JP2004305792A

JP2004305792A - Detoxication method for object to be treated contaminated with organic halogen compound

Info

Publication number: JP2004305792A
Application number: JP2003098530A
Authority: JP
Inventors: Toshiki Shimizu; 要樹清水; Yasuyuki Nagai; 康行長井
Original assignee: Tosoh Corp
Current assignee: Tosoh Corp
Priority date: 2003-04-01
Filing date: 2003-04-01
Publication date: 2004-11-04
Anticipated expiration: 2023-04-01
Also published as: JP4127102B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treating method capable of decomposing organic halogen compounds in soil, industrial waste, polluted sludge, sludge, waste water and ground water in a short period of time into the environmental criteria or less and detoxifying the compounds without producing harmful by-product. <P>SOLUTION: In the method for detoxifying an object to be treated contaminated with organic halogen compounds, a metallic treating agent comprising alloy powder which is produced by subjecting a mixture containing 0.01-2 pts.wt. Ni powder based on 100 pts.wt. Fe powder to the treatment according to the mechanical alloying method and an oxidant are added to the object to be treated and are mixed. Thereby, the object to be treated contaminated with the organic halogen compounds is detoxified. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、有機ハロゲン化合物で汚染された土壌、産業廃棄物、汚泥、スラッジ、排水、地下水等の被処理物に対する無害化処理方法に関するものである。
【０００２】
【従来の技術】
世界各地でＴＣＥ（トリクロロエチレン）、ＰＣＥ（テトラクロロエチレン）、ジクロロメタン、ＰＣＢ（ポリ塩化ビフェニル）及びダイオキシン類等の有機ハロゲン化合物による環境汚染問題が顕在化し大きな問題となっている。
【０００３】
これらの問題に対し、特に揮発性有機ハロゲン化合物（以降ＶＯＣと略記する）により汚染された土壌、排水、地下水等に対する無害化用処理剤およびその処理方法が検討され、いくつかの技術報告や特許出願がされている。
【０００４】
１）汚染排水、地下水等の場合、真空抽出法や揚水曝気法等が知られているが、地上への引き上げ装置、さらに引き上げた前記汚染物質の吸着設備、活性炭吸着剤の再生処理や発生廃棄物の処理が必要となり、施工全体としては高コストの処理方法となる。また、無害化には数年を要し、完全除去は難しい技術である。近年、金属系処理剤により汚染物質を還元脱ハロゲン化する無害化処理法が報告され、従来法に比べ低コスト化が図れるとしている。鉄系処理剤により無害化する方法が提案されている（例えば、特許文献１参照。）が、汚染排水、地下水中に水素等を供給し溶存酸素の除去が必要であり、実汚染地下水への適応は困難と思われる。別の方法として地下水域に鉄系処理剤を混合する透過壁工法（例えば、特許文献２〜３参照。）が提案されているが、この方法も処理時間が長く、また完全に浄化できない。一方、酸化による無害化処理法が提案されている（例えば、特許文献４〜６参照。）が、高濃度の過マンガン酸塩を添加することから２次汚染が心配され、また適正な酸化剤の添加量を制御することが操作上、複雑であり無害化処理は困難と思われる。
２）汚染土壌、スラッジ、汚泥等の処理法としては封じ込め処理が主であるが、掘削土壌または直接土壌中に加熱用電極を挿入し加熱処理する熱脱着法および熱分解法も知られている。この方法は大掛かりな加熱装置が必要である。また電極近傍は熱分解されるが、その他はＶＯＣを中心に地上に揮散するだけで根本的な処理法では無く、処理後の土壌は熱により固化し、微生物はほとんど死滅するため再利用の点でも採用は難しい。微生物を経由した還元物質により無害化処理するバイオレメデイエ−ション法があるが、無害化には長時間必要であり、しかも全種類の土壌に対応できず完全な無害化は不可能である。化学的処理として、汚染土壌に鉄系処理剤を添加した例としては鉄粉を混合した連続浄化壁を形成する方法（例えば、特許文献７参照。）は、掘削土壌と鉄系処理剤を混合し地上にパイル（山）状に積み上げ静置処理する方法が提案されている（例えば、特許文献８参照。）が、浄化に長時間が必要である。一方、酸化処理法として、鉄粉に過酸化水素水または過硫酸塩を添加する方法が提案されている（例えば、特許文献９〜１０参照。）が、やはり浄化に長時間が必要である。別の方法として、金属鉄、硫酸鉄、塩化鉄の１種と酸化剤を添加する処理法が提案されている（例えば、特許文献１１）が、特殊な混合法によりはじめて分解反応が進むことから、鉄系処理剤の改良が望まれる。
【０００５】
【特許文献１】
特公平２−４９７９８号公報（特許請求の範囲）
【特許文献２】
特許第３２１６０１４号公報（特許請求の範囲）
【特許文献３】
特開２００２−７９２０６号公報（特許請求の範囲）
【特許文献４】
特開２０００−２１０６８３号公報（特許請求の範囲）
【特許文献５】
特開２００２−３０１４８６号公報（特許請求の範囲）
【特許文献６】
特開２００２−３３１２８０号公報（特許請求の範囲）
【特許文献７】
特開２００１−３２１７６２号公報（特許請求の範囲）
【特許文献８】
特開２００１−００５７７号公報（特許請求の範囲）
【特許文献９】
特開２００２−１１９９７７号公報（特許請求の範囲）
【特許文献１０】
特開２００２−３０７０４９号公報（特許請求の範囲）
【特許文献１１】
特開２００２−３２６０８０号公報（特許請求の範囲）
【０００６】
【発明が解決しようとする課題】
以上述べたように有機ハロゲン化合物で汚染された土壌、産業廃棄物、汚泥、スラッジ、排水、地下水等に対する従来の処理法は汚染物質を積極的に分解して無害化処理する技術ではないこと、処理期間が１０〜２０年と長いこと、コスト高であること、処理法が複雑であること、環境負荷が大きいことなどの課題を抱えている。
【０００７】
本発明の目的は、被処理物中の有機ハロゲン化合物に適用されている環境基準を短期間にクリアでき、処理法が簡便でコストが低く、環境負荷の小さな有機ハロゲン化合物で汚染された土壌、産業廃棄物、汚泥、スラッジ、排水、地下水等の被処理物に対する無害化処理方法を提供するものである。
【０００８】
【課題を解決するための手段】
本発明者は、前記目的を達成するために、高分解性を有する金属系処理剤すなわちメカニカルアロイング（以降ＭＡと略記する）法により得たＦｅ−Ｎｉ合金および酸化剤の組み合わせによる処理方法について検討した。
【０００９】
即ち、Ｆｅ粉末１００重量部に対しＮｉ粉末０．０１〜２重量部からなる混合物をＭＡ法により得た合金粉末から成る金属系処理剤及び酸化剤を被処理物に添加、混合することを特徴とする処理方法を提供するもので、本発明の処理剤および処理方法によれば短期間において汚染有機ハロゲン化合物濃度を環境基準値以下にすることができる。更に、難分解性と言われるＣｉｓ−ＤＣＥ（ｃｉｓ−１，２−ジクロロエチレン）、ＭＣ（メチルクロロホルム、または１，１，１−トリクロロエタン）、ＰＣＥをも分解することができる。
【００１０】
以下に、本発明について詳細に説明をする。
【００１１】
本発明の無害化処理方法において、無害化処理する被処理物は、有機ハロゲン化合物で汚染されたものである。有機ハロゲン化合物の例としては、ジクロロメタン、四塩化炭素、クロロホルム、１，２−ジクロロエタン、１，１−ＤＣＥ（１，１−ジクロロエチレン）、Ｃｉｓ−ＤＣＥ、Ｔｒａｎｓ−ＤＣＥ（ｔｒａｎｓ−１，２−ジクロロエチレン）、ＭＣ、１，１，２−トリクロロエタン、ＴＣＥ、ＰＣＥ、１，３−ジクロロプロペン等の有機塩素系化合物、またはこれらの有機臭素系化合物等が挙げられる。
【００１２】
