title: Bioleaching of spent fluid catalytic cracking catalyst using Aspergillus niger.
abstract: The use of the fungus Aspergillus niger for the bioleaching of heavy metals from spent catalyst was investigated, with fluid catalytic cracking (FCC) catalyst as a model. Bioleaching was examined in batch cultures with the spent catalysts at various pulp densities (1-12%). Chemical leaching was also performed using mineral acids (sulphuric and nitric acids) and organic acids (citric, oxalic and gluconic acids), as well as a mixture of organic acids at the same concentrations as that biogenically produced. It was shown that bioleaching realised higher metal extraction than chemical leaching, with A. niger mobilizing Ni (9%), Fe (23%), Al (30%), V (36%) and Sb (64%) at 1% pulp density. Extraction efficiency generally decreased with increased pulp density. Compared with abiotic controls, bioleaching gave rise to higher metal extractions than leaching using fresh medium and cell-free spent medium. pH decreased during bioleaching, but remained relatively constant in both leaching using fresh medium and cell-free spent medium, thus indicating that the fungus played a role in effecting metal extraction from the spent catalyst.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore.
authors.forename: Khin Moh Moh
authors.initials: KM
authors.lastname: Aung
authors.forename: Yen-Peng
authors.initials: YP
authors.lastname: Ting
mesh_terms: D001234:Aspergillus niger / Q000378:metabolism*; D001711:Biotransformation; D002384:Catalysis; D003247:Conservation of Natural Resources; D007220:Industrial Waste / Q000517:prevention & control*; D019216:Metals, Heavy / Q000378:metabolism*; D012037:Refuse Disposal / Q000379:methods*; D017641:Zeolites / Q000378:metabolism*
chemical_list: D007220:Industrial Waste; D019216:Metals, Heavy; D017641:Zeolites