Integration of membrane technology in microalgae biorefineries

Abstract

The future of microalgae as a sustainable feedstock for biofuel and other products is still uncertain. Although productivity and environmental benefits surpass that of many other types of feedstock, the associated costs with production and downstream processing hinder this type of technology. The microalgae biorefinery approach addresses many of these issues in which upstream and downstream processes are important. Upstream technologies associated to nutrient recovery from waste effluents have been reviewed and discussed. Potentially, waste-derived nutrients will enable the formulation of optimal growth media from wastewater at lower costs. Microalgae dewatering is still seen as a major burden. A thorough review of the associated membrane processes in the literature has highlighted lack of consistency in terms of the influence of pore size and membrane materials. Moreover, only very few pilot-scale cost estimates could be found. The fractionation of microalgae products is perhaps the less developed area in the context of a microalgae biorefinery. Membrane filtration for the recovery of lipids, proteins and carbohydrates from microalgae is still an infant technology and major developments are expected to take place within the next few years. This review highlights the achievements, potential and future challenges of integrating membrane technology into microalgae-based biorefineries.