JPH09886A - Treatment device for flue gas desulfurization waste water - Google Patents
Treatment device for flue gas desulfurization waste waterInfo
- Publication number
- JPH09886A JPH09886A JP15600495A JP15600495A JPH09886A JP H09886 A JPH09886 A JP H09886A JP 15600495 A JP15600495 A JP 15600495A JP 15600495 A JP15600495 A JP 15600495A JP H09886 A JPH09886 A JP H09886A
- Authority
- JP
- Japan
- Prior art keywords
- carbonate
- calcium
- flue gas
- water
- gas desulfurization
- 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.)
- Pending
Links
Landscapes
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は排煙脱硫排水の処理装置
に係り、特に、排煙脱硫装置から排出される排水に含ま
れるフッ素や重金属を消石灰などのカルシウム化合物で
処理することによりフッ化カルシウム或いは水酸化物と
して不溶化させ、不溶化物を膜分離処理する装置に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flue gas desulfurization wastewater treatment apparatus, and more particularly, to a method for treating fluorine or heavy metals contained in wastewater discharged from a flue gas desulfurization apparatus with a calcium compound such as slaked lime. The present invention relates to a device for insolubilizing calcium or hydroxide and performing a membrane separation treatment on the insoluble matter.
【0002】[0002]
【従来の技術】石炭などを燃料とした燃焼排ガスは、石
灰石膏法による排煙脱硫装置により、煤塵及び硫黄酸化
物が除去された後、放出されるが、その際、燃料由来の
フッ素、硫酸イオン、塩化物イオン、重金属イオン等を
含む排煙脱硫排水が排出される。2. Description of the Related Art Combustion exhaust gas that uses coal as a fuel is discharged after soot and sulfur oxides are removed by a flue gas desulfurization device using the limestone gypsum method. Flue gas desulfurization wastewater containing ions, chloride ions, heavy metal ions, etc. is discharged.
【0003】従来、排煙脱硫排水中のフッ素、重金属イ
オンを除去する方法として、排水に石灰乳又は消石灰粉
を加えてpHを7以上とし、フッ素イオンを難溶性のフ
ッ化カルシウムとして、また、重金属イオンを難溶性の
水酸化物としてそれぞれ不溶化させ、固液分離する方法
がある。この固液分離手段としては、沈降分離法、膜分
離法がある。Conventionally, as a method for removing fluorine and heavy metal ions in flue gas desulfurization wastewater, lime milk or slaked lime powder is added to the wastewater to adjust the pH to 7 or higher, and the fluoride ions are converted into sparingly soluble calcium fluoride. There is a method in which heavy metal ions are made insoluble as insoluble hydroxides and solid-liquid separation is performed. As the solid-liquid separation means, there are a sedimentation separation method and a membrane separation method.
【0004】[0004]
【発明が解決しようとする課題】排煙脱硫排水にカルシ
ウム化合物を添加して不溶化処理した後、不溶化物を膜
分離により固液分離する場合、膜透過流束の低下が起き
易く、安定かつ効率的な処理を行うことができないとい
う問題がある。即ち、排煙脱硫排水にカルシウム化合物
を添加する不溶化処理で得られる不溶化物中には、排煙
脱硫排水中の硫酸イオンがカルシウム化合物との反応で
生成した石膏として存在するが、この石膏が膜透過流束
を低下させる原因となる。When a calcium compound is added to flue gas desulfurization wastewater to insolubilize it, and then the insoluble matter is subjected to solid-liquid separation by membrane separation, the membrane permeation flux is apt to decrease, resulting in stable and efficient treatment. There is a problem that it is not possible to perform specific processing. That is, in the insolubilized product obtained by the insolubilization treatment in which a calcium compound is added to the flue gas desulfurization wastewater, sulfate ions in the flue gas desulfurization wastewater exist as gypsum produced by the reaction with the calcium compound, but this gypsum is a film. This causes a decrease in permeation flux.
【0005】本発明は上記従来の実情に鑑みてなされた
ものであって、排煙脱硫排水中のフッ素や重金属イオン
を消石灰等のカルシウム化合物で不溶化し、生成した不
溶化物を膜分離により固液分離するに当り、不溶化物中
の石膏に起因する膜透過流束の低下を防止して、長期に
わたり安定かつ効率的な処理を行える排煙脱硫排水の処
理装置を提供することを目的とする。The present invention has been made in view of the above conventional circumstances, in which fluorine and heavy metal ions in flue gas desulfurization wastewater are insolubilized with a calcium compound such as slaked lime, and the insolubilized product thus formed is solid-liquid separated by membrane separation. An object of the present invention is to provide a flue gas desulfurization wastewater treatment apparatus which can prevent a decrease in membrane permeation flux due to gypsum in an insoluble matter and can perform stable and efficient treatment for a long time upon separation.
