JP6061024B2 - Method and apparatus for treating wastewater containing heavy metals - Google Patents
Method and apparatus for treating wastewater containing heavy metals Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/76—Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/20—Heavy metals or heavy metal compounds
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Description
本発明は、排水、特に重金属含有排水の処理方法及び処理装置に関する。
本願は、2014年2月27日に日本に出願された特願2014−036853号に基づき優先権を主張し、その内容をここに援用する。The present invention relates to a method and apparatus for treating wastewater, particularly heavy metal-containing wastewater.
This application claims priority based on Japanese Patent Application No. 2014-036853 for which it applied to Japan on February 27, 2014, and uses the content here.
産業上さまざまな分野で使用される重金属は、人体や環境に有害な影響を及ぼすものが多く存在している。したがって、これらを含有する排水を下水道や公共用水域に排出する際には、排水基準、すなわち下水道法又は水質汚濁防止法等、各国法令に定める排水基準の適用を受けることになり、何らかの処理が必要となる。
さらに、地域によっては環境汚染に対する懸念から規制を強化し、前記排水基準を上回る厳しい基準で上乗せ規制を課す事例がある。
このように、重金属含有排水の排出は、より一層厳しく規制されるような状況にある。特に、日本では、下水道法において、亜鉛について亜鉛及びその化合物として2mg/L以下、銅について銅及びその化合物として3mg/L以下と、また、中国では、亜鉛について2mg/L以下、銅について0.5mg/L以下と、厳しい水質基準が定められており、有効な処理技術が求められている。Many heavy metals used in various industrial fields have harmful effects on the human body and the environment. Therefore, when wastewater containing these materials is discharged into sewers or public water bodies, wastewater standards, that is, wastewater standards such as the Sewerage Law or Water Pollution Control Law, etc. are applied, and some treatment Necessary.
Furthermore, in some regions, there are cases where regulations are tightened due to concerns about environmental pollution, and regulations are imposed with strict standards exceeding the above effluent standards.
Thus, the discharge of waste water containing heavy metals is in a situation where it is more strictly regulated. In particular, in Japan, in the sewerage law, zinc and its compound are 2 mg / L or less for zinc, copper and its compound are 3 mg / L or less for copper, and in China, 2 mg / L or less for zinc and 0. Strict water quality standards of 5 mg / L or less are established, and effective treatment techniques are required.
これらの問題に対し、効率的な重金属含有排水からの亜鉛及び銅の処理方法が提案されてきた。
例えば、重金属含有排水からの亜鉛及び銅の処理方法としては、金属鉱山排水の処理方法であって、酸性で重金属を含んだ金属鉱山排水を第1の容器内に供給しながら、該排水中の2価の鉄イオンの一部を3価の鉄イオンに酸化する処理を行った後、該排水を第2の容器に投入し、該排水のpHを3〜5にコントロールして砒素と3価の鉄イオンの化合物を析出させた後、該析出物を固液分離する処理を行い、液分を第3の容器に投入し、該排水のpHを3〜5にコントロールし、鉄酸化細菌を添加し、空気を吹き込み、2価の鉄イオンを3価の鉄イオンに酸化すると同時に鉄水酸化物を析出させた後、該析出物を固液分離する処理を行い、液分を第4の容器に投入し、該排水のpHを6〜10にコントロールし、銅、亜鉛の少なくとも1種の元素を金属水酸化物として析出させる亜鉛及び銅の処理方法が挙げられる(特許文献1)。In response to these problems, an efficient method for treating zinc and copper from heavy metal-containing wastewater has been proposed.
For example, as a method for treating zinc and copper from heavy metal-containing wastewater, it is a method for treating metal mine wastewater. While supplying metal mine wastewater containing acid and heavy metals into the first container, After the treatment to oxidize part of the divalent iron ions to trivalent iron ions, the waste water is put into the second container, and the pH of the waste water is controlled to 3 to 5 to control arsenic and trivalent. After the precipitation of the iron ion compound, the precipitate is subjected to a solid-liquid separation process, the liquid is put into a third container, the pH of the waste water is controlled to 3 to 5, and the iron-oxidizing bacteria are removed. And after blowing air and oxidizing the divalent iron ion to the trivalent iron ion and precipitating the iron hydroxide at the same time, the precipitate is subjected to a solid-liquid separation process. Put into a container, control the pH of the waste water to 6-10, at least one of copper and zinc Zinc and processing method of the copper to precipitate the elemental metal hydroxides (Patent Document 1).
しかし、前記方法では、反応を多段階で行う必要があるため処理装置が複雑となり、また排水中の夾雑物、特にビルダーと呼ばれるキレート剤などの金属錯体を形成する化合物が存在する場合、排水中の亜鉛及び銅の処理が困難であった。特に、亜鉛及び銅は夾雑物の存在下では、不溶化する際のpHが理論値通りとならず、処理が極めて困難であった。 However, in the above method, the treatment apparatus is complicated because it is necessary to carry out the reaction in multiple stages, and in the wastewater, there are impurities in the wastewater, particularly when a compound forming a metal complex such as a chelating agent called a builder exists. It was difficult to treat zinc and copper. In particular, zinc and copper were extremely difficult to treat in the presence of impurities because the pH at the time of insolubilization did not become the theoretical value.
排水中の亜鉛及び銅を除去する方法として、様々な方法が検討されているが、これらの方法は、排水中の夾雑物による影響を受けやすく、夾雑物の影響を小さくするためには工程の煩雑化、コスト高騰を招くという問題がある。
本発明は、このような従来の課題を解決することを目的とする。Various methods have been studied for removing zinc and copper in wastewater, but these methods are easily affected by contaminants in the wastewater. There is a problem of incurring complexity and cost increase.
An object of the present invention is to solve such a conventional problem.
本発明は、簡便、かつ、高い処理効率で、排水、特に重金属含有排水、とりわけ亜鉛及び銅を含有する排水から、重金属、特に亜鉛及び銅を除去できる排水処理方法を提供する。 The present invention provides a wastewater treatment method capable of removing heavy metals, particularly zinc and copper, from wastewater, particularly heavy metal-containing wastewater, particularly wastewater containing zinc and copper, with high treatment efficiency.
すなわち、本発明は、下記態様を有する。
[1]下記工程(i)及び(ii)を含む、亜鉛及び銅を含有する排水中から、亜鉛及び銅を除去する排水処理方法:
(i)前記排水に、酸化剤及び、マグネシウム及び/又はこれらの塩である共沈剤を作用させ、前記排水中の亜鉛及び銅を不溶化させる、不溶化工程;及び
(ii)前記工程(i)に付した排水から、膜濾過により前記不溶化した亜鉛及び銅を除去する、分離工程。
[2]前記不溶化工程に、pH調整工程を含む、[1]に記載の排水処理方法。
[3]前記排水が、キレート剤を含むものである、[1]又は[2]に記載の排水処理方法。
[4]前記排水が、めっき排水である、[1]〜[3]の何れか一項に記載の排水処理方法。
[5]前記酸化剤が、塩素酸化物、塩素酸類及びこれらの塩、並びに過酸化水素からなる群から一種以上選択される、[1]〜[4]の何れか一項に記載の排水処理方法。
[6]前記不溶化工程において、排水のpHを10より大きく、かつ、13以下になるように調整する[1]〜[5]の何れか一項に記載の排水処理方法。
[7]前記不溶化工程において、前記酸化剤の作用量が、前記排水中の銅濃度に対して、モル当量比で0.5倍以上20倍以下である、[1]〜[6]の何れか一項に記載の排水処理方法。
[8]前記不溶化工程において、前記共沈剤の作用量が、前記排水中の亜鉛濃度に対して、モル当量比で20倍以上1000倍以下である、[1]〜[7]の何れか一項に記載の排水処理方法。
[9]前記排水中に含まれる亜鉛の95重量%以上、及び、前記排水中に含まれる銅の80重量%以上を同時に除去する、[1]〜[8]の何れか一項に記載の排水処理方法。
[10]酸化剤を作用させる酸化槽、マグネシウム及び/又はこれらの塩である共沈剤を作用させる共沈槽、亜鉛及び銅を不溶化させる不溶化槽、並びに、不溶化した亜鉛及び銅を膜濾過により除去する分離装置を有する、亜鉛及び銅を含有する排水中から、亜鉛及び銅を除去する排水処理装置。
[11]酸化剤を作用させる酸化槽、マグネシウム及び/又はこれらの塩である共沈剤を作用させる共沈槽、亜鉛及び銅を不溶化させる不溶化槽、並びに、不溶化した亜鉛及び銅を膜濾過により除去する分離装置のうち、2つ以上の槽又は装置が一体となった、[10]に記載の排水処理装置。
[12]亜鉛及び銅を不溶化させる不溶化槽に、酸又はアルカリを添加して槽内のpHを調整する、pH調整手段を持つ[10]又は[11]に記載の排水処理装置。
That is, this invention has the following aspect.
