JP2003117564A - Method for treating fluorine-containing waste water - Google Patents
Method for treating fluorine-containing waste waterInfo
- Publication number
- JP2003117564A JP2003117564A JP2001314928A JP2001314928A JP2003117564A JP 2003117564 A JP2003117564 A JP 2003117564A JP 2001314928 A JP2001314928 A JP 2001314928A JP 2001314928 A JP2001314928 A JP 2001314928A JP 2003117564 A JP2003117564 A JP 2003117564A
- Authority
- JP
- Japan
- Prior art keywords
- fluorine
- slurry
- hydroxide
- dehydrated
- waste water
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Treating Waste Gases (AREA)
- Removal Of Specific Substances (AREA)
- Water Treatment By Sorption (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、脱硫装置から排出
される排水中に含まれるフッ素を、廃棄物である脱水ケ
ーキを極力発生させずに処理することができるフッ素含
有排水の処理方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating fluorine-containing wastewater, which is capable of treating fluorine contained in wastewater discharged from a desulfurization unit without generating dehydrated cake which is waste. Is.
【０００２】[0002]
【従来の技術】例えば、石炭焚き発電所に設置されてい
る脱硫装置から排出される排水中にはフッ素が含まれて
いるため、これを基準値以下となるように除去処理する
必要がある。従来の一般的なフッ素含有排水の処理方法
としては、例えば図２に示されるように、排水に薬品を
添加して沈殿させる凝集沈殿法が知られている。この方
法は、先ず処理すべき排水を塩酸（ＨＣｌ）でｐＨ調整
した後、反応槽で消石灰（Ｃａ（ＯＨ）2）と反応させ
てフッ化カルシウム（ＣａＦ2）を生成し、次いで高分
子凝集剤を加えて凝集・沈殿処理する１段目の凝集沈殿
処理と、更に排水中に残留したフッ素をポリ塩化アルミ
ニウム（ＰＡＣ）と共沈させ、次いで高分子凝集剤を加
えて凝集・沈殿処理する２段目の凝集沈殿処理とからな
り、フッ素を脱水ケーキとして系外へ取り出すものであ
る。しかしながら、この方法の場合は脱水ケーキの発生
量が多く、また使用する薬品量も多くなるという問題点
があった。2. Description of the Related Art For example, since fluorine is contained in the wastewater discharged from a desulfurization unit installed in a coal-fired power plant, it is necessary to remove fluorine so that it falls below a standard value. As a conventional general method for treating fluorine-containing wastewater, for example, as shown in FIG. 2, a coagulation sedimentation method is known in which a chemical is added to wastewater to cause precipitation. In this method, the pH of the wastewater to be treated is first adjusted with hydrochloric acid (HCl), then reacted with slaked lime (Ca (OH) 2 ) in a reaction tank to produce calcium fluoride (CaF 2 ), and then polymer aggregation is carried out. The first step of coagulation / precipitation in which an agent is added and coagulation / precipitation is performed, and fluorine remaining in the wastewater is further coprecipitated with polyaluminum chloride (PAC), and then a polymer coagulant is added to perform coagulation / precipitation processing. The second step is coagulation and sedimentation, and fluorine is taken out of the system as a dehydrated cake. However, this method has a problem that a large amount of dehydrated cake is generated and a large amount of chemicals is used.
【０００３】このような２段式の凝集沈殿法の問題点を
解決する方法として、最近では図３に示されるように、
反応槽に水酸化ナトリウム（ＮａＯＨ）を添加してｐＨ
を９以上に調整し、硫黄酸化物の吸着剤である水酸化マ
グネシウムにフッ素イオンを吸着させて凝集・沈殿処理
する１段式の凝集沈殿法が提案されている（例えば、特
開２０００−１７６２４１号公報参照）。しかしなが
ら、この方法の場合はｐＨを高めるのに多量の水酸化ナ
トリウムが必要になるという問題点があるうえに、沈殿
槽で得られたスラリーを再度脱硫装置への返送を繰り返
すため、フッ素濃度が濃縮しきった際は返送が不可能と
なって、全量脱水ケーキとして系外へ取り出し廃棄する
必要があり、この場合の脱水ケーキの廃棄量は膨大で、
また廃棄作業も膨大なものになるという問題点があっ
た。As a method for solving the problems of the two-step type coagulation-sedimentation method, recently, as shown in FIG.
