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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.
111

Access and Alteration Rules Related to Significant Wetlands

Miller, Justin 11 May 2012 (has links)
This study sought to explore the access and alteration “rules experience” within an Ontario wetlands case study framework. The study interviewed two key stakeholder groups, key-involved stewardship agencies and key-identified wetland property owners, and aggregated them as a single response group. There were significant overlaps between these groups and the final identified potential respondent group was thirteen. All potential respondents were invited to participate in a detailed exploration of the rules experience via a thorough semi-structured interview process within the existing context of a Long Point, Ontario study area. For their own specified reasons, eight of thirteen identified and invited potential respondents chose to provide a response for analysis. It was imagined that very specific questions about each discovered rule in the study area might provide insight into to effect and understanding of specific rule characteristics within the study area; however, nothing exceptional was revealed with respect to rule characteristics using a small detailed study group. Study area respondents appeared to have focused and specific knowledge of a collection of study area rules (often within their direct interest), but few respondents had a relatively comprehensive knowledge of the entire alteration and access rules framework. The most interesting results within in the interview process, including the most interest in response provision by respondents, centred more generally on wetland management- with emphasis on private and public management initiatives. In this theme, while generally supportive of the apparent goals of the existing rules, respondents were divided as to how management should actually function within the study area. Despite interest by both key informant groups in wetland conservation and maintenance, the application of public rules on private and/or organized wetland spaces occasionally appear to conflict. During the study, there appeared to be much more interest in wetland alteration rules, and, expectedly, a strongly expressed desire to have these rules more carefully scrutinized and adapted to the study area. The study area is fortunate to have a history of public and private interest in wetland conservation; this study highlights the need for these similarly interested groups to work together to reconcile the differences in expected applications of public rules.
112

The Amenity Value of Wetlands

Gao, Shan 16 December 2013 (has links)
Wetlands provide recreation and cultural values including scenic views, aesthetics, open-spaces, and leisure opportunities to surrounding residents. This study applies a hedonic approach to estimate the impact of wetland amenities on nearby single family homes using actual sales prices of properties from 1991 to 2005 in Chatham County, Georgia, where wetland resources are unevenly distributed in terms of types and quantities of wetlands. Separate hedonic models are investigated to understand the spatial variation of wetland amenity effects across different study areas in Chatham County. This study finds that wetland amenity values vary mainly with the characteristics of study location. In a rural setting where wetland resources are ample and sufficient. Wetland amenities have negative impacts on the sales price of nearby single family homes. Forested wetlands, the size of the nearest wetland, and wetland proximity negatively impact the sales price of the properties. In an urban setting where wetland resources are extremely limited, wetlands have significant positive amenity effects. The size of the nearest wetland positively impact the sales price of nearby single family homes, but type of wetlands turns into insignificant. In a suburban area with diverse wetland recourses in term of types of wetlands, mixed amenity effects are found. In general immediate access to a wetland, especially a large size one, positively impact nearby single family homes. Type of wetlands plays a key role in deciding the direction and magnitude of wetland amenity effects in a suburban area. The findings of the study suggest that policy makers need to think about both the characteristics of wetlands and their spatial context when providing or protecting wetland amenities.
113

Quantification of complex phosphorus removal reactions occurring within wetland filtration treatment systems

Sikdar, Anamika 20 December 2007 (has links)
In a constructed treatment wetland applied to domestic wastewaters, long term studies and increased operational experience indicate that phosphorus removal is variable or inconsistent, especially in cold-climate applications. These inconsistencies can be attributed to the complexity of phosphorus removal mechanisms, and the lack of consideration of these complexities in the design, installation and operation of these treatment systems. Sorption of phosphorus to the wetland media is generally considered to be the major removal mechanism. The research described in this thesis was conducted to determine the most suitable material for application in a constructed wetland and a post wetland-filter to treat phosphorus in wastewater effluents, taking advantage of sorption processes. The present work was conducted at lab (bench) scale. Three potential sorptive media were studied in the research program, namely gravel, slag and clinker. Several methods for media analysis were investigated as potential screening tools for media selection. To determine the various forms of phosphorus in the media, sequential extraction tests were considered to be most relevant and useful for this research. Batch testing and flow cell testing along with sequential extraction tests were conducted to predict the sorption capacity and performance of the media for the long term (10+ years) removal of phosphorus. The protocols developed in this thesis permitted a rigorous assessment of the media and should be applied in any assessment of sorptive media to select the best medium. Gravel showed some sorption of phosphorus although it was not sufficient to meet the regulatory limits for the effluent concentration. Clinker and slag showed high sorption capacity as compared to gravel and the observed effluent concentration was below the regulatory limits. All three media showed the presence of background phosphorus, with clinker having the highest amount of background phosphorus. However, except gravel, clinker and slag did not show any significant amount of phosphorus being leached out during low phosphorus loading conditions. Taking all factors under consideration, slag and clinker were identified as good media for phosphorus removal. Media that have proven to have high sorption capacities and also retention capabilities should be considered for applications where phosphorus removal is the prime objective. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2007-12-10 11:40:49.657 / NSERC
114

