University of Macau / Faculty of Science and Technology / Department of Civil and Environmental Engineering

University of Macau / Faculty of Science and Technology / Department of Civil and Environmental Engineering

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

A series of resonant column and torsional shear (RCTS) and large scale resonant column (LSRC) tests were performed to investigate the dynamic properties (shear modulus and material damping ratio) of municipal solid waste (MSW). the MSW materials were recovered from the Tri-Cities landfill adjacent to the San Francisco Bay in California. A total of 30 specimens 2.8-in. (71.1-mm) and 6.0-in. (152.4-mm) of old, fresh, and mixed MSW were reconstituted in accordance with established sample preparation procedures. Ten of specimens were small-diameter (2.8-in. (71.1-mm)) RCTS specimen and 20 specimens were larger (6.0-in. (152.4-mm)) LSRC specimens. Dynamic laboratory measurements were performed in the linear and nonlinear strain ranges. Test parameters affecting the dynamic properties in the linear range included: (1) duration of confinement, (2) isotropic total confining pressure, [sigma]o, (3) excitation frequency, f, and (4) specimen size. Other test parameters affecting dynamic properties in the nonlinear strain range were: (1) shearing strain amplitude, [gamma], (2) isotropic total confining pressure, (3) overconsolidation ratio, (4) number of loading cycles, and (5) excitation frequency. In addition, the effects on dynamic properties of MSW specimens of material parameters such as (1) waste composition, (2) water content, (3) unit weight of waste, and (4) particle size were evaluated. The total unit weights of old, fresh, and mixed MSW specimens were estimated during testing in the RCTS and LSRC devices. These estimated total unit weights in the laboratory were compared with those measured at other MSW landfills and were found to generally be less than the field measurements. At a given [sigma]o, Gmax decreases with decreasing weight percentage of soil-size (passing the 3/4-in. (19.1-mm) sieve) material. However, Dmin increases slightly with decreasing weight percentage of soil-size material. Another relationship was developed between estimated total unit weight, [gamma]t, and confining pressure, including weigh percentage of soil-size material. The Vs profiles of old, fresh, and mixed MSW specimens obtained in the laboratory tests were compared with those measured at other MSW landfills in situ. The 62 to 76% soil-size material groups are in good agreement with in-situ Vs profiles. The variation in normalized shear modulus and material damping ratio curves were patterned after the Darendeli model (2001) for different weight percentages of soilsize material. An empirical relationship between normalized shear modulus (G/Gmax) and modified material damping ratio (D-Dmin) was developed in the nonlinear strain range. As part of collaborative research project, nonlinear shear modulus reduction and material damping curves generated by The University of Texas at Austin (UT) and The University of California at Berkeley (UCB) were compared according to different weight percentages of soil-size material. Furthermore, nonlinear shear modulus reduction and material damping ratio curves generated by UT were also compared with ones previously proposed by other researchers.

published_or_final_version / Public Administration / Master / Master of Public Administration

No description available.

A number of environmental, social and economic problems are associated with waste disposal in landfill operations. The potential hazards associated with landfill operations are numerous and include fatal accidents, infrastructure damage, pollution of the local environment, harmful air emissions, to simple nuisance problems – such as dust, odour, vermin, and noise pollution. Further challenges include the availability of land and lack of municipal or other financing in the face of rising operation costs. Landfilling is, however, seen by many as an environmentally responsible and cost-effective solution to waste disposal. It is acknowledged however to lead to waste of resources by burying valuable materials that could have been reutilized. Careful engineering can resolve this shortcoming, yet the associated challenges and costs can become prohibitive. The regulatory environment also affects the prospects for adopting this approach to landfill site management in different contexts. The Mariannhill landfill site in eThekwini Municipality, South Africa, provides an opportunity to investigate both the range of challenges which these type of sites encounter, and the solutions which have been developed as a response. The central questions which this research seeks to answer are whether the practices adopted by the Mariannhill landfill site are replicable in other solid waste landfills around eThekwini and whether it can be viewed as an example of best practice in landfill site management more generally. The research finds that the main barrier to easy replication of systems followed at Mariannhill in other landfill sites is the difficulty in replicating the specific structures and character of management. Another key determining factor found is the prevailing attitudes to recycling and the environment in general in the society. Consumers choices are seen to be critical to the prospects for recycling of solid waste, including the size, degradability and recyclable potential of products purchased. In considering the potential for replication of the Mariannhill model as an example of best practice, it becomes clear that the technical aspects of operations at Mariannhill are the most easily replicable, yet other and equally important determinants of success are not easily replicable. These include the existing regulatory environment and prevailing societal attitudes towards recycling. / Thesis (M.T.R.P.)-University of KwaZulu-Natal, Durban, 2009.

Waste management systems are created based on a careful balance of interrelated factors, a variety of players, and diverse political, social, and economic landscapes. The purpose of this study is to identify the impacts to waste management caused by limited supply or increased cost of energy. A case study was created based on the Alberta Capital Region using literature review, surveys and interviews to identify how energy is used throughout the various phases of waste management, from collection through to disposal and diversion, and what the factors are that affect the organization and infrastructure selected for the waste management system. The results of this study conclude that there are economic, social, environmental, political, and decision-making impacts related to an energy crisis. In particular, it was concluded that an energy crisis will cause social and economic stresses that will result in organizational and infrastructure changes to waste management.

