Required conditions for the wastewater treatment through soil are quantitatively discussed from the kinetic point of view. In order to have satisfactory treatment of wastewater by soil both BOD and hydraulic loadings per unit effective volume of soil and per unit area of land utilized will have to be sufficiently large in order compared with conventional mechanized treatment processes. Under such low loadings; the residence time of wastewater within the effective volume of soil can be kept so long that the BOD can be removed by soil bacteria under their endogenous respiratory conditions. This will avoid the plugging of void in soil by the excess growth of the bacteria, The void fraction of soil will be an important factor which controls the transfer of oxygen consumed by bacterial activity.

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Electrokinetic soil remediation by electroosmosis and ionic migration is restricted to soluble substances. At a higher pH, the soil particles sorb more heavy metals, such as cadmium, than at a lower pH and the precipitation reactions of heavy metals are promoted. Both mechanisms make heavy metals immobile, rendering cleanup more difficult and electrokinetic extraction inefficient. Therefore, the acidification of soils is very important to increase the cleanup efficiencies of heavy metals, such as cadmium by electrokinetic method from contaminated soils. Meanwhile, hexavalent chromium is more mobile and easily soluble. Hexavalent chromium has high solubility in water and exists as chromate, monochromate or dichromate anions depending on the pH of the solutions. This hexavalent chromium is the chemical form requiring remediation. In this study, cadmium and hexavalent chromium transport are predicted with a simple numerical method in which electrical flow is coupled with hydraulic flow, and the sorption process in the soils is induced in the model. The effects of some factors such as electrode configuration, electric field strength and electrode spacing for saturated soils are investigated using this numerical model. The results obtained this study are summarized as follows:
The two-dimensional electrode configurations containing cathode surrounded by three or more anodes rapidly remove cadmium from soils compared with one-dimensional electrode configuration. Meanwhile, in the removal of hexavalent chromium from soils, the two-dimensional electrode configurations containing anode surrounded by three or more cathodes can be effectively utilized compared with one-dimensional electrode configuration. A larger electrode spacing increases the processing time required, and it was also found that a larger electric field strength reduced the processing time required.

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　中国における土壌汚染および土壌保全法整備の現状を分析した。その結果,先進諸国に見られる責任などが明示された,包括的な土壌法制度は整備されていないことがわかった。対策が遅れた理由について,土地の管理責任の曖昧性,また,地方政府と郷鎮企業の依存関係を伴う,強固な地方保護主義の存在などが考えられた。さらには,土壌情報の不足も大きな原因であり,それによる土壌汚染リスクへの認識の低さが土壌保全法整備の遅れをもたらした。この解決策として,土壌情報開示にもとづく管理対策が必要となる。そのためには,中央政府と地方政府が密接に連携した,あらたな土壌管理システムの構築がのぞまれる。

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近年、在韓米軍基地の返還予定地域の残留性有機汚染物質（POPs）を含む複合汚染土壌が確認されている。しかし、韓国ではPOPsに関連した浄化基準および浄化方法が無く、POPsで汚染された土壌の浄化が行われてこなかった。今後、在韓米軍基地の返還に伴う複合的土壌汚染事案が発生する可能性があるため、POPsが検出された汚染土壌の浄化基準および浄化方法を明確に規定することが求められていた。2018年には、土壌汚染の詳細調査が実施され、2019年には、ダイオキシン類を含む複合汚染土壌の浄化のための追加調査と実施計画が立案された。その後、実施計画を基に浄化工事が施工され、2022年には浄化が完了した。今回、キャンプマーケットDRMOサイトのダイオキシン類を含む複合汚染土壌の浄化、土壌パイルを構築して熱伝導加熱による熱脱着工法（IPTD)を用いた汚染