Microbial and Organic Matter Characteristics of Restored Riparian Soils

Card, Suzanne M. Unknown Date
No description available.
115

An experimental research on application of sub-surface flow constructed wetlands for meat processing industry effluent treatment and nutrient removal

rkurup@murdoch.edu.au, Rajendra Kurup January 2007 (has links)
Meat processing industries produce large volumes of high strength wastewater. Conventional technologies used in Australia and similar countries for treatment of effluent from meat processing and similar industries, such as wineries and processed food industry, are treatment ponds with or without a mechanical treatment system. A properly designed activated sludge treatment system would be capable of biological removal of phosphorus and nitrogen in addition to BOD5. These systems, however, require substantial electrical power, skilled operational support and produce large quantities of biosolids or sludge which require further on-site treatment or off site disposal. Application of sub-surface flow constructed wetland (SSF-CW) systems could provide a sustainable solution for treatment of meat processing industry effluent and other similar high strength wastewaters. There are, however, only very limited studies on application of SSF-CW for secondary treatment of high strength wastewaters. Although there have been a number of cases where SSF-CW have been used as the secondary treatment unit for municipal wastewater, this technology has not still become a common practice for the same purpose in Australia. Most of the applications are for either polishing of secondary or tertiary treated municipal wastewater or for greywater treatment. This research was funded by National Meat Industry Advisory Council (MINTRAC). Sustainable wastewater treatment has been taken up as a very important issue by meat industry. The industry provides Ph.D research scholarships through MINTRAC to develop new technologies for wastewater treatment and nutrient removal from meat processing effluent. The main objective of the research was to develop process engineering design parameters for sub-surface flow constructed wetland (SSF-CW) with Monto vetiver (Vetiveria zizanioides recently reclassified as Chrysopogon zizanioides) as the emergent vegetation for treatment of high strength, nutrient rich wastewater. The study also investigated the phosphorus retention properties of pea gravel for use in SSF-CW system as bed media or as an external phosphorus removal system for meat processing industry effluent. In addition, chemical methods for phosphorus removal from meat processing industry effluent were also investigated. The thesis is based on experimental research. The research consisted of three types of experimental set up; a) using two laboratory experimental SSF-CW reactors (one with vetiver grass and the other reactor with no vegetation) in a greenhouse with batch feeding of artificial wastewater that simulates meat industry effluent, b) experiment with pea gravel of different particle sizes and solutions of different phosphorus (P) concentrations in a constant temperature room, c) laboratory experiment using actual meat processing industry effluent with alum and sodium aluminate for P removal. The structure of the thesis is as follows. Following the Introduction is the section of Literature Review, then sections on the experiments that follow a journal paper format, followed by a General Discussion, Conclusions and Recommendations. A list of references is provided at the end of the thesis. The literature review section has four chapters (Chapter 2 to Chapter 5). Chapter 2 describes a review of meat processing industry effluent characteristics and current treatment technologies. Chapter 3 is a critical review of current literature on COD removal using sub-surface flow constructed wetlands (SSF-CW). Chapter 4 and 5 describe a review of various processes and models on the fate of nitrogen and phosphorus in SSF-CW system respectively. Chapters 6 to 10 deal with experimental research part of the thesis. Chapters, 6, 7 and 8 share a common methodology section which is described in Chapter 6. Results of the batch experiments with the laboratory SSF-CW systems on COD removal, nitrogen removal and phosphorus retention are discussed in Chapters 6, 7 and 8 respectively. Chapter 9 explains a detailed experimental study on phosphorus adsorption dynamics of pea gravel. Chapter 10 discusses the results on experiments using sodium aluminate and aluminium sulphate for P removal from meat processing industry effluent as an alternate P removal method for such effluent. An overview of the major results of the experimental section is discussed in chapter 11, in the General Discussion section. Conclusions and Recommendations of the research are provided in Chapter 12. In this study, it was observed that Monto vetiver grass performed better during nitrification than in denitrification, where the plant did not survive. Ammonium N removal followed a first order decay in both vegetated and un-vegetated experimental SSF-CW system with average removal ranging from 40 to 60 % of the influent. Denitrification was found to be the pathway for nitrate removal. As long as the carbon source was available, the denitrification followed a first order exponential decay, with over 80% of nitrate was removed in 48 hours. Vetiver grass sustained elevated ammonium levels of approximately 200 mg/L or more, however it was under stress during denitrification and it eventually died. The experimental SSF-CW systems with pea gravel as bed media could effectively retain soluble reactive phosphorus (SRP) in the wetland cells during experiments of COD reduction and nitrification (with ammonia and high COD input). However, during denitrification study, both experimental SSF-CW cells did not show significant removal of SRP from wastewater. The vegetated cell removed nearly 50% of the input SRP, however, the un-vegetated cell did not show any trend for SRP removal, and in some cases the effluent SRP was nearly 90% of the input value. The role of Monto vetiver grass for N and P removal was found to be very minor and this study concluded that nutrient removal (N & P) by plant uptake could be neglected in the design of SSF-CW system with Monto vetiver grass. Adsorption is the major mechanism for P removal from the experimental SSF-CW systems, where pea gravel was used as bed media. The P adsorption capacity of pea gravel increased with decrease in particle size. For 16 to 18 mm, the Langmuir adsorption maximum was 99 mg/kg, whereas for very fine pea gravel powder (<150 ìm) the maximum adsorption observed experimentally was 3950 mg/kg. In a typical wetland with pea gravel as bed media for meat processing industry, the media would be capable of P retention for about 2 to 3 years of operation. Supplementary chemical removal method is needed for sustainable P removal once the adsorption maximum of wetland cell is reached. A chemical P removal system using liquid alum and NaOH for pH stabilisation is more appropriate than sodium aluminate. Application of sodium aluminate for P removal for meat processing industry effluent is found to be less effective as it would need higher dosage, longer settling period, coloured supernatant, acid addition for pH adjustment. Liquid alum application rate is recommended to be between a molar ratio of Al: P of 3 for TP value of <1 mg/L in the treated effluent. This research study concludes that horizontal flow SSF-CW system with Monto vetiver grass is suitable for COD removal and nitrification from high strength wastewater. Current design equation of horizontal flow SSF-CW system is mostly plug flow exponential decay method, but in this study, it has been concluded that retarded first order rate constant is the most appropriate design method for horizontal flow SSF-CW system for COD removal.
116

