published_or_final_version / Botany / Master / Master of Philosophy

The body of work presented in this Thesis document provides a comprehensive examination of final cover design for municipal solid waste landfills. Accompanying general design principals is the investigation and resulting recommendations for issues specific to the closure of the Vancouver Landfill. The first objective of the Thesis was to develop a set of physical characteristics for soil materials, which would allow for the construction of a lowpermeability barrier layer meeting British Columbia guidelines. The second objective was to then use the developed soil criteria to evaluate the suitability of Lower Mainland soils. The physical characteristic of soil material, originating from trench excavations in Vancouver, was closely examined and the material evaluated for use in all layers of final cover design. The last objective of the Thesis was to investigate the use of alternative cover materials, including geosynthetics, in final cover design. The combination of a comprehensive literature review and the implementation of a program of soil sample collection and analysis allowed for the completion of the above objectives. Testing of soil samples included the determination of the grain size distribution to the clay fraction level. The major findings of the work are that soil sources in the City of Vancouver are not suitable for use in the construction of a low-permeability barrier layer. Suitable soil sources however, can be found in areas of Surrey and Langley. Trench excavation soil is recommended for use in the foundation layer of the final cover. Lastly, geosynthetic materials are a viable alternative to the use of soil in final cover design. A polyvinyl chloride (PVC) geomembrane would be the most suitable geosynthetic based barrier layer for the requirements of the Vancouver Landfill.

Despite its phasing out in numerous countries, such as Germany and the U.S.A., co-disposal of hazardous waste with municipal solid waste continues to be widely practised in South Africa. Co-disposal utilises properties and microbial activities in the refuse to attenuate the hazardous waste and thus obviate its environmental impact potential. All landfill operations require careful planning in not only site selection criteria but also the type and amount of various wastes accepted for disposal. It is clear, however, that the practice of co-disposal requires special precautions and management as the methods employed in the landfill operation determine to a large extent the environmental effects and, thus, the public acceptability of the operations. Although co-disposal is not suitable for all industrial wastes the results of recent research efforts, conducted mainly in the U.K., have indicated that, when properly managed, co-disposal can be regarded as a safe and efficient disposal option for many hazardous wastes. Environmental awareness in many European countries ensures that numerous hazardous compounds are either recycled or recovered. Unfortunately, in South Africa the lack of similar concern has resulted in increased concentrations of toxic compounds being co-disposed on a regular basis. Since fundamental studies of this technology, pertaining to South African conditions, have been lacking laboratory models/microcosms were built to address this paucity. Model. To effect the separation of species habitat domains of component species of growth rate-dependent interacting microbial associations responsible for terminal catabolic processes of the refuse fermentation, with retention of overlapping activity domains, and so facilitate examination of species in isolation without violating the integrity of each association, multi-stage models were constructed. The accidental overgassing of the culture with liquid petroleum gas (LPG) effected interesting fermentation balance changes which also emphasised the need for an Anaerobic Bioassay Test to assess the impacts of specific perturbants. Evidence of differential susceptibility of the component species to phenol was demonstrated in this study. Microcosm. A total of 42 refuse packed single-stage glass column bioreactors were commissioned and subjected to phenol and/or anaerobically digested sewage sludge codisposal. The effects of four different operational modes: leachate discard (single elution); leachate recycle; batch; and simulated rain on the co-disposals as well as refuse catabolism per se were examined. The results of these studies indicated that protracted periods of adaption to phenol (1000 and 2000 mg l -1) could have resulted from nutrient (elemental) limitation. Circumstantial evidence was also gained which indicated that the nitrate- and sulphate-reducing bacteria (SRB) were particularly sensitive to the added xenobiotic. Further, without the effective participation of the nitrate- and SRB the active and total fermentation of both the phenol and refuse components were depressed. It was also determined that the operating regime employed was a key factor in refuse degradation although with time, and especially following the phenol resupplementations, the operating conditions played a less significant role. In general, the single elution operated columns demonstrated increased phenol removal rates which were, unfortunately, coincident with low pH values and increased leachate residual phenol concentrations. Leachate recycle, on the other hand, unlike the batch operated columns, facilitated increased pH values and methane evolutions. The simulated rain columns were characterised by rapid washout of the added phenol as well as methanogenic precursors. The sewage sludge co-disposal experiments, likewise, demonstrated that, depending on the sludge:refuse ratio, the operating regime was extremely important in optimising the refuse degradation processes although, in general, leachate recycle appeared to be the most favoured method of operation. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1996.

