• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 285
  • 40
  • 12
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 2
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 390
  • 390
  • 154
  • 100
  • 63
  • 54
  • 50
  • 46
  • 45
  • 42
  • 40
  • 38
  • 36
  • 36
  • 34
  • 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.
251

Enskilda avlopp : Ett kommunalt ansvar? / Individual sewage disposal system : A municipal responsibility?

Eriksson, Gustav January 2013 (has links)
Vattnet är en livsviktig resurs för levande organismer och ekosystem. Idag används vatten i alla möjliga sammanhang vilket har lett tillatt vattnet har blivit övergött och förorenat. Utsläpp av näringsämnen i för stora mängder anses vara den största orsaken til lövergödning och detta gäller framför allt utsläpp av avloppsvatten. Syftet med denna uppsats var att undersöka Sveriges kommunerskartläggningsstrategier för enskilda avlopp och vilka åtgärder de vidtar, samt hur många enskilda avlopp det finns. För att ta reda pådetta skickades en enkät och ett följebrev ut till alla kommuner i Sverige och sedan sammanställdes dessa. Av Sveriges 290 kommunervar det 232 som deltog. De vanligaste strategierna för att kartlägga enskilda avlopp är att skicka ut enkäter eller göra inventeringar. I många fall används bådastrategierna med enkät som ett första steg och inventering som ett andra. Resultatet av enkäten visar att mellan 50-90 % av de enskildaavloppen är undermåliga eller bristfälliga och att åtgärder krävs. Kommunerna ställer krav på fastighetsägarna att åtgärda sina avloppinom en viss tidsram annars kan förbud att använda avloppen utfärdas. Undersökningen visade att det finns ungefär 813 000 enskilda avloppsanläggningar i Sverige, vilket är en ökning med cirka 71 000 sedan2006. Ökningen kan bero på att fler än hälften av Sveriges kommuner har gjort en kartläggning sedan 2006
252

Gefährliche Stoffe in Kläranlagen

Schneider, Petra, Günther, Thomas, Gottschalk, Nicole, Zänder, Daniel 22 April 2010 (has links) (PDF)
Gefährliche Stoffe gelangen durch Abwässer aus Haushalten, Industrie und Landwirtschaft in Kläranlagen. Während der mechanisch-biologischen Abwasserbehandlung in konventionellen Kläranlagen werden nur wenige Stoffe mit toxischen, persistenten und bioakkumulierenden Eigenschaften eliminiert. Der Bericht beschreibt die Eigenschaften gefährlicher Stoffe - darunter Industriechemikalien, Pflanzenschutzmittel, Arzneistoffe, Hormone und Metalle, ermittelt Quellen des Stoffeintrages und leitet Möglichkeiten zur Verringerung der Stoffeinträge ab. In Laborkläranlagen wurde eine Methodik entwickelt, mit der bei Anlagen mit biologischer Grundreinigung und weitergehender Reinigung (Stickstoffeliminierung) die Eliminierungsrate für ausgewählte gefährliche Stoffe ermittelt werden kann. Die Eliminationsraten der untersuchten gefährlichen Stoffe sind sehr unterschiedlich. Während ausgewählte Pestizide nur in geringem Umfang eliminiert werden (Bentazon < 40 Prozent, Dichlorprop < 30 Prozent, Dibutylzinn < 50 Prozent), werden für Nonylphenolethoxylate, Phthalate und Trichlormethan hohe Eliminationsraten mit bis zu 99 Prozent ermittelt.
253

Environmental risks, subjectivity, and political choices : the Korean case /

You, Seungkwon, January 2002 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 231-239). Also available on the Internet.
254

Environmental risks, subjectivity, and political choices the Korean case /

You, Seungkwon, January 2002 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 231-239). Also available on the Internet.
255

