nÃo hà / O crescente consumo humano acarreta uma maior geraÃÃo de resÃduos, que, por sua vez, devem ser adequadamente tratados e descartados. O armazenamento dos resÃduos urbanos em aterros produz gases, que quando nÃo geridos corretamente prejudicam a qualidade de vida da populaÃÃo. As emissÃes incontroladas desses gases provocam mÃltiplos impactos econÃmicos e socioambientais a partir da contaminaÃÃo do ar nas diferentes cidades do mundo. A comunidade circunvizinha do aterro à bastante prejudicada em virtude do convÃvio constante com o mau cheiro, gases inflamÃveis e atà componentes cancerÃgenos presentes no biogÃs. Em termos mundiais, o lanÃamento incontrolado do biogÃs na atmosfera à uma das contribuiÃÃes humanas para o aumento dos Gases causadores do Efeito Estufa (GEE) e aquecimento global. Uma das principais formas de se evitar a passagem aleatÃria do biogÃs gerado em aterros para a atmosfera à constituir um adequado sistema de cobertura dos resÃduos, a qual tem, dentre outras funÃÃes, evitar a fuga dos gases e a entrada de Ãguas pluviais na massa de resÃduos, alÃm de auxiliar na coleta e tratamento do biogÃs gerado no interior do aterro. Desenvolveu-se tÃcnicas de laboratÃrio e em campo para contemplar o estudo do fluxo de gases que atravessa o solo utilizado como cobertura do Aterro SanitÃrio Metropolitano Oeste de Caucaia (ASMOC), com o objetivo de se avaliar a funcionalidade da camada de cobertura e se estimar a quantidade de gases, metano (CH4) e diÃxido de carbono (CO2), emitidos pelo Aterro. Escolheram-se quatro pontos distintos na superfÃcie da cÃlula, onde foram coletadas duas amostras, uma deformada e outra indeformada, para cada ponto selecionado. Os resultados mostraram que o solo da camada de cobertura foi classificado como areia fina silto-argilosa, com permeabilidade de 2,2 x 10-4 cm/s, limite de liquidez de 27%, limite de plasticidade de 14% (Ãndice de plasticidade: 13%), massa especifica seca mÃxima de 1,83 g/cm e umidade Ãtima de 11%. Utilizou-se a metodologia de mediÃÃo por placa de fluxo de alta sensibilidade, onde se mediu o fluxo que atravessa a camada de cobertura, utilizando-se aparelhos de precisÃo. A mÃdia do fluxo de CH4 emitido pela camada de cobertura variou entre 105 e 1.361 m3/dia.m2, enquanto a mÃdia dos fluxos de CO2 variou de 76 à 1.048 m3/dia.m2. O fluxo mÃdio de CH4 pode atingir valores prÃximos de 9.452 t/ano, o que representa aproximadamente 198,5 mil t de CO2eq por ano em uma Ãrea de 78 hectares do aterro / The growing human consumption entails a greater generation of waste, which, in turn, must be properly treated and disposed. The storage of waste in landfills produces gas, which if not managed properly will affect the quality of life. The uncontrolled emissions of these gases cause multiple economic, social and environmental impacts, as due to air pollution in different cities around the world. The community surrounding the landfill is actually impaired by virtue of living with the constant stench, flammable and even carcinogenic compounds present in the biogas. Worldwide, the uncontrolled release of biogas into the atmosphere is one of the human contributions to the increase of greenhouse gases (GHG) emissions and global warming. One of the main ways to avoid the random passage of the biogas generated in landfills to the atmosphere is to provide an adequate coverage of the waste system, which has, among other functions, prevent the escape of gases and the ingress of rainwater into the mass of waste as well as assist in the collection and treatment of the biogas generated within the landfill. Techniques were developed in the laboratory and field research to consider the flow of gases through the soil used as cover Landfill Metropolitan West Caucaia (ASMOC), to assess the functionality of the cover layer and estimate the amount of gases, methane (CH4) and carbon dioxide (CO2) emitted by the landfill. Four different points on the cell surface were chosen, where two samples were collected, a deformed and other undeformed, for each selected point. The results showed that the covering layer is classified as sandy silt-clay, with permeability of 2,2 x 10-4 cm/s, liquid limit of 27%, plastic limit of 14% (plasticity index: 13%), maximum dry density of 1.83 g/cm and optimum moisture content of 11%. The methodology used was the static flow measurement with high sensitivity, which measures the gas flow through the cover layer, using precision instruments. The average flow of CH4 emitted by the layer of coverage ranged between 105 and 1.361 m3/dia.m2, while the average CO2 fluxes ranged 76 - 1.048 m3/dia.m2. The average CH4 flux can reach values close to 9,452 tons / year, which represents about 198 500 tonnes of CO2 eq per year in an area of 78 hectares of the landfill.

