JP2007268382A - Method for cleaning contaminated soil - Google Patents
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本発明は、汚染土壌の浄化方法に関し、特に六価クロムおよび／または揮発性有機化合物を含有する汚染土壌において、六価クロムおよび／または揮発性有機化合物等の汚染物質を効率よく浄化することができる汚染土壌の浄化方法に関する。 The present invention relates to a method for purifying contaminated soil, and in particular, in contaminated soil containing hexavalent chromium and / or volatile organic compounds, it is possible to efficiently purify contaminants such as hexavalent chromium and / or volatile organic compounds. The present invention relates to a method for purifying contaminated soil.
従来より、工場やその跡地等、その周辺地域等の土壌には、重金属やトリクロロエチレン等の有機ハロゲン化合物が含有されており、土壌汚染が大きな社会問題となっている。
このような土壌の汚染は、その土地の再利用や土地開発を困難にするとともに、更には、重金属や有機ハロゲン化合物による地下水の汚染も深刻な問題となっている。
そこで、汚染土壌を浄化する方法が種々検討されている。
Conventionally, soils in the surrounding areas such as factories and their former sites contain organic halogen compounds such as heavy metals and trichlorethylene, and soil contamination has become a major social problem.
Such soil contamination makes it difficult to reuse and develop the land, and also contaminates groundwater with heavy metals and organic halogen compounds.
Accordingly, various methods for purifying contaminated soil have been studied.
汚染土壌の処理方法において、無機系還元剤と、有機系増粘剤（ＣＭＣ、ポリアクリルアマイド、アルギン酸、グアガム、ＭＣ、ＨＥＣ）と、水とからなるスラリーを用い、当該スラリーを汚染土壌中に注入し、処理する方法が、例えば特開平８−２８１２４６号公報等に開示されている。
しかし、この公報においては、無機系還元剤と空気との接触を防ぐために有機系増粘剤であるグアガムが混合されているが、スラリー中で無機系還元剤の分離を抑制することができず、均一な組成を得ることが困難であるという問題点を有している。
In the method for treating contaminated soil, a slurry comprising an inorganic reducing agent, an organic thickener (CMC, polyacrylamide, alginic acid, guar gum, MC, HEC), and water is used. A method of injecting and processing is disclosed in, for example, Japanese Patent Laid-Open No. 8-281246.
However, in this publication, guar gum which is an organic thickener is mixed to prevent contact between the inorganic reducing agent and air, but separation of the inorganic reducing agent cannot be suppressed in the slurry. Therefore, it is difficult to obtain a uniform composition.
一方、比重の大きな金属粉である無機系還元剤の土壌注入材スラリー中での材料分離を抑制するために、前記有機系増粘剤を単独で多量に使用して、スラリー粘性を確保した場合には、有機系増粘剤の急激な増粘作用により、金属粉を均一に混合することができず、ムラのあるスラリーとなってしまう。
更に、グアガムは、有機物であるため、地下水中の有機物量が増大し、ＢＯＤが上昇する可能性がある。
On the other hand, in order to suppress material separation in the soil injection material slurry of the inorganic reducing agent, which is a metal powder having a large specific gravity, when a large amount of the organic thickener is used alone to ensure slurry viscosity However, due to the rapid thickening action of the organic thickener, the metal powder cannot be mixed uniformly, resulting in uneven slurry.
Furthermore, since guar gum is an organic substance, the amount of organic substances in groundwater increases, and BOD may increase.
また、前記したような有機系増粘剤を用いず、例えばスメクタイト系粘土鉱物であるモンモリロナイトを含むベントナイトを増粘剤とし、還元剤と水とからなるスラリーを用い、汚染土壌中に当該スラリーを注入して汚染土壌を処理する方法が、現実に実施されている。
しかし、ベントナイトを用いた場合、比重の重い金属粉がスラリー中で分離することを抑制するスラリー粘度を得るためには、ベントナイトの添加量が多くなり過ぎ、初期のスラリー粘度が高くなり、金属粉を均一に混合することができず、ムラのあるスラリーとなってしまう。
特開２００５−２００２６２号公報（特許文献１）には、鉄粉スラリーの材料分離性を防ぐためベントナイトを混合しているが、土壌浄化処理後のセメント等による地盤固化の際に強度発現を妨害してしまい、浄化後の土地の用途範囲を狭めてしまうという問題がある。
Also, without using an organic thickener as described above, for example, a bentonite containing montmorillonite, which is a smectite clay mineral, is used as a thickener, and a slurry composed of a reducing agent and water is used. A method of injecting and treating contaminated soil is actually implemented.
However, when bentonite is used, in order to obtain a slurry viscosity that suppresses separation of heavy metal powder in the slurry in the slurry, the amount of bentonite added is excessively increased, and the initial slurry viscosity is increased. Cannot be mixed uniformly, resulting in an uneven slurry.