Add sodium hydroxide (NaOH) to the reaction tank to adjust the pH.
Is adjusted to 9 or more, and a one-step coagulation-sedimentation method is proposed in which magnesium hydroxide, which is an adsorbent for sulfur oxides, adsorbs fluorine ions to perform coagulation / precipitation treatment (for example, JP-A-2000-176241). (See the official gazette). However, in the case of this method, there is a problem that a large amount of sodium hydroxide is required to raise the pH, and since the slurry obtained in the settling tank is repeatedly returned to the desulfurization device, the fluorine concentration becomes high. When it is completely concentrated, it cannot be returned, and it is necessary to take it out of the system as a whole dehydrated cake and discard it. In this case, the amount of dehydrated cake discarded is enormous.
There was also the problem that the amount of disposal work would be enormous.
【０００４】[0004]
【発明が解決しようとする課題】本発明は上記のような
従来の問題点を解決して、脱硫装置から排出される排水
中に含まれるフッ素を、廃棄物である脱水ケーキを極力
発生させずに処理することができ、しかも脱水ケーキの
ろ過速度も十分に確保することができるとともに、反応
槽に添加する水酸化ナトリウムの量も少なくてランニン
グコストを安価なものとすることができるフッ素含有排
水の処理方法を提供することを目的として完成されたも
のである。DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems and prevents fluorine contained in wastewater discharged from a desulfurization unit from generating dehydrated cake as waste as much as possible. Fluorine-containing wastewater that can be treated at a low cost and can also ensure a sufficient filtration rate for the dehydrated cake, and also reduce the running cost due to the small amount of sodium hydroxide added to the reaction tank. It has been completed for the purpose of providing a treatment method of.
【０００５】[0005]
【課題を解決するための手段】上記の課題を解決するた
めになされた本発明のフッ素含有排水の処理方法は、水
酸化マグネシウムを吸着剤として用いた脱硫装置から排
出される排水を、ｐＨ調整槽でｐＨ調整を行った後、反
応槽で排水中に含まれるフッ素を沈殿化合物に吸着させ
て凝集沈殿により除去処理するようにしたフッ素含有排
水の処理方法であって、ｐＨ調整槽の後段において水酸
化カルシウムを添加することによりフッ化カルシウムを
生成後、脱水スラリーとしてフッ素の一部を系外へ取り
出す一方、反応槽に水酸化ナトリウムを加えることによ
りフッ素を吸着した塩基性硫酸マグネシウムおよび水酸
化マグネシウムを生成させた後、これらを含んだスラリ
ーをｐＨ調整槽に返送してスラリー中の水酸化マグネシ
ウムを酸と反応させて溶解し処理水として排出するとと
もに、塩基性硫酸マグネシウムのフッ素吸着度を高め、
この返送サイクルにより最終的にはフッ素を十分に吸着
した塩基性硫酸マグネシウムを含んだスラリーを脱水
後、脱水スラリーとしてフッ素の残部を系外へ取り出す
ことを特徴とするものである。The method for treating fluorine-containing wastewater of the present invention made to solve the above-mentioned problems is to adjust pH of wastewater discharged from a desulfurization apparatus using magnesium hydroxide as an adsorbent. A method for treating fluorine-containing wastewater, wherein after performing pH adjustment in a tank, fluorine contained in wastewater in a reaction tank is adsorbed to a precipitation compound and removed by coagulation sedimentation. After generating calcium fluoride by adding calcium hydroxide, part of the fluorine is taken out of the system as a dehydrated slurry, while sodium hydroxide is added to the reaction tank to add basic magnesium sulfate and hydroxide After magnesium is generated, the slurry containing them is returned to the pH adjusting tank to react the magnesium hydroxide in the slurry with the acid. With discharged as molten treated water Te increases the fluorine adsorption of the basic magnesium sulfate,
This return cycle is characterized by finally dehydrating the slurry containing basic magnesium sulfate sufficiently adsorbing fluorine, and taking out the rest of fluorine as a dehydrated slurry out of the system.
