Foam separation of microorganisms has been investigated with varying success by many workers, usually a t high rates of gas flow. Microflotation was developed to overcome some of the disadvantages inherent in these high gas-flow-rate processes and is introduced in this paper as a new technique for the foam separation of microorganisms at low gas-flow rates. With microflotat>ion, a stable surface phase is produced by adding an insoluble collector such as a long-chain fatt>y acid or amine. The formation of an irrsoluble surface phwe eliminates the need for high foaming. Low rat,es of gas flow are used resulting in a more efficient separation and a less voluminous and drier surface phase upon which to collect, the microorganisms. The efficiency of this technique is also improved by using flotation aids such as frothers and floccu1ent)s. Frothers are used to improve the collector properties of the surfactant and to refine further the small bubbles produced by a very fine sparger. Small concentrations of flocculents, such as alum, are used to partially agglomerate the organisms and provide sites for adsorption of collector. The work described in this paper is preliminary in nature, designed to illustrate that a low flow-rate process may be used to separate microorganisms and to stimulate further research. The applications discussed are removal of the bacterium, Escherichia coli, using lauric acid and alum, and two species of algae, Chlamydmmas reinhardtii and Chlorella ellipsoidea, using stearylamine without alum. The frother used was ethanol.

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