JP2001121162A - Method for reduction treatment of hexavalent chromium in heavy metal, waste liquid - Google Patents
Method for reduction treatment of hexavalent chromium in heavy metal, waste liquidInfo
- Publication number
- JP2001121162A JP2001121162A JP30804999A JP30804999A JP2001121162A JP 2001121162 A JP2001121162 A JP 2001121162A JP 30804999 A JP30804999 A JP 30804999A JP 30804999 A JP30804999 A JP 30804999A JP 2001121162 A JP2001121162 A JP 2001121162A
- Authority
- JP
- Japan
- Prior art keywords
- waste liquid
- hexavalent chromium
- heavy metal
- reduction
- reduction treatment
- 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.)
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- Treatment Of Water By Oxidation Or Reduction (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、例えば、精錬工業
や化学実験場等から発生する各種有害重金属を高濃度に
含有する廃液に含まれる６価クロム化合物を効果的に還
元処理することにより、最終処分体の減容化と処理費用
の節減を達成できるようにした、廃液中の６価クロムの
還元処理方法に関するものである。BACKGROUND OF THE INVENTION The present invention relates to a method for effectively reducing a hexavalent chromium compound contained in a waste liquid containing a high concentration of various harmful heavy metals generated from, for example, a refining industry or a chemical laboratory. The present invention relates to a method for reducing hexavalent chromium in waste liquid, which can achieve a reduction in volume of a final disposal body and a reduction in processing costs.
【０００２】[0002]
【従来の技術】重金属含有廃液の処理方法として、現在
最も広く普及している方法は、中和処理による水酸化物
沈殿法である。この方法の場合、廃液中の６価クロムイ
オンは、安定な陰イオン（ＣｒＯ4 2-、Ｃｒ2Ｏ7 2-）と
して存在し、他の重金属類と異なり、水酸化物沈殿法で
除去できないので、３価クロムへの還元処理が行われて
いる。６価クロムイオンの還元方法として、亜硫酸塩又
は第一鉄塩を使用する方法の場合、多量の硫酸塩や水酸
化鉄を含むスラッジが発生することにより最終処分体が
増加したり、またＯＲＰ計による薬注制御が複雑で処理
の安定性に欠けるなどの欠点がある。還元剤として亜硫
酸塩又は第一鉄塩を使用する場合、６価クロム塩の還元
反応式と理論薬品量は下記の通りである。2. Description of the Related Art The most widespread method for treating heavy metal-containing waste liquid at present is a hydroxide precipitation method by neutralization treatment. In this method, hexavalent chromium ions in the waste liquid are present as stable anions (CrO 4 2− , Cr 2 O 7 2− ) and cannot be removed by the hydroxide precipitation method unlike other heavy metals. Therefore, reduction treatment to trivalent chromium is performed. In the case of using sulfite or ferrous salt as a method for reducing hexavalent chromium ions, sludge containing a large amount of sulfate or iron hydroxide is generated, thereby increasing the number of final disposal bodies and increasing the ORP meter. There are drawbacks such as complicated drug injection control due to lack of stability of treatment. When a sulfite or a ferrous salt is used as the reducing agent, the reduction reaction formula and theoretical amount of the hexavalent chromium salt are as follows.
【０００３】[0003]
【表１】 [Table 1]
【０００４】また、６価クロムの還元は、電解処理によ
っても行うことができるが、発生水素ガスによる火災や
爆発等の危険性もあり、装置コストも高く、また、高濃
度廃液では電力消費量が膨大で不利な場合が多い。[0004] The reduction of hexavalent chromium can also be performed by electrolytic treatment, but there is a risk of fire or explosion due to the generated hydrogen gas, the equipment cost is high, and the power consumption of highly concentrated waste liquid is high. Is often enormous and disadvantageous.
【０００５】[0005]
【発明が解決しようとする課題】本発明の目的は、上記
のような従来技術の欠点を解消し、確実で単純なプロセ
スにより、重金属含有廃液中の６価クロムイオンを還元
処理することにより、最終処分体の量をできるだけ少な
くし、かつ、処理処分コストの削減を図ることができ
る、廃液中の６価クロムの還元処理方法を提供する。SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art and reduce the hexavalent chromium ions in the heavy metal-containing waste liquid by a reliable and simple process. Provided is a method for reducing hexavalent chromium in a waste liquid, in which the amount of a final disposal body can be reduced as much as possible and the disposal cost can be reduced.
