JP2016222776A - Heavy metal insolubilized composition and method for repairing heavy metal contaminated soil - Google Patents
Heavy metal insolubilized composition and method for repairing heavy metal contaminated soil Download PDFInfo
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- 239000000203 mixture Substances 0.000 title claims abstract description 187
- 229910001385 heavy metal Inorganic materials 0.000 title claims abstract description 95
- 238000000034 method Methods 0.000 title abstract description 65
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 93
- -1 iron ions Chemical class 0.000 claims abstract description 93
- 229910052742 iron Inorganic materials 0.000 claims abstract description 92
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 4
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- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 description 3
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- 241000193830 Bacillus <bacterium> Species 0.000 description 2
- 241000894006 Bacteria Species 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
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- PAWQVTBBRAZDMG-UHFFFAOYSA-N 2-(3-bromo-2-fluorophenyl)acetic acid Chemical compound OC(=O)CC1=CC=CC(Br)=C1F PAWQVTBBRAZDMG-UHFFFAOYSA-N 0.000 description 1
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- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 239000001888 Peptone Substances 0.000 description 1
- 108010080698 Peptones Proteins 0.000 description 1
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 description 1
- 244000061456 Solanum tuberosum Species 0.000 description 1
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- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 description 1
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- 230000001133 acceleration Effects 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 1
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 1
- 235000011130 ammonium sulphate Nutrition 0.000 description 1
- 238000003321 atomic absorption spectrophotometry Methods 0.000 description 1
- PLKYGPRDCKGEJH-UHFFFAOYSA-N azane;2-hydroxypropane-1,2,3-tricarboxylic acid;iron Chemical compound N.[Fe].OC(=O)CC(O)(C(O)=O)CC(O)=O PLKYGPRDCKGEJH-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
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- 239000006172 buffering agent Substances 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 235000013877 carbamide Nutrition 0.000 description 1
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- 230000003197 catalytic effect Effects 0.000 description 1
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- 238000009472 formulation Methods 0.000 description 1
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- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 150000002505 iron Chemical class 0.000 description 1
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical class Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 description 1
- 159000000014 iron salts Chemical class 0.000 description 1
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 1
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 1
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 1
- NPFOYSMITVOQOS-UHFFFAOYSA-K iron(III) citrate Chemical compound [Fe+3].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NPFOYSMITVOQOS-UHFFFAOYSA-K 0.000 description 1
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 1
- VRIVJOXICYMTAG-IYEMJOQQSA-L iron(ii) gluconate Chemical compound [Fe+2].OC[C@@H](O)[C@@H](O)[C@H](O)[C@@H](O)C([O-])=O.OC[C@@H](O)[C@@H](O)[C@H](O)[C@@H](O)C([O-])=O VRIVJOXICYMTAG-IYEMJOQQSA-L 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
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- 235000021317 phosphate Nutrition 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
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- 238000000967 suction filtration Methods 0.000 description 1
- JHYAVWJELFKHLM-UHFFFAOYSA-H tetrasodium;2-hydroxypropane-1,2,3-tricarboxylate;iron(2+) Chemical compound [Na+].[Na+].[Na+].[Na+].[Fe+2].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O.[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O JHYAVWJELFKHLM-UHFFFAOYSA-H 0.000 description 1
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Landscapes
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
- Processing Of Solid Wastes (AREA)
- Soil Conditioners And Soil-Stabilizing Materials (AREA)
Abstract
Description
本発明は、重金属不溶化処理組成物及び重金属汚染土壌の修復方法に関する。 The present invention relates to a heavy metal insolubilizing composition and a method for repairing heavy metal contaminated soil.
従来、重金属で汚染された土壌を修復するためには、汚染土壌を掘削除去した後、新たな土壌を供給する方法が知られている。しかしこの方法では、除去した汚染土壌の処理が必要となり、原位置にて汚染土壌を修復する方法が望まれている。
重金属で汚染された土壌の無害化には重金属を不溶化させ、土壌中に流出、拡散することを抑制することが好ましい。代表的な方法としては、重金属汚染土壌に、マグネシウム系固化材、天然鉱物系の吸着材などの不溶化剤を大型機械で注入するか、或いは、土壌と撹拌混合させ、重金属を不溶化する方法が挙げられる。
Conventionally, in order to repair soil contaminated with heavy metals, a method of supplying new soil after excavating and removing the contaminated soil is known. However, this method requires treatment of the removed contaminated soil, and a method for repairing the contaminated soil in situ is desired.
In order to detoxify the soil contaminated with heavy metals, it is preferable to insolubilize heavy metals and to prevent outflow and diffusion into the soil. Typical methods include injecting insolubilizing agents such as magnesium-based solidified materials and natural mineral-based adsorbents into heavy metal-contaminated soil with a large machine, or stirring and mixing with soil to insolubilize heavy metals. It is done.
地盤改良、有害物質の不動化等を目的とした、酸耐性、圧縮強度に優れた炭酸塩を生成しうる技術として、特定のウレアーゼ生成微生物と、尿素と、カルシウムイオンと、第２の金属塩とを特定量含有する反応液を用いて、地盤中に炭酸塩を生成させるセメント工法が提案されている（例えば、特許文献１参照）。
また、金属を含む土壌に対し、セメント由来のカルシウムイオンと、好ましくはさらに硫酸の鉄塩に由来する硫酸イオンとを添加する土壌処理方法が提案されている（例えば、特許文献２参照）。特許文献２に記載の土壌処理方法では、好ましい態様として土壌に注入する組成物に硫酸イオンを含有させることで、主成分であるセメントによる土壌のアルカリ化を抑制することを特徴の一つとしている。
一方、汚染土壌に関する技術ではないが、地盤を硬化させる地盤改良技術として、ウレアーゼの水溶液である第１溶液と、尿素及びカルシウム塩の水溶液である第２溶液とをそれぞれ地盤中に注入し、或いは、上記第１溶液と上記第２溶液とを混合した直後に混合物を地盤中に注入する地盤改良方法が提案されている（例えば、特許文献３参照）。
Specific urease-producing microorganisms, urea, calcium ions, and second metal salts are technologies that can produce carbonates with excellent acid resistance and compressive strength for the purpose of ground improvement and immobilization of harmful substances. There has been proposed a cement construction method in which a carbonate is generated in the ground using a reaction solution containing a specific amount of (see, for example, Patent Document 1).
In addition, a soil treatment method has been proposed in which calcium ions derived from cement and preferably sulfate ions derived from an iron salt of sulfuric acid are added to soil containing metal (for example, see Patent Document 2). One of the features of the soil treatment method described in Patent Document 2 is that, as a preferred embodiment, the composition injected into the soil contains sulfate ions to suppress alkalinization of the soil with cement as a main component. .
On the other hand, although it is not a technique related to contaminated soil, as a ground improvement technique for hardening the ground, a first solution that is an aqueous solution of urease and a second solution that is an aqueous solution of urea and calcium salt are respectively injected into the ground, or There has been proposed a ground improvement method in which the mixture is injected into the ground immediately after the first solution and the second solution are mixed (see, for example, Patent Document 3).
しかしながら、特許文献１に記載されるセメント工法では、ウレアーゼ生成微生物として特殊な微生物を使用する必要があり、微生物の入手が困難であること、セメント工法に使用される組成物の粘度が高いこと、地盤の硬化による地盤改良には、ある程度有効ではあるものの、重金属を不溶化させ、無害化させる効果は不十分であること等の問題があった。
特許文献２に記載の技術では、セメントスラリーに好ましくは硫酸イオンを混合し、土壌中にポンプで圧送して、機械混合し、土壌とセメントスラリーとを均一に混合することで、経時によりセメントスラリー中に含まれるセメントが硬化して、強度が改良された地盤改良体が形成される深層混合処理工法（ＤＣＭ工法）に使用することを前提としており、セメントスラリーの流動性が低く、そのまま土壌に注入して浸透させる方法には適用が困難である。
また、特許文献３に記載の技術は、そもそも、地盤を強化する地盤改良方法に関し、地盤の液状化抑制等には有効であるものの、土壌中の重金属を無害化させることについては全く考慮されていない。
However, in the cement method described in Patent Document 1, it is necessary to use a special microorganism as a urease-producing microorganism, and it is difficult to obtain the microorganism, the viscosity of the composition used in the cement method is high, Although it is effective to some extent for ground improvement by hardening of the ground, there are problems such as insufficient effect of insolubilizing and detoxifying heavy metals.
In the technique described in Patent Document 2, sulfate ions are preferably mixed with cement slurry, pumped into the soil with a pump, mechanically mixed, and the soil and cement slurry are uniformly mixed. It is assumed that it will be used in the deep mixing method (DCM method) in which the cement contained in it is hardened and a ground improvement body with improved strength is formed. It is difficult to apply to the method of injection and penetration.
In addition, the technique described in Patent Document 3 relates to a ground improvement method for strengthening the ground in the first place, but it is completely considered for detoxifying heavy metals in soil, although it is effective for suppressing liquefaction of the ground. Absent.
本発明の課題は、流動性が高く、土壌への浸透性が良好であり、重金属の不溶化効果に優れた重金属不溶化処理組成物を提供することにある。
本発明の別の課題は、重金属汚染土壌における重金属の不溶化効果に優れ、重金属汚染土壌を原位置で簡易に処理することができる重金属汚染土壌の修復方法を提供することにある。
An object of the present invention is to provide a heavy metal insolubilization composition having high fluidity, good soil permeability, and excellent heavy metal insolubilization effect.
Another object of the present invention is to provide a method for repairing heavy metal-contaminated soil, which is excellent in insolubilizing heavy metal in heavy metal-contaminated soil and can be easily treated in situ.
本発明者は鋭意検討の結果、ウレアーゼ生成微生物と、尿素と、カルシウムイオンと、鉄イオンと、を含む組成物において、カルシウムイオンと、鉄イオンとの配合比率、含有量を適切な範囲に制御することで、土壌中の重金属の固定化効果が向上することを見出し、本発明を完成した。
本発明は、以下の実施形態を含む。
As a result of intensive studies, the present inventor has controlled the blending ratio and content of calcium ions and iron ions in an appropriate range in a composition containing urease-producing microorganisms, urea, calcium ions, and iron ions. As a result, it was found that the effect of immobilizing heavy metals in soil was improved, and the present invention was completed.
The present invention includes the following embodiments.
＜１＞ ウレアーゼ生成微生物と、尿素と、カルシウムイオンと、鉄イオンと、を含み、前記カルシウムイオンの含有量をＡ（ｍｇ／Ｌ）とし、前記鉄イオンの含有量をＢ（ｍｇ／Ｌ）としたとき、ＡとＢとの関係が、下記式（１）、下記式（２）及び下記式（３）の条件を満たす、重金属不溶化処理組成物である。
式（１）：２／１≦Ａ／Ｂ≦２０／１（質量基準）
式（２）：５４ｍｇ／Ｌ≦Ａ≦３０００ｍｇ／Ｌ
式（３）：１５ｍｇ／Ｌ≦Ｂ≦３００ｍｇ／Ｌ
<1> A urease-producing microorganism, urea, calcium ions, and iron ions, wherein the content of calcium ions is A (mg / L), and the content of iron ions is B (mg / L) The heavy metal insolubilized composition in which the relationship between A and B satisfies the conditions of the following formula (1), the following formula (2), and the following formula (3).