[1] A wastewater treatment method for removing zinc and copper from wastewater containing zinc and copper, including the following steps (i) and (ii):
(I) an insolubilization step in which an oxidizing agent and a coprecipitation agent that is magnesium and / or a salt thereof are allowed to act on the wastewater to insolubilize zinc and copper in the wastewater; and (ii) the step (i) A separation step of removing the insolubilized zinc and copper from the waste water attached to the membrane by membrane filtration .
[2] The wastewater treatment method according to [1], wherein the insolubilization step includes a pH adjustment step.
[ 3 ] The wastewater treatment method according to [1] or [2] , wherein the wastewater contains a chelating agent.
[ 4 ] The wastewater treatment method according to any one of [1] to [ 3 ], wherein the wastewater is plating wastewater.
[ 5 ] The waste water treatment according to any one of [1] to [ 4 ], wherein the oxidizing agent is selected from the group consisting of chlorine oxides, chloric acids and salts thereof, and hydrogen peroxide. Method.
[ 6 ] The wastewater treatment method according to any one of [1] to [ 5 ], wherein the pH of the wastewater is adjusted to be greater than 10 and 13 or less in the insolubilization step.
[ 7 ] In any one of [1] to [ 6 ], in the insolubilization step, the amount of action of the oxidizing agent is 0.5 to 20 times in terms of molar equivalent ratio with respect to the copper concentration in the waste water. The waste water treatment method according to claim 1.
[ 8 ] In the insolubilization step, any one of [1] to [ 7 ], wherein the amount of action of the coprecipitation agent is 20 to 1000 times in terms of molar equivalent ratio with respect to the zinc concentration in the waste water. The wastewater treatment method according to one item.
[ 9 ] 95% by weight or more of zinc contained in the waste water and 80% by weight or more of copper contained in the waste water are simultaneously removed, [1] to [ 8 ] Wastewater treatment method.
[ 10 ] Oxidation tank in which oxidant is allowed to act, coprecipitation tank in which coprecipitate is made of magnesium and / or salts thereof, insolubilization tank in which zinc and copper are insolubilized, and insolubilized zinc and copper by membrane filtration A wastewater treatment device for removing zinc and copper from wastewater containing zinc and copper, having a separation device for removal.
[ 11 ] Oxidation tank in which an oxidizing agent is applied, coprecipitation tank in which a coprecipitation agent that is magnesium and / or a salt thereof is applied, an insolubilization tank in which zinc and copper are insolubilized, and insolubilized zinc and copper by membrane filtration The waste water treatment apparatus according to [ 10 ], in which two or more tanks or apparatuses are integrated in the separation apparatus to be removed.
[ 12 ] The waste water treatment apparatus according to [ 10 ] or [ 11 ], having pH adjusting means for adjusting pH in the tank by adding acid or alkali to an insolubilizing tank for insolubilizing zinc and copper.
本発明の排水処理方法によれば、簡便、かつ、高い効率で排水から重金属を除去することができる。特に、本発明の排水処理方法によれば、排水中の亜鉛および銅を、それぞれ95重量%以上及び80重量%以上、97重量%以上及び82.5重量%以上、97.3重量%以上及び85.0重量%以上、98重量%以上及び88重量%以上、あるいは98.7重量%以上及び88.5重量%以上除去することができる。 According to the wastewater treatment method of the present invention, heavy metals can be removed from wastewater easily and with high efficiency. In particular, according to the wastewater treatment method of the present invention, zinc and copper in the wastewater are 95% by weight or more and 80% by weight or more, 97% by weight or more, 82.5% by weight or more, 97.3% by weight or more, respectively. 85.0 wt% or more, 98 wt% or more and 88 wt% or more, or 98.7 wt% or more and 88.5 wt% or more can be removed.
以下、本発明の排水処理方法について説明する。
本発明の排水処理方法は、排水、特に重金属含有排水、とりわけ亜鉛及び銅を含有する排水中から、重金属、特に亜鉛及び銅を除去する方法であり、下記工程(i)及び(ii)を含むものである。
(i)排水に、酸化剤及び共沈剤を作用させ、前記排水中の重金属を不溶化させる、不溶化工程;及び
(ii)前記工程(i)に付した排水から前記不溶化した重金属を除去する、分離工程。
なお、本発明の排水処理方法には、処理の対象となる排水に対して、不溶化工程において作用させる酸化剤及び共沈剤の作用量を決定するための処理前重金属濃度測定工程、及び/又は、分離工程後の排水における重金属の除去率を決定するための処理後重金属濃度測定工程を含んでもよい。これらの濃度測定工程における排水における重金属の濃度の測定方法は、JIS K 0102に従って、あるいは準じて行うことができ、特に亜鉛についてはJIS K 0102−53.3に従って、銅についてはJIS K 0102−52.4に従って、その濃度を決定することができる。これらの測定は、コンピュータを用いたモニタリングを介して行うこともできる。Hereinafter, the waste water treatment method of the present invention will be described.
The wastewater treatment method of the present invention is a method for removing heavy metals, particularly zinc and copper, from wastewater, particularly heavy metal-containing wastewater, especially wastewater containing zinc and copper, and includes the following steps (i) and (ii): It is a waste.
(I) an oxidant and a coprecipitation agent are allowed to act on the wastewater to insolubilize heavy metals in the wastewater; and (ii) the insolubilized heavy metals are removed from the wastewater subjected to the step (i). Separation process.
In the wastewater treatment method of the present invention, the pretreatment heavy metal concentration measurement step for determining the amount of action of the oxidizing agent and the coprecipitation agent to act on the wastewater to be treated in the insolubilization step, and / or A post-treatment heavy metal concentration measurement step for determining the removal rate of heavy metals in the waste water after the separation step may be included. The method for measuring the concentration of heavy metals in the waste water in these concentration measurement steps can be performed according to JIS K 0102 or according to JIS K 0102-53.3, particularly for zinc, and JIS K 0102-52 for copper. The concentration can be determined according to .4. These measurements can also be performed through monitoring using a computer.
本発明の排水処理方法で処理される排水は、重金属含有排水であることが好ましく、なかでも、少なくとも亜鉛および銅を含有する排水であることが好ましい。ここで、重金属としては、比重が4以上の金属であり、クロム、銅、亜鉛、カドミウム、ニッケル、水銀、鉛、鉄などが挙げられる。これら重金属は単独で含まれていてもよいが、通常は複数の重金属が混合された状態で含まれている。また、本発明の排水処理方法により排水から除去される重金属としては、亜鉛及び銅を挙げることができる。また、本発明の排水処理方法で処理される排水は、後述するキレート剤を含むものであってもよい。また、本発明の排水処理方法で処理される排水は、後述するめっき排水であってもよい。 The wastewater to be treated by the wastewater treatment method of the present invention is preferably heavy metal-containing wastewater, and in particular, wastewater containing at least zinc and copper is preferred. Here, the heavy metal is a metal having a specific gravity of 4 or more, and includes chromium, copper, zinc, cadmium, nickel, mercury, lead, iron and the like. These heavy metals may be contained alone, but are usually contained in a state where a plurality of heavy metals are mixed. Moreover, zinc and copper can be mentioned as a heavy metal removed from waste water by the waste water treatment method of this invention. Moreover, the waste water treated by the waste water treatment method of the present invention may contain a chelating agent described later. Further, the wastewater treated by the wastewater treatment method of the present invention may be plating wastewater described later.
<不溶化工程>
本発明の排水処理方法における工程(i)は、排水、特に重金属含有排水、とりわけ亜鉛及び銅を含有する排水に、酸化剤及び共沈剤を作用させ、前記排水中の重金属、特に亜鉛及び銅を不溶化させる、不溶化工程である。<Insolubilization process>
In step (i) in the wastewater treatment method of the present invention, an oxidizing agent and a coprecipitation agent are allowed to act on wastewater, particularly heavy metal-containing wastewater, particularly wastewater containing zinc and copper, and heavy metals in the wastewater, particularly zinc and copper. It is an insolubilization process which insolubilizes.