【０００６】前記水酸化カルシウムの添加は、ｐＨ調整
後からスラリー脱水までの間に行うことが好ましく、こ
れを請求項２に係る発明とする。また同一の課題を解決
するためになされた請求項３に係る発明は、ｐＨ調整槽
のｐＨが中性域となるように調整するものであり、更に
同一の課題を解決するためになされた請求項４に係る発
明は、反応槽のｐＨが８以上となるように調整するもの
である。[0006] The addition of the calcium hydroxide is preferably performed after the pH adjustment and before the dehydration of the slurry. This is the invention according to claim 2. Further, the invention according to claim 3 made to solve the same problem is to adjust the pH of the pH adjusting tank to be in a neutral range, and further made to solve the same problem. The invention according to item 4 is to adjust the pH of the reaction tank to 8 or more.
【０００７】[0007]
【発明の実施の形態】以下に、図面を参照しつつ本発明
の好ましい実施の形態を示す。図１は、本発明に係るフ
ッ素含有排水の処理方法の概略フロー図を示すものであ
る。本発明の対象となる被処理水（原水）は、例えば石
炭焚き発電所に設置されている水酸化マグネシウムを吸
着剤として用いた脱硫装置から排出される排水であり、
排水中にフッ素を含有するものである。また、除去処理
方法としては、一般的な二段式凝集沈殿法を基本とする
ものである。BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic flow chart of a method for treating fluorine-containing wastewater according to the present invention. The water to be treated (raw water) to be the subject of the present invention is, for example, waste water discharged from a desulfurization device using magnesium hydroxide as an adsorbent installed in a coal-fired power plant,
The wastewater contains fluorine. In addition, the removal treatment method is based on the general two-stage coagulation sedimentation method.
【０００８】先ず、脱硫装置から排出された排水は、ｐ
Ｈ調整槽に導かれて、ここで凝集沈殿処理に適したｐＨ
に調製される。次に、ｐＨ調整された排水は反応槽に導
かれ、ここで排水中に含まれるフッ素が沈殿化合物に吸
着されて凝集沈殿により除去処理されることとなる。First, the wastewater discharged from the desulfurizer is p
Guided to the H adjustment tank, where the pH suitable for coagulation sedimentation treatment
Is prepared. Next, the pH-adjusted wastewater is introduced into the reaction tank, where the fluorine contained in the wastewater is adsorbed by the precipitation compound and is removed by coagulation precipitation.
【０００９】そして本発明では、この反応槽に水酸化ナ
トリウム（ＮａＯＨ）を加えることによりフッ素を吸着
した塩基性硫酸マグネシウムおよび水酸化マグネシウム
を生成させる点を第１の特徴とする。従来、反応槽に消
石灰（Ｃａ（ＯＨ）2）を加えることにより、原水中の
フッ素をＣａにより固定し、フッ化カルシウムを生成さ
せて汚泥として除去処理していた。この場合、反応槽で
の化学反応は次の化１に示されるとおりである。The first feature of the present invention is that sodium hydroxide (NaOH) is added to this reaction vessel to produce basic magnesium sulfate and magnesium hydroxide having adsorbed fluorine. Conventionally, by adding slaked lime (Ca (OH) 2 ) to a reaction tank, fluorine in the raw water is fixed by Ca, calcium fluoride is generated, and it is removed as sludge. In this case, the chemical reaction in the reaction tank is as shown in the following chemical formula 1.
【００１０】[0010]
【化１】 [Chemical 1]
【００１１】即ち、消石灰によるフッ素の除去は、フッ
素をフッ化カルシウム、フッ化アルミニウムとして沈殿
させ、汚泥として抜き出していた。これらの割合は、本
発明者の汚泥成分の分析結果によればＭｇ（ＯＨ）2が
約４８％、フッ化カルシウムおよびフッ化アルミニウム
が約３％である。そして、汚泥成分中の約２２％は石膏
（ＣａＳＯ4）、約２７％はＡｌ、Ｆｅ等の注入薬品起
因の水酸化物である。つまり、本発明者は消石灰を用い
た場合には、汚泥成分として原水中の硫酸イオンの影響
を受けて多量の石膏が発生しており、これが汚泥の発生
量を増大させていることを解明した。That is, in the removal of fluorine by slaked lime, fluorine was precipitated as calcium fluoride and aluminum fluoride and extracted as sludge. According to the analysis result of the sludge component of the present inventor, these ratios are about 48% for Mg (OH) 2 and about 3% for calcium fluoride and aluminum fluoride. About 22% of the sludge component is gypsum (CaSO 4 ), and about 27% is hydroxide caused by injected chemicals such as Al and Fe. That is, the present inventor has clarified that when slaked lime is used, a large amount of gypsum is generated under the influence of sulfate ions in raw water as a sludge component, which increases the amount of sludge generated. .