【0006】[0006]
【課題を解決するための手段】本発明の排煙脱硫排水の
処理装置は、排煙脱硫排水に炭酸塩を添加して炭酸カル
シウムの析出物を分離する炭酸カルシウム分離手段と、
該炭酸カルシウム分離手段で炭酸カルシウムを分離した
水にカルシウム化合物を添加して不溶化物を析出させる
不溶化物析出手段と、該不溶化物析出手段で得られた水
を膜分離処理する膜モジュールとを備えてなることを特
徴とする。A treatment apparatus for flue gas desulfurization wastewater according to the present invention comprises a calcium carbonate separation means for adding a carbonate to the flue gas desulfurization wastewater to separate calcium carbonate deposits.
An insoluble matter depositing means for depositing an insoluble matter by adding a calcium compound to water separated from the calcium carbonate by the calcium carbonate separating means, and a membrane module for subjecting the water obtained by the insoluble matter depositing means to a membrane separation treatment are provided. It is characterized by
【0007】本発明者らは、排煙脱硫排水の不溶化及び
不溶化物の膜分離処理における不溶化物中の石膏に起因
する膜透過流束の低下の問題につき検討を重ねた結果、
不溶化物中に大粒径(例えば、粒径100μm以上)の
石膏粒子が多く存在すると膜透過流束の低下が著しいこ
とを見出した。As a result of repeated investigations by the inventors of the present invention, the problems of insolubilization of flue gas desulfurization wastewater and reduction of membrane permeation flux due to gypsum in the insoluble matter in the membrane separation treatment of the insoluble matter were obtained.
It has been found that when a large amount of gypsum particles having a large particle size (for example, a particle size of 100 μm or more) is present in the insoluble matter, the membrane permeation flux is significantly reduced.
【0008】また、排煙脱硫排水に炭酸ナトリウムなど
の炭酸塩を添加すると、排水中のカルシウムイオンは炭
酸カルシウムとして不溶化するため、排水のカルシウム
イオン濃度が低下すること、更に、カルシウムイオン濃
度が低い排水を消石灰で中和した場合には、石膏の析出
量が低下すると共に、析出する石膏の粒径も小さくなる
ことを見出した。Further, when a carbonate such as sodium carbonate is added to the flue gas desulfurization wastewater, calcium ions in the wastewater are insolubilized as calcium carbonate, so that the calcium ion concentration of the wastewater is lowered and further the calcium ion concentration is low. It was found that when the wastewater was neutralized with slaked lime, the amount of gypsum deposited was reduced and the particle size of the gypsum deposited was also reduced.
【0009】本発明は上記知見に基いて達成されたもの
であり、予め、炭酸塩処理で排水のカルシウムイオン濃
度を下げることにより、膜透過流束低下の原因となる大
粒径の石膏粒子の生成を防止して膜分離処理の安定化を
図るものである。The present invention has been achieved based on the above findings. In advance, by reducing the calcium ion concentration of waste water by carbonate treatment, it is possible to obtain gypsum particles of large particle size that cause a decrease in membrane permeation flux. It is intended to prevent the generation and stabilize the membrane separation process.
【0010】[0010]
【作用】排煙脱硫排水にカルシウム化合物を添加してフ
ッ素や重金属イオンを不溶化するに先立ち、排煙脱硫排
水に炭酸塩を添加して炭酸カルシウムを析出させ、析出
した炭酸カルシウムを分離除去することにより、排水中
のカルシウムイオン濃度を低減する。このカルシウムイ
オン濃度を低減した排水に対して、カルシウム化合物を
添加することにより、膜透過流束低下の原因となる石膏
の粗大粒子の生成を抑制すると共に、石膏の析出量を低
減することができる。[Function] Prior to adding a calcium compound to the flue gas desulfurization wastewater to insolubilize fluorine and heavy metal ions, a carbonate is added to the flue gas desulfurization wastewater to precipitate calcium carbonate, and the precipitated calcium carbonate is separated and removed. This reduces the calcium ion concentration in the wastewater. By adding a calcium compound to the wastewater having a reduced calcium ion concentration, it is possible to suppress the generation of coarse particles of gypsum, which causes a decrease in membrane permeation flux, and reduce the amount of gypsum deposited. .