Influence of pollutant loading rate on seasonal performance of model constructed wetlands

Schultz Jr., Rickey Lynn. January 2007 (has links) (PDF)
Thesis (M.S.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Otto Stein. Includes bibliographical references (leaves 41-43).
117

Periphyton-nutrient dynamics in a gradient-dominated freshwater marsh ecosystem

Scott, J. Thad Doyle, Robert D. January 2006 (has links)
Thesis (Ph.D.)--Baylor University, 2006. / In abstracts "- and 2" are superscript. In abstracts "3 and 2" are subscript. Includes bibliographical references (p. 105-114).
118

The use of constructed wetland systems for wastewater treatment : nitrogen transformation and indicator bacteria removal /

McKersie, Sue A. January 1991 (has links)
Thesis (M. Sc.)--University of Western Sydney, Hawkesbury, 1991. / Includes bibliographical references.
119

Habitat classification with reference to flooding and salinity, to assist with the vegetation of a saline artificial wetland /

Hunter, Sally Ann. January 1998 (has links) (PDF)
Thesis (M. Env. Sc.)--University of Adelaide, Mawson Graduate Centre for Environmental Studies, 1999. / Includes bibliographical references (leaves 104-110).
120

Mangrove wetlands in Bangladesh /

Begum, Fatema. January 1998 (has links) (PDF)
Thesis (M. Env. Sc.)--University of Adelaide, Mawson Graduate Centre for Environmental Studies, 1998. / Includes bibliographical references (leaves 65-71).

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