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In-situ microbial dissolution of iron mineral-bearing wastes for metal recovery

Roberts, Mark 2018. In-situ microbial dissolution of iron mineral-bearing wastes for metal recovery. PhD Thesis, Cardiff University.
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This thesis presents an investigation of whether indigenous iron reducing microbial communities in metalliferous ferric oxide-bearing wastes can be stimulated and exploited for the in-situ recovery of metals within these wastes. A range of ferric oxide-bearing wastes including from mining wastes, water treatment sludges and metallurgical wastes were tested. When glycerol was introduced to the wastes, only those originating from a former coal mine and those from a former Cu mine displayed stimulation of indigenous iron-reducing communities. A coeval release of Pb and Fe was observed from the latter of these two wastes, during column tests, but direct metal recoveries via effluent extraction was limited. This was attributed largely to the microbial activity causing the pH to increase towards circum-neutral resulting in a decrease in metal solubility. A substantial redistribution of metals of interest between mineral phases of the waste was observed. This resulted in significant increases in the recovery of these metals when the wastes were leached with dilute acid and highlights the potential use of bioreduction as an effective pre-treatment of these wastes. The stimulated indigenous microbial communities within the wastes were also characterised. It was found that the introduction of glycerol caused a decrease in the community diversity with members of the Firmicutes phyla typically dominating the post-experiment waste. The most abundant genus identified was Desulfosporosinus, which is known to be capable of adapting to changing conditions by switching between iron and sulphur reduction as necessary and may be doing so within the column tests. Desulfosporosinus spp. also proved capable of surviving the autoclaving process. These characteristics demonstrate that this genus is very hardy and potentially exploitable for ex-situ extraction methods.

Item Type: Thesis (PhD)
Date Type: Submission
Status: Unpublished
Schools: Engineering
Uncontrolled Keywords: In-Situ; Resource recovery; Dissimilatory iron reducing microbes; Iron bioreduction; Indigenous communities; Mine wastes.
Date of First Compliant Deposit: 26 September 2018
Last Modified: 30 Mar 2021 10:49

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