Harvesting of microalgae inoculum in culture medium by membrane ultrafiltration

Harvesting is a crucial step as it can represent 20 to 30 % of the overall cost of the whole process of microalgae exploitation for various applications such as cosmetics, neutracetic, food or energy. Generally, microalgae components are recovered after biomass dewatering and drying. In order to minimize energy requirements recovery would have to be performed from wet biomass by low-cost and low energy requirements technologies. For membrane processes, where pumping is generally the main operating cost, the culture medium is eliminated by permeation through a semi-permeable membrane. In this study, the dynamic cross-flow filtrations were performed in terms of permeation flux and maximum cell concentration reachable. The use of dynamic filtration system where the shear rate was independent on the feed flow, allow to reach better flux. The extrapolation to zero flux showed that it would be theoretically possible to achieve up to a factor of concentration close to 1000 was 200 g DM. L−1 (gdry matter. L−1).