JP4446247B2

JP4446247B2 - Purification method for contaminated soil containing hazardous substances

Info

Publication number: JP4446247B2
Application number: JP2004265467A
Authority: JP
Inventors: 芳雄飯塚; 渉相澤; 貞美芹澤
Original assignee: Shimizu Corp
Current assignee: Shimizu Corp
Priority date: 2004-09-13
Filing date: 2004-09-13
Publication date: 2010-04-07
Anticipated expiration: 2024-09-13
Also published as: JP2006075800A

Description

本発明は、有害物質を含有する汚染土壌の浄化方法に関するものであり、特に、ダイオキシン類、有機化合物、重金属等の有害物質を含有する汚染土壌から、有害物質を除去する汚染土壌の浄化方法に関するものである。 The present invention relates to a method for purifying contaminated soil containing hazardous substances, and more particularly to a method for purifying contaminated soil that removes harmful substances from contaminated soil containing harmful substances such as dioxins, organic compounds, and heavy metals. Is.

ダイオキシン類は有害物として知られ、極めて微量であっても環境に流出すると、この汚染環境を介して人体に取り込まれ、人体の健康に悪い影響を及ぼすものであり、その浄化対策あるいは封じ込め対策が緊急の課題となっている。このダイオキシン類は、水に溶けにくく、蒸発しにくい反面、脂肪等には溶けやすいという性質を持っている。また、他の化学物質や酸、アルカリにも簡単に反応せず、安定した状態を保つことが多い。 Dioxins are known as harmful substances, and even if they are in very small quantities, if they are released into the environment, they are taken into the human body through this polluted environment and have a negative effect on the health of the human body. It is an urgent issue. These dioxins have the property of being hardly soluble in water and difficult to evaporate, but easily dissolved in fat and the like. Moreover, it does not easily react with other chemical substances, acids, and alkalis, and often maintains a stable state.

このダイオキシン類の現在の主な発生源としては、ごみ焼却による燃焼がある。土壌への汚染原因としては、ごみ燃焼により大気中に放出されたダイオキシン類の地上への落下の他に、この焼却炉の解体時での流出が考えられる。また、農薬工場・農薬保管庫で使用された一部の農薬に不純物として含まれていたものが土壌へ混入する場合がある。また、かつて使用されていたＰＣＢ、特にコプラナーＰＣＢの環境中への流出・蓄積等の発生源がある。この土壌中に流出したダイオキシン類は、土壌中の微細粒子に付着していると考えられる。 The current main source of dioxins is combustion by refuse incineration. Possible causes of soil contamination include not only the fall of dioxins released into the atmosphere by garbage combustion onto the ground, but also the outflow of the incinerator when it is dismantled. In addition, some pesticides used in agricultural chemical factories and pesticide storage warehouses may contain impurities as impurities. In addition, there are sources of outflow / accumulation into the environment of PCBs that were once used, especially coplanar PCBs. Dioxins that have flowed into the soil are considered to be attached to fine particles in the soil.

従来からのダイオキシン類の浄化対策としては、（１）長期間に亘ってこの難分解性の有害物質を熱分解や化学的分解によって浄化する方法、（２）密閉空間内で加熱分離し、その後冷却により凝集回収する熱脱着法によって浄化する方法、が採られている。しかし、これらの浄化方法は処理費用が高価であり、このため浄化対象量が大量の場合には経済的に適用が困難であった。 Conventional purification measures for dioxins include (1) a method of purifying this indestructible harmful substance over a long period of time by thermal decomposition or chemical decomposition, (2) heat separation in an enclosed space, and then A method of purifying by a thermal desorption method of aggregating and recovering by cooling is employed. However, these purification methods have a high processing cost, and therefore are difficult to apply economically when the amount to be purified is large.

また、汚染土壌中に含まれるダイオキシン類については、その割合が比較的低濃度の場合には、（３）汚染土壌を遮水シート、遮水地中壁等によって遮水・遮断された空間内に封じ込める方法が知られている。しかし、この方法においては、ダイオキシン類は難分解性のため、半永久的に汚染物質が分解浄化されることなく大量の汚染物質を管理する必要がある。 In addition, for dioxins contained in contaminated soil, if the ratio is relatively low, (3) In a space where the contaminated soil is shielded or blocked by a water shielding sheet, the inner wall of the water shielding ground, etc. It is known how to contain it. However, in this method, since dioxins are hardly decomposable, it is necessary to control a large amount of pollutants without semi-permanently degrading and purifying the pollutants.

そこで、上記の方法に変えて、（４）汚染土壌を洗浄処理して減量化処分する方法が検討されている。このような浄化法として、特許文献１に挙げられる方法がある（特許文献１参照）。この浄化方法は、スラリー化した油脂性の有害物質を含有する汚染土壌に対し、当該有害物質を選択的に吸着する銅フタロシアニン系の多環芳香族吸着剤である吸着子を収容した透過性の収容具を混入・攪拌し、汚染土壌内に含有された有害物質を吸着子に吸着させ、しかる後、収納具を汚染浄化対象土壌から分離するものであり、油脂性の有害物質を含有する汚染土壌等を脱水減量化して浄化する方法（減量化処分方法）である。 Therefore, in place of the above method, (4) a method of washing and reducing the contaminated soil to reduce the amount of waste has been studied. As such a purification method, there is a method described in Patent Document 1 (see Patent Document 1). This purification method is a permeable material containing adsorbents, which are copper phthalocyanine-based polycyclic aromatic adsorbents that selectively adsorb the harmful substances to the contaminated soil containing the slurried oily harmful substances. Mixing and stirring the container, adsorb the harmful substances contained in the contaminated soil to the adsorbent, and then separate the container from the soil to be contaminated and contaminated, containing oily and harmful substances This is a method of dehydrating and purifying soil and the like (a method for reducing and disposing of soil).

一方、ダイオキシン類と並び有害物質として知られている重金属の一部も、一般に水に溶けにくく、かつ土壌に吸着されやすいものが多い。そのため、ダイオキシン類汚染土壌と重金属汚染土壌とは、類似した形態にあると言える。両者の大きく異なる点は、その環境基準値であり、例えば、カドミウムの土壌含有基準値は１５０ｍｇ／ｋｇ以下であるのに対し、ダイオキシン類の土壌環境基準値は１０００ｐｇ−ＴＥＱ／ｇ以下と非常に厳しい点である。
特開２００２−２３３８５９号公報 On the other hand, some of heavy metals known as harmful substances as well as dioxins are generally difficult to dissolve in water and easily adsorbed to soil. Therefore, it can be said that dioxin-contaminated soil and heavy metal-contaminated soil are in a similar form. The major difference between the two is the environmental standard value, for example, the soil content standard value of cadmium is 150 mg / kg or less, while the soil environmental standard value of dioxins is 1000 pg-TEQ / g or less. It is a tough point.
Japanese Patent Laid-Open No. 2002-233859

しかしながら、特許文献１に係る浄化方法にあっては、ダイオキシン類を吸着子に吸着させ濾過した後の濾過水については、ダイオキシン類濃度が低減しているため、再利用に供してはいるものの、処理土については、ダイオキシン濃度を測定していないため、どれだけ土が浄化されたかは不明であり、この処理土を吸着後の吸着子とともにダイオキシン封じ込め処理を行っていることから、処分費もそれ程低減したものではなかった。 However, in the purification method according to Patent Document 1, the dioxins are adsorbed on the adsorbent and filtered, and the dioxins concentration is reduced. Since the dioxin concentration was not measured for the treated soil, it is unclear how much the soil was purified, and because the treated soil is treated together with the adsorbent after adsorption, the disposal cost is also much higher. It was not reduced.

また、特許文献１に係る浄化方法にあっては、浄化対象の油脂性の有害物質は、ダイオキシン類に限られ、ダイオキシン類の他に重金属等が含まれるような複合汚染までをも対象とするものではなかった。 In addition, in the purification method according to Patent Document 1, the fat and oily harmful substances to be purified are limited to dioxins, and include even complex contamination that includes heavy metals and the like in addition to dioxins. It was not a thing.

本発明は、上記従来技術の問題点に鑑み、洗浄土砂の再利用を図り、安全で安価な浄化処理であって、複合汚染土壌に対しても適用可能である有害物質を含有する汚染土壌の浄化方法を提供することを目的とする。 In view of the above-described problems of the prior art, the present invention is a safe and inexpensive purification process for reusing washed soil, which is a contaminated soil containing harmful substances that can be applied to complex contaminated soil. An object is to provide a purification method.

かかる課題を解決するため、請求項１にかかる発明は、有害物質を含有する汚染土壌から有害物質を除去し、洗浄土砂と有害物質の濃縮した微細土粒子とに分離し、洗浄土砂を再生利用に供し、かつ有害物質の濃縮した微細土粒子を回収処理する汚染土壌の浄化方法であって、前記有害物質を含有する汚染土壌に水と添加剤を添加して混合し、スラリーとする工程（Ａ−１）と、該スラリーを濯いで、粒子径が７５μｍ以下の微細土粒子を含む懸濁水と、粒子径が７５μｍを超える土砂粒子とに分離する第１濯ぎ工程（Ａ−２）と、分離した前記土砂粒子の汚染レベルを判定する工程（Ａ−３）とを有し、該工程（Ａ−３）での判定により汚染レベルが基準値以下となったことを条件としてその土砂粒子を洗浄土砂として再生利用し、前記工程（Ａ−２）で分離した微細土粒子を含む懸濁水に、５０〜５０００ｐｐｍの凝集剤を添加して該懸濁水を凝集分離濃縮し、前記微細土粒子の集合体であるフロックと分離水とに分離する工程（Ｂ−１）と、該フロックを脱水処理し、微細土粒子と分離水とに分離する工程（Ｂ−２）とを経て、前記有害物質の濃縮した微細土粒子を得ることを特徴とする有害物質を含有する汚染土壌の浄化方法である。 In order to solve this problem, the invention according to claim 1 removes harmful substances from contaminated soil containing harmful substances, separates them into washed soil and fine soil particles enriched with harmful substances, and recycles the washed soil And a method for purifying contaminated soil, which collects fine soil particles enriched in harmful substances, and adds water and additives to the contaminated soil containing the harmful substances and mixes them to form a slurry ( A-1), and a first rinsing step (A-2) for rinsing the slurry to separate suspended water containing fine soil particles having a particle size of 75 μm or less and earth and sand particles having a particle size of more than 75 μm , A step (A-3) of determining the contamination level of the separated earth and sand particles , and the soil particles are determined on the condition that the contamination level is equal to or lower than a reference value by the determination in the step (A-3). and washed sand and recycled to the step The aqueous suspension containing the separated fine soil particles (A-2), the該懸turbid aggregate separation and concentration by adding a coagulant 50 to 5000 ppm, the flocs and separated water is an aggregate of the fine soil particles Through the step (B-1) of separating the flocs and the step (B-2) of separating the flocs into fine soil particles and separated water , to obtain fine soil particles concentrated with the harmful substances. It is the purification method of the contaminated soil containing the harmful substance characterized by this.

