Carbon dioxide delivery and resulting biomass separation in microalgae cultivation using triethanolamine

Abstract

This study investigates a novel use of triethanolamine (TEA), a well-known carbon dioxide (CO2) - capturing chemical, to simultaneously deliver CO2 and separate microalgae biomass from the growth media in microalgae cultivation processes. For this purpose, the growth and nutrient utilization rates of Chlorella sp., were monitored at different concentrations of TEA saturated with 15% of CO2 in a gas mixture. In addition, the total inorganic carbon content in the growth media was followed in order to estimate the CO2 delivery rates. The highest growth and nutrient utilization rates occurred at 20 and 30 mM TEA concentrations, which results in 2.5-fold increase in biomass production rate at these TEA concentrations. More than 85% of the produced biomass was successfully separated from the medium by flotation facilitated by the release of oxygen and CO2 gases to the air from the oversaturated growth media, as well as the surfactant characteristics of TEA.