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End of landfill aftercare |
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University of Padua IMAGE Department |
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The aftercare may end, when the emission potential is that low, that the actual emissions do not harm the environment. This means, that leachate treatment should not be practiced anymore and that the landfill gas is naturally oxidised in the top cover of the landfill. The emission potential of landfills can be described by means of waste samples taken from the specific landfill areas which may be analysed regarding their biological activity (respiration test), elution potential (elution test) as well as their actual and future landfilling behaviour (landfill lysimeter test). Release of a landfill out of the aftercare period should mean that the landfill can be left without any operation and/or supervision due to an environmental accettable emissio potential and actual emissions. In this context it should be discussed if this is realistic, since there are f.e. leachate pumping from pit landfills, cleanining of drainage pipes, care of the vegetation, natural post treatment of leachate on the landfill site, control of sewage pipes, manholes as well as groundwater monitoring. In-situ aeration of old landfills In-situ aeration has become one of the most promising options for old MSW landfill remediation. The design of full scale in-situ aeration plants requires the evaluation of parameters such as well radius of influence, air pressure gradient in the landfill and optimal air flow rate. These can be calculated only if preliminary field-tests are made and the characteristics of the deposited waste are known. The aeration of landfills is obtained by means of forced low pressure air injection/extraction within the waste mass: as a consequence the aerobic conversion of the biodegradable organic substance is enabled. |
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Forced aeration:“Airflow” technology |
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Airflow installation in a Noth Italy landfill: Biofilter |
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Airflow installation in a Noth Italy landfill: Pipelines |
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Airflow installation in a Noth Italy landfill: Air pumping |
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Landfill mining |
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Landfill mining consists in the waste extraction from the landfill body and waste treatment. With this technique , the following main advantages can be achieved: • Material recovery: it is possible to recycle some materials, which, otherwise, would represent a potential source of pollution for the environment, especially for old landfills wuthout containment liners • Volume recovery: the possibility to recover a large fraction of the excavated waste leads to a longer life time for operating landfills or to the availability of new a new site in the case of closed landfills • Landfill reclamation: the removal of the waste and the stabilisation of hazardous fractions represent a sefety solution against their pollution potential |
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(R. Stegmann, 2004) |
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Subsequent base sealing |
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(R. Stegmann, 2004) |
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Experience of landfill mining |
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• From the economical point of view, old landfill reclamation is convenient when more aims are simultaneously pursued • Energy recovery fron excavated waste is not enough to reach economical convenience • It can be achieved, instead, if also volume recovery and/or site reclamation is carried out • For waste selection and treatment, conventional techniques are available (sieving, magnetic separation, balistic separation, air classification, etc.), but particular aspects must be also taken under consideration, like, for example, gaseous emissions during excavation. |