【０００６】[0006]
【課題を解決するための手段】上記目的達成のため、本
発明者らは、還元剤として、過酸化水素（Ｈ2Ｏ2）又は
ヒドラジン(Ｎ2Ｈ4）を用いることを特徴とする重金属
廃液中の６価クロムの還元処理方法を開発した。還元剤
として過酸化水素(Ｈ2Ｏ2)を用いる場合は、７０ｍｍｏ
ｌ／Ｌ以上添加するのが望ましく、還元剤としてヒドラ
ジン(Ｎ2Ｈ4）を用いる場合は、１８ｍｍｏｌ／Ｌ以上
添加するのが望ましい。本発明の還元処理方法は、簡単
な装置で簡単な操作により行うことができ、かつ爆発等
の危険もなく、安価な還元剤を用いるため、処理コスト
も安い。また、高濃度の廃液でも、還元剤の量を調節す
ることにより処理できるため処理効率も高い。さらに、
本方法では、従来法に比べ、最終処分体を減容できる。Means for Solving the Problems In order to achieve the above object, the present inventors have developed a heavy metal using hydrogen peroxide (H 2 O 2 ) or hydrazine (N 2 H 4 ) as a reducing agent. A method for reducing hexavalent chromium in waste liquid has been developed. When using hydrogen peroxide (H 2 O 2 ) as the reducing agent, 70 mmo
1 / L or more is desirable, and when hydrazine (N 2 H 4 ) is used as a reducing agent, it is desirable to add 18 mmol / L or more. The reduction treatment method of the present invention can be performed by a simple operation with a simple apparatus, does not cause explosion or the like, and uses an inexpensive reducing agent, so that the treatment cost is low. Further, even a high-concentration waste liquid can be treated by adjusting the amount of the reducing agent, so that the treatment efficiency is high. further,
In this method, the volume of the final disposal body can be reduced as compared with the conventional method.
【０００７】[0007]
【発明の実施の形態】図１は、本発明の処理方法により
廃液の６価クロムを還元処理する場合に用いることがで
きるシステムのフローの例を示すものである。このシス
テムは、精錬工場や化学実験場等から発生する、各種重
金属を高濃度に含有する廃液を一時的に貯留するための
廃液貯留槽（Ｓ−１）と、廃液貯留槽から送られた廃液
中の６価クロムを還元処理するための還元槽（Ｓ−２）
と、還元槽により排出された還元後の廃液を中和沈殿処
理するための中和槽（Ｓ−３）と、中和槽より排出され
た廃液中の水酸化物沈殿と処理水を分離するための凝集
沈殿槽（Ｓ−４）とを含むものである。このシステムで
は、凝集沈殿槽の後段に、水酸化物沈殿の脱水濃縮設備
（Ｓ−５）を必要に応じて設置することができる。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a flow of a system that can be used when reducing hexavalent chromium in a waste liquid by the treatment method of the present invention. This system has a waste liquid storage tank (S-1) for temporarily storing waste liquid containing various heavy metals at a high concentration, which is generated from a smelting plant or a chemical laboratory, and a waste liquid sent from the waste liquid storage tank. Reduction tank (S-2) for reducing hexavalent chromium inside
And a neutralization tank (S-3) for neutralizing and precipitating the waste liquid after reduction discharged from the reduction tank, and separating the hydroxide precipitate and the treated water in the waste liquid discharged from the neutralization tank. And a coagulation sedimentation tank (S-4). In this system, a dehydration / concentration facility (S-5) for hydroxide precipitation can be installed as necessary at the subsequent stage of the coagulation sedimentation tank.
【０００８】本方法においては、還元槽にｐＨ計を設
け、ｐＨを測定し、必要に応じてｐＨを調節しつつ還元
処理を行うことができる。過酸化水素（Ｈ2Ｏ2）を還元
剤として用いた場合は、６価クロムの還元率が廃液のｐ
Ｈに影響を受けることから、ｐＨの測定を行いつつ還元
処理することが好ましい。また、還元処理後の中和処理
においても、中和反応の制御のため、中和槽にｐＨ計を
設け、投与するアルカリ薬剤の量を調節することが好ま
しい。本発明では、還元剤として過酸化水素(Ｈ2Ｏ2）
又はヒドラジン（Ｎ2Ｈ4）を廃液に投与することによ
り、廃液中の６価クロムを３価クロムに還元処理する。
その後、還元処理後の廃液にアルカリ薬剤、例えば、Ｎ
ａＯＨ、Ｃａ（ＯＨ）2、ＫＯＨ、ＬｉＯＨ等を添加し
て中和し、凝集沈殿させ、重金属の水酸化物スラリーと
して最終処分体とする。In this method, a pH meter is provided in the reduction tank, the pH is measured, and the reduction treatment can be performed while adjusting the pH as needed. When hydrogen peroxide (H 2 O 2 ) is used as a reducing agent, the reduction rate of hexavalent chromium is reduced by
Since it is affected by H, it is preferable to perform the reduction treatment while measuring the pH. Also, in the neutralization treatment after the reduction treatment, it is preferable to provide a pH meter in the neutralization tank and control the amount of the alkaline agent to be administered in order to control the neutralization reaction. In the present invention, hydrogen peroxide (H 2 O 2 ) is used as a reducing agent.