本発明で用いるＦｅ粉末としては純鉄の他に、鋼（例えば還元鉄粉）、鋳鉄、銑鉄等を用いることが出来る。粉末の形状は特に限定するものではなく、球形状、樹枝状、片状、針状、角状、積層状、ロッド状、板状，海綿状等が使用できる。Ｆｅ粉末の粒径は、特に限定されないが、５０〜５００μｍ程度の粒径を有しているものが、好適に使用できる。
【００１３】
本発明で用いるＮｉ粉末は純Ｎｉ粉末、工業用Ｎｉ粉末の他にフェロニッケル粉末等が含まれる。一般的に入手可能な工業用Ｎｉ紛末は１０〜１００μｍの粒径を有しており、更には、１〜１０μｍ程度の微粒Ｎｉ紛末も好適に使用可能である。
【００１４】
本発明においては、前記のＦｅ粉末とＮｉ粉末の混合物を、機械的合金化法とも呼ばれているＭＡ法により合金化（部分合金化を含む）して調製する。ＭＡ法による合金化及び部分合金化処理剤は有機ハロゲン化合物の分解能に極めて優れ、分解反応時のＮｉの溶出も大幅に抑制される。特にＦｅ成分に対するＮｉ成分の混合量及び混合状態、すなわち最適な合金化、部分合金化状態とすることが必要である。Ｆｅ粉末１００重量部に対しＮｉ粉末を０．０１〜２重量部、好ましくは０．１〜０．５重量部、更に好ましくは０．１〜０．３重量部混合させる。この範囲において驚くべきことに被処理物の還元分解能は著しく向上する。Ｎｉ粉末が０．０１重量部未満では有機ハロゲン化合物の分解能は低下し、Ｎｉ粉末無添加であるＦｅ粉末のみの分解能と同程度となり、分解能が不十分である。Ｎｉ粉末２重量部を超えても分解能はこれ以上高くはならず、コストの面で相当不利となる。
【００１５】
以下に、本発明のＭＡ法による金属系処理剤の製造方法について説明する。
【００１６】
前記のＦｅ粉末およびＮｉ粉末を所定の組成に調整し、一般的なボ−ルミル，Ｖミキサ−等により混合し均質化する。また、場合によっては、ＭＡ法装置に定量供給機等を採用して、混合工程を省くことも可能である。ＭＡ法に使用する装置としては、一例としてアトライタ−ミル（攪拌ボ−ルミル、アトリッションミルとも呼ばれる）、振動ミル、回転ミル（メカノフユ−ジョン含む）のバッチ式または連続式粉砕機を使用する。加工条件は、使用する装置により異なり一義的に定められないが、通常各装置の仕様条件の範囲内で採用できる。これらの装置の中で加工時間を最小とすることができるアトライターミルが特に好ましく、その加工条件としては、Ｆｅ粉末とＮｉ粉末の混合物１重量部に対して、鋼球等の粉砕メディアを７〜１５倍仕込む。原料が加工中に空気酸化する恐れがある場合は窒素ガス等の不活性ガスを流すことができる。ミル回転数は２００〜８００ｒｐｍが好適である。加工時間は、特に制限されないが、０．５〜５０時間が高い分解活性を発現できるため好ましい。加工時間を０．５〜６時間とした場合には、Ｆｅ粉末内および表面にＮｉ成分が偏析した部分合金となり、高い活性を得ることができ特に好ましい。
【００１７】
以上の製法で得られた処理剤の粉末形状は特に限定するものではなく、球形状、樹枝状、片状、針状、角状、積層状、ロッド状、板状、海綿状等が含まれる。また処理剤の比表面積は０．０５ｍ^２／ｇ以上、好ましくは０．２〜１０ｍ^２／ｇ、また２００μｍのふるいを通過する粒径、望ましくは３０〜１００μｍを用いることにより、分解反応速度や接触確率を向上させることができる。特に比表面積が０．２ｍ^２／ｇ以上、粒径７５μｍ以下の処理剤を使用すれば難分解性と言われているＣｉｓ−ＤＣＥ、ＭＣ、ＰＣＥをも、より短時間に分解することができるのでより好ましい。これ以下の細かい粒径を用いると地下水汚染下で使用する場合、処理剤充填部分で目つまりを起こし地下水の流れを止めてしまう可能性があり、土壌中に分散する際も飛散等が起こりハンドリングに問題がある。一方、粒径が大きすぎると汚染地下水，土壌に使用する際、被処理物との接触確率が悪くなり分解能が著しく低下する。
【００１８】
次に、本発明で使用する酸化剤としてはオゾン、次亜塩素酸ナトリウム、さらし粉、酸化亜鉛、酸化チタン、過酸化水素、過硫酸塩、過マンガン酸塩、ヒドロキシルラジカル等が挙げられるが、その内、過酸化水素、過硫酸塩、過マンガン酸塩又はヒドロキシルラジカルより選ばれる少なくとも１種類であることが好ましい。また、酸化剤を溶媒中に含ませることにより取扱いが容易となり好ましい。殊に、過硫酸塩、過酸化水素は水溶液で容易に取り扱うことができる為、特に好ましい。
【００１９】
本発明の無害化処理方法としては、有機ハロゲン化合物で汚染された被処理物に前記金属系処理剤および前記酸化剤を同時添加、混合する処理法、または前記金属系処理剤を添加、混合後、更に前記酸化剤を添加、混合する処理法が例示される。酸化剤の添加時期は被処理物の汚染度合い、性質、金属系処理剤添加量等により異なるが、無害化処理された被処理物中のＶＯＣ濃度をモニタリングしながら添加、混合することが望ましい。また、前記金属系処理剤および前記酸化剤を添加、混合する装置に付いては制限は無く、均一且つ、短時間に添加、混合することが望ましい。例えば、１）掘削した土壌をパイル状に積み上げ本発明の無害化処理剤を添加し、ドラム型スクラバ−、改質ミキサ−、ニ−ダ−等による連続均一混合処理する方法やバックホウ等による回分混合処理後埋め戻す方法、またはパイル状に積み上げ養生する方法、２）汚染土壌中に縦または横井戸を堀り、無害化処理剤を高圧空気または高圧水で注入する原位置処理法、３）無害化処理剤、分散剤、反応促進剤等をスラリ−状にして土壌に注入する方法、４）揚水した汚染地下水等に対しては無害化処理剤を充填した処理塔を通す連続処理法、５）汚染地下水の周辺を掘削する際に発生した砂利、石、岩等をジョ−クラッシャ−等で粉砕し、無害化処理剤と混合し、直接または地下水の流れる穴を空けた容器に仕込み、井戸に埋め戻す方法、６）汚染地下水位置より低い部分に無害化処理剤層を設けた浄化ピット法等ができる。
【００２０】
前記金属系処理剤および前記酸化剤の添加量は、浄化対象である被処理物の汚染濃度等により変動するが、本発明の金属系処理剤および酸化剤の組み合わせが非常に高活性であることから、従来剤に比較し、少ない添加量で環境基準値以下への浄化が達成できる。本発明の金属系処理剤の添加量は、その分解活性及び経済性を考慮すると、湿体土壌や地下水等の被処理物に対して０．１〜１０重量％、特に１〜５重量％であることが好ましい。また、酸化剤の添加量は、前記金属系処理剤の添加量、土壌水分、混合方法等により異なるが、被処理物に対して０．１〜２０重量％、特に０．５〜１０重量％であることが好ましい。
【００２１】
【実施例】
次に、本発明を実施例によりさらに具体的に説明するが、本発明はこれらの実施例によって何等限定されるものではない。
【００２２】
実施例では、ＭＡ法に用いる原料鉄粉として、還元鉄粉（川崎製鉄（株）製、商品名ＫＩＰ１００ＴまたはＫＩＰ−Ｅ２５Ｒ）、また原料Ｎｉ粉としては添川理化学社製Ｎｉ粉（純度９９％、粒径２〜３μｍグレ−ド品）を用いた。
【００２３】
実施例１〜５および比較例１〜３
ＰＣＥ含有汚染水溶液に対する本発明の無害化処理方法を検討した。１２５ｍｌバイアル瓶に１０ｐｐｍのＰＣＥ水溶液を１００ｍｌ、そして金属系処理剤１ｇ（対水溶液１重量％）を添加後、密封した。さらに５日後、酸化剤として３５％過酸化水素水溶液を１ｇ（対水溶液１重量％）、または１０％過硫酸ナトリウム水溶液を０．５ｇ（対水溶液０．５重量％）添加した。反応条件として３０℃、２００ｒｐｍ振とうを維持した。尚、この水溶液は脱溶存酸素処理、ｐＨ調整は行っていない。
【００２４】
次に、金属系処理剤のＭＡ法による加工条件を以下に示す。
【００２５】
実施例１〜５および比較例１では、還元鉄粉（川崎製鉄製ＫＩＰ１００Ｔ）および所定量のＮｉ粉（添川理化学社製）からなる原料１ｋｇをボ−ルミルで１０分間混合後，５Ｌポットを有するアトライターミル（三井鉱山（株）製、商品名ＤＹＮＡＭＩＣＭＩＬＬ、ＭＡ１Ｄ型）内に鋼球（ＳＵＪ２）７．５ｋｇと一緒に仕込み、ＭＡ加工した。この際の窒素ガス流量は４０ｍｌ／分とした。実施例１、３〜５は部分合金粉末を得るため、ＭＡ加工１時間、回転数４００ｒｐｍとした。また、実施例２および比較例１は合金粉末を得るため、ＭＡ加工２２時間、回転数６００ｒｐｍとした。
【００２６】
金属系処理剤の組成は表１に示すように実施例１〜３、５および比較例１は、Ｆｅ粉末１００重量部に対しＮｉ粉末量は０．３重量部に調整した剤、実施例４はＦｅ粉末１００重量部に対しＮｉ粉末量は０．９９重量部に調整した剤である。
【００２７】
尚、今回用いた金属系処理剤（ＭＡ剤）の比表面積は０．２ｍ^２／ｇ、７５μｍのふるいを通過した粉末を用いた。
【００２８】
比較例１では酸化剤を添加せず、金属系処理剤（ＭＡ剤）のみを１重量％添加した。
【００２９】
比較例２では金属系処理剤を使用せず、酸化剤として３５％過酸化水素を１重量％添加した。
【００３０】
比較例３では金属系処理剤として還元鉄粉（川崎製鉄（株）製、商品名ＫＩＰ−１００Ｔ）を１重量％添加、混合した後、５日後に３５％過酸化水素水を１重量％添加、混合した。
【００３１】
ＰＣＥ濃度の分析方法としては、環境省告示第１８号記載のＪＩＳＫ０１２５（用水、排水中の揮発性有機化合物試験方法）に基づいたヘッドスペース法を用い、ＰＣＥ濃度を経時的に定量分析し、金属系処理剤又は過酸化水素を添加後、１日、５日および１０日目のＰＣＥ濃度を測定した。また、ＰＣＥ濃度が環境基準値未満になった分解日数を求め、これらの結果を表１に示し、ＰＣＥ濃度の経時変化を図１に示した。
【００３２】
【表１】