請求項２にかかる発明は、前記工程（Ａ−３）において、汚染レベルが基準値を超えるのであれば、この土砂粒子を擦りもみする工程（Ａ−４）と、この擦りもみ後の土砂粒子を濯いで、微細土粒子を含む懸濁水と土砂粒子とに分離する第２濯ぎ工程（Ａ−５）とを経て、分離した前記土砂粒子の汚染レベルを再度判定する工程（Ａ−６）とを有し、該工程（Ａ−６）での判定により汚染レベルが基準値以下となったことを条件としてその土砂粒子を洗浄土砂として再生利用し、前記工程（Ａ−５）で分離した微細土粒子を含む懸濁水を前記工程（Ａ−２）で分離した微細土粒子を含む懸濁水と共に凝集分離濃縮する請求項１に記載の有害物質を含有する汚染土壌の浄化方法である。 The invention according to claim 2 includes the step (A-4) of rubbing the earth and sand particles if the contamination level exceeds the reference value in the step (A-3), and the earth and sand particles after the rubbing. And a second rinsing step (A-5) for separating the suspended water containing fine soil particles and the sand particles, and a step of determining again the contamination level of the separated sand particles (A-6); Fine particles separated in the step (A-5) by recycling the earth and sand particles as washing earth and sand on the condition that the contamination level becomes a reference value or less by the judgment in the step (A-6). a method of purifying contaminated soil containing harmful substances as defined in claim 1 to agglomerate separated concentrate with an aqueous suspension containing fine soil particles suspended water separated in the step (a-2) containing the soil particles.

請求項３にかかる発明は、前記工程（Ａ−４）が、この土砂粒子に添加剤を添加して擦りもみする工程（Ａ−４’）と、この擦りもみ後の土砂粒子を吸着反応槽に送り、攪拌させる工程（Ａ−７）である請求項２に記載の有害物質を含有する汚染土壌の浄化方法である。 The invention according to claim 3, wherein the step (A-4) is a step of fir rubbed by adding an additive to the soil particles (A-4 '), adsorption reaction vessel sediment particles after the rubbing fir The method for purifying contaminated soil containing a hazardous substance according to claim 2, wherein the method is a step (A-7) of sending to the mixture and stirring.

請求項４にかかる発明は、有害物質を含有する汚染土壌から有害物質を除去し、洗浄土砂と有害物質の濃縮した微細土粒子とに分離し、洗浄土砂を再生利用に供し、かつ有害物質の濃縮した微細土粒子を回収処理する汚染土壌の浄化方法であって、前記有害物質を含有する汚染土壌に水と添加剤を添加して混合し、スラリーとする工程（Ａ−１）と、該スラリーを濯いで、粒子径が７５μｍ以下の微細土粒子を含む懸濁水と、粒子径が７５μｍを超える土砂粒子とに分離する第１濯ぎ工程（Ａ−２）と、分離した前記土砂粒子の汚染レベルを判定する工程（Ａ−３）と、該工程（Ａ−３）において、汚染レベルが基準値を超えるのであれば、この土砂粒子を選別して、異物を除去する工程（Ａ−８）と、この異物除去後の土砂粒子を擦りもみする工程（Ａ−４）と、この擦りもみ後の土砂粒子を濯いで、微細土粒子を含む懸濁水と土砂粒子とに分離する第２濯ぎ工程（Ａ−５）と、分離した前記土砂粒子の汚染レベルを再度判定する工程（Ａ−６）とを有し、該工程（Ａ−６）での判定により汚染レベルが基準値以下となったことを条件としてその土砂粒子を洗浄土砂として再生利用し、前記工程（Ａ−５）で分離した懸濁水と前記工程（Ａ−２）で分離した懸濁水に、５０〜５０００ｐｐｍの凝集剤を添加して該懸濁水を凝集分離濃縮し、前記微細土粒子の集合体であるフロックと分離水とに分離する工程（Ｂ−１）と、該フロックを脱水処理し、微細土粒子と分離水とに分離する工程（Ｂ−２）とを経て、前記有害物質の濃縮した微細土粒子を得ることを特徴とする有害物質を含有する汚染土壌の浄化方法である。 The invention according to claim 4 removes harmful substances from contaminated soil containing harmful substances, separates them into washed soil and fine soil particles enriched with harmful substances, recycles the washed soil and recycles harmful substances. A method for purifying contaminated soil that collects and concentrates fine soil particles, wherein water and additives are added to and mixed with the contaminated soil containing the harmful substances to form a slurry (A-1), A first rinsing step (A-2) in which the slurry is rinsed and separated into suspended water containing fine soil particles having a particle size of 75 μm or less and soil particles having a particle size exceeding 75 μm, and contamination of the separated soil particles In the step of determining the level (A-3) and the step (A-3), if the contamination level exceeds the reference value, the soil particles are selected and the foreign matter is removed (A-8). Rub the dirt particles after removing the foreign matter. Step (A-4), the second rinsing step (A-5) for rinsing the sand particles after scrubbing and separating them into suspended water and fine sand particles containing fine soil particles, and the separated sand particles A step (A-6) for re-determining the contamination level of the soil, and the soil particles are regenerated as washing soil on condition that the contamination level becomes a reference value or less by the determination in the step (A-6). utilized, the step aqueous suspension separated by the (a-5) with separate water suspension and the step (a-2), the該懸turbid aggregate separation and concentration by adding a coagulant 50 to 5000 ppm, the Through a step (B-1) for separating flocs and aggregated water, which are aggregates of fine soil particles, and a step (B-2) for dehydrating the flocs and separating them into fine soil particles and separated water Containing harmful substances characterized by obtaining fine soil particles enriched with said harmful substances It is a method of purifying contaminated soil.

請求項５にかかる発明は、有害物質を含有する汚染土壌から有害物質を除去し、洗浄土砂と有害物質の濃縮した微細土粒子とに分離し、洗浄土砂を再生利用に供し、かつ有害物質の濃縮した微細土粒子を回収処理する汚染土壌の浄化方法であって、前記有害物質を含有する汚染土壌に水と添加剤を添加して混合し、スラリーとする工程（Ａ−１）と、該スラリーを濯いで、粒子径が７５μｍ以下の微細土粒子を含む懸濁水と、粒子径が７５μｍを超える土砂粒子とに分離する第１濯ぎ工程（Ａ−２）と、分離した前記土砂粒子の汚染レベルを判定する工程（Ａ−３）と、該工程（Ａ−３）において、汚染レベルが基準値を超えるのであれば、この土砂粒子を選別して、異物を除去する工程（Ａ−８）と、この異物除去後の土砂粒子に添加剤を添加して擦りもみする工程（Ａ−４’）と、この擦りもみ後の土砂粒子を吸着反応槽に送り、攪拌させる工程（Ａ−７）と、この擦りもみ後の土砂粒子を濯いで、微細土粒子を含む懸濁水と土砂粒子とに分離する第２濯ぎ工程（Ａ−５）と、分離した前記土砂粒子の汚染レベルを再度判定する工程（Ａ−６）とを有し、該工程（Ａ−６）での判定により汚染レベルが基準値以下となったことを条件としてその土砂粒子を洗浄土砂として再生利用し、前記工程（Ａ−５）で分離した懸濁水と前記工程（Ａ−２）で分離した懸濁水に、５０〜５０００ｐｐｍの凝集剤を添加して該懸濁水を凝集分離濃縮し、前記微細土粒子の集合体であるフロックと分離水とに分離する工程（Ｂ−１）と、該フロックを脱水処理し、微細土粒子と分離水とに分離する工程（Ｂ−２）とを経て、前記有害物質の濃縮した微細土粒子を得ることを特徴とする有害物質を含有する汚染土壌の浄化方法である。 The invention according to claim 5 removes harmful substances from contaminated soil containing harmful substances, separates them into washed soil and fine soil particles enriched with harmful substances, recycles the washed soil and recycles harmful substances. A method for purifying contaminated soil that collects and concentrates fine soil particles, wherein water and additives are added to and mixed with the contaminated soil containing the harmful substances to form a slurry (A-1), A first rinsing step (A-2) in which the slurry is rinsed and separated into suspended water containing fine soil particles having a particle size of 75 μm or less and soil particles having a particle size exceeding 75 μm, and contamination of the separated soil particles In the step of determining the level (A-3) and the step (A-3), if the contamination level exceeds the reference value, the soil particles are selected and the foreign matter is removed (A-8). Add additives to the soil particles after removing the foreign matter. A step of adding and rubbing (A-4 ′), a step of sending and stirring the sand particles after the rubbing to the adsorption reaction tank (A-7), and rinsing the sand particles after the rubbing, A second rinsing step (A-5) for separating the suspended water containing fine soil particles and the sand particles, and a step (A-6) for re-determining the contamination level of the separated soil particles. On the condition that the contamination level is equal to or lower than the reference value by the determination in (A-6) , the earth and sand particles are recycled as washing earth and sand , and the suspended water separated in the step (A-5) and the step (A (2) a step of adding 50 to 5000 ppm of a flocculant to the suspension water separated in step -2), coagulating and concentrating the suspension water, and separating it into flocs and separation water , which are aggregates of the fine soil particles (B- 1), the flock dehydrated, is separated into a fine soil particles and separated water Extent through the (B-2), a method of purifying contaminated soil containing harmful substances, characterized in that to obtain a concentrated fine soil particles of the toxic substances.

請求項６にかかる発明は、前記工程（Ｂ−１）および前記工程（Ｂ−２）において分離した分離水を、少なくとも前記工程（Ａ−１）、前記工程（Ａ−２）、前記工程（Ａ−４）または前記工程（Ａ−４'）、前記工程（Ａ−５）のいずれかで添加する水として再利用する請求項１〜５のいずれか一項に記載の有害物質を含有する汚染土壌の浄化方法である。 In the invention according to claim 6, the separated water separated in the step (B-1) and the step (B-2) is at least the step (A-1), the step (A-2), the step ( The hazardous substance according to any one of claims 1 to 5, which is reused as water to be added in any of A-4), the step (A-4 ') and the step (A-5). It is a purification method for contaminated soil.

請求項７にかかる発明は、前記添加剤が、竹炭、泥炭、亜炭、ヤシ殻炭、瀝青炭からなる群から選ばれる少なくとも１種以上の活性炭である請求項１〜６のいずれか一項に記載の有害物質を含有する汚染土壌の浄化方法である。 The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the additive is at least one activated carbon selected from the group consisting of bamboo charcoal, peat, lignite, coconut shell charcoal, and bituminous coal. It is a purification method for contaminated soil containing noxious substances.

本発明の浄化方法によれば、汚染土壌から有害物質を除去し、洗浄土砂と有害物質の濃縮した微細土粒子とに分離することにより、洗浄土砂の再利用を図ることができ、また有害物質は微細土粒子に濃縮しているため、この微細土粒子を回収処理することにより、安全で安価に処理を行うことができる。また、汚染物質の特性ごとに添加剤の種類、濃度を変えることにより、複合汚染土壌に対しても適用することができる。 According to the purification method of the present invention, by removing harmful substances from contaminated soil and separating them into washed soil and fine soil particles enriched with harmful substances, the washed soil can be reused. Is concentrated in fine soil particles, and by collecting the fine soil particles, the treatment can be performed safely and inexpensively. Moreover, it can apply also to composite contaminated soil by changing the kind and density | concentration of an additive for every characteristic of a pollutant.

