title: Bioleaching of spent hydrotreating catalyst by acidophilic thermophile Acidianus brierleyi: Leaching mechanism and effect of decoking.
abstract: Bioleaching of spent hydrotreating catalyst by thermophillic archae Acidianus brierleyi was investigated. The spent catalyst (containing Al, Fe, Ni and Mo as major elements) was characterized, and the effect of pretreatment (decoking) on two-step and spent medium leaching was examined at 1% w/v pulp density. Decoking resulted in removal of carbonaceous deposits and volatile impurities, and affected the solubility of metal compounds through oxidization of the metal sulfides. Nearly 100% extraction was achieved using spent medium leaching for Fe, Ni and Mo, and 67% for Al. Bioleaching reduced nickel concentration in the leachate below the regulated levels for safe waste disposal. Chemical (i.e. abiotic) leaching using equimolar concentration of sulfuric acid produced by the bacteria during two-step process achieved a lower leaching efficiency (by up to 30%). Results indicated that A. brierleyi successfully leached heavy metals from spent catalyst.
authors: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576, Singapore.
authors: Abhilasha
authors: A
authors: Bharadwaj
authors: Yen-Peng
authors: YP
authors: Ting
mesh_terms: D041541:Acidianus / Q000378:metabolism*; D006256:Hazardous Waste / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000032:analysis*; D008670:Metals / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000032:analysis; D056951:Photoelectron Spectroscopy
chemical_list: D006256:Hazardous Waste; D007220:Industrial Waste; D008670:Metals; D009532:Nickel