Formula (1): 2/1 ≦ A / B ≦ 20/1 (mass basis)
Formula (2): 54 mg / L ≦ A ≦ 3000 mg / L
Formula (3): 15 mg / L ≦ B ≦ 300 mg / L
本実施形態によれば、重金属不溶化処理組成物(以下、単に「不溶化処理組成物」と称することがある）は、尿素と、ウレアーゼ生成微生物と、カルシウムイオンと、前記カルシウムイオンの含有量よりも低い特定の含有比率の鉄イオンと、を含有し、かつ、カルシウムイオンと鉄イオンとの総含有量が少ない。このため、不溶化処理組成物は流動性に優れ、土壌中に速やかに浸透する。その後、浸透した土壌内において、ウレアーゼ生成微生物が尿素に作用して尿素が分解し、生成される炭酸イオンとカルシウムイオンとが反応して硬質の炭酸カルシウムが析出する。さらに共存する鉄イオンによる、水酸化鉄も生成され、カルシウムイオンと鉄イオンの共存により、炭酸カルシウム中に重金属が効率よく取り込まれて不溶化し、かつ、生成された炭酸カルシウムの表面において、鉄イオンの存在に起因して重金属が鉄イオンに吸着され、炭酸カルシウムの表面に固定化される。
このため、土壌への注入時には不溶化処理組成物の流動性が良好であり、土壌に効率よく浸透、拡散し、土壌中における反応により固形物である炭酸カルシウム等が析出して重金属を不溶化させるため、土壌中の重金属の不溶化処理効率に優れるものと考えられる。
なお、不溶化処理組成物は、土壌に注入すると、土壌、特に飽和帯水層における土壌粒子の間隙中に存在する間隙水により希釈される。以下に詳述するように、本発明の不溶化処理組成物における有効成分の含有量は、土壌中において間隙水により希釈された後に良好な効果を発現する濃度を勘案して定められている。
According to the present embodiment, the heavy metal insolubilization treatment composition (hereinafter sometimes simply referred to as “insolubilization treatment composition”) is more than urea, urease-producing microorganisms, calcium ions, and the content of the calcium ions. It contains a low specific content ratio of iron ions, and the total content of calcium ions and iron ions is small. For this reason, the insolubilization processing composition is excellent in fluidity | liquidity, and osmose | permeates rapidly in soil. Thereafter, in the permeated soil, urease-producing microorganisms act on urea to decompose urea, and the produced carbonate ions and calcium ions react to precipitate hard calcium carbonate. Furthermore, iron hydroxide is also generated by the coexisting iron ions, and by coexistence of calcium ions and iron ions, heavy metals are efficiently incorporated into calcium carbonate and insolubilized, and iron ions are formed on the surface of the generated calcium carbonate. Because of the presence of heavy metals, heavy metals are adsorbed on iron ions and immobilized on the surface of calcium carbonate.
For this reason, the fluidity of the insolubilized composition is good when injected into the soil, and it penetrates and diffuses efficiently into the soil, so that calcium carbonate, which is a solid substance, precipitates due to the reaction in the soil and insolubilizes heavy metals. It is considered that the insolubilization efficiency of heavy metals in the soil is excellent.
In addition, when the insolubilized composition is injected into the soil, it is diluted with pore water present in the pores of the soil particles in the soil, particularly in the saturated aquifer. As described in detail below, the content of the active ingredient in the insolubilized composition of the present invention is determined in consideration of the concentration at which a good effect is exhibited after dilution with pore water in soil.
＜２＞ ２５℃における粘度が、１×１０−３Ｐａ・ｓ〜１．５×１０−３Ｐａ・ｓである、＜１＞に記載の重金属不溶化処理組成物である。
本実施形態によれば、不溶化処理組成物の粘度を上記範囲とすることで、流動性がより良好となり、オーガーなどの掘削装置、機械的撹拌装置等を使用しなくても、不溶化処理組成物の汚染土壌中への浸透、拡散が速やかに行なわれ、土壌中の重金属の不溶化がより効率よく行なわれる。
<2> The heavy metal insolubilized composition according to <1>, wherein the viscosity at 25 ° C. is 1 × 10 −3 Pa · s to 1.5 × 10 −3 Pa · s.
According to this embodiment, by making the viscosity of the insolubilizing treatment composition within the above range, the fluidity becomes better, and the insolubilizing treatment composition can be used without using an excavator such as an auger or a mechanical stirring device. Infiltration and diffusion into the contaminated soil are carried out quickly, and insolubilization of heavy metals in the soil is performed more efficiently.
＜３＞ ウレアーゼ生成微生物と、尿素と、カルシウムイオンと、鉄イオンと、を含み、前記カルシウムイオンの含有量をＡ（ｍｇ／Ｌ）とし、前記鉄イオンの含有量をＢ（ｍｇ／Ｌ）としたとき、ＡとＢとの関係が、下記式（１）、下記式（２）及び下記式（３）の条件を満たす重金属不溶化処理組成物を処理対象土壌に注入することを含む、重金属汚染土壌の修復方法。
式（１）：２／１≦Ａ／Ｂ≦２０／１（質量基準）
式（２）：５４ｍｇ／Ｌ≦Ａ≦３０００ｍｇ／Ｌ
式（３）：１５ｍｇ／Ｌ≦Ｂ≦３００ｍｇ／Ｌ
本実施形態によれば、不溶化処理組成物が速やかに重金属汚染土壌中に浸透する。不溶化処理組成物が、尿素と、ウレアーゼ生成微生物とを含有することで、土壌に注入された不溶化処理組成物に含まれるウレアーゼ生成微生物が尿素に作用して尿素の分解を促進させ、その結果生成される炭酸イオンとカルシウムイオンとが反応して土壌内において硬質の炭酸カルシウムが析出する。このとき、カルシウムイオンに対し、カルシウムイオンの含有量よりも低い特定の含有比率の鉄イオンが存在することで、鉄イオンに吸着した重金属が、析出した炭酸カルシウムに効率よく取り込まれて不溶化される。また、鉄イオン自体も水酸化鉄を形成し、さらに、析出した炭酸カルシウム表面においても、鉄イオンが重金属を吸着して固定化するために、土壌中の重金属が効率よく不溶化される。なお、浸透した不溶化処理組成物は、土壌中の間隙水により希釈され、不溶化処理組成物におけるカルシウムイオン濃度及び鉄イオン濃度が、重金属の不溶化がより効果的に行なわれる値に調整される。このため、本発明の重金属汚染土壌の修復方法によれば、効率よく重金属が不溶化されることで土壌に対する重金属の影響が低減され、原位置において重金属汚染土壌の修復が効率よく行なわれる。
<3> A urease-producing microorganism, urea, calcium ions, and iron ions, wherein the content of the calcium ions is A (mg / L), and the content of the iron ions is B (mg / L) When the heavy metal insolubilized composition that satisfies the conditions of the following formula (1), the following formula (2), and the following formula (3) is injected into the soil to be treated, How to repair contaminated soil.
Formula (1): 2/1 ≦ A / B ≦ 20/1 (mass basis)
Formula (2): 54 mg / L ≦ A ≦ 3000 mg / L
Formula (3): 15 mg / L ≦ B ≦ 300 mg / L
According to this embodiment, the insolubilized composition quickly penetrates into the heavy metal contaminated soil. Since the insolubilized composition contains urea and urease-producing microorganisms, the urease-producing microorganisms contained in the insolubilized composition injected into the soil act on urea to accelerate the decomposition of urea, and as a result The carbonate ions and calcium ions react to form hard calcium carbonate in the soil. At this time, the presence of iron ions having a specific content ratio lower than the calcium ion content with respect to the calcium ions allows heavy metals adsorbed to the iron ions to be efficiently incorporated into the precipitated calcium carbonate and insolubilized. . In addition, iron ions themselves form iron hydroxide, and the iron ions adsorb and immobilize heavy metals on the precipitated calcium carbonate surface, so that heavy metals in the soil are efficiently insolubilized. The infiltrated insolubilized composition is diluted with pore water in the soil, and the calcium ion concentration and the iron ion concentration in the insolubilized composition are adjusted to values at which heavy metals are insolubilized more effectively. Therefore, according to the method for repairing heavy metal-contaminated soil of the present invention, the heavy metal is insolubilized efficiently, so that the influence of heavy metal on the soil is reduced, and the heavy metal-contaminated soil is efficiently repaired in situ.
＜４＞ 前記重金属不溶化処理組成物を処理対象土壌に注入することが、注入井戸を用いて行なわれ、さらに注入された重金属不溶化処理組成物を、吸入井戸を用いて回収することを含む、＜３＞に記載の重金属汚染土壌の修復方法。
本実施形態によれば、不溶化処理組成物の流動性が良好であるために、土壌への浸透、拡散が効率よく行なわれ、さらに、土壌中における間隙水により希釈された不溶化処理組成物はより流動性が向上するために、オーガー等の掘削装置を用いることなく、注入井戸と吸入井戸とを用いて重金属汚染土壌の修復を行なうことができ、原位置における重金属汚染土壌の修復をより簡易に行なうことができる。
<4> Injecting the heavy metal insolubilization treatment composition into the soil to be treated is performed using an injection well, and further includes recovering the injected heavy metal insolubilization treatment composition using an intake well. The method for repairing heavy metal-contaminated soil according to 3>.
According to this embodiment, since the fluidity of the insolubilized treatment composition is good, the infiltration and diffusion into the soil is efficiently performed, and the insolubilized treatment composition diluted with pore water in the soil is more Because of improved fluidity, it is possible to repair heavy metal contaminated soil using an injection well and a suction well without using an excavator such as an auger, making it easier to repair heavy metal contaminated soil in situ. Can be done.
本発明によれば、流動性が高く、土壌への浸透性が良好であり、重金属の不溶化効果に優れた重金属不溶化処理組成物を提供することができる。
また、本発明によれば、重金属汚染土壌における重金属の不溶化効果に優れ、重金属汚染土壌を原位置で簡易に処理することができる重金属汚染土壌の修復方法を提供することができる。
According to the present invention, it is possible to provide a heavy metal insolubilized composition having high fluidity, good soil permeability, and excellent heavy metal insolubilization effect.
Moreover, according to this invention, it is excellent in the insolubilization effect of the heavy metal in heavy metal-contaminated soil, and can provide the repair method of heavy metal-contaminated soil which can process a heavy metal-contaminated soil simply in-situ.
＜重金属不溶化処理組成物＞
本発明の重金属不溶化処理組成物は、ウレアーゼ生成微生物と、尿素と、カルシウムイオンと、鉄イオンと、を含み、前記カルシウムイオンの含有量をＡ（ｍｇ／Ｌ）とし、前記鉄イオンの含有量をＢ（ｍｇ／Ｌ）としたとき、ＡとＢとの関係が、下記式（１）、下記式（２）及び下記式（３）の条件を満たす重金属不溶化処理組成物である。
式（１）：２／１≦Ａ／Ｂ≦２０／１（質量基準）
式（２）：５４ｍｇ／Ｌ≦Ａ≦３０００ｍｇ／Ｌ
式（３）：１５ｍｇ／Ｌ≦Ｂ≦３００ｍｇ／Ｌ
このような不溶化処理組成物を土壌中に浸透させることで、土壌中において不溶化処理組成物が土壌中の間隙水により希釈されて、不溶化処理組成物に含まれる有効成分が適切な濃度に調整される。希釈された不溶化処理組成物に含まれるウレアーゼ生成微生物が生成するウレアーゼにより尿素が分解して発生した炭酸イオンとカルシウムイオンとが反応して炭酸カルシウムが析出する。
<Heavy metal insolubilization composition>
The heavy metal insolubilization treatment composition of the present invention comprises a urease-producing microorganism, urea, calcium ions, and iron ions, and the content of the calcium ions is A (mg / L), and the content of the iron ions Is a heavy metal insolubilized composition in which the relationship between A and B satisfies the conditions of the following formula (1), the following formula (2) and the following formula (3).
Formula (1): 2/1 ≦ A / B ≦ 20/1 (mass basis)
Formula (2): 54 mg / L ≦ A ≦ 3000 mg / L
Formula (3): 15 mg / L ≦ B ≦ 300 mg / L
By infiltrating such insolubilized composition into the soil, the insolubilized composition is diluted in the soil with pore water in the soil, and the active ingredient contained in the insolubilized composition is adjusted to an appropriate concentration. The The carbonate ions generated by the decomposition of urea by the urease produced by the urease-producing microorganisms contained in the diluted insolubilized composition react with calcium ions to precipitate calcium carbonate.
（ウレアーゼ生成微生物）
本発明の不溶化処理組成物は、ウレアーゼ生成微生物を含有する。
ウレアーゼ生成微生物とは、ウレアーゼを生成し、生成されたウレアーゼの触媒作用により尿素を分解して炭酸イオンを生成させる微生物を指す。
ウレアーゼ生成微生物としては、特に限定はなく、例えば、バチルス スポトゥリ、バチルス スポロサルシナ、スポロラクトバチルス、クロストリジウム、デスルホトマキュルムを含む属の一覧から選択される細菌等が挙げられる。本発明におけるウレアーゼ生成微生物は、これらの例に限定されず、多くのウレアーゼを生成し得る微生物を使用することができる。
(Urease-producing microorganism)
The insolubilized composition of the present invention contains a urease-producing microorganism.