(酸化剤)
本発明で使用される酸化剤とは、酸素原子を転移される化合物又は酸化還元反応において電子を得る物質であり、二酸化塩素などの塩素酸化物;次亜塩素酸、亜塩素酸、塩素酸、過塩素酸を含む塩素酸類及びこれらの塩;過酸化水素;フェントン;オゾン;UVや光触媒により発生するラジカル等からなる群より選択される。また、これらの酸化剤は、単独で用いてもよいし、複数の酸化剤を混合して用いてもよい。これにより、金属キレートが破壊され、そこに共沈剤を作用させることで重金属の不溶化を促進することが可能となると考えられる。
なかでも、取り扱い性及び入手容易性の観点から、塩素酸類又はこれらの塩が好ましい。塩素酸類の塩としては、ナトリウム塩、カリウム塩、カルシウム塩、マグネシウム塩、アンモニウム塩等を挙げることができ、次亜塩素酸ナトリウムがより好ましい。
また、これらの酸化剤は溶剤に溶解した溶液として用いることもできる。その場合、取り扱い性及び入手容易性の観点から、水溶液を用いることが好ましい。特に酸化剤として、次亜塩素酸ナトリウム水溶液を用いることが好ましい。
酸化剤を溶液として用いる際の濃度は、酸化剤溶液を排水に作用した際に所望の排水中濃度に調整できる濃度であればよい。
これらの酸化剤を用いれば、酸化反応が速やかに進行しやすくなり、全体の処理速度を速めることができる。
また、これらは、EDTA、酒石酸などのキレート作用を有する錯体形成化合物の分解効率が高いことから、重金属の不溶化工程において、錯体形成化合物による不溶化物の凝集阻害を防ぐことができる。このため、分離工程のための不溶化処理をより効率的に行うことができる。
また、特に次亜塩素酸ナトリウム又はその溶液を酸化剤として用いると、重金属の不溶化工程において生成する重金属の不溶化物の粒子径が大きくなる傾向にある。不溶化物の粒子径が大きい方が、後述する膜分離工程において濾過膜の細孔が閉塞されるのを抑制でき、膜の流束を高く維持できる。(Oxidant)
The oxidizing agent used in the present invention is a compound capable of transferring an oxygen atom or a substance that obtains electrons in an oxidation-reduction reaction, and chlorine oxide such as chlorine dioxide; hypochlorous acid, chlorous acid, chloric acid, Chloric acids including perchloric acid and salts thereof; hydrogen peroxide; Fenton; ozone; selected from the group consisting of radicals generated by UV or photocatalyst. Moreover, these oxidizing agents may be used alone or in combination with a plurality of oxidizing agents. Thereby, the metal chelate is destroyed, and it is considered that insolubilization of heavy metals can be promoted by causing the coprecipitation agent to act on the metal chelate.
Of these, chloric acids or salts thereof are preferable from the viewpoints of handleability and availability. Examples of chloric acid salts include sodium salts, potassium salts, calcium salts, magnesium salts, ammonium salts, and the like, with sodium hypochlorite being more preferred.
These oxidizing agents can also be used as a solution dissolved in a solvent. In that case, it is preferable to use an aqueous solution from the viewpoints of handleability and availability. In particular, an aqueous sodium hypochlorite solution is preferably used as the oxidizing agent.
The concentration when the oxidant is used as the solution may be a concentration that can be adjusted to a desired concentration in the wastewater when the oxidant solution acts on the wastewater.
If these oxidizing agents are used, the oxidation reaction easily proceeds quickly, and the overall processing speed can be increased.
Moreover, since these have high decomposition efficiency of complex-forming compounds having a chelating action such as EDTA and tartaric acid, they can prevent the inhibition of aggregation of insolubilized substances by the complex-forming compounds in the heavy metal insolubilization step. For this reason, the insolubilization process for a separation process can be performed more efficiently.
In particular, when sodium hypochlorite or a solution thereof is used as the oxidizing agent, the particle size of the heavy metal insolubilized product generated in the heavy metal insolubilization step tends to increase. When the particle size of the insolubilized material is larger, it is possible to suppress clogging of the pores of the filtration membrane in the membrane separation step described later, and the membrane flux can be maintained high.
排水中への酸化剤及び共沈剤の作用順序については特に指定はないが、不溶化効率の観点から酸化剤の作用後に共沈剤を作用させることが好ましい。共沈剤を作用させるタイミングとしては、処理する排水の量にもよるが、通常室温若しくは外気温下、排水に酸化剤を作用させ、撹拌等により混合し、0.1〜50時間、好ましくは0.2〜30時間、より好ましくは0.5〜10時間程度放置した後、共沈剤を作用させてもよい。
また、本発明における重金属不溶化のためのpH調整工程の順序については特に指定はないが、調整のしやすさの観点から酸化剤及び共沈剤の作用工程後に行うことが望ましい。pH調整工程を行うタイミングとしては、処理する排水の量にもよるが、通常室温若しくは外気温下、酸化剤を作用させた排水に共沈剤を作用させ、撹拌等により混合し、0.1〜50時間、好ましくは0.2〜30時間、より好ましくは0.5〜10時間程度放置した後、pH調整工程を行ってもよい。
尚、「作用」とは、添加及び/又は混合することを意味する。The order of action of the oxidizing agent and the coprecipitation agent in the wastewater is not particularly specified, but it is preferable to act the coprecipitation agent after the action of the oxidizing agent from the viewpoint of insolubilization efficiency. The timing at which the coprecipitate is allowed to act depends on the amount of wastewater to be treated, but usually at room temperature or outside temperature, the oxidant is allowed to act on the wastewater and mixed by stirring, etc., for 0.1 to 50 hours, preferably The coprecipitation agent may be allowed to act after standing for about 0.2 to 30 hours, more preferably about 0.5 to 10 hours.
The order of the pH adjustment step for insolubilizing heavy metals in the present invention is not particularly specified, but it is desirable to carry out after the action step of the oxidizing agent and the coprecipitate from the viewpoint of ease of adjustment. The timing for performing the pH adjustment step depends on the amount of wastewater to be treated, but usually a coprecipitation agent is allowed to act on wastewater treated with an oxidant at room temperature or outside temperature, and mixed by stirring or the like. The pH adjustment step may be performed after leaving for about 50 hours, preferably 0.2 to 30 hours, more preferably about 0.5 to 10 hours.
The “action” means addition and / or mixing.
酸化剤の作用量としては、排水中の銅濃度に対して、モル当量比で0.5〜20倍の濃度となることが好ましく、1.0〜15倍がより好ましく、1.2〜14倍がさらに好ましく、3.3〜7.0倍が特に好ましい。
酸化剤の作用量が下限値以上であれば、総じて排水中からの亜鉛及び銅の除去効率を高くしやすいが、特に排水中からの銅の除去率を高くしやすい。また、酸化剤の作用量が上限値以下であれば、総じて排水中からの亜鉛及び銅の除去効率を高くしやすいが、特に亜鉛の除去率を高くしやすく、また酸化剤の供給量が少なく経済的である。
酸化剤は、酸化剤を作用させる酸化槽において作用させることができる。酸化槽は排水を貯留できるものであれば特に限定されないが、排水、及び酸化剤によって劣化しにくいものが好ましい。酸化槽への酸化剤の添加手段としては、固体として若しくは溶液等の液体混合物として酸化剤が添加できるものであれば、特に限定されない。The amount of action of the oxidizing agent is preferably 0.5 to 20 times the molar equivalent ratio, more preferably 1.0 to 15 times, and 1.2 to 14 with respect to the copper concentration in the waste water. Double is more preferable, and 3.3 to 7.0 is particularly preferable.
If the amount of action of the oxidizing agent is equal to or greater than the lower limit, it is easy to increase the removal efficiency of zinc and copper from the wastewater as a whole, but it is particularly easy to increase the removal rate of copper from the wastewater. In addition, if the amount of action of the oxidant is not more than the upper limit value, it is easy to increase the removal efficiency of zinc and copper from the waste water as a whole, but it is particularly easy to increase the removal rate of zinc and the supply amount of the oxidant is small. Economical.
