JP3728510B2 - Soil pollution countermeasure method and soil pollution countermeasure system - Google Patents

Soil pollution countermeasure method and soil pollution countermeasure system Download PDF

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JP3728510B2
JP3728510B2 JP2003078139A JP2003078139A JP3728510B2 JP 3728510 B2 JP3728510 B2 JP 3728510B2 JP 2003078139 A JP2003078139 A JP 2003078139A JP 2003078139 A JP2003078139 A JP 2003078139A JP 3728510 B2 JP3728510 B2 JP 3728510B2
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武 長谷川
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Description

【０００１】
【発明の属する技術分野】
本発明は、広く土壌汚染対策の分野に属するものであり、特に土壌および地下水から汚染物質を除去して修復するための土壌汚染対策方法および土壌汚染対策システムに関する。
【０００２】
【従来の技術】
今日、トリクロロエチレン等に代表される環境負荷を与える有害物質による土壌汚染は、土壌汚染対策法の施行にも観られるように、重大な社会的問題として認識されつつある。かかる土壌汚染の対策に関する従来の技術として、例えば、地下の不飽和帯に存する汚染地層や汚染空気を対象とした真空吸引法、飽和帯に存する汚染地下水を対象とした揚水曝気法、スパージング法等が代表的な方策として知られている。これらの方策は、概して土壌に流体を注入し汚染を流体に移相させた後、その流体を回収して処理を行う技術であり、地質状況等に応じて使用する流体が異なる。
【０００３】
これら流体の注入および回収は、ストレーナ構造を有した井戸等により実施されるのが一般的であり、注入および回収点から同心円に近似される影響範囲内にて実施される。また、この影響範囲を広域に設置する必要のある場合は、例えば、特許文献１〜３に示されるように、一般には井戸を複数設置する方策が採られていた。また、特許文献４に示されるように、汚染地層毎に吸引井戸を設置し、汚染地層単位で汚染物質を吸引除去するという汚染回収方法も提案されている。
【０００４】
一方、前述した井戸を用いた流体の点的な注入および回収とは対照的に、所定の浸透施設により線的な領域にて流体を注入すると共に、汚染物質を含む流体を点的に回収する方策も、特許文献５に示されるように既に提案されている。更にまた、特許文献５に示された浸透施設と構造上で類似が見られるが、土壌中に蓋付の地中溝等の粒状体路を設けて、この粒状体路を介して周囲の汚染気体を主に回収する方策も、特許文献６に示されるように既に提案されている。
【０００５】
【特許文献１】
特開２００２−１１４５６号公報
【特許文献２】
特開２００２−３０１４６５号公報
【特許文献３】
特開平１１−１６９８３６号公報
【特許文献４】
特開平５−２３１０８６号公報
【特許文献５】
特開２００１−２２５０５４号公報
【特許文献６】
特開２００２−３４６５３９号公報
【０００６】
【発明が解決しようとする課題】
しかしながら、前述した特許文献１〜４に示された技術では、土壌汚染範囲の広がりに応じて、多数の井戸を垂直あるいは水平方向に設置することが前提となるため、おのずとその設置数、大きさ、対費用効果の面での限界もあり、現実の多くは必ずしも十分な本数の井戸を用いての理想的な土壌の修復を行うことのできる状況にはなかった。
【０００７】
また、特許文献５に示された技術では、土壌中に流体を注入するための線的なスクリーン構造部を地表面の広域に設置できるが、かかるスクリーン構造部は、液体を下方に流下させる機能のみに限定されていた。しかも、汚染物質が取り込まれた流体の回収は、前述した特許文献１〜４と同様に回収点付近の狭い範囲に限定されるため、広い範囲で回収するには、結局多数の井戸を設置する必要があった。
【０００８】
更にまた、特許文献６に示された技術では、溝状の粒状体路を土壌中に連続的に設けるとしても、結局は粒状体路に沿った限られた範囲内でしか、流体に含まれる汚染物質を回収することができないという問題があり、広い範囲で回収するには、土壌中に蜂の巣状ないし格子状に多数の粒状体路を設置する必要があった。
【０００９】
総じて、特許文献１〜６に示された技術では、流体の注入および回収が、井戸等を用いた地中部と、地中溝等を用いた地表部での実施に大別され、おのずとその対象流体、並びに汚染対策を施す範囲が限定されていた。また、地中深度が深くなるにつれて注入設備の設置の負担も大きくなり、影響範囲を広く設定することが、技術的にも対費用効果的にも難しくなる傾向にあった。
【００１０】
本発明は、以上のような従来技術が有する問題点に着目してなされたもので、土壌汚染修復で利用される各種流体の回収および注入に関していっそうの簡素化によるコスト低減を図ると共に、流体の注入および回収をより広域に展開して実施することが可能であり、極めて汎用性の高い土壌汚染対策方法および土壌汚染対策システムを提供することを目的としている。
【００１１】
【課題を解決するための手段】
発明者らは土壌汚染対策に関する鋭意検討により、土壌汚染の主たる拡散媒体である地下水の境界面に着目し、この境界付近に人工的な地層としての広域流体路層（１）を形成することにより、この広域流体路層（１）を通じて気体、液体を問わず回収並びに注入を容易かつ広範囲に実施可能なことを明らかにした。かかる結論に鑑みて、前述した目的を達成するための本発明の要旨とするところは、以下の各項に存する。
【００１２】
［１］土壌および地下水から汚染物質を除去して修復するための土壌汚染対策方法において、
地下の飽和帯（２）と不飽和帯（３）の境界部周辺に沿って、互いに連通する数多の間隙を含む広域流体路層（１）を設置し、
前記広域流体路層（１）を通じて、該広域流体路層（１）の周囲への流体の注入、および該広域流体路層（１）の周囲からの流体の回収のうち、少なくとも何れか一方による流体制御を行うことを特徴とする土壌汚染対策方法。
【００１３】
［２］前記広域流体路層（１）を通じて、前記流体である気体と液体の回収を並行して行うことを特徴とする［１］に記載の土壌汚染対策方法。
【００１４】
［３］地層構造を有しない汚染土壌を前記広域流体路層（１）上に積層させた後、前記広域流体路層（１）を通じての流体制御により、前記汚染土壌中の汚染物質を除去することを特徴とする［１］または［２］に記載の土壌汚染対策方法。
【００１５】
［４］汚染土壌を汚染濃度別に区域を指定して前記広域流体路層（１）上に積層させた後、前記区域毎に汚染濃度に応じた前記広域流体路層（１）を通じての流体制御により、前記汚染土壌中の汚染物質を除去することを特徴とする［１］または［２］に記載の土壌汚染対策方法。
【００１６】
［５］汚染土壌を混合し汚染物質濃度を平均化する操作、または客土を混入し更に汚染物質濃度を低くして平均化する操作を行った後、前記広域流体路層（１）を通じての流体制御により、前記汚染土壌中の汚染物質を除去することを特徴とする［１］または［２］に記載の土壌汚染対策方法。
【００１７】
［６］前記広域流体路層（１）の内部ないし周囲に難透過性壁（３１，３２）を設置し、該難透過性壁（３１，３２）により土壌間隙の連続性を一部遮断し流体流路を矯正することにより汚染除去を促すことを特徴とする［１］，［２］，［３］，［４］または［５］に記載の土壌汚染対策方法。
【００１８】
［７］前記広域流体路層（１）を通じての流体制御により、前記飽和帯（２）に地下水循環系を形成することを特徴とする［１］，［２］，［３］，［４］，［５］または［６］に記載の土壌汚染対策方法。
【００１９】
［８］地下水系を酸化雰囲気下に保つことを特徴とする［１］，［２］，［３］，［４］，［５］，［６］または［７］に記載の土壌汚染対策方法。
【００２０】
［９］地下水系にて好気性微生物の好気的代謝を利用した水処理を併せて行うことを特徴とする［１］，［２］，［３］，［４］，［５］，［６］，［７］または［８］に記載の土壌汚染対策方法。
【００２１】
［１０］地下水系を還元雰囲気下に保つことを特徴とする［１］，［２］，［３］，［４］，［５］，［６］または［７］に記載の土壌汚染対策方法。
【００２２】
［１１］地下水系にて嫌気性微生物の嫌気的代謝を利用した水処理を併せて行うことを特徴とする［１］，［２］，［３］，［４］，［５］，［６］，［７］，［８］または［１０］に記載の土壌汚染対策方法。
【００２３】
［１２］地下水の一部を、地上に設置した汚染処理装置（２３）を通じて浄化処理し、該汚染処理装置（２３）で処理した地下水を再び地下水系に戻すことにより、地下水を浄化することを特徴とする［１］，［２］，［３］，［４］，［５］，［６］，［７］，［８］，［９］，［１０］または［１１］に記載の土壌汚染対策方法。
【００２４】
［１３］地表部と前記飽和帯（２）下部より液体を注入し、該液体を前記広域流体路層（１）にて回収する流体流を形成することで、前記飽和帯（２）および前記不飽和帯（３）に存する汚染物質を除去することを特徴とする［１］，［２］，［３］，［４］，［５］，［６］，［７］，［８］，［９］，［１０］，［１１］または［１２］に記載の土壌汚染対策方法。
【００２５】
［１４］地下水面下より散気を行い、前記広域流体路層（１）を通じての吸気により、散気気体と共に汚染物質を回収することを特徴とする［１］，［２］，［３］，［４］，［５］，［６］，［７］，［８］，［９］，［１０］，［１１］，［１２］または［１３］に記載の土壌汚染対策方法。
【００２６】
［１５］土壌中の汚染物質の気化を促す操作と共に、前記広域流体路層（１）を通じての吸気により、気化した汚染物質を回収することを特徴とする［１］，［２］，［３］，［４］，［５］，［６］，［７］，［８］，［９］，［１０］，［１１］，［１２］，［１３］または［１４］に記載の土壌汚染対策方法。
【００２７】
［１６］前記汚染物質の気化を促す操作が、加熱した過酸化物溶液を土壌中に注入することであることを特徴とする［１５］に記載の土壌汚染対策方法。
【００２８】
［１７］前記広域流体路層（１）の上下面部の何れか少なくとも一方より略垂直方向に突出し、前記広域流体路層（１）と同様に互いに連通する数多の間隙を含み、該広域流体路層（１）に連通する凸様の補助構造物（５）を形成し、
前記広域流体路層（１）および前記補助構造物（５）を通じて、該広域流体路層（１）および該補助構造物（５）の周囲に対する流体の注入、および該広域流体路層（１）の周囲からの流体の回収のうち、少なくとも何れか一方による流体制御を実施することを特徴とする［１］，［２］，［３］，［４］，［５］，［６］，［７］，［８］，［９］，［１０］，［１１］，［１２］，［１３］，［１４］，［１５］または［１６］に記載の土壌汚染対策方法。
【００２９】
［１８］前記広域流体路層（１）の周囲を囲む遮水壁（３０）を地下に設置し、前記補助構造物（５）を、前記広域流体路層（１）の上面部周囲にて前記遮水壁（３０）の内側壁と一部または全面が接するように形成し、
前記遮水壁（３０）の外側周囲にて自然地下水位が最も高い地点にある遮水壁（３０）の一部を外側と連通可能に開放すること、または遮水壁（３０）内側に液体を注入することで、前記補助構造物（５）内における地下水位を、前記遮水壁（３０）の外側周囲における自然地下水位の最高位と略同位かそれ以上の高位に保つことを特徴とする［１７］に記載の土壌汚染対策方法。
【００３０】
［１９］前記広域流体路層（１）を難透水ないし遮水施工で仕切ることで、地下で互いに連通可能に区画された複数の反応部を形成し、これらの各反応部に一連の流体流を通過せしめることにより、前記各反応部が連結して成る汚染処理系を構築することを特徴とする［１］，［２］，［３］，［４］，［５］，［６］，［７］，［８］，［９］，［１０］，［１１］，［１２］，［１３］，［１４］，［１５］，［１６］，［１７］または［１８］に記載の土壌汚染対策方法。
【００３１】
［２０］土壌および地下水から汚染物質を除去して修復するための土壌汚染対策システムにおいて、
地下の飽和帯（２）と不飽和帯（３）の境界部周辺に沿って設置され、互いに連通する数多の間隙を含む広域流体路層（１）と、
地上より前記広域流体路層（１）に連通可能に設置した井戸様構造体（１０）とを有し、
前記井戸様構造体（１０）により前記広域流体路層（１）を通じて、該広域流体路層（１）の周囲に対する流体の注入、および該広域流体路層（１）の周囲からの流体の回収のうち、少なくとも何れか一方による流体制御を実施可能に構成したことを特徴とする土壌汚染対策システム。
【００３２】
［２１］前記広域流体路層（１）は、所定範囲で粒状物を密に集合させた状態に積層して成ることを特徴とする［２０］に記載の土壌汚染対策システム。
【００３３】
［２２］前記広域流体路層（１）の上下面部の何れか少なくとも一方より略垂直方向に突出し、前記広域流体路層（１）と同様に互いに連通する数多の間隙を含み、該広域流体路層（１）に連通する凸様の補助構造物（５）を形成したことを特徴とする［２０］または［２１］に記載の土壌汚染対策システム。
【００３４】
［２３］前記補助構造物（５）は、汚染物質の吸着または分解を促進する材質を含むことを特徴とする［２２］に記載の土壌汚染対策システム。
【００３５】
［２４］前記井戸様構造体（１０）は、地中に連通するストレーナ部（１１）を軸方向に複数設けて成り、各ストレーナ部（１１）の少なくとも１つを、前記広域流体路層（１）に連通する位置に配置させることを特徴とする［２０］，［２１］，［２２］または［２３］に記載の土壌汚染対策システム。
【００３６】
［２５］前記井戸様構造体（１０）の内部に、一の前記ストレーナ部（１１）から集水された地下水を他の前記ストレーナ部（１１）より土壌中に注入するためのポンプ（４０）を設け、
前記ポンプ（４０）の集水部を、該集水部より集水される地下水を濾過するストレーナ（４２）で覆い、
地上から通気可能な給気経路（１７）を前記井戸様構造体（１０）の内部に挿通し、該給気経路（１７）の下端出口を、前記集水部側より前記ストレーナ内側を臨む位置に配置させ、
地上まで連通する濾過物回収経路（４３）を前記井戸様構造体（１０）の内部に挿通し、該濾過物回収経路（４３）の下端に、前記ストレーナを囲む回収部（４４）を設け、
前記ポンプ（４０）の稼動に伴い前記ストレーナ表面に蓄積した濾過物を、前記給気経路（１７）からの通気により剥離した際に、該剥離した濾過物を前記濾過物回収経路（４３）により通気気体と共に地上に回収することを特徴とする［２４］に記載の土壌汚染対策システム。
【００３７】
本発明は次のように作用する。
本発明に係る前記［１］に記載の土壌汚染対策方法によれば、地下の飽和帯（２）と不飽和帯（３）の境界部周辺に沿って広域流体路層（１）を設置すると、該広域流体路層（１）は所定の層厚で面状に広がると共に、その全体に亘って互いに連通する数多の間隙により優れた流体通過性を発揮する。
【００３８】
前記広域流体路層（１）は、互いに連通し合って三次元的に拡がるような数多の間隙を含み、これらの間隙が広域流体路層（１）の全表面に亘って外部に開口するものであれば、どのような形態としても良いが、具体的には前記［２１］に記載のように、例えば砕石、砂礫等の粒状物を、所定範囲で密に集合させた状態に積層して成るものとすれば、極めて容易に設置することができる。
【００３９】
このような広域流体路層（１）を通じることで、流体の注入およびまたは流体の回収による流体制御を、地下のより広い範囲で多数の井戸を設けることなく実施することが可能となり、多大なコストアップを招くことなく、広い範囲の土壌および地下水から効率良く汚染物質を除去することができる。
【００４０】
前記広域流体路層（１）は、その全面にスクリーン機能を有するものであり、広域流体路層（１）の上面部では、気体をより効率良く回収する機能を実現できると共に、広域流体路層（１）の下面部では、滲出した地下水をより効率良く回収する機能を実現できることにより、流体としての汚染物質の回収、並びに汚染対策に必要な流体の注入を可能とする。
【００４１】
特に従来技術による流体の注入および回収は、いわば点または線状に例えられるが如く実施されていたのに対し、本発明に係る土壌汚染対策方法による広域流体路層（１）を用いた流体の注入およびまたは回収は、面状に実施されるものであり、流体の注入およびまたは回収の効率を、従来技術に比して格段に高めることが可能となる。
【００４２】
しかも、前記広域流体路層（１）を通じた流体制御によって、広域流体路層（１）以深に存する汚染物質が広域流体路層（１）以浅の土壌へ拡散することを防止することができ、また逆に、広域流体路層（１）以浅に存する汚染物質が広域流体路層（１）以深の土壌へ拡散することも防止することができる。加えて、前記広域流体路層（１）を通じて多様な流体流の操作により、前述した汚染拡散の防止を更に強化することが可能である。
【００４３】
特に従来技術の一般的な修復過程において、不飽和帯（３）の処理を先行し飽和帯（２）の処理を後の工程としている場合等には、飽和帯（２）に存する地下水汚染が毛細管現象等で上部の不飽和帯（３）に浸潤し、汚染拡散による再汚染を引き起こす可能性があったが、本土壌汚染対策システムによれば、広域流体路層（１）を飽和帯（２）と不飽和帯（３）との間に区画するように設置することにより、毛細管現象による再汚染を防止することもできる。
【００４４】
また、前述したように広域流体路層（１）の上面部では、気体をより効率良く回収する機能を実現でき、広域流体路層（１）の下面部では、滲出した地下水をより効率良く回収する機能を実現できるので、前記［２］に記載のように、広域流体路層（１）を通じて、流体である気体と液体の回収を並行して行うことにより、汚染処理の効率化を図ることが可能である。特に、前記飽和帯（２）には主として気体を、そして不飽和帯（３）では主として液体を対象とした流体制御を同時に実施することにより、いっそう迅速な汚染処理が可能となる。
【００４５】
また、前記［３］に記載のように、地層構造を有しない汚染土壌を前記広域流体路層（１）上に積層させた後、前記広域流体路層（１）を通じて流体制御を行うことにより、従来技術のように汚染された自然地層に多数の井戸を配置することなく、自然の地層構造を破壊した汚染土壌に対して、広域流体路層（１）を利用した一元的な流体制御による汚染処理が可能となる。
【００４６】
また、前記［４］に記載のように、汚染土壌を汚染濃度別に区域を指定して前記広域流体路層（１）上に積層させた後、前記区域毎に汚染濃度に応じた前記広域流体路層（１）を通じての流体制御により、例えば、汚染濃度が高い区域では流体吸引を局所的に高める等と、緩急をつけての効率的な汚染処理が可能となる。ここで流体吸引を局所的に高めるためには、例えば、当該区域に後述する前記［１８］に記載の補助構造物（５）を形成すれば良い。
【００４７】
また、前記［５］に記載のように、汚染土壌を混合し汚染物質濃度を平均化する操作、または客土を混入し更に汚染物質濃度を低くして平均化する操作を行った後、前記広域流体路層（１）を通じての流体制御を行えば、高濃度の汚染されている土壌からも効率良く汚染物質を除去することが可能となる。これは、高濃度の汚染がもたらす修復律速要因として、微生物の代謝反応阻害や気体との接触面が少ないこと等が主因と考察されることに基づき知見された方法である。
【００４８】
また、前記［６］に記載のように、前記広域流体路層（１）の内部ないし周囲に難透過性壁（３１，３２）を設置し、該難透過性壁（３１，３２）により土壌間隙の連続性を一部遮断することにより、広域流体路層（１）を通じての流体制御における流体流を所望の方向に誘導することができ、また、特に流体の回収時における気密性が高まることで吸引効果を向上させることも可能となる。なお、難透過性壁（３１，３２）の代わりに遮水壁（３０）を設置するようにしても良い。
【００４９】
また、前記広域流体路層（１）を通じての流体制御には、様々なバリエーションが考えられるが、例えば前記［７］に記載のように、広域流体路層（１）を通じての流体制御により、飽和帯（２）に地下水循環系を形成すれば、かかる地下水循環系に含まれる汚染物質を地下水と共に効率良く回収することが可能となる。
【００５０】
ここで前記［８］に記載のように、地下水系を酸化雰囲気下に保つことにより、いっそうと汚染処理の効率化を図ることが可能となる。地下水系を酸化雰囲気下に保つには、地下水系に分子状酸素や過酸化物を添加すると良い。具体的には例えば、空気やオゾンの散気を利用することが最適である。
【００５１】
酸化雰囲気下に保たれた地下水系は、好気性微生物の生育に適する環境となり、前記［９］に記載のように、地下水系にて好気性微生物の好気的代謝を利用した水処理を併せて行うことにより、更に迅速に汚染浄化を行うことができる。また、オゾン等の通気負荷量を変化させることにより、微生物の現存量を制御したり、また浄化後には利用生物を殺菌する等、目的に応じて酸化状態を変化させることにより、運転や管理に優れた汚染浄化を行うことができる。
【００５２】
一方、前記［８］に記載の場合とは逆に、前記［１０］に記載のように、地下水系を還元雰囲気下に保つことによっても、汚染処理の効率化を図ることが可能である。地下水系を還元雰囲気下に保つには、地下水系に還元鉄粉や糖、アルコール等の還元性物質を添加すると良い。
【００５３】
還元雰囲気下に保たれた地下水系は、嫌気性微生物の生育に適する環境となり、前記［１１］に記載のように、地下水系にて嫌気性微生物の嫌気的代謝を利用した水処理を併せて行うことにより、前記［９］に記載の場合と同様に迅速な汚染浄化を行うことができる。また、微生物集塊中では周囲が酸化雰囲気下である場合でも、局所的に嫌気性微生物の生育に適する環境が整う場合もあり、この様な現象を利用した酸化／還元の複合的な汚染処理を同時に図ることも可能である。
【００５４】
これら酸化／還元雰囲気の条件設定においては、特に自然地質の酸化／還元状態と同様の雰囲気をその条件として選択することが望ましい。一方、条件を違えて実施する場合には、酸化還元の境界面にて沈澱物等を生成し地層の目詰まりを誘因して後の処理に支障をきたす可能性も示唆される。実施においては、対象となる汚染種や自然地質条件を良く吟味し、その都度に条件を選択することにより、運転や管理に優れた汚染浄化を行うことができる。
【００５５】
また、前記［１２］に記載のように、地下水の一部を、地上に設置した汚染処理装置（２３）を通じて浄化処理し、該汚染処理装置（２３）で処理した地下水を再び地下水系に戻すことにより、地下水を極力無駄にすることなく繰り返し有効活用すると共に、該地下水中の汚染物質を十分に除去することが可能となる。
【００５６】
また、前記［１３］に記載のように、地表部と飽和帯（２）下部より非汚染水あるいは低濃度汚染水等の液体を注入し、これらの液体を前記広域流体路層（１）にて回収する流体流を形成することで、前記飽和帯（２）および前記不飽和帯（３）に存する汚染物質を除去しても良く、あるいは、前記［１４］に記載のように、地下水面下より散気を行い、前記広域流体路層（１）を通じての吸気により、散気気体と共に汚染物質を回収することもできる。
【００５７】
また、汚染物質が非水液溜（ＮＡＰＬ）の状態で存在する場合には、前記［１５］に記載のように、土壌中の汚染物質の気化を促す操作と共に、前記広域流体路層（１）を通じての吸気により、気化を促し汚染物質を回収すると良い。
【００５８】
ここで、水より比重が重い汚染物質が重非水液溜として飽和帯（２）の基底部に存在し、該基底部からその下方の不透水層への汚染物質の浸潤が顕著な場合には、前記［１６］に記載のように、汚染物質の気化を促す操作を、加熱した過酸化物溶液を土壌中に注入することにすれば、水よりも比重の重い過酸化物を含む加熱溶液は不透水層に浸潤し、この加熱溶液の酸化に伴う反応熱により、重非水液溜の揮発による気化を促すことができ、広域流体路層（１）の下面部を通じた吸気により、揮発した汚染物質を確実に回収することができる。
【００５９】
また、前記［１７］に記載の土壌汚染対策方法によれば、前記広域流体路層（１）に、その上下面部の何れか少なくとも一方より略垂直方向に突出し、広域流体路層（１）と同様に互いに連通する数多の間隙を含み、該広域流体路層（１）に連通する凸様の補助構造物（５）を併せて形成したことにより、特に補助構造物（５）の周囲にて、前記広域流体路層（１）を通じての流体の注入および回収を局所的に強化することができる。
【００６０】
また、前記［１８］に記載の土壌汚染対策方法によれば、前記広域流体路層（１）の周囲を囲む遮水壁（３０）を地下に設置し、前記補助構造物（５）を、広域流体路層（１）の上面部周囲にて遮水壁（３０）の内側壁と一部または全面が接するように形成する。
【００６１】
そして、前記遮水壁（３０）の外側周囲にて自然地下水位が最も高い地点にある遮水壁（３０）の一部を外側と連通可能に開放すること、または遮水壁（３０）内側に液体を注入することで、前記補助構造物（５）内における地下水位を、前記遮水壁（３０）の外側周囲における自然地下水位の最高位と略同位かそれ以上の高位に保つように設定する。このような遮水壁（３０）の内外の水位差によって、該遮水壁（３０）の外側周囲に存する汚染物質の内側への滲入を防ぐことが可能となる。
【００６２】
さらにまた、前記［１９］に記載したように、前記広域流体路層（１）を難透水ないし遮水施工で仕切ることで、地下で互いに連通可能に区画された複数の反応部を形成し、これらの各反応部に一連の流体流を通過せしめることにより、前記各反応部が連結して成る汚染処理系を構築すると良い。
【００６３】
このように遮水壁（３０）あるいは難透過性壁（３１，３２）を適宜選択したり組み合わせて、地下に複数の反応部を形成すれば、これらの各反応部を一連の流体流によって通過せしめる流体制御を行うことにより、多様な操作や反応系を組み合わせた汚染処理系を構築することができ、更に汚染浄化を迅速に実施することも可能となる。
【００６４】
以上のような本発明に係る土壌汚染対策方法は、前記［２０］に記載の土壌汚染対策システムによって、なるべく簡素にかつ効率良く実施することができる。すなわち、本土壌汚染対策システムは、前述した広域流体路層（１）と、この広域流体路層（１）に地上より連通可能に設置した井戸様構造体（１０）とを有するものであり、井戸様構造体（１０）により広域流体路層（１）を通じて、該広域流体路層（１）の周囲に対する流体の注入、および該広域流体路層（１）の周囲からの流体の回収の少なくとも何れか一方による流体制御を実施することができる。
【００６５】
ここで井戸様構造体（１０）は、例えば前記［２４］に記載のように、地中に連通するストレーナ部（１１）を軸方向に複数設けて構成し、各ストレーナ部（１１）の少なくとも１つを、前記広域流体路層（１）に連通する位置に配置させれば、井戸様構造体（１０）により広域流体路層（１）を通じて多様な流体制御を実施することが可能となる。
【００６６】
また、前記［２１］に記載の土壌汚染対策システムによれば、前述したように広域流体路層（１）を、所定範囲で粒状物を密に集合させた状態に積層して成るものとすることで、該広域流体路層（１）を極めて容易に設置することができる。
【００６７】
また、前記［２２］に記載の土壌汚染対策システムによれば、前記広域流体路層（１）に、その上下面部の何れか少なくとも一方より略垂直方向に突出し、広域流体路層（１）と同様に粒状物を密に集合させた状態で数多の間隙を含み、該広域流体路層（１）に連通する凸様の補助構造物（５）を併せて形成したことで、前記［１８］の場合と同様に、補助構造物（５）の周囲にて流体の注入および回収を局所的に強化可能なシステムを構築することができる。
【００６８】
また、前記［２３］に記載の土壌汚染対策システムによれば、前記補助構造物（５）に、汚染物質の吸着または分解を促進する材質を含ませることにより、補助構造物（５）から回収する流体中の汚染物質を積極的に吸着したり、あるいは分解により無害化しながら回収することが可能となり、汚染物質の除去を更に促進させることができる。なお、コスト低減の観点から、局所的な補助構造物（５）にのみ汚染物質の吸着または分解を促進する材質を含ませる他、広域流体路層（１）を成す粒状物にもこれらの物質を含ませても良い。
【００６９】
また、本土壌汚染対策システムにより、前記［７］に記載の地下水循環系を形成すると共に、前記［９］に記載のように、好気性微生物の好気的代謝を利用した水処理を併せて行う場合には、地下水循環の駆動源となるポンプ（４０）の集水部における増殖微生物による閉塞を防止するための工夫にシステムに組み込む必要がある。
【００７０】
そこで、前記［２５］に記載した構成を組み込むことにより、前記ポンプ（４０）の稼動に伴いその集水部を覆うストレーナ（４２）表面に蓄積した濾過物を、給気経路（１７）からの通気により剥離し、この剥離した濾過物を濾過物回収経路（４３）により通気気体と共に地上に回収することで、前述したように微生物を用いた地下水汚染処理を併せて実施しても、微生物等を含む汚泥による閉塞を確実に防止することができる。
【００７１】
【発明の実施の形態】
以下、図面に基づき本発明を代表する各種実施の形態を説明する。
図１〜図１１は、各種の実施の形態に係る土壌汚染対策方法および土壌汚染対策システムを示している。
図１および図２は、広域流体路層の代表的な設置例を示している。この広域流体路層１は、地下の飽和帯２と不飽和帯３の境界部周辺に人工地層を形成するように設置される。
【００７２】
広域流体路層１は、所定範囲で略水平方向に展開され、粒状物を密に集合させた状態に積層して成り、互いに連通する数多の間隙を含む人工地層である。ここで粒状物とは、具体的には例えば、砕石、砂礫等が該当するが、自然物に限られるものではなく人工的な球体等であっても良い。
【００７３】
広域流体路層１は、互いに連通し合って三次元的に拡がるような数多の間隙を含み、これらの間隙が広域流体路層の全表面に亘って外部に開口するものであれば、どのような形態としても良い。他に例えば、数多の間隙を含むブロックを敷き詰めて形成したり、あるいは比較的狭い範囲に設置するような場合には、数多の間隙を含む所定厚のシート層として形成することも可能である。
【００７４】
また、飽和帯２とは、一般には地下水面Ｗより下位で、土壌間隙が水分で飽和状態である土壌帯であり、不飽和帯３とは、一般には地下水面Ｗより上位で、土壌間隙中の水分が不飽和状態であって気体が混じっている土壌帯である。なお、飽和帯２の下方には、基盤岩や粘土層等の不透水層Ｒがある。
【００７５】
飽和帯２と不飽和帯３との境界である地下水面Ｗを含む境界部周辺に、広域流体路層１を設置することで、この広域流体路層１を通じての流体制御は、飽和帯２に存する地下水と、不飽和帯３に存する地下空気の両方を対象とすることができる。本発明に係る土壌汚染対策方法は、広域流体路層１を通じて、該広域流体路層１の周囲への流体の注入、および該広域流体路層１の周囲からの流体の回収の少なくとも何れか一方による流体制御を行うものである。
【００７６】
広域流体路層１の設置する場所である飽和帯２と不飽和帯３は、地下水面Ｗを上下間に含んだ所定の層厚で平面的に広がりを持つ自然的空間区分であるが、この区分は自然界に存在するままの状態に限られるものではない。例えば、遮水工等で汚染対策対象区域の周囲を囲むことで遮水等を実施する等、飽和帯２と不飽和帯３との区分を人為的に設定する、すなわち、地下水面Ｗの高さを任意に設定できるような場合は、汚染対策上人為的に設定した各帯区分を適用して、その境界部周辺に広域流体路層１を設置することになる。地中への注水／揚水により、不飽和帯３と飽和帯２との区分を人為的に設定するような場合も同様である。
【００７７】
広域流体路層１の施工に際しては、先ず汚染対策対象地で施工区域内の不飽和帯３並びに飽和帯２上層部の土壌を掘削した後、砕石、砂礫等を敷き込み、必要に応じた層厚まで積層させる。この時、広域流体路層１の上下面部に用いる砕石や砂礫等は、広域流体路層１の中間部のそれとは粒度を違えて設置し、広域流体路層１の周囲にある土壌の流体路層中への侵入を防ぐようにすると良い。
【００７８】
同じ目的で、網目を有するシート等で広域流体路層１の上下面や側部を覆うことで代用しても良い。すなわち、流体を透過しつつも土壌の侵入を防ぐ方法にて広域流体路層１を覆うものであれば、前記事例に限定されるものではない。広域流体路層１の設置完了後、その上部を覆土４する。なお、広域流体路層１の基本形状は、図２に示した直方体形状に限定されるものではなく、汚染対策対象地の状況等によってその都度適切な形状に設定する。
【００７９】
また、広域流体路層１には、その上下面部の何れか少なくとも一方より略垂直方向に突出し、広域流体路層１と同様に粒状物を密に集合させた状態で数多の間隙を含み、該広域流体路層１に連通する凸様の補助構造物５を併せて形成しても良い。補助構造物５により、その形成部位の周囲にて、前記広域流体路層１を通じての流体の注入および回収を局所的に強化することができる。
【００８０】
補助構造物５の形状については、円筒状、帯状、逆杯状等と様々な形状に形成することができ、特に限定されるものではない。また、補助構造物５の設置位置や数も特に限定するものではない。なお、補助構造物５について詳しくは後述する。
【００８１】
