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  • 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.
11

Wetlands and their use as wastewater treatment systems /

Fromal, Barbara L., January 1994 (has links)
Report (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 87-91). Also available via the Internet.
12

Anthropogenic natures : Wicken Fen and histories of disturbance 1923-1943

Cameron, Laura Jean January 2000 (has links)
No description available.
13

Chemical engineering modelling of a vegetated submerged reedbed for winery effluent treatment

Sheridan, Craig Michael 25 February 2014 (has links)
Environmental concerns for wineries in South Africa cover not only the conversion of effluent into more benign forms, but the reclaiming of water, a resource that is scarce and precious in a drought-prone country. However, not all waste treatment options are available to small wineries, because many are too sophisticated and expensive to be commercially viable. Accordingly, this study investigated the use of constructed wetlands in the form of Vegetated Submerged Reedbeds (VSR) as a practicable alternative for small-scale wine producers. Winery effluent is known to have a high chemical oxygen demand (COD) and low pH. In this study, effluent was extensively analysed from two cellars, including the temporal changes over the duration of a harvest and the duration of a year. It was found that for raw winery effluent, ethanol contributes approximately 85% to 90% of the COD, with acetic acid being the next significant contributor. The pH showed some dependence on the concentration of acetic acid. The concentration of sodium in the effluent is strongly dependent on the cleaning regime in place at the cellar, and the concentration of potassium has been shown to be linked to the spillage of juice, wine or lees. It was also found that the hydraulic processes occurring within the VSR display significantly non-ideal behaviour. If the feed to the VSR was located on the surface the dead volume accounted for approximately 25% of the non-ideal behaviour of the system and bypass accounted for a further 6% of non-ideal behaviour. In the system studied, there was a preferential flow pattern within with the greatest flow occurring closest the surface and in the centre, and the least at the sidewalls. It was proposed that the flow profile can be conceptualised as being hull-shaped. We believe this hypothesis is correct and as far as we are aware this flow pattern has not been described previously. It was found that this profile was the same for irregularly shaped gravel and for spherically shaped gelatinous beads and it is therefore believed it is not dependent on the geometry of the VSR or the packing medium. This study also investigated the use of three different methods for determining the rate constants for the degradation of winery effluent within a sub-surface flow constructed wetland (CW). These methods comprised using a dispersed plug flow (the Peclet) equation; a tanks-in-series (TIS) equation; and analysing the residence time distribution (RTD) directly. The last of these was called the Convolution Integral (CI) method. Within the CW studied, the principal constituent of the chemical oxygen demand (COD), ethanol, was always fully degraded by the time the flow reached the outlet. It was therefore possible to calculate the rate constant of degradation from the initial eight metres of the CW. Self similarity of the RTDs was also demonstrated, which meant that in general the system’s hydraulics were similar throughout the CW. This meant we could extrapolate the data so as to develop a more complete understanding of the hydraulic properties of the CW and examine how they affected the kinetics of degradation. It was found that whilst both the Peclet and the TIS equation were able to predict concentration within the CW accurately, this required multivariate optimisation. This rendered a result that was more of a modelling exercise than a useful design tool. The CI method, however, could be applied to predict system parameters effectively. This study used the CI to measure the rate constants of removal for both ethanol and potassium, which were found to be the key species that responded to the degradation/treatment of the effluent. The rate constant found for the biodegradation of COD was found to have significantly more uncertainty associated with it than the measurement of the rate of degradation individual components and it was therefore posited that it is better to describe the processes of degradation by tracking individual components rather than lumped parameters. In each chapter, a short abstract is provided in which results are given.
14

Mitigation of harvesting disturbances on a forested wetland in the South Carolina lower coastal plain /

Scheerer, Greg Alan, January 1900 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 80-91). Also available via the Internet.
15

Monitoring and modeling the hydrology of a forested sinkhole wetland on the Tennessee Highland Rim : a dissertation presented to the faculty of the Graduate School, Tennessee Technological University /

Hill, Andrew Jason, January 2007 (has links)
Thesis (Ph.D.)--Tennessee Technological University, 2007. / Bibliography: leaves 206-211.
16

Development and testing of a procedural model for the assessment of human/wetland interaction in the Tobari System on the Sonoran Coast, Mexico /

Valdés-Casillas, Carlos. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 1997. / Typescript (photocopy). Includes bibliographical references (leaves 126-142). Also available via the World Wide Web.
17

The developmental history of a wetland ecosystem a spatial modeling approach /

Friedman, Robert M., January 1900 (has links)
Thesis--University of Wisconsin--Madison. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 96-98).
18

Sediment methylmercury concentrations and production rates in coastal wetlands of Chequamegon Bay (WI), Lake Superior /

Ogorek, Jacob. January 2009 (has links)
Thesis (M.S.)--University of Wisconsin -- La Crosse, 2009. / Includes bibliographical references (leaves 50-55)
19

Remote identification of wetlands in Mahoning and Trumbull County, Ohio

Krzys, Bethaney L. January 2008 (has links)
Thesis (M.A.)--Kent State University, 2008. / Title from PDF t.p. (viewed Dec. 22, 2009). Advisor: Mandy Munro-Stasiuk. Keywords: remote sensing, wetland, wetland identification, GIS. Includes bibliographical references (p. 158-161).
20

Created wetlands in Shing Mun River, Sha Tin /

Lin, Wai-tung. January 1999 (has links)
Thesis (M.L.A.)--University of Hong Kong, 1999. / Includes special study report entitled: Create freshwater wetlands. Includes bibliographical references.

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