Desorption and dissolution of heavy metals from contaminated soil using Shewanella sp. (HN-41) amended with various carbon sources and synthetic soil organic matters.

Heavy metals in soil are considered a major environmental problem facing many countries around the world. Contamination of heavy metals occurs in soil due to both anthropogenic and natural causes. During the last two decades, extensive attention has been paid to the management and control of soil contamination. Decontamination of heavy metals in the soil has been a challenge for a long time. Microbial solubilization is one of promising process for remediation of heavy metals from contaminated sites. In this study, we attempted to treat soil contaminated with heavy metals using a facultative anaerobic bacterium Shewanella sp. (HN-41). The effect of carbon sources on the dissolution and conversion of heavy metals was first investigated using a defined medium containing 1 g of highly contaminated soil to select the most effective carbon source. Among three carbon sources, namely glucose, acetic acid and lactic acid, glucose at 10 mM was found to be the most effective. Therefore, glucose was used as a representative carbon source for the second part of the biological treatment in the defined medium, amended with humic acid (HA) and anthraquinone-2,6-disulfonate (ADQS), respectively. Among the heavy metals, iron and manganese exhibited the highest dissolution efficiency in the medium supplemented with glucose at 10mM. The rates of dissolution and removal of heavy metals were little bit higher in the medium amended with humic acid and ADQS. Per these results outlined above, a combined system of humic acid and ADQS incorporated with glucose was found to be effective for the removal of heavy metals from soil.