Effects of Depth and Concentration of Digestate on Growth of Three Microalgal Species

Abstract

In order to design a culture system for microalgal biomass production with a low cost and convenient cell collection, growth performance of mixtures of microalgal cells, including Euglena gracilis, Chlorella vulgaris, and Dunaliella tertiolecta cultured in a volume of 1 L were investigated at a PPFD of 300 µmol m -2 s -1 at the surface of the solution with continuous illumination at 30 °C. Each culture container contained diluted digestate at concentrations of 5, 10, 15, 20, and 50 %. Sample cells for counting cell number were collected daily. Pseudospecific growth rates (µ s ) of each species at each depth were calculated as cellular multiplication rates using number of cells per time. The average µ s of each species was highest in 5 % digestate. The average µ s of all three microalgal species (0.035 h -1 ) was observed in all layers in 5 % digestate solution. The µ s of each species was highest in 5 % digestate (0.048 h -1 , 0.041 h -1 , and 0.022 h -1 , respectively for C. vulgaris, E. gracilis, and D. tertiolecta). In conclusion, E. gracilis, C. vulgaris, and D. tertiolecta showed the highest specific growth rate in 5 % digestate.

Evaluation of Chlorella vulgaris and Scenedesmus obliquus growth on pretreated organic solid waste digestate

“…detected for both strains. Growth rate value obtained in AC and AUF mixotrophic and control conditions were similar to those obtained byUggetti et al (2014) andKhanh (2016) on S. obliquus and C. vulgaris on digestate, where they observed a wide μ values variation, ranged between 0.2 and 1 d -1 on digestate and control associated with several parameters such as light intensity, inoculum size, digestate turbidity and composition. As reported by Bouterfas et al (Bouterfas et al, 2002) a possible growth rate increase was linked to higher light irradiation used (400-420 μmol m -2 s -1 or 29.6-31 klux) and the temperature stable at 35 °C.…”