事例を中心に報告する。

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※本記事に抄録はありません。

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トレンチ型の法に関して,簡単なモデルにより,土壌の透水性,保水性および土壌中の酸素の拡散速度より,トレンチへの酸素供給量を推算した。トレンチの形状と,土壌の種類,排水供給量について検討を加えた。透水性の高い土壌ほど酸素の供給に関して有利であり,ローム土等,大孔隙が少ない土壌は法には適さないことが明らかとなった。また,単位幅当りのトレンチの本数を増やすこと,およびトレンチを浅くすることにより,酸素供給量を増やすことができ,単位面積当りの排水処理量を増加し得ることを明らかにした。トレンチ深さを0.10m,単位幅当りのトレンチを5本程度とすることでクロボク土においては約0.2m・d^-1の排水が処理できることが推算された。この方法による用地利用の効率化は,特に集水型の浸透装置の設置において有効であると考えられる。

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In this paper, the simulation model on the evaluation of goods for environmental conscious parchaseing was examined. Linear regression and curvilinear regression methods were used to assess the load of environmental pollution if any correlation existed. First, the equation used for the design ofwater pollution aspects of street surface contaminants and the street runoff as a source of load pollution. Second, the modelling for self-purification of nature to clarify the water pollution by urban runoff from the road surface and drainage pits.
Mathematical simulation of self-purification of nature of water pollution using Monod model for the degradation of organic compounds caused by the contaminants of urban runoff from the road. Finally, the evaluation method for environmental conscious purchasing was used to examine performance data with daily rainfall for the effect of road scavenges before a rainfall. This approach showed that the concept of the model would be useful for the evaluation of environmental protection methods. The reconfirmation of the data and the verification and validation of the model, however, must be done.

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In recent years environmental concerns about subsurface contamination has been pointed out among various fields. Dowa mining CO. Ltd., which opened up mines in the north part of Akita pref. since 1884, has been forced to turn its business field from mining to some other applications because of being weakened its competitive power of mining in the world market. One of the applications for the environmental field started up in 1987 with waste management and metal recycling using the existing facilities and skills of mineral processing and smelting in our company. Around 1990s, as our company has been recognized as providing proper management for all kinds of wastes and reducing environmental risks with highly experienced skills, social demands for treating soils contaminated with heavy metals, volatile organic compounds or petroleum hydrocarbons as wastes have strongly risen up against our company.
In order to respond to those demands, our company has introduced a new concept of "soil remediation" divide the treatment of contaminated soils from waste management. This concept was easily accepted and many kinds of the applications for the remediation were made into practice because our company has contributed to the development of subsurface materials and protection for environmental matters. Thus by applying mining facilities and skills into the new business field of soil remediation, we could accomplish the establishment of this field along with the existing technologies of mining and waste management. In our company soil remediation business can be started with subsurface investigation which is the applied technology of mine probes following to the remediation with our mining concept and technologies including incineration, bioremediation, soil washing, and chemical treatment. Based on the mining technologies described above, we could establish the overall site assessment to treat contaminated soils as “soils” properly.

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The effect of Fe(III) and Ca as coexistent elements on the extraction of Pb from contaminated soils with the biodegradable chelating agent [S,S]-ethylenediaminedisuccinic acid (EDDS) and the low biodegradable chelating agent ethylenediaminetetraacetic acid (EDTA) was investigated as a series of studies for their applicability for the removal of Pb from contaminated soils by soil washing and electrokinetic processing. The results obtained in this study are summarized as follows:
The extraction of Pb with EDTA is suppressed by Ca as coexistent elements at the pH above 7 and by Fe(III) as coexistent elements at acidic region. Meanwhile, the extraction of Pb with EDDS has no effect of Ca at the wide pH range. However, the extraction of Pb with EDDS is significantly suppressed by Fe(III) at the wide pH.