実施例１〜４は前記金属系処理剤を１重量％添加、混合し、５日後に酸化剤として過酸化水素水または過硫酸ナトリウム（ペルオキソニ硫酸ナトリウム）水溶液を添加、混合した系である。実施例５は前記金属系処理剤を１重量％と酸化剤として３５％過酸化水素水を１重量％同時に添加、混合した系である。図１から分かるように、金属系処理剤（ＭＡ剤）を添加、混合すると１日後からＰＣＥ濃度が低下傾向を示す。表１には示していないが，同時に分解生成物としてエチレンが認められ、環境基準項目の有機塩素系化合物は生成していないことを確認した。さらに５日後、３５％過酸化水素水溶液を１重量％、または１０％過硫酸ナトリウムを０．５重量％添加、混合すると５日後、つまり、無害化処理をはじめて１０日以内には環境基準値（＝０．０１ｐｐｍ）未満となった。
【００３３】
これに対し、金属系処理剤（ＭＡ剤）のみを１重量％添加した系の比較例１では１０日後において分解生成物としてエチレンのみが認められ、ＴＣＥ，塩化ビニル等は認められなかったが、ＰＣＥ濃度は環境基準値（＝０．０１ｐｐｍ）未満とはならなかった。
【００３４】
酸化剤として３５％過酸化水素水のみを１重量％添加した系の比較例２では初期にはＰＣＥ濃度が一時的に低下するが、その後ほとんど分解が進まなかった。
【００３５】
金属系処理剤として鉄粉（ＫＩＰ−１００Ｔ）を１重量％添加した後、酸化剤として３５％過酸化水素水のみを１重量％添加、混合した系の比較例３は、金属系処理剤（ＫＩＰ−１００Ｔ）を添加した初期にはＰＣＥ濃度がほとんど分解せず、分解副生物としてＴＣＥ、塩化ビニルが認められた。さらに、酸化剤として３５％過酸化水素水を添加後も顕著に分解は進まなかった。
【００３６】
従って、実施例１〜５で用いた金属系処理剤（ＭＡ剤）及び酸化剤を用いた処理方法により汚染地下水で多くの事例のある難分解性といわれるＰＣＥを含む水溶液を分解する能力は顕著であり、短期間に環境基準値をクリアできることが分った。また、ＰＣＥにより汚染された土壌においても本発明剤および処理方法を使用することにより無害化できることは言うまでもない。
【００３７】
実施例６〜１０および比較例４〜６
ＶＯＣとして１，１−ＤＣＥ、ＴＣＥ及びＣｉｓ−ＤＣＥを取り上げ、これらのＶＯＣを含有する砂質汚染土壌の無害化処理を行なった。処理方法としては１，１−ＤＣＥ，ＴＣＥおよびＣｉｓ−ＤＣＥを含有する汚染土壌２７ｇ（含水率３３重量％）、そして金属系処理剤０．２７ｇ（対土壌１重量％）を１２５ｍｌバイアル瓶に入れてスパチュラにより３分間混合後、密封した。さらに１４日後、酸化剤として３５％過酸化水素水溶液を０．８１ｇ（対土壌３重量％）、または１０％過硫酸ナトリウム水溶液を０．４１ｇ（対土壌１．５重量％）添加後、スパチュラにより３分間混合した。反応条件として３０℃、静置状態とした。なお、土壌中の含水調整に用いた水は脱溶存酸素処理、ｐＨ調整は行っていない。
【００３８】
次に、今回用いた金属系処理剤（ＭＡ剤）の製造条件を以下に示す。
【００３９】
実施例６〜１０および比較例４は、還元鉄粉（川崎製鉄製ＫＩＰ−Ｅ２５Ｒ）および所定量のＮｉ粉（添川理化学社製）からなる原料１ｋｇをボ−ルミルで１０分間混合後，５Ｌポットを有するアトライターミル（三井鉱山（株）製、商品名ＤＹＮＡＭＩＣＭＩＬＬ、ＭＡ１Ｄ型）内に鋼球（ＳＵＪ２）７．５ｋｇと一緒に仕込み、ＭＡ加工した。この際の窒素ガス流量は４０ｍｌ／分とした。実施例６、８〜１０および比較例４は部分合金粉末を得るため、ＭＡ加工１時間、回転数４００ｒｐｍとした。また、実施例７は合金粉末を得るため、ＭＡ加工２２時間、回転数６００ｒｐｍとした。金属系処理剤の組成は表２に示すように実施例６〜８、１０および比較例４はＦｅ粉末１００重量部に対しＮｉ粉末量は０．３重量部に調整した剤、実施例９はＦｅ粉末１００重量部に対しＮｉ粉末量は０．９９重量部に調整した剤である。比較例６はＮｉを含まない還元鉄粉（川崎製鉄（株）製、商品名ＫＩＰ−Ｅ２５Ｒ）である。
【００４０】
尚、今回用いた金属系処理剤の比表面積は０．２５ｍ^２／ｇ、７５μｍのふるいを通過した粉末を用いた。
【００４１】
実施例６〜９では前記金属系処理剤（ＭＡ剤）を１重量％添加、混合後、１４日後に酸化剤として３５％過酸化水素水を３重量％または１０％過硫酸ナトリウム水溶液１．５重量％を添加、混合した。実施例１０は前記金属系処理剤を１重量％と酸化剤として３５％過酸化水素水３重量％を同時に添加、混合した系である。
【００４２】
比較例４では酸化剤を添加せず、金属系処理剤（ＭＡ剤）のみを１重量％添加した。
【００４３】
比較例５では金属系処理剤を添加せず、酸化剤として３５％過酸化水素水３重量％のみを添加した。
【００４４】
比較例６では金属系処理剤として還元鉄粉（ＫＩＰ−Ｅ２５Ｒ）を１重量％添過後、１４日後に３５％過酸化水素水溶液を３重量％添加、混合した。
【００４５】
各ＶＯＣ濃度の分析方法としては、環境省告示第１８号記載ＪＩＳＫ０１２５（用水、排水中の揮発性有機化合物試験方法）に基づいたヘッドスペース法を用い、ＶＯＣ濃度を経時的に定量分析し、金属系処理剤（ＭＡ剤）添加後、１日、７日、１４日および２１日目のＶＯＣ濃度を測定した。また、ＶＯＣ濃度が環境基準値未満になった分解日数を求め、これらの結果を表２に示し、汚染土壌中の各ＶＯＣ濃度の経時変化を図２〜４に示した。
【００４６】
【表２】