An oxidizing agent can be made to act in the oxidation tank which makes an oxidizing agent act. The oxidation tank is not particularly limited as long as it can store wastewater, but is preferably one that is not easily deteriorated by wastewater and an oxidizing agent. The means for adding the oxidizing agent to the oxidation tank is not particularly limited as long as the oxidizing agent can be added as a solid or as a liquid mixture such as a solution.
(共沈剤)
本発明における共沈剤とは、排水中において、単独であれば沈殿しない重金属を、その存在により、自らが沈殿する際に重金属を共に沈殿させるものである。
本発明で使用される共沈剤は、アルカリ土類金属及び/又はこれらの塩である。即ち、これらの共沈剤は、単独で用いてもよいし、複数の共沈剤を混合して用いてもよい。
なかでも、アルカリ土類金属としては、取り扱い性、入手容易性の観点から、カルシウム、又はマグネシウムが好ましく、マグネシウムがより好ましい。アルカリ土類金属の塩としては、塩化物、臭化物等のハロゲン化物、硫酸塩、炭酸塩、硝酸塩、リン酸塩等を挙げることができる。特に、ハロゲン化物、なかでも塩化物が好ましく用いられ、塩化マグネシウムを用いることがより好ましい。
また、これらの共沈剤は溶剤に溶解した溶液として用いることもできる。その場合、取り扱い性及び入手容易性の観点から、水溶液を用いることが好ましい。特に共沈剤として、塩化マグネシウム、及び/又は塩化マグネシウム水溶液を用いることが好ましい。
共沈剤を溶液として用いる際の濃度は、共沈剤溶液を排水に作用させた際に所望の排水中濃度に調整できる濃度であればよい。
マグネシウム及び/若しくはこれらの塩を含むマグネシウム塩溶液を共沈剤として用いると、重金属の不溶化物を膜分離によって除去する際、スケールと呼ばれる無機塩による濾過膜の細孔の閉塞を抑制でき、膜の流束を高く維持することができる。(Coprecipitant)
The coprecipitation agent in the present invention is for precipitating heavy metals that do not precipitate if separated alone in the wastewater when they are precipitated by their presence.
The coprecipitant used in the present invention is an alkaline earth metal and / or a salt thereof. That is, these coprecipitates may be used alone or in combination with a plurality of coprecipitates.
Especially, as an alkaline-earth metal, calcium or magnesium is preferable from a viewpoint of handleability and availability, and magnesium is more preferable. Examples of alkaline earth metal salts include halides such as chlorides and bromides, sulfates, carbonates, nitrates, phosphates, and the like. In particular, halides, especially chlorides are preferably used, and magnesium chloride is more preferably used.
Moreover, these coprecipitation agents can also be used as a solution dissolved in a solvent. In that case, it is preferable to use an aqueous solution from the viewpoints of handleability and availability. In particular, it is preferable to use magnesium chloride and / or magnesium chloride aqueous solution as a coprecipitation agent.
The concentration when the coprecipitate is used as a solution may be a concentration that can be adjusted to a desired concentration in wastewater when the coprecipitate solution is allowed to act on the wastewater.
When a magnesium salt solution containing magnesium and / or a salt thereof is used as a coprecipitation agent, clogging of pores of the filtration membrane by inorganic salts called scales can be suppressed when removing insolubles of heavy metals by membrane separation. High flux can be maintained.
共沈剤の作用量としては、排水中の亜鉛濃度に対し、モル当量比で20〜1000倍の濃度となることが好ましく、40〜400倍がより好ましく、50〜200倍がさらに好ましく、80〜170倍が特に好ましい。
共沈剤の作用量が下限値以上であれば、排水中からの亜鉛及び銅の除去効率を高くしやすい。また、共沈剤の作用量が上限値以下であれば、共沈剤の供給量が少なく経済的である。
共沈剤は、共沈剤を作用させる共沈槽において作用させることができる。共沈槽は排水を貯留できるものであれば特に限定されないが、排水、酸化剤及び共沈剤によって劣化しにくいものが好ましい。共沈槽への共沈剤の添加手段としては、固体として若しくは溶液等の液体混合物として共沈剤が添加できるものであれば、特に限定されない。The amount of action of the coprecipitation agent is preferably 20 to 1000 times the molar equivalent ratio with respect to the zinc concentration in the waste water, more preferably 40 to 400 times, still more preferably 50 to 200 times, 80 -170 times is particularly preferable.
If the amount of action of the coprecipitation agent is equal to or greater than the lower limit value, it is easy to increase the efficiency of removing zinc and copper from the waste water. Moreover, if the amount of action of the coprecipitation agent is not more than the upper limit value, the supply amount of the coprecipitation agent is small and economical.
The coprecipitation agent can be made to act in a coprecipitation tank in which the coprecipitation agent acts. The coprecipitation tank is not particularly limited as long as it can store wastewater, but a coprecipitation tank that is not easily deteriorated by wastewater, an oxidizing agent, and a coprecipitation agent is preferable. The means for adding the coprecipitation agent to the coprecipitation tank is not particularly limited as long as the coprecipitation agent can be added as a solid or as a liquid mixture such as a solution.
重金属(例えば、亜鉛及び銅)の不溶化とは、酸化剤及び共沈剤を作用させた排水に不溶化剤を作用させ、排水中の重金属、とりわけ亜鉛及び銅を不溶化し、析出させることにより、濾過等による分離が可能な状態にすることを意味する。
不溶化の方法としては、水酸化剤を用いた水酸化物法と、硫化剤を用いた硫化物法がある。なお、硫化物法の場合は硫化水素発生の恐れがあるため、安全性の観点から、水酸化物法が好ましい。Insolubilization of heavy metals (for example, zinc and copper) is performed by insolubilizing heavy metals (especially zinc and copper) in the wastewater by causing the insolubilizer to act on the wastewater treated with the oxidizing agent and coprecipitation agent. This means that separation by such means is possible.
As the insolubilization method, there are a hydroxide method using a hydroxylating agent and a sulfide method using a sulfiding agent. In the case of the sulfide method, hydrogen sulfide may be generated, and therefore the hydroxide method is preferable from the viewpoint of safety.
水酸化物法は、水酸化剤(水酸化物イオン)と対象金属とを反応させ、溶解度の低い金属水酸化物として析出させる方法である。不溶化剤としての水酸化剤としては、水酸化ナトリウム、炭酸ナトリウム、水酸化カルシウム、水酸化マグネシウムなどが用いられる。スラッジ発生量が少なくなるため、水酸化ナトリウムによる水酸化物法が、より好ましい。
一方、硫化物法は、硫化剤(硫化物イオン)と対象金属を反応させ、溶解度の低い金属硫化物として析出させる方法である。不溶化剤としての硫化剤としては、硫化ナトリウム、硫化水素などが用いられる。The hydroxide method is a method in which a hydroxylating agent (hydroxide ion) and a target metal are reacted and precipitated as a metal hydroxide having low solubility. As the hydroxylating agent as the insolubilizing agent, sodium hydroxide, sodium carbonate, calcium hydroxide, magnesium hydroxide or the like is used. Since the amount of sludge generation is reduced, the hydroxide method using sodium hydroxide is more preferable.
On the other hand, the sulfide method is a method in which a sulfiding agent (sulfide ion) and a target metal are reacted and precipitated as a metal sulfide having low solubility. As the sulfurizing agent as the insolubilizing agent, sodium sulfide, hydrogen sulfide and the like are used.
また、これらの不溶化剤は溶剤に溶解した溶液として用いることもできる。その場合、取り扱い性及び入手容易性の観点から、水溶液を用いることが好ましい。特に不溶化剤として水酸化ナトリウム、及び/又は水酸化ナトリウム水溶液を用いることが好ましい。
不溶化剤を溶液として用いる際の濃度は、不溶化剤溶液を排水に作用させた際に所望の排水中濃度に調整できる濃度であればよい。
不溶化剤を作用させるタイミングとしては、処理する排水の量にもよるが、通常室温若しくは外気温下、酸化剤を作用させた排水に共沈剤を作用させ、撹拌等により混合し、0.1〜50時間、好ましくは0.2〜30時間、より好ましくは0.5〜10時間程度放置した後、不溶化剤を作用させてもよい。These insolubilizers can also be used as a solution dissolved in a solvent. In that case, it is preferable to use an aqueous solution from the viewpoints of handleability and availability. In particular, sodium hydroxide and / or sodium hydroxide aqueous solution is preferably used as the insolubilizing agent.
