Monochromatic light filters to enhance biomass and carotenoid productivities of Dunaliella salina in raceway ponds.

[Display omitted] • Down-regulation of sunlight to red and blue photons reduces photoinhibition by 60% • Red light induced active division rate and increased carbohydrate and lipid contents. • Protein content was high under blue wavelength with a low cell proliferation rate. • Cell size reduction or enlargement is a function of light wavelengths. • Coverage of ponds with wavelength-selective filters minimizes evaporation loss by 57% Monochromatic blue and red wavelengths are more efficient for light to algal biomass conversion than full-spectrum sunlight. In this study, monochromatic light filters were used to down-regulate natural sunlight to blue (400–520 nm) and red (600–700 nm) wavelengths to enhance biomass productivity of Dunaliella salina in outdoor raceway ponds. Growth indices such as cell size, pigment concentrations, biomass yield, photosynthetic efficiency, and major nutritional compositions were determined and compared against a control receiving unfiltered sunlight. Results showed that red light increased biomass productivity, lipid, and carotenoid contents but decreased cell volume, chlorophyll production, and cell weight. Conversely, blue light increased cell volume by 200%, cell weight by 68%, and enhanced chlorophyll a and protein contents by 35% and 51%, respectively, over red light. Compared to the control treatment, photoinhibition of D. salina cells at noon sunshine was decreased 60% by utilizing optical filters on the pond's surface. [ABSTRACT FROM AUTHOR]