実施例６〜９は前記金属系処理剤（ＭＡ剤）を添加、混合、１４日後に酸化剤として３５％過酸化水素水または１０％過硫酸ナトリウム水溶液を添加、混合した系である。実施例１０は前記金属系処理剤を１重量％と酸化剤として３５％過酸化水素水を３重量％同時に添加、混合した系である。図２からも分かるように、金属系処理剤（ＭＡ剤）を添加、混合すると７日後には１，１−ＤＣＥ，ＴＣＥ，Ｃｉｓ−ＤＣＥ共、濃度が低下傾向を示すが、環境基準値をクリアできなかった。なお、この時点で表２には示していないが，分解生成物としてエチレンおよびエタンが認められたが、環境基準項目の有機塩素系化合物は副生していないことを確認した。さらに１４日後、３０％過酸化水素水溶液を３重量％、または１０％過硫酸ナトリウムを１．５重量％添加、混合すると７日後、つまり、無害化処理をはじめて２１日後までには１，１−ＤＣＥ，ＴＣＥ，Ｃｉｓ−ＤＣＥ濃度は各環境基準値（０．０２ｐｐｍ、０．０３ｐｐｍ及び０．０４ｐｐｍ）未満となった。
【００４７】
これに対し、金属系処理剤（ＭＡ剤）のみを１重量％添加した系の比較例４では、２１日後において分解生成物としてはエチレンおよびエタンが認められたが、各ＶＯＣの環境基準をクリアすることはできなかった。
【００４８】
酸化剤として３５％過酸化水素水のみを添加した系の比較例５では、初期には各ＶＯＣ共、低下する傾向に有るが、その後ほとんど分解が進まなかった。
【００４９】
還元鉄粉（ＫＩＰ−Ｅ２５Ｒ）を１重量％添加、混合、１４日後に３５％過酸化水素水を添加、混合した系の比較例６は還元鉄粉を添加、混合した直後ではほとんど分解せず、分解副生物として塩化ビニルが認められた。１４日後に過酸化水素水を添加した直後に各ＶＯＣが低下するが、環境基準値はクリアできなかった。
【００５０】
従って、実施例６〜１０で用いた金属系処理剤（ＭＡ剤）及び酸化剤を用いた無害化処理方法により、汚染土壌においても難分解性といわれているＣｉｓ−ＤＣＥ等を分解する能力は顕著であり、短期間に、かつ分解副生物として環境基準対象物を生成せずに法的規制値をクリアできることが分った。
【００５１】
【発明の効果】
以上の説明から明らかなように、本発明の金属系処理剤すなわちメカニカルアロイング法（ＭＡ法）により得たＦｅ−Ｎｉ合金粉末および酸化剤の組み合わせによる処理方法によれば、土壌、産業廃棄物、汚泥、スラッジ、排水、地下水中の有機ハロゲン化合物を短時間に、環境基準値以下まで分解し、有害な副生物を生成せずに無害化処理できる効果を有するものである。
【図面の簡単な説明】
【図１】ＰＣＥ含有水溶液に対し、金属系処理剤および酸化剤の組み合わせによる処理方法毎のＰＣＥ濃度の経時変化を示した図。
【図２】ＶＯＣ汚染土壌に対し、金属系処理剤および酸化剤の組み合わせによる処理方法毎の１，１−ＤＣＥ濃度の経時変化を示した図。
【図３】ＶＯＣ汚染土壌に対し、金属系処理剤および酸化剤の組み合わせによる処理方法毎のＴＣＥ濃度の経時変化を示した図。
【図４】ＶＯＣ汚染土壌に対し、金属系処理剤および酸化剤の組み合わせによる処理方法毎のＣｉｓ−ＤＣＥ濃度の経時変化を示した図。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for detoxifying an object to be treated such as soil, industrial waste, sludge, sludge, wastewater, and groundwater contaminated with an organic halogen compound.
[0002]
[Prior art]
Environmental pollution problems caused by organic halogen compounds such as TCE (trichloroethylene), PCE (tetrachloroethylene), dichloromethane, PCB (polychlorinated biphenyl), and dioxins have become remarkable in various parts of the world and have become a serious problem.
[0003]
In order to solve these problems, in particular, a treatment agent for detoxifying soil, wastewater, groundwater, and the like contaminated with a volatile organic halogen compound (hereinafter abbreviated as VOC) and a treatment method thereof have been studied. An application has been filed.
[0004]
1) In the case of polluted drainage water, groundwater, etc., a vacuum extraction method, a pumping aeration method, etc. are known, but a lifting device to the ground, an adsorption facility for the contaminated material pulled up, a regeneration treatment of an activated carbon adsorbent, and a generated waste. Processing of the object is required, and the entire construction is a high-cost processing method. In addition, detoxification requires several years, and complete removal is a difficult technology. In recent years, a detoxification treatment method for reducing and dehalogenating contaminants with a metal-based treatment agent has been reported, and it is stated that the cost can be reduced as compared with the conventional method. A method of detoxification with an iron-based treating agent has been proposed (for example, see Patent Document 1). However, it is necessary to remove dissolved oxygen by supplying hydrogen and the like to polluted wastewater and groundwater, and it is necessary to remove contaminated groundwater. Adaptation seems difficult. As another method, a permeable wall construction method in which an iron-based treatment agent is mixed into a groundwater area has been proposed (for example, see Patent Documents 2 and 3). However, this method also requires a long treatment time and cannot be completely purified. On the other hand, a detoxification treatment method by oxidation has been proposed (for example, see Patent Documents 4 to 6), but secondary contamination is feared due to the addition of a high concentration of permanganate, and an appropriate oxidizing agent is used. It is considered that it is difficult to control the addition amount of Pb in terms of operation and detoxification processing is difficult.
2) As a method for treating contaminated soil, sludge, sludge, and the like, a containment process is mainly used, but a thermal desorption method and a thermal decomposition method in which a heating electrode is inserted into excavated soil or directly into soil to perform a heat treatment are also known. . This method requires a large heating device. In addition, the vicinity of the electrode is thermally decomposed, but the others are volatilized on the ground mainly in VOCs and are not a fundamental treatment method. The soil after treatment is solidified by heat, and microorganisms almost die, which is a point of reuse. But hiring is difficult. Although there is a bioremediation method in which detoxification is performed by using a reducing substance via microorganisms, detoxification requires a long time, and cannot be applied to all kinds of soils, and complete detoxification is impossible. As an example in which an iron-based treating agent is added to contaminated soil as a chemical treatment, a method of forming a continuous purification wall in which iron powder is mixed (for example, see Patent Document 7) is to mix excavated soil with an iron-based treating agent. A method has been proposed in which a pile (mountain) is piled up on the ground and then left standing (for example, see Patent Document 8), but a long time is required for purification. On the other hand, a method of adding hydrogen peroxide or persulfate to iron powder has been proposed as an oxidation treatment method (see, for example, Patent Documents 9 to 10), but purification requires a long time. As another method, a treatment method in which one of metal iron, iron sulfate, and iron chloride and an oxidizing agent are added has been proposed (for example, Patent Document 11), but since a decomposition reaction proceeds only by a special mixing method, It is desired to improve iron-based treating agents.
[0005]
[Patent Document 1]
Japanese Patent Publication No. 49798/1995 (Claims)
[Patent Document 2]
Japanese Patent No. 3216014 (Claims)
[Patent Document 3]
JP-A-2002-79206 (Claims)
[Patent Document 4]
JP-A-2000-210683 (Claims)
[Patent Document 5]
JP-A-2002-301486 (Claims)
[Patent Document 6]
JP-A-2002-33280 (Claims)
[Patent Document 7]
JP 2001-321762 A (Claims)
[Patent Document 8]
JP-A-2001-00577 (Claims)
[Patent Document 9]
JP-A-2002-119977 (Claims)
[Patent Document 10]
JP-A-2002-307049 (Claims)
[Patent Document 11]
JP-A-2002-326080 (Claims)
[0006]
[Problems to be solved by the invention]
As mentioned above, conventional treatment methods for soil, industrial waste, sludge, sludge, wastewater, groundwater, etc. contaminated with organic halogen compounds are not technologies to actively decompose and detoxify pollutants, There are problems such as a long processing period of 10 to 20 years, high cost, a complicated processing method, and a large environmental load.
[0007]
An object of the present invention is to be able to meet the environmental standards applied to the organic halogen compound in the object to be treated in a short period of time, to use a simple and low-cost treatment method, and to contaminate the soil contaminated with the organic halogen compound having a small environmental load. An object of the present invention is to provide a method for detoxifying an object to be treated such as industrial waste, sludge, sludge, wastewater, and groundwater.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present inventor has proposed a metal-based treating agent having high decomposability, that is, a treating method using a combination of an Fe—Ni alloy obtained by a mechanical alloying (hereinafter abbreviated as MA) method and an oxidizing agent. investigated.
[0009]
That is, a metal-based treating agent and an oxidizing agent composed of an alloy powder obtained by the MA method are mixed with a mixture of 0.01 to 2 parts by weight of Ni powder with respect to 100 parts by weight of Fe powder, and mixed with the object. According to the treatment agent and the treatment method of the present invention, the concentration of the contaminated organic halogen compound can be reduced to an environmental standard value or less in a short period of time. Furthermore, it can also decompose Cis-DCE (cis-1,2-dichloroethylene), MC (methyl chloroform, or 1,1,1-trichloroethane), and PCE, which are said to be hardly decomposable.
[0010]
Hereinafter, the present invention will be described in detail.
[0011]
In the detoxification treatment method of the present invention, an object to be detoxified is one that is contaminated with an organic halogen compound. Examples of the organic halogen compound include dichloromethane, carbon tetrachloride, chloroform, 1,2-dichloroethane, 1,1-DCE (1,1-dichloroethylene), Cis-DCE, and Trans-DCE (trans-1,2-dichloroethylene). ), MC, 1,1,2-trichloroethane, TCE, PCE, 1,3-dichloropropene, and the like, or organic bromine-based compounds thereof.
[0012]
As the Fe powder used in the present invention, besides pure iron, steel (for example, reduced iron powder), cast iron, pig iron and the like can be used. The shape of the powder is not particularly limited, and spheres, dendrites, flakes, needles, squares, laminates, rods, plates, sponges, and the like can be used. The particle size of the Fe powder is not particularly limited, but those having a particle size of about 50 to 500 μm can be suitably used.
[0013]
The Ni powder used in the present invention includes pure Ni powder, industrial Ni powder, and ferronickel powder. Generally available industrial Ni powder has a particle size of 10 to 100 μm, and fine Ni powder of about 1 to 10 μm can also be suitably used.
[0014]
In the present invention, the mixture of the above-described Fe powder and Ni powder is prepared by alloying (including partial alloying) by an MA method also called a mechanical alloying method. The alloying and partial alloying treatment agents by the MA method are extremely excellent in resolving power of the organic halogen compound, and significantly suppress the elution of Ni during the decomposition reaction. In particular, it is necessary to set the mixed amount and the mixed state of the Ni component to the Fe component, that is, the optimum alloying and partial alloying states. 0.01 to 2 parts by weight, preferably 0.1 to 0.5 parts by weight, more preferably 0.1 to 0.3 parts by weight of Ni powder is mixed with 100 parts by weight of Fe powder. Surprisingly, in this range, the reduction ability of the object to be treated is significantly improved. If the Ni powder content is less than 0.01 parts by weight, the resolution of the organic halogen compound is reduced, and it is almost the same as the resolution of the Fe powder alone without addition of the Ni powder, and the resolution is insufficient. Even if the Ni powder content exceeds 2 parts by weight, the resolution does not increase any more, which is a considerable disadvantage in cost.