本発明は、従来の汚染土壌の水洗浄では処理の難しかった複合汚染土壌や、細粒分の分離だけでは土壌環境基準値を満たさないような土砂粒子に付着している有害物質及び微量成分を含む汚染土壌の水洗浄による浄化の方法を実現したものである。以下、本発明の有害物質を含有する汚染土壌の浄化方法について、図面に基づき詳細に説明する。
なお、以下の説明および図面において、異なる工程に関連する複数の添加剤、土砂粒子、懸濁水、分離水については、必要に応じてそれぞれに（１）あるいは（２）の記号を付して区別する。 The present invention eliminates harmful substances and trace components adhering to complex contaminated soil, which has been difficult to treat with conventional water washing of contaminated soil, and soil particles that do not meet the soil environmental standard values only by separating fine particles. This is a method for purifying contaminated soil by washing with water. Hereinafter, the purification method for contaminated soil containing a harmful substance of the present invention will be described in detail with reference to the drawings.
In the following description and drawings, a plurality of additives, earth and sand particles, suspended water, and separated water related to different processes are distinguished from each other by adding (1) or (2) as necessary. To do.

［第１の実施形態］
図１は、第１の実施形態に係る有害物質を含有する汚染土壌の浄化方法の工程図である。本実施形態は、請求項１に記載の発明に対応するものである。本実施形態に係る汚染土壌の浄化方法は、有害物質を含有する汚染土壌に水と添加剤（１）を添加して混合し、スラリーとする工程（Ａ−１）と、該スラリーを濯いで、微細土粒子（後述するように粒子径が７５μｍ以下のもの）を含む懸濁水（１）と、土砂粒子（１）（同、粒子径が７５μｍを超えるもの）とに分離する第１濯ぎ工程（Ａ−２）と、分離した前記土砂粒子（１）の汚染レベルを判定する工程（Ａ−３）とを有し、該工程（Ａ−３）において、汚染レベルが基準値以下となったことを条件にこの土砂粒子（１）を洗浄土砂として再生利用に供し（汚染レベルが基準値を超える場合については後述）、一方、前記工程（Ａ−２）で除去した懸濁水（１）に５０〜５０００ｐｐｍの凝集剤を添加して凝集分離濃縮し、微細土粒子の集合体であるフロックと分離水（１）とに分離する工程（Ｂ−１）と、該フロックを脱水処理し、微細土粒子（脱水ケーキ）と分離水（２）とに分離する工程（Ｂ−２）とを経て、前記有害物質の濃縮した微細土粒子を得るものである。 [First Embodiment]
FIG. 1 is a process diagram of a method for purifying contaminated soil containing harmful substances according to the first embodiment. This embodiment corresponds to the invention described in claim 1. In the method for purifying contaminated soil according to this embodiment, water and additive (1) are added to and mixed with contaminated soil containing harmful substances to form a slurry (A-1), and the slurry is rinsed. , A first rinsing step for separating into suspended water (1) containing fine soil particles (having a particle diameter of 75 μm or less as described later) and earth and sand particles (1) (having a particle diameter exceeding 75 μm). (A-2) and a step (A-3) for determining the contamination level of the separated earth and sand particles (1), and in this step (A-3), the contamination level was below the reference value . it was subjected to recycle as cleaning soil the soil particles (1) on condition (described later if the contamination level is higher than the reference value), whereas, in the step (a-2) suspended water was removed by (1) and to aggregate separation and concentration added 50~5000ppm flocculant, fine soil particles Step a step of separating the floc a collection separated water (1) and (B-1), the flock dehydrated, is separated into a fine soil particles (dehydrated cake) and separated water (2) (B -2) to obtain fine soil particles enriched with the harmful substances.

浄化対象となる汚染土壌は、有害物質を含有するものであり、このような有害物質としては、ダイオキシン類、第一種特定有害物質にあたる有機化合物、第二種特定有害物質にあたる重金属等が挙げられる。なお、ダイオキシン類対策特別措置法においては、ポリ塩化ジベンゾ−パラ−ジオキシン（ＰＣＤＤ）及びポリ塩化ジベンゾフラン（ＰＣＤＦ）にコプラナーポリ塩化ビフェニル（コプラナーＰＣＢ）を含めて、“ダイオキシン類”と定義している。ＰＣＤＤは７５種類、ＰＣＤＦは１３５種類、コプラナーＰＣＢは十数種類の異性体があるが、これらのうち毒性があるとみなされているのは２９種類である。
また、第一種特定有害物質にあたる有機化合物としては、四塩化炭素、１，２−ジクロロエタン、１，１−ジクロロエチレン、シス−１，２−ジクロロエチレン、１，３−ジクロロプロペン、ジクロロメタン、トリクロロエチレン、１，１，１−トリクロロエタン、１，１，２−トリクロロエタン、テトラクロロエチレン、ベンゼンが挙げられる。
また、第二種特定有害物質にあたる重金属としては、カドミウム及びその化合物、六価クロム化合物、シアン化合物、水銀及びその化合物、セレン及びその化合物、鉛及びその化合物、砒素及びその化合物、ふっ素及びその化合物、ほう素及びその化合物が挙げられる。 Contaminated soil to be purified contains toxic substances, and examples of such toxic substances include dioxins, organic compounds corresponding to Class I Specified Hazardous Substances, heavy metals corresponding to Class II Specified Hazardous Substances, etc. . In addition, in the special measures law for dioxins, polychlorinated dibenzo-para-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF), including coplanar polychlorinated biphenyl (coplanar PCB), are defined as “dioxins”. . There are 75 types of PCDD, 135 types of PCDF, and dozens of isomers of coplanar PCB, of which 29 are considered toxic.
In addition, the organic compounds corresponding to the first class specific harmful substances include carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethylene, cis-1,2-dichloroethylene, 1,3-dichloropropene, dichloromethane, trichloroethylene, 1 1,1-trichloroethane, 1,1,2-trichloroethane, tetrachloroethylene, and benzene.
In addition, as heavy metals corresponding to the second type of specified hazardous substances, cadmium and its compounds, hexavalent chromium compounds, cyanide compounds, mercury and its compounds, selenium and its compounds, lead and its compounds, arsenic and its compounds, fluorine and its compounds , Boron and its compounds.

また、汚染土壌は、農業用地、工業用地、市街地、住宅地等のすべての土地の土壌である。有害物質により人工的に高濃度に汚染された工場跡地のような土壌であっても構わないし、自然汚染の農地のような土壌であってもよい。 Moreover, the contaminated soil is soil of all land such as agricultural land, industrial land, urban area, residential area and the like. It may be a soil such as a factory site that is artificially contaminated with a harmful substance at a high concentration, or may be a soil such as a naturally contaminated farmland.

本実施形態は、有害物質を含有する汚染土壌から有害物質を除去し、洗浄土砂と有害物質の濃縮した微細土粒子とに分離し、洗浄土砂を再生利用に供し、かつ有害物質の濃縮した微細土粒子を回収処理する汚染土壌の浄化方法である。したがって、洗浄土砂を得る工程Ａと有害物質の濃縮した微細土粒子を得る工程Ｂとに大きく分けられる。まず、洗浄土砂を得る工程Ａについて説明する。 This embodiment removes harmful substances from contaminated soil containing harmful substances, separates them into washed soil and fine earth particles enriched with harmful substances, recycles the washed earth and sand and concentrates fine substances with concentrated harmful substances. This is a method for purifying contaminated soil by collecting soil particles. Therefore, it is roughly divided into a process A for obtaining washed soil and a process B for obtaining fine soil particles enriched with harmful substances. First, the process A for obtaining washed soil will be described.

工程（Ａ−１）では、汚染土壌に水と添加剤（１）を添加してスラリー化混合槽で混合し、スラリー（泥水）とする。具体的には土壌の１〜１０倍の水を加え、土粒子を個々の粒子に解こうする。スラリー化の水量は１〜６倍がより好ましく、３〜５倍が特に好ましい。スラリー化混合攪拌には、ポンプ攪拌、プロペラ式攪拌機等土粒子を分散するものならば、いかなる装置も用いることができる。また、この混合撹伴時間は、２０〜６０分が好ましく、添加剤として吸着剤を添加した場合は、３０〜４０分がより好ましい。また、土粒子の塊をほぐす程度の攪拌力及び懸濁状態を確保する程度の攪拌力を必要とする。
工程（Ａ−１）で汚染土壌を十分にスラリー化し、土粒子を分散させることにより、微細土粒子の除去効率を向上させ、洗浄土砂の浄化度を向上させることができる。
また、この工程（Ａ−１）の前に、直径φ２０ｍｍ以上の礫や異物（木片、コンクリートがら等）をあらかじめ取り除いておくのが好ましい。ダイオキシン類は、油分に溶解して、木片、コンクリートがら等の異物に付着しやすいため、あらかじめ直径φ２０ｍｍ以上の異物除去を行うことにより、土砂粒子の浄化効率を向上させることができる。 In step (A-1), water and additive (1) are added to the contaminated soil and mixed in a slurry mixing tank to obtain slurry (muddy water). Specifically, 1 to 10 times as much water as the soil is added to break up the soil particles into individual particles. The amount of water for slurrying is more preferably 1 to 6 times, and particularly preferably 3 to 5 times. Any device can be used for the slurry mixing and mixing as long as it disperses the soil particles such as a pump stirring and a propeller stirrer. Further, the mixing and stirring time is preferably 20 to 60 minutes, and more preferably 30 to 40 minutes when an adsorbent is added as an additive. Moreover, the stirring force of the grade which loosens the lump of soil particles, and the stirring force of the grade which ensures a suspended state are required.
By sufficiently slurrying the contaminated soil in step (A-1) and dispersing the soil particles, the removal efficiency of the fine soil particles can be improved and the purification degree of the washed soil can be improved.
Further, before this step (A-1), it is preferable to remove in advance gravel having a diameter of 20 mm or more and foreign matters (wood pieces, concrete waste, etc.). Dioxins dissolve in oil and easily adhere to foreign matters such as wood chips and concrete debris. Therefore, the removal efficiency of soil particles can be improved by removing foreign matters having a diameter of φ20 mm or more in advance.

