Strength Property and Pollutant Elution Characteristics of Contaminated Sediment Treated by Cement-Mixing and Mechanical Dehydration

本論文では，重金属，トリブチルスズ(TBT)およびトリフェニルスズ(TPT)を含む汚染粘土を対象に，固化材等を混合し高圧で機械脱水を行う手法(以下，高圧脱水固化処理とよぶ)を用いて，汚染粘土の強度特性の改善および汚染粘土中に含まれる有害物質の溶出低減効果を調べた．得られた結論をまとめると以下のようになる．(1)固化材添加率30％および脱水圧力10MPa以上の作製条件において，10MPaを超える一軸圧縮強度を有する固化処理土を作製できる．(2)高圧脱水固化処理により，汚染粘土からの重金属の溶出を環境基準値以下に低減できる．(3)高圧脱水固化処理後の汚染粘土からのTBTとTPTの溶出量は，アルカリ性領域において，溶媒のpHの指数関数として表すことができる．Authors have developed a technique, called the cement-mixing and mechanical dehydration (CMD), as one of waste recycling and pollutant stabilization techniques. In order to investigate the strength properties and elution characteristics for contaminated sediments containing heavy metals, tri-butyl tin (TBT) and tri-phenyl tin (TPT), unconfined compression test and a series of elution tests were performed for contaminated sediments treated by the CMD. The main conclusions obtained form this study are as follows; 1) CMD is effective for increasing the unconfined compressive strength of contaminated sediments. 2) Heavy metals eluted from contaminated sediment treated by CMD can be satisfied with the Japanese national environmental quality standard. 3) Elution of TBT and TPT can be expressed by an exponential function of the potential of hydrogen, pH, in alkaline pH range