A correlation between the optical density of C. vulgaris and
biomass was pre-determined. Optical density was measured daily
at 540 nm [18] using spectrophotometer (Shimadzu UV mini-
1240). Then, 10 mL of sample were centrifuged at 10 × 1000 g for
5 min. The supernatant was slowly decanted back into the culture
medium whereas the microalgae biomass was dried in an oven at
100 ◦C for 24 h. All the samplings were performed in triplicate to
ensure the accuracy of the data. The correlation is shown in Eq.