図１〜図３に示すように、第１実施の形態に係る土壌汚染対策システムは、前述した広域流体路層１と、地上より広域流体路層１に連通可能に設置した井戸様構造体１０とを有して成る。本土壌汚染対策システムは、この井戸様構造体１０により広域流体路層１を通じて、該広域流体路層１の周囲に対する流体の注入、および該広域流体路層１の周囲からの流体の回収のうち、少なくとも何れか一方による流体制御を実施可能に構成されている。
【００８２】
前記井戸様構造体１０は、地中に連通する開口部であるストレーナ部１１ａ，１１ｂを軸方向に複数設けて成り、各ストレーナ部１１ａ，１１ｂの少なくとも１つは、前記広域流体路層１に連通する位置に配置される。図１〜図３に示す設置例では、上側のストレーナ部１１ｂが広域流体路層１に連通して、該広域流体路層１との間で流体の出入りが可能となっている。なお、所望する流体制御の形態によっては（例えば図３に示す場合等）、井戸様構造体１０の途中に１カ所だけストレーナ部１１を設ければ足りる場合もある。
【００８３】
井戸様構造体１０により、吸引による流体の回収を実施する場合には、ストレーナ部１１ａ，１１ｂを除いて井戸様構造体１０の内部を気密にできる機能を必要とする。その際、井戸様構造体１０の下端口等と土壌との接触面においては、吸引の妨げとならないようにベントナイト等で隙間を満たすシーリング１２を施す。
【００８４】
加えて、後述の地下水循環等を実施する場合（例えば図４に示す場合等）、井戸様構造体１０の軸方向に複数のストレーナ部１１ａ，１１ｂを設けることが必須となり、井戸様構造体１０の内部をパッカー１３によって、各ストレーナ部１１ａ，１１ｂに対応する部位毎に区画し、各ストレーナ部１１ａ，１１ｂ間を結ぶ配管とポンプ等の集水手段を通じた循環系を構築する。
【００８５】
すなわち、本土壌汚染対策システムは、前記井戸様構造体１０の内部に挿通されて構造体内部と地上設備とを繋ぐ配管と、該配管に連結するポンプ等の付帯設備を備えており、これらの付帯設備によって、井戸様構造体１０を介した地上設備と前記広域流体路層１との間での流体の回収／注入を実施可能に構成される。
【００８６】
また、本土壌汚染対策システムの主たる付帯設備として、図１に示すように、流体移送を目的とした真空ポンプ２１や液体搬出ポンプ２２、汚染処理装置２３等が挙げられ、流体受槽２４等と共に本土壌汚染対策システムを利用した汚染対策に用いられる。
【００８７】
前記汚染処理装置２３としては、具体的には例えば、曝気塔、活性炭吸着塔、樹脂／担体充填槽、酸化分解槽、油水分離槽、膜分離／濾過槽、凝集沈澱槽、好気処理槽、ブラウンガス処理槽等が該当する。更に、流体の供給（注入）に関する付帯設備としては、ボイラー、コンプレッサー、有機物供給タンク、塩類供給タンク、溶媒供給タンク等が挙げられる。
【００８８】
このような本土壌汚染対策システムを構成する付帯設備は、前述した装置等に限定されるものではなく、汚染種や状態によってその都度適切に選定される。なお、井戸様構造体１０の広域流体路層１での設置数、大きさは特に規定するものではないが、従来技術の如く必ずしも多数本を設ける必要がなく、広域流体路層１の大きさや地下水循環方法等に応じて、必要最低限の本数および大きさに設定すれば良いことは言うまでもない。
【００８９】
図３は本発明の第１実施の形態を示している。
本実施の形態では、不飽和帯３において、汚染物質の拡散方向とは逆行する気体を主とした流体流Ａを、広域流体路層１と井戸様構造体１０を通じた吸引により形成し、飽和帯２から不飽和帯３への汚染拡散を防止する。また併せて、井戸様構造体１０を利用した揚水にて地下水位を管理し、地下水位の季節変動等に起因する一時的な水位上昇等による不飽和帯３への汚染拡散を防止する。
【００９０】
すなわち、井戸様構造体１０において、広域流体路層１と通じるストレーナ部１１ｂの下端を、自然地下水位より低く、かつ広域流体路層１の下面よりも高い位置に設置し、井戸様構造体１０内に嵌挿させた吸引管１４の吸引部位を、前記ストレーナ部１１ｂの下端より低い位置に設置することで、該吸引管１４からの吸引により、飽和帯２の汚染物質を回収する地下水流Ｂを形成する。そして、前記液体搬出ポンプ２２の駆動により井戸様構造体１０を介して回収された地下水は、前記汚染処理装置２３によって無害化処理される。
【００９１】
一方、広域流体路層１の上方の不飽和帯３に汚染物質が存在する場合には、前述したのと同様の地下水の流体制御により、広域流体路層１の下方の飽和帯２への汚染拡散防止を図る際に適用することも可能である。すなわち、不飽和帯３より下方向に拡散する汚染物質は、広域流体路層１を通じた吸引により形成される気体を主とした流体流Ａによって、その一部が気体として回収され、また、浸透水等と共に広域流体路層１中に滲入した汚染物質は、地下水流Ｂによって地下水面Ｗ近傍で回収される。
【００９２】
それにより、不飽和帯３に存在する汚染物質は、飽和帯２の深部に拡散する前に、広域流体路層１を通じて井戸様構造体１０により回収され、前記汚染処理装置２３によって無害化処理される。なお、これらの汚染拡散を防止する方法は、図３で説明した事例に限定されるものではなく、広域流体路層１を通じて多様な流体流を形成し、拡散する汚染をこの流体流に誘導し回収する方法であれば良い。
【００９３】
ところで、本実施の形態では、前記広域流体路層１の施工上、不飽和帯３の掘削は必須であるが、この掘削後の上部への覆土４に用いる土壌に関しては、基本的にはその履歴を問わない。仮に掘削した土壌の汚染状況が、単に流体の回収／注入のみでは汚染処理が困難な場合には、別途に汚染処理を施した後に覆土４として用いても良いし、別途の非汚染土壌をいわば客土として覆土４に用いても良い。
【００９４】
また、汚染処理を施したものの汚染処理完了までに時間経過を要する処理過程にある土壌の場合には、例えば、好気性微生物を用いたバイオレメディエーションや反応熱を利用した汚染の脱着処理等を施した土壌において、その処理過程で流体の回収や注入を必要とする場合には、本発明の広域流体路層１とこれを通じての流体制御による汚染修復／管理を行うことが好ましい。一方、掘削した土壌の汚染状況が、単に流体の回収／注入のみで汚染処理が可能な場合は、掘削土壌をそのまま埋め戻し、以後同様に本実施の形態を利用した汚染修復／管理を実施する。
【００９５】
前述したように、広域流体路層１の施工に伴い不飽和帯３の掘削は必須であり、その後の覆土４によって、広域流体路層１の上方には内部に地層構造を有さない覆土層が形成される。この地層構造を有さないことが、かえって流体の回収／注入による汚染修復において、流体の吸引に有利であることが実験によって明らかとなった。すなわち、従来の汚染対策として、汚染された自然地層毎に多数配置していた吸引／注入井戸を、自然地層構造を破壊することで広域流体路層１を利用した一元的な吸引により対応可能となった。
【００９６】
この際、流体の回収／注入量を部分的に強化できる凸様の前記補助構造物５を広域流体路層１の上面と通じるように形成することで、汚染状況に応じた修復が可能であることを実験による検討で明らかとした。すなわち、掘削土のロット別に汚染濃度を把握し、広域流体路層１上にて汚染濃度別に区域を指定して覆土４の埋め戻しを行い、汚染程度に応じて前記補助構造物５を形成することで、当該周囲における汚染処理を集中的に強化して行うことができ、より効率的な修復が可能である。
【００９７】
補助構造物５は、スクリーン機能を一部ないし全面に有し、外部土壌の内部への侵入を防ぐと共に、流体の通過を可能とする構造に形成されるものである。かかる構造であれば、形状、材質等は特に問うものではない。また、補助構造物５の内部は、スクリーン機能を損なわない程度に砕石や砂礫等を充填し構造物の形状を保つようにするが、充填物についても構造物の形状の保持が可能であれば、特に砕石や砂礫等に限定されるものではない。また前述したが、補助構造物５の形状や設置数も特に限定されるものではなく、広域流体路層１の上下面部の何れかと接して、流体流を内部に形成できるものであれば足りる。
【００９８】
補助構造物５には、汚染物質の吸着または分解を促進する材質を含ませることにより、補助構造物５から回収する流体中の汚染物質を積極的に吸着したり、あるいは分解により無害化しながら回収することが可能となり、汚染物質の除去を更に促進させるとができる。具体的な物質としては、例えば、粒状に成形した炭化生成物や粒状物にまぶす還元鉄粉等が挙げられる。いわゆる炭に代表される炭化生成物は、汚染物質の吸着する作用を備えており、還元鉄粉は、時間を有するがトリクロロエチレン等の有機塩素化合物の脱塩素化を図る弱い処理能を有することが知られている。
【００９９】
また、不飽和帯３の土壌が高濃度の汚染されている汚染対策対象地で、流体の吸引により汚染処理を行う場合には、汚染濃度を適切とするために汚染濃度を低く均一となるような汚染分散処理を前処理として併せて実施すると良い。この汚染分散処理の具体的な方法としては、例えば、前記広域流体路層１の施工後に覆土４する際に、この覆土４に係る汚染土壌を混合し汚染物質濃度を平均化する操作、または客土を混入し更に汚染物質濃度を低くして平均化する操作が有効となる。
【０１００】
汚染分散処理としての前記各操作は、高濃度の汚染がもたらす修復律速要因として、微生物の代謝反応阻害や気体との接触面が少ないこと等が主因と考察されることに基づき知見されたものであり、このような汚染分散処理後に、前記広域流体路層１を通じての流体制御により、前記汚染土壌中の汚染物質を除去することで、より迅速な汚染処理が可能となる。なお、汚染分散処理としての前記各操作は、流体制御の前処理のみにとどまることなく、生物／化学的処理や物理的処理を実施する場合にも利用可能な技術と示唆される。
【０１０１】
続いて、広域流体路層１および井戸様構造体１０と、その付帯設備から成る土壌汚染対策システムを用いた流体制御による土壌汚染対策方法について、各汚染物質の土壌汚染機構の類似性に則って汚染を分類し、各々の汚染対策に適した土壌汚染対策方法を詳細に検討した結果、以下の実施の形態に係る新たな土壌汚染対策システムおよび土壌汚染対策方法を提案するに至った。以下、各々の汚染に最適な各種実施の形態について詳細に説明する。
【０１０２】
土壌中に含まれる汚染のうち、特に汚染拡散性が見られる汚染は、大きく分けて次の３つの汚染群に大別できる。その一つは、水に対する溶解度が比較的低く水より比重が軽い「軽非水液性汚染」であり、ベンゼン、エチルベンゼン、トルエン、キシレン、多環芳香族化合物等を含む、ガソリン等に代表される炭化水素系混合物によるものが代表的な軽非水液性汚染として知られる。
【０１０３】
これらの軽非水液性汚染は、不飽和帯３での地下浸透過程において地下空気並びに地層を汚染した後、地下水面Ｗに到達後は地下水流に乗じて水面にて移動拡散し下流域に汚染を拡散させるものである。
【０１０４】
一方、水に対する溶解度が比較的低く水より比重が重い「重非水液性汚染」が知られ、主に有機塩素系溶剤によるものが多い。具体的には、テトラクロロエチレン、トリクロロエチレン、ｃｉｓ−１，２−ジクロロエチレン、ｔｒａｎｓ−１，２−ジクロロエチレン、１，１−ジクロロエチレン、ビニルクロライド、塩化メチル、ジクロロメタン、クロロホルム、四塩化炭素、１，１−ジクロロエタン、１，２−ジクロロエタン、１，１，１−トリクロロエタン、１，１，２−トリクロロエタン等が重非水液性汚染にて確認されている。また、汚染事例は少ないが、１，３−ジクロロプロペン、１，２−ジクロロプロパン、クロロベンゼン、ジクロロベンゼン等も、重非水液性汚染を誘発する可能性が示唆される。
【０１０５】
これらの重非水液性汚染は、不飽和帯３での地下浸透過程において地下空気並びに地層を汚染した後、地下水面Ｗ付近に到達しその一部が水面にて重非水液溜を形成し、その一部が更に飽和帯２の下部に移行する際に地下水流に乗じて溶解後移動拡散し、そしてその一部が飽和帯２の基底部まで達し重非水液溜を形成して、地下水中に汚染を徐放し下流に汚染拡散をもたらすものである。
【０１０６】
更にまた、水に対する溶解度が比較的高く、かつ土壌への吸着が少ない汚染として、硝酸態窒素類と一部のシアン、砒素、重金属化合物類等の汚染も知られている。これらの汚染は、雨水の不飽和帯３での地下浸透過程で溶解浸潤し地下水面Ｗに達した後、地下水流に乗じて移動拡散するものである。
【０１０７】
図４は本発明の第２実施の形態を示している。
図４における井戸様構造体１０の紙面右側に、軽非水液性汚染を汚染対策対象とした場合の広域流体路層１の設置例と、これを通じての流体流向の代表的な例を示す。軽非水液性汚染による汚染では、広域流体路層１と通じる井戸様構造体１０の上側のストレーナ部１１ｂの下端を、自然地下水位より低く、かつ広域流体路層１の下面よりも高い位置に設置する。
【０１０８】
井戸様構造体１０内の吸引管１４の吸引部位は、前記ストレーナ部１１ｂの下端より低く設置し、汚染地下水、汚染地下空気の他、地下水面Ｗ上に浮かぶ軽非水液溜Ｎ１を吸引管１４にて回収する。これら汚染は、井戸様構造体１０を介して回収された後、前記汚染処理装置２３によって無害化処理される。また、井戸様構造体１０の下側のストレーナ部１１ａからは、注入管１５を介して洗浄用水Ｋを注入し、汚染水を上方の広域流体路層１へ導く地下水流Ｃを形成させる。
【０１０９】
ここで、前記広域流体路層１の側部に沿って遮水壁３０を設置すると共に、該遮水壁３０との間に所定のすき間を開けた状態で、前記広域流体路層１の下面部に沿って難透過性壁３１を仕切り状に設置することで、土壌中の所定方向における連続性を遮断、あるいは透過しにくい状態とする。それにより、前記広域流体路層１を通じての流体制御における流体の流れ方向を誘導することができ、また、特に流体の回収時における気密性を高めることで吸引効果を向上させることが可能となる。
【０１１０】
また、前記洗浄用水Ｋは、汚染が認められないものが望ましいが、少なくとも汚染地下水よりも汚染が軽微であれば、洗浄用途として利用可能であり、汚染処理装置２３を経た処理水の一部を再び洗浄用水Ｋとして用いて、地下水循環系を構築しても良い。また、洗浄効果を高めるために、洗浄薬液を加えたものを用いても良い。
【０１１１】
前記広域流体路層１を通じての流体制御により、不飽和帯３に存する揮発性の汚染物質は、地表から広域流体路層１の上面部に向かって流れる地下空気流Ｄに移相し、広域流体路層１の上部を通過して井戸様構造体１０の上側のストレーナ部１１ｂに向かい、このストレーナ部１１ｂより井戸様構造体１０内に到達した後、最終的に地上設備に回収されて除去される。
【０１１２】
一方、自然地下水面Ｗに存在する軽非水液溜Ｎ１は、井戸様構造体１０内における水位を自然地下水位より低く保つことで、地下水と共に井戸様構造体１０内へ向かう水位勾配に従って寄せられて、井戸様構造体１０内に到達した後、最終的に地上設備に回収されて除去される。
【０１１３】
なお、前記吸引管１４とそれに連なる付帯設備によって実施される流体の回収は、各流体を回収できるシステムおよび方法であれば、前述した実施の形態に限定されるものではない。また、前記軽非水液性汚染による土壌汚染を、広域流体路層１を用いた流体制御によって汚染処理する方法は、広域流体路層１を通じた吸引操作を主たる流体操作とし、汚染流体を回収し除去する方法であれば良く、前述した実施の形態に限定されるものではない。
【０１１４】
加えて、前記軽非水液溜Ｎ１の汚染処理について詳細な検討を行った結果、広域流体路層１を通じての地下水の回収と空気吸引による滲出を図ることで、汚染された自然地層から効率の良い回収を図れることを明らかにした。
図４における井戸様構造体１０の左側紙面に、軽非水液溜Ｎ１を特に汚染対策対象とした場合の広域流体路層１の設置例と、これを通じての流体流向の代表的な例を示す。
【０１１５】
軽非水液溜Ｎ１の滲出を促すように、広域流体路層１の上下面部に沿ってそれぞれ難透過性壁３１を設置し、広域流体路層１を通じた流体の吸引を軽非水液溜Ｎ１が存在する自然地層区分６より実施する。滲出した軽非水液溜Ｎ１は、広域流体路層１の下部の地下水流を通じて、井戸様構造体１０にある上側のストレーナ部１１ｂより回収される。なお本方法は、軽非水液溜Ｎ１を有する自然地層に接するように広域流体路層１を設置し、吸引操作による軽非水液溜Ｎ１の滲出と地下水流による回収を流体制御として実施する方法であれば良く、前述した実施の形態に限定されるものではない。
【０１１６】
図５は本発明の第３実施の形態を示している。
本実施の形態は、地下水中の軽非水液性汚染に対する前記第２実施の形態以外の方法として、井戸様構造物１０の下側と上側に設けたストレーナ部１１ａ，１１ｂを介した地下水流を構築し、併せて地下水面下にて散気を並行して実施することで、汚染物質の気体への移相や微生物による好気的代謝等にて効率の良い汚染修復を実施するものである。
【０１１７】
図５に示すように、地下水流Ｃは基本的には図４の右面に示す場合と同様であるが、広域流体路層１中において地下水で満たされた飽和帯２の上側に散気管１６を設置し、地下水流を酸化雰囲気下の好気環境に設定する点で、図４の右面に示した前記第２実施の形態とは異なる。散気管１６は前記難透過性壁３１の直ぐ上側にて、上方に向けて散気するように設置されている。この散気管１６からの散気に用いる気体は、通常空気の他、分子状酸素を含むものであれば良く、他の共存ガスとしてオゾン等を必要に応じて添加する。
【０１１８】
散気管１６によって地下水中に散気された気体は、広域流体路層１中の気相で、広域流体路層１の上面部より吸引されてきた気体流と共に、井戸様構造体１０内の吸引管１４によって回収される。この回収気体は、その一部を再度散気に戻しても良いし、全量を前記汚染処理装置２３により適切な処理を施した後に大気開放としても良い。また、微生物の増殖を促すために、散気管１６を通じてアンモニアや亜酸化窒素等のガス状窒素源を、また窒素源等を含む養液を循環系内に供給しても良い。
【０１１９】
なお、散気方法は、図５の如く広域流体路層１中に設置されることが望ましいが、これに限定されるものではなく、既設の観測井戸等を二次利用し帯水層下部等から行っても良い。その場合は散気の広がる範囲を事前に想定し、その上部に十分な広がりを持つ広域流体路層１を設置する等して、汚染の拡散防止を心掛ける様にすると良い。
【０１２０】
井戸様構造体１０の下側のストレーナ部１１ａから飽和帯２中に注入された地下水は、広域流体路層１を通じて上側のストレーナ部１１ｂにて回収されるが、この回収された地下水を、図４に示す汚染処理装置２３で全量を適切な処理を施した後に地表にて放流しても良い。また、処理された地下水の全量またはその一部を、再度地下に戻し地下水循環系を構築しても良い。
【０１２１】
あるいは図５に示すように、井戸様構造体１０内をパッカー１３で区画した上下区分のうち、上側の区分に設置した水中ポンプ４０の稼動により、パッカー１３を貫通する給水管４１を通じて下側の区分に、前記回収された地下水の一部を給水し、下側の区分にあるストレーナ部１１ａより再び飽和帯２中に地下水を注入することで、再び地下水循環系を構築するようにしても良い。
【０１２２】
特に軽非水液性汚染溜Ｎ１（図４参照）が存在しない状況では、井戸様構造体１０を通じた吸気は気体吸引専用とし、地下水は水中ポンプ４０等を用いて、パッカー１３で仕切られた井戸様構造体１０の上側から下側の区画に移送することにより循環系を形成し、かかる循環系での微生物分解により汚染処理を行う。微生物分解により汚染処理は、特にベンゼン等の石油系炭化水素類の分解に適している。
【０１２３】
なお、地下にて循環系を構築する際には、循環系にて微生物の増殖を図る工程を含むことを考慮し、地下水の集水部における増殖微生物による閉塞に対する対策をシステムに組み入れる必要がある。すなわち、図５に示す本実施の形態においては、微生物量の制御を目的として前記散気管１６からのオゾンガスの散気量を図示省略した制御装置により適宜制御すると共に、井戸様構造体１０内に自動洗浄装置を設置している。この自動洗浄装置は、前記井戸様構造体１０の上側のストレーナ部１１ｂから集水された地下水を下側のストレーナ部１１ａより土壌中に注入する前記水中ポンプ４０の集水部４０ａにおける目詰まりを防止するものである。
【０１２４】
詳しく言えば自動洗浄装置は、前記水中ポンプ４０の集水部４０ａを、該集水部４０ａより集水される地下水を濾過するストレーナ４２で覆い、地上から通気可能な給気管（給気経路）１７を井戸様構造体１０内に挿通し、該給気管１７の下端出口を、前記集水部４０ａ側より前記ストレーナ４２内側を臨む位置に配置させ、地上まで連通する濾過物回収管（濾過物回収経路）４３を前記井戸様構造体１０内に挿通し、該濾過物回収管４３の下端に、前記ストレーナ４２を囲む状態で濾過物回収管４３と連通する大口径の回収部４４を接続して構成されている。
【０１２５】
給気管１７と濾過物回収管４３とは二重管構造に成っており、濾過物回収管４３は給気管１７を囲む外筒状に形成されている。また、水中ポンプ４０の集水部４０ａと前記給水管４１の接続口である排水部は、それぞれ井戸様構造体１０内において地下水面下に存在するように設置されている。
【０１２６】
通常の地下水循環運転時には、水中ポンプ４０の集水部４０ａを覆うストレーナ４２にて微生物集塊は濾過され、濾液たる地下水が井戸様構造体１０の下側のストレーナ部１１ａより飽和帯２に注入される。一方、時間経過と共に、水中ポンプ４０のストレーナ４２表面には微生物集塊が蓄積し、水中ポンプ４０の吸水性能を低下させ、水中ポンプ４０の負荷を上昇させる。
【０１２７】
この水中ポンプ４０における負荷が一定以上になった場合に、水中ポンプ４０の運転を図示省略した制御装置により自動停止させ、ストレーナ４２周囲での水の移動を一時遮断して、同時に地上より給気管１７を通じて水中ポンプ４０のストレーナ４２内側より圧縮空気等の気体の通気を行い、ストレーナ４２の外部表面に蓄積した微生物集塊を剥離する自動操作を行うように設定すれば良い。
【０１２８】
一方、給気管１７からの通気によって、ストレーナ４２の外側に移行した気体は、そのまま連通する大口径の回収部４４の内部で上方に向かうが、その過程で前記ストレーナ４２から剥離した周囲に漂う微生物集塊を含む地下水を巻き込みながら連通する大口径の回収部４４に連通する濾過物回収管４３を通って上方に向かう。最終的には、地上まで達した気体と剥離した微生物集塊を含む地下水を回収する。
【０１２９】
以上のような自動洗浄装置の自動運転により、微生物集塊は適切に処理され、前述した地下水の循環運転を連続的に安定して実施することが可能となる。なお、前記自動洗浄装置は、地下水循環運転において、微生物集塊等の濾過とそれを気体によって剥離する手段を有し、またその気体を用いて剥離した微生物集塊等を地上に回収する機能を有する一体型の自動運転システムであれば、前述した構成に限定されるものではない。また、地下水中の重金属や硝酸態窒素等の汚染を微生物に積極的に吸収させた後に、本装置を用いて地上に回収する別途の処理方法等への応用も可能であり、必要に応じて本装置の機能を活用すれば良い。
【０１３０】
また、本実施の形態のように、地下水系で散気を用いた好気条件にて汚染浄化を図る方法は、ベンゼン等の石油系炭化水素類に代表される軽非水液性汚染に限定されるものではなく、重非水液性汚染や硝酸態窒素等、多くの汚染種に対し有効な対策方法であることは既に実験により確認している。ただし、重非水液性汚染の場合は、微生物分解を図るよりも、散気による気体への移相を図り、この汚染を気体として回収を図る方法が適し、また硝酸態窒素類に関してはオゾン添加は行わず、他の逆洗や濾過処理の頻度を上げて閉塞対処を実施することで良好な処理が可能である。
【０１３１】
これまでに、軽非水液性汚染による汚染を対象とした場合の広域流体路層１を用いた各種流体制御による土壌汚染対策方法とそのシステムについて説明したが、続いて、重非水液性汚染による汚染を対象とした場合の土壌汚染対策方法とそのシステムについて、以下に順次説明する。
【０１３２】
重非水液性汚染による汚染も、概ね軽非水液性汚染による汚染と同様の流体制御にて対処することができる。ただし、汚染中心付近に位置する飽和帯２の基底周辺に重非水液溜がある区域では、別途周囲を遮水工等で仕切り、地下水を抜き取った後に、広域流体路層１を用いた流体制御を実施することで重非水液溜の回収を行う。
【０１３３】
重非水液溜が飽和帯２の基底部にあって、該基底部から不透水層Ｒへの汚染物質の浸潤が軽微な場合は、図６や図７に示すように、熱風Ｅや熱洗浄液Ｆ等による流体流を形成し、飽和帯２の基底部表面上の重非水液溜Ｎ２の揮発を促すと共に、流動性を高めた上で、広域流体路層１や凸様の補助構造物５を通じての流体制御により汚染対策を実施する。
【０１３４】
図６は本発明の第４実施の形態を示している。
本実施の形態は、熱風Ｅを用いた主に気体を中心とした流体操作を行うものであり、井戸様構造体１０内に熱供給管１８を挿通し、該熱供給管１８の下端出口を井戸様構造体１０の下側のストレーナ部１１ａがある区分まで延ばし、該熱供給管１８を介して、ストレーナ部１１ａより熱風Ｅを飽和帯２の土壌中に注入する。
【０１３５】
この熱風Ｅの注入により生じた熱気流により、重非水液溜Ｎ２の揮発を促し、凸様の補助構造物５やその上部が連なる広域流体路層１を通じた気体の吸引操作により、揮発した汚染物質を井戸様構造体１０の上側のストレーナ部１１ｂより回収する。吸引管１４を通って地上まで回収された汚染物質は、前記汚染処理装置２３等によって吸着または分解処理が施される。なお、本実施の形態では、広域流体路層１の周囲に沿って、地下水面Ｗより高い位置まで延びる遮水壁３０を設置している。
【０１３６】
図７は本発明の第５実施の形態を示している。
本実施の形態は、熱洗浄液Ｆを用いた主に液体を中心とした流体操作を行うものであり、井戸様構造体１０内に前記同様に熱供給管１８を挿通するが、該熱供給管１８の下端出口を井戸様構造体１０の上側のストレーナ部１１ｂがある区分までしか延ばさずに、代わりに前記吸引管１４の下端出口を下側のストレーナ部１１ａがある区分まで延ばしている。そして前記熱供給管１８を介して、上側のストレーナ部１１ｂより熱風Ｅではなく熱洗浄液Ｆを、広域流体路層１やその下面部より下方に延びる補助構造物５を介して飽和帯２の土壌中に注入する。
【０１３７】
この熱洗浄液Ｆの注入により生じた熱水流により、重非水液溜Ｎ２の回収を促し、井戸様構造体１０の下側のストレーナ部１１ａにおける揚水操作により、汚染物質を井戸様構造体１０の下側のストレーナ部１１ａより地下水と共に回収する。吸引管１４を通って地上まで回収された汚染物質は、前記汚染処理装置２３等によって処理される。
【０１３８】
熱供給管１８に供給する熱洗浄液Ｆの具体的な成分は、特に限定するものではないが、界面活性剤等の汚染を乳化し流体流による回収を促す成分の添加が望ましい。なお、本実施の形態でも、遮水壁３０を広域流体路層１の周囲に沿って、地下水面Ｗより高い位置まで延びるように設置しており、また、前記補助構造物５の一部は地下水面Ｗの内側壁と接している。
【０１３９】
一方、不透水層Ｒへの汚染物質の浸潤が顕著な場合は、水よりも比重の重い過酸化物を含む加熱溶液を汚染土壌に注入し、不透水層Ｒへの薬液の浸潤を図ると共に、酸化に伴う反応熱によって重非水液溜Ｎ２の揮発による気化を促し、広域流体路層１の下面部を通じた吸気により、揮発した汚染物質を気体として回収する方法が有効であり、また過酸化物として特に過酸化水素が適していることを実験により明らかにした。
【０１４０】
このような方法における流体制御の実施は、基本的には図６で説明した方法と同様であるが、熱風Ｅに替えて過酸化物を含む加熱溶液を断続的に注入する。以後、酸化に伴う反応熱によって、気化した重非水液物質を凸様の補助構造物５と広域流体路層１を通じた吸引によって回収することができる。
【０１４１】
また、前記過酸化水素を過酸化物の一例として説明したが、他に例えば、過マンガン酸、過硫酸等の過無機酸や、過酢酸等の過有機酸を成分として含む加熱溶液の利用が可能である。ただし、過酸化水素以外の利用は、汚染物質の気化よりはむしろ汚染物質の直接分解が主たる処理になる他、残成分による土壌閉塞、反応後の残成分の回収や洗浄等を必要とする等、全体操作は過酸化水素の場合と比べ煩雑となる。これらの使用は汚染対策地の状況に併せ、過酸化水素の使用が制限される場合等に代替として適用することが望ましい。
【０１４２】
また、前記薬液の注入においては、特に井戸様構造体１０を用いた注入に限らずとも、重非水液溜Ｎ２の存する飽和帯２の基底部に薬液を注入できる方法であれば良く、前述した第５実施の形態に限定されるものではない。なお、薬液による熱供給管１８の材質に対する影響等を考慮する必要があり、薬液に応じた注入方法を選択する必要がある。
【０１４３】
続いて、水への溶解性が高く土壌への吸着性が低い汚染物質、具体的には例えば、硝酸態窒素や一部の重金属等の汚染を対象とした場合の広域流体路層１を用いた各種流体制御による土壌汚染対策方法とそのシステムについて説明する。
【０１４４】
このような水への溶解性が高く土壌への吸着性が低い汚染物質に対しては、飽和帯２の下部と地表部からの注水と共に、広域流体路層１での吸気を並行して実施し、広域流体路層１へ汚染物質を誘導する運転や施工を取り入れる。また、界面活性剤、キレート剤、酸、アルカリ等の薬剤を用いて、土壌の汚染物質を水へ懸濁または抽出して処理を行う場合や、薬剤または微生物作用による重金属等のアルキル化等の官能基修飾等により汚染物質の水または気体への移行を促す処理を行う場合は、次のような実施の形態に係る方法により汚染処理が可能である。
【０１４５】
図８は本発明の第６実施の形態を示している。
本実施の形態では、地表部に設置した散水管１９を通じて、汚染物質を含まない水または薬剤溶液等の液体を不飽和帯３の上方より散水し、洗浄水の地下浸透による不飽和帯３の洗浄を実施すると共に、広域流体路層１を通じての吸引を実施し、前記洗浄水の地下浸透を促して洗浄効果を高めると共に、汚染気体の回収を行う。
【０１４６】
また、飽和帯２の洗浄は、井戸様構造体１０の上側または下側のストレーナ部１１ａ、あるいは１１ｂより洗浄水を土壌に注入し、図８において井戸様構造体１０を間にした左側に示す上部から下部へ、あるいは図８の右側に示す下部から上部へといった地下水流を形成して洗浄を実施する。
【０１４７】
この飽和帯２の洗浄にあっては、広域流体路層１の下面部より下方に延びる補助構造物５や、遮水壁３０および難透過性壁３１等を必要に応じて設置して、洗浄水の回収効率を高めた上で前記地下水流による洗浄を実施する。かかる洗浄過程において、地上に回収された洗浄排水は、その後に地上にて適切な汚染処理を施されるが、その処理された一部を再度洗浄水として再利用し、再び地下水系に供給するようにシステムを構築しても良い。特に薬剤等を用いた抽出処理を併せて行う場合は、汚染のみを除去して薬剤を含む溶液を再利用することで処理コストを低減することが可能となる。
【０１４８】
一方、前述した水への溶解性が高く土壌への吸着性が低い汚染物質のうち、微生物等により容易に分解されるものに関しては、前記した土壌汚染対策方法ばかりではなく、地下水循環系を形成する等して微生物代謝による物質変換を促す運転や施工を取り入れる工程も含めると良い。かかる工程は、図５で説明した軽非水性物質を酸化雰囲気下の地下水循環系により処理する方法と同様の措置にて対処できる。
【０１４９】
また、好気的な酸化雰囲気下ばかりでなく、嫌気的な還元雰囲気下においても広域流体路層１を通じての流体制御により、水への溶解性が高く土壌への吸着性が低い種々の汚染物質の分解が図れることを実験により確認した。すなわち、広域流体路層１を通じての流体制御により形成した地下水循環系において、嫌気的な還元雰囲気に設定し、このような環境下における汚染物質の分解について詳細な検討を行ったところ、次のような実施の形態に係る方法により、汚染処理が可能であることを明らかにした。
【０１５０】
図９は本発明の第７実施の形態を示している。
本実施の形態では、井戸様構造体１０の軸方向に所定間隔おきに３つのストレーナ部１１ａ，１１ｂ，１１ｃを設けたものを使用すると共に、難透過性壁３２や、還元物質含有部３３を適宜設置することで、流体制御により発生する流体流を所定方向に誘導している。
【０１５１】
井戸様構造体１０の内部は、各々のストレーナ部１１ａ，１１ｂ，１１ｃがある部位に応じて３つの区分にパッカー１３で仕切られており、地上の真空ポンプ２１から直接延びる吸引管１４の下端出口は、上側のストレーナ部１１ｂがある区分内で地下水位より上方に配されている。また、井戸様構造体１０内にて中央のストレーナ部１１ｃがある区分には、図５で説明した前記第３実施の形態と同様な自動洗浄装置を備えた水中ポンプ４０が設置されている。
【０１５２】
井戸様構造体１０内にて、中央の区分に設置された水中ポンプ４０の給水管４１は、下方に向かって延びパッカー１３を貫通して下側の区分に連通している。この下側の区分にも別の水中ポンプ４０が設置されており、該水中ポンプ４０の給水管４１は、上方に向かって延び２つのパッカー１３を貫通して上側の区分に連通している。
【０１５３】
地下水循環系は、井戸様構造体１０の中央のストレーナ部１１ｃより地下水を回収し、井戸様構造体１０内の中央の区分に設置された水中ポンプ４０を通じて、井戸様構造体１０内の下側の区分に送られる。この下側の区分に送られた地下水の一部は、井戸様構造体１０の下側の区分に設置された水中ポンプ４０によって、井戸様構造体１０の上側の区分まで送られ、上側のストレーナ部１１ｂを通じて広域流体路層１に注入され、残りの地下水は下側のストレーナ部１１ａから飽和帯２の土壌中に注入される。
【０１５４】
このような地下水の移動を繰り返すことによって、地下水循環系を形成する。かかる地下水循環系の流体流を所定方向へ誘導するために、広域流体路層１の下面部に沿うように難透過性壁３２を設置すると共に、広域流体路層１内の上部には、中心に位置する井戸様構造体１０の軸心に向かって逆円錐形に下方に傾斜するテーパを施した還元性物質含有部３３を設置している。
【０１５５】
