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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
431

Hazardous air pollutants from the waste incineration industry : formation mechanisms, distribution characteristics, and potential environmental risks

Wang, Chen 07 September 2020 (has links)
In this study, the formation mechanisms, distribution characteristics, and potential environmental risks of hazardous air pollutants from industrial-scale waste incineration processes were investigated. First, to clarify the dominant formation mechanism of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) in a hazardous waste (HW) incinerator, three tests were designed by adding different precursors in phenol-containing raw materials. With the addition of p-dichlorobenzene, PCDD/F levels at the quenching tower outlet were ten times higher than levels observed at the inlet. This indicates that the quenching tower failed to suppress the formation of PCDD/Fs and surface-mediated precursor reaction is the dominant formation mechanism in low-temperature stages. Besides, adsoprtive memory effect in air pollution control devices (APCDs) also led to high PCDD/F emissions. These findings suggest that to control PCDD/F emissions, strict regulation of chlorine contents in feed materials and frequent cleaning of APCDs are necessary. Meanwhile, single particles and solid residues were collected from the same HW incinerator. Morphologies and elemental compositions of particles in flue gas and indoor air were characterized by transmission electron microscopy-energy dispersive X-ray spectrometry (TEM-EDS). Eight types of single particles were classified, as organic, soot, K-rich, S-rich, Na-rich, Fe-rich, mineral and fly ash particles. The heavy metal partitioning behavior study suggested that Hg, Cd and Pb were mainly enriched in fly ash through evaporation, condensation, and adsorption; while Cr, Cu, Mn, and Ni were mostly remained in the bottom ash due to their low volatilities. In addition, the study also investigated environmental behaviors of certain characteristic pollutants. Thrity-two soil samples surrounding a cement plant co- processing HW were collected and analyzed for the presence of 16 polycyclic aromatic hydrocarbons (PAHs) and 12 heavy metals. Ten samples were selected for PCDD/Fs analysis. The highest concentration of PCDD/Fs occurred 1200 meters downwind from the cement plant. Levels of ∑16 PAHs ranged from 130.6 to 1134.3 μg/kg in soil. Source identification analysis suggested that the cement plant was the most likely source of PAH contamination. The concentrations of Cd and Hg were on average two times and six times higher than background values, respectively. Both incremental lifetime cancer risk model (ILCR) for PAHs and potential ecological risk index (RI) for heavy metals indicate potential risks to the population and the environment surrounding the cement plant. Last, to identify whether waste incineration is a major source for airborne environmentally persistent free radicals (EPFRs), tree leaf samples were collected from 120 sites surrounding four waste incinerators and one urban area. EPFR concentrations on leaves ranged from 7.5 × 10 16 to 4.5 × 10 19 spins/g. For the 10 N.D. samples, they were all collected from areas inaccessible by vehicles. Although previous work has linked atmospheric EPFRs to waste incineration, the evidence in this study suggests that vehicle emissions, especially from heavy-duty vehicles, are the main sources. According to our estimation, over 90% of the EPFRs deposited on tree leaves might be attributed to automotive exhaust emissions, as a synergistic effect of primary exhausts and degradation of aromatic compounds in road dust
432

Transporting and Disposing of Wastewater from North Dakota Oil Producers

Yin, Qingqing January 2012 (has links)
North Dakota’s oil boom is aided by a new technology, fracking. But this technology implies large amounts of wastewater. The methods of dealing with this wastewater are now an issue. Currently, North Dakota locks it into deep injection wells in the Bakken formation. With the development of membrane technologies to treat wastewater, it may be feasible to treat the wastewater and reuse it. This study uses a mathematical programming model to minimize the total cost of dealing with wastewater using three methods - deep well injection, on-site treatment, and off-site treatment. The model results show it is cost-effective to use on-site and large capacity off-site treatment to treat the 20% of the wastewater that flows back within the first 30-60 days after a well is drilled.
433

No-migration variances - 40 CFR section 268.6general procedures and requirements for submitting a petition to continue the land disposal of restricted wastes

Finkel, Howard S. 02 February 2010 (has links)
<p>A review of the petitioning process and informational requirements was compiled to assist owners/operators of Resource Conservation and Recovery Act (RCRA) facilities in obtaining a variance from the Land Disposal Restrictions Program.</p> <p> A discussion of the RCRA legislative intent of the Land Disposal Restrictions Program as it applies to no-migration variances and the types of facilities the Environmental Protection Agency (EPA) considered likely candidates are provided.</p> <p> A checklist of the required information for a technically complete petition also is included.</p> / Master of Science
434

A multi-attribute analysis of nuclear waste disposal alternatives

Taiyabi, Asif A. 02 February 2010 (has links)
Master of Science
435

Model Study and Analysis of the Flow Elements of a Recirculation Mixing System

Berg, Albert Warren 11 July 1967 (has links)
The term water clarifier as used in this text refers to a versatile water treatment unit which combines flocculation and coagulation, clarification and positive sludge removal in a single tank. Water clarifiers are very compact units which are being used in municipal and industrial water treatment for the removal of turbidity, algae, color, iron and silica; lime or lime-soda softening; magnesium precipitation; brine clarification; and waste water clarification with or without chemicals. Water clarifier units have found wide use in the sanitary field, providing high removals in the pre-treatment of sewage and in secondary sewage treatment through addition of coagulants.
436

