Redox transformation and biogeochemical interaction of heavy metals in Korean soil using different treatment columns in the presence of Shewanella sp.

The redox transformation and biogeochemical interactions of heavy metals in soil was examined using facultative anaerobic bacterium Shewanella sp. (HN-41) in batch mode and with small scale columns. A preliminary study was carried out to determine the influence of various glucose concentrations (10, 20 and 30 mM) on the bacterial growth and releasing of heavy metals from soil using a defined medium. The results showed that the heavy metals were released tremendously in the medium supplemented with 30 mM glucose. Therefore, 30 mM glucose was used as the sole carbon source for further studies. Then, the dissolution and redox transformation of heavy metals were studied using small scale columns. Bacterially enriched synthetic water with and without glucose and soil organic matter, such as humic acid (HA) and anthraquinone-2,6-disulphonate (ADQS), were supplied to each column. Among the treatments in the column, the dissolution and redox transformation of heavy metals was highest in the synthetic water supplemented with glucose and ADQS. The efficiency was relatively low without the organic substrates and bacterial inoculum. These results clearly show that the addition of electron donor (glucose) and electron shuttles (ADQS) assists a maximum transformation of heavy metals from soil/sediment.