in addition to ZrO used in the present embodiment, zirconium Zr, titanium Ti, hafnium Hf, vanadium V, niobium Nb, and tantalum Ta are used as compounds of water-soluble metals. Substances, sulfates, nitrates, chloride oxides, sulfate oxides and the like can be used. Examples of the rare earth metal compounds include scandium Sc, yttrium Y and the lanthanide lanthanum La, cerium Ce, praseodymium Pr, neodymium Nd, promethium Pm, samarium Sm, europium Eu, gadolinium Gd, terbium Tb, dysprosium Dy, and holmium Ho. Erbium Er, thulium Tm, ytterbium Yb, and lutetium Lu chloride, sulfate, and nitrate can also be used. In addition, the inside of the zirconyl reaction tank 10 needs to be adjusted to a pH range of 3 to 7 which is optimal for the reaction thereof, but a pH range of 4 to 6 is particularly preferable.
[0022]
Next, the treated water in the zirconyl reaction tank 10 is supplied to the coagulation tank 12. The coagulation tank 12 is supplied with a polymer coagulant, and the insolubilized fluorine generated in the zirconyl reaction tank 10 is coagulated and coarsened.
[0023]
Here, a polymer flocculant having a sulfone group is employed. In the present embodiment, a polymer flocculant having a sulfone group is represented by the following chemical formula:

