A Simple Biogeochemical Process Removing Arsenic from a Mine Drainage Water

Arsenic is a toxic element commonly found in mining environments. The present study aimed to determine the influence of the indigenous bacterial population on the biogeochemical evolution of arsenic concentration in a mine drainage water. Biological As(III)-oxidizing activity was detected in diverse micro-environments along the water stream, from the source to the discharge point. Laboratory experiments showed that the bacterial population promoted As(III) and Fe(II) oxidation in conditions close to those of the site, i.e., temperature, water composition and oxygen availability. Immobilization of bacteria on pozzolana in a column bioreactor increased oxidation rates compared to on-site natural conditions: As concentration in the bioreactor outlet was less than 50 μg L −1 , whereas on-site total As concentration at the discharge point is close to 100 μg L −1 . The highest As(III) removal rate in the inoculated column reached 1900 μg L −1 h −1 and As(III) removal rate in the non-inoculated blank column was ...