Rehabilitation of landfill sites is important for successful land utilization. Revegetation is one key element of the process since it can overcome aesthetic problems. The inimical challenges of landfill leachate and gas are largely responsible for the difficulties associated with the revegetation of completed sites. Many components of landfill leachate can be catabolized by microbial associations thereby reducing their impacts on the environment. The importance of research on interactions between pollutants, microorganisms and soil is its applicability in environmental risk assessment and impact studies of organic pollutants which enter the soil either accidentally or intentionally. The application of image analysis with microscopy techniques to landfill soil-pollution interactions provides a means to study surface microbiology directly and to investigate microbial cells under highly controlled conditions. This research focused on the development of a method to study the real time processes of attachment, establishment, growth and division of microbial cells/associations in site covering soils. Image analysis provides a powerful tool for differential quantification of microbial number, identification of morphotypes and their respective responses to microenvironment changes. This minimal disturbance technique of examining visually complex images utilizes the spatial distributions and metabolic sensitivities of microbial species. It was, therefore, used to examine hexanoic acid catabolizing species, both free-living and in a biofilm, with respect to obviating the threat of hexanoic acid to reclamation strategies. The three sources of inoculum (soil cover, soil from the landfill base liner and municipal refuse) were compared for their ability to provide associations which catabolized the substrate rapidly. During the enrichment programme the inocula were challenged with different concentrations of hexanoic acid, a common landfill intermediate. From the rates at which the substrate was catabolized conclusions were drawn on which concentration of hexanoate facilitated the fastest enrichment. The results of initial batch culture enrichments confirmed that the soil used contained microbial associations capable of catabolizing hexanoic acid at concentrations < 50mM, a key leachate component. Exposing the landfill top soil microorganisms to a progressive increase in hexanoic acid concentration ensured that catabolic populations developed which, in situ, should reduce the phytotoxic threat to plants subsequently grown on the landfill cover. The analysis of surface colonization was simplified by examining the initial growth on newly-exposed surfaces. The microbial associations generated complex images which were visually difficult to quantify. Nevertheless, the dimensional and morphological exclusions which were incorporated in the image analysis software permitted the quantification of selected components of the associations although morphology alone was inadequate to confirm identification. The effects of increasing the dilution rate and substrate concentration on the growth of surface-attached associations in Continuous Culture Microscopy Units (CCMUs) were examined. Of the five dilution rates examined the most extensive biofilm development (9.88 jum2) during the selected time period (72h) resulted at a dilution rate of 0.5h' (at 10mM hexanoic acid). The highest growth (608 microorganisms.field"1) was recorded in the presence of 50mM hexanoic acid (D = 0.5h"1). To ensure that the different morphotypes of the associations were able to multiply under the defined conditions a detailed investigation of the component morphotypes was made. Numerically, after 60h of open culture cultivation in the presence of 50mM hexanoic acid, rods were the predominant bacterial morphotypes (43.74 field'1) in the biofilms. Both rods and cocci were distributed throughout the CCMUs whereas the less numerous fungal hyphae (0.25 field'1) were concentrated near the effluent port. The specific growth rates of the surface-attached associations and the component morphotypes were determined by area (//m2) colonized and number of microorganisms.field"' and compared to aerobic planktonic landfill associations. From area determinations ( > 0.16 h'1) and the number of microorganisms.field"1 10mM hexanoic acid was found to support the highest specific growth rate ( > 0.05 h"1) of the surfaceattached association isolated from municipal refuse. With optical density determinations, the highest specific growth rate (0.01 h'1) was recorded with 25mM hexanoic acid. The surface-attached microbial associations component species determinations by area and number showed that the hyphae had the highest specific growth rate ( > 0.11 h"1). The surface-attached microbial association specific growth rate determinations from the discriminated phase (0.023 h'1), area colonized (0.023 h"1) and number of microorganisms (0.027 h"1) calculated from the results of the component species rather than the association should give more accurate results. The specific growth rate obtained differed depending on the method of determination. Any one of these may be the "correct" answer under the cultivation conditions. Depending on the state (thickness) of the association (free-living, monolayer or thick biofilm) the different monitoring methods may be employed to determine the growth. As a consequence of the results of this study, the kinetics of microbial colonization of surfaces in situ may be subjected to the same degree of mathematical analysis as the kinetics of homogeneous cultures. This type of analysis is needed if quantitative studies of microbial growth are to be extended to surfaces in various natural and artificial environments. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.

