JP2017121604A - Treatment method of hexavalent chromium-containing waste liquid - Google Patents
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本発明は、６価クロム含有廃液の処理方法に関する。 The present invention relates to a method for treating hexavalent chromium-containing waste liquid.
ステンレス鋼の製造工程、クロメート処理など表面処理工程においては、６価クロムを含有する廃液（以下、「６価クロム含有廃液」という）が発生することがある。例えば、ステンレス鋼の製造工程においては、一般に、塩基度が高い環境下でステンレス鋼帯を加熱又は電解酸化する場合に、ステンレス鋼帯に含有されるクロムが６価クロムに酸化され、６価クロムが生成したステンレス鋼帯を水と接触させることにより、６価クロム含有廃液が発生する。６価クロムは有害な物質であるため、廃棄物処理するためには３価クロムに還元処理して無害化しなければならない。 In a surface treatment process such as a stainless steel manufacturing process and chromate treatment, a waste liquid containing hexavalent chromium (hereinafter referred to as “hexavalent chromium-containing waste liquid”) may be generated. For example, in the manufacturing process of stainless steel, in general, when a stainless steel strip is heated or electrolytically oxidized in an environment with a high basicity, chromium contained in the stainless steel strip is oxidized to hexavalent chromium. A hexavalent chromium-containing waste liquid is generated by bringing the stainless steel strip formed by the contact with water. Since hexavalent chromium is a harmful substance, it must be rendered harmless by reducing it to trivalent chromium in order to treat it as waste.
従来、６価クロム含有廃液の処理方法としては、６価クロム含有廃液に亜硫酸ナトリウム、硫酸第一鉄などを還元剤として加えて還元処理する方法が知られている（例えば、特許文献１及び２参照）。亜硫酸ナトリウムは、水に溶け易いために６価クロム含有廃液への添加が容易であり、生成する汚泥量も少ないという利点があるものの、高価であるという問題がある。また、硫酸第一鉄は、安価であり、酸性環境下及びアルカリ性環境下のいずれであっても還元処理ができるという利点があるものの、生成する汚泥量が多い（特に、水酸化鉄を含む汚泥が発生する）という問題がある。 Conventionally, as a method for treating a hexavalent chromium-containing waste liquid, a method is known in which sodium hexasulfite, ferrous sulfate, or the like is added to the hexavalent chromium-containing waste liquid as a reducing agent (for example, Patent Documents 1 and 2). reference). Although sodium sulfite is easily soluble in water, it can be easily added to a hexavalent chromium-containing waste liquid, and there is an advantage that the amount of sludge produced is small, but it is expensive. In addition, ferrous sulfate is inexpensive and has the advantage that it can be reduced in both acidic and alkaline environments, but it produces a large amount of sludge (especially sludge containing iron hydroxide). Occurs).
他方、石炭、重油などの化石燃料を燃焼させるボイラー施設においては、硫黄酸化物（例えば、二酸化硫黄）を含有する排ガスが発生する。この排ガスは、環境汚染の原因となるため、水酸化マグネシウムを用いた脱硫処理が行われている（例えば、特許文献３参照）。この脱硫処理で得られる脱硫廃液には、硫黄酸化物が水酸化マグネシウムと反応して生成した亜硫酸マグネシウムが含まれる。亜硫酸マグネシウムを含む脱硫廃液は、海などに放流すると、化学的酸素要求量（ＣＯＤ）を増大させてしまうため、無害な硫酸マグネシウムに酸化した後に放流されている。 On the other hand, in a boiler facility that burns fossil fuels such as coal and heavy oil, exhaust gas containing sulfur oxide (for example, sulfur dioxide) is generated. Since this exhaust gas causes environmental pollution, desulfurization treatment using magnesium hydroxide is performed (for example, see Patent Document 3). The desulfurization waste liquid obtained by this desulfurization treatment contains magnesium sulfite produced by the reaction of sulfur oxides with magnesium hydroxide. When the desulfurization waste liquid containing magnesium sulfite is discharged to the sea or the like, the chemical oxygen demand (COD) is increased. Therefore, the desulfurization waste liquid is discharged after being oxidized into harmless magnesium sulfate.
