Synthesis of Biodiesel/Bio-Oil from Microalgae - Biotechnological Applications of Microalgae - page 107

the total lipid content in the tested microorganisms. The exothermic heat per dry
sample mass (kJ g −1 ) in the temperature range from 280°C to 360°C differentiated
the oleaginous from the non-oleaginous microorganisms. It was found that the heat
evolved from the oleaginous microorganisms was larger than that from the non-
oleaginous microorganisms in the specified temperature range. The sharpness of
the exothermic peak was also more distinct in the oleaginous microorganisms. Kim
et al. (2011) utilized the residual biomass of Nannochloris oculata as a biosorbent
for the removal of chromium from aqueous solutions. The biological route can also
be adopted for biodiesel synthesis. It is anticipated that biodiesel production will
increase in the coming years and there will be large amounts of residual biomass that
can be used for the treatment of wastewater. The process for the synthesis of biodiesel
and bio-oil from microalgae can be depicted through a flowchart (Figure 8.1).

Microalgae

Cultivation

Harvesting

De-watering and concentrating microalgae

Extraction of oil/lipids

Crude lipids (Neutral lipids & Pigments)

Neutral lipids (triglycerides, free fatty acids, hydrocarbons,
sterols, wax and sterol esters, and free alcohols)

Separation

Triglycerides and free fatty acids

Pyrolysis/thermochemical
catalytic liquefaction

Esterification/Transesterification

Bio-oil Biodiesel

FIGURE 8.1 Steps in the production of bio-oil and biodiesel from microalgae.