• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 927
  • 701
  • 118
  • 107
  • 95
  • 73
  • 25
  • 16
  • 16
  • 14
  • 12
  • 9
  • 9
  • 7
  • 6
  • Tagged with
  • 2505
  • 1207
  • 523
  • 413
  • 360
  • 342
  • 240
  • 227
  • 201
  • 199
  • 186
  • 167
  • 164
  • 161
  • 155
  • 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.

Spatiotemporal Patterns of Petroleum Hydrocarbons and Wastewater Compounds, and their Effects on Growth and Gene Expression in the Blue Crab, Callinectes sapidus

January 2017 (has links)
acase@tulane.edu / Environmental pollution has been steadily increasing after the industrial revolution and the consequential increased human activity. A contemporary trend of concern is chemical pollution, and one class of chemical pollutants are endocrine disrupting chemicals (EDCs). These compounds have the ability to impair endocrine function in organisms, and can therefore induce molecular or physiological sub-lethal effects. EDCs enter marine environments either with wastewater or off shore industrial activities, such as oil drilling. Marine organisms can be exposed either chronically through presence of low concentrations of EDCs in the environment, or through accidental spills, such as the Deepwater Horizon (DWH) oil spill in the northern Gulf of Mexico (NGOM) in 2010. The blue crab, Callinectes sapidus, is an economically and ecologically important invertebrate in the NGOM. Because the blue crab has both pelagic and benthic life history stages, it is possible that the blue crab can encounter pollutants from both near shore and off shore sources. Also, this biphasic life history makes the blue crab an important link between pelagic and benthic ecosystems. In this dissertation I investigated what contaminants are present in post-larval blue crabs on a wide spatial scale, and if evidence of contamination from the DWH oil spill can be detected. I also exposed juvenile blue crabs to oil, dispersed oil, and two wastewater compounds and measured effects on growth and gene expression. This research provides important information about contemporary contaminants in the NGOM and how environmentally relevant concentrations of contamination affects blue crabs on a sub-lethal level. / 1 / Susan C Chiasson

Integration of wastewater treatment in agro-ecosystems /

Geber, Ulrika, January 1900 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Bioaugmentation of oil and fat degradation in the laboratory

Brooksbank, Adele Mary January 2003 (has links)
No description available.

Biotreatment of industrial effluents containing naphthalene sulphonate

Senior, Kerry Charles January 2003 (has links)
No description available.

Abundance of pathogenic bacteria and viral indicators in chlorinated effluents produced by four wastewater treatment plants in the Gauteng Province, South Africa

Dungeni, M, van der Merwe, RR, Momba, MNB 05 October 2010 (has links)
Abstract The failure of South African wastewater treatment plants to produce effluents of a high microbiological quality is a matter of great concern in terms of the pollution of water resources. This study aimed at assessing the effectiveness of 4 wastewater treatment plants in the Gauteng Province, namely the Zeekoegat, Baviaanspoort, Rayton and Refilwe Water Care Works (WCW), in the removal of pathogenic bacteria and viral indicators. Also taken into consideration were free chlorine concentrations and turbidity levels, which were measured using standard methods. Conventional methods and/or polymerase chain reaction (PCR) techniques were used to detect and identify pathogenic bacteria and coliphages. The turbidity ranged from 2.39 to 62.40 NTU and the concentrations of free chlorine ranged from 0.03 to1.60 mg∙ℓ-1 for all plants. Despite high free chlorine residual concentrations in treated effluents, the survival and occurrence of Escherichia coli, Salmonella typhimurium and Vibrio cholerae were significantly higher at Baviaanspoort (100%, 88.2% and 35.3%), Refilwe (87.5%, 59.4% and 21.9%) and Rayton (75%, 38.2% and 9.4%) compared to Zeekoegat, which only showed the survival of E. coli, at a much lower occurrence rate of 8.8%. Somatic and F-RNA coliphages were removed at 15.57 % and 13.96% for Baviaanspoort, 11.62% and 22.42% for Refilwe, 25% and 32.10% for Rayton, and 40.41% and 52.57% for Zeekoegat WCW. Significant correlations were found between pathogenic bacteria and coliphages at all plants (r = 0.765 for Baviaanspoort, r = 0.904 for Zeekoegat, r = 0.680 for Refilwe, r = 0.796 or the Rayton WCW, p < 0.01). A combination of sedimentation, rapid sand filtration and chlorination processes was found to be a major prerequisite for the reduction of turbidity levels and viral indicators and the successful removal of pathogenic bacteria in the Zeekoegat WCW. This study therefore suggests an upgrading of the wastwater treatment plants by including processes such as rapid sand filtration and UV disinfection, which have proved to be effective in the removal and inactivation of pathogenic bacteria and viruses.