本実施の形態における難透過性壁３２は、前記各実施の形態で説明した略水平な厚板状の難透過性壁３１とは異なり、外周縁より広域流体路層１内にて上方に立ち上がるフランジ部位３２ａを有している。還元性物質含有部３３は、地下水系を還元雰囲気下に保つための施工物であり、前述したように逆円錐形で広域流体路層１内にて前記難透過性壁３２に対向するように設置されている。なお、還元性物質には還元鉄粉や糖、アルコール等が該当する。
【０１５６】
また、前述した還元雰囲気下の地下水系にて嫌気性微生物の増殖を図るため、必要に応じて養液供給装置５０や養液供給槽５１を用いてアルコール等の増殖基質を広域流体路層１内に添加するようにして、本土壌汚染対策方法およびシステムによる汚染処理を促すように構成している。ここで増殖基質はアルコールに限定されるものではなく、微生物の増殖を図る炭素化合物であれば良く、汚染物質を効率良く代謝する微生物群を選択的に増殖させるために有用な炭素化合物であれば、より効果的な処理を図ることができる。
【０１５７】
発明者らの実験によれば、第７実施の形態に係る土壌汚染対策方法では、硝酸イオン等の水への溶解性が高く土壌への吸着性が低い汚染の他、地下水に溶解している軽非水液性汚染、重非水液性汚染に対しても有効であった。これらの汚染物質のうち、微生物の増殖基質と成り得るものを処理対象とする場合は、前述した増殖基質の補完たる添加を必要としない。
【０１５８】
必要に応じて、遮水壁３０や難透過性壁３２等を設置し、循環水回収の効率化を図った汚染処理や広域流体路層１上部での吸引を行う。なお、前述した嫌気還元雰囲気下での地下水循環を用いた土壌汚染対策方法に関しては、図９に示す実施の形態に限定されるものではなく、広域流体路層１の一部として還元性物質を含む部分を設置し、それを通じて嫌気的な還元雰囲気下で地下水循環系を形成し、加えて微生物代謝等によって汚染除去が図れるものであれば良い。
【０１５９】
また、微生物の増殖を促す地下水汚染処理にて、汚染地下水流の本流中に広域流体路層１を設置し、流下する汚染地下水を含めた処理を実施する場合は、図９に示すように、上流部と下流部の遮水壁３０の上端縁の高さを、自然地下水流の水位より低く設置し、上流部より系内に地下水が入り込み、そして下流部より系外に地下水が排出されるような設定とする。またこの際、系内で増殖した細菌や汚染二次代謝物の処理系外ヘの流出を最小限とするための調整処理部５２を系内に設置する。
【０１６０】
図９に示す方法はその一例として、広域流体路層１を遮水壁３０で囲み、その囲みの中の広域流体路層１中の飽和部下側に散気管５３を設置し、この散気管５３により前記調整処理部５２に充分に空気を供給することで原生動物の生育や二次代謝物の微生物分解を促し、原生動物による細菌の捕食によって細菌数を積極的に減少させた後に、系外へ処理後の地下水を排出する方法を示したものである。
【０１６１】
ところで、図９に示す地下水循環系は、単に地下水流を複雑にするだけのものではなく、広域流体路層１たる人工地層を、遮水壁３０や難透過性壁３１，３２等による難透水ないし遮水施工で仕切ることにより、複数の反応部を形成し汚染対策を実施するに至っている。ここで反応部は、地下で前記難透水ないし遮水施工により区画されているが、互いに連通可能に形成されている。これらの各反応部に一連の流体流を通過せしめることにより、各反応部が連結して成る汚染処理系が構築される。また、単に一部に流体透過性を有する函様構造物等を設置することも、前述した仕切ることの代用となる。函様構造物とすれば、より複雑な流路の設定や水処理用担体／装置等を地下流体系に容易に組み入れることが可能となる。
【０１６２】
かかる汚染処理系は、これまで地上で実施していた反応槽やタンクや配管等で結ばれた従来の水処理プラントの機能を、地下にて補完するものであり、これまで地層を単に汚染対策対象として捉えていた従来技術の発想から飛躍した新たな発想に基づくものである。これは前述した特定の汚染物質に対する汚染対策に用いることに限定されず、他の多くの汚染処理または地下水処理への適用が可能な新しい地下水処理の概念を示すものである。
【０１６３】
なお、このような概念の下、土壌汚染対策方法とシステムとして、自然地層他、広域流体路層１を、遮水壁３０や難透過性壁３１，３２等で仕切ることにより、複数の反応部を形成し井戸様構造体１０を用いて広域流体路層１を通じた地下水の注入と回収による汚染処理系を形成して汚染対策を図る対策方法、または広域流体路層１を通じた気体の回収を行い汚染対策を図る対策方法であれば、これまでの種々掲げた前記実施の形態に係る事例に限定されるものではない。
【０１６４】
例えば、前記広域流体路層１の下方の飽和帯２が地層区分で３層の帯水層を有するものであれば、前述したストレーナ部１１を井戸様構造体１０に軸方向に４つ設けて、広域流体路層１や補助構造物５を通じた循環系を形成する場合もあれば、２つのストレーナ部１１を有する井戸様構造体１０を３本設置し汚染処理系を形成するようにしても良い。
【０１６５】
また、上部から下部の水流を有する循環系と、その反対の水流を持つ循環系を近接させ、広域流体路層１を含めた同一地層中で注入と揚水を組みとして実施し、広域の循環系を形成しても良い。更に難透過性壁３１や難透過性壁３２等による難透水施工の仕切りを多数設けて、より複雑で多機能を有する土壌汚染対策方法とシステムを構築しても良い。また同様の観点にて、複数の広域流体路層１等を互いに離隔して設置し、各広域流体路層１等ごとに構築した各システム同士を更に互いに連通させることによっても、前記土壌汚染対策方法とシステムの構築を図ることができる。
【０１６６】
これまで、汚染物質のうち、特に汚染拡散性が見られる汚染群として３つに大別し、各汚染群毎に広域流体路層１を用いた汚染対策における各種実施の形態を説明してきたが、実際の土壌汚染では、これらの汚染群が組み合わさった複合汚染様を呈する場合も少なくない。かかる場合には、具体的な汚染の態様に応じて前述した各種方法を組み合わせた応用的な運転実施によって対処すれば良い。また、汚染物質は同一でも、汚染濃度、汚染部位に応じて対策方法を適切に選択することで、汚染処理の効率化を図ることができる。
【０１６７】
原位置汚染修復方法の多くは、土壌間隙を縫った流体移動やそれを応用した物質混合を行うことで汚染処理を促すことを基本とする。従来技術では注入、揚水等の流体移動は、点または線に例えられる井戸を用いた流体移動法にて極めて局所的な影響範囲内で実施され、おのずと井戸を用いた流体移動もその流体が限定されることにより対処可能な汚染も限定されるものであった。
【０１６８】
そのため、複合汚染が認められるケースや地層中の様々な汚染形態、例えば、重非水性汚染物質のように、地下空気、地下水、土壌、重非水性汚染溜と多岐の汚染形態にて汚染が認知されるケースでは、それぞれの汚染部位や形態毎に井戸群を配置する等それぞれに個別の対処が必要であった。
【０１６９】
本発明の広域流体路層１を用いた流体制御では、該広域流体路層１の上下面が水平的な拡がりを持って広域に設置させることにより、広範囲な影響範囲にて修復が可能なこと、更に、気体と液体の両流体の移動を同時に実施可能であることを特徴とし、従来技術の有する問題点を克服している。
【０１７０】
併せて、広域流体路層１を用いた流体制御による汚染対策方法について詳細な検討を実施した結果、汚染形態に応じた修復はもとより、複合汚染に対しても、広域流体路層１を用いた一元的な流体移動を基本とした流体制御により、汚染修復を可能とする各種の新規な土壌汚染対策方法とそのシステムを発明するに至った。
【０１７１】
しかしながら、汚染対象地の温度条件や土壌の性質によっては、汚染物質の揮発性や水への移行性が十分でなく、本発明をそのまま全ての汚染物質に適用するのが困難な状況も想定される。例えば、ＰＣＢ、ダイオキシン類等の有機塩素化合物、一部の重金属類や農薬類等が挙げられ、これらの汚染物質は汚染浸入部付近の表土に留まり、浸透や地下水による移動性は少ないとされる。これらの汚染物質との複合汚染ケースでは、これらに対する別途の汚染対策方法と本発明とを組み合わせた応用的な運転により対処することが望ましい。
【０１７２】
また本発明を、汚染された土地にのみに適用するばかりでなく、今後汚染が起こり得る可能性がある土地に対しても、汚染拡散の予防的見地からその適用が望まれる。例えば、農地等の耕作地で窒素含有肥料を用いた場合、余剰の窒素分が地下に浸透し硝酸態窒素汚染として、地下水汚染を誘発する可能性が指摘されている。
【０１７３】
このような場合には、耕作地を造成する際、または農閑期等に本発明たる広域流体路層１と井戸様構造体１０や付帯設備を事前に設置し、以後汚染流出が発覚した際には汚染に応じた前述した処置をとる。これは耕作地に限らず、ガソリンスタンド等、汚染物質やその前駆体を含む物質を取り扱う敷地または予定地等を対象とする。
【０１７４】
本設置により、以後仮に汚染が生じたとしても、本発明の土壌汚染対策方法とそのシステムにより、周囲への汚染拡散被害を最小限に留めることが可能である。また本格的な汚染修復が必要となった場合でも、地上の事業設備はそのままで、事前に設置した広域流体路層１と井戸様構造体１０や付帯設備を用いて、前記汚染に応じた原位置修復を実施すれば良く、操業を妨げることなく汚染リスクの低減を図ることができる。今後汚染が起こり得る可能性がある土地への本発明の適用によって、汚染拡散予防と汚染事業者の汚染対策に係る負担軽減を図ることができる。
【０１７５】
また、前述したように、主に汚染原因地または今後原因地となり得る場所での実施に限らず、主に被汚染地または今後被汚染地となり得る可能性がある場所においては、より簡便な方策にて汚染被害を最少とすることができる。すなわち、広域流体路層１とこれの付帯する補助構造物５等により、地下水流動によって拡散する汚染に対し、その流下の土地にて被る汚染被害を阻止する手段としての適用が可能である。
【０１７６】
図１０および図１１は本発明の第８実施の形態を示している。
図１０は縦断面を、図１１は横断面を示している。本実施の形態では、遮水壁３０で周囲を囲んだ地域の地下に、広域流体路層１と凸様の補助構造物５にて遮水壁の内側と一部または全面が接するような易透水部を設置する。図示した例では、凸様の補助構造物５は、広域流体路層１の上面部の全周に亘り上方に延出しており、前記易透水部は杯状の形態を成す。
【０１７７】
また、遮水壁３０の外側周囲にて自然地下水位が最も高い地点にある遮水壁３０の一部を、外側と連通可能な開放壁３４として開放することで、杯状に形成された易透水部の地下水位Ｗ２を、遮水壁３０の外側周囲の自然地下水位Ｗ１の最高位と同位、またはそれ以上の高位に保つように設置する。このような遮水壁３０の内外の水位差によって、該遮水壁３０の外側周囲に存する汚染物質の内部への滲入を防ぐことが可能となる。また、前記開放壁３４を設ける代わりに、遮水壁３０の内側に非汚染水や洗浄水等の液体を別途注入することにより、前述した遮水壁３０の内外での水位差を保つように設定しても良い。
【０１７８】
広域流体路層１および補助構造物５の設置による遮水壁３０内側での地下水流動を良好に保つ機能は、降雨浸透等による外部の自然水位の急激な変化にも即応し、常に遮水壁３０内側を開放壁３４と同等の水位に保つことに大きく寄与する。また、この杯状の易透水部は、補助構造物５が部分的に閉塞した場合でも、広域流体路層１がバイパスの役目を果たし、遮水壁３０内面部の隅々にわたる地下水の導通を保障し、遮水壁３０内側の地下水位を安定的に所定に保つことを可能とする。
【０１７９】
一般には、汚染の拡散や滲入の主たる媒体は地下水であり、遮水工を施し拡散や滲入を防ぐ手段が採られている。しかしながら、技術的完成度、設置環境、時間経過を経た遮水構造物の老朽化等が相まって、完全な遮水は技術的に困難な場合も多く、時間経過に伴って遮水工内外の物質移動が起こり得る可能性も示唆される。
【０１８０】
本発明に係る広域流体路層１とそれに繋がる凸様の補助構造物５を利用した地下水位の制御による汚染拡散防止方法は、現状の汚染対策に用いられる簡易遮水工技術による拡散防止を補完し、簡便かつより精密な汚染拡散防止方法を市場に提供するものである。
【０１８１】
前記第８実施の形態において、凸様の補助構造物５内に満たされる地下水は、自然地下水位が高い地点にある部分的に開放した開放壁３４を通じてもたらされるものであるが、この開放壁３４を通じて内部に導通する地下水が汚染されている場合や今後汚染が流下してくる可能性がある場合は、非汚染水を別途で補助構造物５に注入するか、この汚染地下水が開放壁３４を通過する前後で適切な汚染処理を施す等の補助操作が必要である。後者について詳細な検討を行った結果、汚染対策方法としては、汚染吸着または分解を促進する粒状物を利用し、通過に伴って汚染処理する方法を組み合わせることにより、補助構造物５内を適切な水質を保てることを確認した。
【０１８２】
図１０および図１１では、一例として粒状汚染処理物質含有部３５を設けたものを示している。ここで粒状汚染処理物質としては、還元鉄粉等が挙げられる。還元鉄粉は、時間を有するがトリクロロエチレン等の有機塩素化合物の脱塩素化を図る弱い処理能を有することが知られており、遮水壁３０内外で地下水の出入量が些少である本方法においては、有機塩素化合物汚染水に対し有効な処理が図れる方法である。
【０１８３】
図中では、前記開放壁３４に沿って部位にて局所的に粒状汚染処理物質含有部３５を設置しているが、その設置場所については、図示した例に限定されるものではない。少なくとも前記開放壁３４の周辺に設置されているのであれば、補助構造物５並びに広域流体路層１中に部分的、または全面に設置しても良く、特に限定されるものではない。また、還元鉄粉を例として挙げたが、使用はこれに限定されるものではなく、汚染状況に応じて、適切な粒状汚染対策物質を選定する。
【０１８４】
本発明に係る土壌汚染対策方法とそのシステムに関して、汚染が見られる土地への適用は、汚染対策対象地が汚染原因地、被汚染地であることを問わない。工業地域でしばしば見られるように、汚染原因地であり、かつ被汚染地でもあるケースにも適用できる。このような場合は、汚染対策対象地の汚染処理と外部よりの汚染拡散による再汚染を防ぐ両目的に対し、本発明を一連として適用することが望ましい。図１０では、広域流体路層１が自然地下水位より下方に存在するが、これは遮水壁３０内部の水位を広域流体路層１部分まで下げ汚染修復を行った後に前記汚染被害を阻止する手段を採った、前記操作を一連で実施した状況を示す一例である。
【０１８５】
また本発明は、広域流体路層１とこれを通じての流体制御によって、前述した各種実施の形態に係る一連の汚染対策を可能とするものであるが、その対策に係る運転および施工管理、それに意志決定には、汚染物質分析や環境分析による現況把握は欠かせない要素である。これらの分析を通じて、汚染程度や環境状況に応じた汚染対策を実施する。
【０１８６】
なお、これまでに説明した各種実施の形態に係る図や事例は、代表的な施工や運転の概略を表現したものであり、本発明に係る土壌汚染対策方法、および土壌汚染対策システムは、表現上でのこれらに限定されるものではない。また、遮水工やアスファルト施工等を実施する等、前述した流体の動態制御を効率良く実施するための補助施工を伴うことは言うまでもなく、各汚染対策地の状況に応じて実施されるべきものであり、前述した各種実施の形態は、これらの付帯施工の有無によって限定されるものではない。
【０１８７】
【実施例】
以下、図１２〜図２５に基づき、前述した各種の実施の形態に係る土壌汚染対策方法および土壌汚染対策システムの実施による汚染対策効果を、実験的に確認するための浄化試験装置とこれを用いた実験結果について説明する。
【０１８８】
図１２は、中規模の浄化試験装置を概略的に示す正面図である。
本装置の本体槽１００は、幅２１０ｃｍ、高さ１００ｃｍ、奥行２０ｃｍ程度の大きさであり、中央の仕切り１０１を挟んで、左右対称の２槽から成り、その内部には仕切り１０１に沿った壁面の上下には井戸様構造物１１０Ａ，１１０Ｂ、対する側壁面には水位調整筒２００が設けられている。
【０１８９】
また、本体槽１００内にて上部井戸様構造物１１０Ａのストレーナ部１１１が位置する高さ部位には、粒径４〜２０ｍｍの砕石を充填して前記広域流体路層１を模した砕石層１０２を配し、その上面部にはステンレスメッシュを介して細砂を、そして下面部には中砂を充填した。
【０１９０】
本体槽１００における流体の流出入は、上部井戸様構造物１１０Ａ内に挿通した配管に通じる付帯装置群２０１〜２０６、本体槽１００内の上部の気相部の配管に通じる付帯設備群２１１，２１２、下部井戸様構造物１１０Ｂ内に挿通した配管に通じる付帯設備群２２１，２２２によって実施した。なお、付帯設備群２０１〜２０６，２１１，２１２，２２１，２２２は、試験の具体的な内容に応じてその構成を変えた。
【０１９１】
また、前記配管途中または本体槽背面に設けたサンプリングポート３００で流体試料を採取し、汚染物質の濃度分析やｐＨ、圧力等の環境分析を実施し、運転管理、効果判定を行った。これらの運転や分析を通じて様々な流体制御と汚染物質処理について詳細な検討を行った結果、土壌汚染対策方法としての新たな技術的知見を得た。以下にその詳細を述べる。
【０１９２】
図１３は、汚染物質を系に加えず流体制御のみを実施し、砕石層１０２の設置効果の検証に用いた浄化試験装置の全体構成を概略的に示す正面図である。本実験では、気体吸引ポンプ２０３を用いて、上部井戸様構造物１１０Ａより気体と液体の回収を行った。回収された液体を、吸引受器２０２にて回収し、適時液体排出ポンプ２０４にて系外に排出した。また回収気体を気体吸引ポンプ２０３より系外に排出した。
【０１９３】
一方、本体槽１００内の気体吸引によって生じた負圧に応じて、吸引される気体をガスリザ−バ２１２より自動供給した。ガスリザ−バ２１２より供給するガスとしては３０％アルゴン含有窒素を用い、減量に応じて適時この混合ガスによる気体供給を行った。また同様に、系への液体供給を水位調整筒２００と水位調整槽２２１を用いて実施した。
【０１９４】
前記浄化試験装置の構成並びに運転条件では、左右の２槽にて同一条件に設定しているが、砕石層１０２の設置効果の検証のため、左槽では砕石層１０２の代わりに細砂１０３を充填し、２槽での設定条件を唯一違えた。かかる条件下にて、一定時間の運転の後に、本体槽１００の背面のサンプリングポート３００から不飽和帯では気体を採取し、サンプル中のアルゴン濃度を測定し、従来技術たる井戸を用いた流体の吸引と、本発明の広域流体路層１たる砕石層１０２を通じた吸引での影響範囲の比較を行い、その設置効果についての検証を行った。
【０１９５】
図１４は前記実験結果として、吸引開始後６時間を経た後（この時点での吸気気体中のアルゴン濃度は２９％）に、前記サンプリングポート３００の各ポイントで採取した気体中のアルゴン濃度を分布図として示している。図中、右槽のアルゴン濃度分布は、ほぼ一様に通気気体中濃度と同様の３０％程度の値を示したのに対し、左槽の分布は、吸気する上部井戸様構造物１１０Ａのストレーナ部１１１付近のみが高い値で、このストレーナ部１１１から離れるにつれて、アルゴン濃度が低下する傾向が見られた。
【０１９６】
本結果から、砕石層１０２を通じた吸気は、従来の吸気井戸を用いた場合よりも、その吸引による影響範囲は広く均一に設定できることが確認された。また６時間を経過した後の吸引水量の比較では、圧倒的に右槽での水量が多く、砕石層１０２を通じた回収や注入といった液体の流体制御が、細砂のそれと比べても容易であることが示唆された。
【０１９７】
続いて、砕石層１０２上部の不飽和帯の気体吸引を伴った揮発性有機汚染物質処理について検討を進めた。ここでは汚染物質としてガソリンを対象として評価を行った。本評価は、当初本浄化試験装置を用いた評価を実施したが、左槽と右槽の汚染初期濃度設定において再現性が得られなかったため、評価系を小規模なカラム試験に変更し評価を実施したものである。
【０１９８】
再現性を得られなかった原因としては、模擬汚染土壌の作成時におけるガソリン成分の揮発が疑われ、この揮発を抑えるために、それぞれ対象土壌にガソリンを混合重量比で１％添加後、間を置かずに液体窒素を用いた凍結粉砕と共に、十分な混合を行ったものを用いてそれぞれの供試模擬汚染土壌を作成した。
【０１９９】
図１５は、カラム試験装置の全体構成を示す概略図である。カラム４００は円筒ガラス製で内径５ｃｍ、長さ５０ｃｍの大きさであり、両端蓋の内部接触部がテフロン（登録商標）またはステンレス製のものを実験に使用した。カラム４００の一方の端をガスリザ−バ２１２に接続し、必要に応じて気体供給を行った。また他方の端には、気体吸引ポンプ２０３と積算ガス流量計２１４を接続し、一定条件にて気体の吸引を行った。
【０２００】
また、カラム４００内に充填した土壌の種類や吸気方法の違いにより、それぞれ（Ａ）、（Ｂ）、（Ｃ）として実験系を区別した。今回用いた供試土壌は３種類であり、（Ａ）と（Ｃ）では細砂４０１と中砂４０２を主とした模擬汚染土壌をそれぞれ別のカラム４００に充填し、（Ｂ）では先の細砂と中砂を更に均一に混合した混合土４０３を２本のカラム４００に充填した。また吸気方法として、（Ａ）と（Ｂ）では吸気の手前で配管を接続し、同一の気体吸引ポンプ２０３で吸気を行ったのに対し、（Ｃ）ではそれぞれのカラム４００に気体吸引ポンプ２０３を別々に接続して吸引を行った。
【０２０１】
前記実験系にて、従来技術たる地層を対象とした汚染吸引手法と地層構造を破壊した後に汚染吸引を行う手法を比較し、それぞれの汚染処理性能について評価を行った。すなわち、実験では（Ａ）、（Ｂ）、（Ｃ）の各実験系での気体吸引速度を同等とし、一定時間の吸気を行った後の残存油分濃度にて処理性能を比較した。
【０２０２】
前記実験の結果、吸引開始後１４日を経た後の（Ａ）、（Ｂ）の各実験系における土壌中の残存油分平均濃度は、それぞれ（Ａ）：０．３５７％、（Ｂ）：０．０１２％であり地層破壊土壌たる（Ｂ）の実験系の処理性能の方が優れていた。ただし（Ａ）の実験系における２つのカラム４００のうち、中砂４０２を充填したカラム４００内の平均濃度は０．００５％であり、（Ｂ）の実験系全体での平均濃度を上回る性能が見られた。一方、細砂４０１を充填したカラム４００内の平均濃度は０．７０９％であった。
【０２０３】
このような結果から、地層破壊によって土壌構成が単純化された方が、成層構造を持つ地層を対象とするよりも、効果的な吸引処理が可能であることが分かった。更にまた、成層構造を持つ地層では、より通気性の高い地層中を吸引ガスが通過する傾向が見られ、処理に斑を生じる場合があることが本実験により示唆された。
【０２０４】
続いて、前記の実験結果を踏まえて（Ｂ）、（Ｃ）の各実験系について処理性能の比較を行った。（Ｃ）の実験系は、（Ａ）の実験系と土壌充填成分は同一だが、吸引方法が異なる。これは、先の実験で（Ａ）の実験系において吸引気体の片流れが起きていたことに対し、それを防ぐ実験条件として、カラム４００の１台に対する吸引流量をそれぞれ等しくなるように設定したことによる。なお、他の基本条件は先の実験と同様とした。
【０２０５】
その結果、吸引開始後１４日を経た後の（Ｂ）、（Ｃ）の各実験系における土壌中の残存油分平均濃度は、それぞれ（Ｂ）：０．００９％、（Ｃ）：０．０１５％であり、両実験系の汚染処理に大差は見られず、両系に良好な処理性能が見られた。本実験により、成層構造を持つ地層に対し、各地層毎に吸引を行う方法と、地層破壊によって土壌構成が単純化されたものを対象とした方法では、ほぼ同等の処理性能を発揮できる可能性が示された。
【０２０６】
図１６は、凸様の補助構造物１０４を併用した吸引法に関する評価を実施した際の中規模の浄化試験装置の概略を示す。左槽の砕石層１０２の上面部を、ステンレスメッシュで覆い、内部に砕石層と同等の粒径４〜２０ｍｍの砕石を充填したステンレスメッシュ製の筒（直径５ｃｍ、高さ１５ｃｍ）を５本均等に配置した。これが凸様の補助構造物１０４に相当するものである。
【０２０７】
また、細砂に灯油を混合重量比で１％添加し、その後十分に撹拌混合したものを供試土壌１０５とし、左槽と右槽のそれぞれに同重量を量り充填した。吸気は、左槽と右槽に繋がるそれぞれの配管を途中でまとめ１台の気体吸引ポンプ２０３にて実施した。一方、吸引される気体をガスリザ−バ２１２より自動供給した。左槽のガスリザ−バ２１２内のガスとしては、３０％アルゴン含有窒素を、右槽のガスリザ−バ２１２内のガスとしては純窒素を、それぞれの減量に応じて適時気体供給を行った。
【０２０８】
前記実験系にて、凸様の補助構造物１０４と砕石層１０２を併用した吸引手法と、砕石層１０２のみの吸引手法を比較し、それぞれの汚染処理性能について評価を行った。すなわち、一定時間の吸気を行った後の吸引気体中のアルゴンガス濃度と、供試土壌中の残存油分濃度にて処理性能を比較した。
【０２０９】
その結果、吸引開始後２３日から２７日までの延べ５日間における吸引気体中の平均アルゴンガス濃度は、２２．６％であった。また２８日後での土壌中の残存油分平均濃度は、それぞれ左槽：０．１２％、右槽：０．５６％であった。本実験により、凸様の補助構造物１０４を砕石層１０２と組み合わせることで、より効果的な吸引処理を図れる可能性が示された。
【０２１０】
また、平均アルゴンガス濃度の結果から、左槽と右槽とで吸引量が異なっていたことが推測された。凸様の補助構造物１０４の実用においては、汚染濃度の高い部分には補助構造物１０４をその濃度に応じて集中させ、逆に汚染が軽微な部分には砕石層１０２のみで吸引を行う等、汚染対策地において、汚染濃度の異なる土壌を対象とする場合に、汚染濃度に応じて吸引量を部分的に調整した運転が有効であることが本実験により示された。
【０２１１】
前記の吸引試験により、吸引量が処理に与える影響が観察されたが、他の要素が吸引処理に与える影響等を別途カラム試験にて詳細に評価した結果、汚染を別途土壌で希釈することにより吸引処理効果を高められることが分かった。
【０２１２】
図１７は、カラム試験装置の全体構成を示す概略図である。本装置の基本構成は、前述した図１５に示すカラム試験装置と同様であり、カラム４００の一方の端をガスリザ−バ２１２に接続し、必要に応じて気体供給を行う一方、他方の端には、気体吸引ポンプ２０３と積算ガス流量計２１４を接続し、一定条件にて気体の吸引を行った。
【０２１３】
カラム４００内に充填する土壌は、細砂に灯油を混合重量比で３％添加した３％灯油添加土壌４０４と、１％添加した１％灯油添加土壌４０５を作成し、それぞれ十分に撹拌混合したものを供試土壌とした。その後、カラム４００内に３号硅砂層に挟まれた２０ｃｍの供試土壌層を作成し、供試カラムとした。各試験系として、（Ａ）３％灯油含有土壌４０４を含むカラム４００を１本のみと、（Ｂ）１％灯油含有土壌４０５を含むカラム４００を３本直列に接続したものに対し、それぞれの系で同等の吸引量を設定し吸気を行った。なお、供気ガスは空気を用いた。
【０２１４】
前記実験系にて、希釈による汚染処理性能について評価を行った。すなわち、一定時間の吸気を行った後の残存油分濃度にて処理性能を比較した。その結果、吸引開始後２０日を経た後の各実験系における土壌中の残存油分平均濃度は、それぞれ（Ａ）：０．８７５％、（Ｂ）：０．５２６％であった。この差の生じた要因としては、付着汚染油分の層厚が希釈により薄くなったこと、吸引圧力の違いによるところ、希釈により分解微生物への毒性が低下したことによる分解促進等が挙げられる。これらの要因におけるそれぞれの寄与程度の確定には至らなかったものの、本希釈操作と吸引の組み合わせによって、より効果的な汚染修復が可能であることが本実験により明らかとなった。
【０２１５】
図１８は、油分の微生物分解処理に凸様の補助構造物１０４と砕石層１０２の適用を検討した際に用いた中規模の浄化試験装置の概略を示す。本装置の基本構成は、前述した図１６に示す装置で用いた左槽と同様であるが、吸気ガスの循環経路に炭酸ガス吸収槽２１５と圧力調整槽２１６を加えたこと、系内の酸素消費分を補うガスリザ−バ２１２内のガスとして酸素を用いたこと、それに左槽の供気配管の途中で肥料添加のために養液タンク２１７と養液ポンプ２１８を加えた点で異なる。これにより左槽では、油分を資化する好気的微生物の増殖を促す実験系を、一方の右槽では、酸素と肥料添加を行わず微生物の増殖を抑えた対照実験系を設定した。
【０２１６】
前記実験系において、凸様の補助構造物１０４と砕石層１０２を併用した吸引手法の油分の微生物分解処理への適用について評価を行った。すなわち、ガスリザ−バ２１２への酸素供給量と、一定期間を経た後の供試土壌中の残存油分濃度を測定し、その適用性を評価した。
【０２１７】
その結果、酸素の供給が停止した吸引開始後１２４日後にて試験をストップし、供試土壌中の残存油分濃度を測定したところ、左槽：０．０１％以下、右槽：０．９３％であった。そして左槽にて１２４日間で消費した酸素量は延べ１６２３Ｌであった。また別途に土壌中の一般細菌数を測定したところ、左槽：３×１０８ＣＦＵ／ｇ土、右槽：２×１０７ＣＦＵ／ｇ土であった。
【０２１８】
これらの結果から、左槽では好気的微生物による油分の資化が図られたと推測され、油分汚染の微生物処理に凸様の補助構造物１０４と砕石層１０２を併用した吸引手法が適用できる可能性が示唆された。これまでの試験では不飽和帯汚染処理についての評価を実施し、砕石層１０２を利用した吸引が不飽和帯汚染処理に有効であることを確認した。次に、この砕石層１０２を利用した飽和帯汚染についての評価を行った。以下に詳細を説明する。
【０２１９】
図１９は、軽非水性汚染溜を砕石層を利用し回収を図る手法の評価に用いた浄化試験装置の概略を示す。本装置を用いて、軽非水性汚染溜を砕石層１０２の上部での吸引によって地層中より引き出した後に、上部井戸様構造体１１０Ａからの揚水によって砕石層１０２の下部を通じて回収する試みである。
【０２２０】
本評価において、気体の吸引は２重管２０３ａを用いて気体吸引ポンプ２０３を通じて行った。また、軽非水性汚染溜と水の回収は気体吸引ポンプ２０３を用いて行った。一方、供気は本装置の上部の気相部と通じた配管２１９にて大気開放とし、水は水位調整筒２００と水位調整槽２２１を用いて、一定水位になるように供給した。
【０２２１】
また、本装置の背面にあるサンプリングポート３０１を通じて、本装置内の流体吸引を行って、その結果により生じたサンプリングポート３０１周辺の負圧状況に応じて、自動的に軽非水性汚染溜たる灯油が供給されるように、灯油を充填したシリンジ３０２とサンプリングポート３０１とを接続した。
【０２２２】
これらを基本仕様とし、左槽には砕石層１０２と細砂層１０３とを、ステンレスメッシュを介して中部と上部に充填し、右槽の中部と上部には細砂層１０３のみを充填した。吸気は両槽で同一条件で実施し、揚水は上部井戸様構造体１１０Ａのストレーナ部１１１により左右とも同一位置で行い、回収に応じた揚水を実施する設定とした。
【０２２３】
このような本装置を用いて、総液体回収量と軽非水性汚染溜回収量を測定し、従来技術たる右槽と、砕石層１０２を用いた方法たる左槽での軽非水性汚染溜回収について比較評価を実施した。
流体回収が安定した２日目以降、５日間の平均値で評価を行った。左槽の総液体回収量は６３．４ Ｌ／日、軽非水性汚染溜回収量は５２３ ｍｌ／日であったのに対し、右槽の総液体回収量は１２．５Ｌ／日、軽非水性汚染溜回収量は５２ｍｌ／日であった。
【０２２４】
前述した結果から、総液体回収量と軽非水性汚染溜回収量の比は、左槽が１：０．００８、右槽が１：０．００４であり、砕石層１０２を用いた方法が従来技術の約２倍近い効率にて回収できることが分かった。また単純回収量比では、従来技術の約１０倍の回収量が得られた。これらから、単に地下水回収効率を高めた結果が軽非水性汚染溜回収量を上げたのみならず、他の要因、すなわち砕石層１０２の上面部からの気体吸引が軽非水性汚染溜を砕石層１０２に滲出させ回収に寄与していたことが示唆された。
【０２２５】
本件に関し、実験７日目以降は、液体回収を１日１回のみとし実験を継続したところ、軽非水性汚染溜回収量は平均４３８ｍｌ／日で推移し、気体吸引による滲出や揮発等の効果の寄与が極めて高いものであることが示された。
総じて、気体吸引と液体吸引を同時に実施する砕石層１０２を通じた軽非水性汚染溜回収処理は、従来技術に比して効率の高い回収を図れることが明らかとなった。
【０２２６】
続いて、水に溶解した軽非水性汚染物質の砕石層を用いた酸化雰囲気下での原位置処理について評価を実施した。図２０は本評価に用いた浄化試験装置の概略を示す。本装置を用いて、軽非水性汚染物質を含む汚染水を砕石層１０２と、上下の井戸様構造体１１０Ａ，１１０Ｂを用いて地下にて循環し、揚水することなく汚染修復を図る試みである。
【０２２７】
なお、今回の実験では装置設定の都合上、これら汚染水を一旦系外に出してから再注入を行う方法にて代用しているが、実際の運用において、上下の井戸様構造物１１０Ａ，１１０Ｂを結ぶ配管と、上部井戸様構造物１１０Ａ内に設置した水中ポンプ等によって汚染水の系外移動を起こさない循環系を想定した実験系を構築した。
【０２２８】
本評価において、汚染水は、上部井戸様構造物１１０Ａより循環ポンプ２３１にて回収され、以後配管を通じて下部井戸様構造物１１０Ｂから系内に戻され、これの繰り返しによって循環系を構築した。また、下部井戸様構造物１１０Ｂと循環ポンプ２３１を結ぶ配管途中で配管を２箇所分岐し、その上流部には、養液タンク２１７と養液ポンプ２１８に通じた養液供給用の配管を接続し、下流部には、循環水を一定量系外に排出するための定流量排出装置２２３を設置した。
【０２２９】
この定流量排出装置２２３からの排出量に見合った汚染水の補給のために、水位調整筒２００と水位調整槽２２１を用いた汚染水の供給を実施した。ここで汚染水は、ペンタンを強制撹拌によって水に溶解させたものを用いた。また循環に用いた配管の途中で、テフロン袋チューブ２２４を介した循環水中への酸素供給を行った。これらの装置構成を基本とし、左槽中段には砕石層１０２を、右槽中段には自然地層を模した細砂層１０３を設置して実験を行った。なお、左槽中段の砕石層１０２を設置する際、その底面の一部に不透水部を設置した。