【００１２】従って、本発明では従来の消石灰にかえ反
応槽に水酸化ナトリウム（ＮａＯＨ）を加えることによ
り、化２に示されるように、塩基性硫酸マグネシウムお
よび水酸化マグネシウムを生成させることにした。これ
により、石膏（ＣａＳＯ4）の発生をなくし汚泥発生量
の低減化をねらうものである。Therefore, in the present invention, by adding sodium hydroxide (NaOH) to the conventional slaked lime replacing reaction tank, basic magnesium sulfate and magnesium hydroxide are produced as shown in Chemical formula 2. This aims to eliminate the generation of gypsum (CaSO 4 ) and reduce the amount of sludge generated.
【００１３】[0013]
【化２】 [Chemical 2]
【００１４】一方、この方法によるときは、石膏にかえ
固形分として塩基性硫酸マグネシウムおよび水酸化マグ
ネシウムが生成されるが、これらは以下のとおり処理す
ることで汚泥増加の要因にはならない。即ち、本発明で
は生成した前記スラリーをｐＨ調整槽に返送してスラリ
ー中の水酸化マグネシウムを酸と反応させて溶解し処理
水として排出するとともに、塩基性硫酸マグネシウムの
フッ素吸着度を高め、この返送サイクルを繰り返すこと
により最終的にはフッ素を十分に吸着した塩基性硫酸マ
グネシウムを含んだスラリーを脱水後、脱水スラリーと
して系外へ取り出すようにした点を第２の特徴とする。On the other hand, according to this method, basic magnesium sulfate and magnesium hydroxide are produced as solids instead of gypsum, but these are not a factor for increasing sludge by treating as follows. That is, in the present invention, the generated slurry is returned to the pH adjusting tank, magnesium hydroxide in the slurry is reacted with an acid to be dissolved and discharged as treated water, and the degree of fluorine adsorption of basic magnesium sulfate is increased. The second feature is that by repeating the returning cycle, the slurry containing the basic magnesium sulfate in which fluorine is sufficiently adsorbed is finally dehydrated and then taken out of the system as a dehydrated slurry.
【００１５】発生した水酸化マグネシウムは難溶解性の
物質であるが、化３に示されるように、酸（例えば塩酸
や硫酸）と反応させることによって溶解性の高い化合物
（ＭｇＣｌ2やＭｇＳＯ4）に変化させることが可能であ
り、本発明ではこの反応を利用して水酸化マグネシウム
を溶解し、処理水として系外へ排出するのである。これ
により、実質的に汚泥発生量の低減が図れることとな
る。また、塩基性硫酸マグネシウムは吸着力に優れた物
質であり、これをｐＨ調整槽に返送することにより、フ
ッ素の吸着剤として再利用し更にフッ素の吸着除去を促
進するのである。そして、この返送サイクルを繰り返す
ことにより最終的にはフッ素を十分に吸着した塩基性硫
酸マグネシウムを含んだスラリーとし、これを脱水処理
した後、脱水スラリーとして系外へ取り出すことでフッ
素の除去を行うのである。The generated magnesium hydroxide is a hardly soluble substance, but as shown in Chemical formula 3, a compound having a high solubility (MgCl 2 or MgSO 4 ) can be obtained by reacting with an acid (for example, hydrochloric acid or sulfuric acid). In the present invention, magnesium hydroxide is dissolved by utilizing this reaction and discharged out of the system as treated water. As a result, the amount of sludge generated can be substantially reduced. In addition, basic magnesium sulfate is a substance having an excellent adsorptive power, and by returning this to the pH adjusting tank, it is reused as a fluorine adsorbent and further promotes the adsorption and removal of fluorine. Then, by repeating this returning cycle, finally a slurry containing basic magnesium sulfate in which fluorine is sufficiently adsorbed is dehydrated, and after this is dehydrated, fluorine is removed by taking it out of the system as dehydrated slurry. Of.
