Enhancement of biodiesel production from different species of algae

Abstract

Eight algal species (4 Rhodo, 1 chloro and 1 phaeophycean macroalgae, 1 cyanobacterium and 1 green microalga) were used for the production of biodiesel using two extraction solvent systems (Hexane/ether (1:1, v/v)) and (Chloroform/ methanol (2:1, v/v)). Biochemical evaluations of algal species were carried out by estimating biomass, lipid, biodiesel and sediment (glycerin and pigments) percentages. Hexane/ ether (1:1, v/v) extraction solvent system resulted in low lipid recoveries (2.3-3.5% dry weight) while; chloroform/methanol (2: 1, v/v) extraction solvent system was proved to be more efficient for lipid and biodiesel extraction (2.5 – 12.5% dry weight) depending on algal species. The green microalga Dictyochloropsis splendida extract produced the highest lipid and biodiesel yield (12.5 and 8.75% respectively) followed by the cyanobacterium Spirulina platensis (9.2 and 7.5 % respectively). On the other hand, the macroalgae (red, brown and green) produced the lowest biodiesel yield. The fatty acids of Dictyochloropsis splendida Geitler biodiesel were determined using gas liquid chromatography. Lipids, biodiesel and glycerol production of Dictyochloropsis splendida Geitler (the promising alga) were markedly enhanced by either increasing salt concentration or by nitrogen deficiency with maximum production of (26.8, 18.9 and 7.9 % respectively) at nitrogen starvation condition.