The concentration when the insolubilizing agent is used as a solution may be a concentration that can be adjusted to a desired concentration in wastewater when the insolubilizing agent solution is allowed to act on the wastewater.
The timing at which the insolubilizing agent is allowed to act depends on the amount of wastewater to be treated, but usually the coprecipitation agent is allowed to act on wastewater that has been treated with an oxidizing agent at room temperature or outside temperature, and is mixed by stirring or the like. After leaving for about 50 hours, preferably 0.2 to 30 hours, more preferably about 0.5 to 10 hours, an insolubilizing agent may be allowed to act.
不溶化剤は、不溶化剤を作用させる不溶化槽において作用させることができる。排水中の重金属(例えば、亜鉛及び銅)を不溶化する不溶化槽は、排水を貯留できるものであれば特に限定されないが、排水、酸化剤、共沈剤及び不溶化剤によって劣化しにくいものが好ましい。不溶化槽への不溶化剤の添加手段としては、固体として若しくは溶液等の液体混合物として不溶化剤が添加できるものであれば、特に限定されない。
不溶化槽は、排水のpH調整工程を行うためのpH調整手段を含んでいてもよい。pH調整手段は、酸又はアルカリを、固体として若しくは溶液等の液体混合物として添加して、不溶化槽内の排水のpHを、所望のpHに調整できるものであればよく、pH計と、酸添加装置及びアルカリ添加装置とを備えた手段等が挙げられる。pH調整手段により槽内のpHが調整される際、重金属が不溶化されてもよい。酸添加装置及びアルカリ添加装置は、不溶化槽へ酸又はアルカリを添加できるものであれば特に限定されないが、酸又はアルカリによって劣化しにくいものが好ましい。また、不溶化槽に酸添加装置及びアルカリ添加装置を備えたpH調整手段が含まれる場合、不溶化槽はさらに酸又はアルカリによって劣化しにくいものが好ましい。pH調整工程で使用される酸としては、例えば、塩酸、硫酸、硝酸、リン酸などの無機酸、シュウ酸、クエン酸、ギ酸、酢酸等の有機酸、又はこれらの混合物等を挙げることができ、これらの中でも、排水処理水質に影響を与えない酸であるという観点から、塩酸若しくは硫酸、又は、これらの混合溶液が好ましく、取り扱い性の観点から硫酸若しくは希硫酸が特に好ましい。また、pH調整工程で使用されるアルカリとしては、例えば、水酸化ナトリウム、水酸化カリウム、水酸化カルシウム、水酸化マグネシウム、炭酸ナトリウム、炭酸水素ナトリウム、炭酸カリウム等を挙げることができ、水酸化ナトリウムが好適に用いられる。なお、pH調整工程を行う前に、処理される排水のpHが所望のpHであれば、pH調整工程は省略することもできる。The insolubilizing agent can be allowed to act in an insolubilizing tank in which the insolubilizing agent acts. The insolubilization tank for insolubilizing heavy metals (for example, zinc and copper) in the wastewater is not particularly limited as long as the wastewater can be stored, but is preferably one that is not easily deteriorated by the wastewater, the oxidizing agent, the coprecipitation agent, and the insolubilizing agent. The means for adding the insolubilizing agent to the insolubilizing tank is not particularly limited as long as the insolubilizing agent can be added as a solid or as a liquid mixture such as a solution.
The insolubilization tank may include a pH adjusting means for performing the pH adjusting step of the waste water. The pH adjusting means is not limited as long as it can adjust the pH of the waste water in the insolubilization tank to a desired pH by adding acid or alkali as a solid or a liquid mixture such as a solution. Means equipped with a device and an alkali addition device, and the like. When the pH in the tank is adjusted by the pH adjusting means, heavy metals may be insolubilized. Although an acid addition apparatus and an alkali addition apparatus will not be specifically limited if an acid or an alkali can be added to an insolubilization tank, What is hard to degrade with an acid or an alkali is preferable. Moreover, when the pH adjustment means provided with the acid addition apparatus and the alkali addition apparatus is contained in an insolubilization tank, what is hard to degrade with an acid or an alkali is further preferable. Examples of the acid used in the pH adjustment step include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid, organic acids such as oxalic acid, citric acid, formic acid and acetic acid, or mixtures thereof. Of these, hydrochloric acid or sulfuric acid, or a mixed solution thereof is preferable from the viewpoint of being an acid that does not affect the quality of the wastewater treatment water, and sulfuric acid or dilute sulfuric acid is particularly preferable from the viewpoint of handleability. Examples of the alkali used in the pH adjustment step include sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium carbonate and the like. Are preferably used. In addition, before performing a pH adjustment process, if the pH of the waste_water | drain to process is desired pH, a pH adjustment process can also be abbreviate | omitted.
なお、水酸化物法により、不溶化の操作、及びpH調整工程を兼ねて行うこともできる。水酸化物法によるpHの調整条件としては、排水中のpHが10〜13となることが好ましく、11〜12がより好ましい。
pHの調整条件が下限値以上であれば、排水中からの重金属(例えば、亜鉛及び銅)の除去効率を高くしやすい。また、pHの調整条件が上限値以下であれば、前記重金属の排水中への再溶解を防止することができ、pH調整のための薬剤の使用量が少なく経済的である。In addition, it is also possible to perform the insolubilization operation and the pH adjustment step by the hydroxide method. As conditions for adjusting the pH by the hydroxide method, the pH in the wastewater is preferably from 10 to 13, and more preferably from 11 to 12.
If pH adjustment conditions are more than a lower limit, it will be easy to make the removal efficiency of heavy metals (for example, zinc and copper) from waste water high. Further, if the pH adjustment condition is equal to or lower than the upper limit value, it is possible to prevent the heavy metal from re-dissolving in the waste water, and the amount of the drug used for pH adjustment is small and economical.
<分離工程>
不溶化した重金属(例えば、亜鉛及び銅)を除去するための分離方法としては、膜濾過、遠心分離、ベルトプレス、沈澱池による沈殿等が挙げられる。なかでも、分離方法としては処理の連続性や不溶化した亜鉛及び銅の沈殿性及び粒子径を考慮すると、バッチ式、フィルタープレス、クロスフロー式、浸漬型等の、分離膜による膜濾過が好ましく、クロスフロー式又は浸漬型による濾過がより好ましい。
(濾過膜)
本発明の工程(ii)の分離工程で用いられる分離膜としての濾過膜としては、濾過能を有するものであれば特に限定されないが、中空糸膜、平膜、チューブラ膜、モノリス型膜等が挙げられる。なかでも、容積充填率が高いことから、中空糸膜が好ましい。
濾過膜として中空糸膜を用いる場合、その材質としては、セルロース、ポリオレフィン、ポリスルホン、ポリフッ化ビニリデンジフロライド(PVDF)、ポリ四フッ化エチレン(PTFE)等が挙げられる。なかでも、中空糸膜の材質としては、耐薬品性やpH変化に強い点から、ポリフッ化ビニリデンジフロライド(PVDF)、ポリ四フッ化エチレン(PTFE)が好ましい。
濾過膜としてモノリス型膜を用いる場合は、セラミック製の膜を用いることができる。<Separation process>
Examples of the separation method for removing insolubilized heavy metals (for example, zinc and copper) include membrane filtration, centrifugation, belt press, precipitation by a sedimentation basin, and the like. Among these, as a separation method, considering the continuity of treatment and the precipitation and particle size of insolubilized zinc and copper, membrane filtration using a separation membrane such as a batch type, filter press, cross flow type, immersion type, etc. is preferable. More preferred is cross-flow or immersion filtration.
(Filtration membrane)
The filtration membrane as a separation membrane used in the separation step of the step (ii) of the present invention is not particularly limited as long as it has filtration ability, but a hollow fiber membrane, a flat membrane, a tubular membrane, a monolith type membrane, etc. Can be mentioned. Among these, a hollow fiber membrane is preferable because of its high volume filling rate.
When a hollow fiber membrane is used as the filtration membrane, examples of the material include cellulose, polyolefin, polysulfone, polyvinylidene fluoride difluoride (PVDF), polytetrafluoroethylene (PTFE), and the like. Among these, as the material for the hollow fiber membrane, polyvinylidene difluoride (PVDF) and polytetrafluoroethylene (PTFE) are preferable from the viewpoint of chemical resistance and resistance to pH change.
