AN EVALUATION OF THE POTENTIAL BENEFITS OF AN ACIDOPHILIC PROTOZOAN IN ACID MINE DRAINAGE SYSTEMS

Euglena mutabilis, a photosynthetic, acidophilic protozoan, forms benthic mats in acid mine drainage (AMD) systems associated with coal mining activities. Previous investigations show that E. mutabilis may have a beneficial effect on AMD environments by removing iron from acidic effluent through intracellular sequestration and via oxygenic photosynthesis that drives precipitation of reduced iron. In this study, laboratory experiments were conducted to determine the amount of iron removal by E. mutabilis and to evaluate whether the biological activity of the microorganism also impacted solution pH and trace element content. A series of test solutions, consisting of four simulated and one actual AMD solutions, were inoculated with E. mutabilis cells. In addition, a series of the same solutions were left uninoculated as controls. The test solutions were allowed to evolve over a period of two months with periodic sampling to determine solution pH and concentrations of dissolved iron and trace elements.

Preliminary results indicate that upon inoculation with E. mutabilis the initial pH of the test solutions decrease by as much as 1.5 pH units. After inoculation, no significant changes in solution pH occurred during the first 28 days of the experiment. The test solutions, as well as precipitated material, are currently being analyzed for iron and trace metal content by inductively coupled plasma mass spectrometry.