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Restoration of contaminated soils to an environmentally acceptable condition is important. Various methods currently used have advantages and limitations in remediating contaminants in soils. In fact, most successful in situ remediation technologies are restricted to soils with relatively high hydraulic conductivity and can not be used for fine-grained deposits. One of the newer techniques in soil remediation is a method based on electrokinetic phenomena in soils. Electrokinetic soil remediation is an effective in situ separation and removal technique used for extraction of heavy metals and some organic compounds from fine-grained soils. The technology uses electricity to affect chemical concentrations and water flow through the pores of soils.
In the present study, the distributions of cadmium in the electrokinetic processing of kaolinite under the condition of constant applied voltage are predicted using a theoretical model that incorporates equilibrium chemistry and the results are compared with experimental findings. The results obtained in this study are summarized as follows:
The distributions of pH and cadmium simulated by the model show relatively good agreement with experimental results. The steepness of the pH jump and its influence on the distribution of cadmium are clearly seen. Cadmium accumulates in the region of the pH jump to the cathode. As a consequence of the focussing of cadmium in the region of the pH jump to the cathode, the decrease in the volume of soil to excavate from the site is advantageous. From experiments, it was also found that the progress of electrokinetic processing of cadmium could be grasped to a certain extent by monitoring the local voltage and the current density.

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地下水汚染に対して法的な措置が必要とされる場合は、地下水利用の条件(水質汚濁防止法、土壌汚染対策法に示される4項目)に該当する場合に限られる。しかし、地下水利用の条件に該当しない場合であっても、周辺への拡散、一般環境の保全としての取り組みから、地下水の封じ込め対策又は浄化対策を実施することが望ましい。
本件では、土壌汚染対策は法的に実施する状況にあることを前提とし、望ましい地下水環境を保全する目的から自主対策として地下水浄化対策を実施する場合、浄化対策を選定する方法を示すとともに、浄化状況の検証について考察するものである。

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土壌汚染は，高度経済成長により我々が享受してきた豊かな生活の代償として今深刻な社会問題となっている。なかでも，油による土壌汚染が最も多く，その対策が求められている。これは，油が安価でハンドリング性がよく，エネルギー密度が高いなどの優位性から，燃料や洗浄剤として大量に消費し大量に廃棄されてきたことに起因している。筆者らは，油汚染土壌を加熱することにより油を気化蒸発させて土壌の浄化を行い，さらに，土壌から気化蒸発した油を酸化分解することにより排出ガスの無害化をはかる油汚染システムを開発した。本研究では，新たに開発した油汚染システムの概要とその浄化性能について検討している。

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In Application of electrokinetic soil remediation to the heavy metals contaminated soils, the acidification might cause dissolution of part of the solid matrix, and so it is desirable to perform the soil treatment at neutral pH. However, the solubility of most heavy metals is significantly reduced at elevated pH values. The solubility of metals can be enhanced by adding reagents that form metal complexes. Apart from efficacy as metal extractants, complexing agents need also to be rated for safety of use. Biodegradability is of importance because treated soils always contain residual agents that may, upon soil reuse in the field, result in actual metal mobilization and transport to groundwater. It appears therefore essential for these residual agents to be rapidly biodegraded. This is even more important for in-situ soil flushing operations. In this research, the biodegradable chelating agents [S,S]-ethylenediaminedisuccinic acid (EDDS) and N,N-dicarboxymethyl glutamic acid (GLDA) were investigated for their applicability for the removal of lead from soils by electrokinetic processing. The removal efficiency of lead from soils was improved with increase in the concentration of EDDS and the applied electric field strength. It was also found that the concentration of EDDS has a strong effect on the removal efficiency of lead from soils compared with the electrical field strength at the range from 10 V and 20 V. And also, the removal efficiency of lead using platinum-coated titanium used as electrodes increased compared with graphite and iridium dioxide-coated titanium as electrode. Meanwhile, the removal efficiency of lead with GLDA was superior to that with EDDS. However, the high viscosity of GLDA significantly affected the removal efficiency of lead.

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我が国において，都心部における土地有効利用の面から汚染地盤を修復して再利用することが重要な課題となっている。汚染地盤を修復する方法は各種存在するが，それぞれの手法において浄化可能な汚染物質や適用範囲が異なる。修復作業においては，適した工法を選択することで環境負荷と経済性に優れた浄化工事が可能となるため，その計画ではそれぞれの特徴や特性を把握することが必要である。本研究では，筆者らが開発した熱脱着処理によるシステムを実地盤の汚染土壌の浄化工事に対して適用し，その浄化特性と浄化機構を明らかにした。また，熱脱着処理による複合汚染や重金属汚染への適用範囲の拡大の可能性についての検討を行った。

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