Questão 23

(IME - 2016/2017 - 2ª FASE)

Texto 1

LANDFILLS AND THE INTRODUCTION OF NANOMATERIALS IN WASTE

Waste disposal on land (dumping) and landfilling remain the most prominent waste management techniques used ___(16)___. The standards and practices for this type of waste disposal vary greatly ranging from uncontrolled sites to highly specialised and controlled engineered landfills. The potential ___(17)___ of contaminants through landfill gas and leachate is largely dependent on landfill design, site conditions and the sophistication of the control measures in place, ___(18)___ landfill gas recovery and leachate collection and treatment systems.

Modern engineered landfills use ___(19)___ barriers, with few relying on natural barriers, to line the bottom of a landfill and incorporate collection systems for both leachate and landfill gas. The purpose of these collection systems is to capture and treat leachate and landfill gas; __(20)____ preventing the migration of leachate into ground/surface water and the release of untreated landfill gases to the atmosphere. An un-engineered landfill would be considered an uncontrolled system due to the lack of environmental controls, potentially resulting in significant environmental exposure of contaminants.

Because of widespread use of ENMs in a broad range of products, it is possible that some ENMs ___(21)___ through landfill gases; however this report will primarily focus on ENMs that may be present in landfill leachate, as this is considered to be the primary means by which ENMs could be transported___(22)___ a landfill. Characterisation of landfill gases to identify the presence of ENMs __(23)____ an important area for further research. Landfill leachate is generated when rain passes through the waste mass and by the liquid generated due to the breakdown of waste ___(24)___ the landfill. The composition of leachate is extremely ___(25)___ depending on the type of waste landfilled, the quantity of precipitation, the construction and operation of the landfill, the age of the landfill and other factors such as pH, temperature and microbial populations. (…)
ENMs = engineered nanomaterials.

Organisation for Economic Co-operation and Development. Landfills and the introduction of nanomaterials in waste. In: Landfilling of waste containing nanomaterials and nanowaste, 2015. Disponível em: <http://www.oecd.org/officialdocuments/ publicdisplaydocumentpdf/? cote=ENV/EPOC/WPRPW(2014)5/FINAL&docLanguage=En>. Acesso em: 22/04/2015.

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