A Hybrid Microfluidic Differential Carbonator Approach for Enhancing Microalgae Growth: Inline Monitoring Through Optical Imaging

Abstract

Microalga biomass is considered as a potential feedstock for renewable energy owing to its high lipid content. Conventional microalgae cell culturing methods mostly require lengthy procedures and involve laborious and time-consuming steps. On the other hand, microalgae culturing in microfluidics offers several advantages over conventional methods, such as high sensitivity, enhanced mass and heat transfer, reduced runtime and cost, lower consumption of reagent, and better interaction of species. In this study, initially, a novel hybrid microfluidic differential carbonator (µ-DC) platform was constructed in-house. Then, the performance of this system was tested by microalgae culturing. In this regard, Picochlorum sp. was selected as a model microalgae cell due to its fast growth and high lipid content. The operating conditions for the microalgae growth were 2–6% (vol) inlet CO2 concentration, 49 µmole m2/s light intensity, and 1:0.025 inlet ratio of algae to media. Both spatial and temporal changes of the microalgae growth were investigated. A maximum microalgae growth after 45 h was found to be $$3.37\times {10}^{10}$$ cells/mL in a 50 µm depth cell culture (µ-CC), which is higher cell density than literature values. Such inflate of cell density can be attributed to the fact in improving the mass transfer and providing better contact of microalgae with the ingredients of the photosynthesis process. This remarkable improvement in the growth of cells is of significant importance for many applications, especially for biodiesel production.