スラリー化混合槽には各種の添加剤（１）を加えることができる。このような添加剤（１）としては、界面活性剤、吸着剤、キレート剤、水等が挙げられる。添加剤（１）が水の場合とは、実質的には汚染土壌にスラリー化用の水しか添加しない場合である。土粒子の分散解こう、油脂の溶解を目的とした場合、添加剤（１）としては、界面活性剤を添加するのが好ましい。このような界面活性剤としては、例えば、ヘキサメタリン酸ナトリウム、トリポリリン酸ナトリウム、フミン酸、リグニンスルフォン酸ナトリウム、ポリアクリル酸ナトリウム、ポリカルボン酸共重合体塩、ポリカルボン酸塩、アニオン系高分子活性剤と無機多価金属複塩の混合物等から条件に合った薬剤を選定する。界面活性剤の添加量は、土壌質量に対して、０．１〜４質量％であるのが好ましい。 Various additives (1) can be added to the slurry mixing tank. Examples of such additive (1) include a surfactant, an adsorbent, a chelating agent, and water. The case where the additive (1) is water is a case where substantially only water for slurrying is added to the contaminated soil. For the purpose of dispersing the soil particles and dissolving the fats and oils, it is preferable to add a surfactant as the additive (1). Examples of such surfactants include sodium hexametaphosphate, sodium tripolyphosphate, humic acid, sodium lignin sulfonate, sodium polyacrylate, polycarboxylic acid copolymer salt, polycarboxylate, and anionic polymer activity. Select a drug that meets the conditions from a mixture of the agent and the inorganic polyvalent metal double salt. It is preferable that the addition amount of surfactant is 0.1-4 mass% with respect to soil mass.

また、有害物質の吸着・固定化を目的とした場合、添加剤（１）としては、キレート剤や吸着剤を添加するのが好ましい。キレート剤としては、ＥＤＴＡ、高分子系液体キレート等が挙げられる。また、吸着剤としては、有害物質の種類や濃度により選定するが、粉末活性炭、粒状活性炭、ゼオライト、磁性吸着剤、合成吸着剤等が適宜選定される。活性炭としては、竹炭、泥炭、亜炭、ヤシ殻炭、瀝青炭からなる群から選ばれる少なくとも１種以上であるのが好ましく、空隙径が大きい点から、泥炭がより好ましい。また、粉末活性炭が好ましい。
吸着剤の添加量は、スラリー質量に対して、０．０５〜５質量％であるのが好ましく、０．１〜２質量％であるのがより好ましい。吸着剤の添加量を０．０５〜５質量％とすることにより、スラリー化の促進及びその後の作業の安全性を高めることができる。 When the purpose is adsorption / immobilization of harmful substances, it is preferable to add a chelating agent or an adsorbent as the additive (1). Examples of the chelating agent include EDTA and polymer liquid chelate. The adsorbent is selected depending on the type and concentration of the harmful substance, and powdered activated carbon, granular activated carbon, zeolite, magnetic adsorbent, synthetic adsorbent and the like are appropriately selected. The activated carbon is preferably at least one selected from the group consisting of bamboo charcoal, peat, lignite, coconut shell charcoal, and bituminous coal, and peat is more preferable from the viewpoint of a large gap diameter. Moreover, powdered activated carbon is preferable.
The addition amount of the adsorbent is preferably 0.05 to 5% by mass and more preferably 0.1 to 2% by mass with respect to the slurry mass. By making the addition amount of the adsorbent 0.05 to 5% by mass, the promotion of slurrying and the safety of the subsequent work can be enhanced.

スラリー化混合時に添加した吸着剤は、次の第１濯ぎ工程（Ａ−２）で、懸濁水としてすべて分離除去する。そのため、吸着剤は、懸濁水として分離できる比重、粒径に調整されているものが好ましい。具体的には、粒子径１００μｍ以下、比重２．０以下であるのが好ましく、比重が１．５〜２．０であるのがより好ましい。
スラリー化時に有害物質を吸着する添加剤（１）を添加することにより、水溶性の有害物質や揮発性有害物質の複合汚染土壌を浄化することができる。また、スラリー化時に有害物質や悪臭物質を吸着する添加剤（１）を添加することにより、浄化作業の安全性及び作業環境を改善することができる。 The adsorbent added during the slurry mixing is separated and removed as suspended water in the next first rinsing step (A-2). Therefore, the adsorbent is preferably adjusted to have a specific gravity and particle size that can be separated as suspended water. Specifically, the particle diameter is preferably 100 μm or less and the specific gravity is 2.0 or less, and the specific gravity is more preferably 1.5 to 2.0.
By adding the additive (1) that adsorbs harmful substances during slurrying, it is possible to purify complex contaminated soil of water-soluble harmful substances and volatile harmful substances. Further, by adding the additive (1) that adsorbs harmful substances and malodorous substances during slurrying, the safety of the purification work and the working environment can be improved.

次いで、第１濯ぎ工程（Ａ−２）では、工程（Ａ−１）で得たスラリーを濯いで、微細土粒子を含む懸濁水（１）と土砂粒子（１）とに分離する。つまり、微細土粒子を懸濁水（１）として土砂粒子（２）から除去する。この微細土粒子（以下、微粒子という場合がある）とは、粒子径７５μｍ以下のものをいい、土壌中の土粒子の他に、添加剤として加えた吸着剤等も含まれる。これらは、水中で沈降が遅いため、懸濁水（１）となる。一方、粒子径７５μｍを超えるものは、比重が２．５〜２．９程度であり、土砂粒子（１）として沈降する。有害物質は、土壌中の７５μｍ以下の微粒子に大部分が存在しており、これらは吸着剤に吸着することから、微粒子とともに、あるいは微粒子・吸着剤に吸着して懸濁水（１）へと移行する。したがって、この粒子径７５μｍ以下の微粒子を水に懸濁させた状態のまま分離することで、有害物質を土壌から除去することができる。
この浄化方法では、土粒子の構成からみて、土壌中における粒子径７５μｍを超える微粒子の含有率が６０％以上であると有利であり、洗浄分離によるコストメリット及び洗浄土砂の再利用に効果的な観点から、７０％以上であるのが好ましい。 Next, in the first rinsing step (A-2), the slurry obtained in the step (A-1) is rinsed and separated into suspended water (1) containing fine soil particles and earth and sand particles (1) . That is, the fine soil particles are removed from the sediment particles (2) as suspended water (1). The fine soil particles (hereinafter sometimes referred to as fine particles) refer to particles having a particle size of 75 μm or less, and include adsorbents added as additives in addition to soil particles in the soil. Since these settle slowly in water, they become suspended water (1). On the other hand, those having a particle diameter exceeding 75 μm have a specific gravity of about 2.5 to 2.9 and settle as earth and sand particles (1). Most of the harmful substances exist in the fine particles of 75 μm or less in the soil, and these adsorb to the adsorbent, so they move to the suspended water (1) together with the fine particles or adsorbed to the fine particles / adsorbent. To do. Therefore, by separating the fine particles having a particle diameter of 75 μm or less while being suspended in water, harmful substances can be removed from the soil.
In this purification method, it is advantageous that the content of fine particles having a particle diameter exceeding 75 μm in the soil is 60% or more in view of the structure of the soil particles, which is effective for cost merit by washing separation and reuse of the washed soil. From the viewpoint, it is preferably 70% or more.

この第１濯ぎ工程（Ａ−２）では、骨材洗浄プラントで採用されている砂分級機を用いることができる。砂分級機は、土砂粒子（１）の水切り促進と懸濁水（１）の効率的除去を行うため、２連式や３連式の濯ぎ装置等を採用してもよい。２連式濯ぎ装置の場合、１連目の濯ぎでは、土壌に対し水量は１〜８倍が好ましく、２連目の濯ぎでは、水量は土壌と等量であるのが好ましい。この第１濯ぎ工程（Ａ−２）で、スラリー化混合時に添加した界面活性剤及び吸着剤は全て懸濁水（１）として土砂粒子（１）から分離除去される。
スラリー化時に有害物質を吸着する粉末活性炭を添加して、有害物質を微細土粒子と粉末活性炭に捕集し、これを懸濁水（１）として土砂粒子（１）から分離することにより、洗浄土砂への粉末活性炭や添加剤の残留を防止することができる。 In the first rinsing step (A-2), a sand classifier employed in an aggregate cleaning plant can be used. The sand classifier may employ a double-type or triple-type rinsing device or the like in order to promote draining of the earth and sand particles (1) and to efficiently remove the suspended water (1). In the case of a double rinsing apparatus, the amount of water in the first rinsing is preferably 1 to 8 times that of the soil, and in the second rinsing, the amount of water is preferably equal to the soil. In this first rinsing step (A-2), all of the surfactant and adsorbent added during slurry mixing are separated and removed from the sediment particles (1) as suspended water (1).
Washing earth and sand by adding powdered activated carbon that adsorbs harmful substances during slurrying, collecting the harmful substances in fine earth particles and powdered activated carbon, and separating them from the earth and sand particles (1) as suspended water (1) It is possible to prevent residual powdered activated carbon and additives.

次いで、汚染レベルを判定する工程（Ａ−３）では、分離したこの土砂粒子（１）の汚染レベルを判定する。汚染レベルが基準値以下であれば、この土砂粒子（１）を洗浄土砂とし、処理が完了し、この洗浄土砂は再利用に供される。土砂粒子（１）の汚染レベルの判定は、ダイオキシン類については、平成１２年１月環境庁水質保全局土壌農薬課発行の「ダイオキシン類に係る土壌調査測定マニュアル」にしたがって公定法で行ってもよいし、バイオアッセイ等の簡易法で行ってもよい。ダイオキシン類対策特別措置法によれば、土壌環境基準値は１０００ｐｇ−ＴＥＱ／ｇ以下である。ここで、ＴＥＱとは、毒性等量（Toxicity Equivalency Quantity）をいい、最も毒性が強い２，３，７，８−ＴＣＤＤ（ＰＣＤＤの１種）の毒性等価係数（ＴＥＦ：Toxicity Equivalency Factor）を１として、他のダイオキシン類のＴＥＦを換算し、ダイオキシン類の各異性体濃度に各ＴＥＦ値を掛け合わせた数値の総和値である。
また、第二種特定有害物質の土壌含有量基準値は、１５〜４０００ｍｇ／ｋｇ以下であり、第一種特定有害物質については、土壌溶出量の基準として、０．００２〜１ｍｇ／Ｌ以下と規定されている。なお、工程（Ａ−３）において、汚染レベルが基準値を超える場合については、後述する。 Next, in the step (A-3) of determining the contamination level, the contamination level of the separated sediment particles (1) is determined. If the contamination level is lower than the reference value, this earth and sand particle (1) is used as washing earth and the treatment is completed, and this washing earth and sand is used for reuse. Judgment of contamination level of earth and sand particles (1) can be done by the official method for dioxins according to the “Soil Survey and Measurement Manual for Dioxins” published by the Environment Agency Water Quality Conservation Bureau, Soil Agricultural Chemicals Section in January 2000. Alternatively, a simple method such as a bioassay may be used. According to the Act on Special Measures against Dioxins, the soil environment standard value is 1000 pg-TEQ / g or less. Here, TEQ means Toxicity Equivalency Quantity, and the toxicity equivalent coefficient (TEF: Toxicity Equivalency Factor) of 2,3,7,8-TCDD (one type of PCDD) having the strongest toxicity is 1. Is the sum of numerical values obtained by converting the TEFs of other dioxins and multiplying each isomer concentration of the dioxins by each TEF value.
In addition, the soil content standard value of the second type specific harmful substance is 15 to 4000 mg / kg or less, and the first type specific harmful substance is 0.002 to 1 mg / L or less as the standard of the soil elution amount. It is prescribed. In the step (A-3), the case where the contamination level exceeds the reference value will be described later.

