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Abstract.The study investigated the potential of nanoscale Ni/Fe bimetallic particles reduction for carbon tetrachloride (CT) and tetrachloroethene (PCE). BET specific surface areas of the laboratory synthesized Ni/Fe (2% wt.) particle, with diameter on the order of 20-60nm, was approximately 52.61m 2 /g. Batch studies demonstrated that rapid transformations of PCE and CT were achieved with nanoscale Ni/Fe particles. The degradation process appeared to be pseudo-first-order. Values of the surface area normalized rate coefficients (K SA ) of PCE and CT for the reaction with nano Ni/Fe were 2.068mL/(m 2 ·h), 10.08mL/( m 2 ·h), respectively. This indicated that the degradation rate of CT was about 5 times larger than that of PCE under comparable environmental condition. Significant amounts of DCM were detected for the reaction with CT unlike the PCE transformation where ethane was the only end-product, amount to 103% of the initial PCE carbon. Both DCM (~15%) and methane (~27%) were the major end products for CT reaction. Based on the rapid rate of degradation and no or less chlorinated byproducts, the nanoscale particles technology offered great opportunities for both fundamental research and technological application for remediation of contaminated ground water.

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An illegal dumping site located in Ping-Tung County, Taiwan was selected as the case study site. For the site remediation and decision-making purposes, illegal waste dumps need to be identified before the application of remedial tasks. However, traditional investigation via soil gas/soil sampling is not able to detect buried wastes or containers in a cost-effective and time-efficient way. In this study, a ground-pentrating radar ͑GPR͒ system was utilized to locate the buried wastes under a central frequency operation of 300 MHz. This paper was aimed at ascertaining the feasibility of GPR application on this case study. Based on the results of GPR detection, several highly suspected regions of buried waste were delineated through congregating the sections of abrupt intensive GPR reflectance on each walkpath. Subsequently, the suspected regions were subjected to field sampling as well as laboratory analysis of volatile organic compounds, semivolatile organic compounds, and heavy metals. With the aid of GPR detection, several bags of fly-ash-like dust were unearthed in hot spot region. According to lab data of sample analysis, soil samples from hot spot area were abundant in zinc and lead, which were closely associated with the unearthed fly-ash-like dust. The results of an integrated approach of site investigation in an uncontrolled dumpsite were presented to offer suitable information for those who intend to utilize the GPR application on the masterpiece of hazardous waste management.

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In this study, nanoscale zero-valent iron (NZVI) particles were synthesized and utilized to integrate with surfactant and electrokinetics for the remediation of perchloroethylene (PCE). The average particle diameter and specific surface area of the lab-synthesized iron particles were 109.3 nm and 129.7 m 2 g -1 , respectively. Experiments were performed in a glass sandbox to simulate the transport and degradation of PCE in the aquifer. The results of the transport tests revealed that the PCE concentrations at the bottom layer was higher than those at the mid and upper layers, and that the surfactant Tween 80 showed its conspicuous mobilization for PCE in the aquifer. As the results of the degradation tests showed, NZVI activity could be promoted by electrokinetics that enhanced the remediation performance of PCE contaminated groundwater by the NZVI reactive barrier. Chlorinated byproducts were not detected during the degradation tests, that is, PCE was completely dechlorinated by NZVI in the reactive barrier. The information collected from this study will be useful for further application of the NZVI reactive barrier system to remediate the aquifers contaminated by the chlorinated solvents.