JP5985925B2 - Method and apparatus for treating waste liquid containing heavy metal - Google Patents
Method and apparatus for treating waste liquid containing heavy metal Download PDFInfo
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本発明は、重金属類および重金属類と錯体を形成する錯化剤を含有する重金属含有廃液の処理方法及び装置に関し、より詳細には、銅および銅と錯体を形成するアミン類を含有する廃液から、銅を分離・除去する方法及び装置に関する。 The present invention relates to a method and apparatus for treating heavy metal-containing waste liquids containing heavy metals and complexing agents that form complexes with heavy metals, and more particularly, from waste liquids containing copper and amines that form complexes with copper. The present invention relates to a method and apparatus for separating and removing copper.
銅等の重金属類を含む廃液から重金属類を除去する方法として、一般に重金属類がアルカリ性条件の下、不溶性の重金属の水酸化物を形成することを利用し、これを固液分離することで、重金属類を除去することが広く実施されている。
一方、重金属類を含有する廃液の中には、重金属と錯体を形成する錯化剤を含有する廃液がある。これらの廃液の例として、銅とモノエタノールアミンを含有する廃液が挙げられる。
As a method for removing heavy metals from waste liquids containing heavy metals such as copper, generally, heavy metals form an insoluble heavy metal hydroxide under alkaline conditions, and this is solid-liquid separated. It is widely practiced to remove heavy metals.
On the other hand, among waste liquids containing heavy metals, there is a waste liquid containing a complexing agent that forms a complex with heavy metals. Examples of these waste liquids include waste liquids containing copper and monoethanolamine.
このような錯化剤を含有する廃液は、重金属イオンが錯化剤と錯体を形成するため、アルカリ条件下でも重金属イオンは水酸化物を形成せず、廃液中で重金属イオン（錯イオン）の状態のまま溶存した状態で存在する。このため、錯化剤を含有する重金属類含有廃液は水酸化物沈殿法による重金属類の分離除去が困難である。 In waste liquids containing such complexing agents, heavy metal ions form complexes with complexing agents, so heavy metal ions do not form hydroxides even under alkaline conditions. It exists in a dissolved state. For this reason, it is difficult to separate and remove heavy metals by a hydroxide precipitation method from a waste liquid containing heavy metals containing a complexing agent.
このような錯化剤を含む重金属含有廃液処理方法の例として、例えば特許第１４５７６４６号（特許文献１）には、カルシウム化合物と鉄化合物を添加することで、銅を除去することが開示されている。この方式では銅錯体を含む廃液に鉄イオンを添加することで、錯体中の銅が鉄と置換され、銅イオンが遊離状態となる。さらにカルシウム化合物を添加することで、錯体中の鉄イオンがカルシウムイオンに置換され、アルカリ条件下で鉄と銅の水酸化物が沈殿することで廃液から銅を沈殿物の形態で分離・除去するものである。 As an example of the heavy metal-containing waste liquid treatment method including such a complexing agent, for example, Patent No. 1457646 (Patent Document 1) discloses that copper is removed by adding a calcium compound and an iron compound. Yes. In this method, by adding iron ions to the waste liquid containing the copper complex, the copper in the complex is replaced with iron, and the copper ions are in a free state. Furthermore, by adding a calcium compound, the iron ions in the complex are replaced with calcium ions, and the hydroxides of iron and copper are precipitated under alkaline conditions to separate and remove copper from the waste liquid in the form of precipitates. Is.
本発明者らは、ある銅含有錯体廃液の処理に特許文献１の方法を適用したところ、当該廃液に塩化鉄と水酸化カルシウムを添加した場合、廃液中の銅の約９５％程度を除去できることは確認した。しかし、なお処理水中に銅が６０ｍｇ／Ｌ程度残留しているため、放流先の条件によっては別途銅を除去する必要があった。また、廃液にカルシウム化合物を大量に添加すると、廃液に硫酸イオンが含まれる場合、不溶性の塩である硫酸カルシウム（石膏）が析出するという問題がある。また、アルカリ条件下では炭酸カルシウムが析出し、これらが反応槽や配管、撹拌機などに析出し、極端な場合には配管閉塞などの問題を引き起こすことがあった。 As a result of applying the method of Patent Document 1 to the treatment of a certain copper-containing complex waste liquid, the present inventors can remove about 95% of the copper in the waste liquid when iron chloride and calcium hydroxide are added to the waste liquid. Confirmed. However, since about 60 mg / L of copper remains in the treated water, it was necessary to remove copper separately depending on the conditions of the discharge destination. Further, when a large amount of calcium compound is added to the waste liquid, there is a problem that calcium sulfate (gypsum), which is an insoluble salt, is precipitated when the waste liquid contains sulfate ions. In addition, calcium carbonate precipitates under alkaline conditions, and these precipitate in reaction vessels, piping, agitators, etc., and in extreme cases, may cause problems such as piping clogging.
本発明は、上述の事情に鑑みなされたもので、錯化剤を含む重金属含有廃液から重金属類を分離・除去し、良好な水質の処理水を得る重金属含有廃液の処理方法及び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 circumstances, and provides a heavy metal-containing waste liquid treatment method and apparatus for separating and removing heavy metals from a heavy metal-containing waste liquid containing a complexing agent and obtaining treated water of good water quality. For the purpose.
上述の目的を達成するため、本発明の重金属含有廃液の処理方法は、重金属類および重金属類と錯体を形成する錯化剤を含有する廃液の処理方法であって、当該廃液に酸を添加しｐＨを６〜７の中性付近に調整し、廃液中の析出物を沈殿・分離した後、前記析出物を分離した後の上澄液としての廃液に鉄塩を添加し、鉄塩を添加した後に当該廃液に酸を添加して当該廃液のｐＨを２〜４に一旦下げた後に、アルカリ金属の水酸化物を添加し、ｐＨを１０以上のアルカリ条件に上昇させ、重金属類と鉄を含む固形物を沈殿させることにより、当該廃液より重金属類を分離・除去することを特徴とする。 In order to achieve the above object, the method for treating a heavy metal-containing waste liquid according to the present invention is a method for treating a waste liquid containing a heavy metal and a complexing agent that forms a complex with the heavy metal, wherein an acid is added to the waste liquid. Adjust pH to 6-7 neutral, precipitate and separate the precipitate in the waste liquid, then add iron salt to the waste liquid as the supernatant after separating the precipitate and add the iron salt After the acid is added to the waste liquid to lower the pH of the waste liquid to 2-4, alkali metal hydroxide is added, the pH is raised to 10 or more alkaline conditions, and heavy metals and iron are added. It is characterized by separating and removing heavy metals from the waste liquid by precipitating the contained solid matter.
本発明によれば、重金属類を含む廃液であり、重金属と錯体を形成する錯化剤が共存している廃液を処理することができる。重金属としては、銅、クロム、亜鉛、ニッケル、マンガンなどが挙げられる。廃液に含まれている錯化剤としては、モノエタノールアミン、トリエタノールアミンなどのアミン類が挙げられる。このような廃液の例として、アルカリ性で溶解性の銅を含む無電解めっき廃液が挙げられる。
廃液に添加するアルカリ金属の水酸化物として水酸化ナトリウムや水酸化カリウムが挙げられるが、入手性や価格などを考慮すると水酸化ナトリウム溶液の利用が適切である。
ADVANTAGE OF THE INVENTION According to this invention, it is a waste liquid containing heavy metals and the waste liquid in which the complexing agent which forms a complex with a heavy metal can coexist. Examples of heavy metals include copper, chromium, zinc, nickel, and manganese. Examples of the complexing agent contained in the waste liquid include amines such as monoethanolamine and triethanolamine. An example of such a waste liquid is an electroless plating waste liquid containing alkaline and soluble copper.
Examples of the alkali metal hydroxide to be added to the waste liquid include sodium hydroxide and potassium hydroxide, but considering the availability and price, it is appropriate to use a sodium hydroxide solution.