Odour control and management in Hong Kong sewage treatment infrastructures

Wong, Ying-kin, 黃英健 January 2013 (has links)
Many complaints were received from the residential area around the Shatin Sewage Treatment Works (STSTW) about the presence of odour. The dominant odour marker H2S was selected to be studied. A review of the odour measurement and sampling methods, together with the specification of the standard limits and health effects were made. The formation process of H2S was investigated and the abatement and control measures in terms of physical, chemical and biological techniques were compared. The monthly rate of H2S emission in the atmosphere was calculated from the soluble sulfide and the measured wastewater flow at the inlet works, primary sedimentation tanks, aeration tanks, and sludge digestive and storage tanks, and the H2S mapping was carried out at the same places. Meteorological data including wind speed, wind direction, temperature and pressure were collected. The effect of temperature and pH on H2S generation is shown, and the effectiveness of odour control and deodourization processes was studied. A Gaussian dispersion model of Industrial Source Complex version 3 (ISC3) was applied in predicting the ground H2S level at various air sensitive receivers in the vicinity of STSTW. None of the places exceeded the recommended H2S concentration of World Health Organization (WHO) and the odour is a localized problem in STSTW of 35% area having H2S ranging in 0.01--‐0.023ppm. Recommendations are suggested in both short-term improvement in operation and maintenance practice and long-term design and construction of sewage treatment facilities. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management
256

Hydrogeochemistry of stream channel recharge of sewage effluent, northwest of Tucson, Arizona

Esposito, David M. January 1993 (has links)
This investigation has documented the water quality impacts of stream channel recharge of sewage effluent northwest of Tucson and has evaluated the hydrogeochemical mechanisms potentially responsible for observed water quality changes. The evaluation was accomplished partly through construction of twelve monitor wells and implementation of a quarterly water quality monitoring program for surface water and groundwater. Constituents monitored included major inorganic chemical constituents, trace inorganics, trace metals, priority pollutants/trace organics and microbiological contaminants. ¹⁵N also proved useful in the study. The significance of a reducing zone immediately beneath the bed of the Santa Cruz River with respect to denitrification was documented. Findings of this investigation indicate that while sewage effluent is of poor quality with respect to drinking water standards, groundwater recharged by sewage effluent is of improved quality. Other findings include: * Nitrate in shallow groundwater near the Santa Cruz River in the Cortaro area appears to be primarily from stream channel recharge of sewage effluent; * Nitrate-N contents of effluent recharged groundwater averaged about 5 mg/1, well below the maximum contaminant level for drinking water of 10 mg/1, representing a 75 percent loss in total nitrogen during stream channel recharge of sewage effluent (assuming no mixing); * Both stream channel recharge of sewage effluent and agricultural deep percolation contribute to nitrate in shallow groundwater near the Santa Cruz River in the Marana area; * The reducing zone beneath the Santa Cruz River may be responsible for denitrification losses of up to 5 mg/1 of nitrate-N. This would explain approximately 30 percent of nitrogen losses, on average, between effluent and recharged groundwater; * The mechanisms of cation exchange and mixing with groundwater from other sources can explain the major changes in water quality between effluent and groundwater with respect to major inorganic chemical constituents; * Renovation of effluent with respect to coliform bacteria and enteric viruses content during recharge is not complete.
257

Decentralizing the Strategic Sewage Disposal Scheme of Hong Kong: the reasons and the potential modifications

Li, Mo-yee, Deanna., 李慕儀. January 2000 (has links)
published_or_final_version / abstract / toc / Applied Geosciences / Master / Master of Science
258

Resistance of indicator organisms to chlorination

Clinger, Robert Christopher, 1946- January 1970 (has links)
No description available.
259

Development of a code of practice for co-disposal to obviate inimical environmental impacts of generated gases and leachates.

