Stability of Metal Precipitates Formed after In Situ BioprecipitationInduced by Sulfidogenesis

摘要

This study investigates the stability of the formed metal precipitates, afterinducing in situ bioprecipitation (ISBP) in batch and column scale experiments. Sampleswere collected from three different sites, with heavy metals present in various concentrations(site 1 and 2 : Zn; site 3 : Co). The stability of the metal precipitates formed duringthe batch tests was evaluated by various methods. Glycerol was found to be the mostappropriate carbon source for site 1; glycerol and lactate-N/P for site 2; glycerol, lactate-N/P, cheese whey and CAP18 for site 3. Stability tests suggested that these electron donorsalso formed the most stable precipitates for the respective sites. The BIOMETmethod applied on the aquifer of site 2 and aquifer of 30 m depth of site 1 indicated thatthe immobilized Zn was not bioavailable. SEM/EDX performed on the pink precipitatesformed on the aquifer in the lactate-N/P condition of site 3 showed that the main elementsof the precipitates were Co and S. Results obtained for the column leaching testsfor 2 sites (site 1 and site 3) also showed stable metal immobilization since no increasedmetal concentration was found for the tested substrate.