Biorefinery concept in a microalgae pilot plant. Culturing, dynamic filtration and steam explosion fractionation

• A microalgae pilot plant with culturing capacity of 53 m3 was operated.
• CO2 fertilization for microalgae growth was tested.
• Sedimentation, centrifugation and dynamic membrane filtration were performed.
• Novel treatment by means of steam explosion was investigated.
• Steam explosion allowed breaking cell walls and improved lipid extraction.

A 53 m3 microalgae pilot plant with semi-closed photobioreactors has been operated in batch mode at Tarragona, where proper climatic conditions exist. Operations carried-out were microalgae culturing, concentration, cell disruption and lipid extraction. Culturing was performed with and without CO2 fertilization. pH was used to control CO2 dosing. With CO2 fertilization best microalgae concentrations were obtained. Productivities up to 19.9 g/m2/day were reached. Although sedimentation and centrifugation was performed, studies focused on dynamic membrane filtration as improved technique compared with conventional one. Significant fouling reduction was obtained by using a vibrational membrane setup. Cell disruption including product pre-extraction was performed by using steam explosion at moderate conditions, as novel technique for this application. Lipid extraction was performed by using conventional techniques with and without exploded material. The amount of lipids obtained from exploded material was higher than with non-exploded material, which shows that steam explosion provides a clear enhancement.

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