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Title:
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Prediction of the long-term leaching behaviour of a sustainable landfill containing predominantly inorganic waste
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Author(s):
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Published by:
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Publication date:
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ECN
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1-10-2005
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ECN report number:
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Document type:
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ECN-RX--05-166
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Conference Paper
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Number of pages:
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Full text:
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15
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Download PDF
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Presented at: Sardinia 2005, Tenth International waste management and landfill symposium, Sardinia, Italy, 3-7 oktober 2005.
Abstract:
The predominantly inorganic waste landfill
concept is part of a larger project on sustainable landfill concepts
in the Netherlands. The project is aimed at creating biogeochemical
equilibrium between a landfill and the environment within a period of
30 years, in order to reduce the long-term risk and the aftercare needs.
It has already been reported that there is in general a very good agreement
between the leaching behaviour of the constituted waste mix (analysed
on laboratory and lysimeter scale) and the leachate as obtained from
the full-scale pilot demonstration cell. However, deviations in the
leaching behaviour of Cu, Fe and Mn have been found between experiments
on laboratory-, lysimeter- and pilot scale. The different
redox potentials lead to relatively large deviations in the emissions
of Cu, Fe and Mn on the different test scales. It is found that the
cumulative release of Cu is much lower in the pilot experiment compared
to the other test types (lysimeter and column leaching tests) due to
a low redox potential under field situations. Cu(II) is reduced to Cu(I).
Moreover, the affinity of humic substances for metal complexation is
possibly much lower for Cu(I) species and the formation of relatively
insoluble copper sulphides may be a dominant process. Fe and Mn show
a relatively high leaching in the pilot experiments, which is in line
with the laboratory column test results but much higher than the lysimeter
experiments. Fe is normally present as Fe(III) and can easily be reduced
to more soluble Fe(II) species in a reducing environment. The leaching
of Mn in the pilot experiments and the column experiments is higher
than the results for the lysimeters. Under reducing conditions like
in the pilot experiment and (to a lesser extent) the column test, the
soluble Mn(II) species will be dominant. This species can easily be
oxidised to Mn(IV) which forms solid oxides. Geochemical release modelling
on column leaching test data showed that the model generally predicts the release of Cu, K, Pb and SO4-2
very well. This implies that the chemical processes leading to release
are understood. The results indicate that preferential flow aspects
are important for the long-term prediction of the release of mobile
elements from a landfill. The model predicts the release quite well.
This modeling approach is comprehensive in that it deals with all major,
minor and trace elements simultaneously and partitioned between dissolved
(free and DOC bound) and solid phases (minerals, Fe-oxide, Al-oxide
and particulate organic matter).
However, a few contaminants show deviations in concentration
of over one order of magnitude and these deviations need to be sorted
out in future work.
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