The three initial cell densities investigated were about 0.45,
0.75 and 1 cm1 (i.e. 0.15, 0.25 and 0.35 g/L in biomass) of absorbance
which was measured at OD686. The growth characteristics
of algae under the three different initial cell densities maintained
an increasing trend as shown in Fig. 2. The biomass dry weight
increased with the increasing of initial cell density from 0.45 to
1 cm1 of absorbance. During the whole cultivation period the
dry weight of biomass at initial cell density of 0.45 cm1 was
slightly lower than that of the other two. At the end of algae incubation,
the maximum harvested biomass dry weight of microalgae
was about 1.15 g/L at the initial cell density of 1 cm1. However,
the dry weight was about 0.9 g/L and 1 g/L when the initial cell
density was 0.45 and 0.75 cm1 respectively. It could be seen that
the biomass showed a slight increase at higher initial cell density
after 13 days cultivation. The results indicated that microalgae at
higher initial cell density could better adapt to the cultivation environment
to obtain higher growth rate and biomass production.
High initial cell density could mitigate the significant change of
growth conditions. The previous study also confirmed that high
cell density of microalgae inoculated was beneficial for better
adapting the environment [10].