【００１６】[0016]
【化３】 [Chemical 3]
【００１７】また、本発明者の研究によれば、前記のよ
うに水酸化ナトリウム（ＮａＯＨ）を加えることによ
り、排水中に含まれる全部のフッ素を吸着・除去処理す
ることは、汚泥量の削減には非常に大きな効果を奏する
ものの、汚泥が微粒になり、脱水性が従来に比べ低下
し、汚泥脱水機の余力がない場合は安定操業が難しくな
る場合がある。このため、本発明ではｐＨ調整槽の後段
において水酸化カルシウムを添加することによりフッ化
カルシウムを生成後、脱水スラリーとしてフッ素の一部
を系外へ取り出すようにした点を第３の特徴とする。According to the research conducted by the present inventor, it is possible to reduce the amount of sludge by adsorbing and removing all the fluorine contained in the wastewater by adding sodium hydroxide (NaOH) as described above. However, the sludge becomes fine particles, the dewatering property is reduced as compared with the conventional one, and stable operation may be difficult when the sludge dewatering machine has no reserve capacity. Therefore, the third feature of the present invention is that after the calcium hydroxide is generated by adding calcium hydroxide in the latter stage of the pH adjusting tank, a part of the fluorine is taken out of the system as a dehydrated slurry. .
【００１８】即ち、水酸化ナトリウムにより処理して脱
水ケーキを生成する場合は、汚泥の粒子が非常に細かく
なるため、ろ布の目詰まりが生じてろ過速度が低下する
要因となるとともに、生成した脱水ケーキの剥離性が悪
くなりろ布の交換頻度が高くなるという問題点があっ
た。そこで本発明では、水酸化カルシウムを添加するこ
とによりフッ素の一部を系外へ取り出すようにすること
で、汚泥量の削減を図るとともに一定値以上のろ過速度
も確保して実操業の薬品コストを含めたトータルコスト
を大幅に低減化するのである。この場合、水酸化カルシ
ウムを添加することでろ布の目詰まりを防止できるの
は、水酸化カルシウムはスラリー状で添加するため、フ
ッ素と反応した残分粒子が水酸化ナトリウム（ＮａＯ
Ｈ）と反応して、析出した水酸化マグネシウム（Mg(OH)
2）に比べて大きいため、ろ布表面においてある程度の
空隙を保持した状態で付着することとなり、ろ液の流通
性が確保されるとともに剥離性も向上するのである。That is, when the dehydrated cake is produced by treating with sodium hydroxide, the sludge particles become very fine, which causes clogging of the filter cloth and causes a decrease in the filtration rate. There is a problem in that the peelability of the dehydrated cake deteriorates and the frequency of filter cloth replacement increases. Therefore, in the present invention, by adding calcium hydroxide so that a part of the fluorine is taken out of the system, it is possible to reduce the amount of sludge and also secure a filtration rate of a certain value or more to reduce the chemical cost of actual operation. The total cost, including the above, will be greatly reduced. In this case, it is possible to prevent the filter cloth from being clogged by adding calcium hydroxide because calcium hydroxide is added in the form of a slurry, so that the residual particles that have reacted with fluorine are sodium hydroxide (NaO).
H) and precipitated magnesium hydroxide (Mg (OH)
Since it is larger than that of 2 ), it adheres to the surface of the filter cloth while holding some voids, which ensures the flowability of the filtrate and improves the peelability.
【００１９】この場合、前記水酸化カルシウムの添加
は、ｐＨ調整後からスラリー脱水までの間に行う。具体
的には、図１に示されるように、ｐＨ調整槽の後段にあ
る第１反応槽や第１凝集槽のいずれか、あるいはその両
方に添加することができる。また、水酸化カルシウムの
添加量としては、前記水酸化ナトリウムに対し２０〜１
００重量％の範囲が好ましい。２０重量％より少ないと
十分なろ過速度の確保が難しく、一方、１００重量％よ
り多いと十分な汚泥量の削減を図ることが難しくなるか
らである。なお、前記水酸化カルシウムに代えて塩化鉄
を用いることも可能である。In this case, the calcium hydroxide is added after the pH adjustment and before the slurry dehydration. Specifically, as shown in FIG. 1, it can be added to either or both of the first reaction tank and the first coagulation tank downstream of the pH adjusting tank. The amount of calcium hydroxide added is 20 to 1 with respect to the sodium hydroxide.
