Abstract:
The formation of environmentally toxic acidic waste from mining activities is a world-wide
problem. Neutralization of this waste can be accomplished by physicochemical and/or
biological means. In this short-term study, synthetic acid mine drainage was added to sandfilled
mesocosms containing silica-dominated (quartz) sand. Glucose was added as a carbon
source for microbial iron and/or sulphate reduction. Replicates contained two separate
batches of sand obtained from the same quarry site. The investigations used to assess and
compare the chemical and biological functioning of the replicates included system hydraulic
conductivity measurements, sand chemistry, effluent chemistry and bacterial community
fingerprinting. Minor differences in composition of the sand, including the levels of available
nutrients and micronutrients, resulted in major differences in measured parameters. Significant differences in effluent chemistry were found in systems containing different
batches of sand. It was demonstrated that the characteristics of the sand and the presence
of acid mine drainage impacted the bacterial community structure and function. The
importance of the physical substrate on the selection of functional microbial communities in
systems remediating AMD should not be under-estimated. The physical substrate should be
carefully selected and it may be prudent to include small-scale comparative studies in each
particular setting prior to full-scale implementation.