【0011】このため、膜モジュールに流入する石膏粒
子は小さくかつその流入量も少ないものとなり、膜モジ
ュールの膜透過流束の低下は防止され、膜透過流束を長
期にわたり安定に維持することが可能となる。Therefore, the gypsum particles flowing into the membrane module are small and the inflow amount is small, the decrease of the membrane permeation flux of the membrane module is prevented, and the membrane permeation flux can be stably maintained for a long period of time. It will be possible.
【0012】[0012]
【実施例】以下、図面を参照して本発明の実施例につき
詳細に説明する。Embodiments of the present invention will now be described in detail with reference to the drawings.
【0013】図1は本発明の排煙脱硫排水の処理装置の
一実施例を示す系統図である。FIG. 1 is a system diagram showing an embodiment of a flue gas desulfurization wastewater treatment apparatus according to the present invention.
【0014】本実施例において、フッ素、硫酸イオン及
び重金属イオンを含む排煙脱硫排水は、配管11よりま
ず炭酸塩処理槽1に導入され、炭酸塩貯槽2内の炭酸塩
が配管12より添加され、これにより、排水中のカルシ
ウムイオンが炭酸カルシウム(CaCO3 )として析出
する。In this embodiment, the flue gas desulfurization wastewater containing fluorine, sulfate ions and heavy metal ions is first introduced into the carbonate treatment tank 1 through the pipe 11, and the carbonate in the carbonate storage tank 2 is added through the pipe 12. As a result, calcium ions in the waste water are precipitated as calcium carbonate (CaCO 3 ).
【0015】この炭酸塩処理槽1は、底部が下方へ向っ
て縮径する逆円錐形状とされ、その下端に沈降析出物の
引抜き配管13が設けられている。炭酸塩処理槽1内に
は、槽内を完全混合条件とするために、撹拌機1Aが設
けられているが、この撹拌機1Aの撹拌を緩速撹拌とす
ることにより、炭酸カルシウムの析出物を沈降させるこ
とができる。沈降した析出物は槽下部の沈降析出物の引
抜き配管13より系外へ排出される。The carbonate treatment tank 1 has an inverted conical shape in which the bottom portion is reduced in diameter downward, and a withdrawing pipe 13 for the sedimentation precipitate is provided at the lower end thereof. A stirrer 1A is provided in the carbonate treatment tank 1 in order to bring the inside of the tank into a complete mixing condition. However, by stirring the stirrer 1A slowly, a precipitate of calcium carbonate can be obtained. Can be allowed to settle. The sedimented precipitate is discharged to the outside of the system through a pipe 13 for extracting the sedimented sediment at the bottom of the tank.
【0016】炭酸塩処理槽1の流出水は、配管14より
不溶化処理槽3に導入され、消石灰貯槽4内の消石灰が
配管15より添加され、pH7以上に調整される。これ
により、フッ素は難溶性のフッ化カルシウム(CaF
2 )として、また、重金属イオンは難溶性の水酸化物と
して不溶化し、同時に、排水中に共存する硫酸イオンが
石膏(CaSO4 ・2H2 O)として析出するが、この
析出に当り、系内のカルシウムイオン濃度が低いことか
ら、石膏結晶の析出及びその成長が抑制され、粒径10
0μm以上の大粒径の結晶の析出は防止される。The outflow water of the carbonate treatment tank 1 is introduced into the insolubilization treatment tank 3 through the pipe 14, the slaked lime in the slaked lime storage tank 4 is added through the pipe 15, and the pH is adjusted to 7 or higher. As a result, fluorine is hardly soluble in calcium fluoride (CaF
2 ) Also, heavy metal ions are insolubilized as sparingly soluble hydroxides, and at the same time, sulfate ions coexisting in the waste water are precipitated as gypsum (CaSO 4 · 2H 2 O). Since the calcium ion concentration of the gypsum is low, the precipitation and growth of gypsum crystals are suppressed, and the particle size is 10
Precipitation of crystals having a large grain size of 0 μm or more is prevented.
【0017】従って、配管16より循環槽5に流入する
不溶化処理槽3の流出水中の石膏析出粒子量は少なく、
しかも、析出した石膏粒子も例えば粒径30μm以下と
いった小粒径のものが中心となるため、膜モジュール6
の膜透過流束低下は起こりにくくなる。Therefore, the amount of gypsum-precipitated particles in the outflow water of the insolubilization treatment tank 3 flowing into the circulation tank 5 from the pipe 16 is small,
Moreover, the gypsum particles that have been deposited are mainly those having a small particle size of, for example, 30 μm or less.
