Field-Scale AMD Remediation: Microbial Community Dynamics and Functional Insights in Biochemical Passive Reactors

Area of Science:

• Environmental Microbiology
• Bioremediation
• Mining Engineering

Background:

• Acid mine drainage (AMD) from coal mining poses significant environmental risks due to low pH, high metal/metalloid concentrations, and elevated sulfates.
• Biochemical passive reactor (BPR) systems show promise for in-situ AMD bioremediation, but their performance at field-pilot scale requires validation.
• Previous lab-scale studies identified specific microbial communities, including (ligno)cellulolytic organisms and sulfate-reducing bacteria (SRB), as crucial for AMD treatment in BPRs.

Purpose of the Study:

• To investigate the taxonomic and functional diversity of microbial communities in field-pilot scale BPRs treating AMD.
• To determine if the microbial composition observed in lab-scale BPRs is maintained under environmental conditions at a larger scale.
• To assess the bioremediation effectiveness and underlying microbial dynamics in scaled-up BPR systems.

Main Methods:

• 16S rRNA gene metabarcoding analysis to characterize microbial taxonomic diversity.
• Shotgun metagenomics analysis to assess functional gene potential and community structure.
• Application of these molecular techniques to microbial communities within a multi-unit field-pilot BPR system.

Main Results:

• Bioremediation effectiveness in the field-pilot BPRs was driven by syntrophic interactions among hydrolytic, fermentative, and sulfate-reducing bacteria.
• These functional dynamics align with observations from previous laboratory-scale BPR studies.
• While specific microbial taxa composition varied, the core operational microbial processes essential for AMD treatment remained preserved at the field-pilot scale.

Conclusions:

• The study confirms that scaled-up BPR systems can maintain the essential microbial consortia and functional dynamics required for effective acid mine drainage bioremediation.
• Syntrophic interactions among key bacterial groups are critical for AMD treatment, regardless of scale.
• BPR technology represents a robust and viable approach for in-situ remediation of AMD under real-world environmental conditions.