[0015]
Hereinafter, a method for producing a metal-based treating agent by the MA method of the present invention will be described.
[0016]
The above-mentioned Fe powder and Ni powder are adjusted to a predetermined composition, mixed and homogenized by a general ball mill, V mixer and the like. In some cases, the mixing process can be omitted by adopting a quantitative feeder or the like in the MA method apparatus. As an apparatus used in the MA method, for example, a batch type or continuous type pulverizer such as an attritor mill (also referred to as a stirring ball mill or an attrition mill), a vibration mill, a rotary mill (including a mechanofusion) is used. . The processing conditions vary depending on the equipment used and cannot be unambiguously determined, but can usually be adopted within the range of the specification conditions of each equipment. Among these devices, an attritor mill which can minimize the processing time is particularly preferable. The processing conditions are as follows. One part by weight of a mixture of Fe powder and Ni powder is mixed with a pulverizing medium such as a steel ball. Prepare ~ 15 times. In the case where the raw material may be oxidized by air during processing, an inert gas such as nitrogen gas can be flowed. The mill rotation speed is preferably from 200 to 800 rpm. The processing time is not particularly limited, but is preferably 0.5 to 50 hours because high decomposition activity can be exhibited. When the processing time is 0.5 to 6 hours, a partial alloy in which the Ni component is segregated in and on the surface of the Fe powder is obtained, and high activity can be obtained, which is particularly preferable.
[0017]
The shape of the powder of the treating agent obtained by the above manufacturing method is not particularly limited, and includes a spherical shape, a dendritic shape, a flaky shape, a needle shape, a square shape, a laminated shape, a rod shape, a plate shape, a spongy shape and the like. . The specific surface area of the treating agent is 0.05 m ² / g or more, preferably 0.2 to 10 m ² / g, and the particle diameter passing through a 200 μm sieve, desirably 30 to 100 μm, allows the decomposition reaction rate and The contact probability can be improved. In particular, if a treating agent having a specific surface area of 0.2 m ² / g or more and a particle size of 75 μm or less is used, it is possible to decompose Cis-DCE, MC, and PCE, which are said to be hardly decomposable, in a shorter time. It is more preferable. When used under groundwater contamination, fine particles with a diameter smaller than this may cause clogging at the treatment agent filled part and stop the flow of groundwater, and when dispersed in soil, scattering may occur and handling may occur. There is a problem. On the other hand, if the particle size is too large, when used for contaminated groundwater or soil, the probability of contact with the object to be treated is reduced, and the resolution is significantly reduced.
[0018]
Next, as the oxidizing agent used in the present invention, ozone, sodium hypochlorite, bleaching powder, zinc oxide, titanium oxide, hydrogen peroxide, persulfate, permanganate, hydroxyl radical and the like. Of these, at least one selected from hydrogen peroxide, persulfate, permanganate and hydroxyl radical is preferable. In addition, it is preferable to include an oxidizing agent in the solvent because handling becomes easy. Particularly, persulfate and hydrogen peroxide are particularly preferable because they can be easily handled in an aqueous solution.
[0019]
As the detoxification treatment method of the present invention, a treatment method in which the metal-based treatment agent and the oxidizing agent are simultaneously added to and mixed with an object to be treated contaminated with an organic halogen compound, or after the metal-based treatment agent is added and mixed. And a treatment method of adding and mixing the oxidizing agent. The timing of adding the oxidizing agent varies depending on the degree of contamination and properties of the object to be treated, the amount of the metal-based treating agent added, and the like, but it is desirable to add and mix while monitoring the VOC concentration in the object that has been rendered harmless. The apparatus for adding and mixing the metal-based treating agent and the oxidizing agent is not limited, and it is desirable to add and mix uniformly and in a short time. For example, 1) excavated soil is piled up, a detoxifying agent of the present invention is added thereto, and a method of performing a continuous uniform mixing process using a drum type scrubber, a modified mixer, a kneader or the like, or a batching method using a backhoe or the like. 2) In-situ treatment method in which a vertical or horizontal well is dug in contaminated soil and a detoxifying agent is injected with high-pressure air or high-pressure water, 3) A method in which a detoxifying agent, a dispersing agent, a reaction accelerator, etc. are injected in the form of a slurry into soil; 4) a continuous treatment method in which contaminated groundwater pumped through a treatment tower filled with the detoxifying agent; 5) Gravel, stones, rocks, etc. generated when excavating around the contaminated groundwater are ground with a jo crusher or the like, mixed with a detoxifying agent, and charged directly or in a container provided with a hole through which groundwater flows. How to backfill wells, 6 Detoxification agent layer purification can pit method is provided in the lower groundwater contaminated located portion.
[0020]
The amount of addition of the metal-based treatment agent and the oxidizing agent varies depending on the contamination concentration of the object to be purified and the like, but the combination of the metal-based treatment agent and the oxidizing agent of the present invention has a very high activity. Therefore, purification to an environmental standard value or less can be achieved with a small amount of addition as compared with the conventional agent. The amount of the metal-based treating agent of the present invention is 0.1 to 10% by weight, particularly 1 to 5% by weight, based on the treatment target such as wet soil and groundwater, in consideration of its decomposition activity and economy. Preferably, there is. The amount of the oxidizing agent varies depending on the amount of the metal-based treating agent, soil moisture, mixing method, etc., but is 0.1 to 20% by weight, particularly 0.5 to 10% by weight based on the material to be treated. It is preferable that
[0021]
【Example】
Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
[0022]
In Examples, reduced iron powder (KIP100T or KIP-E25R, trade name, manufactured by Kawasaki Steel Co., Ltd.) was used as the raw material iron powder used in the MA method, and Ni powder (purity: 99%, manufactured by Soegawa Chemical Co., Ltd.) was used as the raw material Ni powder. Grade having a particle size of 2 to 3 μm) was used.
[0023]
Examples 1 to 5 and Comparative Examples 1 to 3
The detoxification method of the present invention for a PCE-containing contaminated aqueous solution was studied. 100 ml of a 10 ppm aqueous solution of PCE and 1 g of a metal-based treating agent (1% by weight with respect to the aqueous solution) were added to a 125 ml vial and sealed. After 5 days, 1 g of a 35% aqueous hydrogen peroxide solution (1% by weight of the aqueous solution) or 0.5 g of a 10% aqueous solution of sodium persulfate (0.5% by weight of the aqueous solution) was added as an oxidizing agent. The reaction conditions were 30 ° C. and 200 rpm shaking. This aqueous solution was not subjected to a dissolved oxygen treatment or a pH adjustment.
[0024]
Next, the processing conditions of the metal-based treating agent by the MA method are shown below.
[0025]
In Examples 1 to 5 and Comparative Example 1, 1 kg of a raw material composed of reduced iron powder (KIP100T manufactured by Kawasaki Steel) and a predetermined amount of Ni powder (manufactured by Soegawa Rikagaku Co., Ltd.) was mixed in a ball mill for 10 minutes, and then had a 5 L pot. The steel ball (SUJ2) was charged together with 7.5 kg into an attritor mill (trade name: DYNAMICCMILL, MA1D type, manufactured by Mitsui Mining Co., Ltd.) and subjected to MA processing. At this time, the nitrogen gas flow rate was 40 ml / min. In Examples 1, 3 to 5, in order to obtain a partial alloy powder, MA processing was performed for 1 hour and the number of revolutions was set to 400 rpm. Further, in Example 2 and Comparative Example 1, in order to obtain an alloy powder, the MA processing was performed for 22 hours and the number of revolutions was set to 600 rpm.
[0026]
As shown in Table 1, the compositions of the metal-based treating agents in Examples 1 to 3 and Comparative Example 1 were such that the amount of Ni powder was adjusted to 0.3 part by weight with respect to 100 parts by weight of Fe powder. Is an agent in which the amount of Ni powder is adjusted to 0.99 parts by weight with respect to 100 parts by weight of Fe powder.
[0027]
The metal-based treating agent (MA agent) used this time had a specific surface area of 0.2 m ² / g, and a powder passed through a 75 μm sieve was used.
[0028]
In Comparative Example 1, an oxidizing agent was not added, and only a metal-based treating agent (MA agent) was added at 1% by weight.
[0029]
In Comparative Example 2, 1% by weight of 35% hydrogen peroxide was added as an oxidizing agent without using a metal-based treating agent.
[0030]
In Comparative Example 3, 1% by weight of reduced iron powder (KIP-100T, manufactured by Kawasaki Steel Co., Ltd.) was added and mixed as a metal-based treating agent. After 5 days, 1% by weight of 35% hydrogen peroxide was added after 5 days. , Mixed.
[0031]
As a method for analyzing the PCE concentration, a headspace method based on JIS K0125 (Testing method for volatile organic compounds in water and wastewater) described in Notification No. 18 of the Ministry of the Environment was used. After the addition of the metal-based treating agent or hydrogen peroxide, the PCE concentration was measured on the 1st, 5th and 10th days. In addition, the number of decomposition days at which the PCE concentration became less than the environmental standard value was determined. The results are shown in Table 1, and the change over time of the PCE concentration is shown in FIG.
[0032]
[Table 1]