一方、有害物質の濃縮した微細土粒子を得る工程Ｂについては、まず工程（Ｂ−１）で、前記工程（Ａ−２）で除去した懸濁水（１）を、微細土粒子濃度を調整して濁水処理装置に送り、凝集剤を添加して凝集分離濃縮し、フロックと分離水（１）とに分離する。このような凝集剤としては、無機系凝集剤、有機系凝集剤を単独又は組合わせて用いることができる。無機系凝集剤としては、例えば、硫酸アルミニウム、ポリ塩化アルミニウム、鉄塩等が挙げられ、有機系凝集剤としては、例えば、ポリアクリルアミド、ポリアクリル酸等が挙げられる。また、凝集剤の添加量は、懸濁水に対して５０〜５０００ｐｐｍとする。
分離水（１）は、工程（Ａ−１）の土壌のスラリー化用水、工程（Ａ−２）の第１濯ぎ用水、後述する工程（Ａ−４）の擦りもみ用水、後述する工程（Ａ−５）の第２濯ぎ用水として再利用される。
吸着剤である粉末活性炭を含有した懸濁水（１）から凝集処理を行い、色、臭気、余剰凝集剤等を除去することにより、極めて良質な分離水（１）を得ることができる。 On the other hand, for step B to obtain fine soil particles enriched with harmful substances, first, in step (B-1), the suspended water (1) removed in step (A-2) is adjusted to a fine soil particle concentration. Then, it is sent to a turbid water treatment apparatus, a flocculant is added, and the flocculant is separated and concentrated to separate into floc and separated water (1). As such flocculants, inorganic flocculants and organic flocculants can be used alone or in combination. Examples of the inorganic flocculant include aluminum sulfate, polyaluminum chloride, and iron salt. Examples of the organic flocculant include polyacrylamide and polyacrylic acid. Moreover, the addition amount of a flocculant shall be 50-5000 ppm with respect to suspension water .
The separated water (1) is water for slurrying the soil in step (A-1), water for first rinsing in step (A-2), water for rubbing in step (A-4) described later, and step (A) described later. -5) Reused as second rinsing water.
By performing a coagulation treatment from the suspended water (1) containing powdered activated carbon that is an adsorbent and removing the color, odor, surplus coagulant and the like, it is possible to obtain very good quality separated water (1).

沈降したフロックは、次の工程（Ｂ−２）において、再凝集処理を行ってフロックの水切りを促進させ、機械的脱水機で脱水処理し、有害物質の濃縮した微細土粒子（脱水ケーキ）と分離水（２）とに分離する。この分離水（２）は、分離水（１）と共に再利用される。有害物質の濃縮した微細土粒子は、回収され、最終的には溶融炉での熱分解処理や封じ込め処理が行われる。有害物質は、吸着剤、微粒子と共にフロックに濃縮され、微細土粒子（脱水ケーキ）となり、分離水（１）及び分離水（２）からは有害物質は除去されるため、極めて水質の良好な分離水（１）及び分離水（２）が得られる。例えば、ダイオキシン類でいえば、排出水の基準値１０ｐｇ−ＴＥＱ／Ｌ以下である。この分析は、ＪＩＳＫ０３１２（１９９９）の「工業用水・工場排水中のダイオキシン類及びコプラナーＰＣＢの測定方法」にしたがって、公定法で行ってもよいし、簡易法（迅速法）で行ってもよい。 In the next step (B-2), the settled floc is re-agglomerated to promote draining of the floc, dehydrated with a mechanical dehydrator, and fine soil particles (dehydrated cake) enriched with harmful substances. Separated into separated water (2). This separated water (2) is reused together with the separated water (1). Fine soil particles enriched with harmful substances are collected and finally subjected to thermal decomposition and containment in a melting furnace. Hazardous substances are concentrated in floc together with adsorbents and fine particles to form fine soil particles (dehydrated cake). Since the harmful substances are removed from the separated water (1) and separated water (2), the separation is extremely good in water quality. Water (1) and separated water (2) are obtained. For example, in the case of dioxins, the reference value of discharged water is 10 pg-TEQ / L or less. This analysis may be performed by an official method or a simple method (rapid method) according to “Measurement method of dioxins and coplanar PCB in industrial water / factory waste water” of JIS K0312 (1999). .

吸着剤である粉末活性炭を含有した懸濁水（１）から得たフロックは、脱水性が良好であるため、機械式脱水機の脱水効率を改善することができる。従来法と比べ、有害物質の濃縮した微細土粒子はコンパクトで軽量であり、また有害物質が強固に安定して吸着しているため、安定したハンドリングを行うことができる。
また、分離水（１）及び分離水（２）を、前記工程（Ａ−１）、工程（Ａ−２）、工程（Ａ−４）、工程（Ａ−５）のいずれかで添加する水として再利用することにより、コストをより削減することができる。 Since the floc obtained from the suspended water (1) containing powdered activated carbon that is an adsorbent has good dewaterability, the dewatering efficiency of the mechanical dehydrator can be improved. Compared with the conventional method, the fine soil particles enriched with harmful substances are compact and lightweight, and the harmful substances are firmly and stably adsorbed, so that stable handling can be performed.
Moreover, the water which adds separation water (1) and separation water (2) in either of the said process (A-1), a process (A-2), a process (A-4), and a process (A-5). By reusing as, cost can be further reduced.

本実施形態の浄化方法は、汚染地に処理システムを設置してオンサイトで行ってもよいし、汚染土壌を処理センター等に運搬して行ってもよい。 The purification method of this embodiment may be performed on-site by installing a treatment system in a contaminated area, or may be performed by transporting contaminated soil to a treatment center or the like.

また、本実施形態では、汚染土壌から有害物質を除去し、洗浄土砂と有害物質の濃縮した微細土粒子とに分離することにより、洗浄土砂の再利用を図ることができる。また、有害物質は微細土粒子に濃縮しているため、この微細土粒子を回収処理することにより、安全で安価に処理を行うことができる。また、汚染物質の特性ごとに添加剤の種類、濃度を変えることにより、複合汚染土壌に対しても適用することができる。さらに、本実施形態で使用する各装置・機材は単純で取扱いが容易であるため、装置及びメンテナンスのコストダウンを図ることができる。 Moreover, in this embodiment, reuse of washing | cleaning earth and sand can be aimed at by removing a harmful substance from contaminated soil, and isolate | separating into washing | cleaning earth and fine soil particles which the toxic substance concentrated. In addition, since harmful substances are concentrated in fine soil particles, the fine soil particles can be recovered and processed safely and inexpensively. Moreover, it can apply also to composite contaminated soil by changing the kind and density | concentration of an additive for every characteristic of a pollutant. Furthermore, since each apparatus and equipment used in the present embodiment is simple and easy to handle, the cost of the apparatus and maintenance can be reduced.

［第２の実施形態］
図２は、第２の実施形態に係る有害物質を含有する汚染土壌の浄化方法の工程図である。本実施形態は、請求項２に記載の発明に対応するものである。本実施形態に係る汚染土壌の浄化方法は、前記工程（Ａ−３）において、汚染レベルが基準値を超えるのであれば、この土砂粒子（１）を擦りもみする工程（Ａ−４）と、この擦りもみ後の土砂粒子を濯いで、微粒子（微細土粒子）と土砂粒子（２）とに分離し、該微粒子を懸濁水（２）として除去する第２濯ぎ工程（Ａ−５）と、分離した前記土砂粒子（２）の汚染レベルを再度判定する工程（Ａ−６）とを有し、該工程（Ａ−６）において、汚染レベルが基準値以下となったことを条件にこの土砂粒子（２）を洗浄土砂とし、前記工程（Ａ−５）で除去した懸濁水（２）を前記工程（Ａ−２）で除去した懸濁水（１）と共に凝集分離濃縮し、フロックと分離水（１）とに分離する工程（Ｂ−１）と、該フロックを脱水処理し、微細土粒子と分離水（２）とに分離する工程（Ｂ−２）とを経て、前記有害物質の濃縮した微細土粒子を得るものである。
本実施形態に係る汚染土壌の浄化方法は、工程（Ａ−３）において、汚染レベルが基準値を超えた場合の浄化方法であり、擦りもみする工程（Ａ−４）と第２濯ぎ工程（Ａ−５）を設けて汚染のさらなる低減化を図っている。汚染レベルを再度判定する工程（Ａ−６）は、工程（Ａ−３）と実質的に同一であり、擦りもみする工程（Ａ−４）と第２濯ぎ工程（Ａ−５）以外は、第１の実施形態と同じであるので、それらの説明は省略する。 [Second Embodiment]
FIG. 2 is a process diagram of a method for purifying contaminated soil containing harmful substances according to the second embodiment. This embodiment corresponds to the invention described in claim 2. If the contamination level exceeds the reference value in the step (A-3), the contaminated soil purification method according to the present embodiment is a step (A-4) of rubbing the earth and sand particles (1), A second rinsing step (A-5) for rinsing the sand particles after the scrubbing to separate fine particles (fine soil particles) and earth and sand particles (2) and removing the fine particles as suspended water (2); A step (A-6) of re-determining the level of contamination of the separated soil particles (2), and the soil level is determined on the condition that the level of contamination is below a reference value in the step (A-6). The particles (2) are washed earth and sand, and the suspended water (2) removed in the step (A-5) is coagulated, separated and concentrated together with the suspended water (1) removed in the step (A-2). (1) and the step (B-1), the floc is dehydrated, and fine soil particles And a process of separating the separated water and (2) (B-2), is intended to obtain a concentrated fine soil particles of the toxic substances.
The purification method for contaminated soil according to the present embodiment is a purification method when the contamination level exceeds the reference value in the step (A-3). The rubbing step (A-4) and the second rinsing step ( A-5) is provided to further reduce contamination. The step (A-6) of re-determining the contamination level is substantially the same as the step (A-3), except for the rubbing step (A-4) and the second rinsing step (A-5). Since they are the same as those in the first embodiment, descriptions thereof are omitted.

工程（Ａ−４）では、汚染レベルが基準値を超える土砂粒子（１）を擦りもみし、付着している有害物質の除去を行う。この付着物除去とは、土砂粒子同士に強制的な摩擦を与え擦りもむことであり、コンクリート混練ミキサーと同様の攪拌混合力を持つミキサー等を使用することができる。擦りもみ工程では１〜３０分の擦りもみを行う。また、添加する水量は土砂粒子（１）の０．１〜２倍であるのが好ましい。 In the step (A-4), the soil particles (1) having a contamination level exceeding the reference value are rubbed and the adhering harmful substances are removed. This adhering matter removal is to forcibly give friction between soil particles and to rub them, and it is possible to use a mixer having the same stirring and mixing power as a concrete kneading mixer. In the rubbing process, rubbing is performed for 1 to 30 minutes. The amount of water to be added is preferably 0.1 to 2 times that of the earth and sand particles (1).