【０２３０】
このような本装置を用いて、処理安定時の汚染除去性能について従来技術たる右槽と、砕石層１０２を用いた方法たる左槽での比較評価を実施した。その結果、左槽と右槽とで共に安定した流体運転が不可能であった。すなわち、運転開始後１０日を経て注入が次第に困難な状況となり、以後左槽は１６日目で、右槽は１９日目で注入が不可能となり、それぞれ実験を中止した。
【０２３１】
本現象について原因を調査した結果、増殖した微生物による注入面の閉塞によるものと思われる結論を得た。すなわち注入面の中砂層を微生物密集物が通過することができず、注入面が閉塞したことによる。本結果を踏まえて、微生物の増殖を図る部位を砕石層１０２として閉塞による運転障害の回避を図り、改めて実験を行うこととした。
【０２３２】
前記実験にて微生物増殖を促す操作として、酸素供給と養液供給を行ったが、この供給系を砕石層１０２に移設し閉塞が起こりにくい設定として実験を行った。図２１にその概略を示す。吸気は気体吸引ポンプ２０３を用いて行い、その一部を再度砕石層１０２の下部に設置した通気管２０３ｂを通じて散気することにより、気体の循環系を構築した。
【０２３３】
また、循環されない排出量に見合った気体補給のために、本体槽１００の上部の気相部と通じた通気管２１９を大気開放とし、気体の供給を補った。また、通気管２０３ｂを通じて微生物分解を促すために、養液タンク２１７から養液ポンプ２１８を通じて養液の供給を行った。
【０２３４】
また、別の閉塞への対処として、前記実験系の下部井戸様構造物１１０Ｂと液体排出ポンプ２２５を結ぶ配管途中に、ポア径０．０１ｍｍのラインフィルタ２２６を組み入れた。また、同配管を分岐させ液体排出ポンプ２２５を設置し、一定時間毎に液送方向を逆転した逆洗を実施した。加えて、通気管２０３ｂよりオゾンガスを一定時間毎に散気ガスへ添加し、余剰微生物の殺菌と分解を図る微生物量の制御を併せて実施した。
【０２３５】
その結果、前述した実験では、実験開始後２０日以内で井戸閉塞が見られたが、本実験では１０６日を経ても閉塞による運転障害は観察されなかった。汚染物質の処理に関しても処理が安定した後は、模擬汚染水中油分濃度としておよそ９０ｍｇ／Ｌで供給されていた汚染水が、排出水中では不検出までの分解が図られていた。本評価により、汚染物質を分解する好気微生物の増殖制御を砕石層１０２にて実施することで、水に溶解した軽非水性汚染物質の原位置での効率的処理が可能であることが明らかとなった。
【０２３６】
また、前述した洗浄試験装置を用いて、他の汚染物質に対する本法の適用性を検討したところ、他の石油系炭化水素類に関しても、同様な運転にて処理が可能であった。一方、重非水性汚染物質たる有機塩素化合物類に関しては、微生物分解を図るよりも、循環気体への移相を図り、地上部にて処理する方法が適することが分かった。また、硝酸態窒素類に関してはオゾン添加は却って逆効果であり、他の逆洗やフィルタ処理のみで閉塞対処を実施することで良好な処理が可能であることを併せて確認した。
【０２３７】
続いて、飽和帯基底部に存する重非水性汚染溜の砕石層を用いた原位置処理について評価を実施した。重非水性汚染溜処理においては、飽和帯の地下水を揚水し、地層間隙を大気と置換した後に砕石層と凸様補助構造物を用いた加熱吸引処理方法について評価を実施した。
【０２３８】
図２２は、加熱吸引処理評価に用いた洗浄試験装置の概略図である。吸引は、気体吸引ポンプ２０３にて上部井戸様構造体１１０Ａを通じて、砕石層１０２と凸様の補助構造物１０４を介して行った。また加熱源として、過酸化水素水と土壌との反応熱を利用するために、薬液注入ポンプ２４１と薬液ボトル２４２から加熱配管２４３を経て、下部井戸様構造体１１０Ｂを通じて模擬飽和帯基底部へ熱した過酸化水素水を注入した。
【０２３９】
模擬飽和帯基底部はシルト土壌を充填し、その上面に約５ｃｍ間隔で窪み（直径３ｃｍ、深さ３ｃｍ）を作成し、この窪みに重非水性汚染溜が溜まる部分を作成した。その上部には中砂層、砕石層、細砂層と充填し試験に供した。なお、試験開始直前に、模擬飽和帯基底部直上の本体槽１００の背面部にあるサンプリングポート３００からトリクロロエチレン原液９９を５０ｍｌ注入し、模擬飽和帯基底部上面に重非水性汚染溜を形成させた。過酸化水素水の再添加は、反応部の温度が注入過酸化水素水温度に戻った時点で数回に分けて実施した。
【０２４０】
その結果、注入過酸化水素水の温度を約７０度で実施した場合、添加後の飽和帯基底部における最高温度は９３度となった。以後７０度に低下するまで約５時間を要した。この反応を５回繰り返して処理を終了し、系内に残存する液体とシルト土壌中と中砂中に含まれるトリクロロエチレン濃度を測定して残存総量を求めた結果、０．３５ｇの残存が確認された。初期投入量５０ｍｌは約７３ｇに相当し、その結果、本処理によって９９．５％以上のトリクロロエチレンによる重非水性汚染溜が処理されたことを確認した。
【０２４１】
前述した例では過酸化水素を用いたが、他の過酸化物として過マンガン酸、過硫酸等の過無機酸や、過酢酸等の過有機酸を含む加熱溶液の利用について検討を行ったが、過酸化水素に比して汚染物質の気化作用は小さく、有効な処理が図れなかった。追加の検討にて、これらは汚染物質の直接分解が主たる処理になる他、残成分による土壌閉塞、反応後の残成分の回収や洗浄等を必要とする等、操作は過酸化水素の場合と比べ操作が煩雑になり、適用に難があることを確認した。
【０２４２】
総じて、温過酸化水素水を用いた加熱吸引処理は、重非水性汚染溜処理に有効であることが示された。また、実用時に注入される温過酸化水素水は、注入点を中心に同心円的に拡がると考えられ、処理部位もそれに伴って擬似円面のように拡大することが予想される。この処理によって生じた気化トリクロロエチレンを回収するためには、広域を対象とできる砕石層１０２と凸様の補助構造物１０４を介した気体吸引との併用が望ましいものであることが示唆された。
【０２４３】
続いて、砕石層１０２を用いた還元雰囲気下での地下水循環を用いた原位置処理について評価を実施した。砕石層１０２の設置面は飽和帯と不飽和帯を跨いで設置するために、上部空隙には分子状酸素が存在し、還元雰囲気を設定して地下水循環を実施する場合の障害となる。この障害を克服するために、地下水面下の砕石層１０２の一部に還元鉄を含む層を設置することで、循環水中の還元雰囲気を保持する方法について検討を行った。更にこの条件下での汚染物質分解についての引き続き検討を行った。
【０２４４】
図２３は、還元雰囲気下での地下水循環評価を実施した浄化洗浄装置の概略図である。今回の実験では、砕石層１０２を２分するように粘土層１０６を設置し、砕石層１０２の上層を、地下水の還元化と微生物の増殖を図る活性化反応層とし、また砕石層１０２の下層を、帯水層よりの汚染地下水と前述した活性化を図った地下水を混合し汚染処理を図る混合処理層とした。
【０２４５】
更に本体槽１００内に粘土にて屈曲路１０７を設置し、両地下水の混合を促した。そしてこの各層を連結するように地下水循環系を構築した。すなわち、上下に３つのストレーナ部を有した井戸様構造物１２０をそれぞれの層に設置し、中央のストレーナ部１２１ｃから地下水を循環ポンプ１２２にて回収し、上下のストレーナ部１２１ａ，１２１ｂより再び系内に通水する循環系を構築した。
【０２４６】
このような還元反応部１０８は左槽に設置し、一方、右槽には還元鉄粉を用いず砕石のみを充填して本実験の対照とした。土壌充填後、両槽には一度沸騰させ静置で放冷した脱気水を満たした後に循環を開始し、１日毎に循環水中の溶存酸素濃度を測定し両者の比較によって評価した。
【０２４７】
その結果、循環当初の溶存酸素濃度は何れも０．０１ｍｇ／Ｌ以下であったが、１日を経た時点で右槽の溶存酸素濃度は１．５３ｍｇ／Ｌに上昇し、以後日数経過に従った上昇が観察され、６日を経過した時点で５．８６ｍｇ／Ｌに達した。一方、左層の循環水中の溶存酸素濃度は０．０１ｍｇ／Ｌ以下で常に安定していた。
【０２４８】
６日を経過した時点で、左層の循環水の酸化還元電位を測定したところ、−２５６ｍＶの還元雰囲気下にあることが確認された。本実験により地下水面下の砕石層１０２の一部に還元鉄を含む層を設置することで、砕石層１０２を用いた地下水循環系において還元雰囲気を保持できることが分かった。
【０２４９】
続いて、汚染水の処理試験を実施した。図２４にその概要を示す。本装置では、活性化反応層中での微生物の増殖を図るために、循環ポンプ２３１を繋ぐ配管の途中に、養液タンク２１７と養液ポンプ２１８に通じた養液供給用の配管を接続してエタノールを系内に供給した。また、この微生物の増殖に伴う井戸閉塞への対処として、同様に循環ポンプ２３１に繋ぐ配管の途中に、ポア径０．０１ｍｍのラインフィルタ２２６を組み入れた。
【０２５０】
また、ラインフィルタ２２６の濾過面に通じた配管と、液体排出ポンプ２２５を設置し、閉塞に応じて濾過残さを回収し、濾過面の洗浄を実施した。汚染の分解処理は、汚染物質としてテトラクロロエチレン１ｍｇ／Ｌ、硝酸イオン１００ｍｇ／Ｌ、ベンゼン０．１ｍｇ／Ｌを脱気水に混合して複合汚染水を作成し、本体槽１００の下部より静かに注入して砕石層１０２の上部まで注水し実験に供した。
【０２５１】
その結果、開始後２週間までは顕著な分解が見られなかったが、それ以降は分解が進み、開始後５週間経過の時点で、循環水中の各汚染物質濃度はそれぞれ環境基準値以下または検出限界以下となった。なお、この期間中、増殖した微生物による閉塞は見られず、ラインフィルタ２２６の洗浄も実施することはなかった。本試験により、多くの汚染に対し本系にて分解が図れることがわかった。
【０２５２】
引き続き、この系の仕様を一部変更し、汚染地下水の連続処理について評価を実施した。図２５にその概要を示す。すなわち、循環ポンプ２３１を繋ぐ配管の途中に、循環水を一定量系外に排出するための定流量排出装置２２３を設置すると共に、この排出に見合った汚染水の補給のために、水位調整筒２００と水位調整槽２２１を用いた汚染水の供給を実施した。汚染水は、前述した実験で用いた複合汚染水をそのまま本実験にも供した。また、排出水中の嫌気細菌量を減少させてから放流とするための好気的曝気槽２５０を設置し、原生動物等による細菌の捕食を促す処理を行った。
【０２５３】
その結果、開始直後から循環水の汚染濃度の低下が見られ、５週間を経過して以後、各汚染濃度はそれぞれテトラクロロエチレン０．００５ｍｇ／Ｌ以下、硝酸イオン１ｍｇ／Ｌ以下、ベンゼン０．００７ｍｇ／Ｌ付近で安定し、いずれも環境基準を満たすことができた。また、この時点での排出水中の全細菌数は６×１０７ＣＦＵ／ｍｌであったが、好気的曝気槽を通じた後は３×１０４ＣＦＵ／ｍｌとなり細菌数で３オーダーの減少が見られた。また、４週間目より閉塞によって２つの循環ポンプ２３１の負荷が高くなったため、１日に１回この循環を逆転し循環水をラインフィルタに通過させ逆洗を行ったところ、以後安定した運転が可能となった。
【０２５４】
前記実験により、砕石層１０２を用いた還元雰囲気下での地下水循環原位置処理が、各種汚染物質に対し有効であり、環境基準を満たす地下水処理が可能であることが本実験により示された。
【０２５５】
以上の実施例で説明したように、本発明に係る土壌汚染対策方法および土壌汚染対策システムに関しては、その流体制御の対象となる処理系における流体の汚染物質分析や環境分析等を実施し、汚染程度や環境状況に応じた汚染対策を実施することも重要となる。
【０２５６】
【発明の効果】
本発明に係る土壌汚染対策方法および土壌汚染対策システムによれば、地下の飽和帯と不飽和帯の境界部周辺に沿って設置する広域流体路層を通じることで、流体の注入およびまたは流体の回収による流体制御を、地下のより広い範囲で多数の井戸を設けることなく実施可能となり、多大なコストアップを招くことなく、広い範囲の土壌および地下水から効率良く汚染物質を除去することが可能となる。
【０２５７】
しかも、前記広域流体路層を通じた流体制御によって、広域流体路層以深に存する汚染物質が広域流体路層以浅の土壌へ拡散することを防止することができ、また逆に、広域流体路層以浅に存する汚染物質が広域流体路層以深の土壌へ拡散することも防止することができる。加えて、前記広域流体路層を通じて多様な流体流の操作により、前述した汚染拡散の防止を更に強化することが可能となる。
【図面の簡単な説明】
【図１】本発明の第１実施の形態に係る土壌汚染対策方法を実施するための土壌汚染対策システムを概略的に示す縦断面図である。
【図２】本発明の各種実施の形態に係る広域流体路層を概略的に示す斜視図である。
【図３】本発明の第１実施の形態に係る土壌汚染対策方法を実施するための土壌汚染対策システムにおける流体制御を説明するための縦断面図である。
【図４】本発明の第２実施の形態に係る土壌汚染対策方法および土壌汚染対策システムを概略的に示す縦断面図である。
【図５】本発明の第３実施の形態に係る土壌汚染対策方法および土壌汚染対策システムを概略的に示す縦断面図である。
【図６】本発明の第４実施の形態に係る土壌汚染対策方法および土壌汚染対策システムを概略的に示す縦断面図である。
【図７】本発明の第５実施の形態に係る土壌汚染対策方法および土壌汚染対策システムを概略的に示す縦断面図である。
【図８】本発明の第６実施の形態に係る土壌汚染対策方法および土壌汚染対策システムを概略的に示す縦断面図である。
【図９】本発明の第７実施の形態に係る土壌汚染対策方法および土壌汚染対策システムを概略的に示す縦断面図である。
【図１０】本発明の第８実施の形態に係る土壌汚染対策方法および土壌汚染対策システムを概略的に示す縦断面図である。
【図１１】本発明の第８実施の形態に係る土壌汚染対策方法および土壌汚染対策システムを概略的に示す横断面図である。
【図１２】本発明の第１実施例に係る浄化試験装置を概略的に示す縦断面図である。
【図１３】本発明の第２実施例に係る浄化試験装置を概略的に示す縦断面図である。
【図１４】本発明の第２実施例に係る浄化試験装置による実験結果を概略的に示す説明面図である。
【図１５】本発明の第３実施例に係るカラム試験装置を概略的に示す説明面図である。
【図１６】本発明の第４実施例に係る浄化試験装置を概略的に示す縦断面図である。
【図１７】本発明の第５実施例に係るカラム試験装置を概略的に示す説明図である。
【図１８】本発明の第６実施例に係る浄化試験装置を概略的に示す縦断面図である。
【図１９】本発明の第７実施例に係る浄化試験装置を概略的に示す縦断面図である。
【図２０】本発明の第８実施例に係る浄化試験装置を概略的に示す縦断面図である。
【図２１】本発明の第９実施例に係る浄化試験装置を概略的に示す縦断面図である。
【図２２】本発明の第１０実施例に係る浄化試験装置を概略的に示す縦断面図である。
【図２３】本発明の第１１実施例に係る浄化試験装置を概略的に示す縦断面図である。
【図２４】本発明の第１２実施例に係る浄化試験装置を概略的に示す縦断面図である。
【図２５】本発明の第１３実施例に係る浄化試験装置を概略的に示す縦断面図である。
【符号の説明】
Ａ…流体流
Ｂ…地下水流
Ｃ…地下水流
Ｄ…地下空気流
Ｅ…熱風
Ｆ…熱洗浄液
Ｋ…洗浄用水
Ｎ１…軽非水液溜
Ｎ２…重非水液溜
Ｒ…不透水層
Ｗ…地下水面
１…広域流体路層
２…飽和帯
３…不飽和帯
４…覆土
５…補助構造物
６…自然地層区分
１０…井戸様構造体
１１ａ…ストレーナ部
１１ｂ…ストレーナ部
１１ｃ…ストレーナ部
１２…シーリング
１３…パッカー
１４…吸引管
１５…注入管
１６…散気管
１７…給気管
１８…熱供給管
１９…散水管
２１…真空ポンプ
２２…液体搬出ポンプ
２３…汚染処理装置
２４…流体受槽
３０…遮水壁
３１…難透過性壁
３２…難透過性壁
３２ａ…フランジ部位
３３…還元性物質含有部
３４…開放壁
３５…粒状汚染処理物質含有部
４０…水中ポンプ
４０ａ…集水部
４１…給水管
４２…ストレーナ
４３…濾過物回収管
４４…回収部
５０…養液供給装置
５１…養液供給槽
５２…調整処理部
５３…散気管[0001]
BACKGROUND OF THE INVENTION
The present invention generally belongs to the field of soil contamination countermeasures, and particularly relates to a soil contamination countermeasure method and a soil contamination countermeasure system for removing and repairing contaminants from soil and groundwater.
[0002]
[Prior art]
Today, soil contamination due to harmful substances that cause environmental loads such as trichlorethylene is being recognized as a serious social problem as seen in the enforcement of the Soil Contamination Countermeasures Law. Examples of conventional techniques for countermeasures against such soil contamination include, for example, a vacuum suction method for contaminated strata and contaminated air existing in the underground unsaturated zone, a pumped water aeration method for contaminated groundwater existing in the saturated zone, and a sparging method Is known as a representative measure. These measures are generally techniques for injecting a fluid into the soil and shifting the contamination into the fluid, and then recovering and treating the fluid, and the fluid used depends on the geological situation and the like.
[0003]
The injection and recovery of these fluids are generally performed by a well having a strainer structure or the like, and are performed within an influence range approximated to a concentric circle from the injection and recovery points. Moreover, when this influence range needs to be installed in a wide area, for example, as shown in Patent Documents 1 to 3, generally, a measure of installing a plurality of wells has been taken. In addition, as disclosed in Patent Document 4, a pollution recovery method has been proposed in which a suction well is installed for each contaminated formation, and contaminants are removed by suction in units of contaminated formation.
[0004]
On the other hand, in contrast to the point injection and recovery of the fluid using the well described above, the fluid is injected in a linear region by a predetermined permeation facility, and the fluid including the contaminant is recovered in a point manner. A measure has already been proposed as shown in Patent Document 5. Furthermore, although similar in structure to the infiltration facility shown in Patent Document 5, a granular passage such as a cave with a lid is provided in the soil, and the surrounding pollutant gas is passed through this granular passage. As shown in Patent Document 6, there has already been proposed a method for mainly collecting the above.
[0005]
[Patent Document 1]
JP 2002-11456 A
[Patent Document 2]
JP 2002-301465 A
[Patent Document 3]
Japanese Patent Laid-Open No. 11-169836
[Patent Document 4]
JP-A-5-231086
[Patent Document 5]
Japanese Patent Laid-Open No. 2001-225054
[Patent Document 6]
JP 2002-346539 A
[0006]
[Problems to be solved by the invention]
However, in the techniques shown in Patent Documents 1 to 4 described above, it is assumed that a large number of wells are installed vertically or horizontally in accordance with the spread of the soil contamination range. Due to cost-effective limitations, many of the realities were not always in a situation where an ideal soil restoration was possible using a sufficient number of wells.
[0007]
Moreover, in the technique shown by patent document 5, although the linear screen structure part for inject | pouring a fluid into soil can be installed in the wide area | region of the ground surface, this screen structure part is a function to flow down a liquid below. Was limited to only. Moreover, since the recovery of the fluid in which the contaminant is taken in is limited to a narrow range near the recovery point as in the above-mentioned Patent Documents 1 to 4, a large number of wells are eventually installed to recover in a wide range. There was a need.
[0008]
Furthermore, in the technique disclosed in Patent Document 6, even if the groove-like granular path is continuously provided in the soil, it is eventually included in the fluid only within a limited range along the granular path. There is a problem that the pollutant cannot be collected, and in order to collect it in a wide range, it is necessary to install a large number of granular paths in the form of honeycombs or lattices in the soil.
[0009]
In general, in the techniques shown in Patent Documents 1 to 6, the injection and recovery of fluids are roughly divided into implementation in the underground part using a well or the like and the surface part using an underground groove or the like, and the target fluid is naturally. In addition, the scope of anti-contamination measures was limited. In addition, as the depth of the ground becomes deeper, the burden of installing the injection equipment becomes larger, and it tends to be difficult technically and cost-effectively to set the influence range widely.
[0010]
The present invention has been made paying attention to the above-described problems of the prior art, and is intended to further reduce the cost by simplifying the recovery and injection of various fluids used in soil contamination repair. An object of the present invention is to provide a soil contamination countermeasure method and a soil contamination countermeasure system that can perform injection and recovery in a wider area and are extremely versatile.
[0011]
[Means for Solving the Problems]
The inventors focused on the boundary surface of groundwater, which is the main diffusion medium of soil contamination, and made a wide-area fluid path layer (1) as an artificial stratum in the vicinity of this boundary by diligent investigation on soil contamination countermeasures. Through this wide fluid path layer (1), it was clarified that recovery and injection can be carried out easily and over a wide range regardless of gas or liquid. In view of this conclusion, the gist of the present invention for achieving the above-described object lies in the following items.
[0012]
[1] In a soil pollution countermeasure method for removing and repairing contaminants from soil and groundwater,
A wide-area fluid channel layer (1) including many gaps communicating with each other is installed along the periphery of the boundary between the underground saturated zone (2) and unsaturated zone (3),
According to at least one of injection of fluid to the periphery of the wide area fluid path layer (1) and recovery of fluid from the periphery of the wide area fluid path layer (1) through the wide area fluid path layer (1). A soil contamination countermeasure method characterized by performing fluid control.
[0013]
[2] The soil contamination countermeasure method according to [1], wherein the gas and liquid as the fluid are collected in parallel through the wide-area fluid path layer (1).
[0014]
[3] After the contaminated soil having no stratum structure is laminated on the wide-area fluid path layer (1), the contaminants in the contaminated soil are removed by fluid control through the wide-area fluid path layer (1). The soil contamination countermeasure method according to [1] or [2], wherein
[0015]
[4] After the contaminated soil is laminated on the wide-area fluid path layer (1) by designating areas according to the pollution concentration, the fluid control through the wide-area fluid path layer (1) according to the pollution concentration for each area The soil contamination countermeasure method according to [1] or [2], wherein the contaminant in the contaminated soil is removed by
[0016]
[5] After performing the operation of mixing contaminated soil and averaging the concentration of pollutants, or performing the operation of mixing the guest soil and averaging by lowering the concentration of pollutants, the flow through the wide fluid path layer (1) The soil contamination countermeasure method according to [1] or [2], wherein contaminants in the contaminated soil are removed by fluid control.
