1,087 research outputs found

    Oil spill problems and sustainable response strategies through new technologies

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    Crude oil and petroleum products are widespread water and soil pollutants resulting from marine and terrestrial spillages. International statistics of oil spill sizes for all incidents indicate that the majority of oil spills are small (less than 7 tonnes). The major accidents that happen in the oil industry contribute only a small fraction of the total oil which enters the environment. However, the nature of accidental releases is that they highly pollute small areas and have the potential to devastate the biota locally. There are several routes by which oil can get back to humans from accidental spills, e.g. through accumulation in fish and shellfish, through consumption of contaminated groundwater. Although advances have been made in the prevention of accidents, this does not apply in all countries, and by the random nature of oil spill events, total prevention is not feasible. Therefore, considerable world-wide effort has gone into strategies for minimising accidental spills and the design of new remedial technologies. This paper summarizes new knowledge as well as research and technology gaps essential for developing appropriate decision-making tools in actual spill scenarios. Since oil exploration is being driven into deeper waters and more remote, fragile environments, the risk of future accidents becomes much higher. The innovative safety and accident prevention approaches summarized in this paper are currently important for a range of stakeholders, including the oil industry, the scientific community and the public. Ultimately an integrated approach to prevention and remediation that accelerates an early warning protocol in the event of a spill would get the most appropriate technology selected and implemented as early as possible-the first few hours after a spill are crucial to the outcome of the remedial effort. A particular focus is made on bioremediation as environmentally harmless, cost-effective and relatively inexpensive technology. Greater penetration into the remedial technologies market depends on the harmonization of environment legislation and the application of modern laboratory techniques, e.g. ecogenomics, to improve the predictability of bioremediation

    Sulfate-Reducing Bacteria Community Analysis: ISCO/ISB Coupled Remediation

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    Improved techniques for remediating groundwater systems are required for the more than 500,000 contaminated sites in North America. Many of these sites are the legacy of historical industrial operations, inappropriate disposal practices and accidental releases. The most widely observed contaminant at many of these sites is petroleum hydrocarbons (PHCs). Recently, remediation efforts that involve the sequential application of treatment technologies have gained widespread interest. One specific sequential technology application or treatment train employs the aggressive nature of a chemical oxidation followed by bioremediation for polishing. When persulfate is used as the chemical oxidant its natural degradation by-product is sulfate, an electron acceptor for sulfate-reducing bacteria. Hence in this thesis, the focus is on ways to optimize the mass removal behaviour of a treatment train that involves the use of PHC biodegrading sulfate-reducing bacteria as a bioremediation tool for the ‘polishing’ of a contaminated site. Persulfate was predicted to have a multitude of effects on microbial communities, both positive and negative. It was hypothesized that the production of sulfate would enhance the sulfate-reducing community and subsequently increase biodegradation potential following a persulfate treatment. However, the use of a strong oxidant like persulfate may also have detrimental effects on microbial communities. In order to test this hypothesis, a bench-scale system was implemented to gather data for the analyses of this remediation technique. Microbiological methods and chemical analyses of geochemical parameters were used to examine diversity, richness and abundance of sulfate-reducing communities following persulfate treatments. Initially, the successful generation of anaerobic bioreactors containing an indigenous sulfate-reducing microbial community from a freshwater aquifer was completed and confirmed using colony-PCR. Approximately 3 ppm total PHC was then introduced into the reactors and the microbial community was then allowed to acclimate to the conditions. PHC biodegradation was confirmed (~ 5.7 µg/L/hr). The community was then exposed to two types of oxidants, unactivated and alkaline-activated persulfate. Immediately following exposure, culture-based methods revealed almost complete reduction of the microbial community (≤101 CFU/mL and SRB cells/mL). qPCR on a gene conserved within the sulfate-reducing phylogeny confirmed this reduction. However, by the fourth week of the recovery phase, bacterial counts and target genes rose above pre-treatment levels, indicating enhancement of the sulfate-reducing community following the oxidant exposure(s). However, the recovered community displayed differences in structure and function, as revealed by microbial community fingerprint profiles and a lowered biodegradation potential (~2.7 µg/L/hr). Overall this research illustrated the successful application of a remediation treatment train at a bench-scale level

