No description available.

No description available.

Bibliography: leaves 116-127.

Bibliography: leaves 177-191.

The ever-increasing detection of harmful organic and inorganic compounds in habitable areas throughout the world has led to mounting research into applications and techniques for the treatment of contaminated soils, surface and groundwaters, and chemical and industrial wastewaters. Chemical oxidation technologies, in particular Fenton-based remediation systems, have exhibited considerable potential for the effective treatment and remediation of such contaminated waters and soils. The use of Fenton-based oxidation systems for the treatment of contaminated waters and wastewaters warrants the development of kinetic models capable of accurately simulating system behaviour. In this thesis, the kinetics of Fenton-mediated oxidation systems and kinetic models based on its governing reaction mechanism are investigated in order to highlight those parameters and conditions that effect Fenton chemistry and oxidation performance, and to demonstrate the application of such kinetic models to design and improve treatment systems. Experimental and simulated data describing the oxidation of formic acid by Fenton's reagent at low pH (3 to 4) and under a variety of initial conditions, operating regimes, and solution environments supports a proposed reaction mechanism that nominates the hydroxyl radical (OH) as the active oxidizing intermediate in Fenton-based oxidation systems. Laboratory experiments demonstrate that formic acid oxidation is inhibited in the presence of oxygen, and model simulations of these systems reveals that such behaviour is due to the effect organic radical intermediates and/or by-products have in assisting or hindering the redox cycling of the catalytic iron species. The critical role that iron redox cycling plays in affecting oxidation performance is further highlighted by experimental and simulated studies at alternate pHs and using different target organics, including those that react directly with iron in a redox capacity. Experiments at pH 4 reveal an increase in the redox cycling of iron and improved oxidation performance compared to pH 3 as the higher pH favours the superoxide radical, a stronger reductant than the hydroperoxyl radical that predominates at pH 3. Other laboratory and modelling studies on the Fenton-mediated oxidation of certain aromatic compounds highlight the manner in which quinone and quinone-like compounds, being added directly or generated as oxidation by-products, can improve oxidation performance via redox reactions with iron. Further simulations reveal the type of practical design and operating information kinetic models can provide for treatment processes, though it is noted an appropriate understanding of the oxidation mechanism of the target species is necessary for the accurate application of the model.

Bibliography: leaves 177-191. / xxi, 191 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil and Water, 2001

The Hanford nuclear reservation in Washington state was initially created during World War II for the production of plutonium to be used in atomic bombs. A perceived need for a large increase in the number of nuclear weapons spurred expansions in production facilities at Hanford through the 1960's, and production was continued through the mid 1980's. The production process included irradiation of uranium fuel in reactors followed by chemical separation of the plutonium from the other fuel constituents, and finally transformation of plutonium nitrate to plutonium metal. The various steps in the process produced large amounts of radioactive as well as chemical hazardous waste. Some of this waste was released to the environment either through deliberate disposal methods or by leaks in transfer and storage systems. As a result, the soil at many areas of Hanford is contaminated to a point at which it would be unsafe for human contact for more than a short period of time. The current focus of efforts at Hanford is cleanup of the environment as well as decommissioning of the facilities. As part of the cleanup process, future land use must be determined which will then affect the scale of the remediation effort. The proposed land use will determine the residual contamination which will be left after all remediation is complete and access is allowed to the site. This document details the process for determining the residual contamination levels associated with various land use options. Some possible land use options are explained in the form of exposure scenarios. These scenarios give data in the form of exposure factors which describe the possible exposure level of an individual to contaminated media. Once the exposure factors are determined, they can be used in the equations outlined in the Hanford Site Risk Assessment Methodology to calculate preliminary remediation goals. These goals are presented as contaminant concentrations in environmental media which are the maximum allowable in order to meet regulatory limits. The limits are expressed either as a risk for carcinogens, or as a hazard quotient for non-carcinogens. / Graduation date: 1997