The urease-producing microorganism refers to a microorganism that produces urease and decomposes urea to produce carbonate ions by the catalytic action of the produced urease.
The urease-producing microorganism is not particularly limited, and examples thereof include bacteria selected from a list of genera including Bacillus spoturi, Bacillus sporosarsina, Sporolactobacillus, Clostridium, and Desulfotomacrum. The urease producing microorganism in the present invention is not limited to these examples, and microorganisms capable of producing many urease can be used.
なかでも、処理される土壌から採取したウレアーゼ生成微生物を用いることが好ましい。即ち、処理される土壌中からウレアーゼ産出能を有する微生物を抽出し、集積培養により活性を高めたウレアーゼ生成微生物を不溶化処理組成物に用いることで、処理される土壌における生態系等への影響を最小限とすることができる。
ウレアーゼ生成微生物の培養方法としては、例えば、処理される原位置の土壌サンプルより採取したウレアーゼ生成微生物群に対して、栄養塩類及び尿素を添加し培養を行う方法が挙げられる。培養方法として、集積培養法を行なうことで、より効率よくウレアーゼ生成微生物の培養を行なうことができる。集積培養法とは、菌体培養液を遠心分離によりろ液と菌体に分離し、新たな培養液を添加することで集積効率の向上および必要培養期間の短縮を図る培養方法である。集積された菌体を、所定濃度の尿素および栄養塩類を加えた培養液に添加し、約３０℃の温度条件下で静置培養することで、例えば、７日〜１４日間で実際の施工に使用可能な濃度および液量のウレアーゼ生成微生物を得ることができる。
不溶化処理組成物におけるウレアーゼ生成微生物の含有量は、菌体培養液の濃度として、０．３質量％〜１５．０質量％が好ましく、０．６質量％〜６．０質量％がより好ましい。
飽和帯水層における土壌中には、一般的に、土壌１ｍ３当たり、０．２ｍ３前後の間隙水が土壌の間隙に存在する。このため、不溶化処理組成物は土壌中において間隙水によって希釈され、その結果、ウレアーゼ生成微生物の濃度は、注入後の間隙水を勘案すると、土壌中における菌体培養液の濃度として、０．１質量％〜５．０質量％という菌体がウレアーゼを効率よく生成するのに好ましい含有量となり、より好ましい含有量の不溶化処理組成物を用いた場合、間隙水による希釈後には、０．２質量％〜２．０質量％のより好ましい含有量の範囲となる。
Among these, it is preferable to use urease-producing microorganisms collected from the soil to be treated. In other words, by extracting microorganisms capable of producing urease from the treated soil and using the urease-producing microorganisms whose activity has been enhanced by enrichment culture in the insolubilized composition, the effect on the ecosystem in the treated soil is affected. Can be minimal.
Examples of the culture method for urease-producing microorganisms include a method in which nutrient salts and urea are added to a group of urease-producing microorganisms collected from an in situ soil sample to be treated. As an culturing method, urease-producing microorganisms can be cultured more efficiently by performing an accumulation culture method. The enrichment culture method is a culture method that improves the accumulation efficiency and shortens the required culture period by separating the cell culture solution into a filtrate and cells by centrifugation and adding a new culture solution. The accumulated cells are added to a culture solution to which a predetermined concentration of urea and nutrients are added, and then statically cultured at a temperature of about 30 ° C., for example, for actual construction in 7 to 14 days. A urease-producing microorganism having a usable concentration and liquid amount can be obtained.
The content of the urease-producing microorganism in the insolubilized composition is preferably 0.3% by mass to 15.0% by mass, more preferably 0.6% by mass to 6.0% by mass, as the concentration of the bacterial cell culture solution.
The soil in the saturated aquifer, in general, soil 1 m 3 per, 0.2 m 3 before and after the interstitial water is present in the gap soil. Therefore, the insolubilized composition is diluted with pore water in the soil, and as a result, the concentration of urease-producing microorganisms is 0.1% as the concentration of the cell culture solution in the soil, taking into account the pore water after injection. When the insoluble composition having a more preferable content is used, the bacterial cell of mass% to 5.0 mass% has a preferable content for efficiently producing urease, and 0.2 mass after dilution with pore water. It becomes the range of more preferable content of% -2.0 mass%.
（尿素）
本発明の不溶化処理組成物は尿素を含有する。
尿素としては、一般に入手可能な農業用肥料、試薬などを用いることができる。
本発明の不溶化処理組成物に含まれる尿素の含有量は、組成物全量に対して６０ｍｇ／Ｌ〜６０００ｍｇ／Ｌであることが好ましく、２７０ｍｇ／Ｌ〜２７００ｍｇ／Ｌであることがより好ましい。組成物全量に対する尿素の量が上記範囲であると、不溶化処理組成物を土壌に注入した後に、間隙水により希釈された尿素の濃度として、２０ｍｇ／Ｌ〜２０００ｍｇ／Ｌ、より好ましくは、９０ｍｇ／Ｌ〜９００ｍｇ／Ｌの範囲となる。土壌中における尿素の含有量が既述の範囲であることで、ウレアーゼ生成微生物の機能と相俟って土壌中で必要量の炭酸イオンを生成することができる。
尿素は水溶液として不溶化処理組成物に含有させることができる。
尿素は単独で不溶化処理組成物に含有させてもよく、後述するように、尿素と、前記ウレアーゼ生成微生物の生育に必要な栄養塩、炭酸水素ナトリウム、カルシウムイオン源となる塩化カルシウム等を含む固化溶液として含有させてもよい。
(urea)
The insolubilizing treatment composition of the present invention contains urea.
As urea, generally available agricultural fertilizers, reagents and the like can be used.
The content of urea contained in the insolubilized composition of the present invention is preferably 60 mg / L to 6000 mg / L, more preferably 270 mg / L to 2700 mg / L with respect to the total amount of the composition. When the amount of urea relative to the total amount of the composition is in the above range, the concentration of urea diluted with pore water after injection of the insolubilized composition into the soil is 20 mg / L to 2000 mg / L, more preferably 90 mg / L. The range is from L to 900 mg / L. When the urea content in the soil is in the above-described range, a necessary amount of carbonate ion can be generated in the soil in combination with the function of the urease-producing microorganism.
Urea can be included in the insolubilized composition as an aqueous solution.
Urea may be contained alone in the insolubilized composition, and as will be described later, solidified containing urea and nutrient salts necessary for the growth of the urease-producing microorganism, sodium bicarbonate, calcium chloride as a source of calcium ions, and the like. You may make it contain as a solution.
（カルシウムイオン）
本発明の不溶化処理剤はカルシウムイオンを含有する。
一般的には、水中で解離してカルシウムイオンを生成するカルシウムの塩化物、酸化物、水酸化物などのカルシウム塩として不溶化処理組成物に含有させることが好ましく、なかでも、解離し易いこと、入手が容易であることなどの観点から塩化カルシウム等を用いることが好ましい。
カルシウムイオンの含有量は、不溶化処理組成物に対して、前記式（２）に記載の如く５４ｍｇ／Ｌ〜３０００ｍｇ／Ｌの範囲であり、１８０ｍｇ／Ｌ〜１８００ｍｇ／Ｌの範囲であることが好ましく、５４０ｍｇ／Ｌ〜１８００ｍｇ／Ｌの範囲であることがより好ましい。不溶化処理組成物中におけるカルシウムイオンの含有量が上記範囲であることで、不溶化処理組成物を土壌に注入した後、間隙水により希釈された組成物におけるカルシウムイオン含有量として１８ｍｇ／Ｌ〜１０００ｍｇ／Ｌの範囲となり、好ましくは６０ｍｇ／Ｌ〜６００ｍｇ／Ｌの範囲となり、より好ましくは、１８０ｍｇ／Ｌ〜６００ｍｇ／Ｌの範囲となり、土壌中で重金属を効果的に不溶化するための炭酸カルシウムの析出が効率よく行なわれる。
例えば、前記特許文献１に記載のセメント工法では、実際に使用されているカルシウムイオンの含有量は、５００ｍＭ〜１０００ｍＭ、即ち、２０ｇ／Ｌ〜４０ｇ／Ｌであることに比較して、本発明の不溶化処理組成物を用いれば、極めて少量のカルシウムイオンの添加によって効果を奏することが本発明の利点の一つであるといえる。
(Calcium ion)
The insolubilizing agent of the present invention contains calcium ions.
In general, it is preferable to contain calcium salts such as calcium chlorides, oxides, hydroxides, etc. that dissociate in water to produce calcium ions, and in particular, it is easy to dissociate, Calcium chloride or the like is preferably used from the viewpoint of easy availability.
The calcium ion content is in the range of 54 mg / L to 3000 mg / L, preferably in the range of 180 mg / L to 1800 mg / L, as described in the formula (2) with respect to the insolubilized composition. More preferably, it is in the range of 540 mg / L to 1800 mg / L. Since the content of calcium ions in the insolubilized composition is in the above range, the calcium ion content in the composition diluted with pore water after injecting the insolubilized composition into the soil is 18 mg / L to 1000 mg / L, preferably 60 mg / L to 600 mg / L, more preferably 180 mg / L to 600 mg / L, and precipitation of calcium carbonate for effectively insolubilizing heavy metals in the soil. It is done efficiently.
For example, in the cement method described in Patent Document 1, the calcium ion content actually used is 500 mM to 1000 mM, that is, 20 g / L to 40 g / L. If an insolubilized composition is used, it can be said that it is one of the advantages of the present invention that an effect is obtained by adding a very small amount of calcium ions.
（鉄イオン）
本発明の不溶化処理組成物は鉄イオンを含有する。
鉄イオンを不溶化処理組成物に含有させる場合、例えば、鉄イオン溶液として市販されている鉄イオン試薬を用いてもよく、水中で解離して鉄イオンを生成する鉄の塩化物、酸化物、水酸化物などの鉄塩として不溶化処理組成物に含有させてもよい。鉄イオン源としては、例えば、硫酸第一鉄、硫酸第二鉄、塩化第二鉄、クエン酸鉄、クエン酸鉄アンモニウム、クエン酸第一鉄ナトリウム、グルコン酸鉄などが挙げられる。
鉄イオンの含有量は、不溶化処理組成物に対して、前記式（３）に記載の如く１５ｍｇ／Ｌ〜３００ｍｇ／Ｌの範囲であり、３０ｍｇ／Ｌ〜１５０ｍｇ／Ｌの範囲であることが好ましい。不溶化処理組成物中における鉄イオンの含有量が上記範囲であることで、不溶化処理組成物を土壌に注入した後、間隙水により希釈された組成物における鉄イオン含有量として５ｍｇ／Ｌ〜１００ｍｇ／Ｌの範囲となり、より好ましくは１０ｍｇ／Ｌ〜５０ｍｇ／Ｌの範囲となり、土壌中で重金属を効果的に不溶化するための水酸化鉄の析出及び炭酸カルシウム表面における鉄イオンによる重金属の吸着が効率よく行なわれる。
例えば、前記特許文献２に記載の土壌処理方法では、実施例に使用されている鉄イオンの含有量は、土１ｍ３に対して、２３０ｍＭ、即ち、１２．９ｇ／Ｌであり、本発明の不溶化処理組成物における鉄イオンの含有量に対し、約２５０倍〜１０００倍であり、本発明の不溶化処理組成物を用いることで、組成物中における鉄イオンの含有量が極めて少量に抑えられている。
(Iron ion)
The insolubilized composition of the present invention contains iron ions.
When iron ion is contained in the insolubilized composition, for example, an iron ion reagent that is commercially available as an iron ion solution may be used, and iron chlorides, oxides, and water that dissociate in water to produce iron ions. You may make it contain in an insolubilization process composition as iron salts, such as an oxide. Examples of the iron ion source include ferrous sulfate, ferric sulfate, ferric chloride, iron citrate, ammonium iron citrate, sodium ferrous citrate, and iron gluconate.