Efforts by designers to produce solutions to environmental problems has become increasingly sophisticated. Inter-disciplinary teams of designers, engineers and scientists have proposed new and dynamic resolutions to environmental disturbances. There is a problem, however, in the ability of such proposals to be accepted and implemented.This study investigated the possibility that communication of these plans has been responsible for the lack of acceptance. Citizens and governmental officials must adequately comprehend the proposed solutions before they can gain confidence and judge them worthy of implementation. This study searched for aspects of communication necessary to successfully promote pre-planning and reclamation for correcting and preventing environmental problems in sanitary landfills.A random survey of Delaware County, Indiana established base means for concerns (aesthetic, pollution, property value, safety, etc.) in a typical population cross-section. The net effectiveness of the landfill presentation (communication) effort was to be inferred through noted changes in the level of concern between the typical population and the test group who witnessed the educational presentation.The comparative test could not proceed. The focus of this study was then directed towards more intimate analysis of the attitudinal data provided in the cross-sectional survey. A number of obvious and obvious characteristics were revealed.In the end, this study has provided significant insight into the "posture" of the most important link in convincing that planning and design solutions can mitigate environmental problems. That link is at the receiving end of such communication efforts... the "public" with its constructs of fears and biases. / Department of Landscape Architecture

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (M. Env. St.)--University of Adelaide, Mawson Graduate Centre for Environmental Studies, 1993. / Includes bibliographical references (leaves 142-161).

Thesis (M. Sc.)--University of Hong Kong, 1995. / Includes bibliographical references (leaves 89-91).

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Poverty and unemployment in the rural areas of the Eastern Cape is forcing thousands of vulnerable people into waste picking. There is growing recognition that waste re-claimers contribute to the local economy, to public health and to environmental sustainability. However, they often face low social status, tragic living and working conditions, and little support from local governments. The waste reclaimers of the Raymond Mhlaba Municipal area are unemployed, experiencing a poorer quality of life and feeling even more socially and economically excluded from the rest of society because of the “limitations” on landfill salvaging currently. Moreover, they have developed feelings of resentment and anger that have resulted in defiant acts of trespassing and theft. This social development study highlights the implications of landfill closure for waste salvagers in Raymond Mhlaba Local Municipality. Landfilling has been the main method for municipal waste disposal in Raymond Mhlaba Local Municipality. To combat the effects of uncontrolled release of landfill gases, the uncontrolled release of leachate that may affect water quality many landfills in the Eastern Cape are being considered for close down and for rehabilitation. To consider as well is the socio-economic backlog and anticipated population growth in the province, which means that landfill salvaging will continue to be an important source of revenue for the poor and homeless. This research used observation, semi-structured one-on-one interviewing, focus group interviewing and questionnaires as well as conducted a review of waste management policy-related documents and secondary data analysis in this qualitative research to analyse the social and the economic impacts. The research found that waste reclaimers in the Raymond Mhlaba Local Municipality area disagreed with the closure of the Fort Beaufort landfill because of what the researcher assumed to be a lack of general environmental awareness and because of their vulnerability to poverty. Research findings also highlight that waste reclamation can be considered as a viable option to minimize waste at landfills and waste reclaimers have shown an increasing interest and commitment to being trained formally to continue reclamation work. This study has suggested disadvantages in rural landfill closure, without feasible alternatives. Focus must move away from extending waste collection and closing down landfills and instead improve final disposal and initiating minimisation- recycling programs as part of their strategies through the formation of waste cooperatives. This research suggests formalizing and controlling waste recovery to cater for the immediate and most basic needs of the poor. The recommendations will hopefully influence thinking about waste management policy planning and implementation in general, and be of service to furthering Raymond Mhlaba Local Municipality achieve goals of sustainable employment creation and poverty alleviation.