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Open AccessArticle

Biogeochemical Characterization of Metal Behavior from Novel Mussel Shell Bioreactor Sludge Residues

1
Great Lakes Institute for Environmental Research (GLIER), University of Windsor, Windsor, ON N9B 3P4, Canada
2
CRL Energy Ltd., Christchurch 8024, New Zealand
*
Author to whom correspondence should be addressed.
Geosciences 2019, 9(1), 50; https://doi.org/10.3390/geosciences9010050
Received: 6 December 2018 / Revised: 3 January 2019 / Accepted: 9 January 2019 / Published: 18 January 2019
(This article belongs to the Special Issue Microbial Biomineralization)
Acid mine drainage (AMD) remediation commonly produces byproducts 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, although an accumulated sludge layer decreased efficiency which was then removed and requires storage. To understand associated risks related to storage or use of the AMD sludge material, a laboratory mesocosm study investigated the physio-chemical and biological influence in two conditions: anoxic storage (burial deep within a waste rock dump) or exposure to oxic environments (use of sludge on the surface of the mine). Solid phase characterization by Scanning Electron Microscopy (SEM) 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 trace metals (Zn) associated with oxides, but increased 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. View Full-Text
Keywords: acid mine drainage; bioremediation; microbiology; mussel shells; mesocosm; contaminate waste storage acid mine drainage; bioremediation; microbiology; mussel shells; mesocosm; contaminate waste storage
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MDPI and ACS Style

Butler, S.C.; Pope, J.; Chaganti, S.R.; Heath, D.D.; Weisener, C.G. Biogeochemical Characterization of Metal Behavior from Novel Mussel Shell Bioreactor Sludge Residues. Geosciences 2019, 9, 50.

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