本発明の好ましい態様によれば、前記鉄塩は二価の鉄塩であることを特徴とする。
廃液に添加する鉄塩としては、溶液中で二価の鉄イオンとなる塩化鉄（II）（ＦｅＣｌ２）や硫酸鉄（II）（ＦｅＳＯ４）の使用が適切である。塩化鉄（III）のような三価の鉄塩も本発明の処理に使用することが可能であるが、三価の鉄塩では処理水に残留する重金属類濃度が、二価の鉄塩を使用した場合に比べて高くなることがあるため、要求される処理水質に応じて選定することが好ましい。
According to a preferred aspect of the present invention, the iron salt is a divalent iron salt.
As the iron salt to be added to the waste liquid, it is appropriate to use iron (II) chloride (FeCl 2 ) or iron (II) sulfate (FeSO 4 ) which becomes divalent iron ions in the solution. Trivalent iron salts such as iron (III) chloride can also be used in the treatment of the present invention. However, in the case of trivalent iron salts, the concentration of heavy metals remaining in the treated water is different from that of divalent iron salts. Since it may be higher than when used, it is preferable to select according to the required quality of the treated water.
本発明によれば、前記鉄塩を添加した後で前記アルカリ金属の水酸化物を添加する前に、当該廃液に酸を添加して当該廃液のｐＨを一旦下げた後に、前記アルカリ金属の水酸化物を添加してｐＨをアルカリ条件に上昇させる。
鉄塩を添加した後の廃液は一般にｐＨが低下するが、鉄塩を添加することに加え、酸を添加してｐＨをさらに下げることで処理水中の重金属類の濃度を低減できる。廃液の処理実験を行ったところ、廃液に鉄塩の一種である塩化鉄（II）を添加後、さらに酸を添加しｐＨ２〜４．５とした後にアルカリ金属の水酸化物を添加する処理を行うことで、処理水中の銅濃度を約０．９〜０．１ｍｇ／Ｌに低減することができるという効果が認められた（図３参照）。酸を添加しｐＨを調整することにより、錯体から重金属イオンを遊離しやすくすることができると考えられる。従って、あらかじめ小スケールでの試験を実施し、要求される処理水水質（銅の許容濃度）に応じて鉄塩添加後のｐＨ調整の際の適切なｐＨ値を決めておくことが好ましい。このように酸添加の効果が認められる廃液の場合には、処理設備には反応槽内のｐＨ測定設備を設け、鉄塩添加後の廃液のｐＨを所望のｐＨに維持できるように、反応槽に酸を添加する制御を行うことが望ましい。
According to the onset bright, prior to the addition of hydroxides of the alkali metals after the addition of the iron salt, after lowering once the pH of the waste solution by adding an acid to the waste solution, the alkali metal Hydroxide is added to raise the pH to alkaline conditions .
The waste liquid after adding the iron salt generally has a lowered pH, but in addition to adding the iron salt, the concentration of heavy metals in the treated water can be reduced by further reducing the pH by adding an acid. When a waste liquid treatment experiment was conducted, after adding iron (II) chloride, which is a kind of iron salt, to the waste liquid, an acid was added to adjust the pH to 2 to 4.5, and then an alkali metal hydroxide was added. By performing, the effect that the copper concentration in treated water could be reduced to about 0.9-0.1 mg / L was recognized (refer FIG. 3). It is thought that heavy metal ions can be easily released from the complex by adding an acid and adjusting the pH. Therefore, it is preferable to carry out a test on a small scale in advance and determine an appropriate pH value for pH adjustment after iron salt addition according to the required quality of treated water (permissible concentration of copper). In the case of a waste liquid in which the effect of acid addition is recognized in this way, the treatment facility is provided with a pH measurement facility in the reaction tank, so that the pH of the waste liquid after iron salt addition can be maintained at a desired pH. It is desirable to control the addition of acid to the liquid.
本発明によれば、前記廃液に前記鉄塩を添加する前に、当該廃液に酸を添加しｐＨを６以上の中性付近に調整し、廃液中の析出物を沈殿・分離した後、前記析出物を分離した後の上澄液としての廃液に前記鉄塩を添加する。
図４（定性分析化学ＩＩ，共立出版，１９７４年発行，３７６頁より引用）に示すように、銅の溶解性はｐＨ６以下になると急激に増加することが知られている。そのため、銅を水酸化物として沈殿させるためにはｐＨ６以上でアルカリ条件にすることが望ましい。
一方、重金属と錯体を形成するアミノ基を有する錯化剤（以下、単にアミン類と称す）は、水中では以下のような平衡状態にあると考えられる。
ＨＯ−Ｒ−ＮＨ２ ＋ Ｈ＋ ←→ ＨＯ−Ｒ−Ｎ＋Ｈ３
（Ｒ：炭化水素鎖）
錯化剤含有廃液のアルカリ度が強くなると、この反応の平衡は左に進み、廃液中でのＨＯ−Ｒ−ＮＨ２の形態の分子の割合が多くなると考えられる。一方、廃液が酸性になると廃液中に水素イオン（Ｈ＋）が増えるため、この平衡は右に進み、ＨＯ−Ｒ−Ｎ＋Ｈ３の割合が多くなると考えられる。
ここでアミン類と重金属である銅イオンとの錯体を考えると、アミン類が陽電荷をもたないＨＯ−Ｒ−ＮＨ２の形態では、銅イオンＣｕ２ ＋と安定した錯体を形成できるが、陽電荷をもつＨＯ−Ｒ−Ｎ＋Ｈ３の形態では、銅イオンの陽電荷とアミノ基の陽電荷が反発し、錯体が不安定になると考えられる。従って、銅−アミン錯体から銅イオンを遊離させ、分離・除去しやすくするためには廃液のｐＨを下げることが有効と考えられる。
このように、銅−アミン錯体からの銅イオン遊離のためにはｐＨが低い方が良いが、遊離した銅イオンが沈殿するためにはｐＨ６以上であることが望ましい。このため、処理対象の廃液の重金属類の濃度が高い場合には、鉄塩を添加する前に、塩酸などの酸を添加することにより、あらかじめ廃液のｐＨを６〜７の中性程度まで低下させ、廃液中の一部の重金属類を析出させたのち、これを分離・除去することにより、廃液中の重金属類がある程度除去されるため、次の処理で添加する鉄塩量を減らすことができる。
According to the onset bright, prior to adding the iron salt to the waste, after the addition of acid to the effluent pH was adjusted to about 6 or more neutral, precipitated and separated the precipitate in the effluent, The iron salt is added to a waste liquid as a supernatant after separating the precipitate .
As shown in FIG. 4 (Qualitative Analytical Chemistry II, Kyoritsu Shuppan, published in 1974, cited from page 376), it is known that the solubility of copper rapidly increases when the pH is 6 or less. Therefore, in order to precipitate copper as a hydroxide, it is desirable to use alkaline conditions at
On the other hand, a complexing agent having an amino group that forms a complex with a heavy metal (hereinafter simply referred to as amines) is considered to be in the following equilibrium state in water.
HO-R-NH 2 + H + ← → HO-R-N + H 3
(R: hydrocarbon chain)
When the alkalinity of the complexing agent-containing waste liquid becomes strong, the equilibrium of this reaction proceeds to the left, and it is considered that the proportion of molecules in the form of HO—R—NH 2 in the waste liquid increases. On the other hand, when the waste liquid becomes acidic, hydrogen ions (H + ) increase in the waste liquid. Therefore, this equilibrium proceeds to the right, and it is considered that the ratio of HO—R—N + H 3 increases.
Considering a complex of amines and heavy metal copper ions here, in the form of HO—R—NH 2 where the amines do not have a positive charge, a stable complex can be formed with the copper ion Cu 2 + . In the form of HO—R—N + H 3 having a positive charge, the positive charge of the copper ion and the positive charge of the amino group are repelled, and the complex is considered to be unstable. Therefore, it is considered effective to lower the pH of the waste liquid in order to liberate copper ions from the copper-amine complex and facilitate separation and removal.
