Making full use of lipid and carbohydrate in microalgae for joint production of biodiesel and bioethanol
may create a potential way to cut the high cost of single biofuel production from microalgae. Compared
with conventional unicellular oleaginous microalgae, filamentous microalgae Tribonema sp. is richer in
lipid and carbohydrate contents and lower protein content, thus, this study explores the suitability of
Tribonema sp. as a substrate for joint production of biodiesel and bioethanol. Acid hydrolysis is the key
step to saccharify wall cell into fermentable sugar and release lipid. Microalgae biomass (50 g/L) was acid
(3% H2SO4) hydrolyzed at 121 C for 45 min to reach the maximum hydrolysis efficiency (81.48%). Subsequently,
the lipid separated with hexane–ethanol from the hydrolysate was converted into microalgae
biodiesel and the conversion rate was 98.47%. With yeast Saccharomyces cerevisiae, the maximum ethanol
yield of 56.1% was reached from 14.5 g/L glucose in hydrolysate.