The content of iron ions is in the range of 15 mg / L to 300 mg / L, preferably in the range of 30 mg / L to 150 mg / L, as described in the formula (3) with respect to the insolubilized composition. . Since the content of iron ions in the insolubilized composition is in the above range, the insolubilized composition is injected into the soil, and then the iron ion content in the composition diluted with pore water is 5 mg / L to 100 mg / L, more preferably in the range of 10 mg / L to 50 mg / L, and precipitation of iron hydroxide to effectively insolubilize heavy metals in the soil and adsorption of heavy metals by iron ions on the surface of calcium carbonate are efficient. Done.
For example, in the soil treatment method described in Patent Document 2, the content of iron ions used in the examples is 230 mM, that is, 12.9 g / L with respect to 1 m 3 of soil. The content of iron ions in the insolubilized composition is about 250 times to 1000 times, and by using the insolubilized composition of the present invention, the content of iron ions in the composition is suppressed to a very small amount. Yes.
カルシウムイオンは、ウレアーゼ生成微生物が生成したウレアーゼ（尿素分解酵素）により尿素が分解されて生成した炭酸イオンと反応し、下記式に記載のような反応により、炭酸カルシウムが土壌中に析出する
ＣＯ（ＮＨ２）２＋２Ｈ２Ｏ → ２ＮＨ４ ＋＋ＣＯ３ ２− （尿素の加水分解）
ＣａＣｌ２ → Ｃａ２＋＋２Ｃｌ− （塩化カルシウムの解離）
Ｃａ２＋＋ＣＯ３ ２− → ＣａＣＯ３ （炭酸カルシウムの析出）
Calcium ions react with carbonate ions produced by the decomposition of urea by urease (urea degrading enzyme) produced by urease-producing microorganisms, and calcium carbonate is precipitated in the soil by the reaction described in the following formula. NH 2 ) 2 + 2H 2 O → 2NH 4 + + CO 3 2− (hydrolysis of urea)
CaCl 2 → Ca 2+ + 2Cl − (dissociation of calcium chloride)
Ca 2+ + CO 3 2− → CaCO 3 (precipitation of calcium carbonate)
また、鉄イオンは、土壌中での水酸化鉄生成反応により、ヒ素溶液中におけるヒ素濃度を低減させる効果が知られているが、本発明者らの検討によれば、鉄イオン単独での重金属の固定化効果は実用上満足できるものではなかった。
しかし、カルシウムイオンに対し、以下に記載する比率と含有量とで、少量の鉄イオンを不溶化処理組成物に含有させることにより、重金属の不溶化効果が著しく向上することを見出した。
In addition, iron ions are known to have an effect of reducing the arsenic concentration in the arsenic solution by an iron hydroxide formation reaction in the soil, but according to the study by the present inventors, heavy metals with iron ions alone are known. The immobilization effect of was not satisfactory in practice.
However, it has been found that the insolubilization effect of heavy metals is remarkably improved by containing a small amount of iron ions in the insolubilized composition at the ratio and content described below with respect to calcium ions.
（カルシウムイオンと鉄イオンの含有量）
本発明においては、カルシウムイオン及び鉄イオンの含有量の比率が重要である。即ち、カルシウムイオンの含有量をＡ（ｍｇ／Ｌ）とし、鉄イオンの含有量をＢ（ｍｇ／Ｌ）としたとき、ＡとＢとの関係が、下記式（１）、下記式（２）及び下記式（３）の条件を満たす。
式（１）：２／１≦Ａ／Ｂ≦２０／１（質量基準）
式（２）：５４ｍｇ／Ｌ≦Ａ≦３０００ｍｇ／Ｌ
式（３）：１５ｍｇ／Ｌ≦Ｂ≦３００ｍｇ／Ｌ
(Content of calcium ion and iron ion)
In the present invention, the ratio of the content of calcium ions and iron ions is important. That is, when the calcium ion content is A (mg / L) and the iron ion content is B (mg / L), the relationship between A and B is expressed by the following formulas (1) and (2). ) And the following equation (3).
Formula (1): 2/1 ≦ A / B ≦ 20/1 (mass basis)
Formula (2): 54 mg / L ≦ A ≦ 3000 mg / L
Formula (3): 15 mg / L ≦ B ≦ 300 mg / L
式(１)の規定によれば、鉄イオンの含有量に対するカルシウムイオンの含有比率は、質量基準で２倍〜２０倍であることを要し、１２倍〜１８倍であることが好ましい。
鉄イオンの含有比率が上記範囲よりも小さい場合、鉄イオンの併用による効果が得難く、鉄イオンの含有比率が上記範囲を超えて大きい場合には、鉄イオンの添加に伴う効果の向上が認められず、却って、不溶化処理組成物の粘度が上昇したり、土壌中に不溶化処理組成物を注入した際に所望されない不溶物の析出が起こりやすくなったりするため、好ましくない。
According to the definition of the formula (1), the content ratio of calcium ions with respect to the content of iron ions needs to be 2 to 20 times on a mass basis, and preferably 12 to 18 times.
When the content ratio of iron ions is smaller than the above range, it is difficult to obtain the effect due to the combined use of iron ions. When the content ratio of iron ions is larger than the above range, the effect accompanying the addition of iron ions is recognized. On the other hand, the viscosity of the insolubilized composition is increased, and when the insolubilized composition is injected into the soil, undesired insoluble matters are likely to be precipitated.
不溶化処理組成物におけるカルシウムイオン及び鉄イオンの含有量は、それぞれ式（２）及び式（３）の規定する範囲である。
また、不溶化処理組成物におけるカルシウムイオン及び鉄イオンの総含有量は、６９ｍｇ／Ｌ以上３３００ｍｇ／Ｌ以下であり、２００ｍｇ／Ｌ以上２０００ｍｇ／Ｌ以下であることが好ましい。
カルシウムイオン及び鉄イオンの総含有量が６９ｍｇ／Ｌ未満である場合、重金属の不溶化効果が不十分となり、３３００ｍｇ／Ｌを超えると不溶化処理組成物の粘度が上昇し、作業性が低下するため、いずれも好ましくない。
The contents of calcium ions and iron ions in the insolubilized composition are the ranges defined by the formula (2) and the formula (3), respectively.
Moreover, the total content of calcium ions and iron ions in the insolubilized composition is 69 mg / L or more and 3300 mg / L or less, and preferably 200 mg / L or more and 2000 mg / L or less.
When the total content of calcium ions and iron ions is less than 69 mg / L, the effect of insolubilizing heavy metals is insufficient, and when it exceeds 3300 mg / L, the viscosity of the insolubilized composition increases and the workability decreases. Neither is preferred.
カルシウムイオン及び鉄イオンを上記含有比率及び含有量で不溶化処理組成物に含有することの作用は明確ではないが、水酸化鉄の生成に伴って鉄イオンに吸着した重金属が、炭酸カルシウムの析出時に炭酸カルシウム内に取り込まれて固定化され、さらに、炭酸カルシウム表面に残存する鉄イオンが重金属を吸着固定化するためと考えられる。カルシウムイオンと鉄イオンとの含有比率が上記範囲であることで、炭酸カルシウムの析出時に固定化される重金属の量が、カルシウムイオン単独による炭酸カルシウムの析出時の重金属の固定化量に比較して、より増大する。また、鉄イオン単独による水酸化鉄形成時の重金属の固定化量を勘案しても、カルシウムイオンと鉄イオンとを併用することで、より効率的な重金属の固定化が行なわれる。このため、カルシウムイオン及び鉄イオンをそれぞれ単独で含有する土壌改良用組成物と比較しても、重金属の固定化効率がより高まったと考えられる。
しかし、本発明は上記推定機構には何ら制限されない。
Although the effect of containing calcium ions and iron ions in the insolubilized composition at the above content ratio and content is not clear, heavy metal adsorbed on iron ions with the formation of iron hydroxide is It is considered that the iron ions are taken in and fixed in calcium carbonate, and the iron ions remaining on the calcium carbonate surface adsorb and fix heavy metals. When the content ratio of calcium ions and iron ions is in the above range, the amount of heavy metal immobilized during precipitation of calcium carbonate is compared with the amount of heavy metal immobilized during precipitation of calcium carbonate by calcium ions alone. , Increase more. Further, even when the amount of heavy metal immobilized when iron hydroxide is formed by iron ion alone is taken into consideration, more efficient heavy metal immobilization is performed by using calcium ion and iron ion together. For this reason, even if compared with the composition for soil improvement which contains calcium ion and iron ion each independently, it is thought that the immobilization efficiency of heavy metal increased more.
However, the present invention is not limited to the above estimation mechanism.
本発明の不溶化処理組成物は、２５℃における粘度が１×１０−３Ｐａ・ｓ〜１．５×１０−３Ｐａ・ｓであることが、土壌への浸透性が良好となるという観点から好ましく、１×１０−３Ｐａ・ｓ〜１．２×１０−３Ｐａ・ｓであることがより好ましい。
不溶化処理組成物の粘度が上記範囲であることで、不溶化処理組成物を土壌へ注入する際に、掘削などを行なうことなく、直接土壌へ適用して浸透させることができる。このため、２５℃における粘度を上記範囲とすることで、例えば、不溶化処理組成物を注入井戸により土壌へ注入することができる。また、土壌中での拡散性もより良好となることから、粘度を上記範囲に調整することが好ましい。
不溶化処理組成物の粘度は、ファンギラブ社製 ラボ用デジタル式回転粘度計 単一円筒型回転粘度計（スピンドルタイプ）を用いて、ＪＩＳ Ｋ７１１７−１（１９９１年）に記載の方法に準拠して測定した。
From the viewpoint that the insolubilization treatment composition of the present invention has a viscosity of 1 × 10 −3 Pa · s to 1.5 × 10 −3 Pa · s at 25 ° C., the soil permeability becomes good. Preferably, it is 1 × 10 −3 Pa · s to 1.2 × 10 −3 Pa · s.
When the viscosity of the insolubilized composition is within the above range, when the insolubilized composition is injected into the soil, it can be directly applied to the soil and infiltrated without excavation. For this reason, by making the viscosity in 25 degreeC into the said range, an insolubilization processing composition can be inject | poured into soil by an injection well, for example. Moreover, since the diffusibility in soil also becomes more favorable, it is preferable to adjust a viscosity to the said range.
Viscosity of the insolubilized composition is measured in accordance with the method described in JIS K7117-1 (1991) using a laboratory-use digital rotary viscometer (spindle type) manufactured by Fungilab. did.
不溶化処理組成物は、常法によりオーガーなどを用いて土壌に注入し、混合することもできる。機械的な掘削装置、混合装置を用いて不溶化処理組成物を土壌に適用する場合には、不溶化処理組成物の粘度が上記範囲を超える範囲であっても問題はない。しかし、土壌中での浸透性を考慮すれば、粘度が低い不溶化処理組成物を用いることが、１回の注入により、より広範な範囲の土壌の修復を行なうことができるため好ましい。 The insolubilized composition can be poured into the soil using an auger or the like by a conventional method and mixed. In the case where the insolubilized composition is applied to soil using a mechanical drilling device or a mixing device, there is no problem even if the viscosity of the insolubilized composition is in the range exceeding the above range. However, in consideration of permeability in soil, it is preferable to use an insolubilized composition having a low viscosity because a wider range of soil can be repaired by a single injection.
(その他の成分）
本発明の不溶化処理組成物には、ウレアーゼ生成微生物、尿素、カルシウムイオン、及び鉄イオンに加え、本発明の効果を損なわない範囲において他の成分を含有することができる。
不溶化処理組成物には、ウレアーゼ生成微生物の活性をより高める目的で、尿素に加え、ウレアーゼ生成微生物が資化可能な栄養剤を含有することができる。
予め、尿素、栄養剤、カルシウム源である塩化カルシウムなどを含有する固化溶液を調製し、得られた固化溶液とウレアーゼ生成微生物を含む菌体培養液とを用いて不溶化処理組成物を得ることができる。鉄イオンは固化溶液に添加してもよく、別途、不溶化処理組成物に加えてもよい。
(Other ingredients)
The insolubilizing treatment composition of the present invention can contain other components in addition to urease-producing microorganisms, urea, calcium ions, and iron ions as long as the effects of the present invention are not impaired.