次いで、第２濯ぎ工程（Ａ−５）では、この擦りもみ後の土砂粒子を濯いで、微粒子と土砂粒子（２）とに分離し、該微粒子を懸濁水（２）として除去する。第２濯ぎ工程（Ａ−５）で使用する砂分級機も基本的には第１濯ぎ工程と同様のものを用いることができるが、土砂粒子（２）の水切りをより十分に行うため、２連式又は３連式濯ぎ装置等を採用するのが好ましい。 Next, in the second rinsing step (A-5), the soil particles after rubbing are rinsed to separate them into fine particles and sediment particles (2), and the fine particles are removed as suspended water (2). The sand classifier used in the second rinsing step (A-5) can be basically the same as that used in the first rinsing step. However, in order to drain the earth and sand particles (2) more sufficiently, 2 It is preferable to employ a continuous or triple rinsing device.

第２濯ぎ工程（Ａ−５）で分離した前記土砂粒子（２）は、工程（Ａ−６）で再び汚染レベルの判定を行い、土壌環境基準値以下であれば処理完了となる。また、分離した懸濁水（２）は懸濁水（１）と共に、上述した工程（Ｂ−１）、工程（Ｂ−２）で処理される。 The soil particles (2) separated in the second rinsing step (A-5) are subjected to the contamination level determination again in the step (A-6). Moreover, the separated suspension water (2) is treated in the step (B-1) and the step (B-2) described above together with the suspension water (1).

本実施形態によれば、第１の実施形態では汚染レベルを低減できなかった土砂粒子の浄化効率を向上させることができる。 According to the present embodiment, it is possible to improve the purification efficiency of earth and sand particles that could not reduce the contamination level in the first embodiment.

［第３の実施形態］
図３は、第３の実施形態に係る有害物質を含有する汚染土壌の浄化方法の工程図である。本実施形態は、請求項３に記載の発明に対応するものである。本実施形態に係る汚染土壌の浄化方法は、第２の実施形態における工程（Ａ−４）を、この土砂粒子（１）に添加剤（２）を添加して擦りもみする工程（Ａ−４’）と、この擦りもみ後の土砂粒子を吸着反応槽に送り、攪拌させる工程（Ａ−７）としたものである。
本実施形態では、添加剤（２）を添加する擦りもみする工程（Ａ−４’）と攪拌させる工程（Ａ−７）を設けた以外は、第２の実施形態と同じであるので、それらの説明は省略する。 [Third Embodiment]
FIG. 3 is a process diagram of a purification method for contaminated soil containing harmful substances according to the third embodiment. This embodiment corresponds to the invention described in claim 3. In the method for purifying contaminated soil according to the present embodiment, the step (A-4) in the second embodiment is performed by adding the additive (2) to the earth and sand particles (1) and rubbing (A-4). ') And the step (A-7) in which the sand particles after the rubbing are fed to the adsorption reaction tank and stirred.
Since this embodiment is the same as the second embodiment except that a rubbing step (A-4 ′) for adding the additive (2) and a step (A-7) for stirring are provided, these are the same. Description of is omitted.

この工程（Ａ−４’）では、土砂粒子（１）に添加剤（２）を添加して擦りもみをする。この擦りもみでは、付着物である有害物質の除去を促進するため、付着物の特性に応じて添加剤（２）を添加するのが好ましい。添加剤（２）には、上述した添加剤（１）を同様に用いることができ、油分等が付着している場合は、苛性ソーダ水溶液や界面活性剤、洗剤（中性洗剤、アルカリ洗剤等）を添加するのが好ましい。ダイオキシン類等の超微量成分が付着している場合は、フミン酸やリグニンスルフォン酸を添加するのが好ましい。また、粒状活性炭、成型活性炭等の吸着剤を添加して擦りもみを行うことにより、活性炭の破砕を行うことで活性炭の吸着表面を増加させ、吸着効率を増すこともできる。擦りもみには、第２の実施形態で述べたのと同様の装置を使用することができる。 In this step (A-4 '), the additive (2) is added to the earth and sand particles (1) and rubbed. In this scrubbing, it is preferable to add the additive (2) according to the characteristics of the deposit in order to promote the removal of harmful substances as the deposit. As the additive (2), the above-mentioned additive (1) can be used in the same manner. When oil or the like is attached, a caustic soda aqueous solution, a surfactant, a detergent (neutral detergent, alkaline detergent, etc.) Is preferably added. When ultra trace components such as dioxins are attached, it is preferable to add humic acid or lignin sulfonic acid. Moreover, by adding an adsorbent such as granular activated carbon or molded activated carbon and carrying out scrubbing, the activated carbon can be crushed to increase the adsorption surface of the activated carbon and increase the adsorption efficiency. For scrubbing, an apparatus similar to that described in the second embodiment can be used.

１〜３０分の擦りもみを行った後、次の工程（Ａ−７）で、この擦りもみ後の土砂粒子を吸着反応槽に送り、水を１〜４倍加えた後、１０〜６０分、好ましくは３０分攪拌させる。この吸着反応槽には、さらに粉末活性炭等の吸着剤を添加して吸着反応を促進させてもよい。 After rubbing for 1 to 30 minutes, in the next step (A-7), the soil particles after the rubbing are sent to the adsorption reaction tank, and water is added 1 to 4 times, and then 10 to 60 minutes. The mixture is preferably stirred for 30 minutes. The adsorption reaction may be further promoted by adding an adsorbent such as powdered activated carbon to the adsorption reaction tank.

工程（Ａ−７）の後、第２の実施形態で述べたのと同様に第２濯ぎ工程（Ａ−５）と汚染レベルを再度判定する工程（Ａ−６）を行い、土砂粒子（２）の汚染レベルが、土壌環境基準値以下であれば処理完了となる。仮に、この工程（Ａ−６）においても、未だ汚染レベルが基準値を超える場合は、再び擦りもみする工程（Ａ−４’）から第２濯ぎ工程（Ａ−５）までを繰り返し行う。 After the step (A-7), the second rinsing step (A-5) and the step (A-6) for re-determining the contamination level are performed in the same manner as described in the second embodiment. If the contamination level is less than the soil environmental standard value, the treatment is completed. Even in this step (A-6), if the contamination level still exceeds the reference value, the steps from the rubbing step (A-4 ') to the second rinsing step (A-5) are repeated.

［第４の実施形態］
本実施形態は、請求項４に記載の発明に対応するものである。本実施形態に係る汚染土壌の浄化方法は、有害物質を含有する汚染土壌に水と添加剤（１）を添加して混合し、スラリーとする工程（Ａ−１）と、該スラリーを濯いで、微粒子と土砂粒子（１）とに分離し、該微粒子を懸濁水（１）として除去する第１濯ぎ工程（Ａ−２）と、分離した前記土砂粒子（１）の汚染レベルを判定する工程（Ａ−３）と、該工程（Ａ−３）において、汚染レベルが基準値を超えるのであれば、この土砂粒子（１）を選別して、異物を除去する工程（Ａ−８）と、この異物除去後の土砂粒子を擦りもみする工程（Ａ−４）と、この擦りもみ後の土砂粒子を濯いで、微粒子と土砂粒子（２）とに分離し、該微粒子を懸濁水（２）として除去する第２濯ぎ工程（Ａ−５）と、分離した前記土砂粒子（２）の汚染レベルを再度判定する工程（Ａ−６）とを有し、該工程（Ａ−６）において、汚染レベルが基準値以下であればこの土砂粒子（２）を洗浄土砂とし、前記工程（Ａ−５）で除去した懸濁水（２）を前記工程（Ａ−２）で除去した懸濁水（１）と共に凝集分離濃縮し、フロックと分離水（１）とに分離する工程（Ｂ−１）と、該フロックを脱水処理し、微細土粒子と分離水（２）とに分離する工程（Ｂ−２）とを経て、前記有害物質の濃縮した微細土粒子を得るものである。
本実施形態に係る汚染土壌の浄化方法は、第２の実施形態における工程（Ａ−４）の前に、土砂粒子（１）を選別して、異物を除去する工程（Ａ−８）を設けた以外は、第２の実施形態と同じであるので、それらの説明は省略する。 [Fourth Embodiment]
This embodiment corresponds to the invention described in claim 4. In the method for purifying contaminated soil according to this embodiment, water and additive (1) are added to and mixed with contaminated soil containing harmful substances to form a slurry (A-1), and the slurry is rinsed. , A first rinsing step (A-2) for separating fine particles and earth and sand particles (1) and removing the fine particles as suspended water (1), and a step of determining a contamination level of the separated earth and sand particles (1) In (A-3) and the step (A-3), if the contamination level exceeds the reference value, the step (A-8) of selecting the earth and sand particles (1) and removing foreign matters, The step (A-4) of rubbing the earth and sand particles after removing the foreign matter, the earth and sand particles after rubbing are rinsed and separated into fine particles and earth and sand particles (2), and the fine particles are suspended in water (2). As a second rinsing step (A-5) to be removed, and the contamination level of the separated sediment particles (2) Step (A-6), and in this step (A-6), if the contamination level is below the reference value, this earth and sand particle (2) is used as washing earth and said step (A-5) The suspension water (2) removed in step (B-1) is coagulated, separated and concentrated together with the suspension water (1) removed in the step (A-2) and separated into floc and separated water (1), The floc is dehydrated, and through the step (B-2) of separating into fine soil particles and separated water (2), fine soil particles enriched with the harmful substances are obtained.
The method for purifying contaminated soil according to the present embodiment includes a step (A-8) of selecting soil particles (1) and removing foreign matters before the step (A-4) in the second embodiment. Other than that, the second embodiment is the same as the second embodiment, and a description thereof will be omitted.

工程（Ａ−８）では、土砂粒子（１）を振動ふるいや比重選別機等の装置にかけて、もえがら、木屑、プラスチック類、軽石等の粒径の大きい異物や軽比重の異物を除去する。この異物除去後の土砂粒子は、上述した擦りもみする工程（Ａ−４）に送られる。ダイオキシン類は、もえがら、木屑、プラスチック類、軽石等に付着しやすい傾向があるため、異物除去を行うことにより、土砂粒子の浄化効率をさらに向上させることができる。 In the step (A-8), the earth and sand particles (1) are passed through an apparatus such as a vibrating screen or a specific gravity sorter to remove foreign substances having a large particle diameter such as gills, wood chips, plastics and pumice, and foreign substances having a low specific gravity. The earth and sand particles after removing the foreign matters are sent to the step (A-4) for rubbing. Since dioxins tend to adhere to gills, wood chips, plastics, pumice, and the like, the purification efficiency of earth and sand particles can be further improved by removing foreign substances.

