Methods are disclosed for dewatering an aqueous suspension of microalgae, especially Dunaliella salina, with a Jameson cell. The algal cells are ruptured sufficiently to promote froth flotation of the cells from the suspension. The algal suspension is introduced into the top of the Jameson cell downcomer and passed through an orifice plate therein to generate a free liquid jet of the suspension. The jet is plunged downwardly through a gas and the gas is transported with the jet through a gas and liquid interface into the algal suspension. The momentum of the jet is dissipated, which disperses the gas into fine bubbles. The fine bubbles are intimately contacted with the aqueous suspension in cocurrent downward flow in a collection zone to absorb the algal bodies onto the surfaces of the bubbles. A froth of bubble and algal agglomerates is formed and collapsed to obtain a dewatered algal concentrate. The Jameson cell can be operated at sufficient inlet pressures so that the algal cells are ruptured by passing them through the orifice rather than in a separate step.