In addition to urea, the insolubilizing composition may contain a nutrient capable of assimilating the urease-producing microorganism in order to further increase the activity of the urease-producing microorganism.
A solidified solution containing urea, nutrients, calcium chloride as a calcium source, etc. is prepared in advance, and an insolubilized composition is obtained using the obtained solidified solution and a cell culture solution containing urease-producing microorganisms. it can. Iron ions may be added to the solidified solution or separately to the insolubilized composition.
固化溶液に用いうる栄養剤には特に制限はなく、微生物の培養に使用される有機物、無機塩等から選ばれる公知の栄養剤を使用することができる。
有機物は、具体的には、酵母エキス、肉エキス、麦芽エキス、魚エキス、ペプトン、スクロース、トリプトン、グルコース、ジャガイモ抽出液、廃糖蜜、コンポスト廃液のしぼり汁等が挙げられる。
無機塩は、具体的には、ＫＨ２ＰＯ４、Ｎａ２ＨＰＯ４等のリン酸塩、ＮＨ４Ｃｌ等のアンモニア塩、ＫＮＯ３、ＮＨ４ＮＯ３等の硝酸塩、微量金属元素溶液等が挙げられる。無機塩のうち、塩化アンモニウム（ＮＨ４Ｃｌ）、硝酸カリウム（ＫＮＯ３）、硝酸アンモニウム（ＮＨ４ＮＯ３）等は微生物が増殖する際の窒素源として有用である。
固化溶液には、栄養剤を１種単独で用いてもよく、２種以上を併用してもよい。
There is no restriction | limiting in particular in the nutrient which can be used for a solidification solution, The well-known nutrient selected from the organic substance, inorganic salt, etc. which are used for culture | cultivation of microorganisms can be used.
Specific examples of the organic substance include yeast extract, meat extract, malt extract, fish extract, peptone, sucrose, tryptone, glucose, potato extract, molasses, and squeezed juice of compost waste.
Specific examples of the inorganic salt include phosphates such as KH 2 PO 4 and Na 2 HPO 4 , ammonia salts such as NH 4 Cl, nitrates such as KNO 3 and NH 4 NO 3 , trace metal element solutions, and the like. It is done. Among inorganic salts, ammonium chloride (NH 4 Cl), potassium nitrate (KNO 3 ), ammonium nitrate (NH 4 NO 3 ) and the like are useful as a nitrogen source when microorganisms grow.
In the solidified solution, one type of nutrient may be used alone, or two or more types may be used in combination.
固化溶液には、栄養剤の他、ｐＨ調整剤、緩衝剤などの公知の成分を含むことができる。固化溶液が、ｐＨ調整剤、緩衝剤等を適切な量で含むことで、不溶化処理組成物のｐＨを、微生物に良好な領域に維持することができる。
ｐＨ調整剤としては、炭酸水素ナトリウムなどが挙げられる。緩衝剤としては、トリスヒドロキシメチルアミノメタン等が挙げられる。
The solidified solution can contain known components such as a pH adjuster and a buffer in addition to the nutrient. When the solidification solution contains a pH adjusting agent, a buffering agent, and the like in appropriate amounts, the pH of the insolubilized composition can be maintained in a region favorable for microorganisms.
Examples of the pH adjuster include sodium bicarbonate. Examples of the buffer include trishydroxymethylaminomethane.
本発明の不溶化処理組成物は、流動性に優れ、土壌への浸透性と、重金属の不溶化処理効率を両立させ得るため、既述の成分を含む１液構成の組成物とすることができる。
また、流動性をより向上させる観点からは、尿素とカルシウムイオンと鉄イオンとを含む第１液と、菌体培養液を含む第２液とからなる２液構成、或いは、菌体培養液と尿素とを含む第１液と、カルシウムイオンと鉄イオンと含む第２液とからなる２液構成の組成物とすることができる。
The insolubilization treatment composition of the present invention is excellent in fluidity and can achieve both soil permeability and heavy metal insolubilization treatment efficiency, and therefore can be made into a one-component composition containing the aforementioned components.
In addition, from the viewpoint of further improving the fluidity, a two-liquid configuration comprising a first liquid containing urea, calcium ions, and iron ions and a second liquid containing a bacterial cell culture solution, or a bacterial cell culture solution, It can be set as the composition of 2 liquid composition which consists of the 1st liquid containing urea and the 2nd liquid containing a calcium ion and an iron ion.
＜重金属汚染土壌の修復方法＞
本発明の重金属汚染土壌の修復方法は、ウレアーゼ生成微生物と、尿素と、カルシウムイオンと、鉄イオンと、を含み、前記カルシウムイオンの含有量をＡ（ｍｇ／Ｌ）とし、前記鉄イオンの含有量をＢ（ｍｇ／Ｌ）としたとき、ＡとＢとの関係が、下記式（１）、下記式（２）及び下記式（３）の条件を満たす重金属不溶化処理組成物を、処理対象土壌に注入することを含む、重金属汚染土壌の修復方法である。
式（１）：２／１≦Ａ／Ｂ≦２０／１（質量基準）
式（２）：５４ｍｇ／Ｌ≦Ａ≦３０００ｍｇ／Ｌ
式（３）：１５ｍｇ／Ｌ≦Ｂ≦３００ｍｇ／Ｌ
<Repairing heavy metal contaminated soil>
The method for repairing heavy metal-contaminated soil according to the present invention includes urease-producing microorganisms, urea, calcium ions, and iron ions, wherein the content of calcium ions is A (mg / L), and the iron ions are contained. When the amount is B (mg / L), a heavy metal insolubilized composition in which the relationship between A and B satisfies the conditions of the following formula (1), the following formula (2), and the following formula (3) is treated. A method for repairing heavy metal contaminated soil, including pouring into soil.
Formula (1): 2/1 ≦ A / B ≦ 20/1 (mass basis)
Formula (2): 54 mg / L ≦ A ≦ 3000 mg / L
Formula (3): 15 mg / L ≦ B ≦ 300 mg / L
不溶化処理組成物の注入方法には特に制限はなく、公知の地盤改良方法、土壌改良方法に適用される方法はいずれも本発明の修復方法に適用することができる。
注入方法としては、対象となる重金属汚染土壌表面に不溶化処理組成物を散布する方法、注入井戸を用いて注入する方法、既述のＤＣＭ工法を適用する方法等が挙げられる。
There is no restriction | limiting in particular in the injection | pouring method of an insolubilization process composition, All the methods applied to the well-known ground improvement method and the soil improvement method can be applied to the restoration | repair method of this invention.
Examples of the injection method include a method of spraying the insolubilized composition on the surface of the heavy metal contaminated soil, a method of injecting using an injection well, and a method of applying the DCM method described above.
本発明の修復方法に用いられる不溶化処理組成物は流動性が良好であるため、注水井戸を用いて土壌に注入することができる。
図１は、本発明の重金属汚染土壌の修復方法に適用することができる不溶化処理組成物供給用の注入井戸１０を示すモデル図である。注入井戸１０は飽和帯水層に至る筒状の形状を有し、筒状の部材の先端部近傍、図１によれば、飽和帯水層に達する部分に、不溶化処理組成物を土壌へ注入するための図示されない開孔部を筒状の部材の側壁に有する。注入井戸１０の地上部から供給された不溶化処理組成物は、注入井戸の先端部近傍に設けられた開孔部から土壌に注入され、周囲の土壌に拡散し、土壌中の重金属の不溶化が進行して土壌が修復される。
予め定められた領域の土壌を修復する場合には、不溶化処理組成物を土壌へ注入する注入井戸１０と所定の間隔を置いて図２に示す吸入井戸１２を設置し、土壌の修復に用いられた不溶化処理組成物を回収することができる。図２に示すように注入井戸１０と吸入井戸１２を用いる場合、注入井戸１０と吸入井戸１２との間に、処理対象土壌が位置するように注入井戸１０と吸入井戸１２とを配置することにより、不溶化処理組成の土壌中での流動方向が制御され、土壌の修復がより効率よく行なわれる。さらに、吸入井戸１２により土壌中の重金属を固定化した固形分を含む使用後の不溶化処理組成物、或いは、反応に関与しなかった不溶化処理を回収することで、不溶化処理組成物の周囲への拡散を抑制することができる。
Since the insolubilization treatment composition used for the restoration method of the present invention has good fluidity, it can be injected into the soil using a water injection well.
FIG. 1 is a model diagram showing an injection well 10 for supplying an insolubilized composition that can be applied to the method for repairing heavy metal contaminated soil of the present invention. The injection well 10 has a cylindrical shape that reaches the saturated aquifer. According to FIG. 1, the insolubilized composition is injected into the soil near the tip of the cylindrical member, according to FIG. An opening (not shown) is provided on the side wall of the cylindrical member. The insolubilizing composition supplied from the above-ground part of the injection well 10 is injected into the soil from the opening provided in the vicinity of the tip of the injection well, diffuses into the surrounding soil, and insolubilization of heavy metals in the soil proceeds. The soil is restored.
When the soil in a predetermined region is to be repaired, the suction well 12 shown in FIG. 2 is installed at a predetermined interval from the injection well 10 for injecting the insolubilized composition into the soil, and used for soil repair. The insolubilized composition can be recovered. When the injection well 10 and the suction well 12 are used as shown in FIG. 2, the injection well 10 and the suction well 12 are arranged so that the soil to be treated is located between the injection well 10 and the suction well 12. In addition, the direction of flow of the insolubilized composition in the soil is controlled, and the soil is repaired more efficiently. Furthermore, by recovering the insolubilization treatment composition after use containing the solid content in which heavy metals in the soil are fixed by the suction well 12, or the insolubilization treatment not involved in the reaction, Diffusion can be suppressed.
図１及び図２に示すように、不溶化処理組成物は、土壌に注入され、土壌中の飽和帯水層に至り、周辺土壌へ拡散する。飽和帯水層では、既述のように、土壌粒子間の有効間隙が水で満たされており、この水を間隙水と称する。注入された不溶化処理組成物は土壌粒子間に存在する間隙水により希釈されることになる。
地盤における有効間隙は、土壌１ｍ３当たり、一般には０．２ｍ３程度であることが知られており、飽和帯水層中において希釈された不溶化処理組成物における各成分が。重金属の不溶化に有効な濃度となるように、本発明の土壌の修復方法では、不溶化処理組成物の濃度および注入量を適宜、決定することが好ましい。
As shown in FIGS. 1 and 2, the insolubilized composition is injected into the soil, reaches a saturated aquifer in the soil, and diffuses into the surrounding soil. In the saturated aquifer, as described above, the effective gap between the soil particles is filled with water, and this water is referred to as pore water. The injected insolubilized composition will be diluted with pore water present between the soil particles.
Effective gap in soil is soil 1 m 3 per popularly known to be about 0.2 m 3, the respective components in the insolubilizing treatment composition diluted in saturated aquifer in is. In the soil repair method of the present invention, it is preferable to appropriately determine the concentration and the amount of the insolubilized composition so that the concentration is effective for insolubilizing heavy metals.