６価クロム含有廃液の従来の処理方法は、亜硫酸ナトリウム、硫酸第一鉄などの還元剤を購入して用いているため、６価クロム含有廃液の処理コストが増大するという問題があった。特に、高価な亜硫酸ナトリウムを還元剤として用いる場合、上記のように利点は多いものの、６価クロム含有廃液の処理コストが著しく増大してしまう。
他方、排ガスの脱硫処理で得られる脱硫廃液は、亜硫酸マグネシウムを硫酸マグネシウムに酸化するために大量の酸素を用いて長時間の曝気を行う必要があることから、その処理コストが増大するという問題があった。
The conventional treatment method of hexavalent chromium-containing waste liquid has a problem that the treatment cost of the hexavalent chromium-containing waste liquid increases because a reducing agent such as sodium sulfite and ferrous sulfate is purchased and used. In particular, when expensive sodium sulfite is used as a reducing agent, although there are many advantages as described above, the processing cost of the hexavalent chromium-containing waste liquid is remarkably increased.
On the other hand, the desulfurization waste liquid obtained by the desulfurization treatment of exhaust gas needs to be aerated for a long time using a large amount of oxygen in order to oxidize magnesium sulfite to magnesium sulfate. there were.
本発明は、上記のような問題を解決するためになされたものであり、生成する汚泥量が少なく、しかも処理コストを抑えることが可能な６価クロム含有廃液の処理方法を提供することを目的とする。 The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a method for treating a hexavalent chromium-containing waste liquid that produces a small amount of sludge and can reduce the treatment cost. And
本発明者らは、上記のような問題を解決すべく鋭意研究を続けた結果、硫黄酸化物を含有する排ガスを水酸化マグネシウムで脱硫処理して得られる脱硫廃液が、６価クロム含有廃液の処理に用いる還元剤として用いるのに適していることを見出し、本発明を完成するに至った。 As a result of continual research to solve the above problems, the present inventors have obtained a desulfurization waste liquid obtained by desulfurization treatment of exhaust gas containing sulfur oxides with magnesium hydroxide. It has been found that it is suitable for use as a reducing agent used in the treatment, and the present invention has been completed.
すなわち、本発明は、硫黄酸化物を含有する排ガスを水酸化マグネシウムで脱硫処理して脱硫廃液を得た後、前記脱硫廃液を還元剤として６価クロム含有廃液に加えて還元処理することを特徴とする６価クロム含有廃液の処理方法である。 That is, the present invention is characterized by desulfurizing exhaust gas containing sulfur oxide with magnesium hydroxide to obtain a desulfurization waste liquid, and then adding the desulfurization waste liquid as a reducing agent to the hexavalent chromium-containing waste liquid for reduction treatment. It is the processing method of hexavalent chromium containing waste liquid.
本発明によれば、還元処理で生成する汚泥量が少なく、しかも処理コストを抑えることが可能な６価クロム含有廃液の処理方法を提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the processing method of the hexavalent chromium containing waste liquid which can reduce the amount of sludge produced | generated by a reduction | restoration process and can suppress processing cost can be provided.
本発明の６価クロム含有廃液の処理方法は、硫黄酸化物を含有する排ガスを水酸化マグネシウムで脱硫処理して得られる脱硫廃液を、６価クロム含有廃液の処理に用いられる還元剤として用いることを特徴とする。 In the method for treating a hexavalent chromium-containing waste liquid according to the present invention, a desulfurization waste liquid obtained by desulfurizing exhaust gas containing sulfur oxides with magnesium hydroxide is used as a reducing agent used for treating the hexavalent chromium-containing waste liquid. It is characterized by.