Japanese Patent Laid-Open No. 2005-200262 (Patent Document 1) contains bentonite to prevent the separability of iron powder slurry, but it interferes with the strength development when the soil is solidified with cement after soil purification treatment. Therefore, there is a problem that the range of use of the land after purification is narrowed.
また、特開２００３−１２６８３８号公報（特許文献２）や特開２００４−２０２３４９号公報（特許文献３）には、汚染土壌の浄化方法が開示されているが、土壌中の微生物を活性化するために栄養剤を注入する方法であり、この方法では、目的外の微生物も活性化して弊害が起こる可能性がある。
更に、特開２００５−３１３１２３号公報（特許文献４）には、過酸化水素水と鉄イオンとから生成される活性分子が汚染物質を直接分解することが記載されているが、有毒な過酸化水素水が地下水へ流出するおそれがある。
Moreover, although the purification method of contaminated soil is disclosed by Unexamined-Japanese-Patent No. 2003-126838 (patent document 2) and Unexamined-Japanese-Patent No. 2004-202349 (patent document 3), the microorganisms in soil are activated. Therefore, it is a method of injecting a nutrient, and in this method, undesired microorganisms may be activated to cause harmful effects.
Furthermore, Japanese Patent Application Laid-Open No. 2005-313123 (Patent Document 4) describes that active molecules generated from hydrogen peroxide solution and iron ions directly decompose pollutants. Hydrogen water may flow into groundwater.
他の汚染土壌処理方法としては、汚染土壌を掘削し、地上にてパドル（二軸）ミキサーやコンクリートミキサー、自走式土壌処理機械などによって汚染土壌と還元剤（金属粉等）および砂・礫または酸化剤を強制撹拌しながら混合し、混合処理土を原位置へ戻すという、撹拌混合工法が提案されている（特開２００３−４７９７８号公報（特許文献５）等）。
また、原位置撹拌混合工法として、汚染土壌中に金属鉄粉を装入した後、地盤撹拌混合機を用いて汚染土壌と金属鉄粉とを混合撹拌して処理を行う方法が提案されている（特開２００３−１１２１５８号公報）。
また更に、比重の大きな金属粉を圧縮空気を用いて汚染土壌中に圧送し、混合撹拌して汚染土壌を浄化する方法も提案されている（特開２００２−３２６０８０号公報（特許文献６）等）。
Other methods for treating contaminated soil include excavating contaminated soil and using a paddle (biaxial) mixer, concrete mixer, self-propelled soil treatment machine, etc. on the ground to contaminate soil, reducing agent (metal powder, etc.), sand and gravel. Alternatively, an agitation and mixing method has been proposed in which the oxidant is mixed while forcibly agitating and the mixed soil is returned to the original position (Japanese Patent Laid-Open No. 2003-47978 (Patent Document 5) and the like).
In addition, as an in-situ agitation mixing method, a method is proposed in which metal iron powder is charged into the contaminated soil, and then the contaminated soil and metal iron powder are mixed and agitated using a ground agitation mixer. (Unexamined-Japanese-Patent No. 2003-112158).
Furthermore, a method for purifying contaminated soil by pumping metal powder having a large specific gravity into the contaminated soil using compressed air and mixing and stirring the same has been proposed (Japanese Patent Laid-Open No. 2002-326080 (Patent Document 6), etc.) ).
しかし、汚染土壌と還元剤（金属粉）との粉体添加による混合処理を行う場合、プラント混合処理や原位置処理における表層部分の処理では、汚染土壌（地盤）に直接還元剤（金属粉）を散布し混合撹拌することができる一方、深層部分の混合処理では、先に汚染地盤中に還元剤（金属粉）を装入する工程と、装入した還元剤と汚染地盤とを混合撹拌する工程の２工程を行うため、工期、施工コストが極めて高くなってしまう。 However, when mixing processing by adding powder of contaminated soil and reducing agent (metal powder), the surface layer part processing in plant mixing processing or in-situ processing directly reduces the reducing agent (metal powder) to the contaminated soil (ground). While mixing and stirring can be performed, in the mixing treatment of the deep layer part, the step of charging the reducing agent (metal powder) into the contaminated ground first, and the charged reducing agent and the contaminated ground are mixed and stirred. Since the two steps of the process are performed, the construction period and the construction cost become extremely high.
