Thesis (DTech. degree in Environmental management.)-Tshwane University of Technology, 2008. / Aims to determine the presence and levels of common polybrominated diphenyl ethers primarily in landfill leachates, but as well as sediment and groundwater (boreholes / wells around the landfill) from selected landfill sites in order to provide baseline data required to protect water resources against such chemicals.

published_or_final_version / Civil Engineering / Master / Master of Philosophy

The present study aimed to determine whether stable isotope techniques can be universally applied to detect landfill leachate contamination in aquatic systems. Results of analysis of ��C in dissolved inorganic carbon ([delta]��C-DIC), deuterium and �⁸O in water ([delta]D-H₂O and [delta]�⁸O-H₂O), and �⁵N of dissolved inorganic nitrogen components ([delta]�⁵N-NH₄⁺ and [delta]�⁵N-NO₃⁻) were presented for leachate, surface, and ground water samples collected from seven landfills located throughout New Zealand between 2003 and 2006. The unique conditions within a landfill lead to measurable fractionations in the isotopic ratios of the products of degradation. Results of isotope and ancillary parameter analyses enabled the discernment of different types of leachate, resulting from different microbial processes within the landfill environment. The isotopic characterisation of leachate enabled improved interpretation of geochemical data from potentially impacted surface and ground waters, and provides useful insight to landfill development for landfill operators. A general isotopic fingerprint delineated by [delta]��C-DIC and [delta]D-H₂O values showed leachate to be isotopically distinct from uncontaminated surface and ground water for samples analysed in the present study. However, not all water samples identified as leachate-impacted via site-specific assessments exhibited isotopic values that overlapped with the general leachate fingerprint. This highlights the need to investigate each site individually, within the context of a possibly global leachate isotope signature. Site-specific investigations revealed the effectiveness of applying [delta]�⁸O-H₂O and [delta]�⁵N-NH₄⁺ or [delta]�⁵N-NO₃⁻, in addition to [delta]��C-DIC and [delta]D-H₂O analyses, to the detection of leachate impact on aquatic systems. Furthermore, ancillary parameters such as alkalinity and ammonium concentration enabled the construction of simple isotope mixing models for an estimate of the quantity of leachate contribution. Results of isotopic investigations of stream biota suggested potential for the development of bio-indicators to monitor leachate influence on aquatic ecosystems in landfill-associated streams. The present study demonstrated the probative power of stable isotope techniques applied to investigations of leachate impact on landfill-associated aquatic systems.

Thesis (M.P.A.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves i-v).

Thesis (M.S.)--Brigham Young University. Dept. of Civil and Environmental Engineering, 2007. / Includes bibliographical references (p. 99-100).

Thesis (M.P.A.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves i-v). Also available in print.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (p. 379-394). Also available in electronic version.

Virginia is rapidly running out of landfill space. Recycling is seen as a way to alleviate some of the burden on our landfills. The Commonwealth of Virginia has mandated an ambitious recycling goal of 10% of our municipal solid waste (MSW) by 1991, 15% by 1993, and 25% by 1995. Yardwaste (debris such as leaves, grass clippings and shrub and tree prunings) comprises an estimated 15% to 20% of the municipal solid waste going into our landfills daily. Yardwaste can be recycled by collecting the material, piling it into large windrows, and allowing it to decompose by a controlled process called composting. The finished product can then be utilized as a soil amendment for use by nurseries, landscapers, farmers, local and state government landscaping projects, and by homeowners. The Virginia Cooperative Extension Service at Virginia Tech was authorized to perform a study on the feasibility of implementing a statewide yardwaste composting program for Virginia. The methods involved in the study included information acquisition via a literature review, site visits in other states to assess technologies and a series of surveys to determine potential uses and users of composted yardwaste in Virginia. The feasibility study was presented to the Virginia Department of Waste Management in November 1989 and presented as House Document No. 34 to the 1990 Session of the Virginia General Assembly. Several pieces of legislation, including three bills and one joint resolution, are currently pending concerning the results of the study. / Master of Science

The design characteristics of an active waste disposal capsule placed within a saturated groundwater environment is investigated, with the objective of developing a methodology to determine environmentally, technically and economically feasible conditions for its operation. In operation, conditions are created and maintained within and surrounding a containment cell to insure that a potential for convective inflow exists everywhere across an encapsulating barrier which tends to counter the potential for outward dispersion through the barrier. A computer algorithm based on the finite element method has been developed in the BASIC language to aid in the hydraulic analysis. Essentially, it provides a numerical solution to potential flow through porous media for two dimensional anisotropic solution domains of various materials. Data generated from this algorithm for cases of varying geometric material and boundary properties are used to verify and quantify assumed relationships involving critical design parameters which have been developed through dimensional analysis and physical reasoning. An expression describing the concentration profiles developed across the barrier is obtained by solving the one-dimensional convection-dispersion equation for steady conditions within and bounding the capsule barrier. Applying this result to an identified critical point allows conservative barrier design criteria to be developed so that operation of the active capsule results in only negligibly small amounts of contamination escaping through the barrier to the environment. By introducing cost coefficients which are descriptive of various aspects of construction, operation and maintenance of the active capsule, a total cost function is formulated from which, when minimized with respect to various design variables, optimizing criteria are developed. Finally, a predictor-corrector optimization program which incorporates the results of this study is developed and used to investigate an illustrative problem. / M.S.

published_or_final_version / Architecture / Master / Master of Landscape Architecture