Stability of Metal Precipitates Formed after In Situ Bioprecipitation Induced by Sulfidogenesis

摘要

This study investigates the stability of the formed metal precipitates, after inducing in situ bioprecipitation (ISBP) in batch and column scale experiments. Samples were 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 during the batch tests was evaluated by various methods. Glycerol was found to be the most appropriate 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 donors also formed the most stable precipitates for the respective sites. The BIOMET method applied on the aquifer of site 2 and aquifer of 30 m depth of site 1 indicated that the immobilized Zn was not bioavailable. SEM/EDX performed on the pink precipitates formed on the aquifer in the lactate-N/P condition of site 3 showed that the main elements of the precipitates were Co and S. Results obtained for the column leaching tests for 2 sites (site 1 and site 3) also showed stable metal immobilization since no increased metal concentration was found for the tested substrate.