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Phytoremediation of landfill leachate: a clean transition from laboratory to green environment

ricerca percolato piante

Industrial and commercial growth in many countries around the world in the past decades has been accompanied by increases in municipal and industrial solid waste production. Nowadays disposal of waste to landfill remains the most common method of waste management around the world, with up to 95% of generated refuse placed in landfill, because it is simple and relatively inexpensive (Kim and Owens, 2010). Nevertheless, there are pollution concerns since landfilled waste is comprised of a wide range of inorganic, natural and xenobiotic compounds, the mixture of which in turn affects the composition and polluting potential of the leachate (Kjeldsen et al., 2002). The latter, is the liquid that moves through or drains from landfill and it is generated by excess rainwater percolation through waste or inherent water content of waste. It represents a critical issue not only for its toxic impact on the environment, especially pollution of groundwater and surface water, but also because it can persist for many years after landfill closure. The release is normally a potentially highly polluted chemical cocktail containing large amount of organic matter as well as ammonia-nitrogen, heavy metals, chlorinated organics and inorganic salts (Renou et al., 2008). During initial acetogenic biodegradation step leachate is characterized by a high chemical oxygen demand (COD), biological oxygen demand (BOD), and Na, Cl and NH4+ content (Andreottola and Cannes, 1992), it is extremely toxic to life and dangerous to the environment. In the subsequent methanogenic step leachate presents a relatively lower COD, BOD and NH4+ content with a decrease toxicity. In addition, leachate composition varies greatly among landfills depending on waste composition, waste age and landfilling technology (Kjeldsen et al., 2002). In all instances, leachate treatment is mandatory since regulations in many countries have required the installation of leachate collection systems as well as plan for leachate treatment.