Alternatively, hydrazine (N 2 H 4 ) is administered to the waste liquid to reduce hexavalent chromium in the waste liquid to trivalent chromium.
Then, an alkaline agent such as N
aOH, Ca (OH) 2 , KOH, LiOH, etc. are added to neutralize, coagulate and precipitate, and form a final disposal body as a heavy metal hydroxide slurry.
【０００９】[0009]
【実施例】以下に実施例を挙げて、本発明をさらに詳細
に説明するが、これらにより本発明を制限するものでは
ない。実施例１ 本発明による廃液中の６価クロムの還元及び中和沈殿処
理方法は、前記処理手段に基づいて行われるが、本発明
の効果を下記に示すような実験室段階でのシュミレーシ
ョンにより確認した。重金属含有廃液を類似するものと
して、試薬を用いて模擬廃液を調製し、その模擬廃液を
用いて本発明の効果を検証した。模擬廃液の組成は表２
に示すとおりである。EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. Example 1 The method of reducing and neutralizing and precipitating hexavalent chromium in a waste liquid according to the present invention is performed based on the above-mentioned processing means. The effects of the present invention were confirmed by simulation in a laboratory as shown below. did. A simulated waste liquid was prepared using reagents assuming that the heavy metal-containing waste liquid was similar, and the effect of the present invention was verified using the simulated waste liquid. Table 2 shows the composition of the simulated waste liquid.
As shown in FIG.
【００１０】[0010]
【表２】 [Table 2]
【００１１】前記表２の模擬廃液のうち、表中ｂとｃの
２種類の模擬排水に、還元剤として過酸化水素（Ｈ
2Ｏ2）を３０ｍｍｏｌ／Ｌから３００ｍｍｏｌ／Ｌの範
囲でそれぞれ添加し、室温で約６０分間撹拌しながら還
元処理を行った。この結果、図２（Ａ）に示すように、
６価クロムイオンの還元性能は、廃液のｐＨ依存性が強
く、低いｐＨ程効果的であり、廃液のｐＨが１程度の場
合、７０ｍｍｏｌ／Ｌ以上の過酸化水素（Ｈ2Ｏ2）添加
量、即ち、６価クロムイオン濃度の３倍当量以上の添加
でほぼ１００％還元できる。廃液のｐＨが２程度になる
と、還元性能が低下するので２５０ｍｍｏｌ／Ｌ以上の
添加量が必要となる。[0011] Of the simulated waste liquids shown in Table 2, two kinds of simulated wastewaters b and c in the table are supplied with hydrogen peroxide (H) as a reducing agent.
2 O 2 ) was added in the range of 30 mmol / L to 300 mmol / L, and a reduction treatment was performed while stirring at room temperature for about 60 minutes. As a result, as shown in FIG.
The hexavalent chromium ion reduction performance is strongly dependent on the pH of the waste liquid and is more effective as the pH of the waste liquid is lower. When the pH of the waste liquid is about 1, the amount of hydrogen peroxide (H 2 O 2 ) of 70 mmol / L or more is added. That is, almost 100% reduction can be achieved by adding at least three equivalents of the hexavalent chromium ion concentration. When the pH of the waste liquid is about 2, the reduction performance is reduced, so that an addition amount of 250 mmol / L or more is required.
