Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1984. / Includes bibliographical references (leaves 54-55).

Thesis (Ph. D., Civil Engineering)--University of Idaho, April 2008. / Major professor: Steven Porter. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: chemical oxidation; In-Situ; TCE. Includes bibliographical references (leaves 50-53).

Nanoscale zero-valent iron (NZVI) particles were encapsulated in calcium alginate capsules for application in environmental remediation. TCE degradation rates for encapsulated and bare NZVI were similar indicating no adverse effects of encapsulation on degradation kinetics. Microorganisms were separately encapsulated and used along with encapsulated NZVI and co-encapsulated in calcium alginate capsules. Batch experiments were performed to test the efficacy of the combined iron-Pseudomonas sp. (PpF1) system. The combined system removed 100% TCE over the first three hours of the experiment followed by 70% TCE removal post TCE re-dosing. Complete reduction of TCE was achieved by NZVI between 0-3 h and the second phase of treatment (3-36 h) was mostly achieved by microorganisms. Experiments conducted with co-encapsulated NZVI-D.BAV1 achieved 100% TCE removal. During the first three hours of the experiment 100% TCE removal was achieved by NZVI, and 100% removal was achieved post re-dosing where D.BAV1 accomplished the treatment. / Department of Civil Engineering, North Dakota State University

Trichloroethylene (TCE) was widely used as an industrial solvent and degreasing agent for most of the twentieth century. It is now a widespread groundwater contaminant. Phytoremediation may be a cost-effective cleanup method for TCEii contaminated soils and groundwater. Studies of environmental TCE fate are complicated by its volatility. The literature repons both significant and insignificant plant uptake of TCE. Conflicting findings may be due to differences in exposure level, conditions, and duration of the studies, or to experimental artifacts from laboratory systems. This research quantified plant uptake and volatilization of TCE using a unique laboratory system. Hybrid poplar trees were exposed to 1 or 10 ppm TCE over a 43-d period. [14C]TCE was added to four high-flow, aerated, hydroponic plant growth chamber systems designed to provide high mass recoveries, an optimal plant environment and complete separation between foliar and root uptake. Transpiration stream concentration factors (TSCFs) for TCE, calculated from total [14C]TCE in shoot tissues plus phytovolatilized 14C, were 0.11 for two 1 ppm treatments and 0.15 for a 10 ppm treatment with roughly 25% attributed to phytovolatilization. Though extending study duration from 26 to 43 d resulted in accumulation of more mass of 14C in plant tissues, it had no effect on TSCF. These TSCF values are much lower than other published experimental values and values predicted by a theoretical relationship between TSCF and octanol-water partition coefficient. The TCE metabolites trichloroethanol (TCEt), trichloroacetic acid (TCAA), and dichloroacetic acid (DCAA)were identified in plant tissues of the 10-mg/L treatment. Hybrid poplar uptake ofTCAA and TCEt was quantified using a simpler aerated hydroponic system. TSCF values were calculated based on extractable parent compound in shoot tiss ues. TSCF for TCEt was < 0.01. Presence of TCAA in hydroponic solution and in leaf and root tissues indicated transformation of TCEt to TCAA. TSCF for TCAA was < 0.03 and decreased with increasing exposure concentration. TSCF also decreased under oxygen-limited root-zone conditions. Presence of DCAA in leaf and root tissues indicated transformation ofTCAA to DCAA. Transformation of parent compound, coupled with low extractability, may contribute to low TSCFs.

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 101-116). Also available on the World Wide Web.

Thesis (M. Env. St.)--University of Adelaide, 1984. / Dated 1983. Includes bibliographical references (leaves 174-181).

Thesis (Ph.D. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references (leaves 242-259).

Remediation of trichloroethylene (TCE) and other chlorinated solvents is of great concern due to their toxicity and their persistence in the environment. Iron has been used extensively in the past decade as a subsurface reactive agent for the remediation of dense, nonaqueous-phase liquids (DNAPLs). Permeable reactive barrier walls (PRBW) have been installed at many sites around the country to treat contaminated plumes resulting from the presence of DNAPL pools. The use of zero-valent metals, such as iron, to effectively reductively dechlorinate DNAPLs has been employed as the reactive material in these PRBWs (Gillham et al., 1993). However, limited work has been conducted to compare the kinetics of TCE degradation related to various manufacturing sources of iron and the pretreatment the iron receives prior to subsurface installation. Determination of iron reactivity through kinetic studies makes it possible to compare different types of iron and the effects that pretreatment has on reactivity. This research utilized rate studies, scanning electron microscopy, and BET surface area analysis for iron particles that were obtained from several sources. Peerless Metal Powders and Abrasive, Inc., Connelly-GPM, Inc., and Alfa Aesar Inc., produced the iron particles using various manufacturing techniques, and nanoscale iron was synthesized in our laboratory. By utilizing zero-headspace batch vial experiments and gas chromatography, changes in TCE concentration were determined. The data obtained produced linear first order rate plots from which dehalogenation rate constants were obtained. The rate constants were normalized by iron mass, solution volume, and surface area. The pretreatment techniques employed in this study, including ultrasonication and acid washing, demonstrated a beneficial effect by removing oxide precipitates from the iron surface, thus increasing the reactivity of the iron. Mass loading studies revealed how physical factors, associated with the experimental setup, could influence reaction rates. Surface area studies confirmed that the smaller iron particles, such as the nanoscale iron, have a greater surface area per unit mass. The large mass and volume normalized rate constant, kMV, obtained for the nanoscale iron was a result of this high surface area. However, the calculated surface area normalized rate constant, kSA, for the nanoscale iron was significantly lower than those for the granular iron samples tested. It was concluded that differences in surface area normalized rate constants, between different iron particle types, could be attributed to inherent characteristics of the iron, such as composition and crystal structure.

No description available.