Patent GB-984403-A (GB)
Title: Harvesting algae
IPC: A01G33/00
Filed: 1963-05-27
Abstract: Algae cells of, for example, Chlorella pyrenoidosa or Chlorella ellipsoidea, are separated from a liquid (water) by acidifying the liquid medium thereby causing the algae cells to be buoyed up to the surface of the liquid medium, passing one or more gases (air) through the medium so as to cause a foam containing the algae to form upon the surface of the liquid medium and separating the foam from the liquid medium.  In order to harvest green algae cells and viable bleached algae cells from a liquid medium containing them, the green algae cells to be buoyed to the surface, there is passed through the liquid medium a gas which is not assimilated by the bleached algae (air, nitrogen, hydrogen, argon and other gases of Group O of the Periodic Table) so as to cause a foam containing the green algae cells to form upon the surface of the liquid medium, which foam is then separated, and there is then passed through the residual liquid medium a gas which is assimilated by the bleached algae (carbon dioxide or an air/carbon dioxide mixture containing 5% or more carbon dioxide) whereby the bleached algae are buoyed to the surface and separated in foam.  The method may be employed for separating algae from mixtures of algae with bacteria, protozoa, non-viable physiological cellular structures and particulate mineral matter. Examples are given.ALSO:Algae cells of, for example, Chlorella pyrenoidosa or Chlorella ellipsoidea, are separated from a liquid (water) by acidifying the liquid medium thereby causing the algae cells to be buoyed to the surface of the liquid medium, passing one or more gases (air) through the medium so as to cause a foam containing the algae to form upon the surface of the liquid medium and separating the foam from the liquid medium.  In order to harvest green algae cells and viable bleached algae cells from a liquid medium containing them, the liquid medium is acidified thereby causing the green algae cells to be buoyed to the surface, there is passed through the liquid medium a gas which is not assimilated by the bleached algae (air, nitrogen, hydrogen, argon and other gases of Group O of the Periodic Table) so as to cause a foam containing the green algae cells to form upon the surface of the liquid medium, which foam is then separated, and there is then passed through the residual liquid medium a gas which is assimilated by the bleached algae (carbon dioxide or an air/carbon dioxide mixture containing 5% or more carbon dioxide) whereby the bleached algae are buoyed to the surface and separated in foam.  The method may be employed for separating algae from mixtures of algae with bacteria, protozoa, non-viable physiological cellular structures and particulate mineral matter.  Examples are given.ALSO:Algae cells of, for example, Chlorella pyrenoidosa, or Chlorella ellipsoidea, are separated from a liquid (water) by acidifying the liquid medium thereby causing the algae cells to be buoyed to the surface of the liquid medium, passing one or more gases (air) through the medium so as to cause a foam containing the algae to form upon the surface of the liquid medium and separating the foam from the liquid medium.  In order to harvest green algae cells and viable bleached algae cells from a liquid medium containing them, the liquid medium is acidified thereby causing the green algae cells to be buoyed to the surface, there is passed through the liquid medium a gas which is not assimilated by the bleached algae (air, nitrogen, hydrogen, argon and other gases of Group O of the Periodic Table) so as to cause a foam containing the green algae cells to form upon the surface of the liquid medium, which foam is then separated, and there is then passed through the residual liquid medium a gas which is assimilated by the bleached algae (carbon dioxide or an air/carbon dioxide mixture containing 5% or more carbon dioxide) whereby the bleached algae are buoyed to the surface and separated in foam. The method may be employed for separating algae from mixtures of algae with bacteria, protozoa, non-viable physiological cellular structures and particulate mineral matter.  Examples are given.