• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1536
  • 776
  • 181
  • 48
  • 26
  • 23
  • 20
  • 18
  • 17
  • 17
  • 17
  • 17
  • 17
  • 17
  • 14
  • Tagged with
  • 3435
  • 3435
  • 770
  • 734
  • 706
  • 651
  • 415
  • 386
  • 279
  • 260
  • 253
  • 231
  • 218
  • 211
  • 207
  • 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.
741

Development of a classification system for the recreational environmental quality of beaches

Wild, Elizabeth Anne January 2001 (has links)
No description available.
742

The use of chemical analyses, bioassays and benthic biomonitoring in the toxicity assessment of complex industrial effluents /

Sarakinos, Helen C. January 1997 (has links)
This research examined the toxicity of complex industrial effluents as measured by chemical analyses, whole effluent toxicity (WET) tests and surveys of the receiving water biota. Toxicity of final effluents from 45 diverse facilities was examined to determine whether inferred toxicity based on presence and concentration of priority substances could predict WET, calculated from a battery of bioassays on bacteria, cladocerans and algae. Following corrections of inferred toxicity for particle-bound contaminants and adjustment for free ion activity, correlation between inferred and whole effluent toxicity was highly significant. Effluents with elevated metal concentrations exhibited lower WET than predicted, likely due to negative interactions among trace metals; kraft mill effluents exhibited higher WET than predicted which is consistent with findings in the literature. / The ability of laboratory WET tests to predict thresholds of invertebrate community response to a complex industrial effluent was examined. Patterns in invertebrate community structure were detrended for environmental factors and compared to measured instream effluent concentrations. Laboratory effect thresholds, reported as Maximum Allowable Toxicant Concentrations (MATC), were calculated from a battery of toxicity tests on bacteria, algae, cladocerans and fish. Declines in taxonomic richness corresponded to calculated lab thresholds, while changes in abundance of total taxa and sensitive taxa, (Ephemeroptera, Plecoptera, Trichoptera) occurred at lower concentrations than predicted from MATCs. The tendency for invertebrate abundance to decline at lower instream effluent concentrations than richness supports findings in the literature. Lack of correspondence between lab and field thresholds may be ameliorated by the addition of behavior endpoints, (e.g. avoidance) to toxicity tests.
743

Economic Policy and Resource Implications of Biofuel Feedstock Production

Adusumilli, Naveen 2012 August 1900 (has links)
Dramatically higher fuel prices and massive petroleum imports from politically unstable countries have contributed to a major national initiative to generate renewable fuels in the United States. Often, such policies are enacted and implemented with huge taxpayer expenditures without due diligence to the consequences. The evaluation of the water quality impacts of converting pastureland to intensive biomass production for fuel in a southern Texas watershed suggest significant increases erosion and nutrient loadings to water bodies. The Best Management Practices (BMPs), cover crop and filter strips when implemented individually failed to produce status-quo reduction levels. Combined BMPs implementation produced improved mitigation, at substantially higher costs, highlighting the issue of sustainability related to the economics of renewable fuels. The estimation of the net energy of biomass ethanol accounting for the production input data indicate a greater than one energy return for biomass crops. However, the policy results indicate that only 70 percent in net contribution to the energy supply is achieved due to relatively lower energy returns compared to conventional fossil fuels. In addition, because the ethanol produced has to have the energy used deleted from the total, the cost of producing a gallon of biomass ethanol is substantially higher than that of gasoline. The impacts of an exogenously-specified biofuel mandate fulfilled by the production of a dedicated biomass crop and its consequent effects on commodity prices and overall welfare are estimated. Net farm income increased due to an increase in crop prices; however, both consumer surplus and total surplus decreased. The analysis is extended to estimate the sensitivity of Conservation Reserve Program (CRP) acres returning to crop production and the potential of higher biomass yields. The results indicate that net farm income decreased and consumer surplus increased due to a decrease in crop prices, resulting in an increase in overall welfare. This current research evaluates the unintended consequences of the U.S. energy policy and provides interesting insights of the potential economic and environmental impacts. These results suggest policy makers should be cautious before enacting energy policy and consider multiple alternative energy sources in an economic and financial context to achieve a sustainable energy goal.
744

Comparing the distribution of pathogenic bacteria and common indicator microorganisms in biofilms on different surface types in an agricultural watershed in British Columbia (Canada)

