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This case study analyzes the opportunities and potential for a cooperative structure in rural small water systems (SWS) located in Carroll County, Virginia. It is hypothesized that, by organizing as a cooperative, SWS in Virginia can obtain operational efficiency and meet the National Primary Drinking Water Standards (NPDWS) through economies of scale. Specifically, the research involves a market analysis of the factors which influence costs, operational efficiency, revenue, the exchange of technical information, operational capacities, and, thereby, the number of NPDWS violations in those participating SWS. The results of this research reveal ways in which a cooperative structure could result in efficiency and compliance gains. Results are used to develop guidelines for a conceptual cooperative structure that can be applied to SWS across rural Virginia and perhaps may have application on a broader economic and geographic scale. / Master of Science

Please read the abstract in the section 00front of this document / Dissertation (MSc)--University of Pretoria, 2009. / Microbiology and Plant Pathology / unrestricted

This thesis compares the Roman water systems in Pompeii and Nîmes in order to understand the relationship of the water systems to the urban layout of the city. Analyzing the nature and location of an urban water system enables a better understanding of the urban functions within a city, as well as prediction of the nature and location of particular structures within an urban plan. I examine the primary sources of Vitruvius and Frontinus, the topography of each city, the urban orientations, the hydro-technologies employed, and the public and private buildings to which water would have been supplied. My survey of water systems begins with the source of water and the aqueduct that supplies each city and also assesses the relationship of the aqueduct to the rural landscape. In both Pompeii and Nîmes, water from the aqueduct is deposited in a central settling tank within the city and dispersed from the settling tank to various destinations. I have analyzed the buildings, public and private, that had or would have required direct access to this water source and created water supply routes for each colony.

Cooling water systems are generally designed with a set of heat exchangers arranged in parallel. This arrangement results in higher cooling water flowrate and low cooling water return temperature thus reducing cooling tower efficiency. Previous research on cooling water systems has focused mainly on heat exchanger network thus excluding the interaction between heat exchanger network and the cooling towers. The studies completed on cooling water system in which the interaction between the cooling tower and the heat exchanger network was taken into consideration were limited to systems with single cooling tower. The main aim of this study was to develop a design methodology for synthesis and optimization of cooling water systems with multiple cooling towers. The design intends to debottleneck the cooling towers by reducing the circulating water flowrate. The study focuses mainly on cooling systems consisting of multiple cooling towers that supply a common set of heat exchangers. In this work the mathematical optimization technique was developed for optimization and synthesis of cooling water system. The heat exchanger network was synthesized using the mathematical optimization technique. This technique is based on superstructure in which all opportunities for cooling water reuse are explored. The cooling tower model was used to predict the thermal performance of the cooling towers while taking the thermal conditions of the associated heat exchanger network into account. The propose technique debotlleneck the cooling towers by decreasing the circulating water flowrate. This implies that a given set of cooling towers can manage an increased heat load. From the case studies, 22% decrease in circulating water flowrate was realized. The blowdown and makeup were also decreased by 7%. Furthermore, the cooling tower effectiveness was also improved by 4%. A decrease in the overall circulation water has an added benefit of decreasing the overall power consumption of the circulating pumps. There is also a potential for the reduction of makeup and blowdown water flowrate. / Dissertation (MEng)--University of Pretoria, 2011. / Chemical Engineering / unrestricted

Fresh water, particularly potable water, is a critically important, albeit scarce, resource to human beings. Increasing evidence of polluted fresh water bodies indicate water usage patterns that are detrimental to the scarce reserves of fresh water on a regional and global level. It may be said however, that, that the current problems of water wastage and abuse are not merely the results of the technology used but more so of the erroneous perceptions that have guided its development. Therefore it is crucial to not only adopt different technology to solve current water management problems but more important to create a new holistic paradigm of water management that provides the framework for ecologically sustainable technology. The thesis on a circular model of urban hydrology is an attempt in this direction. The thesis is based on the need to develop a sustainable model of urban hydrology. It is a descriptive model that combines existing technologies in a manner that would make them relevant to present and future cities and is applied on a conceptual level to study the implications that this new model could have on the urban landscape. By exploring the concepts of waste water reclamation and re-use, and storm water management that is connected to the city's water supplies, the circular model attempts to attempts to reduce the affects of urbanization and urban water usage on external natural systems while establishing ecologically benign links with the regional and global environments. The use of biological systems for wastewater reclamation has different implications to the urban physical environment in terms of its landuse patterns, open space systems, human activities and aesthetics, than a conventional centralized system of water supply and disposal. The thesis discusses those implications that are particularly relevant to those involved in the planning and design of cities and speculates on an urban environment that might be different from an existing modern city. / Master of Landscape Architecture

This study explores key aspects of water usage in Virginia via a broad-scale analysis of multiple water users through thirty years of time-series records from the Virginia Water Use Data System. A full spectrum of users is considered, including water used for energy, industrial, agricultural and municipal applications. The extent of the relationship between the volume of water used and drivers like economic and climatic conditions are not well defined in humid environments like Virginia. Mann-Kendall testing is applied to identify water use trends through time both statewide and at the county level. A panel regression is employed to identify relationships between water use and explanatory variables of climatic and economic conditions, both spatially and temporally. Key trends include that industrial and energy sector water withdrawals per facility are significantly decreasing over time. Water used for agricultural applications was found to increase on warmer than average years and decrease on wetter than average years, indicating the panel regression methodology successfully demonstrated and quantified intuitive trends. Interestingly, municipal and industrial water usage had a statistically significant relationship with the Gini coefficient, a measure of inequality in rainfall distribution, indicating intraseasonal variability may play an important role in water use trends that is not apparent using seasonal averages alone. Overall, this work contributes to the understanding of water use trends at the state level for Virginia, and better characterizes long-term trends and short-term variability in water withdrawal. / MS

Master of Science / Department of Architectural Engineering and Construction Science / Fred L. Hasler / This paper discusses the advantages of applying a utility centralized chilled water system as the district cooling choice for facilities in the high-density urban areas of China and how it will influence China’s development in the next decades. Presently, the Chinese government is trying to contribute to the world’s energy-saving goals as well as determine its sustainable development framework. As air pollution has become one of the main problems in China, indoor air quality (IAQ) is likely to gain priority as a building design consideration in the future. Consistent with this fact, this paper proposes an optimum HVAC system for cooling purposes to the Chinese government. Compared to unitary HVAC systems, the centralized HVAC system has significant advantages in system efficiency, energy reduction and cost savings and can, therefore, be a better choice. Furthermore, the paper will focus on the centralized chilled water system and demonstrate why they better match the development model in China. The application of the system in high-density urban areas will also be discussed. Due to a lack of understanding that the energy consumption of unitary systems, the first comparison presented is between unitary HVAC systems and centralized HVAC systems in individual buildings. The comparison presented will focus on the energy-saving benefits of the centralized HVAC system in individual buildings and its contribution to sustainable development. Consequently, prescribing a centralized chilled water system as a utility district cooling system and applying a centralized chilled water system to each individual building in the highdensity urban areas will be compared. Cost savings, including initial cost and life cycle cost, are the metrics used in this comparison. Additionally, energy consumption and system reliability will be explored in determining which model will be more appropriate for China's development. The paper concludes that the centralized chilled water system should become the mainstream in the high-density urban area in China. Several recommendations are also made to the Chinese government on setting up utility centralized chilled water systems.