Thus, the lower pH is better for releasing copper ions from the copper-amine complex, but it is desirable that the pH is 6 or more for free copper ions to precipitate. For this reason, when the concentration of heavy metals in the waste liquid to be treated is high, by adding an acid such as hydrochloric acid before adding the iron salt, the pH of the waste liquid is lowered to a neutral level of 6 to 7 in advance. After depositing some heavy metals in the waste liquid and separating / removing it, the heavy metals in the waste liquid are removed to some extent, so the amount of iron salt added in the next treatment can be reduced. it can.
本発明の重金属含有廃液の処理方法は、重金属類および重金属類と錯体を形成する錯化剤を含有する廃液の処理方法であって、当該廃液に酸を添加しｐＨを６〜７の中性付近に調整し、次に鉄塩を添加し、次に混合廃液のｐＨが２〜４になるように酸を添加し、次にアルカリ金属の水酸化物を添加し、ｐＨを１０以上のアルカリ条件に上昇させ、重金属類と鉄を含む固形物を沈殿させることにより、当該廃液より重金属類を分離・除去することを特徴とする。
処理対象の廃液の重金属類の濃度が高い場合には、鉄塩を添加する前に、塩酸などの酸を添加することにより、段落〔００１２〕に記載したように廃液のｐＨ値と銅の溶解度の関係及び廃液のｐＨ値と銅−アミン錯体からの銅イオンの遊離しやすさの関係からあらかじめ廃液のｐＨを６〜７の中性付近まで低下させ、廃液中の一部の重金属類を析出させる。その後鉄塩を添加すると廃液のｐＨが低下するが、鉄塩を添加することに加え、ｐＨが２〜４になるように酸を添加することにより段落〔００１１〕に記載したように錯体から重金属イオンを遊離させその後水酸化物として析出させるため処理水中の銅濃度を低減することが可能である。
The method for treating a heavy metal-containing waste liquid according to the present invention is a method for treating a waste liquid containing heavy metals and a complexing agent that forms a complex with heavy metals, and an acid is added to the waste liquid to adjust the pH to 6 to 7 neutral. Next, an iron salt is added, then an acid is added so that the pH of the mixed waste liquid becomes 2 to 4, then an alkali metal hydroxide is added, and the pH is adjusted to 10 or more. It is characterized by separating and removing heavy metals from the waste liquid by increasing the conditions and precipitating solids containing heavy metals and iron.
If the concentration of heavy metals in the waste liquid to be treated is high, by adding an acid such as hydrochloric acid before adding the iron salt, the pH value of the waste liquid and the solubility of copper as described in paragraph [0012] From the relationship between the pH of the waste liquid and the relationship between the pH value of the waste liquid and the ease of liberation of copper ions from the copper-amine complex, the pH of the waste liquid is lowered to about 6 to 7 in advance to precipitate some heavy metals in the waste liquid. Let Thereafter, the iron salt is added to lower the pH of the waste solution. In addition to adding the iron salt, the acid is added so that the pH is 2 to 4, whereby the complex is changed from a heavy metal to a heavy metal as described in paragraph [0011]. It is possible to reduce the copper concentration in the treated water because ions are released and then precipitated as hydroxide.
本発明の重金属含有廃液の処理装置は、重金属類および重金属類と錯体を形成する錯化剤を含有する廃液の処理装置であって、廃液を収容する反応槽と、鉄塩を供給する配管と、酸を供給する配管と、アルカリ金属の水酸化物を供給する配管と、固液分離装置とを備え、前記反応槽において廃液に酸を添加しｐＨを６〜７の中性付近に調整し、当該廃液に鉄塩を添加した後、混合廃液のｐＨが２〜４になるように酸を添加し、アルカリ金属の水酸化物を添加し、ｐＨを１０以上のアルカリ条件に上昇させ、前記廃液から重金属類と鉄を含む固形物を沈殿させ、前記固液分離装置において前記廃液より重金属類を分離・除去することを特徴とする。 The heavy metal-containing waste liquid treatment apparatus of the present invention is a waste liquid treatment apparatus containing a heavy metal and a complexing agent that forms a complex with heavy metals, a reaction tank containing the waste liquid, a pipe for supplying iron salt, A pipe for supplying an acid, a pipe for supplying an alkali metal hydroxide, and a solid-liquid separator, and adjusting the pH to about 6 to 7 by adding acid to the waste liquid in the reaction vessel. Then, after adding an iron salt to the waste liquid, an acid is added so that the pH of the mixed waste liquid becomes 2 to 4, an alkali metal hydroxide is added, the pH is increased to 10 or more alkaline conditions, A solid substance containing heavy metals and iron is precipitated from the waste liquid, and the heavy metals are separated and removed from the waste liquid in the solid-liquid separator.
本発明の処理装置によれば、前記反応槽において廃液に前記鉄塩を添加する前に、当該廃液に酸を添加しｐＨを６以上の中性付近に調整する。
処理対象の廃液の重金属類の濃度が高い場合には、段落〔００１２〕に記載したように鉄塩を添加する前に、塩酸などの酸を添加することにより、あらかじめ廃液のｐＨを６〜７の中性付近まで低下させ、ある程度の重金属類を析出させるため、次の処理で添加する鉄塩量を減らすことができる。
According to the process equipment of the present invention, the prior addition of the iron salt to the waste liquid in the reaction vessel, adding an acid to the waste solution is adjusted to 6 or more in the vicinity of neutral pH.
When the concentration of heavy metals in the waste liquid to be treated is high, the pH of the waste liquid is adjusted to 6 to 7 in advance by adding an acid such as hydrochloric acid before adding the iron salt as described in paragraph [0012]. The amount of iron salt to be added in the next treatment can be reduced because a certain amount of heavy metals are precipitated to near neutrality.
本発明の重金属含有廃液の処理装置は、重金属類および重金属類と錯体を形成する錯化剤を含有する廃液の処理装置であって、廃液を収容する第一の反応槽と、酸を供給する配管と、ｐＨ測定手段と、廃液のｐＨに応じて酸の供給量を制御する制御装置と、第一の固液分離装置とを備え、廃液を収容する第二の反応槽と、鉄塩を供給する配管と、アルカリ金属の水酸化物を供給する配管と、第二の固液分離装置とをさらに備え、前記第一の反応槽において廃液に酸を添加しｐＨを６〜７の中性付近に調整し、廃液中の析出物を前記第一の固液分離装置で分離した後、前記析出物を分離した後の上澄液としての廃液を前記第二の反応槽に移送し、前記第二の反応槽において前記廃液に鉄塩を添加した後、酸を添加して廃液のｐＨを２〜４に下げた後にアルカリ金属の水酸化物を添加し、ｐＨを１０以上のアルカリ条件に上昇させ、前記廃液から重金属類と鉄を含む固形物を沈殿させ、前記第二の固液分離装置により前記廃液より重金属類を分離・除去することを特徴とする。 The heavy metal-containing waste liquid treatment apparatus of the present invention is a waste liquid treatment apparatus containing a heavy metal and a complexing agent that forms a complex with the heavy metal, a first reaction tank containing the waste liquid, and supplying an acid. A pipe, a pH measuring means, a control device for controlling the amount of acid supplied according to the pH of the waste liquid, a first solid-liquid separation device, a second reaction tank for containing the waste liquid, and an iron salt A pipe for supplying, a pipe for supplying an alkali metal hydroxide, and a second solid-liquid separator are further provided, and an acid is added to the waste liquid in the first reaction tank to adjust the pH to 6 to 7 neutral. After adjusting the precipitate in the waste liquid with the first solid-liquid separator, the waste liquid as a supernatant after separating the precipitate is transferred to the second reaction tank, after the addition of the iron salt to the waste liquid in the second reaction vessel, lowered by adding an acid and the pH of the effluent to 2-4 After the addition of alkali metal hydroxide to raise the pH to 10 or more alkaline conditions, the solid containing heavy metals and iron is precipitated from the waste, heavy metals from the waste liquid by the second solid-liquid separator It is characterized by separating and removing the species.