Examples 1 to 4 are systems in which 1% by weight of the metal-based treating agent was added and mixed, and after 5 days, an aqueous solution of hydrogen peroxide or an aqueous solution of sodium persulfate (sodium peroxodisulfate) was added and mixed. Example 5 is a system in which 1% by weight of the metal-based treating agent and 1% by weight of 35% aqueous hydrogen peroxide as an oxidizing agent were simultaneously added and mixed. As can be seen from FIG. 1, when the metal-based treating agent (MA agent) is added and mixed, the PCE concentration tends to decrease from one day later. Although not shown in Table 1, at the same time, ethylene was recognized as a decomposition product, and it was confirmed that no organic chlorine-based compound as an environmental standard item was produced. Five days later, 1% by weight of a 35% aqueous hydrogen peroxide solution or 0.5% by weight of 10% sodium persulfate was added and mixed, and after 5 days, that is, within 10 days after the detoxification treatment was started, the environmental standard value ( = 0.01 ppm).
[0033]
On the other hand, in Comparative Example 1 in which only 1% by weight of the metal-based treating agent (MA agent) was added, only ethylene was recognized as a decomposition product after 10 days, and TCE, vinyl chloride, etc. were not recognized. The PCE concentration did not fall below the environmental standard value (= 0.01 ppm).
[0034]
In Comparative Example 2 in which only 1% by weight of 35% aqueous hydrogen peroxide was added as an oxidizing agent, the PCE concentration temporarily decreased at the initial stage, but the decomposition hardly proceeded thereafter.
[0035]
After adding 1% by weight of iron powder (KIP-100T) as a metal-based treating agent, only 1% by weight of 35% hydrogen peroxide solution was added and mixed as an oxidizing agent. At the initial stage of the addition of KIP-100T), the PCE concentration hardly decomposed, and TCE and vinyl chloride were recognized as decomposition by-products. Further, the decomposition did not remarkably proceed even after adding 35% aqueous hydrogen peroxide as an oxidizing agent.
[0036]
Therefore, the ability to decompose an aqueous solution containing PCE, which is often referred to as hardly decomposable, in contaminated groundwater by the treatment method using the metal-based treating agent (MA agent) and the oxidizing agent used in Examples 1 to 5 is remarkable. It was found that environmental standards could be cleared in a short period of time. Needless to say, even soil contaminated by PCE can be rendered harmless by using the agent and the treatment method of the present invention.
[0037]
Examples 6 to 10 and Comparative Examples 4 to 6
1,1-DCE, TCE and Cis-DCE were taken as VOCs, and detoxification treatment of sandy contaminated soil containing these VOCs was performed. As the treatment method, 27 g of contaminated soil containing 1,1-DCE, TCE and Cis-DCE (water content 33% by weight), and 0.27 g of metal-based treatment agent (1% by weight with respect to soil) were put into a 125 ml vial. After mixing with a spatula for 3 minutes, the mixture was sealed. After 14 days, 0.81 g of a 35% hydrogen peroxide aqueous solution (3% by weight with respect to soil) or 0.41 g of a 10% aqueous solution of sodium persulfate (1.5% by weight with respect to soil) was added as an oxidizing agent. Mix for 3 minutes. The reaction conditions were 30 ° C. and a standing state. The water used for the adjustment of the water content in the soil was not subjected to the dissolved oxygen treatment and the pH adjustment.
[0038]
Next, the manufacturing conditions of the metal-based treating agent (MA agent) used this time are shown below.
[0039]
In Examples 6 to 10 and Comparative Example 4, 1 kg of a raw material composed of reduced iron powder (KIP-E25R manufactured by Kawasaki Steel) and a predetermined amount of Ni powder (manufactured by Soegawa Rikagaku Co., Ltd.) were mixed for 10 minutes by a ball mill, and then a 5 L pot was mixed. Was charged together with 7.5 kg of steel balls (SUJ2) in an attritor mill (trade name: DYNAMICCMILL, model MA1D, manufactured by Mitsui Mining Co., Ltd.), and subjected to MA processing. At this time, the nitrogen gas flow rate was 40 ml / min. In Examples 6, 8 to 10 and Comparative Example 4, in order to obtain a partial alloy powder, the MA processing was performed for 1 hour and the rotation speed was set to 400 rpm. In Example 7, in order to obtain an alloy powder, the MA processing was performed for 22 hours and the number of revolutions was set to 600 rpm. As shown in Table 2, the composition of the metal-based treating agent was as shown in Tables 6 to 8, 10 and Comparative Example 4 in which the amount of Ni powder was adjusted to 0.3 part by weight with respect to 100 parts by weight of Fe powder. The amount of the Ni powder was adjusted to 0.99 parts by weight with respect to 100 parts by weight of the Fe powder. Comparative Example 6 is a reduced iron powder containing no Ni (KIP-E25R, manufactured by Kawasaki Steel Corporation).
[0040]
The metal-based treating agent used this time had a specific surface area of 0.25 m ² / g, and a powder passed through a 75 μm sieve was used.
[0041]
In Examples 6 to 9, 1% by weight of the metal-based treating agent (MA agent) was added and mixed. After 14 days, 3% by weight of 35% aqueous hydrogen peroxide as an oxidizing agent or 1.5% aqueous solution of 10% sodium persulfate was added. % By weight was added and mixed. Example 10 is a system in which 1% by weight of the metal-based treating agent and 3% by weight of 35% aqueous hydrogen peroxide as an oxidizing agent were simultaneously added and mixed.
[0042]
In Comparative Example 4, the oxidizing agent was not added, and only the metal-based treating agent (MA agent) was added at 1% by weight.
[0043]
In Comparative Example 5, no metal-based treating agent was added, and only 3% by weight of 35% aqueous hydrogen peroxide was added as an oxidizing agent.
[0044]
In Comparative Example 6, 1% by weight of reduced iron powder (KIP-E25R) was added as a metal-based treating agent, and 14 days later, 3% by weight of a 35% aqueous hydrogen peroxide solution was added and mixed.
[0045]
As a method for analyzing each VOC concentration, a headspace method based on JIS K0125 (Testing method for volatile organic compounds in water and wastewater) described in Notification No. 18 of the Ministry of the Environment was used, and the VOC concentration was quantitatively analyzed with time. After the addition of the metal-based treatment agent (MA agent), the VOC concentrations were measured on the 1st, 7th, 14th and 21st days. In addition, the number of decomposition days when the VOC concentration became less than the environmental standard value was obtained, and the results are shown in Table 2. The time-dependent changes of the respective VOC concentrations in the contaminated soil are shown in FIGS.
[0046]
[Table 2]