Enhancing Anaerobic Degradation of Lipids in Wastewater by Addition of Co-substrate

y.kuang@exchange.curtin.edu.au, Yunhua Kuang January 2002 (has links)
Anaerobic treatment systems are becoming increasingly popular to treat complex organic wastes that contain carbohydrates, proteins and lipids. Lipids are widely found in sewage and industrial wastewaters. Dairy, edible oil, fat refining, slaughterhouse, wool scouring, meat processing plants and grease-trap wastes from restaurants generate wastewater high in lipids. Although it is well known that lipids can be degraded by biological process, they have been reported to inhibit anaerobic processes by causing sludge flotation and wash-out. The inhibitory effect of lipids in anaerobic process has also been attributed to the long-chain fatty acids (LCFAs) which are the hydrolysed products of lipids. It has been shown that LCFA and lipids inhibit the formation of granular sludge in Upflow Anaerobic Sludge Blanket (UASB) reactors and that the adsorption of LCFAs on to the granules can result in its flotation and washout. It was also found that the degradation of LCFA was very poor. Various techniques have been employed to enhance degradation of lipids and these include physico-chemical pre-treatment, application of two stage treatment employing new reactor designs like Expanded Granular Sludge Bed (EGSB). This thesis investigated the influence of co-substrates, both in the form of hydrolysed products and polymeric form, on reducing the toxicity and enhancing the degradation of LCFA and lipids in a single stage and two stage upflow anaerobic sludge blanket (UASB) reactors. The investigations were carried out on both microbiological and physico-chemical aspects. A combination of techniques including the use of light microscopy (LM), confocal laser scanning microscopy (CLSM), transmission electron microscopy (SEM) and Fluorescent In Situ Hybridisation (FISH) was used to study the characteristics of microbial aggregates and to locate microbial populations within these aggregates. The microbial populations visualised using FISH techniques were Bacteria, Archaea, Methanobacteriaceae, Methanomicrobiales and Methanosarcinaceae. The performance of digesters was also monitored by measuring bulk parameters such as concentration of residual substrates, intermediate products (LCFAs, volatile fatty acids), methane (or gas) production rate and chemical oxygen demand of treated effluent. Initially batch assays were carried out to determine the effects of glucose (hydrolysis product of carbohydrate) and cysteine (hydrolysis product of protein) on the toxicity of sodium oleate (hydrolysis product of lipid) to methanogenesis. The results showed that glucose and cysteine addition could reduce the toxicity of sodium oleate on the methanogenesis and enhance the degradation of sodium oleate. While the addition of glucose had a better effect than cysteine on decreasing the toxicity of sodium oleate, the combination of glucose and cysteine had the optimal result to stimulate the degradation of sodium oleate. Secondly the effect of addition of glucose, cysteine and sodium oleate as co-substrates on the characteristics of granules in an LCFA fed single stage UASB were investigated. It was shown that the addition of glucose produced the best results on the formation of granules while both cysteine and sodium oleate adversely affected the granule formation. In a LCFA inhibited digester glucose and cysteine addition enhanced the recoveries of different anaerobic microbial communities. Although the effects of glucose and cysteine on the various microbial groups were different, the combination of glucose and cysteine had the optimal results on recoveries of all bacterial groups. The next half of the thesis investigated the influence of starch and yeast extract on the hydrolysis and degradation of canola oil by application of one and two stage UASB reactors. The results showed that the combined addition of protein and carbohydrate had an optimal effect on enhancing the hydrolysis of lipid compared to the addition of only protein or carbohydrate by promoting a balanced growth of the microbial groups. It was also demonstrated that a two- stage UASB reactor performed better in terms of extent of lipid hydrolysis and methanogenesis than a one-stage UASB reactor.

Peat as a metal trap for wastewater /

Ringqvist, Lena, January 1900 (has links) (PDF)
Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Low pH-induced polyphosphate accumulation by environmental microorganisms and its application in biological phosphate removal

Mullan, M. A. January 2003 (has links)
No description available.

Characteristics of a developing biofilm in a petrochemical wastewater treatment plant

Perera, Kuruppu Arachchige Kalyani, University of Western Sydney, College of Science, Technology and Environment, School of Science, Food and Horticulture January 2003 (has links)
A study was undertaken to investigate developing biofilms in a petrochemical wastewater treatment plant encompassing the architecture, microflora and the chemical nature of the matrix. Biofilms were developed on glass slides immersed in the activated sludge unit and analysed at known time intervals using a range of techniques. Initially, biofilms were investigated using conventional and emerging microscopic approaches to select a suitable technique. Scanning Confocal Laser Microscopy (SCLM) allowed visualisation of biofilms in situ with minimal background interference and non-destructive and optical sectioning which were amenable to quantitative computer-enhanced microscopy. SCLM was superior over Light microscopy and Scanning Electron Microscopy. This study demonstrated biofilm growth, presence of extracellular polymer substances (EPS) in early biofilms associated with cells and the development of porous nature of mature biofilms including channel-like structures. Overall new information has been obtained on developing biofilms in an Australian petrochemical wastewater treatment plant / Doctor of Philosophy (PhD) (Biological Sciences)

Development of an electrochemical primary treatment for hexahydro-1,3,5-trinitro-1,3,5-triazine laden wastewater

Johnson, Jared Lynn 08 August 2009 (has links)
This thesis explores the development of direct electrochemical reduction as a means of providing primary treatment of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in a manufacturing process waste stream. An industrial process wastewater laden with RDX was successfully treated in small batch reactors. Reaction kinetics were used to design a proof of concept bench scale flow reactor that utilized parallel packed electrode plates. Following successful testing of this reactor, a pilot scale packed electrode flow reactor was built. The reactor performance as a function of residence time was fit by a first order decay equation. Greater than 97% reduction of RDX in a process wastewater was observed at a reactor residence time of 27 minutes. The work presented herein was successful in creating an electrochemical treatment system capable of removing RDX from an industrial process waste stream with no chemical addition, and without creating an additional hazardous waste stream.

Page generated in 0.0771 seconds