Maal-Bared, Rasha 11 1900 (has links)
Little is known about the distribution of bacterial indicators and pathogens in biofilms on different surface types in natural aquatic environments. This study was conducted to examine the distribution of pathogens and indicator bacteria in biofilms in an agricultural watershed. The study particularly focused on whether biofilms can act as sinks for pathogenic organisms and could be monitored to protect public health. To do so, we monitored the presence of faecal contamination indicators (heterotrophic plate counts, faecal coliforms, enterococci, and E. coli) and particular pathogens (E. coli 0157, Campylobacter sp. and Salmonella sp.) in water, sediment, and in biofilms on river and slate rock, wood, sandpaper, and Lexan™ in Elk Creek (British Columbia, Canada) from December 2005 to April 2007. Faecal indicator concentrations and pathogen presence were evaluated using standard culturing and isolation methods. The results showed that both faecal indicators and pathogens were present at the headwaters and that the use of water column grab samples underestimated faecal indicator numbers. Also, water column grab samples during the dry season were not representative of pathogens present in the creek. This indicates that biofilms might be the main reservoir of Salmonella sp. and pathogenic E. coli O157 in the summer when rainfall (which results in flow changes and sloughing) is limited. Campylobacter sp. was not retrieved in the dry season. Campylobacter on sediment, slate rock and wood showed high correlations with nitrates and enterococci, which could be used as faecal contamination surrogates. Numbers of indicator organisms and pathogens in one-month biofilms were compared to those in long-term biofilms (colonized 12 and 24 weeks) and short-term biofilms (colonized one to three weeks). The comparison showed that surface type, colonization period and water quality all affected the concentration of indicator organisms and pathogens present in biofilms. Finally, results showed high levels of phenotypic antibiotic resistance of E. coli and pathogenic E. coli O157 isolated from the watershed (even at the headwaters), particularly to tetracycline, ampicillin and streptomycin. This study highlights the potential biofilms could play in prediction of water quality changes, the improvement of sampling methods, and the study of aquatic environments.
745

Assesment of drinking water quality using disinfection by-products in a distribution system following a treatment technology upgrade

Bush, Kelly Lynn 05 1900 (has links)
Chlorine is the most widely used disinfectant for drinking water treatment. Chlorine canreact with natural organic matter (NOM) in water sources resulting in the formation of potentially carcinogenic disinfection by-products (DBPs). The most common DBPs measured in chlorinated drinking water distribution systems are trihalomethanes (THMs) and haloacetic acids (HAAs). In 2005, the City of Kamloops, British Columbia upgraded the drinking water treatment system to ultrafiltration membrane treatment. The objective of this study was to determine the extent to which upgrades to a drinking water treatment system, specifically, implementation of an ultrafiltration treatment process, impacted DBP formation within a distribution system. This study used a two-phase research approach. Phase I of the study was a distribution system monitoring program that collected water samples and physical and chemical information using data loggers at five sampling sites within the distribution system. Phase II of the study used bench-scale simulations that modeled DBP formation using a flow-through reactor system, the material-specific simulated distribution system (MS-SDS), constructed of pipe material resurrected from the City of Kamloops distribution system. Phase I results suggested that implementation of the ultrafiltration treatment process and accompanying treatment system upgrade was not effective at reducing the concentration of DBPs delivered to consumers. Concentrations of THMs remained relatively constant at sampling sites, while concentrations of HAAs increased following implementation of the ultrafiltration treatment process. The increase in HAA formation was likely due to an increase in retention time of the water within the distribution system following implementation of the ultrafiltration treatment process, rather than due to the treatment process itself. The results of this study are consistent with previous work on South Thompson River water DBP precursors, which suggested that THM and HAA precursors of this source water are small and hydrophilic, and therefore cannot be removed by ultrafiltration processes. Phase II results showed that the MS-SDS was more representative of distribution system c onditions than traditional glass bottles to estimate DBP formation. It is recommended that the MS-SDS be used in parallel with a simultaneous distribution system monitoring program to estimate distribution system retention times from THM and HAA concentrations.
746

Management and reuse of local water resources in residential developments in Adelaide /

Barton, Annette Unknown Date (has links)
This thesis reports on research undertaken into the integration of water reuse systems into medium to high density residential developments in the semi-arid climate environment of metropolitan Adelaide. The research has focused on maximising the reuse of local water resources for residential lifestyle purposes, through the incorporation of relatively simple water sensitive systems into subdivision type developments, where allotments are less than 500 sq.m. / The quantities and qualities of the local water resources- roof runoff, surface runoff and wastewater- are considered and a paradigm for their reuse presented in which each local water resource is linked with a residential use sector- in-house, ex-house and public space- in order to minimise treatment requirements. On the basis of this paradigm a water sensitive residential model (WSRM) is developed. This model constitutes a subdivision layout which incorporates reuse systems while endeavouring to keep water systems infrastructure to a minimum. / Following on from this, the feasibility of the WSRM has been investigated by applying it to three conventional residential developments within metropolitan Adelaide. These are located in the suburbs of Mawson Lakes, Taperoo and Aldinga Beach. The specific physical, topographic and hydrogeological conditions associated with each site have required a flexible approach to the application of the model; and while a unique arrangement has been found for each site, the basic elements of the WSRM have provided an underlying consistent theme across them all. / Water balance modelling using the WaterCress program has been undertaken for each site to gain an understanding of the level of 'water-self-sufficiency' that might be achieved with the WSRM. Modelling results have indicated that between 50-70% of domestic water needs can be satisfied using local water resources. / An economic assessment has been undertaken of the WSRM from the point of view of development costs. The water reuse systems have been designed and costed for each site. Development fees and charges have also been ascertained. This has enabled a comparison to be made with the costs and development charges of conventional type developments. It is concluded that while the costs of the WSRM developments were consistently greater than for conventional developments, the increasing need for developers to contribute to external works relating to infrastructure and the environment is altering the balance. When account is given to these external costs, 'reuse' developments are at least as equally viable as conventional developments. / The research has produced a practical model to build reuse systems into the fabric of the residential development, significantly reducing reliance on the mains water supply and creating more sustainable developments. It has also shown that the economics of such developments are changing for the better. / Adelaide, like other Australian capital cities, is presently beset with complex issues relating to water supply, wastewater and stormwater management. Better management and more sustainable use of the available water resources is needed; maximisation of water reuse and more efficient use of local water resources are becoming increasingly important. / The trend in Australia today is for medium to high density housing for inner city infill or redevelopment sites and for outer suburb greenfield sites. Water sensitive residential developments within Australia, which have incorporated water reuse, have generally been located in high rainfall areas (average rainfall above 1200mm/year) and/or where the average allotment size is greater than 600 sq.m.. Two exceptions to this are the New Haven village and Mawson Lakes developments in the greater Adelaide region, where the average rainfall is around 500mm/year. In these two cases, however, reuse accounts mainly for ex-house water uses; in-house water uses are essentially serviced by the mains supply with toilets being the only exception. / Thesis (PhD)--University of South Australia, 2005.
747

