title: Sequential removal of heavy metals ions and organic pollutants using an algal-bacterial consortium.
abstract: The residual algal-bacterial biomass from photosynthetically supported, organic pollutant biodegradation processes, in enclosed photobioreactors, was tested for its ability to accumulate Cu(II), Ni(II), Cd(II), and Zn(II). Salicylate was chosen as a model contaminant. The algal-bacterial biomass combined the high adsorption capacity of microalgae with the low cost of the residual biomass, which makes it an attractive biosorbent for environmental applications. Cu(II) was preferentially taken-up from the medium when the metals were present both separately and in combination. There was no observed competition for adsorption sites, which suggested that Cu(II), Ni(II), Cd(II), and Zn(II) bind to different sites and that active Ni(II), Cd(II) and Zn(II) binding groups were present at very low concentrations. Therefore, special focus was given to Cu(II) biosorption. Cu(II) biosorption by the algal-bacterial biomass was characterized by an initial fast cell surface adsorption followed by a slower metabolically driven uptake. pH, Cu(II), and algal-bacterial concentration significantly affected the biosorption capacity for Cu(II). Maximum Cu(II) adsorption capacities of 8.5+/-0.4 mg g-1 were achieved at an initial Cu(II) concentration of 20 mg l-1 and at pH 5 for the tested algal-bacterial biomass. These are consistent with values reported for other microbial sorbents under similar conditions. The desorption of Cu(II) from saturated biomass was feasible by elution with a 0.0125 M HCl solution. Simultaneous Cu(II) and salicylate removal in a continuous stirred tank photobioreactor was not feasible due to the high toxicity of Cu(II) towards the microbial culture. The introduction of an adsorption column, packed with the algal-bacterial biomass, prior to the photobioreactor reduced Cu(II) concentration, thereby allowing the subsequent salicylate biodegradation in the photobioreactor.
authors.affiliation: Department of Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, S-22100 Lund, Sweden. Raul.Munoz@biotek.lu.se
authors.forename: Raul
authors.initials: R
authors.lastname: Muñoz
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Alvarez
authors.forename: Adriana
authors.initials: A
authors.lastname: Muñoz
authors.forename: Enrique
authors.initials: E
authors.lastname: Terrazas
authors.forename: Benoit
authors.initials: B
authors.lastname: Guieysse
authors.forename: Bo
authors.initials: B
authors.lastname: Mattiasson
mesh_terms: D000327:Adsorption; D001673:Biodegradation, Environmental; D018441:Biofilms / Q000254:growth & development*; D018533:Biomass; D002708:Chlorella / Q000254:growth & development*; D007477:Ions; D019216:Metals, Heavy / Q000032:analysis*; D009930:Organic Chemicals / Q000032:analysis*; D043367:Ralstonia / Q000254:growth & development*; D013559:Symbiosis; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D007477:Ions; D019216:Metals, Heavy; D009930:Organic Chemicals; D014874:Water Pollutants, Chemical