title: Concentration of Cupriavidus necator cells by flocculation and sedimentation.
abstract: Separation and cells concentration constitute important stages in most biotechnological processes. Particularly, use of flocculation/sedimentation can improve significantly the extraction of biopolymers accumulated by microorganisms and the biodegradation of xenobiotic compounds by cell sludge. In this work the use of tannin and aluminum sulphate (Al2(SO4)3) as flocculating agents for concentration of cells of Cupriavidus necator DSM 545 is evaluated. Cells were grown in broth nutrient medium in Erlenmeyer flasks, submitted to orbital agitation of 160 rpm at 30 °C for 21 h. The optimal concentrations of flocculating agents, as determined with a standard jar test method, were equal to 2,800 mg/L for tannin and 800 mg/L for Al2(SO4)3, allowing for recovery of 95% of the cells in both cases. Obtained flocs presented density and average diameter of 1.03 g/mL ± 0.01 g/mL and 158 μm ± 19 μm for tannin and of 1.05 g/mL ± 0.01 g/mL and 146 μm ± 14 μm for Al2(SO4)3, respectively. Batch settling tests were performed in order to determine the operational capacity of continuous settlers to be used for separation of the investigated flocculent suspensions. Finally, cultivation of cells using flocs as inoculum indicated that the cells remained viable after flocculation with usage of the optimum flocculating agent concentrations.
authors: Department of Chemical Engineering, Federal University of Pernambuco, Rua Prof. Artur de Sá, s/n, Cidade Universitária, 50740-521, Recife, PE, Brasil. leandro.finkler@gmail.com.
authors: Leandro
authors: L
authors: Finkler
authors: Department of Chemical, Catholic University of Pernambuco, Rua do Príncipe, 526, Boa Vista, 50050-900, Recife, PE, Brasil.
authors: Christine Lamenha
authors: CL
authors: Luna-Finkler
authors: Chemical Engineering Program, COPPE, Federal University of Rio de Janeiro, CP: 68502, Cidade Universitária, 21945-970, Rio de Janeiro, RJ, Brasil.
authors: José Carlos
authors: JC
authors: Pinto
authors: Chemical Engineering Program, COPPE, Federal University of Rio de Janeiro, CP: 68502, Cidade Universitária, 21945-970, Rio de Janeiro, RJ, Brasil.
authors: Tito Livio Moitinho
authors: TL
authors: Alves
keywords: Cells concentration; Cupriavidus necator; Flocculation; Sedimentation; Tannin