The decrease in the membrane permeation flux is less likely to occur.
【0018】不溶化処理槽3の流出水は、配管16、循
環槽5及び配管17を経て膜モジュール6に導入され、
不溶化物が膜で捕捉され、透過水は配管18より処理水
として系外へ排出される。一方、濃縮水は配管19より
循環槽5に循環され、一部は配管20から系外に排出さ
れる。The water discharged from the insolubilization treatment tank 3 is introduced into the membrane module 6 through the pipe 16, the circulation tank 5 and the pipe 17,
The insoluble matter is captured by the membrane, and the permeated water is discharged from the system as treated water through the pipe 18. On the other hand, the concentrated water is circulated through the pipe 19 to the circulation tank 5, and a part of the concentrated water is discharged out of the system through the pipe 20.
【0019】この膜モジュール6としては、UF(限外
濾過)膜やMF(精密濾過)膜を設けたクロスフロー型
膜モジュールが好適である。As the membrane module 6, a cross-flow type membrane module provided with a UF (ultrafiltration) membrane or an MF (microfiltration) membrane is suitable.
【0020】本発明において、炭酸塩としては、炭酸ナ
トリウム、炭酸アンモニウム、炭酸バリウム、重炭酸ナ
トリウム等を用いることができる。炭酸塩の添加濃度は
炭酸濃度として排煙脱硫排水に対して1000mg/l
以上、通常は1000〜2000mg/lとするのが好
ましく、この炭酸塩の添加により、排水中のカルシウム
イオン濃度を250mg/l以下に低減するのが望まし
い。In the present invention, as the carbonate, sodium carbonate, ammonium carbonate, barium carbonate, sodium bicarbonate or the like can be used. The concentration of carbonate added is 1000 mg / l for flue gas desulfurization wastewater as carbon dioxide concentration.
As described above, it is usually preferable to set the concentration to 1000 to 2000 mg / l, and it is desirable to reduce the calcium ion concentration in the waste water to 250 mg / l or less by adding this carbonate.
【0021】カルシウム化合物としては、上記消石灰
(Ca(OH)2 )を用い、添加後の排水のpHが7.
0以上となるように、必要に応じて他のpH調整剤と共
に添加される。As the calcium compound, the above slaked lime (Ca (OH) 2 ) is used, and the pH of the waste water after addition is 7.
If necessary, it is added together with another pH adjuster so as to be 0 or more.
【0022】以下に具体的な実施例及び比較例を挙げ
て、本発明をより詳細に説明する。The present invention will be described in more detail with reference to specific examples and comparative examples.
【0023】実施例1 図1に示す本発明の排煙脱硫排水の処理装置により、表
1に示す水質の排煙脱硫排水を処理した。Example 1 The flue gas desulfurization wastewater having the water quality shown in Table 1 was treated by the flue gas desulfurization wastewater treatment apparatus of the present invention shown in FIG.
【0024】[0024]
【表1】 [Table 1]
【0025】炭酸塩としては炭酸ナトリウムを使用し、
添加濃度は排煙脱硫排水に対して炭酸濃度として100
0mg/lとし、析出した炭酸カルシウムを引き抜くこ
とにより、炭酸塩処理槽の流出水のカルシウムイオン濃
度を約200mg/lとした。また、消石灰は添加後の
pHが7.0となるように添加した。膜モジュールとし
てはポリプロピレン製のクロスフロー型MF膜モジュー
ルを用いた。Sodium carbonate is used as the carbonate,
Addition concentration is 100 as carbon dioxide concentration for flue gas desulfurization wastewater.
The calcium ion concentration was set to 0 mg / l, and the precipitated calcium carbonate was extracted to adjust the calcium ion concentration of the outflow water of the carbonate treatment tank to about 200 mg / l. Also, slaked lime was added so that the pH after addition was 7.0. As the membrane module, a polypropylene cross-flow type MF membrane module was used.
【0026】その他の処理条件は下記の通りとした。The other processing conditions were as follows.
【0027】処理条件 排煙脱硫排水処理水量:180L/day 膜面積:0.036m2 循環水(濃縮水)量:8.4L/hr 反応槽,循環槽滞留時間:2.5hr 処理開始初期及び30日後の膜透過流束を表2に示す。
また、処理開始から30日後の循環槽内の析出物の平均
粒径を調べ、結果を表2に示した。 Treatment conditions Flue gas desulfurization wastewater Treatment water amount: 180 L / day Membrane area: 0.036 m 2 Circulating water (concentrated water) amount: 8.4 L / hr Reactor tank, circulation tank residence time: 2.5 hr Initial treatment start and The membrane permeation flux after 30 days is shown in Table 2.