また、還元剤（金属粉）を圧縮空気を用いて汚染地盤中に圧送する場合、金属粉の摩擦による発熱や静電気等による粉塵爆発の危険性があり、施工安全上も問題があり、空気圧送のためのプラントや施工機械は特殊なものとなり、施工コストも高額なものとなるという問題点を有していた。
本発明の目的は、上記従来の問題点を解決し、粘性を上昇させて金属粉の分離を抑制し、スラリー中の金属粉が均一に土壌に混合できるようにすることで、土壌中の六価クロムや有機ハロゲン系化合物等の汚染物質を有効に浄化することができる、汚染土壌の浄化方法を提供することである。 The object of the present invention is to solve the above-mentioned conventional problems, increase the viscosity to suppress the separation of the metal powder, and allow the metal powder in the slurry to be uniformly mixed with the soil. It is an object of the present invention to provide a method for purifying contaminated soil, which can effectively purify pollutants such as valent chromium and organic halogen compounds.
本発明者らは、特定の粘土鉱物を還元剤である金属、特に鉄粉と組み合わせて得られたスラリーを用いることで、汚染土壌中の六価クロム等の重金属や有機ハロゲン系化合物等の汚染物質を有効に浄化することができることを見出し、本発明を完成した。
すなわち本発明の請求項１記載の汚染土壌の浄化方法は、六価クロムおよび／または揮発性有機化合物を含有する汚染土壌に、鉄粉とセピオライトとを添加混合することを特徴とする。
請求項２記載の汚染土壌の浄化方法は、請求項１記載の汚染土壌の浄化方法において、水とセピオライトとを撹拌混練する工程と、次いで前記工程で得られた材料に鉄粉を添加混合してスラリーを調製する工程と、得られたスラリーを六価クロムおよび／または揮発性有機化合物を含有する汚染土壌中に注入する工程と、スラリーが注入された汚染土壌を撹拌混合する工程とを備えることを特徴とする
By using a slurry obtained by combining a specific clay mineral with a metal as a reducing agent, particularly iron powder, the present inventors can contaminate heavy metals such as hexavalent chromium and organic halogen compounds in contaminated soil. The present inventors have found that a substance can be effectively purified and completed the present invention.
That is, the method for purifying contaminated soil according to claim 1 of the present invention is characterized in that iron powder and sepiolite are added to and mixed with contaminated soil containing hexavalent chromium and / or volatile organic compounds.
The method for purifying contaminated soil according to claim 2 is the method for purifying contaminated soil according to claim 1, wherein the step of stirring and kneading water and sepiolite is added, and then iron powder is added to and mixed with the material obtained in the step. Preparing the slurry, injecting the obtained slurry into the contaminated soil containing hexavalent chromium and / or volatile organic compounds, and stirring and mixing the contaminated soil into which the slurry has been injected. It is characterized by
請求項３記載の汚染土壌の浄化方法は、請求項１または２記載の汚染土壌の浄化方法において、鉄粉とセピオライトは、質量比で、１：１〜１：３の配合割合とすることを特徴とする。
更に請求項４記載の汚染土壌の浄化方法は、請求項２または３記載の汚染土壌の浄化方法において、水／セピオライト比は、質量比で８〜１６であることを特徴とする。
The method for purifying contaminated soil according to claim 3 is the method for purifying contaminated soil according to claim 1 or 2, wherein the iron powder and sepiolite have a mass ratio of 1: 1 to 1: 3. Features.
Furthermore, the method for purifying contaminated soil according to claim 4 is the method for purifying contaminated soil according to claim 2 or 3, wherein the water / sepiolite ratio is 8 to 16 in terms of mass ratio.
本発明の汚染土壌浄化方法は、特定のスラリー浄化材を用いてこれを汚染土壌中に注入して撹拌混合すると、還元剤である鉄粉等の金属粉と土壌中の六価クロム等の重金属や有機ハロゲン系化合物等の汚染物質とが均一に十分に接触できることにより、汚染物質を効率よく浄化することができる。 When the contaminated soil purification method of the present invention is injected into the contaminated soil using a specific slurry purification material and mixed with stirring, a metal powder such as iron powder as a reducing agent and a heavy metal such as hexavalent chromium in the soil And pollutants such as organic halogen compounds can be contacted uniformly and sufficiently, so that the pollutants can be efficiently purified.
また、前記スラリーにセメント等の水硬性物質を添加することにより、上記効果に加えて、更に汚染土壌中に含まれる重金属類を難溶性物質の生成により固定化したり、水和生成物による置換固溶や表面吸着により固定化したり、及び硬化組織の緻密化により封じ込めたりすることにより、汚染物質を効率よく固化することができるとともに、軟弱化した土壌の強度も確保することができる。 Further, by adding a hydraulic substance such as cement to the slurry, in addition to the above effects, the heavy metals contained in the contaminated soil can be further fixed by the generation of a hardly soluble substance, or can be replaced with a hydrated product. By fixing by dissolution or surface adsorption, or by confining by hardening the hardened tissue, it is possible to efficiently solidify the pollutant and to secure the strength of the softened soil.