本発明で用いられる脱硫廃液は、下記の化学反応式（１）に示すように、排ガスに含有される硫黄酸化物（例えば、ＳＯ２）と水酸化マグネシウム（Ｍｇ（ＯＨ）２）との反応によって生成した亜硫酸マグネシウム（ＭｇＳＯ３）を含む。
Ｍｇ（ＯＨ）２＋ＳＯ２→ＭｇＳＯ３＋Ｈ２Ｏ （１）
この脱硫廃液に含有される亜硫酸マグネシウムが、６価クロム含有廃液に含有される６価クロムを３価クロムに還元する還元剤として作用する。
The desulfurization waste liquid used in the present invention is a reaction of sulfur oxide (for example, SO 2 ) and magnesium hydroxide (Mg (OH) 2 ) contained in the exhaust gas as shown in the following chemical reaction formula (1). Containing magnesium sulfite (MgSO 3 ).
Mg (OH) 2 + SO 2 → MgSO 3 + H 2 O (1)
Magnesium sulfite contained in this desulfurization waste liquid acts as a reducing agent that reduces hexavalent chromium contained in the hexavalent chromium-containing waste liquid to trivalent chromium.
本発明で用いられる脱硫廃液は、従来、脱硫廃液に含有される亜硫酸マグネシウムを硫酸マグネシウムに酸化した後、海などに放流しており、大量の酸素を用いた長時間の曝気が要求される酸化処理に多大なコストがかかっていた。本発明では、この脱硫廃液を６価クロム含有廃液の還元処理における還元剤として有効活用しているため、脱硫廃液の廃棄量及び処理コストを削減することができる。 The desulfurization waste liquid used in the present invention has been conventionally oxidized to magnesium sulfate after oxidizing magnesium sulfite contained in the desulfurization waste liquid, and then released to the sea, etc., which is required for long-term aeration using a large amount of oxygen. Processing was very expensive. In the present invention, since this desulfurization waste liquid is effectively used as a reducing agent in the reduction treatment of the hexavalent chromium-containing waste liquid, the waste amount of the desulfurization waste liquid and the processing cost can be reduced.
また、従来の６価クロム含有廃液の処理方法は、還元剤を購入して用いていたため、６価クロム含有廃液の処理コストが増大していた。本発明では、これまで廃棄されていた脱硫廃液を６価クロム含有廃液の還元処理における還元剤として有効活用しているため、還元剤を購入する必要がなく、６価クロム含有廃液の処理コストを削減することができる。 Moreover, since the conventional processing method of the hexavalent chromium containing waste liquid has purchased and used the reducing agent, the processing cost of the hexavalent chromium containing waste liquid has increased. In the present invention, since the desulfurization waste liquid that has been disposed so far is effectively used as a reducing agent in the reduction treatment of the hexavalent chromium-containing waste liquid, it is not necessary to purchase a reducing agent, and the processing cost of the hexavalent chromium-containing waste liquid is reduced. Can be reduced.
本発明で用いられる脱硫廃液としては、硫黄酸化物を含有する排ガスを水酸化マグネシウムで脱硫処理して得られるものであれば特に限定されない。一般的には、脱硫廃液は、水酸化マグネシウム法（水マグ法）と呼ばれる排煙脱硫法によって得られる廃液である。 The desulfurization waste liquid used in the present invention is not particularly limited as long as it is obtained by desulfurizing exhaust gas containing sulfur oxide with magnesium hydroxide. Generally, the desulfurization waste liquid is a waste liquid obtained by a flue gas desulfurization method called a magnesium hydroxide method (water mug method).
硫黄酸化物を含有する排ガスとしては、特に限定されないが、一般に、ボイラー（例えば、一般産業用の小型又は中型ボイラー）、各種炉から排出された燃焼排ガスである。その中でも本発明に用いるのに適した排ガスは、ボイラーから排出された重質油の燃焼排ガスである。 Although it does not specifically limit as exhaust gas containing a sulfur oxide, Generally, it is the combustion exhaust gas discharged | emitted from the boiler (for example, small or medium-sized boiler for general industries) and various furnaces. Among them, exhaust gas suitable for use in the present invention is heavy oil combustion exhaust gas discharged from a boiler.
