Bio-leaching studies were carried out in a 2L bioreactor- BIOSTAT-B® equipped with a PLC based controller at 20-40% (w/v) pulp density using enriched culture of A.ferrooxi-dans for Turamdih uranium ore (Jharkhand, India). With the enriched culture of Aferrooxidans adapted on Fe(II) at pH 2.0, 35°C and 20% (w/v) pulp density, a 98.3% uranium recovery was recorded in 14 days. The leaching of uranium in the bioreactor improved the dissolution rate by reduc-ing the time from 40 days in shake flask as per our ear-lier studies to 14 days. While investigating the import- ance of biogenic Fe (III) in the bio-leaching process a maximum recovery of 84.7% (1308 was observed at pH 2.0 and
20% (w/v) pulp density in 10h as compared to the uranium leaching of 38.3% in the control experiments. On raising the pulp density to 30%, uranium bio-recovery increased
to 87.6% in 10/i at pH 2.0 with <76,um size material. This showed a distinct advantage because of better mixing of slurry in the bioreactor with auto-controlled conditions that improved the kinetics
