A. Preparation of Algal Solution
The microalgal species used in this experiment is
Chlorella Vulgaris which is one of the dominant green algal
species in natural water. The algal seeds were obtained from
Center of Excellence for Marine Biotechnology of
Chulalongkorn University. The seeds were cultured in
Convay medium [20] and incubated for 7-14 days, which is
the period of log growth phase.
After incubation, 15 L of algal solution was prepared
using a Haemacytometer counting chamber to measure cell
density of the pre-cultured algae in order to calculate the
dilution ratio. Then, the algal volume was diluted with tap
water because the initial cell concentration was fixed at 108
cells/L. The initial pH was adjusted to desired value (6-8) by
using 1 N H2SO4 or 1 N NaOH reagent grade. The
conductivity of the algal solution after adjusting pH and
adding pre-cultured algae was 253±7 µS/cm