This study investigated the establishment of vegetation cover planted in plug and seedling form in the closure phases of the Umlazi Landfill. It also investigated the various facets of the closure process of the Umlazi Landfill and the effect these have on the establishment and choice of vegetative cover, and the grass technology used to make the establishment of vegetation a success. The setting up of trials and the gathering of basic data were undertaken to assess the alternative vegetation options available to researchers. The cover provided by the grasses was assessed in the investigation. The capping of landfill sites is a relatively new approach and it is soon to become a mandatory requirement by the Department of Water Affairs and Forestry (Minimum Requirements for Waste Disposal) (DWAF, 1998). This systematic investigation used in the closure of the Umlazi Landfill, will provide a model for the capping of landfills in South Africa. Seeing that this was the first hazardous (H:h) landfill site in the country to be closed according to the Minimum Requirements for Waste Disposal (DWAF, 1998), every attempt was made to ensure that all aspects in the closure of the site met with the Minimum Requirements. The Minimum Requirements document mentions only briefly that the landfill must be vegetated with some grass type. Prior to 1994, capped landfill sites were usually planted with traditional grass seed mixes and these were not widely successful, as seen on many older landfills that have been partially or completely capped, and where vegetation cover is sparse. There is much literature in the developed countries on the closure of landfills (e.g., Erickson, During the site inspections in June 2001 and February 2002, it was noted that many species of alien plants had established themselves in the poor soil conditions. This made it even more important to find indigenous vegetation to vigorously establish itself that would prevent the establishment of alien invaders. Samples of grass species established on some part of the site were also taken for identification. The dominant grass was identified as Cynodon dactylon. In view of establishing a balanced vegetative cover on top of the Umlazi Landfill, Acacia karoo trees (in seedling form) were also planted. Three bunch grass species, Melinis nerviglumis, Melinis minutiflora and Hyparrhenia hirta, were tested to see if thatching grass could be grown on the site to generate a cash crop for local residents of Umlazi township. Preparation and planting of the capped areas took place in the latter part of 2003 and were completed in early 2004. Measurements and field data were recorded and statistically analysed. The trials revealed three key findings: Firstly, both creeping grasses studied, namely Cynodon dactylon var. “Sea Green” and Panicum natalense var. ”Natal Buffalo Grass” grew well on the site. Initially P. natalense grew faster but after a month, C. dactylon overtook it. At the end of the trial (six months, P. natalense provided a higher level of soil cover. However, C. dactylon grew more consistently over this period. Hence both species provided good growth and cover on this site. Secondly the three bunch grasses, Melinis nerviglumis, Melinis minutiflora and Hyparrhenia hirta, all grew well and had similar survival rates. Hence the potential for growing these grasses as a cash crop has potential. Thirdly, all the Acacia karoo trees survived, i.e., they achieved 100% survival. The average height increase and stem width was similar in all trials and growth was consistent over the six month growing period. Hence the tree species would be a good choice for planting on landfills in its ecologically suitable zones. It is therefore feasible to envisage the planting of a mixture of grasses under the cover of A. karoo trees, to provide a balanced mixture of indigenous grasses to cover a freshly capped landfill. Such a system should provide for stable growth of vegetation for many years. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008