[Removal of Cr from tannery sludge by bioleaching in air-lift reactor: a pilot study].
A bioleaching process performed in 280 L 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 1.5 m3/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 2.0 m3/h was considered as an optimum one for bioleaching in this trial. Cr removal efficiency could reach above 92.5% at 72 h. In the sludge bioleaching system dissolved oxygen increased obviously with the decrease of pH. Eventually, dissolved oxygen rised to 5 mg/L or more when aeration amount was maintained at 2.0 m3/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.
Chen
Hao
H
College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Zhou
Li-xiang
LX
Li
Chao
C
D001419:Bacteria / Q000378:metabolism; D001673:Biodegradation, Environmental; D019149:Bioreactors; D002857:Chromium / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D007220:Industrial Waste / Q000032:analysis / Q000517:prevention & control*; D010865:Pilot Projects; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology; D013633:Tanning
D007220:Industrial Waste; D012722:Sewage; D002857:Chromium