[0017]
[6] An impermeable wall (31, 32) is installed in or around the wide-area fluid path layer (1), and the continuity of the soil gap is partially blocked by the impermeable wall (31, 32). The soil contamination countermeasure method according to [1], [2], [3], [4] or [5], wherein the removal of contamination is promoted by correcting the fluid flow path.
[0018]
[7] A groundwater circulation system is formed in the saturation zone (2) by fluid control through the wide-area fluid path layer (1) [1], [2], [3], [4] , [5] or [6] soil contamination countermeasure method.
[0019]
[8] The soil pollution control method according to [1], [2], [3], [4], [5], [6] or [7], wherein the groundwater system is maintained in an oxidizing atmosphere. .
[0020]
[9] [1], [2], [3], [4], [5], [5], wherein water treatment using aerobic metabolism of aerobic microorganisms is also performed in the groundwater system 6], [7] or the soil contamination countermeasure method according to [8].
[0021]
[10] The soil pollution control method according to [1], [2], [3], [4], [5], [6] or [7], wherein the groundwater system is maintained in a reducing atmosphere. .
[0022]
[11] [1], [2], [3], [4], [5], [6] characterized in that water treatment using anaerobic metabolism of anaerobic microorganisms is performed in the groundwater system. ], [7], [8] or [10] soil contamination countermeasure method according to [10].
[0023]
[12] Purifying the groundwater by purifying a part of the groundwater through the contamination treatment device (23) installed on the ground and returning the groundwater treated by the contamination treatment device (23) to the groundwater system again. Soil according to [1], [2], [3], [4], [5], [6], [7], [8], [9], [10] or [11] Pollution control methods.
[0024]
[13] By injecting liquid from the surface and the lower part of the saturation zone (2), and forming a fluid flow for collecting the liquid in the wide-area fluid path layer (1), the saturation zone (2) and the [1], [2], [3], [4], [5], [6], [7], [8], characterized by removing contaminants present in the unsaturated zone (3) The soil contamination countermeasure method according to [9], [10], [11] or [12].
[0025]
[14] Air is diffused from below the groundwater surface, and pollutants are collected together with the air diffused gas by intake through the wide-area fluid channel layer (1) [1], [2], [3] , [4], [5], [6], [7], [8], [9], [10], [11], [12] or [13].
[0026]
[15] [1], [2], [3] characterized by collecting vaporized pollutants by suction through the wide-area fluid path layer (1) together with an operation for promoting vaporization of pollutants in the soil. ], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13] or [14] Countermeasure.
[0027]
[16] The soil contamination countermeasure method according to [15], wherein the operation for promoting the vaporization of the contaminant is injecting a heated peroxide solution into the soil.
[0028]
[17] The wide area fluid path layer (1) includes a plurality of gaps that protrude in a substantially vertical direction from at least one of the upper and lower surface portions and communicate with each other in the same manner as the wide area fluid path layer (1). Forming a convex auxiliary structure (5) communicating with the road layer (1);
Fluid injection into the surroundings of the wide area fluid path layer (1) and the auxiliary structure (5) through the wide area fluid path layer (1) and the auxiliary structure (5), and the wide area fluid path layer (1) [1], [2], [3], [4], [5], [6], [6], [6], [1], [2], [3], [4], [5] 7], [8], [9], [10], [11], [12], [13], [14], [15] or [16].
[0029]
[18] A water-impervious wall (30) surrounding the periphery of the wide-area fluid path layer (1) is installed in the basement, and the auxiliary structure (5) is placed around the upper surface of the wide-area fluid path layer (1). Forming the inner wall of the water-impervious wall (30) in contact with part or the entire surface,
A part of the impermeable wall (30) at a point where the natural groundwater level is the highest around the outer wall of the impermeable wall (30) is opened so as to be able to communicate with the outer side, or a liquid is formed inside the impermeable wall (30). In order to maintain the groundwater level in the auxiliary structure (5) at a level substantially equal to or higher than the highest natural groundwater level around the outside of the impermeable wall (30). The soil contamination countermeasure method according to [17].
[0030]
[19] By partitioning the wide-area fluid path layer (1) by impervious or impervious construction, a plurality of reaction sections are formed that are communicably communicated with each other underground, and a series of fluid flows in each reaction section. [1], [2], [3], [4], [5], [6], characterized in that a contamination treatment system in which the reaction parts are connected to each other is constructed. [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17] or [18] Soil pollution countermeasures.
[0031]
[20] In a soil pollution control system for removing and repairing contaminants from soil and groundwater,
A wide-area fluid path layer (1) installed along the boundary between the underground saturated zone (2) and the unsaturated zone (3) and including a number of gaps communicating with each other;
A well-like structure (10) installed to be able to communicate with the wide-area fluid path layer (1) from the ground,
Injection of fluid into the periphery of the global fluid path layer (1) and recovery of fluid from the periphery of the global fluid path layer (1) through the global fluid path layer (1) by the well-like structure (10) Among them, a soil contamination countermeasure system characterized in that it can perform fluid control by at least one of them.
[0032]
[21] The soil pollution control system according to [20], wherein the wide-area fluid path layer (1) is laminated in a state in which granular materials are densely gathered within a predetermined range.
[0033]
[22] The wide-area fluid path layer (1) includes a plurality of gaps that protrude in a substantially vertical direction from at least one of the upper and lower surfaces of the wide-area fluid path layer (1) and communicate with each other like the wide-area fluid path layer (1). The soil pollution control system according to [20] or [21], wherein a convex auxiliary structure (5) communicating with the road layer (1) is formed.
[0034]
[23] The soil pollution control system according to [22], wherein the auxiliary structure (5) includes a material that promotes adsorption or decomposition of a contaminant.
[0035]
[24] The well-like structure (10) includes a plurality of strainer portions (11) communicating with the ground in the axial direction, and at least one of the strainer portions (11) is formed as the wide-area fluid path layer ( The soil contamination countermeasure system according to [20], [21], [22] or [23], which is disposed at a position communicating with 1).
[0036]
[25] Pump (40) for injecting groundwater collected from one strainer part (11) into the soil from the other strainer part (11) into the well-like structure (10) Provided,
The water collection part of the pump (40) is covered with a strainer (42) for filtering ground water collected from the water collection part,
A position where the air supply path (17) which can be ventilated from the ground is inserted into the well-like structure (10), and the lower end outlet of the air supply path (17) faces the inside of the strainer from the water collecting part side. Placed in
The filtrate collection path (43) communicating to the ground is inserted into the well-like structure (10), and a collection section (44) surrounding the strainer is provided at the lower end of the filtrate collection path (43).
When the filtrate accumulated on the strainer surface with the operation of the pump (40) is separated by aeration from the air supply path (17), the separated filtrate is separated by the filtrate collection path (43). The soil pollution control system according to [24], wherein the soil contamination is collected on the ground together with aeration gas.
[0037]
The present invention operates as follows.
According to the soil contamination countermeasure method described in [1] according to the present invention, when the wide-area fluid path layer (1) is installed along the periphery of the boundary between the underground saturated zone (2) and the unsaturated zone (3). The wide-area fluid path layer (1) spreads in a planar shape with a predetermined layer thickness, and exhibits excellent fluid permeability due to the numerous gaps communicating with each other over the entire area.
[0038]
The wide area fluid path layer (1) includes many gaps that communicate with each other and expand three-dimensionally, and these gaps open to the outside over the entire surface of the wide area fluid path layer (1). Any form may be used as long as it is, but specifically, as described in the above [21], for example, granular materials such as crushed stones and gravel are laminated in a densely gathered state within a predetermined range. It can be installed very easily.
[0039]
Through such a wide fluid path layer (1), it becomes possible to perform fluid control by injecting fluid and / or recovering fluid without providing a large number of wells in a wider underground area. Pollutants can be efficiently removed from a wide range of soils and groundwater without increasing costs.
[0040]
The wide area fluid path layer (1) has a screen function on the entire surface, and the upper surface portion of the wide area fluid path layer (1) can realize a function of recovering gas more efficiently. In the lower surface portion of (1), the function of recovering the exuded groundwater more efficiently can be realized, thereby enabling the recovery of the contaminant as the fluid and the injection of the fluid necessary for the countermeasure against the contamination.
[0041]
In particular, the fluid injection and recovery according to the prior art was performed as if it were a point or a line, whereas the fluid flow layer (1) by the soil contamination countermeasure method according to the present invention is used. The injection and / or recovery is performed in a planar shape, and the efficiency of fluid injection and / or recovery can be significantly increased as compared with the prior art.
[0042]
Moreover, the fluid control through the wide-area fluid path layer (1) can prevent the contaminants existing deeper than the wide-area fluid path layer (1) from diffusing into the soil shallower than the wide-area fluid path layer (1). Conversely, it is also possible to prevent the pollutants existing in the shallower area of the wide fluid path layer (1) from diffusing into the soil deeper than the wide area fluid path layer (1). In addition, it is possible to further enhance the prevention of contamination diffusion described above by manipulating various fluid flows through the wide area fluid path layer (1).
[0043]
In particular, in the general restoration process of the prior art, when the unsaturated zone (3) is preceded and the saturated zone (2) is treated later, groundwater contamination in the saturated zone (2) may occur. The upper unsaturated zone (3) may infiltrate due to capillarity, etc., and may cause recontamination due to contamination diffusion. However, according to the soil pollution control system, the wide-area fluid path layer (1) is By installing so as to partition between 2) and the unsaturated zone (3), recontamination due to capillary action can also be prevented.
[0044]
In addition, as described above, the function of recovering gas more efficiently can be realized at the upper surface of the wide area fluid path layer (1), and the exuded groundwater can be recovered more efficiently at the lower surface of the wide area fluid path layer (1). As described in [2] above, the recovery of gas and liquid as fluids is performed in parallel through the wide-area fluid path layer (1), thereby improving the efficiency of the contamination process. Is possible. In particular, it is possible to perform more rapid contamination treatment by simultaneously performing fluid control mainly for gas in the saturation zone (2) and mainly for liquid in the unsaturated zone (3).
[0045]
In addition, as described in [3] above, by laminating contaminated soil having no geological structure on the wide area fluid path layer (1), fluid control is performed through the wide area fluid path layer (1). By using unified fluid control using the wide-area fluid path layer (1) for contaminated soil that has destroyed the natural strata structure without arranging many wells in the polluted natural strata as in the prior art Contamination treatment is possible.
[0046]
Further, as described in [4] above, after the contaminated soil is designated on the basis of the contamination concentration and laminated on the wide-area fluid path layer (1), the wide-area fluid corresponding to the contamination concentration for each of the areas. By controlling the fluid through the road layer (1), for example, in a region where the concentration of contamination is high, it is possible to efficiently perform the contamination processing with gradual adjustment such as locally increasing the fluid suction. Here, in order to locally increase the fluid suction, for example, the auxiliary structure (5) described in [18] described later may be formed in the area.
[0047]
In addition, as described in [5] above, after performing an operation of mixing contaminated soil and averaging the concentration of pollutants, or an operation of mixing the soil and lowering the concentration of contaminants and averaging, By performing fluid control through the wide-area fluid path layer (1), it is possible to efficiently remove contaminants from highly contaminated soil. This is a method that has been found based on the fact that it is considered that the main factors are the metabolic reaction inhibition of microorganisms and the fact that there are few contact surfaces with gases as the repair rate-determining factors brought about by the high concentration of contamination.
[0048]
In addition, as described in [6] above, a hardly permeable wall (31, 32) is installed inside or around the wide-area fluid path layer (1), and soil is formed by the hardly permeable wall (31, 32). By partially interrupting the continuity of the gap, the fluid flow in the fluid control through the wide-area fluid path layer (1) can be guided in a desired direction, and the airtightness at the time of fluid recovery is particularly enhanced. It is also possible to improve the suction effect. In addition, you may make it install a water-impervious wall (30) instead of a hardly permeable wall (31, 32).
[0049]
In addition, there are various variations in the fluid control through the wide-area fluid path layer (1). For example, as described in [7], the fluid control through the wide-area fluid path layer (1) causes saturation. If the groundwater circulation system is formed in the belt (2), it becomes possible to efficiently recover the pollutants contained in the groundwater circulation system together with the groundwater.
[0050]
Here, as described in [8] above, by maintaining the groundwater system in an oxidizing atmosphere, it becomes possible to further increase the efficiency of the contamination treatment. In order to keep the groundwater system in an oxidizing atmosphere, it is preferable to add molecular oxygen or peroxide to the groundwater system. Specifically, for example, it is optimal to use air or ozone aeration.
[0051]
The groundwater system maintained in an oxidizing atmosphere becomes an environment suitable for the growth of aerobic microorganisms, and as described in [9] above, combined with water treatment using aerobic metabolism of aerobic microorganisms in the groundwater system. By carrying out the process, it is possible to further clean up the contamination more quickly. In addition, by changing the ventilation load such as ozone, the existing amount of microorganisms can be controlled, and after purification, the living organisms can be sterilized. Excellent contamination purification can be performed.
[0052]
On the other hand, contrary to the case described in [8], it is possible to improve the efficiency of the contamination treatment by keeping the groundwater system in a reducing atmosphere as described in [10]. In order to keep the groundwater system in a reducing atmosphere, it is preferable to add reducing substances such as reduced iron powder, sugar and alcohol to the groundwater system.
[0053]
The groundwater system maintained in a reducing atmosphere becomes an environment suitable for the growth of anaerobic microorganisms, and as described in [11] above, combined with water treatment using anaerobic metabolism of anaerobic microorganisms in the groundwater system. By performing this, it is possible to carry out rapid contamination purification as in the case described in [9] above. In addition, even if the surroundings are in an oxidizing atmosphere in the microbial agglomeration, an environment suitable for local growth of anaerobic microorganisms may be established, and combined oxidation / reduction contamination treatment using such a phenomenon. It is also possible to plan simultaneously.
[0054]
In setting the conditions of these oxidation / reduction atmospheres, it is desirable to select an atmosphere similar to the oxidation / reduction state of natural geology as the conditions. On the other hand, if the conditions are changed, it is suggested that precipitates and the like may be generated at the redox boundary surface, causing clogging of the formation and hindering subsequent processing. In implementation, it is possible to carry out pollution purification excellent in operation and management by carefully examining the target pollutant species and natural geological conditions and selecting the conditions each time.
[0055]
Further, as described in [12] above, a part of the groundwater is purified through the pollution treatment device (23) installed on the ground, and the groundwater treated by the contamination treatment device (23) is returned to the groundwater system again. As a result, it is possible to effectively reuse groundwater without wasting it as much as possible, and to sufficiently remove contaminants in the groundwater.
[0056]
In addition, as described in [13] above, liquids such as non-contaminated water or low-concentration contaminated water are injected from the surface and the lower part of the saturation zone (2), and these liquids are injected into the wide-area fluid path layer (1). By forming a fluid flow to be recovered in this manner, contaminants existing in the saturated zone (2) and the unsaturated zone (3) may be removed, or as described in [14] above, Aeration can be performed from below, and the contaminants can be recovered together with the aeration gas by suction through the wide-area fluid path layer (1).
[0057]
When the pollutant is present in the form of a non-aqueous liquid reservoir (NAPL), as described in [15] above, along with the operation for promoting the vaporization of the pollutant in the soil, the wide-area fluid path layer (1 ) To encourage vaporization and collect pollutants.
[0058]
Here, when a pollutant having a specific gravity higher than that of water is present in the base of the saturation zone (2) as a heavy non-aqueous liquid reservoir, and the infiltration of the pollutant from the base to the impermeable layer below it is remarkable As described in the above [16], if the operation of promoting the vaporization of the pollutant is to inject the heated peroxide solution into the soil, the heating containing a peroxide having a heavier specific gravity than water. The solution infiltrates into the impermeable layer, and the heat of reaction accompanying the oxidation of the heated solution can promote vaporization due to volatilization of the heavy non-aqueous liquid reservoir. By suction through the lower surface of the wide-area fluid path layer (1), Volatile contaminants can be reliably recovered.
[0059]
Further, according to the soil contamination countermeasure method described in [17], the wide area fluid path layer (1) protrudes in a substantially vertical direction from at least one of the upper and lower surface portions thereof, and the wide area fluid path layer (1) and Similarly, a convex auxiliary structure (5) including a plurality of gaps communicating with each other and communicating with the wide-area fluid path layer (1) is formed together, and particularly around the auxiliary structure (5). Thus, fluid injection and recovery through the wide fluid path layer (1) can be locally enhanced.
[0060]
In addition, according to the soil contamination countermeasure method described in [18], the impermeable wall (30) surrounding the periphery of the wide-area fluid path layer (1) is installed in the basement, and the auxiliary structure (5) is It forms so that a part or the whole surface may contact the inner wall of the impermeable wall (30) around the upper surface of the wide-area fluid path layer (1).
[0061]
Then, a part of the impermeable wall (30) located at a point having the highest natural groundwater level around the outer side of the impermeable wall (30) is opened so as to be able to communicate with the outer side, or the inner side of the impermeable wall (30) By injecting liquid into the substructure (5), the groundwater level in the auxiliary structure (5) is maintained at a level substantially equal to or higher than the highest natural groundwater level around the outside of the impermeable wall (30). Set. Due to the difference in water level between the inside and outside of the impermeable wall (30), it is possible to prevent infiltration of contaminants existing around the outside of the impermeable wall (30).
[0062]
Furthermore, as described in the above [19], by dividing the wide-area fluid path layer (1) by impervious or impervious construction, a plurality of reaction portions partitioned to communicate with each other underground are formed. It is preferable to construct a contamination treatment system in which the reaction parts are connected by passing a series of fluid flows through the reaction parts.
[0063]
If a plurality of reaction parts are formed in the basement by appropriately selecting or combining the impermeable walls (30) or the hardly permeable walls (31, 32) in this way, each of these reaction parts passes through a series of fluid flows. By performing fluid control, it is possible to construct a contamination treatment system that combines various operations and reaction systems, and it is also possible to quickly carry out contamination purification.
[0064]
The soil contamination countermeasure method according to the present invention as described above can be implemented as simply and efficiently as possible by the soil contamination countermeasure system described in [20]. That is, this soil contamination countermeasure system has the above-mentioned wide-area fluid path layer (1) and the well-like structure (10) installed in this wide-area fluid path layer (1) so that it can communicate from the ground, At least of injecting fluid into the periphery of the global fluid path layer (1) and recovering fluid from the periphery of the global fluid path layer (1) through the well-like structure (10) through the global fluid path layer (1) Fluid control by either one can be implemented.
[0065]
Here, the well-like structure (10) is configured by, for example, providing a plurality of strainer portions (11) communicating with the ground in the axial direction as described in [24], and at least each of the strainer portions (11). If one is arranged at a position communicating with the wide area fluid path layer (1), various fluid controls can be performed through the wide area fluid path layer (1) by the well-like structure (10). .
[0066]
Further, according to the soil contamination countermeasure system described in [21], as described above, the wide-area fluid path layer (1) is laminated in a state in which granular materials are densely gathered within a predetermined range. Thus, the wide-area fluid path layer (1) can be installed very easily.
[0067]
Further, according to the soil contamination countermeasure system according to [22], the wide area fluid path layer (1) protrudes in a substantially vertical direction from at least one of the upper and lower surface portions, and the wide area fluid path layer (1) and Similarly, the convex auxiliary structure (5) including a large number of gaps in a state in which the granular materials are densely gathered and communicating with the wide-area fluid path layer (1) is formed together. ], It is possible to construct a system capable of locally enhancing fluid injection and recovery around the auxiliary structure (5).
[0068]
Further, according to the soil contamination countermeasure system according to [23], the auxiliary structure (5) is recovered from the auxiliary structure (5) by including a material that promotes adsorption or decomposition of the pollutant. It is possible to positively adsorb the pollutants in the fluid to be collected, or to recover them while detoxifying them by decomposition, thereby further promoting the removal of the pollutants. In addition, from the viewpoint of cost reduction, only the local auxiliary structure (5) includes a material that promotes adsorption or decomposition of contaminants, and these substances are also included in the granular material forming the wide fluid path layer (1). May be included.
[0069]
In addition, the soil pollution control system forms the groundwater circulation system as described in [7], and also includes water treatment using aerobic metabolism of aerobic microorganisms as described in [9]. When performing, it is necessary to incorporate in the system in the device for preventing obstruction | occlusion by the proliferation microorganisms in the water collection part of the pump (40) used as the drive source of groundwater circulation.
[0070]
Therefore, by incorporating the configuration described in [25] above, the filtrate accumulated on the surface of the strainer (42) covering the water collecting part with the operation of the pump (40) is removed from the air supply path (17). Even if the separated filtrate is collected on the ground together with the aerated gas by the filtrate collection path (43) through the filtrate collection path (43), the groundwater contamination treatment using microorganisms as described above can be performed. It is possible to reliably prevent clogging due to sludge containing.
[0071]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, various embodiments representing the present invention will be described with reference to the drawings.
1 to 11 show a soil contamination countermeasure method and a soil contamination countermeasure system according to various embodiments.
1 and 2 show typical installation examples of the wide-area fluid path layer. The wide-area fluid channel layer 1 is installed so as to form an artificial stratum around the boundary between the underground saturated zone 2 and the unsaturated zone 3.
[0072]
The wide-area fluid path layer 1 is an artificial stratum that is expanded in a substantially horizontal direction within a predetermined range, is laminated in a state where granular materials are densely gathered, and includes a number of gaps communicating with each other. Here, specifically, the granular material corresponds to, for example, crushed stone, gravel and the like, but is not limited to a natural material and may be an artificial sphere or the like.
[0073]
The wide-area fluid path layer 1 includes a number of gaps that communicate with each other and expand three-dimensionally, and these gaps are open to the outside over the entire surface of the wide-area fluid path layer. It is good also as such a form. In addition, for example, when a block including a plurality of gaps is laid down or installed in a relatively narrow range, it can be formed as a sheet layer having a predetermined thickness including a plurality of gaps. is there.
[0074]
The saturated zone 2 is generally a soil zone below the groundwater surface W and the soil gap is saturated with moisture, and the unsaturated zone 3 is generally above the groundwater surface W and in the soil gap. It is a soil zone in which the water is unsaturated and gas is mixed. Below the saturation zone 2 is an impermeable layer R such as a basement rock or a clay layer.
[0075]
By installing the wide-area fluid path layer 1 around the boundary portion including the groundwater surface W, which is the boundary between the saturated zone 2 and the unsaturated zone 3, fluid control through the wide-area fluid path layer 1 is performed in the saturated zone 2 Both underground water existing and underground air existing in the unsaturated zone 3 can be targeted. The soil contamination countermeasure method according to the present invention includes at least one of injecting fluid around the wide area fluid path layer 1 and recovering fluid from the circumference of the wide area fluid path layer 1 through the wide area fluid path layer 1. Fluid control by means of
[0076]
The saturated zone 2 and the unsaturated zone 3 where the wide-area fluid channel layer 1 is installed are natural space segments having a predetermined layer thickness including the groundwater surface W between the upper and lower sides and extending in a plane. Classification is not limited to the state that exists in nature. For example, artificially set the division between the saturated zone 2 and the unsaturated zone 3 such as by shielding the surroundings of the pollution control area with a water shielding work, etc., that is, the height of the groundwater surface W If the length can be arbitrarily set, each zone section artificially set for pollution countermeasures is applied, and the wide-area fluid path layer 1 is installed around the boundary portion. The same applies to the case where the zone between the unsaturated zone 3 and the saturated zone 2 is artificially set by water injection / pumping into the ground.
[0077]
When constructing the wide-area fluid path layer 1, first excavate the soil in the upper zone of the unsaturated zone 3 and the saturated zone 2 in the construction target area, and then lay crushed stones, gravel, etc. Laminate to thickness. At this time, the crushed stones and gravel used for the upper and lower surfaces of the wide-area fluid path layer 1 are installed with a different particle size from that of the middle part of the wide-area fluid path layer 1, and the soil fluid path around the wide-area fluid path layer 1 It is better to prevent intrusion into the layer.
[0078]
For the same purpose, the upper and lower surfaces and sides of the wide-area fluid path layer 1 may be covered with a sheet having a mesh or the like. That is, as long as the wide-area fluid path layer 1 is covered by a method that prevents the invasion of soil while allowing the fluid to pass therethrough, it is not limited to the above example. After the installation of the wide area fluid path layer 1 is completed, the upper part is covered with soil 4. The basic shape of the wide-area fluid path layer 1 is not limited to the rectangular parallelepiped shape shown in FIG. 2, but is set to an appropriate shape each time depending on the situation of the pollution control target area.
[0079]
Further, the wide area fluid path layer 1 includes a large number of gaps in a state of protruding in a substantially vertical direction from at least one of the upper and lower surface portions thereof, and in the state in which the granular materials are densely assembled like the wide area fluid path layer 1. A convex auxiliary structure 5 communicating with the wide-area fluid path layer 1 may be formed together. The auxiliary structure 5 can locally enhance fluid injection and recovery through the wide-area fluid path layer 1 around the formation site.
[0080]
About the shape of the auxiliary | assistant structure 5, it can form in various shapes, such as cylindrical shape, strip | belt shape, a reverse cup shape, etc., It does not specifically limit. Moreover, the installation position and number of the auxiliary structures 5 are not particularly limited. The auxiliary structure 5 will be described later in detail.
[0081]
As shown in FIGS. 1 to 3, the soil contamination countermeasure system according to the first embodiment includes the above-described wide-area fluid path layer 1 and a well-like structure 10 installed so as to be able to communicate with the wide-area fluid path layer 1 from the ground. And comprising. This soil contamination countermeasure system includes the fluid injection into the periphery of the wide area fluid path layer 1 through the wide area fluid path layer 1 by the well-like structure 10 and the recovery of the fluid from the periphery of the wide area fluid path layer 1. The fluid control by at least one of them can be performed.
[0082]
The well-like structure 10 includes a plurality of strainer portions 11a and 11b that are openings communicating with the ground in the axial direction, and at least one of the strainer portions 11a and 11b is formed in the wide-area fluid path layer 1. It is arranged at a position to communicate. In the installation example shown in FIGS. 1 to 3, the upper strainer portion 11 b communicates with the wide-area fluid path layer 1 so that fluid can enter and leave the wide-area fluid path layer 1. Depending on the desired form of fluid control (for example, the case shown in FIG. 3), it may be sufficient to provide only one strainer portion 11 in the middle of the well-like structure 10.
[0083]
In the case where the fluid is recovered by suction using the well-like structure 10, a function that allows the inside of the well-like structure 10 to be airtight except for the strainer portions 11 a and 11 b is required. At that time, on the contact surface between the lower end of the well-like structure 10 and the soil and the soil, a sealing 12 is applied to fill the gap with bentonite or the like so as not to hinder suction.
[0084]
In addition, when the below-described groundwater circulation or the like is performed (for example, the case shown in FIG. 4), it is essential to provide a plurality of strainer portions 11 a and 11 b in the axial direction of the well-like structure 10. The inside of is partitioned by a packer 13 for each part corresponding to each strainer part 11a, 11b, and a circulation system is constructed through a pipe connecting the strainer parts 11a, 11b and water collecting means such as a pump.
[0085]
That is, the soil contamination countermeasure system includes a pipe that is inserted into the well-like structure 10 to connect the inside of the structure and the ground equipment, and ancillary equipment such as a pump that is connected to the pipe. The incidental facility is configured to enable fluid recovery / injection between the ground facility and the wide-area fluid path layer 1 through the well-like structure 10.
[0086]
Further, as the main incidental equipment of this soil contamination countermeasure system, as shown in FIG. 1, there are a vacuum pump 21, a liquid carry-out pump 22, a contamination treatment device 23, etc. for the purpose of fluid transfer. Used for pollution control using soil pollution control system.
[0087]
Specific examples of the contamination treatment device 23 include an aeration tower, an activated carbon adsorption tower, a resin / carrier filling tank, an oxidative decomposition tank, an oil / water separation tank, a membrane separation / filtration tank, a coagulation sedimentation tank, an aerobic treatment tank, This applies to brown gas treatment tanks. Furthermore, incidental facilities relating to fluid supply (injection) include a boiler, a compressor, an organic substance supply tank, a salt supply tank, a solvent supply tank, and the like.
[0088]
Ancillary facilities constituting such a soil contamination countermeasure system are not limited to the above-described devices and the like, and are appropriately selected each time depending on the contamination species and state. Although the number and size of the well-like structures 10 installed in the wide-area fluid path layer 1 are not particularly specified, it is not always necessary to provide a large number of holes as in the prior art. Needless to say, the minimum number and size may be set according to the groundwater circulation method.
[0089]
FIG. 3 shows a first embodiment of the present invention.
In the present embodiment, in the unsaturated zone 3, a fluid flow A mainly composed of gas that is opposite to the diffusion direction of the pollutant is formed by suction through the wide-area fluid path layer 1 and the well-like structure 10, and saturated. Prevents the diffusion of contamination from zone 2 to unsaturated zone 3. At the same time, the groundwater level is managed by pumping using the well-like structure 10 to prevent the diffusion of contamination to the unsaturated zone 3 due to a temporary rise in the water level caused by the seasonal fluctuation of the groundwater level.
[0090]
That is, in the well-like structure 10, the lower end of the strainer portion 11 b communicating with the wide area fluid path layer 1 is installed at a position lower than the natural groundwater level and higher than the lower surface of the wide area fluid path layer 1. A groundwater flow B for collecting contaminants in the saturation zone 2 by suction from the suction pipe 14 by installing the suction part of the suction pipe 14 fitted in the lower part of the lower end of the strainer portion 11b. Form. Then, the groundwater collected through the well-like structure 10 by driving the liquid carry-out pump 22 is detoxified by the pollution treatment device 23.
[0091]
On the other hand, in the case where contaminants are present in the unsaturated zone 3 above the wide-area fluid channel layer 1, contamination to the saturated zone 2 below the wide-area fluid channel layer 1 is performed by the same groundwater fluid control as described above. It can also be applied to prevent diffusion. That is, a part of the pollutant diffused downward from the unsaturated zone 3 is recovered as a gas by the fluid flow A mainly composed of gas formed by suction through the wide-area fluid path layer 1, and the permeation Contaminants that have infiltrated into the wide fluid path layer 1 together with water and the like are collected in the vicinity of the groundwater surface W by the groundwater flow B.
[0092]
As a result, the pollutant existing in the unsaturated zone 3 is collected by the well-like structure 10 through the wide-area fluid path layer 1 before being diffused into the deep part of the saturated zone 2 and is detoxified by the pollution treatment device 23. The The method for preventing the diffusion of contamination is not limited to the example described with reference to FIG. 3, and various fluid flows are formed through the wide-area fluid path layer 1, and the diffusing contamination is induced in the fluid flow. Any method of collecting may be used.
[0093]
By the way, in the present embodiment, the excavation of the unsaturated zone 3 is indispensable for the construction of the wide-area fluid path layer 1, but the soil used for the covering soil 4 to the upper part after the excavation is basically the same. Regardless of history. If the soil condition of the excavated soil is difficult to treat by simply collecting / injecting the fluid, it may be used as the cover soil 4 after being subjected to another contamination treatment, or a separate non-contaminated soil. It may be used for the covering soil 4 as the soil.
[0094]
In the case of soil that has been subjected to contamination treatment but is in the process of requiring time to complete the contamination treatment, for example, bioremediation using aerobic microorganisms or contamination desorption treatment using reaction heat is performed. When it is necessary to collect or inject fluid in the treatment process in the soil, it is preferable to perform the pollution repair / management by the wide-area fluid path layer 1 of the present invention and the fluid control therethrough. On the other hand, if the soil condition of the excavated soil can be contaminated by simply collecting / injecting the fluid, the excavated soil is backfilled as it is, and then the pollution repair / management using this embodiment is performed in the same manner. .
[0095]
As described above, the excavation of the unsaturated zone 3 is indispensable in connection with the construction of the wide-area fluid path layer 1, and the subsequent soil cover 4 prevents the soil layer from having a geological structure inside the wide-area fluid path layer 1. Is formed. Experiments have shown that the absence of this strata structure is advantageous for fluid aspiration in remediation of contamination by fluid recovery / infusion. That is, as a conventional pollution countermeasure, a large number of suction / injection wells arranged for each contaminated natural strata can be dealt with by unified suction using the wide-area fluid path layer 1 by destroying the natural stratum structure. became.