A range of 00% by weight is preferred. This is because if it is less than 20% by weight, it is difficult to secure a sufficient filtration rate, while if it is more than 100% by weight, it becomes difficult to sufficiently reduce the sludge amount. It is also possible to use iron chloride instead of the calcium hydroxide.
【００２０】また、ｐＨ調整槽のｐＨが中性域となるよ
うに調整することが好ましい。水酸化マグネシウムを主
体とするスラリーが再溶解しやすくなり、系外へ排出す
る脱水ケーキの量を削減できるからである。また、反応
槽のｐＨが８以上、望ましくは９以上となるように調整
することが好ましい。硫酸マグネシウムの塩基性硫酸マ
グネシウムへの転化率を高めるためである。Further, it is preferable to adjust the pH of the pH adjusting tank to be in the neutral range. This is because the slurry mainly composed of magnesium hydroxide is easily redissolved, and the amount of dehydrated cake discharged to the outside of the system can be reduced. Further, it is preferable to adjust the pH of the reaction tank to 8 or more, preferably 9 or more. This is to increase the conversion rate of magnesium sulfate to basic magnesium sulfate.
【００２１】更には、塩基性硫酸マグネシウムをｐＨ調
整槽へ返送することにより、吸着力に優れた塩基性硫酸
マグネシウムが原水中のフッ素を事前に吸着して除去す
るため、反応槽に添加する水酸化ナトリウムの量を大幅
に削減することができ、薬品コストの低減化が可能とな
る。Further, by returning the basic magnesium sulfate to the pH adjusting tank, the basic magnesium sulfate having an excellent adsorbing power adsorbs and removes fluorine in the raw water in advance, so that the water added to the reaction tank is removed. The amount of sodium oxide can be significantly reduced, and the chemical cost can be reduced.
【００２２】以上のように、本発明では反応槽に水酸化
ナトリウムを加えることにより塩基性硫酸マグネシウム
および水酸化マグネシウムを生成させるとともに、得ら
れたスラリーをｐＨ調整槽に返送してスラリー中の水酸
化マグネシウムを酸と反応させて溶解させるようにした
ので、従来の消石灰を加えて反応させたものに比べて、
石膏の発生が少なく汚泥発生量を著しく低減できること
となる。また塩基性硫酸マグネシウムをｐＨ調整槽に返
送するのでフッ素を高濃度の状態で除去処理ができるこ
ととなり、添加する水酸化ナトリウムの量も大幅に削減
することができることとなる。更には、水酸化カルシウ
ムを添加することによりフッ素の一部を系外へ取り出す
ようにすることで、後段の水酸化ナトリウム添加量を削
減でき、かつ汚泥量の削減を図るとともに一定値以上の
ろ過速度も確保して薬品コストを含めたトータルコスト
を大幅に低減化するとともに、安定した繰業が可能とな
る。このように本発明では、生成した塩基性硫酸マグネ
シウムおよび水酸化マグネシウムはいずれも汚泥増加の
要因とはならないため、従来法に比べて約４０〜５０％
の汚泥削減が可能となる。As described above, in the present invention, sodium hydroxide is added to the reaction tank to generate basic magnesium sulfate and magnesium hydroxide, and the resulting slurry is returned to the pH adjusting tank to remove water in the slurry. Since magnesium oxide was made to react with an acid to dissolve it, compared to the conventional one in which slaked lime was added and reacted,
The amount of gypsum generated is small and the amount of sludge generated can be significantly reduced. Further, since the basic magnesium sulfate is returned to the pH adjusting tank, fluorine can be removed in a high concentration state, and the amount of sodium hydroxide added can be greatly reduced. Furthermore, by adding calcium hydroxide so that part of the fluorine can be taken out of the system, the amount of sodium hydroxide added in the latter stage can be reduced, and the amount of sludge can be reduced and filtration above a certain level can be achieved. It is possible to secure a speed and drastically reduce the total cost including the chemicals cost, and it is possible to carry out stable operations. As described above, in the present invention, since neither the generated basic magnesium sulfate nor magnesium hydroxide is a factor for increasing sludge, it is about 40 to 50% as compared with the conventional method.
