title: Enhanced Cr bioleaching efficiency from tannery sludge with coinoculation of Acidithiobacillus thiooxidans TS6 and Brettanomyces B65 in an air-lift reactor.
abstract: Bioleaching process has been demonstrated to be an effective technology in removing Cr from tannery sludge, but a large quantity of dissolved organic matter (DOM) present in tannery sludge often exhibits a marked toxicity to chemolithoautotrophic bioleaching bacteria such as Acidithiobacillus thiooxidans. The purpose of the present study was therefore to enhance Cr bioleaching efficiencies through introducing sludge DOM-degrading heterotrophic microorganism into the sulfur-based sludge bioleaching system. An acid-tolerant DOM-degrading yeast strain Brettanomyces B65 was successfully isolated from a local Haining tannery sludge and it could metabolize sludge DOM as a source of energy and carbon for growth. A combined bioleaching experiment (coupling Brettanomyces B65 and A. thiooxidans TS6) performed in an air-lift reactor indicated that the rates of sludge pH reduction and ORP increase were greatly improved, resulting in enhanced Cr solubilization. Compared with the 5 days required for maximum solubilization of Cr for the control (single bioleaching process without inoculation of Brettanomyces B65), the bioleaching period was significantly shorten to 3 days for the combined bioleaching system. Moreover, little nitrogen and phosphorous were lost and the content of Cr was below the permitted levels for land application after 3 days of bioleaching treatment.
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, PR China. dfang@ouc.edu.cn
authors.forename: Di
authors.initials: D
authors.lastname: Fang
authors.forename: Li-Xiang
authors.initials: LX
authors.lastname: Zhou
mesh_terms: D042763:Acidithiobacillus / Q000378:metabolism*; D001203:Ascomycota / Q000378:metabolism*; D019149:Bioreactors; D007221:Industry; D012722:Sewage / Q000382:microbiology*; D013633:Tanning
chemical_list: D012722:Sewage