Examples 6 to 9 are systems in which the metal-based treating agent (MA agent) was added and mixed, and after 14 days, 35% aqueous hydrogen peroxide or 10% aqueous sodium persulfate was added and mixed as an oxidizing agent. Example 10 is a system in which 1% by weight of the metal-based treating agent and 3% by weight of 35% aqueous hydrogen peroxide as an oxidizing agent were simultaneously added and mixed. As can be seen from FIG. 2, the concentration of 1,1-DCE, TCE, and Cis-DCE tends to decrease after 7 days when the metal-based treating agent (MA agent) is added and mixed. Could not clear. At this point, although not shown in Table 2, ethylene and ethane were recognized as decomposition products, but it was confirmed that no organic chlorine-based compound as an environmental standard item was produced as a by-product. After 14 days, 3% by weight of a 30% aqueous hydrogen peroxide solution or 1.5% by weight of 10% sodium persulfate was added and mixed, and after 7 days, that is, 1,1- The DCE, TCE, and Cis-DCE concentrations were below the respective environmental standard values (0.02 ppm, 0.03 ppm, and 0.04 ppm).
[0047]
On the other hand, in Comparative Example 4 in which only 1% by weight of the metal-based treating agent (MA agent) was added, ethylene and ethane were recognized as decomposition products after 21 days, but the environmental standards of each VOC were cleared. I couldn't.
[0048]
In Comparative Example 5 in which only 35% hydrogen peroxide solution was added as an oxidizing agent, each VOC tended to decrease at the initial stage, but hardly decomposed thereafter.
[0049]
Comparative Example 6 in which 1% by weight of reduced iron powder (KIP-E25R) was added and mixed, and 35% hydrogen peroxide was added and mixed 14 days later, almost no decomposition was observed immediately after adding and mixing reduced iron powder. In addition, vinyl chloride was recognized as a decomposition by-product. After 14 days, immediately after the addition of the aqueous hydrogen peroxide solution, each VOC decreased, but the environmental standard value could not be cleared.
[0050]
Therefore, the ability to degrade Cis-DCE and the like, which are said to be hardly decomposable even in contaminated soil, by the detoxification treatment method using the metal-based treating agent (MA agent) and the oxidizing agent used in Examples 6 to 10 is as follows. It was remarkable, and it was found that legally regulated values could be cleared in a short period of time and without generating environmental standards as decomposition by-products.
[0051]
【The invention's effect】
As is clear from the above description, according to the metal-based treating agent of the present invention, that is, the treating method using the combination of the Fe—Ni alloy powder obtained by the mechanical alloying method (MA method) and the oxidizing agent, soil and industrial waste It has the effect of decomposing organic halogen compounds in sludge, sludge, wastewater, and groundwater in a short time to below the environmental standard value, thereby enabling detoxification without generating harmful by-products.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram showing a change over time of a PCE concentration for each treatment method using a combination of a metal-based treatment agent and an oxidizing agent for a PCE-containing aqueous solution.
FIG. 2 is a diagram showing the change over time of the 1,1-DCE concentration for each treatment method of a VOC-contaminated soil with a combination of a metal-based treating agent and an oxidizing agent.
FIG. 3 is a diagram showing a change over time of the TCE concentration for each treatment method using a combination of a metal-based treatment agent and an oxidizing agent for VOC-contaminated soil.
FIG. 4 is a diagram showing a change over time in the concentration of Cis-DCE for each treatment method using a combination of a metal-based treating agent and an oxidizing agent for VOC-contaminated soil.