It is possible to reduce the sludge.
【００２３】[0023]
【実施例】石炭焚き発電所に設置されている水酸化マグ
ネシウムを吸着剤として用いた脱硫装置から排出される
排水を、図１に示される処理工程に従い処理を行った結
果は、表１に示すとおりであった。最終処理水中のフッ
素含有量はいずれも目標値である１０ｍｇ／Ｌを完全に
クリヤーしており、汚泥発生量も水酸化カルシウムのみ
で処理する従来に比べて４０〜５０％削減できることが
確認できた。また、ろ過速度も従来法による場合の８割
程度確保できており、汚泥発生量の削減効果と合わせ必
要ろ過面積も小さくてすむため装置を安全サイドに設計
することができるとともに、実操業のトータルコストを
大幅に低減化できることが確認できた。[Examples] Table 1 shows the results obtained by treating the wastewater discharged from the desulfurization device using magnesium hydroxide as an adsorbent installed in a coal-fired power plant according to the treatment process shown in FIG. It was as it was. The fluorine content in the final treated water was completely cleared to the target value of 10 mg / L, and it was confirmed that the sludge generation amount could be reduced by 40 to 50% compared with the conventional method in which only calcium hydroxide was treated. . In addition, the filtration speed has been secured at about 80% of that of the conventional method, and in addition to the effect of reducing the amount of sludge generated, the required filtration area can be small, so the device can be designed on the safe side and the total operation It was confirmed that the cost could be significantly reduced.
【００２４】[0024]
【表１】 [Table 1]
【００２５】[0025]
【発明の効果】以上の説明からも明らかなように、本発
明は脱硫装置から排出される排水中に含まれるフッ素
を、廃棄物である脱水ケーキを極力発生させずに処理す
ることができ、しかも脱水ケーキのろ過速度も十分に確
保することができるとともに、反応槽に添加する水酸化
ナトリウムの量も少なくてランニングコストを安価なも
のとすることができるものである。よって本発明は従来
の問題点を一掃したフッ素含有排水の処理方法として、
産業の発展に寄与するところは極めて大である。As is apparent from the above description, the present invention can treat the fluorine contained in the waste water discharged from the desulfurization device without generating the dehydrated cake as waste as much as possible. Moreover, it is possible to secure a sufficient filtration rate for the dehydrated cake and to reduce the running cost because the amount of sodium hydroxide added to the reaction tank is small. Therefore, the present invention, as a method of treating fluorine-containing wastewater that eliminates the conventional problems,
The areas that contribute to the development of industry are extremely large.
【図１】本発明の実施の形態を示す処理フロー図であ
る。FIG. 1 is a processing flow chart showing an embodiment of the present invention.
【図２】従来例を示す処理フロー図である。FIG. 2 is a processing flow chart showing a conventional example.
【図３】従来例を示す処理フロー図である。FIG. 3 is a processing flow chart showing a conventional example.