This research was aimed to investigate the enhancement of electrokinetic (EK) remediation arsenate-contaminated soil by permeable reaction barrier (PRB). All experiments, which experimental parameters included the position, materials, and quantity of PRB, processing fluid types, potential gradients, and treatment time, were conducted in two types of EK systems. One was Pyrex glass cylindrical cells with dimension of 4.2 cm (£r) ¡Ñ 12 cm (L) and the other was a small pilot-scale modulus with dimension of 36cm (L) ¡Ñ18cm (W) ¡Ñ18cm cm (H). The PRBs were composed of four kinds of reaction materials, which included commercial zero valent iron (Fe(0)C), manufactured zero valent iron (Fe(0)M), commercial hydrous ferric oxide (FeOOHC), and manufactured hydrous ferric oxide (FeOOHM), mixed with ottawa sand in a ratio of 1:2,respectively, and installed in the anode, middle, and cathode side of the EK systems. For 5-day EK cylindrical cell tests, the results showed that the PRB installation would result in a lower electroosmosis permeability (Ke) and a higher removal efficiency of arsenate. The arsenate removal efficiency of EK system with PRB was in the range of 43.89-70.25%, which was 1.5~2.6 times greater than that without PRB, and the value of Ke was in the range of 4.30-12.61¡Ñ10-6 cm2/V-s. The soil pH after EK/PRB treatment was much closer to natural and more arsenate was collected in the anode reservoir. Moreover, the remediation performance of FeOOHC as PRB materials was much better than other materials. For EK pilot-scale modulus tests, it was shown that the removal efficiency of arsenate was effectively enhanced as improved experimental parameters and, however, led to increase the treatment cost. In EK modulus without PRB, the removal efficiency of arsenate, elctroosmosis permeability, and energy consumption were 27.76%, 3.30-5.39¡Ñ10-6 cm2/V-s, and 1724.81 kWh/m3, respectively. Furthermore, the treatment cost was NT 9583/m3. As increasing treatment time, graphite electrode, potential gradient, and quantity of PRB materials, the removal efficiency of arsenate increased to as high as 45.11-71.22% and the treatment cost also increased up to NT 24,800-57,730/m3. As investigated the binding form of arsenate with soil after EK/PRB treatment, it was found that the arsenate ¡Vsoil binding forms of Fe-Mn oxide bound, organically bound, and residual in the soil section behind the PRB were much easier transformed to the forms of exchangeable and carbonate bound. The transformation rate reached as high as 72.5% and it increased with treatment time. However, the Fe-Mn oxide bound was still the main binding form, 61.6-81.6%, in the soil section prior to the PRB. The removal mechanism of arsenate contaminated soil remediation was dominated by electromigration, electrolysis, and electroosmosis in EK system without PRB. And, in EK/PRB system, the removal of arsenate from soil was mainly resulted from adsorption rather than redox reaction by PRB. To sum up, the PRB can effectively enhance the electrokinetic remediation of arsenate contaminated soil by choosing the right PRB materials and operation parameters.

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Life cycle assessment of soil remediation options:Study of options at Norrbyskär - which alternative has the least climate impact?  The purpose of this report was to make a life cycle assessment (LCA) to compare four suggested options for soil remediation at Norrbyskär, Umeå. The question formulation was to find out which option that had the least climate impact depending on the aim of the remediation. Main focus of the study was emissions of CO2 from transportation and machine work for each remediation option. The LCA was a screening and presented a good overview for the results. What sets the four remediation options apart is the amount of soil that is processed for each option. The LCA was performed according to the standards ISO 14040:2006 and ISO 14044:2006. Calculations in the report was performed with the LCA-software SimaPro and general data from EcoInvent. The results showed that the total emissions from each soil remediation option varied between 310 and 590 tonnes carbon dioxide equivalents (CO2e). The option that only included covering of the contaminated area with new soil had the least emissions and the option that included excavation and filling with new soil had the highest emissions. Both options do not fulfill the same goals in the end, though. One conclusion is that the more extensive remediation is the greater is the climate impact.