本発明は以下に列挙する効果を奏する。
（１）重金属類および重金属類と錯体を形成する錯化剤を含有する廃液に塩化鉄とアルカリ金属の水酸化物を添加することで、重金属類を分離・除去し、良好な水質の処理水を得ることができる。また、液体キレート剤を使用する場合に発生する可能性のある有害ガスの発生を抑えることができる。
（２）重金属類を含む廃液の一般的な処理方法である水酸化物沈殿法の適用が困難である重金属類と錯化剤とを含有する廃液を処理することができる。本発明では、錯化剤と錯体を形成した重金属を、鉄イオンとアルカリ金属イオンで置換することで、重金属類を沈殿しやすい状態に変化させることにより、重金属類を分離・除去できる。
（３）不溶性の塩を形成しにくいアルカリ金属の水酸化物を添加することで、汚泥発生量を抑制しながらアルカリ条件を達成して、重金属と鉄とを固形物として沈殿させることが可能となる。また、配管閉塞などの問題を回避することができる。
The present invention has the following effects.
(1) Heavy metal is separated and removed by adding iron chloride and alkali metal hydroxide to the waste liquid containing heavy metals and complexing agents that form complexes with heavy metals, and treated water with good water quality Can be obtained. Moreover, generation | occurrence | production of the harmful gas which may be generated when using a liquid chelating agent can be suppressed.
(2) It is possible to treat a waste liquid containing heavy metals and a complexing agent, which is difficult to apply a hydroxide precipitation method, which is a general treatment method for waste liquids containing heavy metals. In the present invention, heavy metals can be separated and removed by replacing heavy metals formed with a complexing agent with iron ions and alkali metal ions to change the heavy metals into a state in which they are easily precipitated.
(3) By adding an alkali metal hydroxide that hardly forms an insoluble salt, it is possible to achieve alkaline conditions while suppressing sludge generation, and to precipitate heavy metals and iron as solids. Become. Moreover, problems such as piping blockage can be avoided.
本発明の処理対象となる廃液は、重金属類を含む廃液であり、さらに重金属と錯体を形成する錯化剤が共存している廃液である。処理対象となる重金属としては、銅、クロム、亜鉛、ニッケル、マンガンなどが挙げられる。廃液に含まれている錯化剤としては、モノエタノールアミン、トリエタノールアミンなどのアミン類が挙げられる。このような廃液の具体例として、アルカリ性で溶解性の銅を含む無電解めっき廃液が挙げられる。 The waste liquid to be treated in the present invention is a waste liquid containing heavy metals, and is a waste liquid in which a complexing agent that forms a complex with heavy metals coexists. Examples of the heavy metal to be treated include copper, chromium, zinc, nickel, and manganese. Examples of the complexing agent contained in the waste liquid include amines such as monoethanolamine and triethanolamine. A specific example of such a waste liquid is an electroless plating waste liquid containing alkaline and soluble copper.
本発明による処理方法においては、まず最初に当該廃液に鉄塩を添加する。処理対象の廃液に添加する鉄塩としては、溶液中で二価の鉄イオンとなる塩化鉄（II）（ＦｅＣｌ２）や硫酸鉄（II）（ＦｅＳＯ４）の使用が適切である。なお、塩化鉄（III）のような三価の鉄塩も本発明の処理に使用することが可能である。しかし、三価の鉄塩では処理水に残留する重金属類濃度が、二価の鉄塩を使用した場合に比べて高くなることがあるため、要求される処理水質に応じて選定することが好ましい。
鉄塩の添加量は、処理対象廃液中の重金属類に対してモル比で決めることができる。図５に、銅含有廃液に塩化鉄（II）を添加し処理した場合の鉄の添加量と処理水銅濃度の関係の一例をグラフで示す。図５に示すように、鉄濃度が高くなるほど処理水銅濃度が低くなる傾向が認められ、廃液中の銅に対し鉄量をモル比で８．７倍量以上とすると処理水銅濃度が１ｍｇ／Ｌ以下となった。従って、鉄塩の添加量はあらかじめ小スケールでの試験を行うことにより、要求される処理水水質に応じて適切な鉄塩の添加量を決めておくことが好ましい。
In the treatment method according to the present invention, first, an iron salt is added to the waste liquid. As the iron salt added to the waste liquid to be treated, it is appropriate to use iron (II) chloride (FeCl 2 ) or iron (II) sulfate (FeSO 4 ) which becomes divalent iron ions in the solution. Trivalent iron salts such as iron (III) chloride can also be used for the treatment of the present invention. However, since the concentration of heavy metals remaining in the treated water in the trivalent iron salt may be higher than in the case of using the divalent iron salt, it is preferable to select according to the required treated water quality. .
The amount of iron salt added can be determined by the molar ratio with respect to the heavy metals in the waste liquid to be treated. FIG. 5 is a graph showing an example of the relationship between the amount of iron added and the concentration of treated water copper when iron (II) chloride is added to the copper-containing waste liquid for treatment. As shown in FIG. 5, as the iron concentration increases, the concentration of treated water copper tends to decrease. When the amount of iron is 8.7 times the molar ratio of copper in the waste liquid, the treated water copper concentration is 1 mg. / L or less. Therefore, it is preferable that the iron salt addition amount is determined in advance according to the required quality of the treated water by conducting a small-scale test.
鉄塩を添加した後の廃液は一般にｐＨが低下するが、本発明者らの試験によれば鉄塩を添加することに加え、酸を添加してｐＨをさらに下げることで処理水中の重金属類の濃度を低減できる場合があった。このため、あらかじめ小スケールでの処理試験を実施し、酸添加の効果を検討し、必要な処理水質に応じて適切なｐＨを決定しておくことが好ましい。
また、酸添加の効果が認められる廃液の場合には、処理設備には反応槽内のｐＨ測定設備を設け、鉄塩添加後の廃液のｐＨを所望のｐＨに維持できるように、反応槽に酸を添加する制御を行うことが望ましい。
Although the pH of the waste liquid after adding the iron salt generally decreases, according to the tests of the present inventors, in addition to adding the iron salt, by adding an acid to further lower the pH, heavy metals in the treated water In some cases, the concentration of can be reduced. For this reason, it is preferable to carry out a treatment test on a small scale in advance, examine the effect of acid addition, and determine an appropriate pH according to the required quality of the treated water.
In addition, in the case of waste liquid in which the effect of acid addition is recognized, the treatment facility is equipped with a pH measurement facility in the reaction tank, and the reaction tank is provided with a pH value so that the pH of the waste liquid after addition of the iron salt can be maintained at a desired pH. It is desirable to control the addition of acid.
次に、ｐＨ調整後の廃液に、アルカリ金属の水酸化物を添加する。廃液に添加するアルカリ金属の水酸化物として水酸化ナトリウムや水酸化カリウムが挙げられるが、入手性や価格などを考慮すると水酸化ナトリウム溶液の利用が適切である。
溶液中ではナトリウムイオンはカルシウムイオンと比較して不溶性の塩を形成しにくいため、操作や維持管理の面で水酸化ナトリウムの利用は水酸化カルシウムより有利である。
Next, an alkali metal hydroxide is added to the waste liquid after pH adjustment. Examples of the alkali metal hydroxide to be added to the waste liquid include sodium hydroxide and potassium hydroxide, but considering the availability and price, it is appropriate to use a sodium hydroxide solution.
In a solution, sodium ions are less likely to form insoluble salts than calcium ions, and therefore sodium hydroxide is more advantageous than calcium hydroxide in terms of operation and maintenance.
当該廃液にアルカリ金属の水酸化物を添加し、ｐＨをアルカリ条件下に調整すると、析出物が生成する。この析出物には水酸化鉄（II）を含むと考えられる汚泥と共に重金属類の水酸化物が含まれる。ここで二価の鉄イオンはｐＨ１０以上で溶解度が低下することが知られており、ｐＨを１０以上になるようにアルカリ剤を注入する制御を行うことが望ましい。
本発明による各薬品類の添加量は、あらかじめ小スケールでの処理試験を実施し、重金属類濃度が目標水質を満たすように注入率を決めるとよい。また、各薬品は固体・液体のいずれでも注入可能であるが、操作がしやすいことから溶液での注入が適切である。
When an alkali metal hydroxide is added to the waste liquid and the pH is adjusted under alkaline conditions, precipitates are generated. This deposit contains heavy metal hydroxides together with sludge that is thought to contain iron (II) hydroxide. Here, it is known that the solubility of divalent iron ions is lowered at a pH of 10 or more, and it is desirable to control the injection of an alkaline agent so that the pH is 10 or more.