[0096]
At this time, by forming the convex auxiliary structure 5 that can partially enhance the fluid recovery / injection amount so as to communicate with the upper surface of the wide-area fluid path layer 1, it is possible to repair in accordance with the contamination state. This was clarified through experimental investigation. That is, the contamination concentration is grasped for each lot of excavated soil, the area is classified according to the contamination concentration on the wide-area fluid path layer 1, the covering soil 4 is backfilled, and the auxiliary structure 5 is formed according to the degree of contamination. As a result, the contamination treatment in the surroundings can be intensively performed, and more efficient repair is possible.
[0097]
The auxiliary structure 5 has a screen function partly or entirely, and is formed in a structure that allows fluid to pass through while preventing entry into the outside soil. If it is such a structure, a shape, a material, etc. will not ask | require in particular. Moreover, the inside of the auxiliary structure 5 is filled with crushed stones or gravel to the extent that the screen function is not impaired, and the shape of the structure is maintained. In particular, it is not limited to crushed stones or gravel. Further, as described above, the shape and the number of installed auxiliary structures 5 are not particularly limited as long as they can be in contact with any of the upper and lower surface portions of the wide-area fluid path layer 1 to form a fluid flow therein.
[0098]
The auxiliary structure 5 contains a material that promotes the adsorption or decomposition of contaminants, so that the contaminants in the fluid recovered from the auxiliary structure 5 can be actively adsorbed or recovered while detoxified by decomposition. And the removal of contaminants can be further promoted. Specific examples of the material include a carbonized product formed into a granular shape and reduced iron powder applied to the granular material. Carbonized products typified by so-called charcoal have an action of adsorbing pollutants, and reduced iron powder has a weak processing ability to dechlorinate organochlorine compounds such as trichlorethylene while having time. Are known.
[0099]
In addition, when the soil in the unsaturated zone 3 is contaminated with a high concentration of contamination and the contamination treatment is performed by suction of fluid, the contamination concentration should be made low and uniform in order to make the contamination concentration appropriate. It is advisable to carry out an appropriate contamination dispersion treatment as a pretreatment. As a specific method of the contamination dispersion treatment, for example, when covering the soil 4 after the construction of the wide-area fluid path layer 1, an operation of mixing the contaminated soil related to the covering soil 4 and averaging the concentration of the contaminant, or a customer The operation of mixing soil and averaging by lowering the contaminant concentration is effective.
[0100]
Each of the operations as the pollution dispersion treatment has been found based on the fact that it is considered mainly due to the inhibition of the metabolic reaction of microorganisms and the fact that there are few contact surfaces with gas as the rate-determining factors of restoration caused by high-concentration contamination. In addition, after such a contamination dispersion process, the contaminants in the contaminated soil are removed by fluid control through the wide-area fluid path layer 1, thereby enabling a more rapid contamination process. In addition, it is suggested that each operation as the contamination dispersion process is a technique that can be used not only for pretreatment of fluid control but also when performing biological / chemical treatment or physical treatment.
[0101]
Subsequently, regarding the soil contamination countermeasure method by the fluid control using the soil contamination countermeasure system comprising the wide-area fluid path layer 1 and the well-like structure 10 and its ancillary facilities, according to the similarity of the soil contamination mechanism of each pollutant As a result of classifying pollution and examining in detail soil pollution countermeasure methods suitable for each pollution countermeasure, the inventors have proposed a new soil pollution countermeasure system and soil pollution countermeasure method according to the following embodiments. Hereinafter, various embodiments optimal for each contamination will be described in detail.
[0102]
Of the contaminations contained in the soil, the contaminations that are particularly diffusible can be broadly divided into the following three contamination groups. One of these is “light non-aqueous pollution”, which has a relatively low solubility in water and a lighter specific gravity than water, and is represented by gasoline, including benzene, ethylbenzene, toluene, xylene, polycyclic aromatic compounds, and the like. It is known as a typical non-aqueous liquid pollution caused by a hydrocarbon-based mixture.
[0103]
These light non-aqueous pollutions contaminate the ground air and the strata in the underground infiltration process in the unsaturated zone 3, and after reaching the ground water surface W, move and diffuse on the surface of the water by the ground water flow. It is a diffusion of contamination.
[0104]
On the other hand, “heavy non-aqueous pollution”, which has a relatively low solubility in water and a higher specific gravity than water, is known, and is mainly due to organochlorine solvents. Specifically, tetrachloroethylene, trichloroethylene, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, 1,1-dichloroethylene, vinyl chloride, methyl chloride, dichloromethane, chloroform, carbon tetrachloride, 1,1-dichloroethane 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, etc. have been confirmed in heavy non-aqueous contamination. In addition, although there are few cases of contamination, 1,3-dichloropropene, 1,2-dichloropropane, chlorobenzene, dichlorobenzene, and the like are also suggested to possibly induce heavy nonaqueous contamination.
[0105]
These heavy non-aqueous pollutions contaminate underground air and the formation during the underground infiltration process in unsaturated zone 3, and then reach the ground water surface W, and some of them form heavy non-aqueous liquid reservoirs on the water surface. However, when a part of it further moves to the lower part of the saturation zone 2, it spreads and diffuses after being dissolved by the groundwater flow, and a part of it reaches the base of the saturation zone 2 to form a heavy non-aqueous liquid reservoir. This will release the pollution in the groundwater and cause the pollution to diffuse downstream.
[0106]
Furthermore, contamination with nitrate nitrogen and some cyanide, arsenic, heavy metal compounds, etc. is also known as contamination with relatively high water solubility and low adsorption to soil. These pollutions are dissolved and infiltrated in the underground infiltration process in the unsaturated zone 3 of rainwater, reach the groundwater surface W, and then move and diffuse along the groundwater flow.
[0107]
FIG. 4 shows a second embodiment of the present invention.
The right side of the well-like structure 10 in FIG. 4 shows an installation example of the wide-area fluid path layer 1 in the case where light nonaqueous liquid contamination is targeted for pollution countermeasures, and a typical example of the fluid flow direction through this. In pollution caused by light nonaqueous liquid pollution, the lower end of the upper strainer portion 11b of the well-like structure 10 communicating with the wide area fluid path layer 1 is lower than the natural groundwater level and higher than the lower surface of the wide area fluid path layer 1 Install in.
[0108]
The suction part of the suction pipe 14 in the well-like structure 10 is set lower than the lower end of the strainer portion 11b, and the suction pipe is used for collecting the non-aqueous liquid reservoir N1 floating on the ground water surface W in addition to the contaminated ground water and the contaminated underground air. Collect at 14. These contaminations are collected through the well-like structure 10 and then detoxified by the contamination treatment device 23. Moreover, from the strainer part 11a on the lower side of the well-like structure 10, the cleaning water K is injected through the injection pipe 15 to form a groundwater flow C that guides the contaminated water to the upper wide fluid path layer 1.
[0109]
Here, the water-impervious wall 30 is installed along the side portion of the wide-area fluid path layer 1, and the lower surface of the wide-area fluid path layer 1 is opened with a predetermined gap between the impermeable wall 30 and the impermeable wall 30. By setting the hardly permeable wall 31 in a partition shape along the part, the continuity in a predetermined direction in the soil is blocked or hardly penetrated. Thereby, the flow direction of the fluid in the fluid control through the wide-area fluid path layer 1 can be induced, and in particular, the suction effect can be improved by enhancing the airtightness at the time of fluid recovery.
[0110]
Further, the cleaning water K is preferably one that is not contaminated, but at least if the contamination is lighter than the contaminated groundwater, it can be used for cleaning purposes, and a part of the treated water that has passed through the contamination treatment device 23 is used. The groundwater circulation system may be constructed by using it as the cleaning water K again. Further, in order to enhance the cleaning effect, a solution to which a cleaning chemical solution is added may be used.
[0111]
By controlling the fluid through the wide-area fluid path layer 1, volatile contaminants existing in the unsaturated zone 3 are phase-shifted from the ground surface to the underground air flow D flowing toward the upper surface of the wide-area fluid path layer 1, After passing through the upper part of the road layer 1 toward the strainer portion 11b on the upper side of the well-like structure 10 and reaching the well-like structure 10 from this strainer portion 11b, it is finally recovered and removed by the ground equipment. The
[0112]
On the other hand, the light non-aqueous liquid reservoir N1 existing on the natural groundwater surface W is brought along the water level gradient toward the well-like structure 10 together with the groundwater by keeping the water level in the well-like structure 10 lower than the natural groundwater level. Then, after reaching the well-like structure 10, it is finally collected and removed by the ground equipment.
[0113]
The fluid recovery performed by the suction pipe 14 and the incidental equipment connected thereto is not limited to the above-described embodiment as long as the system and method can recover each fluid. In addition, the soil contamination caused by the light non-aqueous contamination is controlled by the fluid control using the wide-area fluid path layer 1 and the suction operation through the wide-area fluid path layer 1 is the main fluid operation, and the contaminated fluid is recovered. However, the method is not limited to the above-described embodiment.
[0114]
In addition, as a result of a detailed examination of the contamination treatment of the light non-aqueous liquid reservoir N1, by collecting groundwater through the wide-area fluid path layer 1 and leaching by air suction, it is possible to improve efficiency from the contaminated natural strata. Clarified that good recovery can be achieved.
The left side of the well-like structure 10 in FIG. 4 shows an installation example of the wide-area fluid path layer 1 when the light non-aqueous liquid reservoir N1 is particularly targeted for pollution countermeasures, and a representative example of the fluid flow direction through this. .
[0115]
In order to promote the exudation of the light non-aqueous liquid reservoir N1, the impermeable walls 31 are respectively installed along the upper and lower surface portions of the wide-area fluid path layer 1, and the suction of the fluid through the wide-area fluid path layer 1 is performed. Implement from natural strata section 6 where N1 exists. The exuded light non-aqueous liquid reservoir N1 is recovered from the upper strainer portion 11b in the well-like structure 10 through the groundwater flow below the wide-area fluid path layer 1. In this method, the wide-area fluid path layer 1 is installed so as to be in contact with the natural stratum having the light non-aqueous liquid reservoir N1, and leaching of the light non-aqueous liquid reservoir N1 by the suction operation and recovery by the groundwater flow are performed as fluid control. Any method may be used, and the present invention is not limited to the above-described embodiment.
[0116]
FIG. 5 shows a third embodiment of the present invention.
In the present embodiment, as a method other than the second embodiment for light nonaqueous liquid contamination in groundwater, groundwater flow through strainer portions 11a and 11b provided on the lower side and upper side of the well-like structure 10 is described. In addition, it is possible to carry out efficient air pollution remediation by phase shifting of pollutants to gas, aerobic metabolism by microorganisms, etc. is there.
[0117]
As shown in FIG. 5, the groundwater flow C is basically the same as that shown in the right side of FIG. 4, but the diffuser pipe 16 is provided above the saturation zone 2 filled with groundwater in the wide-area fluid channel layer 1. It differs from the second embodiment shown in the right side of FIG. 4 in that it is installed and the groundwater flow is set in an aerobic environment under an oxidizing atmosphere. The air diffuser 16 is installed on the upper side of the hardly permeable wall 31 so as to diffuse upward. The gas used for the air diffused from the air diffuser 16 only needs to contain molecular oxygen in addition to normal air, and ozone or the like is added as necessary as another coexisting gas.
[0118]
The gas diffused into the groundwater by the air diffuser 16 is a gas phase in the wide-area fluid path layer 1 and is sucked in the well-like structure 10 together with the gas flow sucked from the upper surface portion of the wide-area fluid path layer 1. Collected by tube 14. A part of the recovered gas may be returned to the aeration again, or the entire amount may be released to the atmosphere after being appropriately treated by the contamination treatment device 23. In order to promote the growth of microorganisms, a gaseous nitrogen source such as ammonia or nitrous oxide, or a nutrient solution containing a nitrogen source or the like may be supplied into the circulation system through the air diffuser 16.
[0119]
It is desirable that the air diffusion method be installed in the wide-area fluid channel layer 1 as shown in FIG. 5, but the present invention is not limited to this, and the existing observation well or the like is used secondarily and the lower part of the aquifer etc. You may go from. In that case, it is advisable to make an effort to prevent the diffusion of the contamination by assuming a range in which the air diffuses in advance and installing a wide-area fluid path layer 1 having a sufficiently wide area above it.
[0120]
The groundwater injected into the saturation zone 2 from the lower strainer portion 11a of the well-like structure 10 is recovered in the upper strainer portion 11b through the wide-area fluid path layer 1, and this recovered groundwater is shown in FIG. 4 may be discharged on the ground surface after the entire amount is subjected to appropriate treatment by the pollution treatment device 23 shown in FIG. Moreover, you may return the whole quantity or one part of the treated groundwater to the underground again, and may construct a groundwater circulation system.
[0121]
Alternatively, as shown in FIG. 5, the lower side through the water supply pipe 41 penetrating the packer 13 by the operation of the submersible pump 40 installed in the upper section of the upper and lower sections partitioned by the packer 13 in the well-like structure 10. The groundwater circulation system may be constructed again by supplying a part of the collected groundwater to the section and injecting the groundwater into the saturation zone 2 again from the strainer portion 11a in the lower section. .
[0122]
In particular, when there is no light non-aqueous liquid contamination reservoir N1 (see FIG. 4), intake through the well-like structure 10 is dedicated to gas suction, and groundwater is partitioned by the packer 13 using an underwater pump 40 or the like. A circulation system is formed by transferring from the upper side of the well-like structure 10 to the lower compartment, and contamination treatment is performed by microbial decomposition in the circulation system. Contamination treatment by microbial decomposition is particularly suitable for the decomposition of petroleum hydrocarbons such as benzene.
[0123]
When constructing a circulatory system in the underground, it is necessary to incorporate measures against blockages caused by microbial growth in the groundwater catchment section, taking into account the step of promoting the growth of microorganisms in the circulatory system. . That is, in the present embodiment shown in FIG. 5, the amount of ozone gas diffused from the air diffuser 16 is appropriately controlled by a control device (not shown) for the purpose of controlling the amount of microorganisms, and the well-like structure 10 An automatic cleaning device is installed. This automatic cleaning device clogs the water collecting portion 40a of the submersible pump 40 that injects ground water collected from the upper strainer portion 11b of the well-like structure 10 into the soil from the lower strainer portion 11a. It is to prevent.
[0124]
More specifically, the automatic cleaning device covers the water collecting portion 40a of the submersible pump 40 with a strainer 42 that filters groundwater collected from the water collecting portion 40a, and an air supply pipe (air supply path) that can be ventilated from the ground. 17 is inserted into the well-like structure 10, and the lower end outlet of the air supply pipe 17 is arranged at a position facing the inside of the strainer 42 from the water collection part 40 a side, and a filtrate collection pipe (filtrate that communicates to the ground) The recovery path) 43 is inserted into the well-like structure 10, and a large-diameter recovery portion 44 that communicates with the filtrate recovery pipe 43 in a state of surrounding the strainer 42 is connected to the lower end of the filtrate recovery pipe 43. Configured.
[0125]
The air supply pipe 17 and the filtrate collection pipe 43 have a double pipe structure, and the filtrate collection pipe 43 is formed in an outer cylinder shape surrounding the air supply pipe 17. Moreover, the drainage part which is the connection port of the water collection part 40a of the submersible pump 40 and the said water supply pipe 41 is each installed in the well-like structure 10 so that it may exist under a groundwater surface.
[0126]
During normal groundwater circulation operation, the microbial conglomerate is filtered by the strainer 42 covering the water collecting part 40a of the submersible pump 40, and the groundwater as filtrate is injected into the saturation zone 2 from the strainer part 11a below the well-like structure 10. Is done. On the other hand, with the passage of time, microbial agglomerates accumulate on the surface of the strainer 42 of the submersible pump 40, reducing the water absorption performance of the submersible pump 40 and increasing the load of the submersible pump 40.
[0127]
When the load on the submersible pump 40 exceeds a certain level, the operation of the submersible pump 40 is automatically stopped by a control device (not shown), and the movement of water around the strainer 42 is temporarily interrupted. 17, a gas such as compressed air may be ventilated from the inside of the strainer 42 of the submersible pump 40, and an automatic operation may be performed to peel off the microbial conglomerate accumulated on the outer surface of the strainer 42.
[0128]
On the other hand, the gas that has moved to the outside of the strainer 42 due to the ventilation from the air supply pipe 17 is directed upward inside the large-diameter collection unit 44 that communicates as it is. It goes upwards through the filtrate collection pipe | tube 43 connected to the large diameter collection | recovery part 44 connected, involving the groundwater containing an agglomerate. Eventually, the groundwater containing the gas that has reached the ground and the separated microbial conglomerate is collected.
[0129]
By the automatic operation of the automatic cleaning apparatus as described above, the microbial conglomerate is appropriately processed, and the above-described ground water circulation operation can be continuously and stably performed. In addition, the automatic cleaning apparatus has a function of collecting microorganism agglomerates and the like on the ground by filtering the microorganism agglomerates and the like and separating them with gas in the groundwater circulation operation. The integrated automatic driving system is not limited to the above-described configuration. In addition, it can be applied to a separate treatment method that collects heavy metals and nitrate nitrogen in the groundwater by microorganisms and then collects them on the ground using this device. What is necessary is just to utilize the function of this apparatus.
[0130]
Further, as in this embodiment, the method for purifying pollution under aerobic conditions using aeration in the groundwater system is limited to light non-aqueous liquid pollution typified by petroleum hydrocarbons such as benzene. However, it has already been confirmed through experiments that it is an effective countermeasure against many pollutants such as heavy nonaqueous liquid pollution and nitrate nitrogen. However, in the case of heavy non-aqueous pollution, rather than trying to decompose microorganisms, it is preferable to use a method of phase-shifting to a gas by aeration and recovering this pollution as a gas. Good treatment is possible by increasing the frequency of other backwashing and filtration treatments and implementing countermeasures against clogging without adding them.
[0131]
So far, the soil contamination countermeasure method and its system by various fluid control using the wide-area fluid path layer 1 in the case of pollution due to light non-aqueous pollution has been described. The soil pollution countermeasure method and its system for pollution caused by pollution will be described in turn below.
[0132]
Contamination due to heavy non-aqueous contamination can be dealt with by the same fluid control as contamination due to light non-aqueous contamination. However, in the area where there is a heavy non-aqueous liquid reservoir around the base of the saturation zone 2 located near the contamination center, the fluid using the wide-area fluid path layer 1 is separated after the surrounding area is separated by a water shielding work, etc., and the groundwater is extracted. The heavy non-aqueous liquid reservoir is collected by implementing the control.
[0133]
When the heavy non-aqueous liquid reservoir is at the base of the saturation zone 2 and the infiltration of contaminants from the base into the impermeable layer R is slight, as shown in FIG. 6 and FIG. A fluid flow is formed by the cleaning liquid F, etc., and the volatilization of the heavy non-aqueous liquid reservoir N2 on the surface of the base of the saturation zone 2 is promoted. Contamination countermeasures are implemented by fluid control through the object 5.
[0134]
FIG. 6 shows a fourth embodiment of the present invention.
In the present embodiment, a fluid operation mainly using gas is performed using hot air E. The heat supply pipe 18 is inserted into the well-like structure 10, and the lower end outlet of the heat supply pipe 18 is connected to the well-like structure 10. The strainer portion 11a on the lower side of the well-like structure 10 extends to a certain section, and hot air E is injected into the soil in the saturation zone 2 from the strainer portion 11a through the heat supply pipe 18.
[0135]
The hot air flow generated by the injection of the hot air E promotes volatilization of the heavy non-aqueous liquid reservoir N2, and volatilizes by the gas suction operation through the convex auxiliary structure 5 and the wide-area fluid path layer 1 connected to the upper part thereof. Contaminants are collected from the upper strainer portion 11b of the well-like structure 10. The contaminant collected to the ground through the suction pipe 14 is subjected to adsorption or decomposition processing by the contamination treatment device 23 or the like. In the present embodiment, a water shielding wall 30 extending to a position higher than the groundwater surface W is installed along the periphery of the wide area fluid path layer 1.
[0136]
FIG. 7 shows a fifth embodiment of the present invention.
In the present embodiment, a fluid operation mainly using liquid is performed using the thermal cleaning liquid F, and the heat supply pipe 18 is inserted into the well-like structure 10 in the same manner as described above. The lower end outlet of 18 extends only to the section where the upper strainer portion 11b of the well-like structure 10 is located, and instead, the lower end outlet of the suction pipe 14 extends to the section where the lower strainer portion 11a is present. Then, through the heat supply pipe 18, the hot cleaning liquid F, not the hot air E, is supplied from the upper strainer portion 11 b to the soil in the saturation zone 2 via the wide fluid path layer 1 and the auxiliary structure 5 extending downward from the lower surface portion. Inject into.
[0137]
Recovery of the heavy non-aqueous liquid reservoir N2 is promoted by the hot water flow generated by the injection of the thermal cleaning liquid F, and contaminants are removed from the well-like structure 10 by the pumping operation in the strainer portion 11a on the lower side of the well-like structure 10. It collects together with the groundwater from the lower strainer section 11a. Contaminants collected to the ground through the suction pipe 14 are processed by the contamination processing device 23 and the like.
[0138]
Specific components of the thermal cleaning liquid F supplied to the heat supply pipe 18 are not particularly limited, but it is desirable to add components that emulsify contamination such as surfactants and promote recovery by a fluid flow. Also in the present embodiment, the impermeable wall 30 is installed so as to extend along the periphery of the wide-area fluid path layer 1 to a position higher than the groundwater surface W, and a part of the auxiliary structure 5 is It is in contact with the inner wall of the underground water surface W.
[0139]
On the other hand, when the infiltration of the pollutant into the impermeable layer R is remarkable, a heating solution containing a peroxide having a specific gravity higher than that of water is injected into the contaminated soil, and the infiltration of the chemical solution into the impermeable layer R is attempted. It is effective to promote vaporization of the heavy non-aqueous liquid reservoir N2 by volatilization due to the reaction heat accompanying oxidation, and to recover the volatilized pollutant as a gas by suction through the lower surface of the wide-area fluid path layer 1. Experiments have shown that hydrogen peroxide is particularly suitable as an oxide.
[0140]
The fluid control in such a method is basically the same as the method described with reference to FIG. 6, but the heated solution containing peroxide is intermittently injected instead of the hot air E. Thereafter, the vaporized heavy non-aqueous liquid substance can be recovered by suction through the convex auxiliary structure 5 and the wide-area fluid path layer 1 by reaction heat accompanying oxidation.
[0141]
In addition, the hydrogen peroxide has been described as an example of a peroxide. However, there are other uses of a heating solution containing a perinorganic acid such as permanganic acid or persulfuric acid or a perorganic acid such as peracetic acid as a component. Is possible. However, the use of other than hydrogen peroxide mainly involves direct decomposition of the pollutant rather than vaporization of the pollutant, and also requires soil clogging with the remaining components, recovery and washing of the remaining components after the reaction, etc. The overall operation is complicated compared to the case of hydrogen peroxide. It is desirable to apply these uses as alternatives when the use of hydrogen peroxide is restricted in accordance with the situation of the pollution control area.
[0142]
In addition, the injection of the chemical solution is not limited to the injection using the well-like structure 10 in particular, and any method can be used as long as the chemical solution can be injected into the base of the saturated zone 2 where the heavy non-aqueous liquid reservoir N2 exists. However, the present invention is not limited to the fifth embodiment. In addition, it is necessary to consider the influence etc. with respect to the material of the heat supply pipe | tube 18 by a chemical | medical solution, It is necessary to select the injection | pouring method according to a chemical | medical solution.
[0143]
Subsequently, the wide-area fluid path layer 1 is used in the case of pollutants having high solubility in water and low adsorption to soil, specifically, for example, contamination of nitrate nitrogen or some heavy metals. The soil contamination countermeasure method and its system by various fluid control which was done are explained.
[0144]
For such pollutants with high solubility in water and low adsorptivity to soil, inhalation in the wide fluid path layer 1 is performed in parallel with water injection from the lower part of the saturation zone 2 and the surface part. Then, operation and construction for inducing pollutants to the wide fluid path layer 1 are taken in. In addition, when using a chemical such as a surfactant, chelating agent, acid or alkali to suspend or extract soil pollutants in water, or to treat heavy metals or other alkylation due to chemicals or microbial action, etc. In the case of performing processing for promoting the transfer of contaminants to water or gas by functional group modification or the like, the contamination processing can be performed by the method according to the following embodiment.
[0145]
FIG. 8 shows a sixth embodiment of the present invention.
In the present embodiment, water or a liquid such as a chemical solution that does not contain contaminants is sprinkled from above the unsaturated zone 3 through the sprinkler pipe 19 installed on the ground surface, and the unsaturated zone 3 due to underground penetration of the wash water is used. In addition to performing cleaning, suction through the wide-area fluid path layer 1 is performed to promote underground penetration of the cleaning water to enhance the cleaning effect and to collect pollutant gas.
[0146]
Also, the cleaning of the saturation zone 2 is shown on the left side with the well-like structure 10 in FIG. 8 by injecting washing water into the soil from the strainer portion 11a or 11b on the upper or lower side of the well-like structure 10. Cleaning is performed by forming a groundwater flow from the upper part to the lower part or from the lower part to the upper part shown on the right side of FIG.
[0147]
In the cleaning of the saturation zone 2, the auxiliary structure 5 extending downward from the lower surface portion of the wide-area fluid path layer 1, the impermeable wall 30, the hardly permeable wall 31, and the like are installed as necessary, and the cleaning is performed. Washing with the groundwater flow is performed after increasing the water recovery efficiency. In such a washing process, the washing wastewater collected on the ground is then subjected to appropriate pollution treatment on the ground, but a part of the treated wastewater is reused as washing water and supplied to the groundwater system again. A system may be constructed as follows. In particular, when performing extraction processing using a drug or the like, it is possible to reduce processing costs by removing only contamination and reusing a solution containing the drug.
[0148]
On the other hand, among the above-mentioned pollutants with high water solubility and low adsorptivity to the soil, those that are easily decomposed by microorganisms and the like form not only the soil pollution countermeasure method described above but also the groundwater circulation system. It is also desirable to include a process that incorporates operation and construction to promote substance conversion by microbial metabolism. Such a process can be dealt with by the same measures as the method for treating the light non-aqueous substance described in FIG. 5 by the groundwater circulation system in an oxidizing atmosphere.
[0149]
In addition, not only in an aerobic oxidizing atmosphere, but also in an anaerobic reducing atmosphere, various pollutants that have high solubility in water and low adsorptivity to soil by fluid control through the wide fluid path layer 1 It was confirmed by experiment that the decomposition of can be achieved. That is, in the groundwater circulation system formed by the fluid control through the wide-area fluid channel layer 1, an anaerobic reducing atmosphere was set, and detailed examination of the degradation of pollutants in such an environment was conducted as follows. It has been clarified that the contamination treatment can be performed by the method according to the embodiment.
[0150]
FIG. 9 shows a seventh embodiment of the present invention.
In the present embodiment, the well-like structure 10 having three strainer portions 11a, 11b, and 11c provided at predetermined intervals in the axial direction is used, and the hardly permeable wall 32 and the reducing substance containing portion 33 are provided. By appropriately installing, the fluid flow generated by the fluid control is guided in a predetermined direction.
[0151]
The inside of the well-like structure 10 is partitioned by a packer 13 into three sections according to the portions where the strainer portions 11a, 11b, and 11c are present, and the lower end outlet of the suction pipe 14 that directly extends from the vacuum pump 21 on the ground. Are arranged above the groundwater level in the section where the upper strainer portion 11b is located. Further, a submersible pump 40 equipped with an automatic cleaning device similar to that of the third embodiment described with reference to FIG. 5 is installed in the well-like structure 10 where the central strainer portion 11c is located.
[0152]
In the well-like structure 10, the water supply pipe 41 of the submersible pump 40 installed in the central section extends downward and penetrates the packer 13 and communicates with the lower section. Another submersible pump 40 is also installed in the lower section, and a water supply pipe 41 of the submersible pump 40 extends upward and penetrates the two packers 13 to communicate with the upper section.
[0153]
The groundwater circulation system collects groundwater from the strainer portion 11c in the center of the well-like structure 10 and passes through the submersible pump 40 installed in the central section of the well-like structure 10 to the lower side in the well-like structure 10. Sent to the segment. A part of the groundwater sent to the lower section is sent to the upper section of the well-like structure 10 by the submersible pump 40 installed in the lower section of the well-like structure 10, and the upper strainer. The remaining groundwater is injected into the soil in the saturated zone 2 from the lower strainer portion 11a through the portion 11b.
[0154]
By repeating such movement of groundwater, a groundwater circulation system is formed. In order to guide the fluid flow of the groundwater circulation system in a predetermined direction, a hardly permeable wall 32 is installed along the lower surface portion of the wide-area fluid path layer 1, A reducing substance-containing portion 33 having a tapered shape that is inclined downward in an inverted conical shape toward the axial center of the well-like structure 10 located at is provided.
[0155]
Unlike the substantially horizontal thick plate-like hardly permeable wall 31 described in each of the above embodiments, the hardly permeable wall 32 in the present embodiment rises upward in the wide-area fluid path layer 1 from the outer peripheral edge. It has a flange portion 32a. The reducing substance-containing portion 33 is a construction for maintaining the groundwater system in a reducing atmosphere, and has an inverted conical shape as described above so as to face the hardly permeable wall 32 in the wide-area fluid path layer 1. is set up. The reducing substance includes reduced iron powder, sugar, alcohol and the like.
[0156]
Further, in order to grow anaerobic microorganisms in the above-described groundwater system in a reducing atmosphere, a wide-area fluid path layer 1 is used to add a growth substrate such as alcohol using a nutrient solution supply device 50 or a nutrient solution supply tank 51 as necessary. It is configured so as to promote contamination treatment by the soil contamination countermeasure method and system. Here, the growth substrate is not limited to alcohol, and may be any carbon compound that promotes the growth of microorganisms, and any carbon compound that is useful for selectively growing a group of microorganisms that efficiently metabolize pollutants. Therefore, more effective processing can be achieved.
[0157]
According to the experiments by the inventors, the soil pollution countermeasure method according to the seventh embodiment is dissolved in groundwater in addition to contamination with high solubility in water such as nitrate ions and low adsorption to soil. It was also effective against light non-aqueous contamination and heavy non-aqueous contamination. Of these pollutants, in the case where a substance that can be a growth substrate for microorganisms is to be treated, the supplementary addition of the growth substrate described above is not required.
[0158]
If necessary, a water-impervious wall 30, a hardly permeable wall 32, and the like are installed to perform contamination treatment for increasing the efficiency of circulating water recovery and suction at the upper part of the wide-area fluid path layer 1. The soil contamination countermeasure method using the groundwater circulation under the anaerobic reduction atmosphere described above is not limited to the embodiment shown in FIG. 9, and a reducing substance is used as a part of the wide-area fluid path layer 1. Any part may be used as long as a groundwater circulation system can be formed in an anaerobic reducing atmosphere through addition of the part, and contamination removal can be achieved by microbial metabolism or the like.
[0159]
In addition, in the groundwater contamination treatment that promotes the growth of microorganisms, when the wide-area fluid path layer 1 is installed in the main flow of the contaminated groundwater flow and the treatment including the contaminated groundwater flowing down is performed, as shown in FIG. The height of the upper edge of the upstream and downstream impermeable walls 30 is set lower than the water level of the natural groundwater flow, the groundwater enters the system from the upstream, and the groundwater is discharged from the downstream to the outside. Set as follows. At this time, an adjustment processing unit 52 for minimizing the outflow of bacteria and contaminated secondary metabolites grown in the system to the outside of the processing system is installed in the system.
[0160]
As an example of the method shown in FIG. 9, the wide-area fluid path layer 1 is surrounded by a water-impervious wall 30, and a diffuser pipe 53 is installed below the saturated portion in the wide-area fluid path layer 1 in the enclosure. By sufficiently supplying air to the adjustment processing unit 52, the growth of protozoa and the microbial degradation of secondary metabolites are promoted, and the number of bacteria is actively reduced by predation of bacteria by the protozoa. This shows how to discharge groundwater after treatment.
