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Concepts and Strategies |
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University of Padua IMAGE Department |
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Long term landfill impact |
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Landfill sustainability |
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The current technology of landfilling causes anaerobic degradation processes to develop and persist in the waste mass, producing polluted leachate and biogs for a very long time. Liners might leak and drainage systems clog and this in addition to the traditional impacts, such as the occurence of odours, which invariably render landfill siting and public acceptance a problem. Accordingly, the sustainability of a landfill, whereby no environmental problems should be left to future generations, represents the main goal to be achieved by modern landfill strategies. In order to reduce the emission potential of existing landfills two main activities can be thought of: • controlled water infiltration f.e. by using treated leachate • in situ aeration For existing and new landfills, mechanical biological pre-treatment is a prerequisite measure in order to operate a sustainable landfill. |
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Multibarrier concept |
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A landfill has to be designed by combining several different barriers, intending for barrier all the measures suitable to reduce the release of emissions to the environment. No landfill should rely only on one barrier. The landfill safety should be evaluated on the overall bahaviour with time of the combination of the different barriers. |
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Scheme of a multibarrier landfill |
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Pretreatment and operation measures for a sustainable landfill |
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(R. Stegmann, 2003) |
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Criteria for emission control |
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A. Mechanical Biological Pretreatment |
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The pretreatment of waste with mechanical-biological or thermal processes allows to reduce the waste potential environmental impact before the landfilling. |
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B. Aeration |
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The in situ aeration of landfill with forced aeration (aerobic landfill) or natural convection aeration (semiaerobic landfill) allows to convert the anaerobic processes in aerobic waste degradation |
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C. Flushing |
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The in situ and off site flushing of waste enables the solubilization of substances and consequently their transport in liquid form. |
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The PAF model |
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Structure of a PAF landfill |
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The aerobic in situ stabilization accelerates biological degradation processes in the landfill body so that after a treatment time of approx. 2-4-years the emissions are, compared to anaerobic conditions, significantly reduced. This is due to the reduction of organic components that are easier degradable under aerobic than anaerobic conditions. This is also relevant for many hazardous waste components which enter the landfill with the MSW and/or commercial waste. |
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Recirculatory semi-aerobic landfill, using concrete pipe, bamboo and used steel drums (Y. Matsufuji, 2003) |