The amount of each chemical added according to the present invention may be determined by carrying out a treatment test on a small scale in advance and determining the injection rate so that the heavy metal concentration satisfies the target water quality. Each chemical can be injected as either a solid or a liquid, but since it is easy to operate, injection with a solution is appropriate.
当該廃液に析出した生成物には水酸化鉄（II）や重金属類の水酸化物が含まれており、これらを固液分離することで、廃液から重金属類を分離・除去することができる。分離方法としては、沈降分離、凝集沈殿、ろ過などの一般的な固液分離方法を適用することができるが、固液分離方法の選定は析出物の性状に応じて適切な方法を選択することが好ましい。 The product precipitated in the waste liquid contains iron (II) hydroxide and heavy metal hydroxides, and heavy metals can be separated and removed from the waste liquid by solid-liquid separation. As a separation method, general solid-liquid separation methods such as sedimentation separation, coagulation sedimentation, and filtration can be applied, but the selection of the solid-liquid separation method should be selected according to the properties of the precipitate. Is preferred.
本処理方法では、重金属類は除去できるものの錯化剤はそのまま廃液中に残留するため、重金属を除去した後の廃液は、必要に応じて生物処理などの後処理を併用することで錯化剤を除去することが望ましい。また、本処理方法の後で重金属類がわずかに残留する場合の対策として、後段にキレート樹脂吸着設備や液体キレート剤の添加設備を併設することによって廃液に残留するわずかな重金属を除去することも可能である。
また、重金属除去後の廃液中の錯化剤は、重金属類が混入すると再び重金属錯体を形成し、除去しにくい錯イオン状態で重金属類が残留することになるので、重金属類を含む廃液と混合しないような処理方式を選択すべきである。
In this treatment method, although the heavy metals can be removed, the complexing agent remains in the waste liquid as it is, so the waste liquid after removing the heavy metal can be combined with a post-treatment such as biological treatment if necessary. It is desirable to remove. In addition, as a countermeasure when heavy metals remain slightly after this treatment method, it is also possible to remove the slight heavy metal remaining in the waste liquid by installing a chelate resin adsorption facility and a liquid chelating agent addition facility in the subsequent stage. Is possible.
In addition, the complexing agent in the waste liquid after removal of heavy metals will form heavy metal complexes again when heavy metals are mixed in, and heavy metals will remain in a complex ion state that is difficult to remove, so mix with waste liquids containing heavy metals. You should select a processing method that does not.
本処理法の適用に当たり、処理対象の廃液の重金属類の濃度が高い場合、添加する鉄塩量も増加する。この対策の一例として、鉄塩を添加する前に廃液のｐＨを６〜７の中性付近まで低下させることが挙げられる。この方法は、塩酸などの酸を添加することにより、あらかじめ廃液のｐＨを６〜７の中性付近まで低下させ、重金属類の一部を析出させたのち、これを分離・除去する。この方法により、廃液中の重金属類がある程度除去されるため、次の処理で添加する鉄塩量を減らすことができる。 In application of this treatment method, when the concentration of heavy metals in the waste liquid to be treated is high, the amount of iron salt to be added also increases. An example of this measure is to reduce the pH of the waste liquid to about 6 to 7 neutrality before adding the iron salt. In this method, by adding an acid such as hydrochloric acid, the pH of the waste liquid is lowered to about 6 to 7 neutral in advance, and a part of heavy metals is precipitated, and then separated and removed. By this method, heavy metals in the waste liquid are removed to some extent, so that the amount of iron salt added in the next treatment can be reduced.
この方法が適用できる廃液の一例としてアミン類を含む銅廃液が挙げられる。錯化剤がアミン類の場合、ｐＨを低下させることで錯化剤中のアミノ基に水素イオンが配位しプラスの荷電状態となるため、配位したプラスの電荷をもつ重金属イオンは遊離しやすくなる。
一方、重金属の一種である銅イオンの溶解度はｐＨが６未満となると急激に増加することが知られている。このため、廃液のｐＨを６〜７の中性付近に調整することで銅−アミン錯体からの銅イオンをある程度遊離させつつ、遊離した銅を水酸化物として析出させ、分離・除去することが可能となる。
このように重金属類の溶解度とアミン類の性質を利用し、適切なｐＨに調整することで廃液中の重金属類濃度を低減することが可能となり、鉄塩の添加量も低減できる。
An example of a waste liquid to which this method can be applied is a copper waste liquid containing amines. When the complexing agent is an amine, the hydrogen ion is coordinated to the amino group in the complexing agent by reducing the pH, resulting in a positive charge state. Therefore, the heavy metal ion having the coordinated positive charge is released. It becomes easy.
On the other hand, it is known that the solubility of copper ions, which are a kind of heavy metal, rapidly increases when the pH is less than 6. For this reason, by adjusting the pH of the waste liquid to about 6 to 7 neutrality, copper ions from the copper-amine complex are liberated to some extent, and the liberated copper is precipitated as hydroxide and separated and removed. It becomes possible.
Thus, by using the solubility of heavy metals and the properties of amines and adjusting to an appropriate pH, the concentration of heavy metals in the waste liquid can be reduced, and the amount of iron salt added can also be reduced.
処理対象の廃液の重金属類の濃度が高い場合の別な処理方法として、廃液に酸を添加しｐＨを低下させ、ある程度の重金属類を析出させておき、その後、鉄塩およびアルカリ金属類の水酸化物を添加する方法がある。この方法では、上述の方法と比較して、生成したスラリーの分離・除去操作を１回に減らすことが可能である。 As another treatment method when the concentration of heavy metals in the waste liquid to be treated is high, acid is added to the waste liquid to lower the pH, and a certain amount of heavy metals are precipitated, and then iron salt and alkaline metal water There is a method of adding an oxide. In this method, the separation / removal operation of the generated slurry can be reduced to one time as compared with the above-described method.
本発明の処理方法を実施するための廃液の処理装置（以下、「本発明の処理装置」という）としては、鉄塩を供給する配管、酸を供給する配管、アルカリ金属の水酸化物を供給する配管、ｐＨ測定手段、廃液のｐＨに応じて酸及びアルカリ金属の水酸化物の供給量を制御する制御装置を備えた処理装置が挙げられる。 As a waste liquid treatment apparatus for carrying out the treatment method of the present invention (hereinafter referred to as “treatment apparatus of the present invention”), a pipe for supplying an iron salt, a pipe for supplying an acid, and an alkali metal hydroxide are supplied. And a processing device provided with a control device for controlling the supply amount of acid and alkali metal hydroxide according to the pH of the waste liquid, the pH measurement means, and the waste liquid.
