Baltic Sea microalgae transform cement flue gas into valuable biomass

Abstract

We show high feasibility of using cement industrial flue gas as CO2 source for microalgal cultivation. The toxicity of cement flue gas (12–15% CO2) on algal biomass production and composition (lipids, proteins, carbohydrates) was tested using monocultures (Tetraselmis sp., green algae, Skeletonema marinoi, diatom) and natural brackish communities. The performance of a natural microalgal community dominated by spring diatoms was compared to a highly productive diatom monoculture S. marinoi fed with flue gas or air–CO2 mixture. Flue gas was not toxic to any of the microalgae tested. Instead we show high quality of microalgal biomass (lipids 20–30% DW, proteins 20–28% DW, carbohydrates 15–30% DW) and high production when cultivated with flue gas addition compared to CO2–air. Brackish Baltic Sea microalgal communities performed equally or better in terms of biomass quality and production than documented monocultures of diatom and green algae, often used in algal research and development. Hence, we conclude that microalgae should be included in biological solutions to transform waste into renewable resources in coastal waters.