また、本発明の汚染土壌の浄化方法は、汚染土壌中の六価クロムや有機ハロゲン系化合物等の汚染物質を効率良く浄化することを可能とし、汚染物質を含有する土壌の有効活用を可能にするものである。 In addition, the contaminated soil purification method of the present invention enables efficient purification of contaminants such as hexavalent chromium and organic halogen compounds in the contaminated soil, and enables effective use of the soil containing the contaminant. To do.
本発明を、以下の好適例を用いて説明するがこれらに限定されるものではない。
本発明の汚染土壌の浄化方法は、六価クロムおよび／または揮発性有機化合物を含有する汚染土壌に、金属粉、特に鉄粉とセピオライトとを添加混合する方法である。
特に好適には、本発明の汚染土壌の浄化方法は、水とセピオライトとを撹拌混練する工程と、次いで前記工程で得られた材料に鉄粉を添加混合してスラリーを調製する工程と、得られたスラリーを六価クロムおよび／または揮発性有機化合物を含有する汚染土壌中に注入する工程と、スラリーが注入された汚染土壌を撹拌混合する工程とを備えるものである。
このように、鉄粉とセピオライトとを組み合わせたスラリーを汚染土壌中に注入して混合することにより、鉄粉と空気との接触を妨げ、鉄粉が空気により酸化されることを防止することができ、長期間、土壌中の汚染物質の浄化効果を持続することができる。
The present invention will be described with reference to the following preferred examples, but is not limited thereto.
The method for purifying contaminated soil of the present invention is a method of adding and mixing metal powder, particularly iron powder and sepiolite, to contaminated soil containing hexavalent chromium and / or volatile organic compounds.
Particularly preferably, the method for purifying contaminated soil of the present invention comprises a step of stirring and kneading water and sepiolite, a step of preparing a slurry by adding and mixing iron powder to the material obtained in the above step, and A step of injecting the resulting slurry into contaminated soil containing hexavalent chromium and / or volatile organic compounds, and a step of stirring and mixing the contaminated soil into which the slurry has been injected.
Thus, by injecting and mixing the slurry combining iron powder and sepiolite into the contaminated soil, the contact between the iron powder and air can be prevented, and the iron powder can be prevented from being oxidized by air. It is possible to maintain the purification effect of pollutants in the soil for a long time.
本発明の汚染土壌の浄化方法に用いられる金属粉としては、還元性金属粉であれば任意のものを使用することができ、例えば、鉄粉やマグネシウム粉等が例示でき、特に、鉄が安価で容易に市場で入手でき、セピオライトとの組み合わせにおいて有効に上記効果を発揮することができることから好適に使用されている。
かかる金属粒子の粒径は可能な限り小さい方がよく、それは粒子の反応面積を大きくすることができ、またスラリー中において分離し難くなるからである。
As the metal powder used in the method for purifying contaminated soil of the present invention, any metal powder can be used as long as it is a reducible metal powder. Examples thereof include iron powder and magnesium powder, and particularly, iron is inexpensive. It can be easily obtained on the market and can be effectively used in combination with sepiolite.
The particle size of the metal particles should be as small as possible because the reaction area of the particles can be increased and it is difficult to separate them in the slurry.
本発明の汚染土壌の浄化方法には、セピオライト等のセピオライト族鉱物が用いられる。
セピオライトは、水と鉄粉とを組み合わせて用いた場合に、水と混合されて膨張する。
またセピオライトは、セメント系固化材で地盤改良を行なった場合に、強度発現性にも悪影響を与えない点でも有効に用いることができる。
その混合割合は、特に限定されず、初期のスラリー粘度を抑制し、均一に鉄粉を混合できる時間が経過した後、スラリー粘度が上昇するような割合であれば良いが、スラリー中の水／セピオライト比が、質量比で５〜２０、好適には８〜１６であると、特に前記作用に優れることから望ましい。
Sepiolite group minerals such as sepiolite are used in the method for purifying contaminated soil of the present invention.
Sepiolite is mixed with water and swells when water and iron powder are used in combination.
Sepiolite can also be used effectively in that it does not adversely affect strength development when the ground is improved with a cement-based solidified material.
The mixing ratio is not particularly limited, and may be any ratio that increases the slurry viscosity after the time that the initial slurry viscosity is suppressed and the iron powder can be uniformly mixed has elapsed. It is desirable that the sepiolite ratio is 5 to 20, preferably 8 to 16 in terms of mass ratio, since the above action is particularly excellent.
スラリーを調製する方法としては、水とセピオライトと鉄粉とが均一に混合することができればその調製方法は特に限定されないが、特に好ましくは水とセピオライトとを撹拌混練し、次いで前記工程で得られた混練材料に鉄粉を添加混合することにより調製することが、鉄粉を均一に短時間で混練することができる点から好ましい。 The method for preparing the slurry is not particularly limited as long as water, sepiolite, and iron powder can be uniformly mixed, but particularly preferably, water and sepiolite are stirred and kneaded and then obtained in the above step. It is preferable to prepare by adding and mixing iron powder to the kneaded material because iron powder can be uniformly kneaded in a short time.
