2.1. Culture conditions for the experimental organism
Chlorella minutissima, a fast-growing green microalga, was selected for this study. Axenic cultures of the test microalga was maintained in Erlenmeyer flasks with N 11 medium as per Soeder & Bolze (1981). The temperature was mentained at 25±2 °C with phtoperiod of 14 h and light intensity of 75 μmol photons m−2s−1 PAR.
For drying experiments, C. minutissima was cultivated in raceway ponds with volumetric capacity of 40,000 L each (14 × 4 × 0.75 m). Before cultivation in raceway ponds, the selected microalga was scaled-up in the UZn medium (Koley, Mathimani, Bagchi, Sonkar, & Mallick, 2019), and was acclimatized to the outdoor condition as detailed in Sonkar, Deb, & Mallick (2020). The raceway ponds were operated at 30 cm of culture depth with a corresponding culture volume of 16000 L. Harvesting of the microalgal biomass was carried by pH-induced flocculation using NaOH at pH 12 for 12 h following Koley, Prasad, Bagchi, & Mallick (2017).