既述のように、不溶化処理組成物を土壌に注入した後、不溶化処理組成物は土壌粒子の間隙に存在する間隙水により希釈される。効果の観点からは、不溶化処理組成物が土壌中に到達して土壌の修復が行なわれる際の実質的な濃度としては、カルシウムイオンの含有量は、１８ｍｇ／Ｌ〜１０００ｍｇ／Ｌの範囲が好ましく、６０ｍｇ／Ｌ〜６００ｍｇ／Ｌの範囲がより好ましく、１８０ｍｇ／Ｌ〜６００ｍｇ／Ｌの範囲がさらに好ましい。同様に、鉄イオンの含有量は、間隙水により希釈された後は、５ｍｇ／Ｌ〜１００ｍｇ／Ｌの範囲であることが好ましく、１０ｍｇ／Ｌ〜５０ｍｇ／Ｌの範囲がより好ましい。不溶化処理組成物が土壌中で希釈された後のカルシウムイオン及び鉄イオンの含有量が上記範囲となることで、土壌中の重金属を効果的に不溶化するための炭酸カルシウムの析出、水酸化鉄の析出及び炭酸カルシウム表面における鉄イオンによる重金属の吸着が効率よく行なわれる。
したがって、本発明の修復方法では、間隙水による希釈後の濃度を勘案して、土壌中で機能する際の不溶化処理組成物に含まれるカルシウムイオン及び鉄イオン濃度を既述の範囲に調整することが好ましい。即ち、土壌中で機能する実質的な有効成分の濃度を考慮して、不溶化処理組成物の土壌への注入量、土壌へ注入する前の不溶化処理組成物の濃縮或いは希釈条件等を必要に応じて制御することが好ましい。
As described above, after the insolubilized composition is injected into the soil, the insolubilized composition is diluted with pore water present in the gaps between the soil particles. From the viewpoint of the effect, as a substantial concentration when the insolubilized composition reaches the soil and the soil is repaired, the calcium ion content is preferably in the range of 18 mg / L to 1000 mg / L. The range of 60 mg / L to 600 mg / L is more preferable, and the range of 180 mg / L to 600 mg / L is more preferable. Similarly, the iron ion content after dilution with pore water is preferably in the range of 5 mg / L to 100 mg / L, and more preferably in the range of 10 mg / L to 50 mg / L. When the content of calcium ions and iron ions after the insolubilized composition is diluted in the soil is in the above range, precipitation of calcium carbonate for effectively insolubilizing heavy metals in the soil, Precipitation and adsorption of heavy metals by iron ions on the surface of calcium carbonate are performed efficiently.
Therefore, in the restoration method of the present invention, the calcium ion and iron ion concentrations contained in the insolubilized composition when functioning in the soil are adjusted to the above-mentioned ranges in consideration of the concentration after dilution with pore water. Is preferred. That is, considering the concentration of the effective active ingredient that functions in the soil, the amount of the insolubilized composition to be injected into the soil, the concentration or dilution conditions of the insolubilized composition before being injected into the soil, as necessary It is preferable to control.
例えば、修復処理対象土壌１００ｍ３の場合、処理対象土壌粒に存在する間隙水の水量は、１００ｍ３×０．２＝２０ｍ３と見積もることができる。不溶化処理組成物の間隙水水量に対する注入量を注入率と称し、注入率は実質的に、１０％〜７０％程度で実施されることが一般的であり、好ましくは、２０％〜５０％程度である。
例えば、注入率を２０％とし、土壌中で間隙水により希釈された場合の有効な鉄イオン濃度の目標を好適な２０ｍｇ／Ｌとした場合、希釈前の不溶化処理組成物における鉄イオンの濃度は、２０ｍｇ／Ｌ÷０．２（２０％）＝１００ｍｇ／Ｌと見積もることができ、希釈前の不溶化処理組成物における鉄イオンの含有量は１００ｍｇ／Ｌとすればよい。
なお、本発明の修復方法における効果に影響を与えるのは、最終的に注入後の間隙水により希釈された不溶化処理組成物の有効成分の含有量である。ここでは、鉄イオン濃度を例に検討したが、カルシウムイオン、菌体濃縮液等の使用時における各種有効成分の含有量も、同様である。いずれの有効成分についても、注入後の間隙水により希釈された濃度における有効量と、実際の処理対象土壌における間隙水の含有量とを考慮して、不溶化処理組成物の処方及び注入率を、効果を勘案して決定すればよい。
For example, in the case of 100 m 3 of the restoration target soil, the amount of pore water present in the treatment target grain can be estimated as 100 m 3 × 0.2 = 20 m 3 . The injection amount of the insolubilized composition with respect to the amount of pore water is referred to as an injection rate, and the injection rate is generally substantially 10% to 70%, preferably about 20% to 50%. It is.
For example, when the injection rate is 20% and the target of effective iron ion concentration when diluted with pore water in soil is 20 mg / L, the concentration of iron ions in the insolubilized composition before dilution is 20 mg / L / 0.2 (20%) = 100 mg / L, and the content of iron ions in the insolubilized composition before dilution may be 100 mg / L.
In addition, it is content of the active ingredient of the insolubilization processing composition finally diluted with the pore water after injection | pouring that affects the effect in the restoration | repair method of this invention. Here, the iron ion concentration was examined as an example, but the contents of various active ingredients when using calcium ions, bacterial cell concentrates, and the like are also the same. For any active ingredient, in consideration of the effective amount at a concentration diluted with pore water after injection and the content of pore water in the actual treatment target soil, the formulation of the insolubilized treatment composition and the injection rate, It may be determined in consideration of the effect.
本発明の土壌修復方法において土壌への注入に用いる不溶化処理組成物は、ウレアーゼ生成微生物、尿素、カルシウムイオン、及び鉄イオンを含有する１液構成であってもよく、ウレアーゼ生成微生物の菌体培養液と尿素とを含む第１液と、カルシウムイオンと鉄イオンとを特定の比率、特定の含有量で含む第２液との２液構成でもよく、ウレアーゼ生成微生物の菌体培養液を含む第１液と、尿素と、カルシウムイオンと、鉄イオンとを含む第２液との２液構成としてもよい。
既述の本発明の不溶化処理組成物は、以下に述べるように水と殆ど変わらない流動性を有することから、１液構成の組成物であっても土壌にそのまま注入することで十分な効果を奏する。
また、浸透性をより向上させる観点からは、土壌への注入から深部へ到達するまでの流動性により優れ、土壌中に拡散した後に炭酸カルシウムの析出が開始される２液構成の不溶化処理組成物としてもよい。
The insolubilizing composition used for the injection into the soil in the soil repair method of the present invention may be a one-component composition containing urease-producing microorganisms, urea, calcium ions, and iron ions, and the cell culture of urease-producing microorganisms A two-component configuration of a first solution containing a solution and urea and a second solution containing calcium ions and iron ions in a specific ratio and a specific content may be used, and a cell culture solution containing urease-producing microorganisms may be used. It is good also as 2 liquid composition of 1 liquid, urea, calcium ion, and 2nd liquid containing iron ion.
Since the insolubilization treatment composition of the present invention described above has fluidity that is almost the same as water as described below, even if it is a one-component composition, a sufficient effect can be obtained by injecting it as it is into the soil. Play.
Moreover, from the viewpoint of further improving the permeability, the two-component insolubilized composition is excellent in fluidity from injection into the soil until reaching the deep part, and starts to precipitate calcium carbonate after diffusing into the soil. It is good.
本発明の不溶化処理組成物は浸透性に優れるため、そのまま注入してもよいが、土壌と効率よく接触させるため、不溶化処理組成物を土壌へ注入した後、土壌の機械的な撹拌を行なってもよい。
本発明の修復方法によれば、不溶化処理組成物が高い浸透性を実現し、土壌注入後に炭酸カルシウム等が析出し、カルシウムイオン及び鉄イオンとの共存により、カルシウム塩内に効率よく重金属を封じ込め、かつ、カルシウム塩の表面において鉄イオンが更に重金属を吸着し、固定化することで、重金属汚染土壌を効果的に修復することができる。
Since the insolubilized composition of the present invention is excellent in permeability, it may be injected as it is, but in order to efficiently contact with the soil, the insolubilized composition is injected into the soil and then mechanically stirred in the soil. Also good.
According to the repair method of the present invention, the insolubilized composition achieves high permeability, calcium carbonate and the like are precipitated after soil injection, and the heavy metal is efficiently contained in the calcium salt by coexistence with calcium ions and iron ions. In addition, iron ions further adsorb and immobilize heavy metals on the surface of the calcium salt, so that heavy metal-contaminated soil can be effectively repaired.
（土壌中の不溶化処理組成物の移動特性について）
土壌中の液体の動きについて考察する。
間隙を水で飽和された土壌粒子間を移動する水の動きは、一般的にダルシーの法則（Ｄａｒｃｙ’ｓ Ｒａｗ）に従う。
Ｑ＝ｋ・Ａ・ｉ
上記式中、Ｑ［ｍ３／ｓ］は、透過液流量を表し、ｋ［ｍ・ｓ−１］は透水係数であり、Ａ［ｍ２］は透過面積であり、ｉ［ｍ・ｍ−１］は動水勾配を表す。
(Movement characteristics of insolubilized composition in soil)
Consider the movement of liquid in the soil.
The movement of water moving between soil particles saturated with water in the gap generally follows Darcy's Law.
Q = k ・ A ・ i
In the above formula, Q [m 3 / s] represents a permeate flow rate, k [m · s −1 ] is a water permeability coefficient, A [m 2 ] is a permeation area, and i [m · m − 1 ] represents a hydraulic gradient.
（固有透過度と透水係数の関係）
透水係数ｋは、さらに流体の密度ρ［ｋｇ・ｍ−３］、重力加速度ｇ［ｍ・ｓ−２］、粘度μ［Ｐａ・ｓ］、固有透過度Ｋ［ｍ２］を用いて、以下の関係式が成立する。
ｋ＝Ｋ・ρｇ／μ
固有透過度Ｋとは、土壌などの多孔質体自身の構造特性に由来する透過抵抗であり、粒径分布・粒子の形状・屈曲度・空隙率などから決定される。
一般的に用いられる透水係数は、密度１［ｇ／ｃｍ３］、粘度１［ｍＰａ・ｓ］（１×１０−３Ｐａ・ｓ：温度２０℃）の水が、土壌中などを移動する前提条件で決定されており、密度、粘度が異なる流体の地盤中の移動速度を計算する際には、流体の密度・粘度で補正する必要がある。
(Relationship between intrinsic permeability and hydraulic conductivity)
The water permeability coefficient k is further expressed as follows using the fluid density ρ [kg · m −3 ], gravity acceleration g [m · s −2 ], viscosity μ [Pa · s], and intrinsic permeability K [m 2 ]. The following relational expression holds.
k = K · ρg / μ
The intrinsic permeability K is a permeation resistance derived from the structural characteristics of the porous body itself such as soil, and is determined from the particle size distribution, the shape of the particles, the degree of bending, the porosity, and the like.
The water permeability coefficient generally used is based on the assumption that water having a density of 1 [g / cm 3 ] and a viscosity of 1 [mPa · s] (1 × 10 −3 Pa · s: temperature 20 ° C.) moves through the soil and the like. It is determined by the conditions, and when calculating the moving speed of fluids with different densities and viscosities in the ground, it is necessary to correct with the density and viscosity of the fluid.
（不溶化処理組成物の地盤への注入）
図１のモデル図に示すように、注入井戸を用いて、不溶化処理組成物を土壌中に注入した際には、注入井戸の先端近傍から、周囲の土壌に不溶化処理組成物が拡散する。
重金属汚染土壌及び重金属を含有する地下水汚染の修復方法として注入工法を用いる場合には、コストの観点から、できるだけ少ない井戸本数とすることが好ましい。
不溶化処理組成物を土壌中に効率よく拡散させるためには、地盤の透水性（固有透過度）が大きいこと、組成物の注入圧力（動水勾配）が大きいこと、組成物の粘度が小さいこと、組成物の密度が大きいことが好ましい。
ここで、同じ土壌に不溶化処理組成物を注入する場合、制御可能なパラメーターとしては「粘度μ」と「注入圧力」が挙げられる。
常温（２０℃）での水の粘度は、約１［ｍＰａ・ｓ］、即ち、約１×１０−３Ｐａ・ｓであることが知られている。これに対し、以下の実施例にて詳述するが、本発明の不溶化処理組成物の粘度は、１．０２×１０−３Ｐａ・ｓであり、水とほとんど変わらない。
このことからも、本発明の重金属不溶化処理組成物の土壌への浸透性が良好であることが裏付けられるといえる。
(Infusion of insolubilized composition into the ground)
As shown in the model diagram of FIG. 1, when an insolubilization treatment composition is injected into soil using an injection well, the insolubilization treatment composition diffuses into the surrounding soil from the vicinity of the tip of the injection well.
When the injection method is used as a method for repairing heavy metal-contaminated soil and groundwater contamination containing heavy metals, the number of wells is preferably as small as possible from the viewpoint of cost.
In order to efficiently disperse the insolubilized composition into the soil, the water permeability (inherent permeability) of the ground is large, the injection pressure (dynamic gradient) of the composition is large, and the viscosity of the composition is small. It is preferable that the density of the composition is large.
Here, when insolubilizing composition is injected into the same soil, “viscosity μ” and “injection pressure” can be mentioned as controllable parameters.