And the like, into which 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof (AMPS) has been introduced. The polymer flocculant is a copolymer of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof, or acrylamide and 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof and acrylic acid or a salt thereof. May be used. The molecular weight of the polymer coagulant is not particularly limited, but is more preferably in the range of 5,000,000 to 20,000,000. These polymer flocculants can be used alone or as a mixture. Further, the addition amount of these polymer flocculants may be arbitrarily set, but is preferably in the range of 1 to 100 mg / liter (L) in view of the balance between the flocculation and sedimentation effects and economy.
[0024]
In addition, before adding the polymer flocculant in the present embodiment, an inorganic flocculant can be added. Examples of the inorganic flocculant include polyvalent metal salts such as ferrous sulfate, ferric sulfate, polyiron sulfate, ferrous chloride, ferric chloride, polyaluminum chloride, aluminum sulfate (sulfate band), and aluminum chloride. Etc. may be used. More preferred flocculants are ferric chloride and polysulfate. These inorganic coagulants may be used alone or as a mixture.
[0025]
Further, the coagulation treatment water from the coagulation tank 12 is introduced into the sedimentation tank 14, where the solids are settled and separated. That is, the above-mentioned aggregates formed by introducing the fluorine-insoluble ZrOF ₂ polymer coagulant (AMPS) are precipitated and separated, and treated water having a low fluorine concentration is obtained as a supernatant.
[0026]
In addition, as a solid-liquid separation means of the aggregate, various devices can be used without being limited to the precipitation tank 14. Flotation, centrifugation, vibrating sieve, membrane separation, etc. may be used. In particular, the membrane separation device is excellent in its ability to separate solids and is suitable.
[0027]
In addition, the above-mentioned water-soluble compounds of metals, polymer coagulants, inorganic coagulants, pH adjusters, types and amounts of each agent such as calcium salt, stirring conditions in each tank, and the like are designed to be optimal. Good. For example, a jar test in which the type and amount of each agent and the stirring conditions in each tank are changed is performed, and the jar test is determined based on the floc diameter of the generated aggregates, solid-liquid separation properties, and the amount of generated sludge.
[0028]
"Embodiment 2"
FIG. 2 is a view showing Embodiment 2 of a removal treatment method using a fluorine or phosphorus removing agent according to the present invention. The second embodiment has a configuration suitable for drainage containing a high concentration of fluorine. That is, from an economic viewpoint, the treatment of adding a rare earth metal or the like according to the present embodiment is preferably applied to raw water having a reduced fluorine concentration (preferably 20 mg / L or less). On the other hand, in the case of industrial industrial wastewater, the fluorine concentration is often about 100 to 2000 mg / L. In such a case, it is preferable to remove the remaining fluorine by the treatment described in Embodiment 1 of the present embodiment after performing the conventional fluorine treatment with a calcium salt.
[0029]
Raw water containing a high concentration of fluorine is first introduced into the calcium reaction tank 20. A calcium salt such as slaked lime or calcium chloride is supplied to the calcium reaction tank 20. If necessary, a pH adjuster such as sodium hydroxide is added as necessary, and the pH is adjusted to a pH (approximately 4 to 11) suitable for the precipitation of calcium fluoride. The amount of calcium salt added to the treated water in the calcium reaction tank 20 may be any amount as long as the fluorine concentration can be reduced, and may be an amount less than the conventional amount of fluorine treatment.
[0030]
After the calcium salt is added to the calcium reactor 20 to generate calcium fluoride, the calcium fluoride is introduced into the zirconyl reactor 10 as it is, and an aqueous solution of ZrOCl ₂ is added to insolubilize the remaining fluorine. The zirconyl reaction tank 10, coagulation tank 12, and sedimentation tank 14 are used for the treatment as described above. By such a treatment, fluorine can be treated to a low concentration, and the addition amount of a calcium salt or an inorganic / organic coagulant can be relatively reduced. Further, the addition amount of the ZrO salt may be relatively small. In this treatment, an inorganic coagulant may be added as necessary.
[0031]
"Other"
The above description has been directed only to the treatment of fluorine-containing water. However, a water-soluble compound of a metal composed of at least one of rare earth metals, Ti, Zr, Hf, V, Nb, and Ta also causes the same insolubilization reaction with phosphorus as fluorine. Therefore, the above-described treatment can be directly applied to the phosphorus-containing water. In addition, since phosphorus can be removed as calcium phosphate, the treatment of adding a calcium salt can be applied to phosphorus-containing water as it is, and for example, phosphorus is insolubilized by the following reaction. Note that the form of phosphorus changes depending on the pH and the like.
Embedded image
ZrOCl ₂ + 2H ₂ PO ₄ ⁻ → ZrO (H ₂ PO ₄ ) ₂ + 2Cl ⁻
ZrOCl ₂ + HPO ₄ ²⁻ → ZrOHPO ₄ + 2Cl ⁻
[0032]
Further, the present invention can be suitably applied to water containing both fluorine and phosphorus. In this case, a rare earth metal salt or the like may be added in an amount equal to or more than the total of each equivalent to fluorine and phosphorus.
[0033]
【Example】
"Experiment 1"
Next, using the polymer flocculant of the present invention, a treatment experiment of fluorine-containing water corresponding to the first embodiment was performed. A solution prepared by dissolving sodium fluoride in pure water so as to have a fluorine concentration of 20 mg-F / L was prepared and used as raw water. An aqueous solution of zirconium chloride having a zirconium content of 10% as a fluorine insolubilizing agent was added to the raw water so as to have a concentration of 50 mg-Zr / L. Further, NaOH was added as a pH adjuster to adjust the pH to 5. By stirring for 30 minutes, the fluorine and the zirconium salt were sufficiently reacted to generate an insolubilized product.
[0034]
Thereafter, a polymer coagulant was added to the raw water to a concentration of 1 mg / L, and the mixture was stirred for 10 minutes, and the generated insolubilized product was sufficiently coagulated with the polymer coagulant. The mixture was allowed to stand for 30 minutes, and after the aggregates were sufficiently precipitated, the supernatant was collected as treated water, and the fluorine concentration of the treated water was measured. Three types shown in Table 1 were used as polymer flocculants. All are anionic polymer flocculants (manufactured by Organo Corporation), and among them, only OA-34 (trade name) into which 2-acrylamido-2-methylpropanesulfonic acid is introduced. Table 1 shows the results of the fluorine concentration in the treated water.
[Table 1]