When a monolithic membrane is used as the filtration membrane, a ceramic membrane can be used.
膜濾過の形態としては、クロスフロー式で行う場合は、膜濾過用の濾過膜を収めた膜モジュールが、例えば、ハウジング内に濾過膜の排水と接触する側である一次側と濾過水透過側である二次側が隔離されるように濾過膜が固定され、ハウジング内における濾過膜の一次側が、排水中の重金属(例えば、亜鉛及び銅)を不溶化する反応槽と循環ラインにより連通していてもよい。また、クロスフロー式による濾過においては、二次側を濾過ポンプ等で減圧吸引し濾過する方式、又は膜モジュール一次側出口と反応槽を接続する循環ライン上に流量調節機構を設け、循環ラインの圧力をコントロールすることにより、一次側と二次側に圧力差を生じさせ、濾過する方式を用いてもよい。
浸漬型で行う場合は、これら膜濾過用の濾過膜を収めた膜モジュールが、不溶化槽に直接浸漬された状態で、膜濾過を行える装置であってもよい。
さらに、膜モジュールとしては、濾過膜の下方に、膜面洗浄用の曝気手段を設けたものを用いてもよい。前記曝気手段としては、公知のものを採用できる。As a form of membrane filtration, when the cross flow method is used, a membrane module containing a membrane for membrane filtration is, for example, a primary side that is in contact with the drainage of the filtration membrane in a housing and a filtrate water permeation side. The filtration membrane is fixed so that the secondary side is isolated, and the primary side of the filtration membrane in the housing is communicated with a reaction tank for insolubilizing heavy metals (for example, zinc and copper) in the wastewater by a circulation line. Good. Moreover, in the filtration by the cross flow method, the flow rate adjustment mechanism is provided on the circulation line connecting the outlet side of the membrane module and the reaction tank, or the secondary side is suctioned and filtered by a filtration pump or the like. By controlling the pressure, a pressure difference may be generated between the primary side and the secondary side, and filtration may be used.
In the case of performing the immersion type, a device that can perform membrane filtration in a state where the membrane module containing the membrane for membrane filtration is directly immersed in the insolubilization tank may be used.
Further, as the membrane module, a membrane module provided with aeration means for cleaning the membrane surface below the filtration membrane may be used. A well-known thing can be employ | adopted as said aeration means.
濾過膜に形成される微細孔の平均孔径は、0.01〜1.0μmが好ましく、0.05〜0.5μmがより好ましい。微細孔の平均孔径が下限値以上であれば、膜濾過に要する圧力を小さくしやすく、金属凝集物の濃縮効率を高くしやすい。微細孔の平均孔径が上限値以下であれば、金属凝集物の濾液への漏出を抑制しやすい。
排水から重金属を除去する分離工程は、不溶化した重金属を除去する分離装置において行うことができる。分離装置としては、不溶化した重金属を排水から分離する濾過膜等の分離膜を有することが好ましく、従って、分離装置における重金属の除去方法は膜分離であることが好ましい。The average pore diameter of the micropores formed in the filtration membrane is preferably 0.01 to 1.0 μm, more preferably 0.05 to 0.5 μm. If the average pore diameter of the micropores is equal to or greater than the lower limit, the pressure required for membrane filtration can be easily reduced, and the concentration efficiency of metal aggregates can be easily increased. If the average pore diameter of the micropores is not more than the upper limit value, it is easy to suppress leakage of the metal aggregate into the filtrate.
The separation step of removing heavy metals from the waste water can be performed in a separation apparatus that removes insolubilized heavy metals. As the separation device, it is preferable to have a separation membrane such as a filtration membrane for separating insoluble heavy metals from the waste water. Therefore, the method for removing heavy metals in the separation device is preferably membrane separation.
膜濾過により濾過された処理水は、必要に応じてさらに有機物や窒素分等の水質汚濁物質の除去が行われてもよい。また、pHが調整されて河川等に放流されてもよい。 The treated water filtered by membrane filtration may be further subjected to removal of water pollutants such as organic matter and nitrogen as necessary. Further, the pH may be adjusted and discharged into a river or the like.
<処理装置>
本発明の排水処理装置は、(1)酸化剤を作用させる前記酸化槽、(2)共沈剤を作用させる前記共沈槽、(3)重金属を不溶化させる前記不溶化槽、並びに、(4)不溶化した重金属を除去する前記分離装置を含む。これらの槽及び装置はそれぞれ個別の槽及び装置としてもよいが、2つ以上の槽又は装置が一体となった態様でもよい。「2つ以上の槽又は装置が一体となった」とは、例えば、酸化槽において排水に酸化剤を作用させた後、その排水を別途用意された共沈槽に移してから共沈剤を作用させるのではなく、酸化槽において排水に酸化剤を作用させた後、その槽内でさらに共沈剤を作用させるというような態様を意味する。即ち、排水に対して、それぞれの槽及び装置において行われる操作の後、別途用意された、その次の操作が行われる槽又は装置に排水を移すことなく、当該次の操作を同一の槽又は装置内で行うことを意味する。つまり、同一の槽が、酸化剤や共沈剤の作用機能等の複数の機能を有することを意味する。具体的な態様としては、酸化槽と共沈槽における操作が単独の槽内で行われる態様;酸化槽、共沈槽、不溶化槽における操作が単独の槽内で行われる態様;酸化槽、共沈槽、不溶化槽、分離装置における操作が単独の槽内で行われる態様を挙げることができる。中でも、処理設備がコンパクト化でき、経済的であることから、分離装置における操作以外を単独の槽内で行い、分離工程を分離装置で行う態様;あるいは、酸化槽、共沈槽、不溶化槽、分離装置におけるすべての操作が単独の槽内で行われる態様が好ましい。<Processing device>
The waste water treatment apparatus of the present invention includes (1) the oxidation tank in which an oxidizing agent is applied, (2) the coprecipitation tank in which a coprecipitation agent is applied, (3) the insolubilization tank in which heavy metals are insolubilized, and (4) The separation device for removing insoluble heavy metals is included. These tanks and devices may be separate tanks and devices, respectively, but two or more tanks or devices may be integrated. “Two or more tanks or devices are integrated” means, for example, that an oxidant is allowed to act on wastewater in an oxidation tank, and then the wastewater is transferred to a separately prepared coprecipitation tank and then the coprecipitate is added. Instead of acting, it means an embodiment in which an oxidizing agent is allowed to act on waste water in an oxidizing tank, and then a coprecipitation agent is further allowed to act in the tank. That is, after the operation performed in each tank and apparatus for the drainage, the next operation is performed in the same tank or without separately transferring the drainage to the tank or apparatus in which the next operation is performed. Means to be done in the device. That is, it means that the same tank has a plurality of functions such as the function of an oxidizing agent and a coprecipitation agent. As a specific aspect, an operation in the oxidation tank and the coprecipitation tank is performed in a single tank; an aspect in which the operation in the oxidation tank, the coprecipitation tank, and the insolubilization tank is performed in a single tank; The mode in which operation in a settling tank, an insolubilization tank, and a separation apparatus is performed in a single tank can be mentioned. Among them, since the processing equipment can be made compact and economical, an aspect in which operations other than the operation in the separation apparatus are performed in a single tank and the separation step is performed in the separation apparatus; or an oxidation tank, a coprecipitation tank, an insolubilization tank, An embodiment in which all operations in the separation apparatus are performed in a single tank is preferred.
以上説明した本発明は、排水、特に重金属含有排水、とりわけ亜鉛及び銅を含有する排水中から、重金属(特に、亜鉛及び銅)を除去する排水処理方法、及び排水処理装置である。これらにより、前記排水中から、前記重金属を同時に処理することができる。また、排水中の重金属を単独の反応槽内で同時に不溶化し除去すれば、処理設備がコンパクト化でき、経済的である。 The present invention described above is a wastewater treatment method and a wastewater treatment apparatus for removing heavy metals (particularly zinc and copper) from wastewater, particularly heavy metal-containing wastewater, particularly wastewater containing zinc and copper. By these, the said heavy metal can be processed simultaneously from the said waste_water | drain. Also, if heavy metals in the waste water are simultaneously insolubilized and removed in a single reaction tank, the treatment equipment can be made compact and economical.
