[Removal of Cr from tannery sludge by acidophilic Thiobacilli].

The removal of Cr from tannery sludge by bioleaching technology was reported in the paper. Batch experiments involved the inoculation of acidophilic Thiobacilli and addition of elemental sulfur as their substrate. Results showed that Cr removal of 100% could be obtained after 8 days of bioleaching. The oxidation of added sulfur by acidophilic Thiobacilli decreased sludge pH value which caused the solubilization of Cr from tannery sludge. A threshold pH of 2.0 existed for Cr solubilization from tannery sludge, below which Cr solubilization efficiency sharply increased to 80%-100%. This study might provide a newly attractive alternative for the treatment and disposal of heavy metal-contaminated solid wastes.