スラリー中に含まれるセピオライトと鉄との配合割合は、スラリー中で鉄粉が均一に分散できれば特に限定されないが、好ましくは、その配合割合は、質量比で１：１〜１：３、好ましくは１：１．６〜１：２．４であり、このような配合割合とすることで、特に、混練直後のスラリー粘度を抑制し、添加される金属粉を均一に混練できるとともに、混練後の金属粉の材料分離を抑えることができるという利点が得られる。
また、セピオライトが、鉄粉の周囲を被覆することとなり、空気等に触れても、酸化することなく、土壌中の汚染物質を効率よく還元することができる。
The blending ratio of sepiolite and iron contained in the slurry is not particularly limited as long as the iron powder can be uniformly dispersed in the slurry. Preferably, the blending ratio is 1: 1 to 1: 3, preferably by mass ratio. The ratio is 1: 1.6 to 1: 2.4. By setting the mixing ratio as described above, in particular, the viscosity of the slurry immediately after kneading can be suppressed, and the added metal powder can be uniformly kneaded, and after kneading. The advantage that the material separation of the metal powder can be suppressed is obtained.
Further, sepiolite covers the periphery of the iron powder, and even if it touches air or the like, it can efficiently reduce contaminants in the soil without oxidizing.
また、本発明の汚染土壌の浄化方法に用いるスラリーには、必要に応じて、サリチル酸、安息香酸、安息香酸ナトリウム、ソルビン酸、ソルビン酸ナトリウム、デヒドロ酢酸、デヒドロ酢酸ナトリウム、パラオキシ安息香酸エステル、メチルナフトキノン、有機窒素系化合物、含ハロゲン窒素硫黄系化合物、含窒素環状化合物等の防腐剤を添加して、保存安定性を高めることも可能である。 Further, the slurry used in the method for purifying contaminated soil of the present invention includes, as necessary, salicylic acid, benzoic acid, sodium benzoate, sorbic acid, sodium sorbate, dehydroacetic acid, sodium dehydroacetate, p-hydroxybenzoate ester, methyl Preservatives such as naphthoquinone, organic nitrogen compounds, halogen-containing nitrogen-sulfur compounds, and nitrogen-containing cyclic compounds can be added to enhance storage stability.
更に本発明の方法に用いるスラリーには、必要に応じて、セメント、高炉スラグ、石灰石粉、フライアッシュ、シリカ粉、炭酸カルシウム及び石膏からなる群より選ばれた少なくとも１種の添加材を混合することができる。
これらの添加材を混合することにより、スラリーの単位水量を減少させて、ブリーディングを抑制することができる。
Furthermore, the slurry used in the method of the present invention is mixed with at least one additive selected from the group consisting of cement, blast furnace slag, limestone powder, fly ash, silica powder, calcium carbonate, and gypsum as necessary. be able to.
By mixing these additives, the unit water amount of the slurry can be reduced and bleeding can be suppressed.
本発明の汚染土壌の浄化方法は、上記セピオライトと鉄粉とを含有するスラリーを汚染土壌と混合することにより、汚染土壌中に含まれる重金属類を還元したり有機ハロゲン化合物等の有機物質を分解したりすることができる。
更に、セピオライト及び鉄粉に加えて、上記セメント等の固化材をも含有するスラリーを汚染土壌に混合することで、前記作用に加えて、難溶性物質の生成により固定化したり、水和生成物による置換固溶や表面吸着により固定化したり、及び硬化組織の緻密化により封じ込めたりすることにより、汚染物質を効率よく固化・不溶化することができるとともに、軟弱化した土壌の強度も確保することができる。
In the method for purifying contaminated soil of the present invention, the slurry containing the sepiolite and iron powder is mixed with the contaminated soil to reduce heavy metals contained in the contaminated soil or decompose organic substances such as organic halogen compounds. You can do it.
Furthermore, in addition to sepiolite and iron powder, the slurry containing a solidifying material such as cement is mixed with the contaminated soil, so that in addition to the above action, it is fixed by the generation of a hardly soluble substance, or the hydrated product It is possible to solidify and insolubilize pollutants efficiently and to secure the strength of softened soil by immobilizing by substitution solid solution and surface adsorption by, or by confining by hardening the hardened tissue. it can.