脱硫廃液に含有される亜硫酸マグネシウムの濃度は、特に限定されない。例えば、亜硫酸マグネシウムの濃度が低い場合、６価クロム含有廃液に対する脱硫廃液の添加量を増加すればよく、亜硫酸マグネシウムの濃度が高い場合、６価クロム含有廃液に対する脱硫廃液の添加量を減少すればよい。 The concentration of magnesium sulfite contained in the desulfurization waste liquid is not particularly limited. For example, when the concentration of magnesium sulfite is low, the addition amount of the desulfurization waste solution to the hexavalent chromium-containing waste solution may be increased. When the concentration of magnesium sulfite is high, the addition amount of the desulfurization waste solution to the hexavalent chromium-containing waste solution may be decreased. Good.
本発明によって処理される６価クロム含有廃液としては、特に限定されず、電子部品、機械部品、自動車用鋼板、ステンレス鋼などの製造工程時に発生する、６価クロムを含有する様々な工業排水を用いることができる。例えば、酸洗工程における塩浴槽、硫酸ソーダ電解槽、苛性ソーダ電解槽及びこれらの槽に後続して位置する洗浄槽などにおいて発生する廃液や、クロメート処理などの表面処理において発生する廃液などが挙げられる。 The waste liquid containing hexavalent chromium to be treated according to the present invention is not particularly limited, and various industrial wastewater containing hexavalent chromium generated during the manufacturing process of electronic parts, mechanical parts, automotive steel plates, stainless steel, and the like. Can be used. For example, waste liquid generated in a salt bath in a pickling process, a sodium sulfate electrolytic cell, a caustic soda electrolytic cell, a cleaning tank positioned subsequent to these tanks, a waste liquid generated in a surface treatment such as chromate treatment, etc. .
本発明の６価クロム含有廃液の処理方法は、還元剤として脱硫廃液を用いることを除き、従来の方法に準じて行うことができる。すなわち、６価クロム含有廃液にｐＨ調整剤（例えば、硫酸）を添加してｐＨを２〜３に調整した後、還元剤として脱硫廃液を添加することによって行われる。この処理によって生じる反応は、下記の化学反応式（２）に従う。
２Ｈ２ＣｒＯ４＋３ＭｇＳＯ３＋３Ｈ２ＳＯ４→Ｃｒ２（ＳＯ４）３＋３ＭｇＳＯ４＋５Ｈ２Ｏ （２）
上記の化学反応式（２）からわかるように、６価クロム含有廃液に含有される６価クロム（Ｈ２ＣｒＯ４）は、亜硫酸マグネシウム（ＭｇＳＯ３）を含有する脱硫廃液を用いた処理により、３価クロム（Ｃｒ２（ＳＯ４）３）に還元される。したがって、上記の反応を効率的に進めるためには、６価クロム含有廃液に含有される６価クロム（Ｈ２ＣｒＯ４）１モルに対して、脱硫廃液に含有される亜硫酸マグネシウム（ＭｇＳＯ３）を３モル程度となるように亜硫酸マグネシウムの濃度を制御することが好ましい。
The method for treating a hexavalent chromium-containing waste liquid of the present invention can be carried out in accordance with a conventional method except that a desulfurization waste liquid is used as a reducing agent. That is, it is performed by adding a pH adjuster (for example, sulfuric acid) to a hexavalent chromium-containing waste liquid to adjust the pH to 2-3, and then adding a desulfurization waste liquid as a reducing agent. The reaction caused by this treatment follows the chemical reaction formula (2) below.
2H 2 CrO 4 + 3MgSO 3 + 3H 2 SO 4 → Cr 2 (SO 4 ) 3 + 3MgSO 4 + 5H 2 O (2)
As can be seen from the above chemical reaction formula (2), hexavalent chromium (H 2 CrO 4 ) contained in the hexavalent chromium-containing waste liquid is treated with a desulfurization waste liquid containing magnesium sulfite (MgSO 3 ), It is reduced to trivalent chromium (Cr 2 (SO 4 ) 3 ). Therefore, in order to advance the above reaction efficiently, magnesium sulfite (MgSO 3 ) contained in the desulfurization waste liquid with respect to 1 mol of hexavalent chromium (H 2 CrO 4 ) contained in the hexavalent chromium-containing waste liquid. It is preferable to control the concentration of magnesium sulfite so as to be about 3 mol.
