The effect of photoperiod on microalgae cultivation exhibited a
significant influence towards microalgae photosynthetic activity
and growth rates in a typical cultivation system [31,32]. However,
it should be noted that microalgae with excessive of light exposure
would result to unwanted electricity consumption (energy waste)
and also inhibit the growth of microalgae [33]. Fig. 2 shows the
effect of photoperiod towards the growth of C. vulgaris. From the
figure, the growth of C. vulgaris was strongly affected by photoperiod,
with the highest biomass yield attained at 0.31 g/L through
continuous 24 h light illumination for 12 days (specific growth rate
of 0.228 day1). In addition, for photoperiod of 3 h, 6 h and 9 h, the
biomass attained were only 0.03–0.1 g/L which was exceptional
unsatisfactory. This result indicates that longer photoperiod will
result to continuous uptake of nutrients by C. vulgaris through
photosynthesis and subsequently, increase their biomass at the
same cultivation time. In other words, this result also indicates