本発明の処理装置の一態様を図１に模式的に示す。本発明の処理対象となる重金属含有廃液は、重金属類を含む廃液であり、さらに重金属と錯体を形成する錯化剤が共存している廃液である。図１に示すように、本発明の処理装置は、重金属含有廃液１０を収容する反応槽１と、反応槽１内の重金属含有廃液１０に鉄塩を供給する配管１１と、酸を供給する配管１２と、アルカリ金属の水酸化物を供給する配管１３とを備えている。本発明の処理装置は、さらにｐＨ測定手段（図示省略）と、廃液のｐＨに応じて酸及びアルカリ金属の水酸化物の供給量を制御する制御装置（図示省略）とを備えている。
One embodiment of the processing apparatus of the present invention is schematically shown in FIG. The heavy metal-containing waste liquid to be treated according to the present invention is a waste liquid containing heavy metals, and is a waste liquid in which a complexing agent that forms a complex with heavy metals coexists. As shown in FIG. 1, the processing apparatus of this invention is the reaction tank 1 which accommodates the heavy metal containing
図１に示す本発明の処理装置では、反応槽１内の重金属含有廃液１０に配管１１を通して鉄塩が添加される。鉄塩が添加された後、配管１２を通して酸が添加され、廃液のｐＨが調整される。次に配管１３を通してアルカリ金属の水酸化物が反応槽１に供給される。反応槽１内で処理された廃液１０は固液分離装置２に移送され、固液分離装置２において固液分離され、処理水１４と重金属を含むスラリー１５とに分離される。
In the treatment apparatus of the present invention shown in FIG. 1, iron salt is added to the heavy metal-containing
また、本発明の処理方法を実施するための別の処理装置としては、図１に示す処理装置に廃液のｐＨを予め下げる反応槽を加えた処理装置が挙げられる。すなわち、本発明の処理装置は、ｐＨ測定手段、酸を供給する配管、ｐＨに応じて酸の供給量を調整する機能を持つ制御装置、廃液を貯留・撹拌する第一の反応槽を備えている。本発明の処理装置は、鉄塩を供給する配管、酸を供給する配管、アルカリ金属の水酸化物を供給する配管、ｐＨに応じて酸又はアルカリ金属の水酸化物の供給量を調整する機能を持つ制御装置、第二の反応槽を備えている。 Moreover, as another processing apparatus for implementing the processing method of this invention, the processing apparatus which added the reaction tank which lowers the pH of a waste liquid previously to the processing apparatus shown in FIG. 1 is mentioned. That is, the treatment apparatus of the present invention includes a pH measuring means, a pipe for supplying an acid, a control device having a function of adjusting an acid supply amount according to pH, and a first reaction tank for storing and stirring waste liquid. Yes. The treatment apparatus of the present invention is a pipe for supplying an iron salt, a pipe for supplying an acid, a pipe for supplying an alkali metal hydroxide, and a function of adjusting the supply amount of an acid or an alkali metal hydroxide according to pH. A control device having a second reaction tank.
本発明の処理装置の別の一態様を図２に模式的に示す。図２に示す態様においては、第一の反応槽２１内に重金属含有廃液１０が移送され、廃液１０に配管２２を通して酸を添加することにより廃液のｐＨを６〜７に下げるように調整し、廃液１０は第一の反応槽２１内で貯留・攪拌される。第一の反応槽２１内で処理された廃液１０は固液分離装置２３に移送されて、固液分離装置２３において固液分離され、スラリー２５が分離除去される。その後、廃液１０は第二の反応槽３１に移送される。第二の反応槽３１内の重金属含有廃液１０に配管３２を通して鉄塩が添加される。鉄塩が添加された後、配管３３を通して酸が添加され、廃液のｐＨが調整される。次に配管３４を通してアルカリ金属の水酸化物が第二の反応槽３１に供給される。第二の反応槽３１内で処理された廃液１０は固液分離装置３５に移送されて、固液分離装置３５において固液分離され、処理水３６と重金属を含むスラリー３７とに分離される。
Another embodiment of the processing apparatus of the present invention is schematically shown in FIG. In the embodiment shown in FIG. 2, the heavy metal-containing
次に実施例を挙げ、本発明をさらに詳しく説明するが、本発明はこれらの実施例に限定されるものではない。
実施例１
実施例１では、重金属として銅、錯化剤としてモノエタノールアミンを含む廃液を処理した。廃液の性状は、ｐＨが６．５、銅濃度が３５５ｍｇ／Ｌ、ＣＯＤＣｒ（二クロム酸カリウムによる化学的酸素要求量）が７７，４００ｍｇ／Ｌであった。
当該廃液の処理操作は、当該廃液に塩化鉄（II）を、廃液中の銅に対し、鉄のモル比が約１１倍量となるように添加した。その後、塩酸を添加しｐＨを２〜３程度に低下させ、５分以上放置した。次に、当該廃液に水酸化ナトリウムを添加しｐＨ１０に調整した。ｐＨ調整後、凝集沈殿により析出したスラリーを分離・除去し、処理水を得た。処理水を水質分析したところ、銅濃度は０．２ｍｇ／Ｌであった。また、汚泥発生量は約５７００ｍｇ／Ｌであった。
EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these Examples.
Example 1
In Example 1, a waste liquid containing copper as a heavy metal and monoethanolamine as a complexing agent was treated. The properties of the waste liquid were pH 6.5, copper concentration 355 mg / L, CODCr (chemical oxygen demand by potassium dichromate) 77,400 mg / L.
In the waste liquid treatment operation, iron (II) chloride was added to the waste liquid so that the molar ratio of iron was about 11 times the copper in the waste liquid. Thereafter, hydrochloric acid was added to lower the pH to about 2 to 3, and left for 5 minutes or longer. Next, sodium hydroxide was added to the waste liquid to adjust the pH to 10. After adjusting the pH, the slurry deposited by coagulation precipitation was separated and removed to obtain treated water. When the water quality of the treated water was analyzed, the copper concentration was 0.2 mg / L. Moreover, the amount of sludge generation was about 5700 mg / L.
比較例１
比較例１では、重金属として銅、錯化剤としてモノエタノールアミンを含む廃液を処理した。廃液の性状はｐＨが６．５、銅濃度が２２０ｍｇ／Ｌ、ＣＯＤＣｒが５０，２００ｍｇ／Ｌであった。比較例１での処理廃液は、成分は実施例１と同じであるが、銅濃度及びＣＯＤＣｒの濃度がやや低い性状であった。
比較例１では当該廃液に塩化鉄（II）を廃液中の銅に対し、鉄のモル比が約１２倍量となるように添加した。その後、塩酸を添加しｐＨを２〜３程度に低下させ、５分以上放置した。次に、当該廃液に水酸化カルシウムを添加し、ｐＨ１０に調整した。ｐＨ調整後、凝集沈殿により析出したスラリーを分離・除去し、処理水を得た。処理水を分析したところ、銅濃度は０．５ｍｇ／Ｌであり、実施例１よりやや銅濃度が高くなった。また、汚泥発生量は約９８００ｍｇ／Ｌであり、実施例１より汚泥発生量が増加した。実施例１の廃液と比較して廃液中の銅濃度が低いにもかかわらず、汚泥発生量が増加した。この原因としてカルシウムが水酸化カルシウムまたは不溶性のカルシウム塩として析出したことが考えられ、不溶性の塩を形成しにくい水酸化ナトリウムを用いた実施例１と比較して汚泥発生量が増加したと考えられる。
Comparative Example 1
In Comparative Example 1, a waste liquid containing copper as a heavy metal and monoethanolamine as a complexing agent was treated. The properties of the waste liquid were pH 6.5, copper concentration 220 mg / L, and CODCr 50,200 mg / L. The treatment waste liquid in Comparative Example 1 had the same components as in Example 1, but was slightly lower in copper concentration and CODCr concentration.
In Comparative Example 1, iron (II) chloride was added to the waste liquid so that the molar ratio of iron was about 12 times the copper in the waste liquid. Thereafter, hydrochloric acid was added to lower the pH to about 2 to 3, and left for 5 minutes or longer. Next, calcium hydroxide was added to the waste liquid to adjust the pH to 10. After adjusting the pH, the slurry deposited by coagulation precipitation was separated and removed to obtain treated water. When the treated water was analyzed, the copper concentration was 0.5 mg / L, and the copper concentration was slightly higher than Example 1. Moreover, the amount of sludge generation was about 9800 mg / L, and the amount of sludge generation increased from Example 1. Although the copper concentration in the waste liquid was low compared with the waste liquid of Example 1, the amount of sludge generated increased. This may be because calcium is precipitated as calcium hydroxide or an insoluble calcium salt, and it is considered that the amount of sludge generated is increased as compared with Example 1 using sodium hydroxide which hardly forms an insoluble salt. .