Hazardous air pollutants from the waste incineration industry : formation mechanisms, distribution characteristics, and potential environmental risks

Wang, Chen 07 September 2020 (has links)
In this study, the formation mechanisms, distribution characteristics, and potential environmental risks of hazardous air pollutants from industrial-scale waste incineration processes were investigated. First, to clarify the dominant formation mechanism of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) in a hazardous waste (HW) incinerator, three tests were designed by adding different precursors in phenol-containing raw materials. With the addition of p-dichlorobenzene, PCDD/F levels at the quenching tower outlet were ten times higher than levels observed at the inlet. This indicates that the quenching tower failed to suppress the formation of PCDD/Fs and surface-mediated precursor reaction is the dominant formation mechanism in low-temperature stages. Besides, adsoprtive memory effect in air pollution control devices (APCDs) also led to high PCDD/F emissions. These findings suggest that to control PCDD/F emissions, strict regulation of chlorine contents in feed materials and frequent cleaning of APCDs are necessary. Meanwhile, single particles and solid residues were collected from the same HW incinerator. Morphologies and elemental compositions of particles in flue gas and indoor air were characterized by transmission electron microscopy-energy dispersive X-ray spectrometry (TEM-EDS). Eight types of single particles were classified, as organic, soot, K-rich, S-rich, Na-rich, Fe-rich, mineral and fly ash particles. The heavy metal partitioning behavior study suggested that Hg, Cd and Pb were mainly enriched in fly ash through evaporation, condensation, and adsorption; while Cr, Cu, Mn, and Ni were mostly remained in the bottom ash due to their low volatilities. In addition, the study also investigated environmental behaviors of certain characteristic pollutants. Thrity-two soil samples surrounding a cement plant co- processing HW were collected and analyzed for the presence of 16 polycyclic aromatic hydrocarbons (PAHs) and 12 heavy metals. Ten samples were selected for PCDD/Fs analysis. The highest concentration of PCDD/Fs occurred 1200 meters downwind from the cement plant. Levels of ∑16 PAHs ranged from 130.6 to 1134.3 μg/kg in soil. Source identification analysis suggested that the cement plant was the most likely source of PAH contamination. The concentrations of Cd and Hg were on average two times and six times higher than background values, respectively. Both incremental lifetime cancer risk model (ILCR) for PAHs and potential ecological risk index (RI) for heavy metals indicate potential risks to the population and the environment surrounding the cement plant. Last, to identify whether waste incineration is a major source for airborne environmentally persistent free radicals (EPFRs), tree leaf samples were collected from 120 sites surrounding four waste incinerators and one urban area. EPFR concentrations on leaves ranged from 7.5 × 10 16 to 4.5 × 10 19 spins/g. For the 10 N.D. samples, they were all collected from areas inaccessible by vehicles. Although previous work has linked atmospheric EPFRs to waste incineration, the evidence in this study suggests that vehicle emissions, especially from heavy-duty vehicles, are the main sources. According to our estimation, over 90% of the EPFRs deposited on tree leaves might be attributed to automotive exhaust emissions, as a synergistic effect of primary exhausts and degradation of aromatic compounds in road dust
437

South African urban solid waste legislation and its application : proposals towards reform

Botha, Llewellyn January 1988 (has links)
Bibliography: pages 101-109. / The over-production by Man of waste and the consequent threat to life on Earth motivated this study of urban solid waste legislation and its application in South Africa. "Urban solid waste" was seen as solid waste generated within an urban area by secondary industrial and commercial processes, domestic activities and littering, and deposited on land. The unique South African context, in which the relevant legislation has developed and been applied, was acknowledged. The overall objective was both: a) to ascertain the extent to which the relevant legislation and fulfils its functions in terms of its raison d'etre, and achieves its objectives; b) to formulate guiding principles for reform of the legislation. In order to achieve the overall objective, the following five specific objectives were undertaken: 1; To ascertain which existing and contemplated South African legislation relates to urban solid waste. 2. To establish: * the raison d'etre of legislation, * accepted criteria for good legislation. 3. To evaluate the relevant legislation, using the aforesaid criteria. 4. To ascertain, from waste managers: * problems experienced or foreseen by them whilst operating within the relevant legislation, and * their proposed solutions to those problems. 5. To formulate guiding principles for reform of the legislation.
438

Some effects of the copper ion on the activated sludge stabilization process /

Directo, Leon Selloria January 1961 (has links)
No description available.
439

A study of turbulent heat transfer on rough surfaces in a square duct with asymmetrical heating applicable to nuclear waste repository configurations /

Hsieh, Shou-Shing January 1983 (has links)
No description available.
440

Sewer System Evaluation Surveys Conducted in Industrial Plants

Cadle, Robert B. 01 July 1980 (has links) (PDF)
"Sewer System Evaluation Surveys Conducted in Industrial Sewers," describes the methods employed and the results of Sewer System Evaluation Survey studies conducted at two industrial complexes. The procedural techniques for locating and quantifying infiltration and inflow into sewer systems represented to provide a basic understanding of the steps required to complete such studies. Case studies of actual surveys conducted at two privately operated industrial plants in Tennessee are presented to illustrate the utilization of the investigative techniques. The results of the studies are compared with each other and with similar studies conducted in municipal sewer systems.

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