本発明の処理対象となる排水は、例えば、めっき工場等の金属表面処理工場などから発生しためっき排水を挙げることができ、重金属、及び重金属と配位結合して金属錯体を形成する化合物(以下、「錯体形成化合物」という。)を含むものである。
一方、錯体形成化合物は、重金属のいずれかと配位結合して、重金属原子を中心とする金属錯体を形成する化合物である。錯体形成化合物の例としては、クエン酸、グルコン酸、シュウ酸、酒石酸、コハク酸、シアンおよびこれらの塩等の酸性洗浄成分;EDTA、エチレンジアミン、トリエタノールアミン、アンモニア(アンモニウム塩を含む)等のアミン類などが挙げられる。なお、金属錯体にはキレート錯体も含まれることから、錯体形成化合物には、酒石酸やEDTAなどのキレート剤も当然に該当する。
なお、排水中には、重金属及び錯体形成化合物の他に、洗浄成分や、pH調整成分として界面活性剤、錯体形成化合物以外のルイス酸などが含まれていてもよい。Examples of the wastewater to be treated according to the present invention include plating wastewater generated from a metal surface treatment plant such as a plating plant, etc., and a heavy metal and a compound that forms a metal complex by coordination with a heavy metal (hereinafter referred to as a metal complex). , "Complex forming compound").
On the other hand, a complex-forming compound is a compound that forms a metal complex centered on a heavy metal atom by coordination with any of heavy metals. Examples of complex-forming compounds include acidic cleaning components such as citric acid, gluconic acid, oxalic acid, tartaric acid, succinic acid, cyanide and salts thereof; EDTA, ethylenediamine, triethanolamine, ammonia (including ammonium salts), etc. Examples include amines. In addition, since a chelate complex is also contained in a metal complex, chelating agents, such as tartaric acid and EDTA, naturally correspond to a complex formation compound.
In addition to the heavy metal and the complex-forming compound, the waste water may contain a surfactant, a Lewis acid other than the complex-forming compound, as a cleaning component, and a pH adjusting component.
以下、実施例によって本発明を詳細に説明するが、本発明は以下の記載によっては限定されない。
[亜鉛濃度の測定]
亜鉛濃度は、JIS K 0102−53.3に従い、ICP発光分光分析法により測定した。
[銅濃度の測定]
銅濃度は、JIS K 0102−52.4に従い、ICP発光分光分析法により測定した。EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by the following description.
[Measurement of zinc concentration]
The zinc concentration was measured by ICP emission spectroscopic analysis according to JIS K 0102-53.3.
[Measurement of copper concentration]
The copper concentration was measured by ICP emission spectroscopic analysis according to JIS K 0102-52.4.
[実施例1]
排水中の亜鉛濃度、銅濃度、pHがそれぞれ、160mg/L、4.7mg/L、3.4である、工場排水について排水処理を行った。
前記工場排水に対し、12%次亜塩素酸ナトリウム水溶液を1000mg/Lとなるように撹拌しながら添加し、室温にて1時間放置した。次いで、塩化マグネシウムを前記排水に対してマグネシウム濃度が250mg/Lとなるように撹拌しながら添加し、室温で1時間放置した。
その後、前記排水に対して、pHが11になるように水酸化ナトリウム水溶液を撹拌しながら添加し、前記排水の体積が1.2倍となるように超純水を加えた。この時、前記排水中の亜鉛及び銅濃度はそれぞれ、133mg/L、3.9mg/Lとなった。
次いで、pH調整後の前記排水を、孔径0.45μmのナイロン製ディスクフィルター(Membrane Solution社製)により濾過し、濾過液の亜鉛及び銅濃度を測定した。[Example 1]
Wastewater treatment was performed on factory wastewater having zinc concentration, copper concentration, and pH in the wastewater of 160 mg / L, 4.7 mg / L, and 3.4, respectively.
A 12% sodium hypochlorite aqueous solution was added to the factory effluent while stirring at 1000 mg / L and left at room temperature for 1 hour. Next, magnesium chloride was added to the waste water with stirring so that the magnesium concentration was 250 mg / L, and the mixture was allowed to stand at room temperature for 1 hour.
Thereafter, an aqueous sodium hydroxide solution was added to the waste water while stirring so that the pH was 11, and ultrapure water was added so that the volume of the waste water was 1.2 times. At this time, the zinc and copper concentrations in the wastewater were 133 mg / L and 3.9 mg / L, respectively.
Next, the pH-adjusted waste water was filtered through a nylon disc filter (manufactured by Membrane Solution) having a pore diameter of 0.45 μm, and the zinc and copper concentrations of the filtrate were measured.
[実施例2]
pHを12に調整したこと以外は、実施例1と同様にして、濾過液の亜鉛及び銅濃度を測定した。結果を表1に示す。[Example 2]
Except for adjusting the pH to 12, the zinc and copper concentrations of the filtrate were measured in the same manner as in Example 1. The results are shown in Table 1.
[実施例3]
塩化マグネシウムをマグネシウム濃度が125mg/Lとなるように添加したこと、及びpHを12に調整したこと以外は、実施例1と同様にして、濾過液の亜鉛及び銅濃度を測定した。結果を表1に示す。[Example 3]
The zinc and copper concentrations of the filtrate were measured in the same manner as in Example 1 except that magnesium chloride was added so that the magnesium concentration was 125 mg / L, and the pH was adjusted to 12. The results are shown in Table 1.
[実施例4]
次亜塩素酸ナトリウムを500mg/Lとなるように添加したこと以外は、実施例1と同様にして、濾過液の亜鉛及び銅濃度を測定した。結果を表1に示す。[Example 4]
The zinc and copper concentrations of the filtrate were measured in the same manner as in Example 1 except that sodium hypochlorite was added to 500 mg / L. The results are shown in Table 1.
[実施例5]
次亜塩素酸ナトリウムを500mg/Lとなるように添加したこと、及びpHを12に調整したこと以外は、実施例1と同様にして、濾過液の亜鉛及び銅濃度を測定した。結果を表1に示す。[Example 5]
The zinc and copper concentrations of the filtrate were measured in the same manner as in Example 1 except that sodium hypochlorite was added to 500 mg / L and the pH was adjusted to 12. The results are shown in Table 1.
[実施例6]
次亜塩素酸ナトリウムを500mg/Lとなるように添加したこと、塩化マグネシウムをマグネシウム濃度が125mg/Lとなるように添加したこと、及びpHを12に調整したこと以外は、実施例1と同様にして、濾過液の亜鉛及び銅濃度を測定した。結果を表1に示す。[Example 6]
Same as Example 1 except that sodium hypochlorite was added to 500 mg / L, magnesium chloride was added to a magnesium concentration of 125 mg / L, and the pH was adjusted to 12. Then, the concentration of zinc and copper in the filtrate was measured. The results are shown in Table 1.
[比較例1〜5]
表1に示す通り、次亜塩素酸ナトリウムを0〜2000mg/Lの範囲となるように各々添加したこと、塩化マグネシウムが無添加であること、及びpHを10に調整したこと以外は、実施例1と同様にして、濾過液の亜鉛及び銅濃度を測定した。結果を表1に示す。[Comparative Examples 1-5]
As shown in Table 1, Examples were obtained except that sodium hypochlorite was added to a range of 0 to 2000 mg / L, magnesium chloride was not added, and pH was adjusted to 10. As in 1, the zinc and copper concentrations of the filtrate were measured. The results are shown in Table 1.
[比較例6〜9]
次亜塩素酸ナトリウムが無添加であること、塩化マグネシウムをマグネシウム濃度が500mg/Lとなるように添加したこと、及び表1に示す通り、pHを10〜13に調整したこと以外は、実施例1と同様にして、濾過液の亜鉛及び銅濃度を測定した。結果を表1に示す。[Comparative Examples 6-9]
Examples except that sodium hypochlorite was not added, magnesium chloride was added so that the magnesium concentration was 500 mg / L, and the pH was adjusted to 10 to 13 as shown in Table 1. As in 1, the zinc and copper concentrations of the filtrate were measured. The results are shown in Table 1.
[比較例10〜14]
次亜塩素酸ナトリウムが無添加であること、表1に示す通り、塩化マグネシウムをマグネシウム濃度が25〜750mg/Lとなるように添加したこと、及びpHを12に調整したこと以外は、実施例1と同様にして、濾過液の亜鉛及び銅濃度を測定した。結果を表1に示す。[Comparative Examples 10-14]
Example 1 except that sodium hypochlorite was not added, as shown in Table 1, magnesium chloride was added so that the magnesium concentration was 25 to 750 mg / L, and the pH was adjusted to 12. As in 1, the zinc and copper concentrations of the filtrate were measured. The results are shown in Table 1.
