Flotation of Algae, Bacteria and Other Microorganisms

Ice/Water Interface: Zeta Potential, Point of Zero Charge, and Hydrophobicity

“…4 are of different hydrophobicities because ice is hydrophilic or only slightly hydrophobic, hexadecane is highly hydrophobic with a contact angle equal to 110°, and the air bubble, due to the similarity to the oil droplet (flotation, the presence of structural hydrophobic forces) (18), is also considered a highly hydrophobic medium. Diamonds and bacteria are also hydrophobic but their hydrophobicity is much lower than that of hydrocarbons because the contact angle of bacteria is usually only between 10°and 20° (19) and for the diamond sample shown in Fig. 4, it is between 2°and 12° (20).…”

Systems and economic analysis of microalgae ponds for conversion of CO{sub 2} to biomass. Final report

“…In "electroflotation" electrolysis is used to produce small H2 bubbles, but power consumptions are high (see Shelef et al, 1984). Flotation can even be effected by "froth flotation", simple sparging with fine bubbles (see Smith, 1988, for review). The algal cuiture itself can generate fine gas bubbles after mechanical pumping, as it is supersaturated with 0 2 during day time.…”

“…0 3 ) on enhancing algal flocculation (Sukenik, 1987;Betzer and Argaman, 1980). Another ignored process, which deserves some attention, is "foam fractionation" (or "foam floatation"), in which algae are concentrated in the foam generated by bubblers by the attachment of the algae cells to the gas bubbles in the presence of surfactants (Levin et al, 1962;Honeycutt et al, 1983, see Smith, 1988 for a review). However, harvesting efficiencies are low and cost likely high.…”

Removal of metal ions from dilute solutions by sorptive flotation

“…Several interesting applications of flotation in biotechnology have been published since the pioneering article of Gaudin almost 40 years ago (Gaudin et al, 1960) and recently have been reviewed (Smith, 1989;Thomas and Winkler, 1987). Foam flotation for microbial recovery has been investigated from the viewpoints of the effects of biochemical variables (microbial surface activity and strain, microbial age, cultivation conditions, and wall properties) and engineering variables (flotation mechanisms, effect of dispersed-phase and continuous-phase velocities, column geometry, biomass concentration, solution pH, etc.)…”

“…However, many enzymes (e.g., catalase, amylase, and urease) were found to be quite stable under foaming conditions (Carlesson, 1989). Important examples include the recovery of Penicillin G in a flotation column, the effective separation of bacteria and other organic materials (causing color) from surface waters, the fractionation of proteins produced by yeast in a batch bioreactor, the recovery of proteolytic enzymes from nonconventional biological sources and the flotation of Escherichia coli, Bacillus subtilis, B. megaterium, and Serrata marcescens, the foam separation of Proteus vulgaris and Pseudomonas fluorescens (among other bacteria), and the separation of Saccharomyces carlsbergensis cells from their broth (Smith, 1989;Matis et al, 1994).…”