Abstract:
Biodiesel is one of the alternative fuels obtained by the trans-esterification of triglyceride oil with
monohydric alcohol. Few studies have been conducted for microalgae producing biodiesel under
Sri Lankan condition. The objective of this study was to find out the effect of light intensity and
duration of light supply on growth of microalgae in indoor condition in the Department of
Agricultural Engineering, Faculty of Agriculture. The Guillard and Ryther's F medium was
selected as the medium for microalgae cultivation. The 5 ppt diluted sea water was used for
growing the pure culture of Nanachloropsissp. The growing media was volumed upto 5 L from 10
ml. The experiment was carried out with different light intensities during different time durations.
The provided light intensities were 950,1800 and 3000 lux and different time durations were given
as 12 hrs and 24 hrs due to examine the effect of duration of light supply on photo-inhibition of
microalgae. The oil content of each sample was extracted using Soxhelt unit. The effect of light
intensity on dry matter yield and oil content of microalgae is significant and positive relationship
was observed at 12 hrs light duration. The dry matter content can be increased further by increasing
the light intensity higher than 3000 lux. The effect of duration of light supply on dry matter content
of micro algae is significantly different and a positive relationship was observed. The oil content
of microalgae was significantly different between the light supply durations. Higher oil percentage
was observed under 12 hrs light duration, therefore algae cultivation can be done in outdoor
condition under natural day light to get more oil yield.