Poverty in its many guises - poor housing, no employment, indifferent health and hunger is a driving force for scavenging. In most developing countries, the informal recovery of material from waste is a common survival strategy for the poor. In fact, up to 2% of populations in developing countries depend on recovering, re-using and selling waste materials from streets, dumpsite or landfills for their livelihood. The aim of this study was to develop an understanding of the socio-economic conditions affecting the scavengers and scavenging activities at the Hulene dumpsite in Maputo. This study set out to develop a conceptual framework depicting scavenging, its problems and opportunities. This was used to structure the research. The main issues addressed were: • The driving forces of scavenging where poverty is the major factor. • The organization of scavengers and scavenging activities showing that there is no formal organization of scavengers, which leads to exploitation of vulnerable groups. • The reaction from the national and local authorities, with the prevalence of a repressive policy and absence of support. • The gender dimension on scavenging activities; and • The perception of health risks. The findings are that scavenging constitutes a means of livelihood for poor people. These activities respond to the market demand and not to environmental considerations. However, in performing scavenging activities which results in informal recycling and resources recovery, people generate environmental benefits, economic benefits and social benefits. Other findings are that the informal organization of scavengers increases the exploitation and the health risk of scavengers. Thus, organization is a key to the success of scavengers and indirectly to the municipal economy. It is concluded that the framework set out in this thesis is useful in the sense that it illustrates the factors which influence scavenging activities. This framework can be used for further research in similar situations. It is also concluded that prohibition of scavenging activities would have undesirable consequences for the economy of Maputo in particular and of Mozambique in general. Thus, since this activity brings benefits to scavengers and to society, the government should support and stimulate this activity and not persecute those who provide this service. Consequently, as a recommendation, government, local communities and NGOs are called upon to support scavengers. The formation of scavenger co-operatives can promote sustainable grassroots development in this sector of the population. / Thesis (M.Env.Dev.)-Unversity of Natal, Pietermaritzburg, 2001.

The temporal fate of selected parameters, including redox potential; pH; phenol; nitrates; sulphates; copper and zinc, of a young synthetic acetogenic phase landfill leachate was assessed by perfusing a series of sequential soil (Hutton) microcosms (arrays) at two hydraulic loading rates (HLR). We chose HLRs that were representative of areas in South Africa with typically elevated rainfall (Pietermaritzburg – HLRh) and one with relatively low rainfall (Kimberley – HLRl). Preliminary phenol, copper, and zinc adsorption investigations on gamma radiation sterilized soil and unsterilized soil revealed superior adsorption rates for each compound in the unsterilized soil. This revealed the importance of the biological component of soil in phenol, copper, and zinc attenuation in soil. The results presented in this thesis suggest that the HLR of leachate into soil arrays contributes to significant differences in the fate of the landfill leachate parameters mentioned earlier. In addition, we assessed the temporal and spatial succession of bacterial community diversity in each of the soil arrays by polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE). Prior to this, we compared two soil DNA isolation techniques, the modified method of Duarte et al. (1998) (Bead Beat) and the commercial Mo-Bio UltraClean™ Soil DNA isolation kit (Kit). The DNA isolated by the Kit method was significantly superior regarding purity and absence of DNA fragmentation. However, the Bead Beat method produced a significantly higher yield per reaction before further purification with Wizard™ Clean-Up columns produced DNA extracts of similar purity at the cost of a significant reduction in DNA yield. The Kit method was chosen for future DNA isolation and PCR-DGGE based on the quality of the PCR amplicons generated from the Kit isolated DNA. PCR-DGGE was further optimized by comparing the efficiency and sensitivity of a silver stain against ethidium bromide. Silver stain generated DGGE gels with greater number of bands (species richness – S) and stronger band signal intensities. Captured DGGE fingerprints generated data that were subjected to the Shannon-Weaver Index (H’) and the associated Shannon-Weaver Evenness Index (EH) to measure the change in spatial and temporal bacterial diversity. There was a significant shift in S and H’ for both HLRs but a significant change in EH was only observed for HLRh. Furthermore, a temporal comparison of S and H’ between both HLRs revealed significant differences throughout the investigation. Canonical Correspondence Analysis (CCA) revealed spatial distribution of bacterial community diversity with depth. Effects of phenol concentration, redox potential, and pH of the effluent leachate on bacterial community diversity was tentatively assessed by three-dimensional graphical representation on PlotIT 3.2 software. Bacterial community diversity showed a decrease with elevated pH and phenol concentration along with decreasing redox potentials for both HLRs. While this study reveals the spatial and temporal dynamics of bacterial community diversity in situ, it provides important evidence with respect to: (i) the effects of rainfall / leaching rates (HLR) on spatial and temporal bacterial community succession; (ii) the importance of the biological component in natural attenuation; (iii) the ability of soil, previously unexposed to landfill leachate, to initiate natural attenuation of phenol and other leachate constituents; (iv) the capacity of PCRDGGE to fingerprint successional changes in bacterial community diversity, (v) and the potential to clone and sequence selected members of bacterial associations for future reference in environmental remediation strategies. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.