Daneel, Richard A. January 1996 (has links)
Despite its phasing out in numerous countries, such as Germany and the U.S.A., co-disposal of hazardous waste with municipal solid waste continues to be widely practised in South Africa. Co-disposal utilises properties and microbial activities in the refuse to attenuate the hazardous waste and thus obviate its environmental impact potential. All landfill operations require careful planning in not only site selection criteria but also the type and amount of various wastes accepted for disposal. It is clear, however, that the practice of co-disposal requires special precautions and management as the methods employed in the landfill operation determine to a large extent the environmental effects and, thus, the public acceptability of the operations. Although co-disposal is not suitable for all industrial wastes the results of recent research efforts, conducted mainly in the U.K., have indicated that, when properly managed, co-disposal can be regarded as a safe and efficient disposal option for many hazardous wastes. Environmental awareness in many European countries ensures that numerous hazardous compounds are either recycled or recovered. Unfortunately, in South Africa the lack of similar concern has resulted in increased concentrations of toxic compounds being co-disposed on a regular basis. Since fundamental studies of this technology, pertaining to South African conditions, have been lacking laboratory models/microcosms were built to address this paucity. Model. To effect the separation of species habitat domains of component species of growth rate-dependent interacting microbial associations responsible for terminal catabolic processes of the refuse fermentation, with retention of overlapping activity domains, and so facilitate examination of species in isolation without violating the integrity of each association, multi-stage models were constructed. The accidental overgassing of the culture with liquid petroleum gas (LPG) effected interesting fermentation balance changes which also emphasised the need for an Anaerobic Bioassay Test to assess the impacts of specific perturbants. Evidence of differential susceptibility of the component species to phenol was demonstrated in this study. Microcosm. A total of 42 refuse packed single-stage glass column bioreactors were commissioned and subjected to phenol and/or anaerobically digested sewage sludge codisposal. The effects of four different operational modes: leachate discard (single elution); leachate recycle; batch; and simulated rain on the co-disposals as well as refuse catabolism per se were examined. The results of these studies indicated that protracted periods of adaption to phenol (1000 and 2000 mg l -1) could have resulted from nutrient (elemental) limitation. Circumstantial evidence was also gained which indicated that the nitrate- and sulphate-reducing bacteria (SRB) were particularly sensitive to the added xenobiotic. Further, without the effective participation of the nitrate- and SRB the active and total fermentation of both the phenol and refuse components were depressed. It was also determined that the operating regime employed was a key factor in refuse degradation although with time, and especially following the phenol resupplementations, the operating conditions played a less significant role. In general, the single elution operated columns demonstrated increased phenol removal rates which were, unfortunately, coincident with low pH values and increased leachate residual phenol concentrations. Leachate recycle, on the other hand, unlike the batch operated columns, facilitated increased pH values and methane evolutions. The simulated rain columns were characterised by rapid washout of the added phenol as well as methanogenic precursors. The sewage sludge co-disposal experiments, likewise, demonstrated that, depending on the sludge:refuse ratio, the operating regime was extremely important in optimising the refuse degradation processes although, in general, leachate recycle appeared to be the most favoured method of operation. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1996.
260

Microbiological investigations into granular sludge from two anaerobic digesters differing in design and industrial effluent purified.

Howgrave-Graham, Alan R. January 1995 (has links)
Due to a combination of selection criteria, sludges from upflow anaerobic digesters treating industrial waste waters consist primarily of well-settling, dense agglomerates called granules. Quantification of the component mixed microbial populations of these granules has been severely restricted by the inability of researchers to disrupt them without concomitantly destroying numerous cells. In situ quantification using light and electron microscopy is complicated by the high cell numbers and bacterial diversity; the small cell size; and the destructive nature of electron microscopy preparative techniques preventing the viewing of more than a small percentage of the population at a time. For these reasons, in this investigation, standardization of qualitative electron microscopic techniques was performed prior to their application to granules. Isolation and electron and light microscopic techniques were applied to granules from a fullscale clarigester treating effluent from a maize-processing factory. In addition, a method using montaged transmission electron micrographs (TEMs) taken along a granule radius, and image analysis, was developed for bacterial quantification within granules. This method, together with antibody probe quantification, was applied to granules from an upflow anaerobic sludge blanket (UASB) digester treating a brewery effluent. The clarigester granules contained a metabolically and morphologically diverse population of which many members were not isolated or identified. By contrast, the UASB digester granules consisted primarily of morphotypes resembling Methanothrix, Methanobacterium and Desulfobulbus, in order of predominance. However, only about one-third of the population reacted with antibody probes specific to strains of bacterial species expected to occur within these granules. According to the antibody probe library used, the Methanobacterium-like cells observed in TEMs were probably Methanobrevibacter arboriphilus. From this study it is apparent that different anaerobic digester designs, operational parameters, and the chemical composition of the waste water purified, are factors which influence the formation and maintenance of granules differing with respect to their microbial populations. Until the difficulties associated with quantification are overcome, the processes governing granule formation and/or population selection will remain obscure. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1995.

Page generated in 0.0417 seconds