Microbiology and Geochemistry of Mine Tailings Amended with Organic Carbon for Passive Treatment of Pore Water

Abstract

A field-scale experiment was conducted to evaluate organic carbon amendment of mine tailings as a technique for pore water and drainage treatment. Six test cells were constructed by amending sulfide-and carbonate-rich tailings with varied mixtures of peat, spent-brewing grain and municipal biosolids. Samples were collected for microbial, geochemical and mineralogical analysis approximately three years after commencing this experiment. Test cells amended with spent-brewing grain promoted sulfate reduction and effective removal of sulfate and metal(loid)s. The addition of municipal biosolids did not sustain enhanced sulfidogenesis after three years, and peat was an ineffective source of organic carbon. Terminal-restriction fragment length polymorphism revealed that test cells which supported sulfidogenesis exhibited the greatest microbial diversity. Indigenous bacteria identified using molecular and cultivation analyses were found to be related to Cellulomonas, Thiobacillus, Bacteroides, Paludibacter and Desulfovibrio, which was the only sulfate-reducing bacterial (SRB) isolated. The results demonstrate that mixtures of solid organic materials which supported complex anaerobic microbial communities, including sulfate-reducing bacteria, were most effective in promoting porewater treatment.

Strategizing Carbon-Neutral Mines: A Case for Pilot Projects

“…For example, Mitchell et al [91] suggest that municipal wastewater (~20 g urea/L) could be injected into the subsurface where bacterial ureolysis would generate alkalinity thereby inducing Ca-carbonate precipitation and fixing CO 2 . Lindsay et al [92,93] proposed amending mine tailings with waste organics for preventing the release of toxic metals through enhancing in situ microbial sulfate reduction. Use of peat, spent brewing grain, and municipal biosolids generated alkalinities of ~1000-2000 mg CaCO 3 /L with δ 13 C values (<-20‰) indicating that dissolved inorganic carbon (DIC) was supplied by oxidation of organics [92,93].…”

“…Lindsay et al [92,93] proposed amending mine tailings with waste organics for preventing the release of toxic metals through enhancing in situ microbial sulfate reduction. Use of peat, spent brewing grain, and municipal biosolids generated alkalinities of ~1000-2000 mg CaCO 3 /L with δ 13 C values (<-20‰) indicating that dissolved inorganic carbon (DIC) was supplied by oxidation of organics [92,93]. Biosolids may also be used for stabilizing and revegetating mine tailings [94][95][96].…”

Novel Molecular Tools to Assess Microbial Activity in Contaminated Environments

“…Other studies used those fingerprinting techniques when monitoring the effects of different remediation techniques such as amending mine tailings with a mixture of organic carbon sources to treat pore water and drainage (Lindsay et al 2011), incorporating compost into a heavy metal-contaminated acidic soil (Farrell et al 2010), or testing the effects of phytoremediation approaches (MartinezInigo et al 2009;Tipayno et al 2012) or landfarming on oil refinery sludge (Ros et al 2010). …”

Long-term mineralogical and geochemical evolution of sulfide mine tailings under a shallow water cover

“…Media were filter sterilized and 9 mL aliquots were dispensed into sterile culture tubes. As described by Lindsay et al (2011), APB were grown in a saccharide and peptide medium (Hulshof et al, 2003), whereas IRB and SRB were grown in Fe(III) EDTA and modified Postgate C (Blowes et al, 1996) media, respectively. Culture tubes were filled with 9 mL aliquots of the APB medium, capped, and sterilized.…”