摘要
土壤修复主要通过将受污染土壤进行挖掘和填埋,这种方法在进行大量位点修复时不太切合实际,因此要选择其它棕地(brownfield)修复方法。本研究介绍了评估受铜铬砷(CCA)污染土壤采用含铁(Fe)爆破砂(BS)或嵌氧颗粒(OSG)处理后的化学稳定过程。就工业尺度下混合改良物的可行性和在不同氧化还原条件下的稳定效率对这种稳定技术进行了评估。在野外自然条件下,采用1m^3测渗计调查了这种稳定性并在实验室(10L)对氧化还原条件的效应进行了评估。结果表明改良物的添加率最低时(0.1%和1%)化学计量中还有足够的铁,但是不管在野外还是实验室都是采用高添加率的改良物(8%和17%)效果较好。铁和混合物的颗粒大小会影响稳定效率。厌氧条件的发展(模拟自水饱和度)会提高砷(As^(3+))的份额,因此增强了砷的迁移能力。在有氧条件下,采用高浓度OSG提高了孔隙水中镍(Ni)和铜(Cu)的浓度,但是在厌氧条件下,与未作处理的土壤相比,砷的淋溶率降低了,而镍和铜的淋溶并不是关键的。所处理土壤的最终目的决定了改良方案,也就是说,对于在厌氧条件下填埋的土壤,OSG浓度为10%较合适。也可以在有氧条件下将1%的BS与土壤混合,置于填埋区上层或者棕色地块(brownfield site)原处。另外从长期来看,采用BS处理似乎比用OSG处理效果要好。
Lars Lovgren,Solomon lesraliaet ana Jurate K.umpiene Remediation mainly based on excavation and burial of the contaminated soil is impractical with regard to the large numbers of sites identified as being in need of remediation.Therefore,alternative methods are needed for brownfield remediation.This study was conducted to assess a chemical stabilization procedure of CCA-contaminated soil using iron (Fe)-containing blaster sand (BS) or oxygen-scarfing granulate (OSG).The stabilization technique was assessed with regard to the feasibility of mixing ameliorants at an industrial scale and the efficiency of the stabilization under different redox conditions. The stability was investigated under natural conditions in 1-m3 lysimeters in a field experiment,and the effect of redox conditions was assessed in a laboratory experiment (10 L).The treatments with high additions of ameliorant (8% and 17%) were more successful in both the laboratory and field experiments,even though there was enough Fe on a stochiometric basis even at the lowest addition rates (0.1% and 1%).Theparticle size of the Fe and the mixing influenced the stabilization efficiency.The development of anaerobic conditions,simulated by water saturation,increases the fraction of arsenic (AsIII) and,consequently, As mobility.The use of high concentrations of OSG under aerobic conditions increased the concentrations of nickel (Ni) and copper (Cu) in the pore water. However,under anaerobic conditions,it decreased the As leaching compared with the untreated soil,and Ni and Cu leaching was not critical.The final destination of the treated soil should govern the amendment choice.