[0161]
By the way, the groundwater circulation system shown in FIG. 9 does not simply complicate the groundwater flow, but the artificial stratum as the wide-area fluid path layer 1 is formed by impervious water due to the impermeable walls 30, the impermeable walls 31, 32, and the like. In addition, by partitioning with water-impervious construction, a plurality of reaction parts are formed, and countermeasures against contamination are implemented. Here, although the reaction part is divided in the underground by the said poorly water-permeable or water-impervious construction, it is formed so that it can communicate with each other. By allowing a series of fluid flows to pass through each of these reaction sections, a contamination treatment system in which the reaction sections are connected is constructed. In addition, simply installing a box-like structure or the like having fluid permeability in part is also an alternative to the partitioning described above. If the box-like structure is used, it becomes possible to easily incorporate a more complicated flow path setting, water treatment carrier / device, etc. into the underground fluid system.
[0162]
Such a pollution treatment system complements the functions of the conventional water treatment plant connected to the reaction tanks, tanks and pipes that have been carried out on the ground until now. It is based on a new idea that has made a leap from the idea of the prior art that was regarded as the target. This is not limited to the above-mentioned contamination countermeasures against the specific pollutants, but represents a new groundwater treatment concept that can be applied to many other pollution treatments or groundwater treatments.
[0163]
In addition, based on such a concept, as a soil contamination countermeasure method and system, a plurality of reaction units can be obtained by partitioning the natural fluid layer and the wide-area fluid path layer 1 with the impermeable walls 30 and the hardly permeable walls 31 and 32. A countermeasure method for forming a pollution treatment system by injecting and collecting groundwater through the wide-area fluid path layer 1 using the well-like structure 10 and taking measures for pollution, or recovering gas through the wide-area fluid path layer 1 As long as it is a countermeasure method for preventing pollution, it is not limited to the examples according to the above-described embodiments.
[0164]
For example, if the saturation zone 2 below the wide-area fluid channel layer 1 has three aquifers in the formation section, four strainers 11 described above are provided in the well-like structure 10 in the axial direction. In some cases, a circulation system is formed through the wide-area fluid path layer 1 and the auxiliary structure 5, or three well-like structures 10 having two strainer portions 11 are installed to form a pollution treatment system. good.
[0165]
In addition, a circulation system having a water flow from the upper part to the lower part and a circulation system having the opposite water flow are brought close to each other, and injection and pumping are carried out as a set in the same formation including the wide-area fluid channel layer 1, May be formed. Furthermore, a more complex and multifunctional soil contamination countermeasure method and system may be constructed by providing a number of partitions for poorly permeable construction by the hardly permeable wall 31, the hardly permeable wall 32, or the like. Further, from the same viewpoint, the above-mentioned soil contamination countermeasures can also be achieved by installing a plurality of wide-area fluid path layers 1 and the like so as to be separated from each other and further communicating with each other the systems constructed for each wide-area fluid path layer 1 and the like. Build a method and system.
[0166]
So far, among the pollutants, the contamination groups that are particularly diffusive to contamination can be broadly divided into three groups, and various embodiments in pollution countermeasures using the wide-area fluid path layer 1 have been described for each pollution group. In actual soil contamination, it is often the case that these contamination groups exhibit a combined pollution pattern. In such a case, what is necessary is just to cope with the application driving | operation implementation which combined the various methods mentioned above according to the aspect of a specific contamination. Even if the contaminants are the same, it is possible to improve the efficiency of the contamination process by appropriately selecting a countermeasure method according to the contamination concentration and the contamination site.
[0167]
Most in-situ pollution repair methods are based on promoting contamination treatment by moving fluid through the soil gap and mixing materials using it. In the prior art, fluid movement such as injection and pumping is carried out within a very local influence range by a fluid movement method using a well like a point or a line, and the fluid movement using a well is naturally limited to that fluid. As a result, the contamination that can be dealt with was also limited.
[0168]
Therefore, the contamination is recognized in various pollution forms in cases and complex formations where complex pollution is recognized, for example, ground air, ground water, soil, heavy non-aqueous pollution reservoir and various pollution forms such as heavy non-aqueous contaminants. In such cases, it was necessary to deal with each case individually, such as arranging a well group for each contamination site and form.
[0169]
In the fluid control using the wide-area fluid path layer 1 according to the present invention, the upper and lower surfaces of the wide-area fluid path layer 1 have a horizontal spread and can be repaired in a wide range of influence. Further, the present invention is characterized in that the movement of both gas and liquid fluids can be carried out simultaneously, and overcomes the problems of the prior art.
[0170]
At the same time, as a result of detailed examination of the pollution control method by the fluid control using the wide-area fluid path layer 1, the wide-area fluid path layer 1 was used for complex pollution as well as repair according to the pollution form. Through fluid control based on unified fluid movement, the inventors have invented various novel soil contamination countermeasure methods and systems that enable restoration of contamination.
[0171]
However, depending on the temperature conditions of the contaminated area and the nature of the soil, the volatility of the pollutants and the transferability to water are not sufficient, and it may be difficult to apply the present invention to all pollutants as they are. The For example, organic chlorine compounds such as PCB and dioxins, some heavy metals and agricultural chemicals, etc., and these pollutants remain in the topsoil near the contaminated intrusion, and are considered to be less mobile due to infiltration and groundwater . In the case of complex contamination with these contaminants, it is desirable to deal with them by an applied operation in which a separate contamination countermeasure method and the present invention are combined.
[0172]
In addition, the present invention is not only applied to contaminated land, but it is also desired to apply the present invention from a preventive standpoint of contamination diffusion to land where contamination may occur in the future. For example, when nitrogen-containing fertilizer is used in cultivated land such as farmland, it has been pointed out that excess nitrogen can penetrate into the underground and induce groundwater contamination as nitrate nitrogen contamination.
[0173]
In such a case, when the cultivated land is created, or when the wide-area fluid path layer 1 and the well-like structure 10 and the incidental facilities according to the present invention are installed in advance during the agricultural off-season, etc. Take the measures described above according to the contamination. This is not limited to cultivated land, but is intended for sites or planned sites that handle substances containing pollutants and their precursors, such as gas stations.
[0174]
Even if contamination occurs after the installation, it is possible to minimize the damage caused by the diffusion of contamination to the surroundings by the soil contamination countermeasure method and system of the present invention. In addition, even when full-scale pollution repair is necessary, the ground-based business facilities remain as they are, and the wide-area fluid path layer 1, the well-like structure 10 and the incidental facilities that have been installed in advance are used for the raw materials corresponding to the pollution. It is only necessary to perform position repair, and the risk of contamination can be reduced without interfering with operation. By applying the present invention to land where there is a possibility of contamination in the future, it is possible to reduce the burden on pollution prevention and pollution business operators.
[0175]
In addition, as mentioned above, it is not limited to implementation mainly at the pollution-causing site or a potential future location, but a simpler measure is mainly used at a location that is likely to become a contaminated site or a future contaminated site. Can minimize contamination damage. That is, the wide-area fluid path layer 1 and the auxiliary structure 5 attached thereto can be applied as a means for preventing pollution damage caused by the groundwater flow against pollution that diffuses due to groundwater flow.
[0176]
10 and 11 show an eighth embodiment of the present invention.
10 shows a longitudinal section, and FIG. 11 shows a transverse section. In the present embodiment, the inside or part of the impermeable wall is easily in contact with the basement of the area surrounded by the impermeable wall 30 with the wide fluid path layer 1 and the convex auxiliary structure 5. Install a permeable part. In the illustrated example, the convex auxiliary structure 5 extends upward over the entire circumference of the upper surface portion of the wide-area fluid path layer 1, and the easily water permeable portion has a cup shape.
[0177]
Further, by opening a part of the impermeable wall 30 at the point where the natural groundwater level is highest around the outer periphery of the impermeable wall 30 as an open wall 34 that can communicate with the outer side, it is easy to form a cup shape. The groundwater level W2 of the permeable portion is installed so as to be kept at the same level as or higher than the highest level of the natural groundwater level W1 around the outside of the impermeable wall 30. Due to the difference in water level between the inside and outside of the impermeable wall 30, it is possible to prevent infiltration of contaminants existing around the outside of the impermeable wall 30. Further, instead of providing the open wall 34, a liquid such as non-contaminated water or washing water is separately injected into the inside of the impermeable wall 30 so as to maintain the above-described difference in water level between the inside and outside of the impermeable wall 30. May be set.
[0178]
The function of maintaining a good groundwater flow inside the impermeable wall 30 by installing the wide-area fluid channel layer 1 and the auxiliary structure 5 responds to sudden changes in the external natural water level due to rainfall infiltration, etc. 30 greatly contributes to keeping the water level equal to that of the open wall 34. In addition, even if the auxiliary structure 5 is partially blocked, the cup-shaped easy-permeability portion serves as a bypass for the wide-area fluid path layer 1 and conducts groundwater throughout the inner surface of the impermeable wall 30. And the groundwater level inside the impermeable wall 30 can be stably maintained at a predetermined level.
[0179]
In general, the main medium for the diffusion and infiltration of contamination is groundwater, and measures are taken to prevent diffusion and infiltration by applying a water barrier. However, coupled with technical perfection, installation environment, and aging of the water-impervious structure over time, perfect water-blocking is often technically difficult. It also suggests that migration may occur.
[0180]
The pollution diffusion prevention method by controlling the groundwater level using the wide fluid path layer 1 according to the present invention and the convex auxiliary structure 5 connected thereto complements the diffusion prevention by the simple water-impervious technique used for current pollution countermeasures. Therefore, the present invention provides a simple and more precise method for preventing contamination diffusion to the market.
[0181]
In the eighth embodiment, the groundwater filled in the convex auxiliary structure 5 is provided through a partially opened open wall 34 at a point where the natural groundwater level is high. If the groundwater that leads to the inside is contaminated or if there is a possibility that the contamination will flow down in the future, non-contaminated water is separately injected into the auxiliary structure 5 or the contaminated groundwater passes through the open wall 34. Auxiliary operations such as applying appropriate contamination before and after passing are necessary. As a result of detailed examination of the latter, as a pollution countermeasure method, the inside of the auxiliary structure 5 is appropriately obtained by using a granular material that promotes the adsorption or decomposition of contamination and combining the contamination treatment method with passage. It was confirmed that the water quality could be maintained.
[0182]
In FIG. 10 and FIG. 11, the thing provided with the granular contamination processing substance containing part 35 is shown as an example. Here, reduced iron powder etc. are mentioned as a particulate contamination processing substance. In the present method, the reduced iron powder is known to have a weak processing ability to dechlorinate organochlorine compounds such as trichlorethylene, although it takes time, and the amount of groundwater in and out of the impermeable wall 30 is small. Is a method capable of effectively treating organic chlorine compound contaminated water.
[0183]
In the figure, although the particulate contamination processing substance containing part 35 is locally installed in the site | part along the said open wall 34, the installation place is not limited to the illustrated example. As long as it is installed at least around the open wall 34, it may be installed partially or entirely in the auxiliary structure 5 and the wide area fluid path layer 1, and is not particularly limited. Moreover, although reduced iron powder was mentioned as an example, use is not limited to this, A suitable granular pollution control substance is selected according to the contamination condition.
[0184]
Regarding the soil contamination countermeasure method and its system according to the present invention, the application to land where contamination is observed does not matter whether the pollution countermeasure target area is a pollution cause area or a contaminated area. As is often seen in industrial areas, it can also be applied to cases that are both pollution-causing and contaminated areas. In such a case, it is desirable to apply the present invention in a series for both purposes of preventing pollution from the pollution control target area and preventing re-contamination due to contamination diffusion from the outside. In FIG. 10, the wide-area fluid channel layer 1 exists below the natural groundwater level. This lowers the water level inside the impermeable wall 30 to the wide-area fluid channel layer 1 part and prevents the pollution damage after performing the pollution repair. It is an example which shows the condition which took the means and implemented the said operation in series.
[0185]
In addition, the present invention enables a series of pollution countermeasures according to the various embodiments described above by the wide-area fluid path layer 1 and the fluid control therethrough. An understanding of the current situation through pollutant analysis and environmental analysis is indispensable for the decision. Through these analyses, we will implement pollution countermeasures according to the degree of pollution and environmental conditions.
[0186]
The drawings and examples according to the various embodiments described so far represent the outline of typical construction and operation, and the soil pollution countermeasure method and the soil pollution countermeasure system according to the present invention are represented by It is not limited to these above. Needless to say, supplementary work for efficiently implementing the fluid dynamic control mentioned above, such as water shielding work and asphalt construction, should be carried out according to the situation of each pollution control area. The various embodiments described above are not limited by the presence or absence of these incidental constructions.
[0187]
【Example】
Hereinafter, based on FIG. 12 to FIG. 25, a purification test apparatus for experimentally confirming the pollution countermeasure effect by the implementation of the soil pollution countermeasure method and the soil pollution countermeasure system according to the various embodiments described above, and the same are used. The experimental results will be described.
[0188]
FIG. 12 is a front view schematically showing a medium-scale purification test apparatus.
The main body tank 100 of the present apparatus has a width of 210 cm, a height of 100 cm, and a depth of about 20 cm. The main body tank 100 is composed of two symmetrical tanks with a central partition 101 in between. Well-like structures 110A and 110B are provided above and below, and a water level adjusting cylinder 200 is provided on the side wall surface.
[0189]
Further, in the main body tank 100, the height portion where the strainer portion 111 of the upper well-like structure 110 </ b> A is located is filled with crushed stone having a particle diameter of 4 to 20 mm to simulate the wide-area fluid path layer 1. The upper surface portion was filled with fine sand through a stainless mesh, and the lower surface portion was filled with medium sand.
[0190]
The inflow and outflow of the fluid in the main body tank 100 are incidental equipment groups 211 and 212 that are connected to the piping of the upper gas phase section in the main body tank 100 and the incidental device groups 201 to 206 that are connected to the piping inserted into the upper well-like structure 110A. The incidental equipment groups 221 and 222 leading to the pipes inserted into the lower well-like structure 110B were carried out. In addition, the structure of the incidental equipment groups 201 to 206, 211, 212, 221, 222 was changed according to the specific contents of the test.
[0191]
In addition, a fluid sample was collected at the sampling port 300 provided in the middle of the piping or on the back of the main body tank, and environmental analysis such as concentration analysis of pollutants and pH and pressure was performed, and operation management and effect determination were performed. As a result of detailed examination of various fluid control and pollutant treatment through these operations and analyses, we obtained new technical knowledge as a countermeasure against soil contamination. Details are described below.
[0192]
FIG. 13 is a front view schematically showing the entire configuration of the purification test apparatus used for verifying the installation effect of the crushed stone layer 102 by performing only fluid control without adding contaminants to the system. In this experiment, gas and liquid were collected from the upper well-like structure 110 </ b> A using the gas suction pump 203. The recovered liquid was recovered by the suction receiver 202 and discharged out of the system by the liquid discharge pump 204 in a timely manner. The recovered gas was discharged out of the system from the gas suction pump 203.
[0193]
On the other hand, the gas to be sucked was automatically supplied from the gas reservoir 212 in accordance with the negative pressure generated by the gas suction in the main body tank 100. As the gas supplied from the gas reservoir 212, 30% argon-containing nitrogen was used, and gas was supplied by this mixed gas in a timely manner according to the weight reduction. Similarly, liquid supply to the system was performed using the water level adjusting cylinder 200 and the water level adjusting tank 221.
[0194]
In the configuration and operating conditions of the purification test apparatus, the same conditions are set in the two tanks on the left and right, but in order to verify the installation effect of the crushed stone layer 102, fine sand 103 is used instead of the crushed stone layer 102 in the left tank. Filled and the only setting condition in 2 tanks was different. Under such conditions, after a certain period of operation, gas is sampled in the unsaturated zone from the sampling port 300 on the back of the main body tank 100, and the argon concentration in the sample is measured. The influence range of the suction and the suction through the crushed stone layer 102 which is the wide fluid path layer 1 of the present invention was compared, and the installation effect was verified.
[0195]
FIG. 14 shows the distribution of the argon concentration in the gas sampled at each point of the sampling port 300 after 6 hours from the start of suction (the argon concentration in the intake gas at this time is 29%) as a result of the experiment. It is shown as a diagram. In the figure, the argon concentration distribution in the right tank shows a value of about 30%, which is almost the same as the concentration in the aerated gas, whereas the distribution in the left tank is a strainer of the upper well-like structure 110A for intake. Only the vicinity of the portion 111 is a high value, and the argon concentration tends to decrease as the distance from the strainer portion 111 increases.
[0196]
From this result, it was confirmed that the intake range through the crushed stone layer 102 can be set to a wider and uniform range of influence due to the suction than when a conventional intake well is used. In comparison of the amount of sucked water after 6 hours, the amount of water in the right tank is overwhelmingly large, and fluid control of liquid such as recovery and injection through the crushed stone layer 102 is easier than that of fine sand. It has been suggested.
[0197]
Subsequently, the volatile organic pollutant treatment with gas suction in the unsaturated zone above the crushed stone layer 102 was studied. Here, gasoline was evaluated as a pollutant. This evaluation was initially conducted using this purification test equipment, but since reproducibility was not obtained in the initial concentration settings of the left and right tanks, the evaluation system was changed to a small-scale column test. It has been implemented.
[0198]
The reason why the reproducibility could not be obtained is that the gasoline component was volatilized at the time of creating the simulated contaminated soil. In order to suppress this volatilization, after adding 1% by weight of gasoline to the target soil, Each sample simulated contaminated soil was prepared using a material that had been thoroughly mixed with freezing and pulverization using liquid nitrogen.
[0199]
FIG. 15 is a schematic diagram showing the overall configuration of the column test apparatus. The column 400 was made of cylindrical glass and had an inner diameter of 5 cm and a length of 50 cm, and the inner contact portion of both end lids was made of Teflon (registered trademark) or stainless steel. One end of the column 400 was connected to the gas reservoir 212, and gas was supplied as necessary. A gas suction pump 203 and an integrated gas flow meter 214 were connected to the other end, and gas was sucked under a certain condition.
[0200]
Further, the experimental systems were distinguished as (A), (B), and (C), respectively, depending on the type of soil packed in the column 400 and the difference in the intake method. There are three types of test soils used this time. In (A) and (C), each column 400 is filled with simulated contaminated soil mainly composed of fine sand 401 and medium sand 402. Two columns 400 were filled with mixed soil 403 in which fine sand and medium sand were further uniformly mixed. Also, as an intake method, pipes were connected before intake in (A) and (B) and intake was performed by the same gas suction pump 203, whereas in (C), the gas suction pump 203 was placed in each column 400. Were connected separately to perform suction.
[0201]
In the experimental system, the pollution suction technique for the geological formation as a prior art was compared with the technique for performing the pollution suction after the formation of the formation was destroyed, and each pollution treatment performance was evaluated. That is, in the experiment, the gas suction speeds in the experimental systems (A), (B), and (C) were made equal, and the treatment performance was compared with the residual oil concentration after inhaling for a fixed time.
[0202]
As a result of the experiment, the average concentrations of residual oil in the soil in each experimental system (A) and (B) after 14 days from the start of suction were (A): 0.357% and (B): 0, respectively. The treatment performance of the experimental system of (B), which is the soil with destroyed layer, was 0.12%. However, of the two columns 400 in the experimental system of (A), the average concentration in the column 400 filled with the medium sand 402 is 0.005%, and the performance exceeding the average concentration in the whole experimental system of (B) is It was seen. On the other hand, the average concentration in the column 400 packed with fine sand 401 was 0.709%.
[0203]
From these results, it was found that when the soil composition was simplified by the formation destruction, more effective suction treatment was possible than for the formation with a stratified structure. Furthermore, in the stratum having a stratified structure, the inhalation gas tends to pass through the stratum having higher air permeability, and this experiment suggests that the processing may be uneven.
[0204]
Subsequently, based on the experimental results, the processing performance of each experimental system (B) and (C) was compared. The experimental system of (C) has the same soil filling components as the experimental system of (A), but the suction method is different. This is because the suction flow for one of the columns 400 was set to be equal as an experimental condition to prevent the single flow of suction gas from occurring in the experimental system (A) in the previous experiment. by. The other basic conditions were the same as in the previous experiment.
[0205]
As a result, the average concentration of residual oil in the soil in each experimental system (B) and (C) after 14 days from the start of suction was (B): 0.009% and (C): 0.015, respectively. No significant difference was seen in the contamination treatment between the two experimental systems, and good treatment performance was seen in both systems. With this experiment, it is possible that the method of suctioning each stratum with a stratified structure and the method that simplifies the soil composition by the destruction of the stratum can exhibit almost the same treatment performance. It has been shown.
[0206]
FIG. 16 shows an outline of a medium-scale purification test apparatus when an evaluation relating to the suction method using the convex auxiliary structure 104 is performed. The upper surface of the crushed stone layer 102 in the left tank is covered with a stainless steel mesh, and five stainless mesh cylinders (diameter 5 cm, height 15 cm) filled with crushed stone having a particle diameter of 4 to 20 mm equivalent to the crushed stone layer are equally provided. Arranged. This corresponds to the convex auxiliary structure 104.
[0207]
Moreover, 1% of kerosene was added to the fine sand at a mixing weight ratio, and then the mixture was sufficiently stirred and mixed to make the test soil 105, and the left tank and the right tank were filled with the same weight. Intake was carried out by one gas suction pump 203 by collecting the pipes connected to the left and right tanks on the way. On the other hand, the sucked gas was automatically supplied from the gas reservoir 212. As the gas in the gas reservoir 212 of the left tank, 30% argon-containing nitrogen was used, and as the gas in the gas reservoir 212 of the right tank, pure nitrogen was supplied in a timely manner according to the amount of reduction.
[0208]
In the experimental system, the suction method using the convex auxiliary structure 104 and the crushed stone layer 102 in combination with the suction method using only the crushed stone layer 102 was compared, and the respective pollution treatment performances were evaluated. That is, the treatment performance was compared between the concentration of argon gas in the suction gas after inhalation for a certain time and the concentration of residual oil in the test soil.
[0209]
As a result, the average argon gas concentration in the aspirated gas in the total 5 days from the 23rd to 27th days after the start of the aspiration was 22.6%. The average residual oil concentration in the soil after 28 days was 0.12% for the left tank and 0.56% for the right tank, respectively. By this experiment, possibility that a more effective suction process could be achieved by combining the convex auxiliary structure 104 with the crushed stone layer 102 was shown.
[0210]
Further, from the result of the average argon gas concentration, it was estimated that the suction amount was different between the left tank and the right tank. In practical use of the convex auxiliary structure 104, the auxiliary structure 104 is concentrated in a portion with a high contamination concentration according to the concentration, and conversely, suction is performed only with the crushed stone layer 102 in a portion where the contamination is light. In the pollution control area, this experiment shows that the operation with partial adjustment of the suction amount according to the pollution concentration is effective when soils with different pollution concentrations are targeted.
[0211]
By the suction test, the influence of the suction amount on the treatment was observed. As a result of detailed evaluation of the influence of other elements on the suction treatment in a separate column test, the contamination was separately diluted with soil. It was found that the suction treatment effect can be enhanced.
[0212]
FIG. 17 is a schematic diagram showing the overall configuration of the column test apparatus. The basic configuration of this apparatus is the same as that of the column test apparatus shown in FIG. 15 described above. One end of the column 400 is connected to the gas reservoir 212 and gas is supplied as necessary, while the other end is connected to the other end. Connected the gas suction pump 203 and the integrated gas flow meter 214 to perform gas suction under a certain condition.
[0213]
As the soil to be filled in the column 400, a 3% kerosene-added soil 404 in which kerosene is added to fine sand at a mixing weight ratio of 3% and a 1% kerosene-added soil 405 in which 1% is added are prepared and sufficiently mixed with stirring. The soil was used as the test soil. Thereafter, a test soil layer of 20 cm sandwiched between No. 3 cinnabar sand layers was created in the column 400 and used as a test column. For each test system, (A) only one column 400 containing 3% kerosene-containing soil 404 and (B) three columns 400 containing 1% kerosene-containing soil 405 were connected in series. The system set the same suction volume and inhaled. Air was used as the supply gas.
[0214]
In the experimental system, the contamination treatment performance by dilution was evaluated. That is, the processing performance was compared based on the residual oil concentration after intake for a certain time. As a result, the average residual oil concentration in the soil in each experimental system after 20 days from the start of suction was (A): 0.875% and (B): 0.526%, respectively. Factors that cause this difference include the fact that the layer thickness of the adhering contaminated oil has decreased due to dilution, the difference in suction pressure, and the promotion of degradation due to the reduction in toxicity to decomposing microorganisms due to dilution. Although the degree of contribution of each of these factors could not be determined, this experiment revealed that more effective contamination repair can be achieved by a combination of this dilution operation and suction.
[0215]
FIG. 18 shows an outline of a medium-scale purification test apparatus used when studying the application of the convex auxiliary structure 104 and the crushed stone layer 102 to the microbial decomposition treatment of oil. The basic configuration of this apparatus is the same as that of the left tank used in the apparatus shown in FIG. 16 described above, except that a carbon dioxide absorption tank 215 and a pressure adjustment tank 216 are added to the circulation path of the intake gas, and oxygen in the system is The difference is that oxygen is used as the gas in the gas reservoir 212 to supplement the consumption, and that a nutrient solution tank 217 and a nutrient pump 218 are added for fertilizer addition in the middle of the supply pipe of the left tank. Thus, in the left tank, an experimental system that promotes the growth of aerobic microorganisms that assimilate oil was set up, and in the right tank, a control experimental system that suppressed the growth of microorganisms without adding oxygen and fertilizer was set up.
[0216]
In the experimental system, the application of the suction technique using the convex auxiliary structure 104 and the crushed stone layer 102 to the microbial decomposition treatment of oil was evaluated. That is, the amount of oxygen supplied to the gas reservoir 212 and the residual oil concentration in the test soil after a certain period of time were measured, and the applicability was evaluated.
[0217]
As a result, the test was stopped 124 days after the start of suction when the supply of oxygen was stopped, and the residual oil concentration in the sample soil was measured. The left tank: 0.01% or less, the right tank: 0.93% Met. The total amount of oxygen consumed in the left tank for 124 days was 1623L. Separately, when the number of general bacteria in the soil was measured, the left tank: 3 × 10 8 CFU / g soil, right tank: 2 × 10 7 CFU / g soil.
[0218]
From these results, it is surmised that the oil accumulation by the aerobic microorganisms was achieved in the left tank, and the suction method using the convex auxiliary structure 104 and the crushed stone layer 102 can be applied to the microbial treatment of the oil contamination. Sex was suggested. In the tests so far, the evaluation of the unsaturated zone contamination treatment was performed, and it was confirmed that the suction using the crushed stone layer 102 was effective for the unsaturated zone contamination treatment. Next, the saturation zone contamination using this crushed stone layer 102 was evaluated. Details will be described below.
[0219]
FIG. 19 shows an outline of a purification test apparatus used for evaluating a method for collecting a light non-aqueous contamination reservoir using a crushed stone layer. This is an attempt to collect a light non-aqueous contamination reservoir through the lower part of the crushed stone layer 102 by pumping water from the upper well-like structure 110A after the light non-aqueous contamination reservoir is drawn out from the formation by suction at the upper part of the crushed stone layer 102.
[0220]
In this evaluation, the gas was sucked through the gas suction pump 203 using the double pipe 203a. The light non-aqueous contamination reservoir and water were collected using a gas suction pump 203. On the other hand, the supply air was opened to the atmosphere through a pipe 219 communicating with the gas phase part at the upper part of the apparatus, and water was supplied using a water level adjusting cylinder 200 and a water level adjusting tank 221 so as to reach a constant water level.
[0221]
Moreover, the fluid in the apparatus is sucked through the sampling port 301 on the back of the apparatus, and kerosene that automatically accumulates light non-aqueous contamination is collected according to the negative pressure situation around the sampling port 301 resulting from the suction. Was connected to a sampling port 301 and a syringe 302 filled with kerosene.
[0222]
Based on these specifications, the left tank was filled with a crushed stone layer 102 and a fine sand layer 103 via a stainless steel mesh, and the middle and upper parts were filled with a fine sand layer 103 only. Intake was performed in both tanks under the same conditions, and pumping was performed at the same position on both the left and right sides by the strainer portion 111 of the upper well-like structure 110A, and pumping according to the recovery was performed.
[0223]
Using this apparatus, the total liquid recovery amount and the light non-aqueous contamination reservoir recovery amount are measured, and the light non-aqueous contamination reservoir recovery is performed in the right tank as a conventional technique and the left tank as a method using the crushed stone layer 102. A comparative evaluation was conducted.
From the second day when the fluid recovery was stabilized, the evaluation was performed with an average value for five days. The total amount of liquid recovered in the left tank was 63.4 L / day and the amount of light non-aqueous contamination reservoir was 523 ml / day, whereas the total liquid recovery amount in the right tank was 12.5 L / day. The recovery amount of the aqueous contamination reservoir was 52 ml / day.
[0224]
From the results described above, the ratio of the total liquid recovery amount and the light non-aqueous contamination pool recovery amount is 1: 0.008 for the left tank and 1: 0.004 for the right tank, and the conventional method using the crushed stone layer 102 is used. It was found that it can be recovered with nearly twice the efficiency of the technology. Moreover, in the simple recovery amount ratio, a recovery amount about 10 times that of the conventional technique was obtained. From these, the result of simply increasing the groundwater recovery efficiency not only increased the amount of collected light non-aqueous contamination reservoir, but also other factors, that is, gas suction from the upper surface of the crushed stone layer 102 clarified the light non-aqueous contamination reservoir. It was suggested that it was exuded to 102 and contributed to recovery.
[0225]
In this case, after the 7th day of the experiment, the liquid was collected only once a day and the experiment was continued. As a result, the average amount of light non-aqueous contaminants collected remained at 438 ml / day. It was shown that the contribution of is extremely high.
In general, it has been clarified that the light non-aqueous contamination reservoir recovery process through the crushed stone layer 102 that simultaneously performs the gas suction and the liquid suction can achieve a recovery that is more efficient than the prior art.
[0226]
Subsequently, the in-situ treatment in an oxidizing atmosphere using a crushed stone layer of light non-aqueous contaminants dissolved in water was evaluated. FIG. 20 shows an outline of the purification test apparatus used in this evaluation. Using this device, it is an attempt to circulate polluted water containing light non-aqueous pollutants under the ground using the crushed stone layer 102 and the upper and lower well-like structures 110A and 110B, and to repair the pollution without pumping water. .
[0227]
In this experiment, for the convenience of setting the equipment, the contaminated water is temporarily replaced by a method of reinjecting the system once it is out of the system. However, in actual operation, the upper and lower well-like structures 110A and 110B are used. An experimental system was constructed assuming a circulation system in which contaminated water does not move out of the system by a pipe connecting the two and a submersible pump installed in the upper well-like structure 110A.
[0228]
In this evaluation, the contaminated water was collected from the upper well-like structure 110A by the circulation pump 231 and then returned to the system from the lower well-like structure 110B through the pipe, and the circulation system was constructed by repeating this. Further, two pipes are branched in the middle of the pipe connecting the lower well-like structure 110 </ b> B and the circulation pump 231, and a nutrient solution supply pipe connected to the nutrient solution tank 217 and the nutrient solution pump 218 is connected to the upstream portion thereof. In the downstream portion, a constant flow rate discharging device 223 for discharging the circulating water out of the system by a certain amount was installed.
[0229]
In order to supply contaminated water corresponding to the discharge amount from the constant flow discharge device 223, supply of contaminated water using the water level adjusting cylinder 200 and the water level adjusting tank 221 was performed. The contaminated water used here was pentane dissolved in water by forced stirring. Further, oxygen was supplied to the circulating water through the Teflon bag tube 224 in the middle of the piping used for the circulation. Based on these apparatus configurations, an experiment was conducted by installing a crushed stone layer 102 in the middle left tank and a fine sand layer 103 imitating a natural layer in the middle right tank. In addition, when installing the crushed stone layer 102 in the middle of the left tank, an impermeable portion was installed on a part of the bottom surface.
