Dissolved air flotation and centrifugation as methods for oil recovery from ruptured microalgal cells

Solvent-free microalgal lipid recovery is highly desirable for safer, more sustainable and more economical microalgal oil production. Dispersed air flotation and centrifugation were evaluated for the ability to separate oil and debris from a slurry mixture of osmotically fractured Chaetoceros muelleri cells with and without utilizing collectors. Microalgal oil partially phase-separated as a top layer and partially formed an oil-in-water emulsion. Although collectors, such as sodium dodecyl sulphate enhanced selective flotation, by just adjusting the pH and cell concentration of the mixture, up to 78% of the lipids were recovered in the froth. Using centrifugation of fractured microalgal slurry resulted in removal of 60% cell debris and up to 68.5% of microalgal oil was present in the supernatant. Both methods, centrifugation and flotation provided options for separation of microalgal oil from C. muelleri slurry with similar fatty acid recoveries of 57% and 60%, respectively.