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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.
1

The efficiency of the Zeekoegat artificial wetland as a biological filter of waste water

11 September 2013 (has links)
M.Sc. (Aquatic Health) / Located largely in a semi-arid part of the world, South Africa’s water resources, in global terms are extremely scarce and limited. (South Africa is one of the 30 driest countries of the world). South Africa is already categorised as water stressed with annual freshwater availability of less than 1700 mm³ /person (the index for water stress) (Blignaut and Van Heerden, 2009). South Africa is a water scarce country due to low rainfall (less than 500 mm per annum, some parts less than 200 mm: the average of 475 mm is well below the global average of 860 mm p/a.) and due to the uneven distribution of its water resources (more than 60% of the river flow arising from only 20% of the land area) which is a direct result of the climate and topography of the country (Davis and Day, 1998). South Africa is a large piece of land, far larger than for instance Germany (population of 82.7 million- Bergman and Renwick, 2003). When compared, Germany has 2169 cubic meters of water available per person while South Africa has only 1208 (Bergman and Renwick, 2003). Compared with another arid country, Australia has a population of 19.1 million and freshwater resources of 18 722 cubic meters per person (Bergman and Renwick, 2003). South Africa has close to the lowest conversion of rainfall to usable run-off from rivers of all the countries in the world (South Africa 8.6%, Australia 9.8%, and Canada 66%) (Bergman and Renwick, 2003). South Africa will also be negatively impacted by both changes in climate and the prevalence and spread of alien invasive species (Blignaut and Van Heerden, 2009). Prosperity for South Africa depends upon the sound management and utilisation of many resources, with water playing a pivotal role. Any decrease in the quality and therefore the usability of water in South Africa by 1% may result in the loss of 200 000 jobs, a drop of 5.7% of disposable income per capita, and an increase of 5% or R18.1 billion in government spending. This will further result in a 1% decrease in the GDP growth rate (Du Toit, 2010). This is reiterated by a number of other studies.
2

A Study on Health Assessment Indicators of Artificial Wetlands: Zo-Zai Wetland Park in Kaohsiung, Taiwan as the Case

Chen, Cheng-ying 08 September 2005 (has links)
The disappearance of the wetlands of Taiwan have reflected all kinds of biological drifting about aimlessly. We have to take action for protecting the wetlands, due to there are less than before. In the face of the wetlands that there are not much left, we must treasure and offer protection. The action that a lot of wetlands protection at present is going on. We need to invest more research and monitoring, and should investigate the state of wetland health that file, expect that can utilize limited resources more effectively during the process of protecting. This research expects to build the index system constructing out a set of Taiwan wetlands and assessing to the characteristic of the wetland of Taiwan. After consulting the domestic and international relevant index system, this research drafts preliminary wetland health assessment system. Through Delphi method, gathering opinions and suggestions from experts and scholars this research could set up the health assessment indicators of Taiwan artificial wetlands. Index system is divided into environment and management two general parts, and is categorized into six major indexes groups, including organism, water, soil, environment, management and social economy, amounts to 18 indexes. In the case of Zo-Zai Wetland Park, in Kaohsiung, Taiwan, we applied this index system to inspect the health degree of Zo-Zai Wetland Park and its index results. Assessing the result for being 'good' in health, and cause the unhealthy projects of wetland include restoration species grow up degree, the distribution of the invasive species, the water quality situation, the hydrology situation and the maintenance funds of the wetland . The whole but the speech, the continent Zo-Zai Wetland Park still belongs the health, but influence the wetland healthy factors still need to monitor continuously in order to maintain wetland health quality. This research hopes to diagnose the health state of the wetlands, through health assessment indicators system and regular wetland monitoring, Then designing the wetland follow-up planning and management strategies to result the wetlands¡¦ problems earlier. Finally, it hopes to help restoring the wetlands in Taiwan.
3

Evaluation of a Constructed Wetland to Reduce Toxicity from Diazinon at the Pecan Creek Wastewater Treatment Plant, Denton, TX

Baerenklau, Amy L. (Amy Lyn) 05 1900 (has links)
The City of Denton Pecan Creek Wastewater Treatment Facility has periodically failed effluent toxicity testing. A Toxicity Identification Evaluation has determined that Diazinon in the effluent is contributing to the observed toxicity. Chlorpyrifos is also implicated as a factor. The City of Denton constructed a half acre experimental wetland to remove Diazinon related toxicity. Results from spiking and microcosm experiments indicate that the wetland can reduce the Diazinon.

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