953 resultados para 090508 Water Quality Engineering
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Abstract not available
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Mode of access: Internet.
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Dissertation elaborated for the partial fulfilment of the requirements of the Master Degree in Civil Engineering in the Speciality Area of Hydarulics
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A new dynamic model of water quality, Q(2), has recently been developed, capable of simulating large branched river systems. This paper describes the application of a generalized sensitivity analysis (GSA) to Q(2) for single reaches of the River Thames in southern England. Focusing on the simulation of dissolved oxygen (DO) (since this may be regarded as a proxy for the overall health of a river); the GSA is used to identify key parameters controlling model behavior and provide a probabilistic procedure for model calibration. It is shown that, in the River Thames at least, it is more important to obtain high quality forcing functions than to obtain improved parameter estimates once approximate values have been estimated. Furthermore, there is a need to ensure reasonable simulation of a range of water quality determinands, since a focus only on DO increases predictive uncertainty in the DO simulations. The Q(2) model has been applied here to the River Thames, but it has a broad utility for evaluating other systems in Europe and around the world.
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The catchment of the River Thames, the principal river system in southern England, provides the main water supply for London but is highly vulnerable to changes in climate, land use and population. The river is eutrophic with significant algal blooms with phosphorus assumed to be the primary chemical indicator of ecosystem health. In the Thames Basin, phosphorus is available from point sources such as wastewater treatment plants and from diffuse sources such as agriculture. In order to predict vulnerability to future change, the integrated catchments model for phosphorus (INCA-P) has been applied to the river basin and used to assess the cost-effectiveness of a range of mitigation and adaptation strategies. It is shown that scenarios of future climate and land-use change will exacerbate the water quality problems, but a range of mitigation measures can improve the situation. A cost-effectiveness study has been undertaken to compare the economic benefits of each mitigation measure and to assess the phosphorus reductions achieved. The most effective strategy is to reduce fertilizer use by 20% together with the treatment of effluent to a high standard. Such measures will reduce the instream phosphorus concentrations to close to the EU Water Framework Directive target for the Thames.
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Ensuring water is safe at source and point-of-use is important in areas of the world where drinking water is collected from communal supplies. This report describes a study in rural Mali to determine the appropriateness of assumptions common among development organizations that drinking water will remain safe at point-of-use if collected from a safe (improved) source. Water was collected from ten sources (borehole wells with hand pumps, and hand-dug wells) and forty-five households using water from each source type. Water quality was evaluated seasonally (quarterly) for levels of total coliform, E.coli, and turbidity. Microbial testing was done using the 3M Petrifilm™ method. Turbidity testing was done using a turbidity tube. Microbial testing results were analyzed using statistical tests including Kruskal-Wallis, Mann Whitney, and analysis of variance. Results show that water from hand pumps did not contain total coliform or E.coli and had turbidity under 5 NTUs, whereas water from dug wells had high levels of bacteria and turbidity. However water at point-of-use (household) from hand pumps showed microbial contamination - at times being indistinguishable from households using dug wells - indicating a decline in water quality from source to point-of-use. Chemical treatment at point-of-use is suggested as an appropriate solution to eliminating any post-source contamination. Additionally, it is recommended that future work be done to modify existing water development strategies to consider water quality at point-of-use.
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The primary objective of this project was to determine the impact of appropriate rates of swine manure applications to corn and soybeans based on nitrogen and phosphorus requirements of crops, soil phosphorus accumulation, and the potential of nitrate and phosphorus leaching to groundwater. Another purpose of this long-term experimental study was to develop and recommend appropriate manure and nutrient management practices to producers to minimize the water contamination potential and enhance the use of swine manure as inorganic fertilizer. A third component of this study was to determine the potential effects of rye as a cover crop to reduce nitrate loss to shallow ground water.
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Peer reviewed
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Mode of access: Internet.
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Mode of access: Internet.
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Mode of access: Internet.
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The city of Marion has applied to the Illinois EPA for Section 401 water quality certification to construct a 1,172 surface acre, raw water impoundment reservoir on Sugar Creek, southeast of Creal Springs, Williamson County, Illinois. This proposal and the impacts are described in the Final EIS, DSI, and DSII. The proposed project will involve the construction of a reservoir on Sugar Creek and the mitigation for affected wetlands and jurisdictional waters of the United States.
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The approved project allows the Corps to dredge the Waukegan Harbor approach channel and advanced maintenance area. The area to be dredged lies immediately east of the north breakwater. It is approximately a rectangle 650 feet north and south and 1,400 feet east and west. The advanced maintenance area is a band along the north side of the channel. The approved project is for a 10-year certification, under which the Corps may remove 22,000 to 75,000 cubic yards of sediment per dredging event. The dredging depth is 22 feet and the amount to be dredged is about one foot of sediment. As a condition of the certification, disposal of the dredged sediment in Lake Michigan or the waters of the state cannot occur until the conditions of the certification are met. These conditions, which have been placed on the certification by Illinois EPA, ensure that the project meets state water quality standards and is consistent with the determinations of the Illinois Attorney General's Task Force on asbestos contamination at Illinois Beach State Park.
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"Presented at the Water quality management training course conducted by the Water Supply and Pollution Control Training Program, Robert A. Taft Sanitary Engineering Center, Cincinnati, Ohio, March 4, 1963."
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