Experimental Study of Microalgae Cultivation Based on Ag/CoSO4 Selective Light Permeability

The efficiency of biomolecular accumulation (lipids, proteins, carbohydrates) and biomass productivity of microalgae were affected by the spectrum of light during cultivation. In this study, a bilayer plate-type photobioreactor was designed to cultivate Chlorella protothecoides with spectral selectivity by nanofluids. The Ag/CoSO₄ nanofluid was located in the layer between microalgae suspension and light resource, acting as a light-transmitting object to culture Chlorella protothecoides. Compared to the cultivation without spectral selectivity, the production of microalgae biomass increased by 5.76% with spectral selectivity by Ag/CoSO₄ nanofluid and increased by 17.14% with spectral selectivity by CoSO₄ solution. Besides, the behavior of the spectral selectivity of Ag/CoSO₄ nanofluid was more favorable to the accumulation of nutrients in the microalgae (29.46% lipids, 50.66% proteins, and 17.86% carbohydrates). The results revealed that the spectrum of light was in a range between 600 and 700 nm when visible light passed through Ag/CoSO₄ nanofluid, promoting the accumulation of nutrients in microalgae. This investigation provides a new idea for the cultivation of outdoor microalgae through the regulation of the spectrum.