It is known that the viscosity of water at room temperature (20 ° C.) is about 1 [mPa · s], that is, about 1 × 10 −3 Pa · s. In contrast, as described in detail in the following examples, the viscosity of the insolubilized composition of the present invention is 1.02 × 10 −3 Pa · s, which is almost the same as water.
This also confirms that the heavy metal insolubilization treatment composition of the present invention has good soil permeability.
また、他方の制御可能なパラメーターである注入圧力については、本発明の不溶化処理組成物が流動性に優れることから、一般的な土壌に供給する場合には、特に制御する必要はない。
しかし、処理対象土壌の物性、処理対象土壌の量、土壌が存在する環境などを考慮して、必要に応じて不溶化処理組成物の供給に加圧手段を用いてもよい。
例えば、不溶化処理組成物をポンプで圧送すること、オーガーなどを用いて掘削と機械的撹拌手段を併用して不溶化処理組成物を供給すること等の手段をとることができる。
Further, the injection pressure, which is the other controllable parameter, does not need to be particularly controlled when supplied to general soil because the insolubilized composition of the present invention is excellent in fluidity.
However, in consideration of the physical properties of the soil to be treated, the amount of the soil to be treated, the environment in which the soil exists, a pressurizing means may be used to supply the insolubilized treatment composition as necessary.
For example, it is possible to take measures such as pumping the insolubilizing composition with a pump, or supplying the insolubilizing composition using an auger or the like in combination with excavation and mechanical stirring means.
本発明の重金属汚染土壌の修復方法によれば、重金属に汚染された土壌を、掘削、搬出することなく原位置で簡易に修復することができる。本発明の修復方法に用いられる不溶化処理組成物は、流動性が高く、土壌への浸透性が良好であり、重金属の不溶化効果に優れるため、原位置土壌に直接不溶化処理組成物を供給してもよく、また、公知の地盤改良方法、土壌修復方法に用いられる手段を併用して土壌へ不溶化処理組成物を供給してもよい。
このため、本発明の重金属汚染土壌の修復方法は、重金属汚染土壌における重金属の不溶化効果に優れ、重金属汚染土壌を原位置で簡易に処理することができるため、その応用範囲は広い。
また、本発明の方法に用いる不溶化処理組成物は、尿素、カルシウムイオン及び鉄イオンを含有し、周囲の環境に影響を与える懸念がない。さらに、本発明の好ましい態様では、ウレアーゼ生成微生物として、処理対象の原位置土壌から採取した微生物を培養して用いることで、原位置土壌における生態系等の環境に対する影響をより低減することができる。
According to the method for repairing heavy metal contaminated soil of the present invention, soil contaminated with heavy metal can be easily repaired in situ without being excavated and carried out. The insolubilization treatment composition used in the restoration method of the present invention has high fluidity, good permeability to soil, and excellent insolubilization effect of heavy metals. Alternatively, the insolubilized composition may be supplied to the soil using a combination of means used in known ground improvement methods and soil remediation methods.
For this reason, the method for repairing heavy metal-contaminated soil of the present invention is excellent in the insolubilizing effect of heavy metals in heavy metal-contaminated soil and can easily treat heavy metal-contaminated soil in situ.
Moreover, the insolubilization processing composition used for the method of this invention contains urea, a calcium ion, and an iron ion, and there is no concern which affects the surrounding environment. Furthermore, in a preferred embodiment of the present invention, the microorganisms collected from the in-situ soil to be treated are cultured and used as the urease-producing microorganism, so that the influence on the environment such as the ecosystem in the in-situ soil can be further reduced. .
以下、具体例を挙げて本発明を詳細に説明するが、本発明は以下の実施例に限定されるものではない。 EXAMPLES Hereinafter, although a specific example is given and this invention is demonstrated in detail, this invention is not limited to a following example.
〔実施例１〜実施例５、比較例１〜比較例３〕
１．ウレアーゼ生成微生物の準備
原位置に生息するウレアーゼ生成微生物による重金属不溶化を目的として、高い加水分解反応を持つＢａｃｉｌｌｕｓ ｐａｓｔｅｕｒｉｉ（最適ｐＨ９）を使用した。Ｂａｃｉｌｌｕｓ ｐａｓｔｅｕｒｉｉ の培養にはＮＨ４−ＹＥ培地による液体培地を用いた。ＮＨ４−ＹＥ培地の組成を下記表１に示す。液体培地は、酵母エキスに加え、窒素源としての硫酸アンモニウム、緩衝液としてのトリスヒドロキシメチルアミノメタン(下記、表１には、「０．１３Ｍ Ｔｒｉｓ」と略記する）を含有する。
[Example 1 to Example 5, Comparative Example 1 to Comparative Example 3]
1. Preparation of urease-producing microorganisms Bacillus pasteurii (optimum pH 9) having a high hydrolysis reaction was used for the purpose of insolubilizing heavy metals by urease-producing microorganisms that live in situ. For culture of Bacillus pasteurii, a liquid medium using NH4-YE medium was used. The composition of the NH4-YE medium is shown in Table 1 below. In addition to the yeast extract, the liquid medium contains ammonium sulfate as a nitrogen source and trishydroxymethylaminomethane (hereinafter abbreviated as “0.13M Tris” in Table 1) as a buffer solution.
培養したＢａｃｉｌｌｕｓ ｐａｓｔｅｕｒｉｉの活性は、菌体培養液に尿素溶液を混合させ加水分解により発生するアンモニアと炭酸イオンの量を、電気伝導の変化を測定することで評価を行い、活性が安定して高い培養後７日〜１０日での菌体培養液を用いた。 The activity of cultured Bacillus pasteurii is evaluated by measuring the amount of ammonia and carbonate ions generated by hydrolysis by mixing a urea solution in the cell culture medium, and measuring the change in electrical conductivity. The cell culture broth 7 to 10 days after the culture was used.
２．不溶化処理組成物の調製
２質量％の菌体培養液を用い、尿素（和光純薬(株）：尿素）、カルシウムイオン源としての塩化カルシウム（和光純薬(株）：塩化カルシウム）、鉄イオン源としての鉄イオン溶液（和光純薬(株）、硫酸第一鉄七水和物）を用いて、下記表２に示すカルシウムイオン、及び鉄イオンの含有量となる実施例１〜実施例５、比較例1〜比較例３の重金属不溶化処理組成物を調製した。
尿素は水に溶解させて濃度５質量％の尿素水溶液を調製し、１時間保存した後に不溶化処理組成物の調製に使用した。
不溶化処理組成物の成分を十分に撹拌混合して不溶化処理組成物を得た。
その後、得られた各重金属不溶化処理組成物を、間隙水により希釈されたモデルとするため、水で３倍に希釈した。希釈後のカルシウムイオン、鉄イオン、及び尿素の含有量は、下記表２に示すとおりである。
2. Preparation of insolubilized composition Urea (Wako Pure Chemical Industries, Ltd .: urea), calcium chloride as a calcium ion source (Wako Pure Chemical Industries, Ltd .: calcium chloride), iron ions Examples 1-5 which become the content of the calcium ion and iron ion which are shown in following Table 2 using the iron ion solution (Wako Pure Chemical Industries, Ltd., ferrous sulfate heptahydrate) as a source The heavy metal insolubilization treatment compositions of Comparative Examples 1 to 3 were prepared.
Urea was dissolved in water to prepare an aqueous urea solution having a concentration of 5% by mass, and after storage for 1 hour, it was used to prepare an insolubilized composition.
The components of the insolubilization treatment composition were sufficiently stirred and mixed to obtain an insolubilization treatment composition.
Then, in order to make each obtained heavy metal insolubilization processing composition into the model diluted with pore water, it diluted with water 3 times. The contents of calcium ions, iron ions, and urea after dilution are as shown in Table 2 below.
３．不溶化処理組成物の評価
得られた実施例１の不溶化処理組成物の３倍希釈物を、重金属汚染土壌のモデルとしての標準試薬を用いて調製したヒ素溶液（ヒ素濃度：１ｍｇ／Ｌ)と混合し、混合物におけるヒ素の初期濃度を０．１ｍｇ／Ｌに調整した。得られた混合物を室温で２４時間静置した後、残存するヒ素濃度を測定した。
実際の汚染現場におけるヒ素の汚染濃度は、実測値で０．０２ｍｇ／Ｌ〜０．０５ｍｇ／Ｌであることが一般的であり、本評価におけるヒ素の初期濃度０．１ｍｇ／Ｌは高い値に設定されている。したがって、本評価は汚染対象土壌として厳しい条件におけるヒ素濃度低減効果の確認を目的としている。
なお、土壌修復の目標値は地下水環境基準（ヒ素濃度：０．０１ｍｇ／Ｌ以下）である。既述の汚染現場におけるヒ素濃度を勘案すれば、初期濃度に対して７０％〜８０％以上の低減効果が認められれば、通常の修復対象土壌では、地下水環境基準に到達することが可能であり、修復対象土壌の状態によっては、十分に濃度低減効果があると考えられる。
混合液中に残存するヒ素濃度の測定は、ＪＩＳ Ｋ０１０２ ６１．２（２０１３年）に記載の原子吸光光度法に準拠して行なった。
結果を表２に併記する。
表２に示すように、本発明の不溶化処理組成物を用いた場合、ヒ素は不溶化され、ヒ素濃度はいずれの実施例においても大幅に低減された。なかでも、実施例１、実施例３〜実施例５ではヒ素濃度低減の目標値である「０．０１ｍｇ／Ｌ以下」が達成され、実施例２においても、初期のヒ素濃度に対して８０％の低減が認められた。
他方、カルシウムイオン、鉄イオンのいずれかを含まない比較例１、比較例３、カルシウムイオンと鉄イオンとの比率が本発明の範囲外である比較例２では、不溶化によるヒ素低減効果は殆ど認められなかった。
3. Evaluation of Insolubilization Treatment Composition A three-fold dilution of the obtained insolubilization treatment composition of Example 1 was mixed with an arsenic solution (arsenic concentration: 1 mg / L) prepared using a standard reagent as a model for heavy metal contaminated soil. The initial concentration of arsenic in the mixture was adjusted to 0.1 mg / L. The resulting mixture was allowed to stand at room temperature for 24 hours, and then the remaining arsenic concentration was measured.
The actual contamination concentration of arsenic at the actual contamination site is generally 0.02 mg / L to 0.05 mg / L in actual measurement values, and the initial concentration of arsenic 0.1 mg / L in this evaluation is a high value. Is set. Therefore, this evaluation is aimed at confirming the arsenic concentration reduction effect under severe conditions as contaminated soil.
The target value for soil restoration is the groundwater environmental standard (arsenic concentration: 0.01 mg / L or less). Considering the arsenic concentration in the contaminated site described above, it is possible to reach the groundwater environmental standard in normal restoration target soil if a reduction effect of 70% to 80% or more with respect to the initial concentration is recognized. Depending on the condition of the soil to be repaired, it is considered that there is a sufficient concentration reduction effect.
The concentration of arsenic remaining in the mixture was measured according to the atomic absorption spectrophotometry described in JIS K0102 61.2 (2013).
The results are also shown in Table 2.
As shown in Table 2, when the insolubilized composition of the present invention was used, arsenic was insolubilized and the arsenic concentration was greatly reduced in any of the examples. In particular, in Examples 1 and 3 to 5, the target value for reducing the arsenic concentration was “0.01 mg / L or less”, and in Example 2 as well, 80% of the initial arsenic concentration was achieved. Reduction was observed.
On the other hand, in Comparative Example 1 and Comparative Example 3 that do not contain either calcium ions or iron ions, and in Comparative Example 2 in which the ratio of calcium ions to iron ions is outside the scope of the present invention, the effect of reducing arsenic due to insolubilization is almost recognized. I couldn't.
