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Present day society generates large volumes of waste that present an environmental hazard when disposed of in landfills. As our population grows, so does the volume of waste generated and hence the threat to our environment. One method of reducing harmful emissions in landfills is the mechanical-biological pretreatment of waste prior to landfilling. The purpose of this dissertation is to investigate the degree of stabilization of waste in shallow landfills (simulated by test cells) with particular focus on biogas production and quality. Municipal waste was composted in aerobic, open windrows for periods of eight and sixteen weeks. Five test cells, designed and operated according to the PAF model (Pretreatment, Aeration and Flushing) were constructed at the Bisasar Road landfill site. These cells were used to simulate large scale municipal landfill sites. They were filled with fresh and pretreated waste and were used to monitor the dynamics of prolonged aeration and degradation of waste over a period of six months. The cells were monitored on a weekly basis while being aerated. Two flushing events were conducted at the beginning of the passive aeration. Gas emissions were also monitored by recording the methane, carbon dioxide and oxygen volumes per volume of air in probes strategically placed in each cell. These results were then analysed to assess the effect of mechanical-biological pretreatment of municipal solid waste on the emission quality of sanitary landfills and the appropriateness of prolonging the aeration in shallow landfills, as often used in sub-tropical countries. It was found that the design of the test cells was appropriate for the landfilling and stabilization of waste that was aerobically treated. After six months in the test cells, analysis of the waste from each cell showed that the waste was completely degraded. The PAF model, when applied to shallow landfills, is very effective in stabilising waste and would be appropriate for a sub-tropical climate. Waste that is pretreated, placed in shallow landfills, initially flushed and then aerated over a six month period was fully stabilized. The requirement for such treatment would be relatively small amounts of waste, a wet climate and the availability of open space for shallow landfills. This method, therefore, would be very appropriate in a South African context. The major problem with this method may be the generation of large quantities of leachate which will have to be treated and disposed of in an environmentally safe manner. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2006.

This research was carried out at the Bisasar Road Landfill site, Durban, South Africa, / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2007.

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Loss of biodiversity has been in the forefront of conservation issues worldwide since the last century. Biodiversity conservation through restoring degraded habitats or creating new habitats is advocated in the UK Biodiversity Action Plan. Newly created grasslands on restored landfill sites are semi-natural habitats that could support a number of species. However, it is unknown whether these re-created habitats represent a significant resource in terms of biodiversity conservation though poor quality soil was being used for restoration. A multi-taxon approach was applied to examine the biodiversity potential of these novel habitats. Plants (vascular plants and bryophytes), invertebrates (carabid beetles and land snails), and vertebrates (birds) were studied on nine restored landfill sites and paired reference sites in the East Midlands region of the UK during 2007 and 2008. Plant species data were collected by random quadrats along two 100m transects from each site; carabid beetles were censused by pitfall traps; land snails were investigated by hand searches along the transects; and bird species were assessed using point counts. Effects of restoration were investigated by examining species richness, diversity or abundance of studied taxa and also how habitat quality and landscape factors determined species composition on restored landfill sites. A total of 170 plant species (162 vascular plants and 8 bryophytes), 37 carabid beetle, 17 land snail and 12 bird species were found in the studied sites. Species richness and diversity or abundance of studied taxa on restored landfill sites were found to be equal to or above that of reference sites. Compositional differences were found between taxa on restored landfill sites and their corresponding reference sites. Though vegetation composition including NVC plant communities on restored landfill sites was rather homogeneous compared to reference sites, restored landfill sites were found to support a number of nationally decreasing native plant species and of common species of other taxa and also a number of Red List bird species such as Skylark (Alauda arvensis), Grey partridge (Perdix perdix), Lapwing (Vanellus vanellus), Tree sparrow (Passer montanus) and Starling (Sturnus vulgaris). Habitat quality and landscape variables were found to be significant predictors for different species. Underlying soils were found to be an important factor in determining the heterogeneity of the plant communities within the study area which in turn dictates suitability of habitat for other taxonomic groups. A lack of congruency between taxa supports the incorporation of a multi-taxa approach into restoration plans. Management in terms of cutting or mowing of these landfill sites were found to have varying influences on different taxa. Moreover, restored landfill sites had less disturbance than reference sites as there was restricted access to dog walkers and for recreational purposes. This may be one of the main factors that could enhance the richness and abundance of a number of taxa, especially bird species. Management of these landfill sites should be targeted on species-specific goals as these sites can play a significant role in Local Biodiversity Action Plans. Overall, this study indicates that restored landfill sites have potential biodiversity conservation value in a complex modified human landscape.