Čerpání a využití bioplynu ze skládky Adelaide v Austrálii
Recovery and Use of Landfill Gas in Adelaide, South Australia
Treloar, J. 1998
Australians rate amongst the highest producers of waste in the world, producing an average of 780 kilograms of disposable solid waste per capita annually (NOGIC 1996). The accumulation of waste, deposited mainly in landfill sites, creates large amounts of landfill gas that becomes an environmental pollutant and a re-useable energy source.
The main constituents of landfill gas are methane and carbon dioxide, both of which are major contributors to global warming. Methane is also a highly flammable gas, making it a also a threat to public safety. This report looks at the potential impact on the biosphere and atmosphere resulting from landfill gas as a pollutant, and also discusses the risks to public health and safety. Some practical methods of minimising environmental degradation, and using landfill gas as a valuable commercial resource in terms of current usage and future potential are also discussed.
Landfill sites remain the most common means of waste disposal in the Adelaide metropolitan area. Unless properly planned and managed, landfill sites threaten to become a significant source of environmental degradation and air pollution. Gases generated by microbiological breakdown of organic waste material can create an environmental liability, but paradoxically the major component gas, methane, can be used as a non-polluting fuel source.
The aim of this report is to consider the following aspects of landfill gas:
· Source and analysis of landfill;
· Location and description of sites within the Adelaide metropolitan area;
· Implications for public health and safety;
· Effects of soil contamination and biotic degradation, air pollution and Greenhouse gas emission;
· Waste management practices for landfill gas extraction and control;
· Applications for methane as an economically viable energy source;
· Waste management alternatives for the future.
The emission of landfill gas from waste provides an opportunity to convert a potential liability into an economic asset whilst reducing environmental degradation. The solutions are technically feasible, requiring incentives enforced by a regulatory framework to provide the impetus for further exploitation of this resource.
Source and analysis of landfill Gas
The main components of landfill gas are by-products of the decomposition of organic material, usually in the form of domestic waste, by the action of naturally occurring bacteria under anaerobic conditions. A typical landfill gas analysis is shown in Table 1.
Methane and carbon dioxide production typically rises to peak within 6 to 12 months of the site closure, then gradually declines over a 30 to 50 year period. The rate of gas production is influenced by the interaction of several environmental factors. These factors determine the decomposition rate which, in turn, affects the volatility and productive life of a site. Figure 1 illustrates the interaction of the factors that influence the gas production process.
Table 1: Typical analysis of raw landfill gas.
Methane (CH4) 40-60%
Carbon Dioxide (CO2) 20-40%
Nitrogen N2) 2-20%
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