他方、硫酸第一鉄を還元剤として用いる６価クロム含有廃液の処理によって生じる反応は、下記の化学反応式（３）に従う。
２Ｈ２ＣｒＯ４＋６ＦｅＳＯ４＋６Ｈ２ＳＯ４→Ｃｒ２（ＳＯ４）３＋３Ｆｅ（ＳＯ４）３＋８Ｈ２Ｏ （３）
上記の化学反応式（２）及び（３）からわかるように、６価クロム含有廃液に含有される６価クロム（Ｈ２ＣｒＯ４）１モルを３価クロム（Ｃｒ２（ＳＯ４）３）に還元するためには、脱硫廃液を還元剤として用いる方法ではｐＨ調整剤（硫酸）が３／２モル必要であるのに対し、硫酸第一鉄を還元剤として用いる方法ではｐＨ調整剤（硫酸）が３モル必要である。したがって、脱硫廃液を還元剤として用いる本発明の６価クロム含有廃液の処理方法によれば、硫酸第一鉄を還元剤として用いる６価クロム含有廃液の処理方法に比べて、ｐＨ調整剤（硫酸）の量を低減することができる。
On the other hand, the reaction caused by the treatment of the hexavalent chromium-containing waste liquid using ferrous sulfate as a reducing agent follows the following chemical reaction formula (3).
2H 2 CrO 4 + 6FeSO 4 + 6H 2 SO 4 → Cr 2 (SO 4 ) 3 + 3Fe (SO 4 ) 3 + 8H 2 O (3)
As can be seen from the above chemical reaction formulas (2) and (3), 1 mol of hexavalent chromium (H 2 CrO 4 ) contained in the hexavalent chromium-containing waste liquid is converted to trivalent chromium (Cr 2 (SO 4 ) 3 ). In order to reduce it to 3%, the method using desulfurization waste liquid as a reducing agent requires 3/2 moles of pH adjusting agent (sulfuric acid), whereas the method using ferrous sulfate as the reducing agent requires pH adjusting agent (sulfuric acid). ) Is required 3 moles. Therefore, according to the processing method of the hexavalent chromium-containing waste liquid of the present invention using the desulfurization waste liquid as the reducing agent, compared with the processing method of the hexavalent chromium-containing waste liquid using ferrous sulfate as the reducing agent, the pH adjuster (sulfuric acid ) Amount can be reduced.
脱硫廃液を用いて処理された６価クロム含有廃液は、消石灰（Ｃａ（ＯＨ）２）などのアルカリ剤を添加し、ｐＨを６〜８に調整して中和した後、凝集剤をさらに添加して水酸化クロムとして沈降させ、シックナーによって固液分離される。この処理によって生じる反応は、下記の化学反応式（４）に従う。
Ｃｒ２（ＳＯ４）３＋３Ｃａ（ＯＨ）２→２Ｃｒ（ＯＨ）３＋３ＣａＳＯ４ （４）
The hexavalent chromium-containing waste liquid treated with the desulfurization waste liquid is added with an alkali agent such as slaked lime (Ca (OH) 2 ), neutralized by adjusting the pH to 6 to 8, and then further added with a flocculant Then, it is precipitated as chromium hydroxide and solid-liquid separated by a thickener. The reaction caused by this treatment follows the chemical reaction formula (4) below.
Cr 2 (SO 4 ) 3 + 3Ca (OH) 2 → 2Cr (OH) 3 + 3CaSO 4 (4)
他方、硫酸第一鉄を用いて処理した場合は、上記の化学反応式（４）によって生成する水酸化クロムだけでなく、下記の化学反応式（５）によって水酸化鉄も生成する。
Ｆｅ２（ＳＯ４）３＋３Ｃａ（ＯＨ）２→２Ｆｅ（ＯＨ）３＋３ＣａＳＯ４ （５）
したがって、化学反応式（４）及び（５）からわかるように、脱硫廃液を還元剤として用いる本発明の６価クロム含有廃液の処理方法によれば、硫酸第一鉄を還元剤として用いる６価クロム含有廃液の処理方法に比べて、汚泥量を少なくすることができる。
On the other hand, when the treatment is performed using ferrous sulfate, not only chromium hydroxide generated by the above chemical reaction formula (4) but also iron hydroxide is generated by the following chemical reaction formula (5).
