No description available.

No description available.

Bibliography: leaves 116-127.

Bibliography: leaves 177-191.

Pentachlorophenol (PCP) is a biocide used by the NZ forestry industry until 1988. Its use was discontinued due to its toxicity to humans and animals. White-rot fungi have been shown to degrade PCP in laboratory and field trials. New Zealand native white-rot fungi were screened to identify organisms suitable for the clean up of PCP contaminated sites. Four criteria were used for the screening: fungal growth at different temperatures, PCP and creosote resistance and PCP degradation in standard liquid medium. Twenty isolates were identified as potentially useful from over 200 that were screened. One unique isolate, Trametes sp. HR577, was chosen for intensive study because it produced the well known laccases previously described from other PCP-degrading white-rot fungi. The white-rot isolate HR577 was assigned to the genus Trametes based on morphological characteristics and gene sequencing studies. The latter showed that the partial laccase gene sequences from Trametes sp. HR 577 had high sequence homology to laccases from other Trametes species, especially T. versicolor and T. villosa. Two laccase isozymes, designated L1c and L2, were purified from Trametes sp. HR577. These isozymes had similar biological properties to other Trametes species laccase isozymes. Both isozymes had a relatively high temperature optima, however, they were not very stable at elevated temperature. The dependence of laccase on dissolved oxygen for catalysis was demonstrated for isozyme L2. Laccase activity was severely inhibited in the absence of dissolved oxygen. This could be restored by reoxygenation into the assay system. Whole cultures of Trametes sp. HR577 grown in liquid culture removed up to 76% of PCP after 72 hours. PCP removal was mostly due to degradation rather than adsorption of PCP to fungal mycelium. Addition of purified and crude laccase isozymes (100 U mL-1) did not enhance PCP degradation. 6-15% of PCP was removed from solutions containing solely purified isozyme L1c or L2 in acetate buffer over 72 hours. Addition of ethanol or the laccase mediator compound 2,2' azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) resulted in increased PCP disappearance from purified laccase cultures. These studies show that the white-rot Trametes sp. HR577 has potential to be used for the clean up of PCP contaminated sites in NZ.

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

<p>The disposal of combustible wastes by incineration is a controversial issue that is strongly debated by both scientists and environmental activists due to the resulting emissions of noxious compounds, including (<i>inter alia</i>) polychlorinated dibenzo-<i>p</i>-dioxins (PCDDs), dibenzofurans (PCDFs), heavy metals and acid gases like sulfur dioxide. Currently available air pollution control devices are capable of effectively cleaning flue gases, and PCDD/F emissions to air from modern municipal solid waste (MSW) incinerators are low. However, the PCDD and PCDF end up in ash fractions that, in Sweden, are usually deposited in landfills.</p><p>The European Union has recently set a maximum permitted total concentration of 15 µg TEQ/kg for PCDD/F species in waste. Fly ash from municipal solid waste (MSW) incineration containing PCDD/Fs at concentrations above this limit will have to be remediated to avoid disposing of them in landfills; an expensive and environmentally unfriendly option. Therefore, effective, reliable and cost-effective methods for degrading PCDD/F in fly ash are required, and a better understanding of the behavior of PCDDs and PCDFs during thermal treatment will be needed to develop them.</p><p>In the studies this thesis is based upon both the formation and degradation of PCDDs and PCDFs in ashes from MSW incineration were studied.</p><p>The main findings of the investigations regarding PCCD/F formation were:</p><p>- The concentrations of PCDD and PCDF in fly ash increased with reductions in the temperature in the post-combustion zone.</p><p>- The homologue profile in the ash changed when the temperature in the post-combustion zone changed.</p><p>- The final amounts of PCDD and PCDF present were affected by their rates of both formation and degradation, and the mechanisms involved differ between PCDDs and PCDFs.</p><p>The main findings from the degradation studies were:</p><p>- The chemical composition of ash has a major impact on the degradation potential of PCDD and PCDF.</p><p>- The presence of oxygen during thermal treatment can enhance the degradation of PCDD and PCDF.</p><p>- Thermal treatment is a viable option for degrading PCDD and PCDF in ashes from MSW.</p><p>- Shifts in chlorination degree occur during thermal treatment.</p><p>- Rapid heat transfer into the ash is a key factor for ensuring fast degradation of PCDD and PCDF.</p><p>- Degradation of other chlorinated organic compounds, e.g. PCB and HCB, also occurs during thermal treatment of ash.</p><p>- Reductions in levels of PCDD and PCDF were not solely due to their desorption to the gas phase.</p><p>- Differences between the behavior of 2378-substituted congeners of PCDD and PCDF and the other congeners during thermal treatment were observed.</p><p>- Differences in isomer patterns of both PCDD and PCDF were observed between the ash and gas phases after thermal treatment at both 300 and 500 oC.</p><p>Overall, the results show that the formation and degradation mechanisms of PCDDs differ substantially from those of PCDFs. Thus these groups of compounds should be separately considered in attempts to identify ways to reduce their concentrations.</p>

<p>The concept of the photographic truth has had a special status for almost 200 years. Yet with the emerge of digital technology and especially digital photography there has been a loss of the particular connection photography has had in reference to reality. The aim of this study is to see in what ways digitalization has affected the credibility of photography from the perspective of professionals in the field of photography. The digital technology that has enabled the large-scale manipulation of photographies is not, however, the main reason for the decreased credibility of photography. The ongoing discussion about the available possibilities concerning digital imagery and manipulation has had a far more powerful effect on the concept of the photographic truth. Along with these possibilities a post-photographic photograph has seen the light of day. We discuss further some credibility problems caused by this new phenomenon; i.e. the post-photographic photographies can’t be considered to have the same status as the traditional photographies when it comes to presenting reality truthfully. We approached the subject through theory studies and methodically through personal interviews.</p><p>Key words: credibility, digitalization, manipulation, remediation, reality, noeme, and the post-photographic era.</p>

<p>This Master Thesis presents TMVOC simulations of a NAPL-spill (non-aqueous phase liquid) and following pumping remediation. TMVOC is a simulation program for three-phase non-isothermal multicomponent flow in saturated-unsaturated heterogeneous media. The models presented are based on an actual remediation project. The aim of the thesis was to study if the historical development of the NAPL-spill could be simulated and how long time the pumping remediation would take. A 3D-model and a radially symmetric cylindrical model were created.</p><p>A large effort of the work done was in taking the complex TMVOC model in use and modifying it for the problem at hand. Therefore, the numerical results of the simulations should be considered as preliminary and as forming basis for future studies.</p><p>The results from the spill simulation and historical pumping simulation indicated that the spill volume could be less than the estimated 1400 m³, perhaps around 700 m³, assuming a leakage time of 30 years.</p><p>The historical pumping simulation of a 700 m³ diesel spill showed good agreement with measured values for some wells, but overestimated the recovery in other wells. The overestimation could be due to the fact that the 3D-model did not take seasonal changes in the groundwater level into consideration. Also, the model did not account for any heterogeneity or compartmentalization in soil material properties that could explain the differences between the wells. </p><p>Assuming the same spill of 700 m³, future pumping was simulated. The results from these simulations indicated the remediation time to be long due to fast decreasing mobility of the NAPL phase. The NAPL flow rate to the wells was halved in a couple of years. Much of the NAPL was distributed over a large area at near residual saturation with the highest NAPL saturation found at the opposite side of the pumping wells in the model.</p><p> </p><p>Future simulation studies should address the effect of discretization as well as the effect of uncertainties in material properties e.g. conductivity, residual NAPL saturation and soil heterogeneity.</p>