Use of Red and Blue Light-Emitting Diodes (LED) and Fluorescent Lamps to Grow Microalgae in a Photobioreactor

Abstract

High oil content microalgae are a source for biofuel production. They can be produced in open ponds or closed photobioreactors. To efficiently grow such microalgae, illumination for photosynthesis, CO2 consumption, and the pH and nutrient content of the growth medium must be monitored and precisely controlled. In a closed photobioreactor, illumination is the most critical parameter because it is the most expensive factor of algae production and must be operated 24 h per day. In this research, Chlorella kessleri (UTEX 398) microalgae were grown in photobioreactors. All parameters were identical, except the source and intensity of the illumination. The light sources included red light-emitting diodes (LED), blue LED, and fluorescent lights. Growth of the microalgae was observed for seven days and the effects of the three illumination sources on cell count, cell weight, and cell size were determined. In the first experiment, in which the current of all three light sources was the same, red LED produced the highest number of cells with the highest weight while blue LED light produced the largest cells. In the second experiment, in which the light intensity was the same for all three light sources, the highest weight was again achieved with the red LED. Thus, we suggest that most advantageous production system may be to use a red light initially to produce the desired cell concentration, then switch to a blue light to increase cell size.

Illumination Policies for Stichococcus sp. Cultures in an Optimally Operating Lab-Scale PBR toward the Directed Photosynthetic Production of Desired Products

“…The same observations were recorded by Oldenhof et al (2006), who pointed out that when Chlamydomonas reinhardtii cultures were subjected to blue light, cells were continuously growing for a longer period and attained larger sizes than under red light [26]. Similar results were obtained by Koc et al (2013), who found that Chlorella kessleri cells grown under blue LED light were larger than those grown under red or white fluorescent light, while red light resulted in higher biomass concentration than blue LED light, even though the average cell size was smaller [27]. In a study by Rendón et al (2013), who tried to elucidate the effect of CO 2 supply and illumination of C. vulgaris cultures at different light wavelengths, the highest biomass production was found when algal cultures were supplied with 8.5% CO 2 and exposed to white light [28].…”

“…(a) (b) In contrast to these results, a recent study on S.bacillaris alleged that the use of blue or red light did not seriously affect the culture growth kinetics [31], and yet several other published articles stated that red light is commonly suggested for biomass productivity enhancement in green microalgae [14,[24][25][26][27]. This is justified on the basis of the concur- Elaborating on the effect of the light type, it was unambiguously concluded that the specific wavelength indeed affects Stichococcus sp.…”

Influence of Light Conditions on Microalgae Growth and Content of Lipids, Carotenoids, and Fatty Acid Composition

“…In Parachlorella kessleri UTEX 398, red light stimulates cell formation, while blue light stimulates cell growth [148]. The authors believe this can be used in the Parachlorella kessleri production run by first applying red light to obtain the desired cell concentration and then switching to blue light to increase cell size.…”

Effect of Different Light Wave Lengths on the Growth and Oil Content of Chlorella Vulgaris

“…Total power of emission of the white lamps is higher than those of the other light sources, because of the differences in the respective light spectra. On the contrary, red LED light was found to be the most effective in cell division and dry weight accumulation, while blue LED light was the most effective in cell enlargement (Koc et al, 2013).…”