Fe 2 (SO 4 ) 3 + 3Ca (OH) 2 → 2Fe (OH) 3 + 3CaSO 4 (5)
Therefore, as can be seen from the chemical reaction formulas (4) and (5), according to the method for treating a hexavalent chromium-containing waste liquid of the present invention using a desulfurization waste liquid as a reducing agent, hexavalent using ferrous sulfate as a reducing agent. The amount of sludge can be reduced compared to the method for treating chromium-containing waste liquid.
本発明の６価クロム含有廃液の処理方法は、６価クロム含有廃液の処理コストだけでなく、硫黄酸化物を含有する排ガスを水酸化マグネシウムで脱硫処理して得られる脱硫廃液の処理コストも低減することができる。また、本発明の６価クロム含有廃液の処理方法は、当該処理に用いるｐＨ調整剤（硫酸）の量を低減することができると共に、生成する汚泥量を少なくすることができる。 The treatment method of hexavalent chromium-containing waste liquid of the present invention reduces not only the treatment cost of hexavalent chromium-containing waste liquid but also the treatment cost of desulfurization waste liquid obtained by desulfurizing exhaust gas containing sulfur oxide with magnesium hydroxide. can do. Moreover, the processing method of the hexavalent chromium containing waste liquid of this invention can reduce the quantity of the sludge to produce | generate while being able to reduce the quantity of the pH adjuster (sulfuric acid) used for the said process.
以下、実施例によって本発明を更に説明するが、本発明はこれらの実施例によって限定されるものではない。 EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited by these Examples.
（実施例１）
ボイラーから排出されたＣ重油の燃焼排ガスを水酸化マグネシウムで脱硫処理して脱硫廃液を得た。この脱硫廃液中の亜硫酸マグネシウムの濃度は１９，４５７ｐｐｍであった。
また、６価クロム含有廃液として、ステンレス鋼の酸洗工程で発生した廃液を準備した。この６価クロム含有廃液中の６価クロム濃度は１００ｐｐｍであった。
次に、６価クロム含有廃液（液量０．５ｍＬ、６価クロム含有量５０ｍｇ）に硫酸を加えてｐＨを２．５に調整し、脱硫廃液（液量１５ｍＬ、亜硫酸マグネシウム含有量２９２ｍｇ）を加えて還元処理を行った。その後、消石灰２８６ｍｇを含む水溶液（液量２ｍＬ）をさらに加えてｐＨを８．５とし、凝集剤を数滴加えて汚泥（水酸化クロム）を沈降させた。汚泥を分離した後の水溶液をジフェニルカルバジド法によって６価クロムの有無を確認した結果、６価クロムが存在しないことを確認した。
Example 1
The C heavy oil combustion exhaust gas discharged from the boiler was desulfurized with magnesium hydroxide to obtain a desulfurization waste liquid. The concentration of magnesium sulfite in this desulfurization waste liquid was 19,457 ppm.
Moreover, the waste liquid which generate | occur | produced in the pickling process of stainless steel was prepared as hexavalent chromium containing waste liquid. The hexavalent chromium concentration in this hexavalent chromium-containing waste liquid was 100 ppm.
Next, sulfuric acid is added to the hexavalent chromium-containing waste liquid (liquid amount 0.5 mL, hexavalent chromium content 50 mg) to adjust the pH to 2.5, and the desulfurization waste liquid (liquid amount 15 mL, magnesium sulfite content 292 mg) In addition, reduction treatment was performed. Thereafter, an aqueous solution containing 286 mg of slaked lime (2 mL of liquid volume) was further added to adjust the pH to 8.5, and a few drops of flocculant were added to precipitate sludge (chromium hydroxide). As a result of confirming the presence or absence of hexavalent chromium in the aqueous solution after separating the sludge by the diphenylcarbazide method, it was confirmed that hexavalent chromium was not present.
