Selective removal of transition metals from acidic mine waters by novel consortia of acidophilic sulfidogenic bacteria.
Bottom Line: Two continuous-flow bench-scale bioreactor systems populated by mixed communities of acidophilic sulfate-reducing bacteria were constructed and tested for their abilities to promote the selective precipitation of transition metals (as sulfides) present in synthetic mine waters, using glycerol as electron donor.Analysis of the microbial populations in the bioreactors showed that they changed with varying operational parameters, and novel acidophilic bacteria (including one sulfidogen) were isolated from the bioreactors.The modular units are versatile and robust, and involve minimum engineering complexity.
Affiliation: School of Biological Sciences, Bangor University, Bangor LL57 2UW, UK.Show MeSH
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Mentions: Bioreactor I was subsequently operated (for 56 days) with a feed liquor similar in composition to water draining the abandoned Mynydd Parys copper mine, with the bioreactor pH maintained at 2.6. All of the copper, but none of the ferrous iron, aluminium or manganese, were precipitated within the bioreactor under these conditions (Fig. 3). As before, some precipitation of zinc (sulfide) occurred (∼75% of that in the influent) at pH 2.6 when the glycerol concentration in the feed liquor was 3 mM. Decreasing the glycerol concentration to 0.7 mM lowered the amount of zinc precipitated to about 30% of that in the synthetic mine water, and this was depressed further (to ∼25%) when the yeast extract content of the influent was lowered from 0.01% to 0.005%. Numbers of bacteria in the upper liquid phase of the bioreactor decreased significantly as a result of lowering the concentrations of both glycerol and yeast extract (Fig. 3). Concentrations of acetic acid corresponded to a mean of ∼9.5% of the glycerol that was oxidized during this phase of operation.
Affiliation: School of Biological Sciences, Bangor University, Bangor LL57 2UW, UK.