【００１２】なお、過酸化水素（Ｈ2Ｏ2）による６価ク
ロムの理論還元反応は下記の反応式に従うので、実際は
理論必要当量の２〜７倍量の添加が必要となる。 ２Ｈ2ＣｒＯ4（６価クロム）＋３Ｈ2Ｏ2→Ｃｒ2Ｏ3（３
価クロム）＋５Ｈ2Ｏ＋３Ｏ2 なお、過酸化水素（Ｈ2Ｏ2）の場合、過剰量が廃液中に
残留しても、図３に示すように、過酸化水素（Ｈ2Ｏ2）
は常温でも分解し易く、７時間後程度でほとんど全て分
解されるので、後段の処理プロセス（中和沈殿）への影
響もなく、実用的な還元剤と考える。Since the theoretical reduction reaction of hexavalent chromium with hydrogen peroxide (H 2 O 2 ) follows the following reaction formula, it is actually necessary to add 2 to 7 times the theoretically necessary equivalent. 2H 2 CrO 4 (hexavalent chromium) + 3H 2 O 2 → Cr 2 O 3 (3
(Chromium (valent)) + 5H 2 O + 3O 2 In the case of hydrogen peroxide (H 2 O 2 ), as shown in FIG. 3, even if an excessive amount remains in the waste liquid, hydrogen peroxide (H 2 O 2 )
Is easily decomposed even at room temperature, and is almost completely decomposed in about 7 hours. Therefore, it is considered to be a practical reducing agent without affecting the subsequent treatment process (neutralization precipitation).
【００１３】実施例２ 前記過酸化水素（Ｈ2Ｏ2）をヒドラジン（Ｎ2Ｈ4）に変
更して、実施例１と同様な実験を行った結果を、図２
（Ｂ）に示す。本実施例では、表中ａ、ｂ、ｃの３種類
の模擬廃液を用いた。本図に示すように、ヒドラジン
（Ｎ2Ｈ4）を還元剤として用いた場合、還元性能のｐＨ
依存性はなく、１８ｍｍｏｌ／Ｌ以上の添加量、即ち、
６価クロム濃度と等量添加でほぼ１００％還元できる。 Example 2 The same experiment as in Example 1 was carried out except that the hydrogen peroxide (H 2 O 2 ) was changed to hydrazine (N 2 H 4 ).
It is shown in (B). In this example, three types of simulated waste liquids a, b, and c in the table were used. As shown in this figure, when hydrazine (N 2 H 4 ) was used as a reducing agent, the pH of the reducing performance was
There is no dependence, and the amount added is 18 mmol / L or more, that is,
Almost 100% reduction can be achieved by adding an equivalent amount of hexavalent chromium.
【００１４】なお、ヒドラジン（Ｎ2Ｈ4）による６価ク
ロムの理論還元反応は、下記の反応式に従う。 ２Ｈ2ＣｒＯ4（６価クロム）＋３／２Ｎ2Ｈ4→Ｃｒ2Ｏ3
（３価クロム）＋５Ｈ2Ｏ＋３／２Ｎ2 またヒドラジン（Ｎ2Ｈ4）の場合も、過剰量が廃液中に
残留しても、空気酸化により窒素ガス（Ｎ2）と水に容
易に分解されるので後段の処理プロセス（中和沈殿）へ
の影響もない。The theoretical reduction reaction of hexavalent chromium with hydrazine (N 2 H 4 ) follows the following reaction formula. 2H 2 CrO 4 (hexavalent chromium) + 3 / 2N 2 H 4 → Cr 2 O 3
In the case of (trivalent chromium) + 5H 2 O + 3 / 2N 2 or hydrazine (N 2 H 4 ), even if the excess amount remains in the waste liquid, it is easily decomposed into nitrogen gas (N 2 ) and water by air oxidation. Therefore, there is no influence on the subsequent treatment process (neutralization precipitation).
【００１５】[0015]
【発明の効果】上記したところから明らかなように、本
発明によれば、従来方法と比べ、確実で単純な制御方法
で、かつ、最終処分体（重金属の水酸化物沈殿スラリ
ー）の発生量を少なくできる廃液中の６価クロムの還元
処理方法の提供が可能となる。また、本発明の方法は、
簡単な装置により行うことができ、かつ爆発等の危険も
なく、安価な還元剤を用いるため、処理コストも安い。As is apparent from the above description, according to the present invention, compared with the conventional method, the amount of generated final disposal body (slurry of hydroxide precipitation of heavy metal) can be controlled more reliably and simply. It is possible to provide a method for reducing hexavalent chromium in waste liquid, which can reduce the amount of hexavalent chromium. Also, the method of the present invention,
The treatment can be performed with a simple device, and there is no danger of explosion or the like.
