Continuous cultivation and flotation of Hansenula polymorpha and Saccharomyces cerevisiae in an integrated pilot plant reactor-flotation column-system
Abstract In a 300-1 stirred tank reactor provided with a foam separator, Hansenula polymorpha and Saccharomyces cerevisiae were cultivated continuously in the absence of antifoam agents, and the cells were recovered continuously from the cultivation medium in a flotation column, 3.6 m high, 10 cm inner diameter, which was directly connected to the reactor. The following flotation performances were attained: cell concentration in the foam liquid CS = 45.3 g l−1, cell concentration in the flotation residue CR = 1.03 g l−1 at a cell concentration in the medium (feed) CP = 5.4 g l−1 with H. polymorpha;, and CS = 139.2 g l−1, CR = 0.00 g l−1 at CP = 4.8 g l−1 with S. cerevisiae, both of them cultivated at C-limitation, and CS = 115.6 g l−1, CR = 0.05 g l−1, at CP = 2.18 g l−1 with H. polymorpha at P-limitation (0.11 g l−1 KH2PO4). Practically all cells were recovered from the medium and the following enrichments were attained: CS/CP = 8.4 (C-limitation with H. polymorpha), CS/CP = 29.1 (C-limitation with S. cerevisiae), CS/CP = 53.1 (P-limitation: 0.11 g l−1 KH2PO4 with H. polymorpha). With laboratory- and pilot-scale equipment, comparable results were attained.