本発明においては、上記スラリーを汚染土壌中に添加混合する工法としては、現場の土壌中にスラリーを注入散布する原位置処理工法や、ニーダー、ブレンダー等の土木機械を用いて土壌を機械的に撹拌混合する掘削処理工法を採用することができる。
以上のような土壌処理を行うことにより、土壌中に含まれる六価クロム、有機ハロゲン化合物、揮発性有機化合物等の汚染物質の浄化を効率よく実施することができる。
汚染物質としては、前記した六価クロムだけではなく、例えば重金属や有機系塩素化合物など、種々の環境的に問題となっている酸化し得る任意の物質が対称となる。
In the present invention, as a method for adding and mixing the slurry into the contaminated soil, the soil is mechanically used by using an in-situ processing method for injecting and dispersing the slurry into the soil at the site, or a civil engineering machine such as a kneader or a blender. An excavation processing method of stirring and mixing can be employed.
By performing the soil treatment as described above, it is possible to efficiently purify contaminants such as hexavalent chromium, organic halogen compounds, and volatile organic compounds contained in the soil.
As the pollutant, not only the hexavalent chromium described above but also various substances that can be oxidized, such as heavy metals and organic chlorine compounds, which are problematic in terms of environment, are symmetrical.
本発明の次の実施例、比較例及び試験例により説明する。
使用材料
以下の実施例及び比較例において、次の原材料を使用した。
鉄粉；商品名；Ｅ−２００ 比重７．１１ 同和鉄粉工業株式会社
増粘材；
グアガム：Ｆ−５０（三菱商事株式会社）
ベントナイト：スーパークレイ（豊順洋行株式会社）
セピオライト：ミラクレＰ−８００Ｖ（近江産業株式会社）
セメント系固化材；タフロック３型（住友大阪セメント株式会社）
混練水；水道水
The following examples, comparative examples and test examples of the present invention will be described.
Materials used The following raw materials were used in the following Examples and Comparative Examples.
Product name; E-200 Specific gravity 7.11 Dowa Iron Powder Industry Co., Ltd. thickener;
Guam gum: F-50 (Mitsubishi Corporation)
Bentonite: Super Clay (Toyoshun Yoko Co., Ltd.)
Sepiolite: Miracle P-800V (Omi Sangyo Co., Ltd.)
Cement-based solidifying material; Tough rock type 3 (Sumitomo Osaka Cement Co., Ltd.)
Kneading water; tap water
実施例１〜２・比較例１〜４
（スラリー）
上記原材料を用いて表１に示す配合割合で、所定量の増粘材と水とを、ミキサーを用いて十分に混練し、次いで所定量の鉄粉を加えて更に十分に混練して、土壌浄化材スラリーを調製した。
実施例及び比較例で添加した増粘材の添加量は、スラリーを調製した後６時間経過後も材料の分離（ブリーディング及び鉄粉の沈降）が生じない配合量であることより、得られたスラリーは金属粉を均一に混練でき、かつ金属粉の分離も起こらないスラリーである。
Examples 1-2 and Comparative Examples 1-4
(slurry)
Using the above-mentioned raw materials, in a blending ratio shown in Table 1, a predetermined amount of thickener and water are sufficiently kneaded using a mixer, then a predetermined amount of iron powder is added and further sufficiently kneaded, and soil A purification material slurry was prepared.
The addition amount of the thickener added in Examples and Comparative Examples was obtained because the amount was not such that separation of materials (bleeding and sedimentation of iron powder) did not occur after 6 hours from the preparation of the slurry. The slurry is a slurry that can uniformly knead metal powder and does not cause separation of the metal powder.
（土壌）
以下の表２に示す２種類の実土壌に、重金属として六価クロム（重クロム酸カリウム）を、揮発性有機化合物（ＶＯＣ）としてＴＣＥ（トリクロロエチレン）を添加した模擬汚染土を作製した。
得られた２種の土壌に対して、クロム（Ｃｒ６＋）とＶＯＣとは環境庁告示第４６号試験により、また有機体炭素（ＴＯＣ）については原位置からの溶出を想定して環境庁告示第１３号試験に準拠して溶出試験を行った。その結果を表２に示す。
(soil)
Simulated contaminated soil was prepared by adding hexavalent chromium (potassium bichromate) as a heavy metal and TCE (trichloroethylene) as a volatile organic compound (VOC) to two kinds of real soils shown in Table 2 below.
Chromium (Cr 6+ ) and VOC for the two types of soils obtained from the Environmental Agency Notification No. 46 test, and for organic carbon (TOC), assuming the elution from the original location, the Environmental Agency Notification The dissolution test was conducted according to the 13th test. The results are shown in Table 2.
（浄化方法）
上記表１に示すように、表２の２種の砂質土又は海成粘土各１ｄｍ３に、表１に示すスラリーを添加し、ミキサー（ＡＣＭ−２０：株式会社愛工舎製作所製）で十分に混練後、掻き落としを行い、更に十分に撹拌混練して、処理土を作製した。
(Purification method)
As shown in Table 1 above, the slurry shown in Table 1 is added to 1 dm 3 each of the two types of sandy soil or marine clay in Table 2, and a mixer (ACM-20: manufactured by Aikosha Seisakusho Co., Ltd.) is sufficient. After kneading, it was scraped off and further sufficiently stirred and kneaded to prepare treated soil.
