Acid Mine Water Treatment Using Novei Acidophilic Iron-Oxidizing Bacteria of the Genus 'Ferrovum': Effect of Oxygen and Carbon Dioxide on Survival

摘要

Acid mine waters are characterized by low pH and high loads of iron and sulfate, resulting from the oxidative dissolution of sulfide minerals due to the mining activities. Owing to the effect of these contaminations on the environment, mine waters have to be treated before discharging into the rivers. At the open-cast pit Nochten (Germany) acid mine waters were remediated biotechnologically in a pilot plant by immobilization of ferrous iron resulting from microbial iron oxidation with subsequent precipitation of the iron-oxyhydroxysulfate schwertmannite. The microbial community was dominated by "Ferrovum", which is an acidophilic autotrophic iron-oxidizing bacterium and was not yet been validly described. Since the sub-cultivation of enrichment cultures containing "Ferrovum" encountered difficulties and resulted in loss of strains, oxidative stress was considered to be a possible reason for this. Therefore, the culture JA12 containing "Ferrovum" and Acidiphilium was incubated under different oxygen and carbon dioxide concentrations, as well as under anaerobic conditions. Compared to atmospheric conditions, microaerobic conditions enhanced bacterial survival. Incubation of the culture under increased carbon dioxide and decreased oxygen content affected the bacterial survival positively, while the incubation under anaerobic conditions was not favorable. Information about the novel genus "Ferrovum" regarding physiological characteristics will facilitate the handling of the bacteria. The knowledge about optimal storage conditions may make it more simple to provide active cultures for use in mine-water treatment.