Influence of light intensity and photoperiod on energy efficiency of biomass and pigment production of Spirulina (Arthrospira platensis)

Abstract

Biomass and photosynthetic pigments production of cyanobacteria, in particular Spirulina (Arthrospira platensis), depend on light intensity. Production cost of Spirulina cultivation in photobioreactor illuminated with LED is strongly related to light cost. This work is aimed to evaluate the effects of light intensity and photoperiod on the energy efficiency of biomass and pigment production of Spirulina platensis UTEX 1926. Cultures illuminated with white light-emitting diodes (LED) were carried out in batch mode cultivation. Three lighting scenarios with different light intensities were tested: two with a constant light intensity at 80 and 160 μmol · m−2 · s−1 and one with modulated light intensity. Concerning photoperiod, three cycles of light:dark (h:h) (24:00, 20:04 and 16:08) were studied under light intensity at 160 μmol · m−2 · s−1. Concerning Spirulina biomass and pigment production (phycocyanin, chlorophyll and carotenoids), it is found that the lower intensity tested allows a substantial increase of the process energy efficiency. Concerning the influence of the photoperiod, it has been found that the longer the off time is (up to 08 h 00 a day), the higher is the energy efficiency for Spirulina biomass as well as for pigmentary production.