ABSTRACT: The ability of simulated fruit and vegetable waste leachate of different ages to extract lead (Pb)
from mine tailings was investigated. Leachate was produced from two column reactors containing fruit and
vegetable waste. The results showed a high extraction ability (60 – 70%), but with some fluctuations in levels,
for leachates produced during the first 50 days, with a pH of lower than 5.0, while the leachate produced during
days 364 to 434, (pH 6 - 8), showed no ability to extract Pb. These periods were the initial phase and
acidogenesis phase, respectively. When suitable conditions occurred, the degradation process changed to a
methanogenesis phase, where some Pb extraction abilities were observed, but at a much lower degree (<10%)
than the initial-phase leachate. However, methanogenesis and associated humic substance (HS) production did
not go to completion in these ferments, and so remain uncharacterized for Pb extraction ability. The high
dissolved organic carbon (DOC) level and especially the low pH in the leachate likely affected the Pb extraction
ability. As expected, EDTA showed a very high extraction ability, ranging from 61 to 75% of the total available
Pb in the tailings, which was higher than most (but not all) of the simulated leachate abilities.
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