Acid mine drainage remediation with simulated permeable reactive barrier filled with fly ash and its composite materials as reactive media

Abstract

ABSTRACT Fly ash and its composites are used as the reactive media of permeable reactive barrier to solve the pollution problem of acid mine drainage. Four simulation models (reaction column) of permeable reactive barrier were established, including Column 1 with fly ash, Column 2 with acid-modified fly ash, Column 3 with a mixture of fly ash, and sulfate-reducing bacteria, and Column 4 with immobilized particles of fly ash combined with sulfate-reducing bacteria. The removal effect of different reactive media in PRB on acid mine drainage was investigated. Results showed that fly ash and its composites could treat acid mine drainage, and the order was: Column 4 > Column 3 > Column 1 > Column 2. The average effluent pH and oxidation-reduction potential values of Column 4 were 7.03 and −236 mV, respectively. The maximum removal percentages of chemical oxygen demand, SO4 2-, Fe2+, and Mn2+ in acid mine drainage by Column 4 were 83%, 85%, 99%, and 84%, respectively. Compared with Column 1 and Column 3, the immobilized particles of fly ash combined with sulfate-reducing bacteria in Column 4 can not only improve the treatment effect of fly ash, but also effectively reduce the influence of external environment on sulfate-reducing bacteria activity, so it is suitable to be used as PRB reactive media to repair acid mine drainage.