【図１】本発明の実施形態に係る重金属含有廃液の還元
−中和沈殿処理方法のフロー図である。FIG. 1 is a flowchart of a method for reducing-neutralizing and precipitating a heavy metal-containing waste liquid according to an embodiment of the present invention.
【図２】還元剤として過酸化水素（Ｈ2Ｏ2）を用いた場
合（Ａ）と、還元剤としてヒドラジン（Ｎ2Ｈ4）を用い
た場合（Ｂ）における還元剤の添加量と６価クロムの還
元率の関係を示すグラフである。FIG. 2 shows the addition amount of the reducing agent in the case where hydrogen peroxide (H 2 O 2 ) is used as the reducing agent (A) and in the case where hydrazine (N 2 H 4 ) is used as the reducing agent (B). 4 is a graph showing the relationship between the reduction ratio of chromium (valent).
【図３】過酸化水素の分解速度を示すグラフである。FIG. 3 is a graph showing a decomposition rate of hydrogen peroxide.
Claims (4)
用いることを特徴とする重金属廃液中の６価クロムの還
元処理方法。1. A method for reducing hexavalent chromium in heavy metal waste liquid, comprising using hydrogen peroxide (H 2 O 2 ) as a reducing agent.
用いることを特徴とする重金属廃液中の６価クロムの還
元処理方法。2. A method for reducing hexavalent chromium in heavy metal waste liquid, comprising using hydrazine (N 2 H 4 ) as a reducing agent.
以上添加することを特徴とする請求項１に記載の還元処
理方法。3. Hydrogen peroxide (H 2 O 2 ) is added at 70 mmol / L.
The reduction treatment method according to claim 1, wherein the above-mentioned addition is performed.
Ｌ以上添加することを特徴とする請求項２に記載の還元
処理方法。 4. A method for dissolving hydrazine (N 2 H 4 ) in an amount of 18 mmol /
The reduction treatment method according to claim 2, wherein L or more is added.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30804999A JP2001121162A (en) | 1999-10-29 | 1999-10-29 | Method for reduction treatment of hexavalent chromium in heavy metal, waste liquid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30804999A JP2001121162A (en) | 1999-10-29 | 1999-10-29 | Method for reduction treatment of hexavalent chromium in heavy metal, waste liquid |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2001121162A true JP2001121162A (en) | 2001-05-08 |
Family
ID=17976278
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30804999A Withdrawn JP2001121162A (en) | 1999-10-29 | 1999-10-29 | Method for reduction treatment of hexavalent chromium in heavy metal, waste liquid |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2001121162A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2678287C1 (en) * | 2017-10-30 | 2019-01-24 | Акционерное общество "Радиевый институт им. В.Г. Хлопина" | Method for decontamination of aqueous solutions containing compounds of hexavalent chrome |
| WO2019067972A1 (en) * | 2017-09-28 | 2019-04-04 | Hach Company | In-situ reduction of hexavalent chromium |
| CN111186940A (en) * | 2020-01-19 | 2020-05-22 | 西安瑞联新材料股份有限公司 | Industrial treatment method of high-valence chromium wastewater |
| CN113072142A (en) * | 2021-03-29 | 2021-07-06 | 温州大学 | Method for treating organic complex state chromium wastewater and synchronously controlling generation of hexavalent chromium |
-
1999
- 1999-10-29 JP JP30804999A patent/JP2001121162A/en not_active Withdrawn
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019067972A1 (en) * | 2017-09-28 | 2019-04-04 | Hach Company | In-situ reduction of hexavalent chromium |
| CN111051250A (en) * | 2017-09-28 | 2020-04-21 | 哈希公司 | In situ reduction and quenching of hexavalent chromium |
| RU2678287C1 (en) * | 2017-10-30 | 2019-01-24 | Акционерное общество "Радиевый институт им. В.Г. Хлопина" | Method for decontamination of aqueous solutions containing compounds of hexavalent chrome |
| CN111186940A (en) * | 2020-01-19 | 2020-05-22 | 西安瑞联新材料股份有限公司 | Industrial treatment method of high-valence chromium wastewater |
| CN113072142A (en) * | 2021-03-29 | 2021-07-06 | 温州大学 | Method for treating organic complex state chromium wastewater and synchronously controlling generation of hexavalent chromium |
| CN113072142B (en) * | 2021-03-29 | 2023-02-17 | 温州大学 | Method for treating organic complex state chromium wastewater and synchronously controlling generation of hexavalent chromium |
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