実施例２
実施例２では、実施例１と同様に重金属として銅、錯化剤としてモノエタノールアミンを含む廃液を処理した。廃液の性状は、ｐＨが１３．７、銅濃度が２，１６０ｍｇ／Ｌ、ＣＯＤＣｒが１３８，０００ｍｇ／Ｌであった。
本廃液の処理に当たり、まず最初に廃液のｐＨを約６に調整し、析出したスラリーを凝集沈殿により分離・除去した。この処理により、廃液中の銅イオン濃度は約３５０ｍｇ／Ｌに低減した。次に、スラリーを分離・除去したあとの廃液（処理水）に塩化鉄（II）を添加した。この時の塩化鉄（II）の添加量は、銅に対する鉄量がモル比で約２．７倍になるように設定した。次に塩酸を添加し、ｐＨを２〜３程度に低下させ５分間放置した。
次に、当該廃液に水酸化ナトリウムを添加しｐＨを１０に調整した。ｐＨ調整後、析出したスラリーを再度凝集沈殿させ、分離・除去した後に処理水を得た。処理水を分析したところ、銅濃度は０．２ｍｇ／Ｌであり、良好な水質の処理水が得られた。
Example 2
In Example 2, as in Example 1, a waste liquid containing copper as a heavy metal and monoethanolamine as a complexing agent was treated. As for the properties of the waste liquid, the pH was 13.7, the copper concentration was 2,160 mg / L, and the CODCr was 138,000 mg / L.
In the treatment of this waste liquid, first, the pH of the waste liquid was adjusted to about 6, and the precipitated slurry was separated and removed by coagulation precipitation. By this treatment, the copper ion concentration in the waste liquid was reduced to about 350 mg / L. Next, iron (II) chloride was added to the waste liquid (treated water) after separating and removing the slurry. The amount of iron (II) chloride added at this time was set so that the amount of iron to copper was about 2.7 times in molar ratio. Next, hydrochloric acid was added to lower the pH to about 2 to 3, and left for 5 minutes.
Next, sodium hydroxide was added to the waste liquid to adjust the pH to 10. After adjusting the pH, the precipitated slurry was agglomerated again, separated and removed to obtain treated water. When the treated water was analyzed, the copper concentration was 0.2 mg / L, and treated water with good water quality was obtained.
実施例３
実施例３では、実施例２と同じ排液を処理した。すなわち、重金属として銅、錯化剤としてモノエタノールアミンを含む廃液を処理した。廃液の性状は、ｐＨが１３．７、銅濃度が２，１６０ｍｇ／Ｌ、ＣＯＤＣｒが１３８，０００ｍｇ／Ｌであった。
実施例３では、最初にｐＨを約６に調整したのち、塩化鉄（II）を添加した。塩化鉄（II）の添加量は実施例２と同様に銅に対する鉄量がモル比で約２．７倍量となるように設定した。次に塩酸を添加し、ｐＨを２〜３程度に低下させ５分間放置した。
次に、当該廃液に水酸化ナトリウムを添加しｐＨを１０に調整した。ｐＨ調整後、析出したスラリーを凝集沈殿させ、分離・除去した後に処理水を得た。処理水を分析したところ、銅濃度は７７ｍｇ／Ｌであった。実施例３では、銅除去は可能であるものの、実施例２と比較してみると残留している銅の量がわずかに多くなっている。
Example 3
In Example 3, the same effluent as in Example 2 was treated. That is, a waste liquid containing copper as a heavy metal and monoethanolamine as a complexing agent was treated. As for the properties of the waste liquid, the pH was 13.7, the copper concentration was 2,160 mg / L, and the CODCr was 138,000 mg / L.
In Example 3, the pH was first adjusted to about 6, and then iron (II) chloride was added. The amount of iron (II) chloride added was set so that the amount of iron with respect to copper was about 2.7 times the molar ratio as in Example 2. Next, hydrochloric acid was added to lower the pH to about 2 to 3, and left for 5 minutes.
Next, sodium hydroxide was added to the waste liquid to adjust the pH to 10. After adjusting the pH, the precipitated slurry was coagulated and precipitated, separated and removed to obtain treated water. When the treated water was analyzed, the copper concentration was 77 mg / L. In Example 3, although copper removal is possible, when compared with Example 2, the amount of remaining copper is slightly increased.
実施例４
実施例４では、実施例１と同じ廃液を処理した。すなわち、重金属として銅、錯化剤としてモノエタノールアミンを含む廃液を処理した。廃液の性状は、ｐＨが６．５、銅濃度が３５５ｍｇ／Ｌ、ＣＯＤＣｒが７７，４００ｍｇ／Ｌであった。
当該廃液の処理操作は、当該廃液に塩化鉄（II）を廃液中の銅に対し、鉄のモル比が約１１倍量となるように添加した。その後、塩酸を添加しｐＨを２〜４．５の間で変化させた。その後、実施例１と同様の操作を行い、処理水を得た。
処理水のｐＨと銅濃度の関係を図３に示す。図３に示すように塩化鉄（II）を添加した後のｐＨ調整では、ｐＨを２〜４．５の間で変化させているが、ｐＨが低いほど処理水中の銅濃度が低くなる傾向が認められた。例えば、処理水中の銅濃度を０．５ｍｇ/Ｌ未満とするためには、塩化鉄添加後のｐＨを３．５以下にするとよいことが図３のグラフより確認された。以上の結果より、必要とされる処理水の銅濃度に応じて、塩化鉄を添加した後のｐＨ調整の度合いを変えるとよい。
Example 4
In Example 4, the same waste liquid as in Example 1 was treated. That is, a waste liquid containing copper as a heavy metal and monoethanolamine as a complexing agent was treated. The properties of the waste liquid were pH 6.5, copper concentration 355 mg / L, and CODCr 77,400 mg / L.
In the waste liquid treatment operation, iron (II) chloride was added to the waste liquid so that the molar ratio of iron was about 11 times the copper in the waste liquid. Thereafter, hydrochloric acid was added to change the pH between 2 and 4.5. Then, operation similar to Example 1 was performed and the treated water was obtained.
The relationship between the pH of treated water and the copper concentration is shown in FIG. As shown in FIG. 3, in pH adjustment after adding iron (II) chloride, the pH is changed between 2 and 4.5, but the lower the pH, the lower the copper concentration in the treated water tends to be. Admitted. For example, in order to make the copper concentration in the treated water less than 0.5 mg / L, it was confirmed from the graph of FIG. From the above results, the degree of pH adjustment after adding iron chloride may be changed according to the required copper concentration of the treated water.
実施例５
実施例５では、重金属として銅、錯化剤としてモノエタノールアミンを含む廃液を処理した。廃液の性状は、ｐＨが６、銅濃度が４６６ｍｇ／Ｌであった。
当該廃液の処理操作においては、当該廃液に塩化鉄（II）を廃液中の銅に対し、鉄のモル比で約４〜１０倍量となるように添加した。その後、塩酸を添加しｐＨを２程度に低下させ、５分以上放置した。
次に、当該廃液に水酸化ナトリウムを添加しｐＨを１０に調整した。ｐＨ調整後、凝集沈殿により析出したスラリーを分離・除去し、処理水を得た。
廃液中の銅に対して添加する鉄のモル比を約４〜１０倍量の間で変化させ、処理水の銅濃度を調べた。鉄／銅のモル比と処理水の銅濃度の関係を図５に示す。図５に示すように鉄添加量が増えるに従い処理水銅濃度が低下する傾向が認められ、鉄／銅比が８．７以上で処理水銅濃度が１ｍｇ／Ｌ以下になった。
Example 5
In Example 5, a waste liquid containing copper as a heavy metal and monoethanolamine as a complexing agent was treated. The properties of the waste liquid were
In the waste liquid treatment operation, iron (II) chloride was added to the waste liquid so that the molar ratio of iron was about 4 to 10 times that of copper in the waste liquid. Thereafter, hydrochloric acid was added to lower the pH to about 2 and left for 5 minutes or longer.
Next, sodium hydroxide was added to the waste liquid to adjust the pH to 10. After adjusting the pH, the slurry deposited by coagulation precipitation was separated and removed to obtain treated water.
The molar ratio of iron added to the copper in the waste liquid was changed between about 4 to 10 times the amount, and the copper concentration of the treated water was examined. The relationship between the iron / copper molar ratio and the copper concentration of the treated water is shown in FIG. As shown in FIG. 5, the treatment water copper concentration tended to decrease as the iron addition amount increased, and the treatment water copper concentration became 1 mg / L or less at an iron / copper ratio of 8.7 or more.