（試験例１）
該各処理土を７日間２０℃の恒温室で養生し、環境庁告示第４６号試験により溶出させ、六価クロム濃度と、ＶＯＣ濃度とを測定した。
その結果を表３に示す。
但し、溶出液中の六価クロム濃度は、ＪＩＳ Ｋ ０１０２「工業排水試験方法」に準拠して測定した。その評価基準は、環境基準０．０５ｍｇ／ｌ以下を○、基準値超を×として示す。
(Test Example 1)
Each treated soil was cured in a constant temperature room at 20 ° C. for 7 days and eluted by the Environmental Agency Notification No. 46 test, and the hexavalent chromium concentration and the VOC concentration were measured.
The results are shown in Table 3.
However, the hexavalent chromium concentration in the eluate was measured according to JIS K 0102 “Industrial Wastewater Test Method”. The evaluation criteria are indicated by ◯ when the environmental standard is 0.05 mg / l or less and x when the reference value is exceeded.
またＶＯＣは、下記ＧＣ−ＭＳで、トリクロロエチレン濃度を測定した。但し、測定直前にＮａＣｌを３ｇを添加したものを用いた。その評価基準は、トリクロロエチレンの環境基準０．０３ｍｇ／ｌ以下を○、基準値超を×として評価した。
・ＧＣＭＳ測定条件（ヘッドスペース法）
バイアル瓶：２０ｍＬ，恒温槽温度：８０℃
加熱時間：２０分，ループ温度：１３０℃，トランスファーライン温度：１８０℃
カラム：ＨＰ−ＶＯＣ
注入モード：パルスドスプリット注入法，スプリット比：７：１，注入口温度：２００℃
パルス圧：２０ｐｓｉ，キャリアガス流量：２．０ｍＬ／分（コンスタントフローモード），キャリアガス：Ｈｅ
オーブン温度：４０℃（７分）→７℃／分→１８０℃（０分）→１８℃／分→２５０℃（０分）
定量方法：ＶＯＣ混合標準液０，０．００１，０．０１，０．１ｐｐｍの４点検量線により定量
０．１ｐｐｍ〜５ｐｐｍは、ＶＯＣ混合標準液０．１ｐｐｍ，５ｐｐｍの２点検量線で定量
Moreover, VOC measured the trichlorethylene density | concentration by following GC-MS. However, what added 3 g of NaCl immediately before the measurement was used. As the evaluation criteria, the environmental standard 0.03 mg / l or less of trichlorethylene was evaluated as ◯, and the standard value exceeded was evaluated as x.
・ GCMS measurement conditions (headspace method)
Vials: 20 mL, temperature chamber temperature: 80 ° C
Heating time: 20 minutes, loop temperature: 130 ° C, transfer line temperature: 180 ° C
Column: HP-VOC
Injection mode: Pulsed split injection method, split ratio: 7: 1, inlet temperature: 200 ° C
Pulse pressure: 20 psi, carrier gas flow rate: 2.0 mL / min (constant flow mode), carrier gas: He
Oven temperature: 40 ° C (7 minutes) → 7 ° C / minute → 180 ° C (0 minute) → 18 ° C / minute → 250 ° C (0 minute)
Quantitative method: quantified by 4 inspection curve lines of VOC mixed standard solution 0,0.001,0.01,0.1ppm 0.1ppm-5ppm is quantified by 2 inspection curve lines of VOC mixed standard solution 0.1ppm, 5ppm
（試験例２）
試験例１と同様にして調製した７日養生後の各処理土を、環境庁告示第１３号に準拠して溶出させ、ＴＯＣ測定機器（ＴＯＣ−６５０：東レエンジニアリング製）を用いて、該各溶出液のＴＯＣ濃度を測定した。その評価基準は、処理前の各土壌自体の溶出量を１００％とし、１００％以下を○、１００〜１３０％を△、１３０％以上は×として評価した。
その結果を表３に示す。
(Test Example 2)
Each treated soil after curing for 7 days prepared in the same manner as in Test Example 1 was eluted according to Environmental Agency Notification No. 13 and each of the treated soils was prepared using a TOC measuring device (TOC-650: manufactured by Toray Engineering). The TOC concentration of the eluate was measured. The evaluation criteria were evaluated as 100% for the elution amount of each soil itself before treatment, ○ for 100% or less, Δ for 100 to 130%, and × for 130% or more.
The results are shown in Table 3.