表1中の処理水亜鉛濃度及び処理水銅濃度は、日本国水質汚濁防止法及び下水道法に定められている基準(以下、「日本基準」と言う。)、中華人民共和国汚水総合排出基準(GB8978−1996)に定められている一級基準値(以下、「中国基準」と言う。)より、基準値を満たすものをOK、基準値を満たさないものをNGとした。また、総合判定は前記基準値をすべて満たすものをOK、前記基準値の一つでも満たさないものをNGとした。 The treated water zinc concentration and treated water copper concentration in Table 1 are the standards stipulated in the Japan Water Pollution Control Law and the Sewerage Law (hereinafter referred to as “Japan Standards”), the sewage comprehensive discharge standards of the People's Republic of China ( According to the first-class standard value (hereinafter referred to as “Chinese standard”) defined in GB 8978-1996), those satisfying the standard value were determined to be OK, and those not satisfying the standard value were determined to be NG. In addition, the overall judgment was OK when all of the reference values were satisfied, and NG when none of the reference values was satisfied.
酸化剤(本実施例では、次亜塩素酸ナトリウム)及び共沈剤(本実施例では、塩化マグネシウム)を作用させた実施例1〜6は、亜鉛及び銅について、日本基準及び中国基準を同時に満足することができた。さらに、亜鉛及び銅の除去率が総じて90%以上であり、高い除去率を示した。いずれの実施例においても、亜鉛除去率は98.7重量%以上、実施例5を除いて銅除去率は90.5重量%以上であった。実施例5における銅除去率は88.5重量%であった。なお、除去率は、[{(濾過前の工場排水中の亜鉛又は銅濃度)−(濾過液の亜鉛又は銅濃度)}/濾過前の工場排水中の亜鉛又は銅濃度)]×100(重量%)の式より求めた。
これに対し、酸化剤を作用させず、かつ、共沈剤も作用させなかった比較例1は、銅の除去率が10.3重量%と極めて低く、亜鉛及び銅のいずれについても、日本基準及び中国基準を満たすことができなかった。
また、共沈剤を作用させなかった比較例2〜5は、酸化剤の作用量を増やすことで銅についての日本基準及び中国基準を満たしたが、亜鉛については日本基準及び中国基準をいずれも満たすことができなかった。
また、酸化剤を作用させなかった比較例6〜14は、一部、亜鉛及び銅についての日本基準を同時に満たす態様もあったが、より厳しい排水基準を持つ銅についての中国基準を満足するものはなく、工業排水中に含まれる銅の除去率が23.1重量%〜53.8重量%と、極めて低かった。
したがって、本発明により、簡便、かつ、高い効率で重金属である亜鉛及び銅を同時に除去することが可能であることが示された。In Examples 1 to 6 in which an oxidizing agent (in this example, sodium hypochlorite) and a coprecipitation agent (in this example, magnesium chloride) were allowed to act, both Japanese and Chinese standards were simultaneously applied to zinc and copper. I was satisfied. Furthermore, the removal rate of zinc and copper was generally 90% or more, indicating a high removal rate. In all the examples, the zinc removal rate was 98.7% by weight or more, and except for Example 5, the copper removal rate was 90.5% by weight or more. The copper removal rate in Example 5 was 88.5% by weight. The removal rate is [{(Zinc or copper concentration in factory effluent before filtration) − (Zinc or copper concentration in filtrate)} / Zinc or copper concentration in factory effluent before filtration)] × 100 (weight %).
In contrast, Comparative Example 1 in which no oxidizing agent was allowed to act and no coprecipitate was allowed to act was extremely low in copper removal rate of 10.3% by weight. And could not meet the Chinese standards.
In addition, Comparative Examples 2 to 5 in which the coprecipitation agent did not act satisfied the Japanese standard and the Chinese standard for copper by increasing the action amount of the oxidizing agent, but both the Japanese standard and the Chinese standard for zinc. I could not meet.
Moreover, although Comparative Examples 6-14 which did not make an oxidizing agent act also had the aspect which satisfy | filled the Japanese standard about zinc and copper simultaneously, it satisfies the Chinese standard about copper with a severer drainage standard. However, the removal rate of copper contained in industrial wastewater was extremely low, 23.1 wt% to 53.8 wt%.
Therefore, according to the present invention, it has been shown that zinc and copper, which are heavy metals, can be simultaneously and easily removed with high efficiency.
Claims (12)
(i)前記排水に、酸化剤及び、マグネシウム及び/又はこれらの塩である共沈剤を作用させ、前記排水中の亜鉛及び銅を不溶化させる、不溶化工程;及び
(ii)前記工程(i)に付した排水から、膜濾過により前記不溶化した亜鉛及び銅を除去する、分離工程。 Waste water treatment method for removing zinc and copper from waste water containing zinc and copper, including the following steps (i) and (ii):
(I) an insolubilization step in which an oxidizing agent and a coprecipitation agent that is magnesium and / or a salt thereof are allowed to act on the wastewater to insolubilize zinc and copper in the wastewater; and (ii) the step (i) A separation step of removing the insolubilized zinc and copper from the waste water attached to the membrane by membrane filtration .
Applications Claiming Priority (3)
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JP2014036853 | 2014-02-27 | ||
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PCT/JP2015/054579 WO2015129541A1 (en) | 2014-02-27 | 2015-02-19 | Treatment method and treatment device for waste water containing heavy metal |
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JP7008456B2 (en) * | 2017-09-29 | 2022-01-25 | Dowaテクノロジー株式会社 | Treatment method and treatment equipment for the liquid to be treated |
JP2020196000A (en) * | 2019-02-15 | 2020-12-10 | 株式会社片山化学工業研究所 | Treatment method for cyanide-containing wastewater |
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JPS58174286A (en) * | 1982-04-02 | 1983-10-13 | Sanki Eng Co Ltd | Treatment of waste water containing heavy metal complex salt |
JPS6019092A (en) * | 1983-07-13 | 1985-01-31 | Nec Corp | Treatment of waste liquid |
JPS61192386A (en) * | 1985-02-22 | 1986-08-26 | Kurita Water Ind Ltd | Treatment of waste water containing heavy metal complex |
JPH01148389A (en) * | 1987-12-01 | 1989-06-09 | Kurita Water Ind Ltd | Treatment of water containing heavy metal complex |
JPH02157090A (en) * | 1988-12-09 | 1990-06-15 | Kurita Water Ind Ltd | Treatment of heavy metal-containing waste water |
JP2000117268A (en) * | 1998-10-16 | 2000-04-25 | Dowa Mining Co Ltd | Method for removing antimony in waste water |
JP2003136070A (en) * | 2001-10-31 | 2003-05-13 | National Institute Of Advanced Industrial & Technology | Method and agent for treating lead-containing waste water |
JP2010284593A (en) * | 2009-06-11 | 2010-12-24 | Kurita Water Ind Ltd | Method for recovering water and metal from washing wastewater in electroplating |
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JPS58174286A (en) * | 1982-04-02 | 1983-10-13 | Sanki Eng Co Ltd | Treatment of waste water containing heavy metal complex salt |
JPS6019092A (en) * | 1983-07-13 | 1985-01-31 | Nec Corp | Treatment of waste liquid |
JPS61192386A (en) * | 1985-02-22 | 1986-08-26 | Kurita Water Ind Ltd | Treatment of waste water containing heavy metal complex |
JPH01148389A (en) * | 1987-12-01 | 1989-06-09 | Kurita Water Ind Ltd | Treatment of water containing heavy metal complex |
JPH02157090A (en) * | 1988-12-09 | 1990-06-15 | Kurita Water Ind Ltd | Treatment of heavy metal-containing waste water |
JP2000117268A (en) * | 1998-10-16 | 2000-04-25 | Dowa Mining Co Ltd | Method for removing antimony in waste water |
JP2003136070A (en) * | 2001-10-31 | 2003-05-13 | National Institute Of Advanced Industrial & Technology | Method and agent for treating lead-containing waste water |
JP2010284593A (en) * | 2009-06-11 | 2010-12-24 | Kurita Water Ind Ltd | Method for recovering water and metal from washing wastewater in electroplating |
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