Date of Award
Great Lakes Institute for Environmental Research
Christopher G Weisener
Acid Mine Drainage, Bioreactor, Metals, Microbiology, Reclamation
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This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Acid mine drainage (AMD) remediation commonly produces by products which must be stored or utilized to reduce the risk of further contamination. A mussel shell bioreactor has been implemented at a coal mine in New Zealand, which is an effective remediation option, even though an accumulated sludge layer decreased efficiency. To understand associated risks related to storage or utilizing the AMD sludge material, a laboratory mesocosm study investigated the physio-chemical and biological influences under two conditions: anoxic storage (burial deep within a waste rock dump) and exposure to oxic environments (use of sludge on the surface of the mine). Solid phase characterization by SEM (scanning electron microscope) and selective extraction was completed to compare two environmental conditions (oxic and anoxic) under biologically active and abiotic systems (achieved by gamma irradiation). Changes in microbial community structure were monitored using 16s rDNA amplification and next-generation sequencing. The results indicate that microbes in an oxic environment increase the formation of oxyhydroxides and acidic conditions increase metal mobility. In an oxic and circumneutral environment, the AMD sludge may be repurposed to act as an oxygen barrier for mine tailings or soil amendment. Anoxic conditions would likely promote the biomineralization of sulfide minerals in the AMD sludge by sulfate reducing bacteria (SRB) which were abundant in the system. The anoxic conditions reduced the risk of contaminants from oxides but increased the risk of Fe associated with organic material. In summary, fewer risks are associated with anoxic burial but repurposing in an oxic condition may be appropriate under favorable conditions such as a neutral pH.
Butler, Sara, "Storage Impacts and Biogeochemical Characterization of Acid Mine Drainage Sludge from a Novel Mussel Shell Bioreactor" (2019). Electronic Theses and Dissertations. 7632.