［第５の実施形態］
図４は、第５の実施形態に係る有害物質を含有する汚染土壌の浄化方法の工程図である。本実施形態は、請求項５に記載の発明に対応するものである。本実施形態に係る汚染土壌の浄化方法は、有害物質を含有する汚染土壌に水と添加剤（１）を添加して混合し、スラリーとする工程（Ａ−１）と、該スラリーを濯いで、微粒子と土砂粒子（１）とに分離し、該微粒子を懸濁水（１）として除去する第１濯ぎ工程（Ａ−２）と、分離した前記土砂粒子（１）の汚染レベルを判定する工程（Ａ−３）と、該工程（Ａ−３）において、汚染レベルが基準値を超えるのであれば、この土砂粒子（１）を選別して、異物を除去する工程（Ａ−８）と、この異物除去後の土砂粒子に添加剤（２）を添加して擦りもみする工程（Ａ−４’）と、この擦りもみ後の土砂粒子を吸着反応槽に送り、攪拌させる工程（Ａ−７）と、この攪拌後の土砂粒子を濯いで、微粒子と土砂粒子（２）とに分離し、該微粒子を懸濁水（２）として除去する第２濯ぎ工程（Ａ−５）と、分離した前記土砂粒子（２）の汚染レベルを再度判定する工程（Ａ−６）とを有し、該工程（Ａ−６）において、汚染レベルが基準値以下であればこの土砂粒子（２）を洗浄土砂とし、前記工程（Ａ−５）で除去した懸濁水（２）を前記工程（Ａ−２）で除去した懸濁水（１）と共に凝集分離濃縮し、フロックと分離水（１）とに分離する工程（Ｂ−１）と、該フロックを脱水処理し、微細土粒子と分離水（２）とに分離する工程（Ｂ−２）とを経て、前記有害物質の濃縮した微細土粒子を得るものである。
本実施形態に係る汚染土壌の浄化方法は、第３の実施形態における工程（Ａ−４）の前に、土砂粒子（１）を選別して、異物を除去する工程（Ａ−８）を設けた以外は、第３の実施形態と同じであり、この異物を除去する工程（Ａ−８）も第４の実施形態で述べたのと同じであるので、それらの説明は省略する。 [Fifth Embodiment]
FIG. 4 is a process diagram of a purification method for contaminated soil containing harmful substances according to the fifth embodiment. This embodiment corresponds to the invention described in claim 5. In the method for purifying contaminated soil according to this embodiment, water and additive (1) are added to and mixed with contaminated soil containing harmful substances to form a slurry (A-1), and the slurry is rinsed. , A first rinsing step (A-2) for separating fine particles and earth and sand particles (1) and removing the fine particles as suspended water (1), and a step of determining a contamination level of the separated earth and sand particles (1) In (A-3) and the step (A-3), if the contamination level exceeds the reference value, the step (A-8) of selecting the earth and sand particles (1) and removing foreign matters, A step (A-4 ′) of adding the additive (2) to the soil particles after removing the foreign matters and rubbing them, and a step of sending the stirring sand particles to the adsorption reaction tank and stirring them (A-7) ) And the earth and sand particles after stirring are separated into fine particles and earth and sand particles (2). A second rinsing step (A-5) for removal as turbid water (2), and a step (A-6) for re-determining the contamination level of the separated earth and sand particles (2). ), If the contamination level is below the reference value, the sediment particles (2) are used as washing soil, and the suspended water (2) removed in the step (A-5) is removed in the step (A-2). A step (B-1) of coagulating, separating and concentrating with muddy water (1) to separate floc and separated water (1), and a step of dehydrating the floc and separating into fine soil particles and separated water (2) Through (B-2), fine soil particles in which the harmful substances are concentrated are obtained.
The method for purifying contaminated soil according to the present embodiment is provided with a step (A-8) of selecting soil particles (1) and removing foreign matters before the step (A-4) in the third embodiment. Except for the above, the third embodiment is the same as the third embodiment, and the step (A-8) for removing the foreign matter is also the same as that described in the fourth embodiment, so that the description thereof is omitted.

本実施形態によれば、有害物質を含有する汚染土壌の浄化効率をさらに向上させることができる。 According to the present embodiment, the purification efficiency of contaminated soil containing harmful substances can be further improved.

以下、実施例により、本発明をさらに詳しく説明する。本発明は、下記実施例に何ら制限されるものではない。 Hereinafter, the present invention will be described in more detail by way of examples. The present invention is not limited to the following examples.

４箇所の場所で汚染土壌を採取した。この採取した土壌試料を、ダイオキシン土壌（１）〜（４）と表記する。各採取試料（元土壌）のダイオキシン類含有量を、平成１２年１月環境庁水質保全局土壌農薬課発行の「ダイオキシン類に係る土壌調査測定マニュアル」にしたがって公定法及び簡易法で測定した。この分析値をＩで表記し、表１に各々示す。また、図５は、実施例において、試料を採取し、ダイオキシン類の分析を行った工程箇所をＩ〜ＶＩで表記した汚染土壌の浄化方法の工程図である。 Contaminated soil was collected at four locations. This collected soil sample is expressed as dioxin soil (1) to (4). The dioxin content of each sample (original soil) was measured by the official method and the simplified method according to the “Soil Survey and Measurement Manual for Dioxins” published by the Environment Agency, Water Quality Conservation Bureau, Soil Agrochemicals Division in January 2000. This analysis value is denoted by I and shown in Table 1, respectively. In addition, FIG. 5 is a process diagram of a method for purifying contaminated soil in which the sample of a sample and the analysis of dioxins in the examples are indicated by I to VI.

次いで、汚染土壌を５ｔ／ｈで掘削し、直径φ２０ｍｍ以上の礫、異物を除去した後、スラリー化混合攪拌槽内で４倍の水を添加して４０分間攪拌混合し、スラリーとした。
また、水と共に０．５質量％の粉末活性炭を加えて上記と同様の方法でスラリーを作製した。この時加えた粉末活性炭の種類は、表１にも示したが、泥炭Ｌ（嵩比重２００ｋｇ／ｍ^３、比表面積（Ｂ．Ｅ．Ｔ）１１５０ｍ^２／ｇ、粒度Ｄ_５０１０μｍ）、泥炭Ｍ（嵩比重６００ｋｇ／ｍ^３、比表面積（Ｂ．Ｅ．Ｔ）６００ｍ^２／ｇ、粒度Ｄ_５０３０μｍ）、亜炭（嵩比重５１０ｋｇ／ｍ^３、比表面積（Ｂ．Ｅ．Ｔ）６００ｍ^２／ｇ、粒度Ｄ_５０２５μｍ）、ヤシ殻炭（嵩比重５１０ｋｇ／ｍ^３、比表面積１１５０ｍ^２／ｇ）、瀝青炭（嵩比重４２０ｋｇ／ｍ^３、比表面積（Ｂ．Ｅ．Ｔ）１３００ｍ^２／ｇ、粒度Ｄ_５０１５μｍ）である。 Next, the contaminated soil was excavated at 5 t / h to remove gravel and foreign matter having a diameter of 20 mm or more, and then 4 times as much water was added in the slurry mixing and stirring tank, and stirred and mixed for 40 minutes to obtain a slurry.
Moreover, 0.5 mass% powdered activated carbon was added with water, and the slurry was produced by the same method as the above. The types of powdered activated carbon added at this time are also shown in Table 1. Peat L (bulk specific gravity 200 kg / m ³ , specific surface area (BET) 1150 m ² / g, particle size D ₅₀ 10 μm), peat M (Bulk specific gravity 600 kg / m ³ , specific surface area (BET) 600 m ² / g, particle size D ₅₀ 30 μm), lignite (bulk specific gravity 510 kg / m ³ , specific surface area (BET) 600 m ² / g , Particle size D ₅₀ 25 μm), coconut shell charcoal (bulk specific gravity 510 kg / m ³ , specific surface area 1150 m ² / g), bituminous coal (bulk specific gravity 420 kg / m ³ , specific surface area (BET) 1300 m ² / g, particle size D ₅₀ 15 μm).

得られたスラリーを、１連式濯ぎ装置に送り、スラリーを濯いだ。濯いだスラリーを再度この濯ぎ装置に送り、もう一度濯いで、微粒子と土砂粒子とに分離し、微粒子を懸濁水として除去した（１次濯ぎ）。この１次濯ぎ後の土砂粒子中のダイオキシン類濃度を上記と同様にして分析した。この分析値及び分析箇所を、表２及び図５中でＩＩと表記する。 The resulting slurry was sent to a single rinsing device to rinse the slurry. The rinsed slurry was again sent to the rinsing apparatus and rinsed again to separate the fine particles and earth and sand particles, and the fine particles were removed as suspended water (primary rinse). The concentration of dioxins in the sediment particles after the first rinse was analyzed in the same manner as described above. This analysis value and analysis location are denoted by II in Table 2 and FIG.

次いで、１次濯ぎ後の土砂粒子を、擦りもみ装置で１５分擦りもみを行った後、上記濯ぎ装置に送り、３回濯ぎを繰り返して、微粒子と土砂粒子とに分離し、微粒子を懸濁水として除去した（２次濯ぎ）。この２次濯ぎ後の土砂粒子中のダイオキシン類濃度を上記と同様にして分析した。この分析値及び分析箇所を、表２及び図５中でＩＩＩと表記する。 Next, the sand particles after the first rinsing are rubbed with a rubbed device for 15 minutes, and then sent to the rinsing device, and the rinsing is repeated three times to separate into fine particles and landslide particles. (Second rinse). The concentration of dioxins in the earth and sand particles after the second rinse was analyzed in the same manner as described above. This analysis value and analysis location are denoted as III in Table 2 and FIG.

次いで、ＩＩＩで測定後の土砂粒子を再度擦りもみ装置に戻し、粉末活性炭を０．５質量％添加して１５分擦りもみを行った後、吸着反応タンクで３０分攪拌した。その後、上記濯ぎ装置に送り、３回濯ぎを繰り返して、微粒子と土砂粒子とに分離し、微粒子を懸濁水として除去した（２次濯ぎ）。この２次濯ぎ後の土砂粒子中のダイオキシン類濃度を上記と同様にして分析した。この分析値及び分析箇所を、表２及び図５中でＩＶと表記する。 Next, the earth and sand particles measured in III were returned to the scrubbing apparatus again, 0.5% by mass of powdered activated carbon was added and scrubbing for 15 minutes, and then the mixture was stirred in the adsorption reaction tank for 30 minutes. Thereafter, the rinsing apparatus was sent to the rinsing apparatus, and the rinsing was repeated three times to separate the fine particles and the earth and sand particles, and the fine particles were removed as suspended water (secondary rinsing). The concentration of dioxins in the earth and sand particles after the second rinse was analyzed in the same manner as described above. This analysis value and analysis location are denoted as IV in Table 2 and FIG.

一方、懸濁水については、濃度調整タンクで濃度を調整した後、濁水処理装置に送り、凝集剤として、ポリ塩化アルミニウム（ＰＡＣ）を２０００ｐｐｍ添加し、さらに高分子凝集剤を５ｐｐｍ添加して、凝集分離濃縮し、フロックと分離水とに分離した。分離水はバッファータンクに貯蔵して、スラリー化用水、濯ぎ用水、擦りもみ用水等の再利用に供した。フロックはフィルタープレスに送り、脱水処理し、有害物質の濃縮した微細土粒子と分離水とに分離した。この洗浄濁水の凝集脱水ケーキ（微細土粒子）のダイオキシン類濃度を上記と同様にして分析した。この分析値及び分析箇所を、表２及び図５中でＶと表記する。また、分離水はバッファータンクに貯蔵して、再利用に供した。このバッファータンク内の洗浄濁水の凝集分離水のダイオキシン類濃度は、ＪＩＳＫ０３１２（１９９９）の「工業用水・工場排水中のダイオキシン類及びコプラナーＰＣＢの測定方法」にしたがって、公定法で測定した。この分析値及び分析箇所を、表２及び図５中でＶＩと表記する。 On the other hand, for suspended water, after adjusting the concentration in the concentration adjusting tank, it is sent to a turbid water treatment device, and 2000 ppm of polyaluminum chloride (PAC) is added as a flocculant, and further 5 ppm of a polymer flocculant is added to agglomerate. Separated and concentrated to separate into floc and separated water. The separated water was stored in a buffer tank and reused for slurrying water, rinsing water, rubbing water, and the like. The floc was sent to a filter press, dehydrated, and separated into fine soil particles enriched with harmful substances and separated water. The concentration of dioxins in this washed muddy water agglomerated dehydrated cake (fine soil particles) was analyzed in the same manner as described above. This analysis value and analysis location are denoted as V in Table 2 and FIG. Separated water was stored in a buffer tank for reuse. The concentration of dioxins in the coagulated and separated water of the washed turbid water in the buffer tank was measured by an official method according to “Measurement method of dioxins and coplanar PCB in industrial water and industrial wastewater” of JIS K0312 (1999). This analysis value and analysis location are denoted by VI in Table 2 and FIG.