    Microbial Effects on Repository Performance

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    This report presents a critical review of the international literature on microbial effects in and around a deep geological repository for higher activity wastes. It is aimed at those who are familiar with the nuclear industry and radioactive waste disposal, but who are not experts in microbiology; they may have a limited knowledge of how microbiology may be integrated into and impact upon radioactive waste disposal safety cases and associated performance assessments (PA)

    Subsurface interactions of actinide species and microorganisms: Implications for the bioremediation of actinide-organic mixtures

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    We use high-resolution angle-resolved photoemission spectroscopy to investigate the electronic structure of the antiferromagnetic heavy fermion compound CePt2In7, which is a member of the CeIn3-derived heavy fermion material family. Weak hybridization among 4f electron states and conduction bands was identified in CePt2In7 at low temperature much weaker than that in the other heavy fermion compounds like CeIrIn5 and CeRhIn5. The Ce 4f spectrum shows fine structures near the Fermi energy, reflecting the crystal electric field splitting of the 4f^1_5/2 and 4f^1_7/2 states. Also, we find that the Fermi surface has a strongly three-dimensional topology, in agreement with density-functional theory calculations.Comment: 7 pages, 4 figure

    Biotechnology and Bioengineering

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    Biotechnology and Bioengineering presents the most up-to-date research on biobased technologies. It is designed to help scientists and researchers deepen their knowledge in this critical knowledge field. This solid resource brings together multidisciplinary research, development, and innovation for a wide study of Biotechnology and Bioengineering

    Bioremediation of chemically contaminated soil : extraction/analysis methodology development.

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    Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2002.The efficacies of soil extraction methods, namely, Soxhlet, sonication, agitation, alkaline digestion and the ethyl acetate micro-method, for monitoring soil bioremediation were evaluated using three soil types, Swartland, Rensburg and Hutton, encompassing the mineralogical range prevalent in Kwa Zulu Natal. Phenol, atrazine and the BTEX component of petrol were the molecules used in this study and were extracted under different spiking concentrations, after prolonged ageing times up to 21 days and after changing the composition of the spiking solution. It was concluded that extraction methods must be validated for the specific conditions under which they would be used, taking into consideration, soil type, spiking solutions, moisture content, weathering times and the analyte(s) in question. A preliminary appraisal of atrazine degradation in a Hutton soil was then made under the conditions of sterilized, fertilized/non-fertilized and non-sterilized, fertilized/nonfertilized soils. The predominant pathway of atrazine degradation was deemed to be chemically/abiotically mediated due to the soil pH and the presence of iron and aluminium oxides as well as the high levels of manganese in the soil. The results obtained prompted further study into atrazinecatabolism using soil-slurry reactors, under the conditions of carbon-limitation, nitrogen limitation, carbon/nitrogen non-limitation and carbon/nitrogen limitation. A comparison was made between inoculated and non-inoculated bioreactors. The ability of the indigenous microbial population to return the Hutton soil to its original pristine state was confirmed. The expense of inoculation and culture maintenance could be avoided since carbon and nitrogen supplementation would be as equally effective as inoculation

    100 years of microbial electricity production : three concepts for the future

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    Bioelectrochemical systems (BES) have been explored according to three main concepts: to produce energy from organic substrates, to generate products and to provide specific environmental services. In this work, by using an engineering approach, biological conversion rates are calculated for BES resp. anaerobic digestion. These rates are compared with currents produced by chemical batteries and chemical fuel cells in order to position BES in the energy-market. To evaluate the potential of generating various products, the biochemistry behind the biological conversion rates is examined in relation to terminal electron transfer molecules. By comparing kinetics rather than thermodynamics, more insight is gained in the biological bottlenecks that hamper a BES. The short-term future for BES research and its possible application is situated in smart niches in sustainable environmental development, i.e. in processes where no large currents or investment cost intensive reactors are needed to obtain the desired results. Some specific examples are identified

    Corrective Action Design Report(CADR): Guidance for Leaking Underground Storage Tanks(LUST), Sites Using Risk-Based Corrective Action(RBCA), February, 1997

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    The primary objectives of corrective action in response to a high risk classification are both short-term and longterm. The short-term goal is to eliminate or reduce the risk of exposure at actual receptors which have been or are imminently threatened with exposure above target levels. The long-term goal is to prevent exposure to actual receptors which are not currently impacted or are not imminently threatened with exposure

    Subsurface interactions of actinide species and microorganisms: Implications for the bioremediation of actinide-organic mixtures

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