Further, the average particle size of the precipitate in the circulation tank was examined 30 days after the start of the treatment, and the results are shown in Table 2.
【0028】比較例1 炭酸塩処理槽を設けず、排煙脱硫排水を直接不溶化処理
槽に導入したこと以外は実施例1と同様に行って、処理
開始直後及び30日後の膜透過流束及び30日後の循環
槽内の析出物の平均粒径を調べ、結果を表2に示した。Comparative Example 1 The same procedure as in Example 1 was carried out except that the flue gas desulfurization effluent was directly introduced into the insolubilization treatment tank without providing the carbonate treatment tank, and the membrane permeation flux and The average particle size of precipitates in the circulation tank after 30 days was examined, and the results are shown in Table 2.
【0029】[0029]
【表2】 [Table 2]
【0030】表2より、予め炭酸塩を添加して排水中の
カルシウムイオンを炭酸カルシウムとして除去すること
により、結晶成長が抑制され、これにより、膜透過流束
の低下が防止されて、膜透過流束が高く維持されること
が明らかである。From Table 2, by adding a carbonate in advance to remove the calcium ions in the waste water as calcium carbonate, the crystal growth is suppressed, whereby the reduction of the membrane permeation flux is prevented and the membrane permeation flux is prevented. It is clear that the flux remains high.
【0031】[0031]
【発明の効果】以上詳述した通り、本発明の排煙脱硫排
水の処理装置によれば、排煙脱硫排水をカルシウム化合
物により不溶化処理して不溶化物を膜分離処理により固
液分離するに当り、膜透過流束の低下を防止して、長期
にわたり安定かつ効率的な処理を行うことができる。As described in detail above, according to the flue gas desulfurization wastewater treatment apparatus of the present invention, the flue gas desulfurization wastewater is insolubilized with the calcium compound and the insoluble matter is subjected to solid-liquid separation by the membrane separation treatment. Thus, it is possible to prevent a decrease in the membrane permeation flux and perform stable and efficient treatment for a long period of time.
【図1】本発明の排煙脱硫排水の処理装置の一実施例を
示す系統図である。FIG. 1 is a system diagram showing an embodiment of a flue gas desulfurization wastewater treatment apparatus according to the present invention.
1 炭酸塩処理槽 2 炭酸塩貯槽 3 不溶化処理槽 4 消石灰貯槽 5 循環槽 6 膜モジュール 1 Carbonate treatment tank 2 Carbonate storage tank 3 Insolubilization treatment tank 4 Slaked lime storage tank 5 Circulation tank 6 Membrane module
Claims (1)
ルシウムの析出物を分離する炭酸カルシウム分離手段
と、該炭酸カルシウム分離手段で炭酸カルシウムを分離
した水にカルシウム化合物を添加して不溶化物を析出さ
せる不溶化物析出手段と、該不溶化物析出手段で得られ
た水を膜分離処理する膜モジュールとを備えてなる排煙
脱硫排水の処理装置。1. A calcium carbonate separation means for adding a carbonate to flue gas desulfurization effluent to separate calcium carbonate precipitates, and a calcium compound added to the water from which calcium carbonate has been separated by the calcium carbonate separation means to insolubilize it. An apparatus for treating flue gas desulfurization wastewater, comprising an insoluble matter depositing means for depositing a substance and a membrane module for subjecting the water obtained by the insoluble matter depositing means to a membrane separation treatment.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP15600495A JPH09886A (en) | 1995-06-22 | 1995-06-22 | Treatment device for flue gas desulfurization waste water |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP15600495A JPH09886A (en) | 1995-06-22 | 1995-06-22 | Treatment device for flue gas desulfurization waste water |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH09886A true JPH09886A (en) | 1997-01-07 |
Family
ID=15618233
Family Applications (1)
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JP15600495A Pending JPH09886A (en) | 1995-06-22 | 1995-06-22 | Treatment device for flue gas desulfurization waste water |
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JP (1) | JPH09886A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103288178A (en) * | 2013-06-24 | 2013-09-11 | 北京赛科康仑环保科技有限公司 | A low-energy consumption desalination process for wastewater and an apparatus thereof |
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1995
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103288178A (en) * | 2013-06-24 | 2013-09-11 | 北京赛科康仑环保科技有限公司 | A low-energy consumption desalination process for wastewater and an apparatus thereof |
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