表１の結果によれば、Ｉの元土壌中のダイオキシン類濃度は１２００〜１３０００ｐｇ−ＴＥＱ／ｇと、土壌環境基準値を大きく上回る値であったが、ＩＩの１次濯ぎ、ＩＩＩの擦りもみ及び２次濯ぎで、一部の試料は基準値以下まで低減し、ＩＶの繰り返し洗浄を行うことにより、すべての試料で基準値の１０００ｐｇ−ＴＥＱ／ｇ以下まで低減した。
また、ＶＩの洗浄濁水の凝集分離水のダイオキシン類濃度は、５．１ｐｇ−ＴＥＱ／Ｌと水質排水基準値の１０ｐｇ−ＴＥＱ／Ｌ以下であり、分離水からもダイオキシン類が除去されていることがわかった。
また、Ｖの洗浄濁水の凝集脱水ケーキ（微細土粒子）中のダイオキシン類濃度は、１００００〜４６０００ｐｇ−ＴＥＱ／ｇと高く、Ｉの元土壌中に含まれていたダイオキシン類のほとんどが微細土粒子に濃縮され、洗浄土砂と分離水からは除去されていることがわかった。 According to the results of Table 1, the concentration of dioxins in the original soil of I was 1200 to 13000 pg-TEQ / g, which was much higher than the soil environmental standard value, but the primary rinse of II and the scuffing of III And by the second rinsing, some samples were reduced to below the reference value, and by performing repeated washing of IV, all samples were reduced to the reference value of 1000 pg-TEQ / g or less.
In addition, the concentration of dioxins in the agglomerated and separated water of washing turbid water of 5.1 is 5.1 pg-TEQ / L and the water drainage standard value of 10 pg-TEQ / L or less, and dioxins are also removed from the separated water. I understood.
In addition, the concentration of dioxins in the coagulated dewatered cake (fine soil particles) of washing turbid water of V is as high as 10,000 to 46000 pg-TEQ / g, and most of the dioxins contained in the original soil of I are fine soil particles. It was found that it was removed from the washed soil and separated water.

以上の結果から、本発明によれば、有害物質を含有する汚染土壌から有害物質を除去し、洗浄土砂と有害物質の濃縮した微細土粒子とに分離することができ、汚染物質は微細土粒子に濃縮されて、洗浄土砂と分離水からは除去されていることが確認された。 From the above results, according to the present invention, it is possible to remove harmful substances from contaminated soil containing harmful substances and separate them into washed soil and fine soil particles enriched with harmful substances. It was confirmed that it was removed from the washed soil and separated water.

第１の実施形態に係る有害物質を含有する汚染土壌の浄化方法の工程図である。It is process drawing of the purification method of the contaminated soil containing the harmful substance which concerns on 1st Embodiment. 第２の実施形態に係る有害物質を含有する汚染土壌の浄化方法の工程図である。It is process drawing of the purification method of the contaminated soil containing the harmful substance which concerns on 2nd Embodiment. 第３の実施形態に係る有害物質を含有する汚染土壌の浄化方法の工程図である。It is process drawing of the purification method of the contaminated soil containing the harmful substance which concerns on 3rd Embodiment. 第５の実施形態に係る有害物質を含有する汚染土壌の浄化方法の工程図である。It is process drawing of the purification method of the contaminated soil containing the harmful substance which concerns on 5th Embodiment. 実施例において、試料を採取し、ダイオキシン類の分析を行った工程箇所をＩ〜ＶＩで表記した汚染土壌の浄化方法の工程図である。In an Example, it is process drawing of the purification method of the contaminated soil which sampled the sample and described the process location which performed the analysis of dioxins by I-VI.

Explanation of symbols

Ａ−１スラリー化混合工程
Ａ−２第１濯ぎ工程
Ａ−３、Ａ−６判定工程
Ａ−４擦りもみ工程
Ａ−５第２濯ぎ工程
Ａ−７吸着攪拌工程
Ａ−８異物除去工程
Ｂ−１凝集濃縮工程
Ｂ−２脱水処理工程

A-1 Slurry-mixing process A-2 First rinsing process A-3, A-6 Judgment process A-4 Scrubbing process A-5 Second rinsing process A-7 Adsorption and stirring process A-8 Foreign matter removing process B- 1 Aggregation and concentration process B-2 Dehydration process

Claims

Removes harmful substances from contaminated soil containing harmful substances, separates them into washed soil and fine soil particles enriched with harmful substances, recycles the washed soil, and collects and processes fine soil particles enriched with harmful substances A method for purifying contaminated soil,
Adding and mixing water and additives to the contaminated soil containing the harmful substances to form a slurry (A-1);
A first rinsing step (A-2) in which the slurry is rinsed and separated into suspended water containing fine soil particles having a particle diameter of 75 μm or less and earth and sand particles having a particle diameter of more than 75 μm ;
And (A-3) determining a contamination level of the separated earth and sand particles ,
And the soil particles and wash sediment condition that the contamination level by the judgment at the step (A-3) is equal to or less than the reference value based regeneration,
50-5000 ppm of a flocculant is added to the suspended water containing fine soil particles separated in the step (A-2), and the suspended water is agglomerated, separated and concentrated to separate the flocs that are aggregates of the fine soil particles. A step (B-1) of separating into water ;
Contaminated soil containing harmful substances, characterized in that the flocs are dehydrated and separated into fine soil particles and separated water (B-2) to obtain fine soil particles enriched with the harmful substances. Purification method.

In the step (A-3), if the contamination level is higher than the reference value, the step of fir rubbing the sand particles (A-4), rinse the soil particles after the rubbing massaging, fine soil particles A second rinsing step (A-5) for separating the suspended water and the earth and sand particles to be contained, and a step (A-6) for re-determining the contamination level of the separated earth and sand particles. -6) The soil particles are recycled as washing soil on condition that the contamination level is below the reference value by the judgment in -6)
Containing toxic substances according to claim 1 to agglomerate separated concentrate with an aqueous suspension containing the step (A-5) separating the water suspension containing the separated fine soil particles in the step (A-2) with fine soil particles To clean up contaminated soil.

Wherein the step (A-4), and a step of fir rubbed by adding an additive to the soil particles (A-4 '), sends the soil particles after the rubbing massaging the adsorption reactor, the step of stirring (A The method for purifying contaminated soil containing harmful substances according to claim 2, which is -7).

Removes harmful substances from contaminated soil containing harmful substances, separates them into washed soil and fine soil particles enriched with harmful substances, recycles the washed soil, and collects and processes fine soil particles enriched with harmful substances A method for purifying contaminated soil,
Adding and mixing water and additives to the contaminated soil containing the harmful substances to form a slurry (A-1);
A first rinsing step (A-2) in which the slurry is rinsed and separated into suspended water containing fine soil particles having a particle diameter of 75 μm or less and earth and sand particles having a particle diameter of more than 75 μm ;
A step (A-3) of determining a contamination level of the separated earth and sand particles ;
In the step (A-3), if the contamination level exceeds the reference value, the earth and sand particles are selected to remove foreign matters (A-8),
A step (A-4) of rubbing the earth and sand particles after removing the foreign matter;
A second rinsing step (A-5) for rinsing the soil particles after scrubbing and separating them into suspended water containing fine soil particles and soil particles ;
And re-determining the contamination level of the separated earth and sand particles (A-6),
The soil particles are recycled as washing soil on the condition that the contamination level is below the reference value by the determination in the step (A-6) ,
50 to 5000 ppm of a flocculant is added to the suspension water separated in the step (A-5) and the suspension water separated in the step (A-2), and the suspension water is agglomerated, separated and concentrated, and the fine soil particles A step (B-1) for separating the floc and the separated water , which are aggregates of
Contaminated soil containing harmful substances, characterized in that the flocs are dehydrated and separated into fine soil particles and separated water (B-2) to obtain fine soil particles enriched with the harmful substances. Purification method.

Removes harmful substances from contaminated soil containing harmful substances, separates them into washed soil and fine soil particles enriched with harmful substances, recycles the washed soil, and collects and processes fine soil particles enriched with harmful substances A method for purifying contaminated soil,
Adding and mixing water and additives to the contaminated soil containing the harmful substances to form a slurry (A-1);
A first rinsing step (A-2) in which the slurry is rinsed and separated into suspended water containing fine soil particles having a particle diameter of 75 μm or less and earth and sand particles having a particle diameter of more than 75 μm ;
A step (A-3) of determining a contamination level of the separated earth and sand particles ;
In the step (A-3), if the contamination level exceeds the reference value, the earth and sand particles are selected to remove foreign matters (A-8),
A step (A-4 ′) of adding an additive to the earth and sand particles after removing the foreign matters and rubbing them;
A step (A-7) of sending and stirring the sand particles after the rubbing to the adsorption reaction tank;
A second rinsing step (A-5) for rinsing the soil particles after scrubbing and separating them into suspended water containing fine soil particles and soil particles ;
And re-determining the contamination level of the separated earth and sand particles (A-6),
The soil particles are recycled as washing soil on the condition that the contamination level is below the reference value by the determination in the step (A-6) ,
50 to 5000 ppm of a flocculant is added to the suspension water separated in the step (A-5) and the suspension water separated in the step (A-2), and the suspension water is agglomerated, separated and concentrated, and the fine soil particles A step (B-1) for separating the floc and the separated water , which are aggregates of
Contaminated soil containing harmful substances, characterized in that the flocs are dehydrated and separated into fine soil particles and separated water (B-2) to obtain fine soil particles enriched with the harmful substances. Purification method.

The separated water separated in the step (B-1) and the step (B-2) is at least the step (A-1), the step (A-2), the step (A-4) or the step ( A-4 ') The purification | cleaning method of the contaminated soil containing the hazardous | toxic substance as described in any one of Claims 1-5 reused as water added in either of the said process (A-5) .

The contaminated soil containing the harmful substance according to any one of claims 1 to 6, wherein the additive is at least one activated carbon selected from the group consisting of bamboo charcoal, peat, lignite, coconut shell charcoal, and bituminous coal. Purification method.