Claims

In a method of detoxifying an object to be treated contaminated with an organic halogen compound, an alloy obtained by mechanically alloying a mixture of 0.01 to 2 parts by weight of Ni powder with respect to 100 parts by weight of Fe powder on the object to be treated. A method for detoxifying an object to be treated contaminated with an organic halogen compound, comprising adding and mixing a metal-based treating agent and an oxidizing agent composed of powder.

2. The method for detoxifying an object to be treated contaminated with an organic halogen compound according to claim 1, wherein a metal-based treating agent is added and mixed, and then an oxidizing agent is added and mixed.

The method for detoxifying an object to be treated contaminated with an organic halogen compound according to claim 1, wherein the metal-based treating agent and the oxidizing agent are simultaneously added and mixed.

4. An object to be treated contaminated with an organic halogen compound according to claim 1, wherein the amount of the metal-based treating agent added is 0.1 to 10% by weight based on the object to be treated. Detoxification treatment method of goods.

The amount of the oxidizing agent added is from 0.1 to 20% by weight based on the amount of the object to be treated, and the amount of the object to be treated contaminated with the organic halogen compound according to any one of claims 1 to 4 is determined. Detoxification treatment method.

The harmless treatment of an object to be treated contaminated with an organic halogen compound according to any one of claims 1 to 5, wherein the alloy powder is a partial alloy powder in which a Ni component is segregated in and on the Fe powder. Treatment method.

The contamination with the organic halogen compound according to any one of claims 1 to 6, wherein the oxidizing agent is at least one selected from hydrogen peroxide, persulfate, permanganate, and hydroxyl radical. Harmless treatment method for the processed object.

The method for detoxifying an object to be treated contaminated with an organic halogen compound according to any one of claims 1 to 7, wherein an oxidizing agent is contained in the solvent.