フロントページの続き (72)発明者 加藤 達也 愛知県東海市東海町５−３ 新日本製鐵株 式会社名古屋製鐵所内 Ｆターム(参考） 4D002 AA02 AB01 AC01 BA02 BA04 DA06 DA12 EA07 4D024 AA04 AB11 BA12 BC04 DA03 DA04 DB12 DB20 DB21 4D038 AA08 AB40 AB41 BA04 BA06 BB06 BB13 BB18 Continued front page (72) Inventor Tatsuya Kato 5-3 Tokai-cho, Tokai-shi, Aichi Nippon Steel Corporation Ceremony Company Nagoya Steel Works F-term (reference) 4D002 AA02 AB01 AC01 BA02 BA04 DA06 DA12 EA07 4D024 AA04 AB11 BA12 BC04 DA03 DA04 DB12 DB20 DB21 4D038 AA08 AB40 AB41 BA04 BA06 BB06 BB13 BB18
Claims (4)
た脱硫装置から排出される排水を、ｐＨ調整槽でｐＨ調
整を行った後、反応槽で排水中に含まれるフッ素を沈殿
化合物に吸着させて凝集沈殿により除去処理するように
したフッ素含有排水の処理方法であって、ｐＨ調整槽の
後段において水酸化カルシウムを添加することによりフ
ッ化カルシウムを生成後、脱水スラリーとしてフッ素の
一部を系外へ取り出す一方、反応槽に水酸化ナトリウム
を加えることによりフッ素を吸着した塩基性硫酸マグネ
シウムおよび水酸化マグネシウムを生成させた後、これ
らを含んだスラリーをｐＨ調整槽に返送してスラリー中
の水酸化マグネシウムを酸と反応させて溶解し処理水と
して排出するとともに、塩基性硫酸マグネシウムのフッ
素吸着度を高め、この返送サイクルにより最終的にはフ
ッ素を十分に吸着した塩基性硫酸マグネシウムを含んだ
スラリーを脱水後、脱水スラリーとしてフッ素の残部を
系外へ取り出すことを特徴とするフッ素含有排水の処理
方法。1. The pH of waste water discharged from a desulfurization apparatus using magnesium hydroxide as an adsorbent is adjusted in a pH adjusting tank, and then the fluorine contained in the waste water is adsorbed by the precipitation compound in the reaction tank. A method for treating fluorine-containing wastewater that is subjected to removal treatment by coagulation sedimentation, in which calcium fluoride is produced by adding calcium hydroxide in the latter stage of the pH adjustment tank, and then a portion of fluorine is removed from the system as dehydrated slurry. On the other hand, sodium hydroxide is added to the reaction tank to generate basic magnesium sulfate and magnesium hydroxide having adsorbed fluorine, and then the slurry containing these is returned to the pH adjustment tank to return the hydroxide in the slurry. Magnesium is reacted with an acid to dissolve it and discharge it as treated water, while increasing the degree of fluorine adsorption of basic magnesium sulfate. The method for treating fluorine-containing wastewater is characterized in that, finally, the slurry containing basic magnesium sulfate sufficiently adsorbing fluorine is dehydrated by the return cycle of step 1, and the remainder of fluorine is taken out of the system as dehydrated slurry.
からスラリー脱水までの間に行う請求項１に記載のフッ
素含有排水の処理方法。2. The method for treating fluorine-containing wastewater according to claim 1, wherein calcium hydroxide is added between after pH adjustment and before slurry dehydration.
調整する請求項１または２に記載のフッ素含有排水の処
理方法。3. The method for treating fluorine-containing wastewater according to claim 1, wherein the pH of the pH adjusting tank is adjusted to be in a neutral range.
する請求項１または２または３に記載のフッ素含有排水
の処理方法。4. The method for treating fluorine-containing wastewater according to claim 1, 2 or 3, wherein the pH of the reaction tank is adjusted to 8 or higher.
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| JP2005125153A (en) * | 2003-10-21 | 2005-05-19 | Kurita Water Ind Ltd | Method and apparatus for treating fluorine-containing waste water |
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| CN113603252A (en) * | 2021-04-06 | 2021-11-05 | 河北科技大学 | Coal gasification high-concentration fluorine-containing wastewater treatment process |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005125153A (en) * | 2003-10-21 | 2005-05-19 | Kurita Water Ind Ltd | Method and apparatus for treating fluorine-containing waste water |
| JP4508600B2 (en) * | 2003-10-21 | 2010-07-21 | 栗田工業株式会社 | Method and apparatus for treating fluorine-containing wastewater |
| CN109052854A (en) * | 2018-09-06 | 2018-12-21 | 浙江海河环境科技有限公司 | A kind of solar battery mono-crystal making herbs into wool fluoride waste advanced treatment process |
| CN110862172A (en) * | 2019-12-27 | 2020-03-06 | 西安西热水务环保有限公司 | Comprehensive purification system and method for desulfurization wastewater by limestone-gypsum method |
| CN113023952A (en) * | 2021-03-24 | 2021-06-25 | 福建省长汀金龙稀土有限公司 | Rare earth molten salt electrolysis fluorine-containing wastewater treatment method |
| CN113603252A (en) * | 2021-04-06 | 2021-11-05 | 河北科技大学 | Coal gasification high-concentration fluorine-containing wastewater treatment process |
| CN114455776A (en) * | 2021-12-21 | 2022-05-10 | 中煤科工集团杭州研究院有限公司 | Stainless steel pickling wastewater treatment method based on biological denitrification |
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