Removal of Cr from Tannery Sludge by Bioleaching in Air-lift Reactor: A Pilot Study
空气提升式反应器处理制革污泥的中试研究

A bioleaching process performed in 280L air-lift reactor was developed for extracting Cr from tannery sludge. Cr removal efficiency under different aeration amount with a range from 1.0 m3/h to 3.0 m3/h was investigated. The results showed that the sludge could be homogeneous quickly for different aeration treatment even if aeration amount was as low as 1.0 m3/h. But the obvious effect of aeration amount on pH decrease and subsequent Cr dissolution in tannery sludge during bioleaching was observed. If the aeration amount was below 1.5m3/h , it at least took 90 h to reach 80% Cr removal efficiency. In the light of Cr removal efficiency and energy consume, the aeration amount of 2.0m3/h was considered as an optimum one for bioleaching in this trial. Cr removal efficiency could reach above 92.5% at 72h. In the sludge bioleaching system dissolved oxygen increased obviously with the decrease of pH. Eventually, dissolved oxygen raised to 5mg/L or more when aeration amount was maintained in 2.0m3/h or more. Therefore, it was suggested that the aeration amount in ALR could be adjusted to a lower level in the late stage of tannery sludge bioleaching in order to save operation cost.