[0035]
As described above, the treated water using the conventional anionic polymer flocculant shown in Comparative Examples 1 and 2 is 3.5 mg-F / L or more, whereas the OA-34 ( It can be seen that the fluorine concentration in the treated water was reduced to 0.7 mg-F / L, which was 0.7 times less than that of the comparative example. When the treated water was visually observed, fine flocs were observed in Comparative Examples 1 and 2, and the treated water was cloudy, but in the embodiment, the supernatant of the treated water was transparent. This is considered to be because in the embodiment, the floc easily settles in the sedimentation tank, and the fluorine-containing substance hardly leaks from the sedimentation tank, so that the fluorine in the treated water can be reduced more than before.
[0036]
"Experiment 2"
Further, using the polymer flocculant of the present invention, a fluorine-containing water treatment experiment corresponding to the second embodiment was performed. Sodium fluoride was dissolved in pure water to prepare a fluorine concentration of 200 mg-F / L, which was used as raw water. After adding slaked lime as a calcium salt at 1000 mg / L to generate calcium fluoride in the raw water, HCl was added as a pH adjuster to adjust the pH to 10. By stirring for 30 minutes, fluorine and slaked lime were sufficiently reacted to generate calcium fluoride.
[0037]
Then, a cerium chloride aqueous solution having a cerium content of 10% was added to the raw water so as to have a concentration of 50 mg-Ce / L as a fluorine insolubilizing agent. Further, NaOH was added as a pH adjuster to adjust the pH to 5. By further stirring for 30 minutes, the fluorine and the cerium salt were sufficiently reacted to generate an insolubilized product. Thereafter, a polymer coagulant was added to the raw water to a concentration of 1 mg / L, and the mixture was stirred for 10 minutes, and the generated insolubilized product was sufficiently coagulated with the polymer coagulant. The mixture was allowed to stand for 30 minutes, and after the aggregates were sufficiently precipitated, the supernatant was collected as treated water, and the fluorine concentration of the treated water was measured. As the polymer flocculant, the same three types as in Table 1 were used. All are anionic polymer flocculants (manufactured by Organo Corporation), and among them, only OA-34 (trade name) into which 2-acrylamido-2-methylpropanesulfonic acid is introduced. Table 2 shows the results of the fluorine concentration in the treated water.
[Table 2]

[0038]
As described above, the treated water using the conventional anionic polymer flocculant shown in Comparative Examples 1 and 2 is 5 mg-F / L or more, whereas the OA-34 (trade name) of the embodiment is used. ) Shows that the fluorine concentration in the treated water could be reduced to 0.8 mg-F / L, which is 1/5 or less of the comparative example. When the treated water was visually observed, in Comparative Examples 1 and 2, a large amount of fine flocs were observed and the mixture was strongly clouded as compared with the result of the corresponding experiment 1, but in the embodiment, the supernatant of the treated water was transparent. This is because, similarly to the result of Experiment 1, in the embodiment, the floc easily settles in the sedimentation tank, and the fluorine-containing substance hardly leaks from the sedimentation tank. Can be
[0039]
As described above, an insoluble material of fluorine or phosphorus such as a suitable rare earth metal salt can be effectively agglomerated using an anionic polymer flocculant in which AMPS is introduced.
[0040]
【The invention's effect】
As described above, in the present invention, a polymer flocculant having a sulfone group is used as the polymer flocculant. This polymer coagulant has sufficient cohesion at a pH of 3 to 7, which is suitable for a rare earth metal, a water-soluble compound of Ti, Zr, Hf, V, Nb, and Ta to insolubilize fluorine and phosphorus. , Ti, Zr, Hf, V, Nb, and Ta water-soluble compounds insolubilize fluorine and phosphorus to aggregate and coarsen fine flocs. For this reason, the flocculated floc can be easily separated into solid and liquid in a sedimentation tank or the like, and it is possible to prevent the fine floc from leaking into the treated water and increasing the concentration of fluorine or phosphorus in the treated water. As a result, for example, in the case of fluorine, the concentration can be reliably reduced to several mg / L or less, and the fluorine or phosphorus can be efficiently removed.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a first embodiment.
FIG. 2 is a diagram showing a configuration of a second embodiment.
[Explanation of symbols]
10 reaction tanks, 12 coagulation tanks, 14 sedimentation tanks, 20 calcium reaction tanks.

Claims (3)

Removal of fluorine or phosphorus by adding a water-soluble compound of at least one of rare earth metals, Ti, Zr, Hf, V, Nb and Ta to a water containing fluorine or phosphorus and a polymer coagulant In the method,
The polymer flocculant has a sulfone group,
A method for removing fluorine or phosphorus. The polymer flocculant has the following chemical formula

2-acrylamido-2-methylpropanesulfonic acid or a salt thereof shown therein is introduced,
The method for removing fluorine or phosphorus according to claim 1, wherein: The polymer flocculant is a copolymer of acrylamide and 2-acrylamide-2-methylpropanesulfonic acid or a salt thereof,
Or a copolymer of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof and acrylic acid or a salt thereof,
The method for removing fluorine or phosphorus according to claim 1 or 2, wherein:

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