〔実施例６、実施例７〕
１．ウレアーゼ生成微生物の準備
処理対象土壌中からウレアーゼ産出能を有する微生物を抽出し、集積培養により活性を高めた微生物を用いて実際のヒ素汚染土壌の溶出液に対して不溶化効果の確認を実施した。
ウレアーゼ生成微生物（集積菌）は、土壌サンプルより採取したウレアーゼ生成微生物群に対して、栄養塩類及び尿素を添加し培養を行った。
集積培養法では、菌体培養液を遠心分離によりろ液と菌体に分離し、新たな培養液を添加することで集積効率の向上および必要培養期間が短縮できる。
集積された菌体を、所定濃度の尿素および栄養塩類を加えた培養液に添加し、約３０℃で静置培養することで、７日〜１４日間で本発明の修復方法の実施に使用可能な濃度および液量の菌体培養液を得る。
[Example 6, Example 7]
1. Preparation of urease-producing microorganisms Microorganisms capable of producing urease were extracted from the soil to be treated, and the insolubilization effect was confirmed on the effluent of the actual arsenic-contaminated soil using microorganisms whose activity was enhanced by enrichment culture.
The urease-producing microorganism (accumulated bacteria) was cultured by adding nutrient salts and urea to the urease-producing microorganism group collected from the soil sample.
In the accumulation culture method, the bacterial cell culture medium is separated into filtrate and bacterial cells by centrifugation, and a new culture liquid is added to improve the accumulation efficiency and shorten the required culture period.
The accumulated bacterial cells are added to a culture solution containing a predetermined concentration of urea and nutrient salts, and statically cultured at about 30 ° C., so that the cells can be used for the repair method of the present invention in 7 to 14 days. A cell culture solution of a suitable concentration and volume is obtained.
２．不溶化処理組成物に用いる固化溶液
菌体培養液に対して、微生物の生育に必要な栄養塩及び塩化アンモニウムと、加水分解反応のための尿素と、カルシウム源として塩化カルシウムと、ｐＨ調整剤である炭酸水素ナトリウムとが含まれている固化溶液を使用した。
鉄イオン源としては、鉄イオン溶液（和光純薬（株）硫酸第一鉄七水和物）を使用した。
固化溶液（０．１５ｍｏｌ／Ｌ）の組成を下記表３に示す。
2. Solidification solution used for insolubilization treatment composition Nutrient salt and ammonium chloride necessary for the growth of microorganisms for cell culture solution, urea for hydrolysis reaction, calcium chloride as calcium source, and pH adjuster A solidified solution containing sodium bicarbonate was used.
As the iron ion source, an iron ion solution (Wako Pure Chemical Industries, Ltd., ferrous sulfate heptahydrate) was used.
The composition of the solidified solution (0.15 mol / L) is shown in Table 3 below.
実施例６、７ともに、混合後の濃度として、カルシウムイオン６００ｍｇ／Ｌ、鉄イオン５０ｍｇ／Ｌの条件で不溶化処理組成物を調製し、実施例６では菌体培養液の濃度を０．２％とし、実施例７では菌体培養液の濃度を２．０％とした。 In both Examples 6 and 7, an insolubilized composition was prepared under the conditions of calcium ion 600 mg / L and iron ion 50 mg / L as the concentration after mixing. In Example 6, the concentration of the cell culture broth was 0.2%. In Example 7, the concentration of the bacterial cell culture solution was 2.0%.
３．不溶化処理組成物の評価
実施例６及び実施例７では、ヒ素濃度の初期値として、かなり高濃度のヒ素溶液を使用し、高濃度ヒ素溶液に対する本発明の不溶化処理組成物を用いた際のヒ素濃度低減効果を確認する目的で評価を実施した。
得られた実施例６、実施例７の不溶化処理組成物を、ヒ素汚染土壌の抽出液に注入し、室温で２４時間放置した後、残存するヒ素濃度を測定した。
ヒ素汚染土壌の抽出液の初期ヒ素濃度は、１．５ｍｇ／Ｌである。
その結果、実施例６では、残存するヒ素濃度が０．０３１ｍｇ／Ｌ、実施例７では、残存するヒ素濃度が０．０９０ｍｇ／Ｌであり、初期のヒ素濃度に対して、実施例６では９８％の低減が、実施例７では９４％の低減が認められ、実施例６、実施例７の評価結果より、初期濃度１．５ｍｇ／Ｌの高濃度のヒ素溶液に対しても本発明の不溶化処理組成物を用いることで、ヒ素濃度を著しく低減させる効果が確認できた。
3. Evaluation of Insolubilization Treatment Composition In Examples 6 and 7, a arsenic solution having a considerably high concentration was used as an initial value of the arsenic concentration, and arsenic was obtained when the insolubilization treatment composition of the present invention for the high concentration arsenic solution was used. Evaluation was performed for the purpose of confirming the concentration reduction effect.
The obtained insolubilized compositions of Examples 6 and 7 were poured into an extract of arsenic-contaminated soil and allowed to stand at room temperature for 24 hours, and then the remaining arsenic concentration was measured.
The initial arsenic concentration of the extract of arsenic-contaminated soil is 1.5 mg / L.
As a result, in Example 6, the remaining arsenic concentration was 0.031 mg / L, and in Example 7, the remaining arsenic concentration was 0.090 mg / L. Compared to the initial arsenic concentration, 98 in Example 6 was 98%. % Was found to be 94% in Example 7, and based on the evaluation results of Examples 6 and 7, the insolubilization of the present invention was achieved even in a highly concentrated arsenic solution having an initial concentration of 1.5 mg / L. The effect of significantly reducing the arsenic concentration was confirmed by using the treatment composition.
〔粘度の測定〕
上記実施例３及び実施例４の不溶化処理組成物の３倍希釈後の２５℃における粘度を、ファンギラブ社製 ラボ用デジタル式回転粘度計 単一円筒型回転粘度計（スピンドルタイプ）を用いて、ＪＩＳ Ｋ７１１７−１（１９９１年）に記載の方法に準拠して測定した。
また、対照例として、特許文献１に記載の処理液組成物（対照例１）及び特許文献２に記載の処理液組成物（対照例２）を調製して、実施例３と同じ条件で粘度を測定した。
粘度測定後、各組成物を室温（２５℃）にて３０分静置して、各組成物における沈殿物の発生を目視にて確認したところ、対照例では目視による観察で明らかな沈殿物の発生が確認された。沈殿物をＪＩＳ Ｋ０１０２ １４．１（２０１３年）に記載の方法に準拠して吸引ろ過により分離し、分離した固形分の含有量を測定した。
各組成物に含まれるカルシウムイオン及び鉄イオンの量及び粘度、固形分の含有量の測定結果を下記表５に示す。
(Measurement of viscosity)
The viscosity at 25 ° C. after three-fold dilution of the insolubilized composition of Example 3 and Example 4 above was measured using a digital rotary viscometer for a laboratory manufactured by Fungilab, Inc., a single cylindrical rotary viscometer (spindle type), It measured based on the method as described in JISK7117-1 (1991).
Moreover, as a control example, the processing liquid composition described in Patent Document 1 (Control Example 1) and the processing liquid composition described in Patent Document 2 (Control Example 2) were prepared, and the viscosity was the same as in Example 3. Was measured.
After measuring the viscosity, each composition was allowed to stand at room temperature (25 ° C.) for 30 minutes, and the occurrence of precipitates in each composition was visually confirmed. Occurrence was confirmed. The precipitate was separated by suction filtration in accordance with the method described in JIS K0102 14.1 (2013), and the content of the separated solid was measured.
Table 5 below shows the measurement results of the amounts and viscosities of calcium ions and iron ions contained in each composition and the solid content.
表５の結果より、本発明の不溶化処理組成物は、粘度が低く、流動性が良好であり、経時による固形分の発生が抑制されており、土壌への注入に適することが確認された。
他方、特許文献１及び特許文献２に記載された対象物の処理液組成物は、粘度が高く、土壌への注入が困難であることが分った。また、静置した後の固形分の発生が著しく、土壌の浄化に適用することが実用上困難であることが確認された。
このように、従来技術の処理組成物ではカルシウムイオンはＣａ２＋として２０ｇ／Ｌ〜４０ｇ／Ｌ程度の量で含有し、鉄イオンとしてＦｅ２＋として１２．８ｇ／Ｌとなる量で含有するが、このような処理組成物を使用する場合、表５に記載されるように、粘度は約１２×１０−３Ｐａ・ｓとなり、本発明の不溶化処理組成物と比較すると浸透速度は１／１０程度と極めて小さくなる。
また、実験で確認したところ、経時により多くの水酸化鉄及び水酸化カルシウムである沈殿が生じ、注入時には析出した固形分が土壌の粒子間の間隙を埋めてしまい、継続的な注入は不可能となるものと考えられ、このことから、対照例１、及び対照例２の処理組成物は、地盤への広域な拡散を行なう使用方法には適さないことが確認された。
From the results shown in Table 5, it was confirmed that the insolubilized composition of the present invention had low viscosity, good fluidity, suppressed generation of solids over time, and was suitable for pouring into soil.
On the other hand, it turned out that the processing liquid composition of the target object described in patent document 1 and patent document 2 has a high viscosity, and the injection | pouring to soil is difficult. Moreover, generation | occurrence | production of solid content after leaving still was remarkable, and it was confirmed that it is practically difficult to apply to soil purification.
Thus, in the treatment composition of the prior art, calcium ions are contained as Ca 2+ in an amount of about 20 g / L to 40 g / L, and iron ions are contained in an amount of 12.8 g / L as Fe 2+ . When such a treatment composition is used, as described in Table 5, the viscosity is about 12 × 10 −3 Pa · s, and the penetration rate is about 1/10 compared to the insolubilized treatment composition of the present invention. And extremely small.
In addition, as a result of experiments, it was found that more iron hydroxide and calcium hydroxide precipitates with time, and the solids deposited during filling fill the gaps between the soil particles, making continuous injection impossible. From this, it was confirmed that the treatment compositions of Control Example 1 and Control Example 2 were not suitable for the method of use for performing wide-area diffusion to the ground.
１０ 注入井戸（不溶化処理組成物注入井戸）
１２ 吸入井戸
10 Injection well (Insolubilized composition injection well)
12 Suction well
Claims (4)
前記カルシウムイオンの含有量をＡ（ｍｇ／Ｌ）とし、前記鉄イオンの含有量をＢ（ｍｇ／Ｌ）としたとき、ＡとＢとの関係が、下記式（１）、下記式（２）及び下記式（３）の条件を満たす、重金属不溶化処理組成物。
式（１）：２／１≦Ａ／Ｂ≦２０／１（質量基準）
式（２）：５４ｍｇ／Ｌ≦Ａ≦３０００ｍｇ／Ｌ
式（３）：１５ｍｇ／Ｌ≦Ｂ≦３００ｍｇ／Ｌ
Including urease-producing microorganisms, urea, calcium ions, and iron ions,
When the content of the calcium ions is A (mg / L) and the content of the iron ions is B (mg / L), the relationship between A and B is expressed by the following formulas (1) and (2). ) And the following formula (3).
Formula (1): 2/1 ≦ A / B ≦ 20/1 (mass basis)
Formula (2): 54 mg / L ≦ A ≦ 3000 mg / L
Formula (3): 15 mg / L ≦ B ≦ 300 mg / L
Viscosity at 25 ° C., 1 × a 10 -3 Pa · s~1.5 × 10 -3 Pa · s, heavy metal insolubilization treatment composition according to claim 1.
前記カルシウムイオンの含有量をＡ（ｍｇ／Ｌ）とし、前記鉄イオンの含有量をＢ（ｍｇ／Ｌ）としたとき、ＡとＢとの関係が、下記式（１）、下記式（２）及び下記式（３）の条件を満たす重金属不溶化処理組成物を処理対象土壌に注入することを含む、重金属汚染土壌の修復方法。
式（１）：２／１≦Ａ／Ｂ≦２０／１（質量基準）
式（２）：５４ｍｇ／Ｌ≦Ａ≦３０００ｍｇ／Ｌ
式（３）：１５ｍｇ／Ｌ≦Ｂ≦３００ｍｇ／Ｌ
Including urease-producing microorganisms, urea, calcium ions, and iron ions,
When the content of the calcium ions is A (mg / L) and the content of the iron ions is B (mg / L), the relationship between A and B is expressed by the following formulas (1) and (2). ) And a heavy metal insolubilized treatment composition that satisfies the following formula (3):
Formula (1): 2/1 ≦ A / B ≦ 20/1 (mass basis)
Formula (2): 54 mg / L ≦ A ≦ 3000 mg / L
Formula (3): 15 mg / L ≦ B ≦ 300 mg / L
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