[0230]
Using this apparatus, the comparative evaluation of the right tank, which is a conventional technique, and the left tank, which is a method using the crushed stone layer 102, was performed with respect to the contamination removal performance at the time of stable treatment. As a result, stable fluid operation was impossible in both the left and right tanks. That is, after 10 days from the start of operation, the injection gradually became difficult. Thereafter, the injection was impossible on the 16th day for the left tank and the 19th day for the right tank, and the experiment was stopped.
[0231]
As a result of investigating the cause of this phenomenon, we have concluded that the injection surface is blocked by the grown microorganisms. That is, it is because the microbial condensate cannot pass through the inner sand layer of the injection surface and the injection surface is blocked. Based on this result, it was decided to carry out the experiment again in order to avoid the operation trouble due to the blockage by using the crushed stone layer 102 as the site for the growth of microorganisms.
[0232]
In the experiment, oxygen supply and nutrient solution supply were performed as an operation for promoting the growth of microorganisms, but this supply system was transferred to the crushed stone layer 102 and the experiment was performed with a setting in which clogging hardly occurs. The outline is shown in FIG. Inhalation was performed using the gas suction pump 203, and a part thereof was again diffused through the vent pipe 203b installed under the crushed stone layer 102, thereby constructing a gas circulation system.
[0233]
In addition, in order to replenish the gas corresponding to the amount of discharge that is not circulated, the vent pipe 219 communicating with the gas phase part at the top of the main body tank 100 was opened to the atmosphere to supplement the gas supply. Further, in order to promote microbial decomposition through the vent pipe 203b, the nutrient solution was supplied from the nutrient solution tank 217 through the nutrient solution pump 218.
[0234]
In order to cope with another blockage, a line filter 226 having a pore diameter of 0.01 mm was incorporated in the middle of the pipe connecting the lower well-like structure 110B and the liquid discharge pump 225 in the experimental system. Further, the pipe was branched and a liquid discharge pump 225 was installed, and backwashing was performed by reversing the liquid feeding direction at regular intervals. In addition, ozone gas was added to the aeration gas at regular intervals from the vent pipe 203b to control the amount of microorganisms for sterilization and decomposition of surplus microorganisms.
[0235]
As a result, in the above-described experiment, the well blockage was observed within 20 days after the start of the experiment, but in this experiment, no operation failure due to the blockage was observed even after 106 days. Regarding the treatment of the pollutant, after the treatment was stabilized, the contaminated water supplied at about 90 mg / L as the oil concentration of the simulated contaminated water was decomposed until it was not detected in the discharged water. From this evaluation, it is clear that by controlling the growth of aerobic microorganisms that degrade pollutants in the crushed stone layer 102, it is possible to efficiently process in situ the light non-aqueous pollutants dissolved in water. It became.
[0236]
Further, when the applicability of the present method to other pollutants was examined using the above-described cleaning test apparatus, other petroleum hydrocarbons could be treated in the same operation. On the other hand, it was found that organic chlorine compounds, which are heavy non-aqueous pollutants, are suitable for a method of shifting to a circulating gas and treating them on the ground, rather than microbial decomposition. In addition, regarding nitrate nitrogen, it was confirmed that ozone addition was counterproductive, and that good treatment could be achieved by implementing countermeasures against clogging only by other backwashing and filter treatment.
[0237]
Subsequently, the in-situ treatment using the crushed stone layer of the heavy non-aqueous contamination reservoir in the saturated zone base was evaluated. In the heavy non-aqueous contamination reservoir treatment, the groundwater in the saturated zone was pumped and the formation gap was replaced with the atmosphere, and then the heat suction treatment method using the crushed stone layer and the convex auxiliary structure was evaluated.
[0238]
FIG. 22 is a schematic diagram of the cleaning test apparatus used for the heat suction treatment evaluation. Suction was performed by the gas suction pump 203 through the upper well-like structure 110 </ b> A through the crushed stone layer 102 and the convex auxiliary structure 104. Further, in order to use the reaction heat between the hydrogen peroxide solution and the soil as a heating source, heat is supplied from the chemical solution injection pump 241 and the chemical solution bottle 242 through the heating pipe 243 to the base of the simulated saturation zone through the lower well-like structure 110B. Hydrogen peroxide water was injected.
[0239]
The base of the simulated saturated zone was filled with silt soil, and depressions (diameter 3 cm, depth 3 cm) were formed on the upper surface at intervals of about 5 cm, and a portion in which heavy non-aqueous contamination pools accumulated was created. The upper part was filled with a medium sand layer, a crushed stone layer, and a fine sand layer and used for the test. Immediately before the start of the test, 50 ml of the trichlorethylene stock solution 99 was injected from the sampling port 300 on the back surface of the main body tank 100 immediately above the base of the simulated saturated zone to form a heavy non-aqueous contamination reservoir on the upper surface of the simulated saturated zone. . The re-addition of the hydrogen peroxide solution was performed several times when the temperature of the reaction part returned to the injected hydrogen peroxide solution temperature.
[0240]
As a result, when the temperature of the injected hydrogen peroxide solution was about 70 degrees, the maximum temperature at the base of the saturated zone after the addition was 93 degrees. After that, it took about 5 hours to decrease to 70 degrees. This reaction was repeated 5 times to complete the treatment, and as a result of measuring the concentration of trichlorethylene contained in the liquid remaining in the system, the silt soil, and the sand, the total remaining amount was determined. As a result, 0.35 g remaining was confirmed. It was. The initial charge of 50 ml corresponds to about 73 g, and as a result, it was confirmed that the heavy non-aqueous contamination reservoir with 99.5% or more of trichlorethylene was treated by this treatment.
[0241]
In the example described above, hydrogen peroxide was used, but the use of a heated solution containing a perinorganic acid such as permanganic acid or persulfuric acid or a perorganic acid such as peracetic acid was examined as another peroxide. As compared with hydrogen peroxide, the vaporizing action of pollutants was small, and effective treatment could not be achieved. In an additional study, these operations are performed mainly with hydrogen peroxide, such as direct decomposition of pollutants, soil clogging with residual components, and recovery and washing of residual components after reaction. Compared to the complicated operation, it was confirmed that there was difficulty in application.
[0242]
In general, it has been shown that the heat suction treatment using warm hydrogen peroxide water is effective for heavy non-aqueous contamination reservoir treatment. Further, it is considered that the hot hydrogen peroxide solution injected at the time of practical use expands concentrically around the injection point, and the treatment site is expected to expand like a pseudo-circular surface along with it. In order to collect the vaporized trichlorethylene generated by this treatment, it was suggested that the combined use of the crushed stone layer 102 capable of targeting a wide area and gas suction through the convex auxiliary structure 104 is desirable.
[0243]
Subsequently, the in-situ treatment using groundwater circulation under a reducing atmosphere using the crushed stone layer 102 was evaluated. Since the installation surface of the crushed stone layer 102 is installed across the saturated zone and the unsaturated zone, molecular oxygen is present in the upper gap, which becomes an obstacle when a reducing atmosphere is set to implement groundwater circulation. In order to overcome this obstacle, a method for maintaining a reducing atmosphere in the circulating water by installing a layer containing reduced iron in a part of the crushed stone layer 102 under the groundwater surface was examined. Further investigations were made on the degradation of pollutants under these conditions.
[0244]
FIG. 23 is a schematic diagram of a purification and cleaning apparatus that has performed groundwater circulation evaluation under a reducing atmosphere. In this experiment, the clay layer 106 was installed so as to divide the crushed stone layer 102 into two, and the upper layer of the crushed stone layer 102 was used as an activation reaction layer for reducing groundwater and promoting the growth of microorganisms. The mixed ground layer was prepared by mixing contaminated ground water from the aquifer and the above-described activated ground water to perform the pollution treatment.
[0245]
Furthermore, a curved path 107 was installed with clay in the main body tank 100 to promote mixing of both groundwaters. A groundwater circulation system was constructed to connect these layers. That is, a well-like structure 120 having three strainers on the upper and lower sides is installed in each layer, groundwater is collected from the central strainer 121c by the circulation pump 122, and the system is again connected to the upper and lower strainers 121a and 121b. A circulatory system that allows water to flow inside was constructed.
[0246]
Such a reduction reaction unit 108 was installed in the left tank, while the right tank was filled with crushed stone without using reduced iron powder, and used as a control for this experiment. After filling with soil, both tanks were boiled once and filled with deaerated water that was allowed to cool by standing, and then circulation was started. The dissolved oxygen concentration in the circulating water was measured every day and evaluated by comparing the two.
[0247]
As a result, the dissolved oxygen concentration at the beginning of the circulation was 0.01 mg / L or less. However, the dissolved oxygen concentration in the right tank increased to 1.53 mg / L after 1 day, and the number of days passed thereafter. An increase was observed, reaching 5.86 mg / L after 6 days. On the other hand, the dissolved oxygen concentration in the circulating water of the left layer was always stable at 0.01 mg / L or less.
[0248]
When 6 days passed, the redox potential of the circulating water in the left layer was measured and confirmed to be in a reducing atmosphere of -256 mV. By this experiment, it was found that a reducing atmosphere can be maintained in the groundwater circulation system using the crushed stone layer 102 by installing a layer containing reduced iron in a part of the crushed stone layer 102 under the groundwater surface.
[0249]
Subsequently, a treatment test for contaminated water was performed. The outline is shown in FIG. In this apparatus, in order to grow microorganisms in the activation reaction layer, a nutrient solution supply pipe connected to the nutrient solution tank 217 and the nutrient solution pump 218 is connected in the middle of the pipeline connecting the circulation pump 231. Then, ethanol was supplied into the system. As a countermeasure against the well blockage accompanying the growth of microorganisms, a line filter 226 having a pore diameter of 0.01 mm was incorporated in the middle of a pipe connected to the circulation pump 231.
[0250]
In addition, a pipe leading to the filtration surface of the line filter 226 and a liquid discharge pump 225 were installed, and the filtration residue was collected according to the blockage, and the filtration surface was washed. Contamination treatment is performed by mixing tetrachloroethylene 1 mg / L, nitrate ions 100 mg / L, and benzene 0.1 mg / L as decontaminated water with degassed water to create composite contaminated water, which is gently injected from the bottom of the main body tank 100. Then, water was poured to the upper part of the crushed stone layer 102 and used for the experiment.
[0251]
As a result, no significant decomposition was observed until 2 weeks after the start, but after that, the decomposition progressed, and at the point of 5 weeks after the start, each pollutant concentration in the circulating water was below the environmental standard value or detected, respectively. It was below the limit. During this period, no blockage by the grown microorganisms was observed, and the line filter 226 was not cleaned. From this test, it was found that the system can be decomposed for many types of contamination.
[0252]
Subsequently, the specifications of this system were partially changed, and the continuous treatment of contaminated groundwater was evaluated. The outline is shown in FIG. That is, in the middle of the pipe connecting the circulation pump 231, a constant flow discharge device 223 for discharging the circulating water out of the system by a fixed amount is installed, and a water level adjusting cylinder is provided to supply the contaminated water corresponding to the discharge. 200 and contaminated water was supplied using the water level adjustment tank 221. As the contaminated water, the composite contaminated water used in the above-described experiment was used for this experiment as it was. In addition, an aerobic aeration tank 250 for releasing the amount of anaerobic bacteria in the discharged water was installed, and a process for promoting the predation of bacteria by protozoa was performed.
[0253]
As a result, a decrease in circulating water contamination concentration was observed immediately after the start, and after 5 weeks, each contamination concentration was 0.005 mg / L or less of tetrachloroethylene, 1 mg / L or less of nitrate ion, 0.007 mg / L of benzene, respectively. It was stable near L, and all were able to meet the environmental standards. In addition, the total number of bacteria in the discharged water at this point is 6 × 10 7 CFU / ml, but 3 × 10 after passing through aerobic aeration tank 4 CFU / ml was observed, and the number of bacteria was reduced by 3 orders. Since the load on the two circulation pumps 231 increased due to the blockage from the 4th week, the circulation was reversed once a day, and the circulating water was passed through the line filter to perform backwashing. It has become possible.
[0254]
From this experiment, it was shown by this experiment that groundwater circulation in-situ treatment using a crushed stone layer 102 under a reducing atmosphere is effective for various pollutants and that groundwater treatment satisfying environmental standards is possible.
[0255]
As described in the above embodiments, regarding the soil contamination countermeasure method and the soil contamination countermeasure system according to the present invention, the contamination of the fluid in the processing system subject to the fluid control, the environmental analysis, etc. are performed, and the contamination It is also important to implement pollution measures according to the degree and environmental conditions.
[0256]
【The invention's effect】
According to the soil pollution countermeasure method and the soil pollution countermeasure system according to the present invention, fluid is injected and / or fluid is passed through a wide fluid path layer installed along the boundary between the underground saturated zone and unsaturated zone. Fluid control by recovery can be performed without providing a large number of wells in a wider area below the ground, and pollutants can be efficiently removed from a wide range of soil and groundwater without incurring a significant cost increase. Become.
[0257]
In addition, the fluid control through the wide-area fluid path layer can prevent the contaminants existing deeper than the wide-area fluid path layer from diffusing into the soil shallower than the wide-area fluid path layer. It is possible to prevent the pollutants existing in the soil from diffusing into the soil deeper than the wide fluid path layer. In addition, the above-described prevention of contamination diffusion can be further enhanced by various fluid flow operations through the wide-area fluid path layer.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view schematically showing a soil contamination countermeasure system for implementing a soil contamination countermeasure method according to a first embodiment of the present invention.
FIG. 2 is a perspective view schematically showing a wide-area fluid path layer according to various embodiments of the present invention.
FIG. 3 is a longitudinal sectional view for explaining fluid control in the soil contamination countermeasure system for implementing the soil contamination countermeasure method according to the first embodiment of the present invention.
FIG. 4 is a longitudinal sectional view schematically showing a soil contamination countermeasure method and a soil contamination countermeasure system according to a second embodiment of the present invention.
FIG. 5 is a longitudinal sectional view schematically showing a soil contamination countermeasure method and a soil contamination countermeasure system according to a third embodiment of the present invention.
FIG. 6 is a longitudinal sectional view schematically showing a soil contamination countermeasure method and a soil contamination countermeasure system according to a fourth embodiment of the present invention.
FIG. 7 is a longitudinal sectional view schematically showing a soil contamination countermeasure method and a soil contamination countermeasure system according to a fifth embodiment of the present invention.
FIG. 8 is a longitudinal sectional view schematically showing a soil contamination countermeasure method and a soil contamination countermeasure system according to a sixth embodiment of the present invention.
FIG. 9 is a longitudinal sectional view schematically showing a soil contamination countermeasure method and a soil contamination countermeasure system according to a seventh embodiment of the present invention.
FIG. 10 is a longitudinal sectional view schematically showing a soil contamination countermeasure method and a soil contamination countermeasure system according to an eighth embodiment of the present invention.
FIG. 11 is a cross-sectional view schematically showing a soil contamination countermeasure method and a soil contamination countermeasure system according to an eighth embodiment of the present invention.
FIG. 12 is a longitudinal sectional view schematically showing a purification test apparatus according to the first embodiment of the present invention.
FIG. 13 is a longitudinal sectional view schematically showing a purification test apparatus according to a second embodiment of the present invention.
FIG. 14 is an explanatory view schematically showing a test result by the purification test apparatus according to the second embodiment of the present invention.
FIG. 15 is an explanatory view schematically showing a column test apparatus according to a third embodiment of the present invention.
FIG. 16 is a longitudinal sectional view schematically showing a purification test apparatus according to a fourth embodiment of the present invention.
FIG. 17 is an explanatory diagram schematically showing a column test apparatus according to a fifth embodiment of the present invention.
FIG. 18 is a longitudinal sectional view schematically showing a purification test apparatus according to a sixth embodiment of the present invention.
FIG. 19 is a longitudinal sectional view schematically showing a purification test apparatus according to a seventh embodiment of the present invention.
FIG. 20 is a longitudinal sectional view schematically showing a purification test apparatus according to an eighth embodiment of the present invention.
FIG. 21 is a longitudinal sectional view schematically showing a purification test apparatus according to a ninth embodiment of the present invention.
FIG. 22 is a longitudinal sectional view schematically showing a purification test apparatus according to a tenth embodiment of the present invention.
FIG. 23 is a longitudinal sectional view schematically showing a purification test apparatus according to an eleventh embodiment of the present invention.
FIG. 24 is a longitudinal sectional view schematically showing a purification test apparatus according to a twelfth embodiment of the present invention.
FIG. 25 is a longitudinal sectional view schematically showing a purification test apparatus according to a thirteenth embodiment of the present invention.
[Explanation of symbols]
A ... Fluid flow
B ... Groundwater flow
C ... Groundwater flow
D ... Underground air flow
E ... Hot air
F ... Heat washing liquid
K ... Washing water
N1 ... Light non-aqueous liquid reservoir
N2 ... heavy non-aqueous liquid reservoir
R ... Impermeable layer
W ... Groundwater surface
1 ... Wide fluid path layer
2 ... saturation zone
3 ... unsaturated zone
4 ... Soil cover
5 ... Auxiliary structure
6 ... Natural strata classification
10 ... Well-like structure
11a ... Strainer section
11b ... Strainer section
11c ... Strainer section
12 ... Sealing
13 ... Packer
14 ... Suction tube
15 ... Injection tube
16 ... Diffuser
17 ... Air supply pipe
18 ... Heat supply pipe
19 ... Watering pipe
21 ... Vacuum pump
22 ... Liquid carry-out pump
23. Contamination processing equipment
24 ... Fluid receiving tank
30 ... Impermeable wall
31 ... Impermeable wall
32 ... Impermeable wall
32a ... Flange part
33 ... Reducing substance containing part
34 ... Open wall
35 ... Part containing particulate contamination
40 ... Submersible pump
40a ... Catchment part
41 ... Water supply pipe
42 ... Strainer
43 ... Filtrate collection tube
44 ... Recovery unit
50 ... Nutrient solution supply device
51 ... Nutrient solution supply tank
52. Adjustment processing unit
53 ... Diffuser

Claims (25)

土壌および地下水から汚染物質を除去して修復するための土壌汚染対策方法において、
地下の飽和帯と不飽和帯の境界部周辺に沿って、互いに連通する数多の間隙を含む広域流体路層を設置し、
前記広域流体路層を通じて、該広域流体路層の周囲への流体の注入、および該広域流体路層の周囲からの流体の回収のうち、少なくとも何れか一方による流体制御を行うことを特徴とする土壌汚染対策方法。In soil pollution control methods to remove and repair pollutants from soil and groundwater,
A wide-area fluid channel layer including many gaps communicating with each other is installed along the boundary between the underground saturated zone and unsaturated zone,
Fluid control is performed by at least one of injection of fluid around the wide area fluid path layer and recovery of fluid from the circumference of the wide area fluid path layer through the wide area fluid path layer. Soil pollution countermeasures. 前記広域流体路層を通じて、前記流体である気体と液体の回収を並行して行うことを特徴とする請求項１に記載の土壌汚染対策方法。The soil contamination countermeasure method according to claim 1, wherein the gas and liquid as the fluid are collected in parallel through the wide-area fluid path layer. 地層構造を有しない汚染土壌を前記広域流体路層上に積層させた後、前記広域流体路層を通じての流体制御により、前記汚染土壌中の汚染物質を除去することを特徴とする請求項１または２に記載の土壌汚染対策方法。The pollutant in the contaminated soil is removed by fluid control through the wide-area fluid path layer after laminating contaminated soil having no stratum structure on the wide-area fluid path layer. 2. The soil contamination countermeasure method according to 2. 汚染土壌を汚染濃度別に区域を指定して前記広域流体路層上に積層させた後、前記区域毎に汚染濃度に応じた前記広域流体路層を通じての流体制御により、前記汚染土壌中の汚染物質を除去することを特徴とする請求項１または２に記載の土壌汚染対策方法。After the contaminated soil is laminated on the wide-area fluid path layer by designating the area according to the pollution concentration, the pollutant in the contaminated soil is controlled by fluid control through the wide-area fluid path layer according to the pollution concentration for each area. The soil contamination countermeasure method according to claim 1 or 2, wherein the soil is removed. 汚染土壌を混合し汚染物質濃度を平均化する操作、または客土を混入し更に汚染物質濃度を低くして平均化する操作を行った後、前記広域流体路層を通じての流体制御により、前記汚染土壌中の汚染物質を除去することを特徴とする請求項１または２に記載の土壌汚染対策方法。After mixing the contaminated soil and averaging the pollutant concentration, or after mixing the soil and reducing the pollutant concentration and averaging, the contamination is controlled by fluid control through the wide fluid path layer. The soil contamination countermeasure method according to claim 1 or 2, wherein contaminants in the soil are removed. 前記広域流体路層の内部ないし周囲に難透過性壁を設置し、該難透過性壁により土壌間隙の連続性を一部遮断し流体流路を矯正することにより汚染除去を促すことを特徴とする請求項１，２，３，４または５に記載の土壌汚染対策方法。A hard-permeable wall is installed in or around the wide-area fluid path layer, and the soil-continuity of the soil gap is partially blocked by the hard-permeable wall and the fluid flow path is corrected to promote decontamination. The soil contamination countermeasure method according to claim 1, 2, 3, 4 or 5. 前記広域流体路層を通じての流体制御により、前記飽和帯に地下水循環系を形成することを特徴とする請求項１，２，３，４，５または６に記載の土壌汚染対策方法。The soil contamination countermeasure method according to claim 1, 2, 3, 4, 5 or 6, wherein a groundwater circulation system is formed in the saturation zone by fluid control through the wide-area fluid path layer. 地下水系を酸化雰囲気下に保つことを特徴とする請求項１，２，３，４，５，６または７に記載の土壌汚染対策方法。The soil contamination countermeasure method according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the groundwater system is maintained in an oxidizing atmosphere. 地下水系にて好気性微生物の好気的代謝を利用した水処理を併せて行うことを特徴とする請求項１，２，３，４，５，６，７または８に記載の土壌汚染対策方法。The soil contamination countermeasure method according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein water treatment using aerobic metabolism of aerobic microorganisms is also performed in a groundwater system. . 地下水系を還元雰囲気下に保つことを特徴とする請求項１，２，３，４，５，６または７に記載の土壌汚染対策方法。The soil contamination countermeasure method according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the groundwater system is maintained in a reducing atmosphere. 地下水系にて嫌気性微生物の嫌気的代謝を利用した水処理を併せて行うことを特徴とする請求項１，２，３，４，５，６，７，８または１０に記載の土壌汚染対策方法。The soil contamination countermeasure according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 10, wherein water treatment using anaerobic metabolism of anaerobic microorganisms is performed in a groundwater system. Method. 地下水の一部を、地上に設置した汚染処理装置を通じて浄化処理し、該汚染処理装置で処理した地下水を再び地下水系に戻すことにより、地下水を浄化することを特徴とする請求項１，２，３，４，５，６，７，８，９，１０または１１に記載の土壌汚染対策方法。The groundwater is purified by purifying a part of the groundwater through a pollution treatment device installed on the ground and returning the groundwater treated by the pollution treatment device to the groundwater system again. The soil contamination countermeasure method according to 3, 4, 5, 6, 7, 8, 9, 10 or 11. 地表部と前記飽和帯下部より液体を注入し、該液体を前記広域流体路層にて回収する流体流を形成することで、前記飽和帯および前記不飽和帯に存する汚染物質を除去することを特徴とする請求項１，２，３，４，５，６，７，８，９，１０，１１または１２に記載の土壌汚染対策方法。Injecting liquid from the ground surface and the lower part of the saturated zone, and forming a fluid flow for collecting the liquid in the wide-area fluid path layer, thereby removing contaminants existing in the saturated zone and the unsaturated zone. The soil contamination countermeasure method according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12. 地下水面下より散気を行い、前記広域流体路層を通じての吸気により、散気気体と共に汚染物質を回収することを特徴とする請求項１，２，３，４，５，６，７，８，９，１０，１１，１２または１３に記載の土壌汚染対策方法。Air is diffused from below the groundwater surface, and pollutants are collected together with the air diffused gas by intake through the wide fluid path layer. , 9, 10, 11, 12 or 13. 土壌中の汚染物質の気化を促す操作と共に、前記広域流体路層を通じての吸気により、気化した汚染物質を回収することを特徴とする請求項１，２，３，４，５，６，７，８，９，１０，１１，１２，１３または１４に記載の土壌汚染対策方法。The vaporized pollutant is recovered by suction through the wide-area fluid path layer together with an operation for promoting vaporization of the pollutant in the soil. The soil contamination countermeasure method according to 8, 9, 10, 11, 12, 13 or 14. 前記汚染物質の気化を促す操作が、加熱した過酸化物溶液を土壌中に注入することであることを特徴とする請求項１５に記載の土壌汚染対策方法。The soil contamination countermeasure method according to claim 15, wherein the operation for promoting vaporization of the contaminant is injecting a heated peroxide solution into the soil. 前記広域流体路層の上下面部の何れか少なくとも一方より略垂直方向に突出し、前記広域流体路層と同様に互いに連通する数多の間隙を含み、該広域流体路層に連通する凸様の補助構造物を形成し、
前記広域流体路層および前記補助構造物を通じて、該広域流体路層および該補助構造物の周囲に対する流体の注入、および該広域流体路層の周囲からの流体の回収のうち、少なくとも何れか一方による流体制御を実施することを特徴とする請求項１，２，３，４，５，６，７，８，９，１０，１１，１２，１３，１４，１５または１６に記載の土壌汚染対策方法。Convex-shaped auxiliary members that project in a substantially vertical direction from at least one of the upper and lower surface portions of the wide-area fluid path layer and include many gaps that communicate with each other in the same manner as the broad-area fluid path layer. Forming a structure,
According to at least one of injection of fluid to the periphery of the wide area fluid path layer and the auxiliary structure and recovery of fluid from the periphery of the wide area fluid path layer through the wide area fluid path layer and the auxiliary structure The soil contamination countermeasure method according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16, wherein fluid control is performed. . 前記広域流体路層の周囲を囲む遮水壁を地下に設置し、前記補助構造物を、前記広域流体路層の上面部周囲にて前記遮水壁の内側壁と一部または全面が接するように形成し、
前記遮水壁の外側周囲にて自然地下水位が最も高い地点にある遮水壁の一部を外側と連通可能に開放すること、または遮水壁内側に液体を注入することで、前記補助構造物内における地下水位を、前記遮水壁の外側周囲における自然地下水位の最高位と略同位かそれ以上の高位に保つことを特徴とする請求項１７に記載の土壌汚染対策方法。A water-impervious wall surrounding the periphery of the wide-area fluid path layer is installed in the basement, and the auxiliary structure is partially or entirely in contact with the inner wall of the water-impervious wall around the upper surface of the wide-area fluid path layer. Formed into
The auxiliary structure is formed by opening a part of the water shielding wall at a point where the natural groundwater level is highest around the outside of the water shielding wall so as to communicate with the outside, or injecting liquid into the water shielding wall. 18. The soil contamination countermeasure method according to claim 17, wherein the groundwater level in the object is maintained at a level substantially equal to or higher than the highest natural groundwater level around the outside of the impermeable wall. 前記広域流体路層を難透水ないし遮水施工で仕切ることで、地下で互いに連通可能に区画された複数の反応部を形成し、これらの各反応部に一連の流体流を通過せしめることにより、前記各反応部が連結して成る汚染処理系を構築することを特徴とする請求項１，２，３，４，５，６，７，８，９，１０，１１，１２，１３，１４，１５，１６，１７または１８に記載の土壌汚染対策方法。By partitioning the wide-area fluid path layer with impervious or impervious construction, forming a plurality of reaction sections partitioned to communicate with each other underground, and allowing each of these reaction sections to pass a series of fluid flows, A contamination treatment system in which the reaction parts are connected to each other is constructed, characterized in that a contamination treatment system is constructed. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 11, The soil contamination countermeasure method according to 15, 16, 17 or 18. 土壌および地下水から汚染物質を除去して修復するための土壌汚染対策システムにおいて、
地下の飽和帯と不飽和帯の境界部周辺に沿って設置され、互いに連通する数多の間隙を含む広域流体路層と、
地上より前記広域流体路層に連通可能に設置した井戸様構造体とを有し、
前記井戸様構造体により前記広域流体路層を通じて、該広域流体路層の周囲に対する流体の注入、および該広域流体路層の周囲からの流体の回収のうち、少なくとも何れか一方による流体制御を実施可能に構成したことを特徴とする土壌汚染対策システム。In a soil pollution control system for removing and repairing pollutants from soil and groundwater,
A wide-area fluid channel layer that is installed along the boundary between the underground saturated zone and unsaturated zone and includes a number of gaps communicating with each other;
A well-like structure installed to be able to communicate with the wide-area fluid path layer from the ground,
Fluid control by at least one of injection of fluid to the periphery of the wide area fluid path layer and recovery of fluid from the periphery of the wide area fluid path layer is performed by the well-like structure through the wide area fluid path layer. A soil pollution control system that is configured to be possible. 前記広域流体路層は、所定範囲で粒状物を密に集合させた状態に積層して成ることを特徴とする請求項２０に記載の土壌汚染対策システム。21. The soil pollution control system according to claim 20, wherein the wide-area fluid path layer is formed by laminating granular materials in a predetermined range in a dense range. 前記広域流体路層の上下面部の何れか少なくとも一方より略垂直方向に突出し、前記広域流体路層と同様に互いに連通する数多の間隙を含み、該広域流体路層に連通する凸様の補助構造物を形成したことを特徴とする請求項２０または２１に記載の土壌汚染対策システム。Convex-shaped auxiliary members that project in a substantially vertical direction from at least one of the upper and lower surface portions of the wide-area fluid path layer and include many gaps that communicate with each other in the same manner as the broad-area fluid path layer The soil contamination countermeasure system according to claim 20 or 21, wherein a structure is formed. 前記補助構造物は、汚染物質の吸着または分解を促進する材質を含むことを特徴とする請求項２２に記載の土壌汚染対策システム。23. The soil contamination countermeasure system according to claim 22, wherein the auxiliary structure includes a material that promotes adsorption or decomposition of contaminants. 前記井戸様構造体は、地中に連通するストレーナ部を軸方向に複数設けて成り、各ストレーナ部の少なくとも１つを、前記広域流体路層に連通する位置に配置させることを特徴とする請求項２０，２１，２２または２３に記載の土壌汚染対策システム。The well-like structure includes a plurality of strainer portions that communicate with the ground in the axial direction, and at least one of the strainer portions is disposed at a position that communicates with the wide-area fluid path layer. Item 24. The soil pollution control system according to Item 20, 21, 22, or 23. 前記井戸様構造体の内部に、一の前記ストレーナ部から集水された地下水を他の前記ストレーナ部より土壌中に注入するためのポンプを設け、
前記ポンプの集水部を、該集水部より集水される地下水を濾過するストレーナで覆い、
地上から通気可能な給気経路を前記井戸様構造体の内部に挿通し、該給気経路の下端出口を、前記集水部側より前記ストレーナ内側を臨む位置に配置させ、
地上まで連通する濾過物回収経路を前記井戸様構造体の内部に挿通し、該濾過物回収経路の下端に、前記ストレーナを囲む回収部を設け、
前記ポンプの稼動に伴い前記ストレーナ表面に蓄積した濾過物を、前記給気経路からの通気により剥離した際に、該剥離した濾過物を前記濾過物回収経路により通気気体と共に地上に回収することを特徴とする請求項２４に記載の土壌汚染対策システム。Provided inside the well-like structure is a pump for injecting groundwater collected from one strainer part into the soil from the other strainer part,
Cover the water collection part of the pump with a strainer that filters the groundwater collected from the water collection part,
An air supply path that can be ventilated from the ground is inserted into the well-like structure, and a lower end outlet of the air supply path is disposed at a position facing the inside of the strainer from the water collecting part side,
The filtrate collection path communicating to the ground is inserted into the well-like structure, and a collection section surrounding the strainer is provided at the lower end of the filtrate collection path,
When the filtrate accumulated on the strainer surface with the operation of the pump is separated by ventilation from the air supply path, the separated filtrate is collected on the ground together with the aeration gas by the filtrate collection path. 25. The soil contamination countermeasure system according to claim 24, wherein
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