（試験例３）
試験例１と同様にして調製した７日養生後の各処理土に対して、固化材（タフロック３型：住友大阪セメント製）を２００ｋｇ／ｍ３添加し、ミキサー（試験例１と同一のもの）を用いて１分間混練後、掻き落としを行い、更に１分間混練した。
次いで、得られた固化材含有処理土を用いて、φ＝５０ｍｍ×高さ１００ｍｍの供試体を作製し、２０℃で養生後、材齢７日の供試体について、圧縮強度試験をＪＩＳ Ａ １２１６「土の一軸圧縮試験方法」に準拠して圧縮強度を測定した。その評価基準は、土壌１ｍ３と固化材２００ｋｇと水３５０ｋｇとを添加した際の強度を１００％として、１００％以上を○、１００％〜７５％を△、７５％以下を×として評価した。但し、砂質土そのものの圧縮強度は１１００ｋＮ／ｍ２、海成粘土そのものの圧縮強度は１６００ｋＮ／ｍ２である。
その結果を表３に示す。
(Test Example 3)
200 kg / m 3 of solidified material (Tough Rock 3 type: manufactured by Sumitomo Osaka Cement) was added to each treated soil after 7 days curing prepared in the same manner as in Test Example 1, and a mixer (same as Test Example 1) ) Was used for 1 minute, scraped off, and further kneaded for 1 minute.
Next, using the obtained solidified material-containing treated soil, a specimen having φ = 50 mm × height of 100 mm was prepared, and after curing at 20 ° C., a compressive strength test was performed on a specimen having a material age of 7 according to JIS A 1216. The compressive strength was measured in accordance with “Soil Uniaxial Compression Test Method”. The evaluation criteria, the intensity upon addition of a solidifying material 200kg water 350kg soil 1 m 3 as 100%, ○ more than 100%, the 100% to 75% △, and rated 75% or less ×. However, the compressive strength of sandy soil itself is 1100 kN / m 2 , and the compressive strength of marine clay itself is 1600 kN / m 2 .
The results are shown in Table 3.
この結果より、実施例では、クロム、ＶＯＣ及びＴＯＣの溶出量も少なく、７日目の圧縮強度も良好であることがわかった。
比較例１では、ＶＯＣの溶出量が高く、また圧縮強度も十分なものではない。
比較例２では、クロム、ＶＯＣ及びＴＯＣの溶出量が高く、７日目の圧縮強度も良好でない。
更に比較例３では、ＶＯＣの溶出量が高く、７日目の圧縮強度も十分ではなく、比較例４では、ＶＯＣ及びＴＯＣの溶出量が高く、７日目の圧縮強度も十分ではないことがわかる。
From these results, it was found that the amount of elution of chromium, VOC and TOC was small and the compressive strength on the seventh day was good in the examples.
In Comparative Example 1, the elution amount of VOC is high and the compressive strength is not sufficient.
In Comparative Example 2, the elution amounts of chromium, VOC and TOC are high, and the compression strength on the seventh day is not good.
Further, in Comparative Example 3, the elution amount of VOC is high and the compression strength on the seventh day is not sufficient, and in Comparative Example 4, the elution amount of VOC and TOC is high and the compression strength on the seventh day is not sufficient. Recognize.
本発明の汚染土壌の浄化方法は、工場、工場跡地等、従来は汚染物質が問題となり有効活用を困難としていた地盤に適用することができ、土地の有効利用が図れることとなる。
The method for purifying contaminated soil according to the present invention can be applied to ground such as factories, factory ruins, and the like, which has conventionally been difficult to effectively utilize due to contaminants, and can effectively use the land.
Claims (4)
4. The method for purifying contaminated soil according to claim 2, wherein the water / sepiolite ratio is 8 to 16 in terms of mass ratio.
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| JP2005255737A (en) * | 2004-03-09 | 2005-09-22 | Sumitomo Osaka Cement Co Ltd | Method for producing heavy metal adsorbent from waste and heavy metal adsorbent obtained by the method |
| JP2006055724A (en) * | 2004-08-19 | 2006-03-02 | Nippon Steel Corp | Method for soil restoration |
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| JP2002206090A (en) * | 2000-11-09 | 2002-07-26 | Matsuda Giken Kogyo Kk | Neutral soil-solidifying agent and method of improving ground and the like, and means for preventing elution of heavy metal |
| JP2003170152A (en) * | 2001-12-04 | 2003-06-17 | Denki Kagaku Kogyo Kk | Reducing agent of hexavalent chromium |
| JP2005200262A (en) * | 2004-01-15 | 2005-07-28 | Mitsui Mining & Smelting Co Ltd | Porous material, its producing method, and method for cleaning soil using porous material |
| JP2005255737A (en) * | 2004-03-09 | 2005-09-22 | Sumitomo Osaka Cement Co Ltd | Method for producing heavy metal adsorbent from waste and heavy metal adsorbent obtained by the method |
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