Effect of Selected Light Spectra on the Growth of Chlorella spp. (Chlorophyta)

Abstract

The possibility for simultaneous production of chemical and electrical energies from a single microalgae cultivation plant is opening a new chapter in the efficient use of resources to maximize biomass productivity. In the current study, the effect of  selected monochromatic lights (blue, red and pink) from spectrally selective filters on the biomass productivity of semi-continuously grown Chlorella spp. was  investigated under laboratory conditions using light emitting diodes (LEDs). The temperature variations inside of the customized light boxes containing cultures under different light spectra were significantly different (p < 0.001). Cell density of the alga under the different light treatments was not similar and ranked as White > Pink > Blue > Red. The biomass productivity was highest under the white light  (60.07±9.38 mg L^-1 d^-1 dry weight, DW) and varied significantly (p = 0.004) among the treatments. However, productivities under the white (60.07±9.38 mg L^-1 d^-1 DW) and pink (56.25±9.85 mg L^-1 d^-1 DW) lights was statistically insignificant (p = 0.551). The result shows that biomass productivity of the alga, Chlorella spp., can be manipulated through targeted supply of specific spectral bands (e.g. pink light). Therefore, the remaining portions of the spectrum which are not utilized by the alga for growth can potentially be converted to electricity through a robust and highly efficient photovoltaic cell.

Keywords: Biomass productivity, Chlorella spp., Electricity, Light spectra, Photovoltaic