（比較例１）
脱硫廃液の代わりに、硫酸第一鉄を含有する水溶液（液量３ｍＬ、硫酸第一鉄含有量７５０ｍｇ）を用いて還元処理を行った。その後、消石灰５３６ｍｇを含む水溶液（液量３．７５ｍＬ）をさらに加えてｐＨを８．５とし、凝集剤を数滴加えて汚泥（水酸化クロム及び水酸化鉄）を沈降させた。汚泥を分離した後の水溶液をジフェニルカルバジド法によって６価クロムの有無を確認した結果、６価クロムが存在しないことを確認した。
(Comparative Example 1)
Instead of the desulfurization waste liquid, reduction treatment was performed using an aqueous solution containing ferrous sulfate (liquid amount: 3 mL, ferrous sulfate content: 750 mg). Thereafter, an aqueous solution (liquid amount: 3.75 mL) containing 536 mg of slaked lime was further added to adjust the pH to 8.5, and a few drops of a flocculant were added to precipitate sludge (chromium hydroxide and iron hydroxide). As a result of confirming the presence or absence of hexavalent chromium in the aqueous solution after separating the sludge by the diphenylcarbazide method, it was confirmed that hexavalent chromium was not present.
以上の結果からわかるように、脱硫廃液を還元剤として用いた場合であっても硫酸第一鉄を用いた場合と同様に６価クロム含有廃液の還元処理ができた。また、脱硫廃液を還元剤として用いた場合、硫酸第一鉄を還元剤として用いた場合に比べて、消石灰の配合量を少なくすることができ、その結果として汚泥の生成量を少なくすることができた。 As can be seen from the above results, even when the desulfurization waste liquid was used as the reducing agent, the reduction treatment of the hexavalent chromium-containing waste liquid could be performed as in the case of using ferrous sulfate. Moreover, when desulfurization waste liquid is used as a reducing agent, the amount of slaked lime can be reduced compared with the case where ferrous sulfate is used as a reducing agent, and as a result, the amount of sludge produced can be reduced. did it.
したがって、本発明によれば、還元処理で生成する汚泥量が少なく、しかも処理コストを抑えることが可能な６価クロム含有廃液の処理方法を提供することができる。 Therefore, according to the present invention, it is possible to provide a method for treating a hexavalent chromium-containing waste liquid that can reduce the amount of sludge produced by the reduction treatment and can reduce the treatment cost.
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| JP2019026521A (en) * | 2017-08-01 | 2019-02-21 | 宇部興産株式会社 | Method for producing potassium chloride salt |
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| JPS63267494A (en) * | 1987-04-27 | 1988-11-04 | Nkk Corp | Treatment of waste liquid containing hexavalent chromium |
| US5158687A (en) * | 1991-07-11 | 1992-10-27 | Hydrite Chemical Co. | Methods of removing undesired ions from aqueous solutions |
| JP2007181756A (en) * | 2006-01-05 | 2007-07-19 | Japan Energy Corp | Wastewater treatment method for flue gas desulfurization equipment |
| JP2010201406A (en) * | 2009-03-04 | 2010-09-16 | Nippon Sozai Kogaku Kenkyusho:Kk | Hexavalent chromium reducing agent |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63267494A (en) * | 1987-04-27 | 1988-11-04 | Nkk Corp | Treatment of waste liquid containing hexavalent chromium |
| US5158687A (en) * | 1991-07-11 | 1992-10-27 | Hydrite Chemical Co. | Methods of removing undesired ions from aqueous solutions |
| JP2007181756A (en) * | 2006-01-05 | 2007-07-19 | Japan Energy Corp | Wastewater treatment method for flue gas desulfurization equipment |
| JP2010201406A (en) * | 2009-03-04 | 2010-09-16 | Nippon Sozai Kogaku Kenkyusho:Kk | Hexavalent chromium reducing agent |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2019026521A (en) * | 2017-08-01 | 2019-02-21 | 宇部興産株式会社 | Method for producing potassium chloride salt |
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