title: Removal of heavy metals using a brewer's yeast strain of Saccharomyces cerevisiae: the flocculation as a separation process.
abstract: In this work, a brewer's yeast strain was used to remove heavy metals from a synthetic effluent. The solid-liquid separation process was carried out using the flocculation ability of the strain. The yeast strain was able to sediment in the presence of Cu2+, Ni2+, Zn2+, Cd2+ and Cr3+, which evidences that the flocculation can be used as a cheap and natural separation process for an enlarged range of industrial effluents. For a biomass concentration higher than 0.5 g/l, more than 95% of the cells were settled after 5 min; this fact shows that the auto-aggregation of yeast biomass is a rapid and efficient separation process. Cells inactivated at 45 degrees C maintain the sedimentation characteristics, while cells inactivated at 80 degrees C lose partially (40%) the flocculation. The passage of metal-loaded effluent through a series of sequential batches allowed, after the second batch, the reduction of the Ni2+ concentration in solution for values below the legal limit of discharge of wastewater in natural waters (2mg/l); this procedure corresponds to a removal of 91%. A subsequent batch had a marginal effect on Ni2+ removal (96%). Together, the results obtained suggest that the use of brewing flocculent biomass looks a promising alternative in the bioremediation of metal-loaded industrial effluents since the removal of the heavy metals and cell separation are simultaneously achieved.
authors.affiliation: Chemical Engineering Department, Superior Institute of Engineering from Porto Polytechnic Institute, Rua Dr António Bernardino de Almeida, 431, 4200-072 Porto, Portugal.
authors.forename: Manuela D
authors.initials: MD
authors.lastname: Machado
authors.forename: Mónica S F
authors.initials: MS
authors.lastname: Santos
authors.forename: Cláudia
authors.initials: C
authors.lastname: Gouveia
authors.forename: Helena M V M
authors.initials: HM
authors.lastname: Soares
authors.forename: Eduardo V
authors.initials: EV
authors.lastname: Soares
mesh_terms: D018533:Biomass; D005427:Flocculation; D006358:Hot Temperature; D019216:Metals, Heavy / Q000302:isolation & purification*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D019216:Metals, Heavy; D014874:Water Pollutants, Chemical