実施例６
実施例６では、実施例１と同じ廃液を処理した。すなわち、重金属として銅、錯化剤としてモノエタノールアミンを含む廃液を処理した。廃液の性状は、ｐＨが６．５、銅濃度が３５５ｍｇ／Ｌ、ＣＯＤＣｒが７７，４００ｍｇ／Ｌであった。
当該廃液の処理操作においては、当該廃液に硫酸鉄（II）を廃液中の銅に対し、鉄のモル比が約１１倍量となるように添加した。その後、塩酸を添加しｐＨを２〜３程度に低下させ、５分以上放置した。
次に、当該廃液に水酸化ナトリウムを添加しｐＨを１０に調整した。ｐＨ調整後、凝集沈殿により析出したスラリーを分離・除去し、処理水を得た。処理水を水質分析したところ、銅濃度は０．３ｍｇ／Ｌであり、塩化鉄の添加に代えて硫酸鉄を添加しても本法による処理が可能であった。
Example 6
In Example 6, the same waste liquid as in Example 1 was treated. That is, a waste liquid containing copper as a heavy metal and monoethanolamine as a complexing agent was treated. The properties of the waste liquid were pH 6.5, copper concentration 355 mg / L, and CODCr 77,400 mg / L.
In the waste liquid treatment operation, iron (II) sulfate was added to the waste liquid so that the molar ratio of iron was about 11 times the copper in the waste liquid. Thereafter, hydrochloric acid was added to lower the pH to about 2 to 3, and left for 5 minutes or longer.
Next, sodium hydroxide was added to the waste liquid to adjust the pH to 10. After adjusting the pH, the slurry deposited by coagulation precipitation was separated and removed to obtain treated water. When the water quality of the treated water was analyzed, the copper concentration was 0.3 mg / L, and treatment by this method was possible even when iron sulfate was added instead of iron chloride.
実施例７
実施例７では、実施例１と同じ廃液を処理した。すなわち、重金属として銅、錯化剤としてモノエタノールアミンを含む廃液を処理した。廃液の性状は、ｐＨが６．５、銅濃度が３５５ｍｇ／Ｌ、ＣＯＤＣｒが７７，４００ｍｇ／Ｌであった。
当該廃液の処理操作においては、当該廃液に塩化鉄（III）を廃液中の銅に対し、鉄のモル比が約８倍量となるように添加した。その後、塩酸を添加しｐＨを２程度に低下させ、３０分以上放置した。
次に、当該廃液に水酸化ナトリウムを添加しｐＨを１０に調整した。ｐＨ調整後、凝集沈殿により析出したスラリーを分離・除去し、処理水を得た。処理水を水質分析したところ、銅濃度は約１００ｍｇ／Ｌであり、塩化鉄（II）を添加した実施例１と比較して銅濃度が高くなったものの塩化鉄（III）でも本法による銅の低減が可能であった。
Example 7
In Example 7, the same waste liquid as Example 1 was processed. That is, a waste liquid containing copper as a heavy metal and monoethanolamine as a complexing agent was treated. The properties of the waste liquid were pH 6.5, copper concentration 355 mg / L, and CODCr 77,400 mg / L.
In the waste liquid treatment operation, iron (III) chloride was added to the waste liquid so that the molar ratio of iron was about 8 times the copper in the waste liquid. Thereafter, hydrochloric acid was added to lower the pH to about 2 and left for 30 minutes or longer.
Next, sodium hydroxide was added to the waste liquid to adjust the pH to 10. After adjusting the pH, the slurry deposited by coagulation precipitation was separated and removed to obtain treated water. When the water quality of the treated water was analyzed, the copper concentration was about 100 mg / L, and the copper concentration was higher than that in Example 1 to which iron (II) chloride was added, but iron (III) was also used in this method. Can be reduced.
これまで本発明の実施形態について説明したが、本発明は上述の実施形態に限定されず、その技術思想の範囲内において、種々の異なる形態で実施されてよいことは勿論である。 Although the embodiment of the present invention has been described so far, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention may be implemented in various different forms within the scope of the technical idea.
１ 反応槽
２，２３，３５ 固液分離装置
２１ 第一の反応槽
３１ 第二の反応槽
１０ 重金属含有廃液
１１，３２ 鉄塩供給配管
１２，３３ 酸供給配管
１３，３４ アルカリ金属水酸化物供給配管
１４，３６ 処理水
１５，２５，３７ スラリー
DESCRIPTION OF SYMBOLS 1
11, 32 Iron
Claims (5)
前記反応槽において廃液に酸を添加しｐＨを６〜７の中性付近に調整し、当該廃液に鉄塩を添加した後、混合廃液のｐＨが２〜４になるように酸を添加し、アルカリ金属の水酸化物を添加し、ｐＨを１０以上のアルカリ条件に上昇させ、前記廃液から重金属類と鉄を含む固形物を沈殿させ、前記固液分離装置において前記廃液より重金属類を分離・除去することを特徴とする重金属含有廃液の処理装置。 A waste liquid treatment apparatus containing a heavy metal and a complexing agent that forms a complex with a heavy metal, a reaction tank containing the waste liquid, a pipe for supplying an iron salt, a pipe for supplying an acid, an alkali metal A pipe for supplying hydroxide and a solid-liquid separator;
In the reaction tank, an acid is added to the waste liquid to adjust the pH to around neutrality of 6 to 7, and after adding an iron salt to the waste liquid, an acid is added so that the pH of the mixed waste liquid becomes 2 to 4, Add alkali metal hydroxide , raise the pH to 10 or more alkaline conditions, precipitate solids containing heavy metals and iron from the waste liquid, and separate heavy metals from the waste liquid in the solid-liquid separator. An apparatus for treating heavy metal-containing waste liquid, which is characterized by being removed.
廃液を収容する第一の反応槽と、酸を供給する配管と、ｐＨ測定手段と、廃液のｐＨに応じて酸の供給量を制御する制御装置と、第一の固液分離装置とを備え、
廃液を収容する第二の反応槽と、鉄塩を供給する配管と、アルカリ金属の水酸化物を供給する配管と、第二の固液分離装置とをさらに備え、
前記第一の反応槽において廃液に酸を添加しｐＨを６〜７の中性付近に調整し、廃液中の析出物を前記第一の固液分離装置で分離した後、前記析出物を分離した後の上澄液としての廃液を前記第二の反応槽に移送し、
前記第二の反応槽において前記廃液に鉄塩を添加した後、酸を添加して廃液のｐＨを２〜４に下げた後にアルカリ金属の水酸化物を添加し、ｐＨを１０以上のアルカリ条件に上昇させ、前記廃液から重金属類と鉄を含む固形物を沈殿させ、前記第二の固液分離装置により前記廃液より重金属類を分離・除去することを特徴とする重金属含有廃液の処理装置。 An apparatus for treating waste liquid containing heavy metals and a complexing agent that forms a complex with heavy metals,
A first reaction tank containing waste liquid, piping for supplying acid, pH measuring means, a control device for controlling the supply amount of acid according to the pH of the waste liquid, and a first solid-liquid separation device. ,
A second reaction vessel containing waste liquid, a pipe for supplying iron salt, a pipe for supplying an alkali metal hydroxide, and a second solid-liquid separator,
In the first reaction tank, an acid is added to the waste liquid to adjust the pH to about 6 to 7 , and the precipitate in the waste liquid is separated by the first solid-liquid separator, and then the precipitate is separated. The waste liquid as the supernatant after the transfer to the second reaction tank,
The second after addition of iron salts to the waste liquid in the reaction vessel, by adding an acid was added to alkali metal hydroxide after lowering the pH of the waste liquid 2 to 4, pH of 10 or more alkaline conditions raised to, solids containing heavy metals and iron is precipitated from the waste liquid, the second solid-liquid separation device by the processing unit of a heavy metal-containing waste liquid, which comprises separating and removing heavy metals from the waste liquid.
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