An exploratory study of industrial customers' perceptions of service quality of a privatized water company in Malaysia /

Ching, Lee Yow Unknown Date (has links)
Malaysia embarked on a privatization program in 1983. The overall aim was to relieve the financial and administrative burden of the government and to improve the efficiency and productivity of government enterprises. One of the sectors privatized was the water supply in Penang with the major objective of ensuring that the privatized water company, known as Penang Water Supply Corporation (PWSC), provides better quality services to its customers. The PWSC must attempt to satisfy its customers who must perceive that their needs are being met and to capture the voices of the customers in order to provide improved services. / This study assessed the suitability of the SERVQUAL instrument for measuring service quality in Malaysian water supply sector. It attemped to evaluate the quality of services provided by PWSC through the use of the SERVQUAL instrument to measure industrial customers' expectations and perceptions of the quality of service. SERVQUAL measures five service dimensions: tangibles, reliability, responsiveness, assurance and empathy. Expectations, perceptions and service quality scores were assessed and their significance interpreted. The research was conducted via a questionnaire survey. The results indicated that SERVQUAL to be an appropriate instrument to measure water supply service in Malaysia and three factors appear as dimensions of service quality. Analysis of the results revealed that industrial customers rated the service quality provided by PWSC as above average. Higher expectation than perception scores were recorded on all features of service quality indicating that customers expected a better quality of service from PWSC. An Extended Gaps Model of Service Quality was used to identify the factors contributing the service quality shortfalls. Strategies to improve service quality of PWSC were proposed. / Thesis (DBA(DoctorateofBusinessAdministration))--University of South Australia, 2004.
748

Method development for the determination of epichlorohydrin in drinking water /

Clivet, Isabelle Marie Beatrice. Unknown Date (has links)
The aim of this project was to develop a method for the determination of epichlorohydrin in drinking water. First, epichlorohydrin was studied on gas chromatography (GC) to determine the retention time. Then, epichlorohydrin was used to optimise the GC parameters : best detector, detector temperature, total detector flow, injector temperature and column temperature program. Secondly, epichlorohydrin was extracted by Solid Phase Micro-Extraction (SPME) and by Solid Phase Extraction (SPE) and analysed by GC to optimise the extraction mode parameters : SPME extraction mode, salt saturation, fibre selection, sample temperature, fibre placement, stirring and vibration, extraction time ; SPE tube selection, volume of extraction, extraction flow rate, salt saturation, drying process, solvent of elution, volume of solvent. Thirdly, the limit of detection of both extraction modes by GC was looked at to decide on the best extraction technique for epichlorohydrin. Fourth, epichlorohydrin was extracted by SPME direct immersion and analysed by gas chromatography/mass spectroscopy (GC/MS). A calibration curve was obtained with the analyses of Milli-Q water sample spiked with epichlorodydrin. A limit of detection was determined at 0.38 μg/L. Finally, water samples from the Adelaide distribution system were analysed by GC/MS through two columns but epichlorohydrin could not be separated from bromodichloromethane present in drinking water from the disinfection process. / Thesis (MEng(HydrologyWaterResources))--University of South Australia, 2003.
749

Best practices in drinking water quality regulation :

Moeller, Anthony. Unknown Date (has links)
Thesis (PhD)--University of South Australia, 2001.
750

Laboratory and field evaluation of a lead smelter effluent in the upper Spencer Gulf, South Australia /

Ross, Kirstin. Unknown Date (has links)
Thesis (PhD)--University of South Australia, 2001.

Page generated in 0.0607 seconds