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BACKGROUND
With increase in fossil fuels limitations there is increase in search for alternative ways for producing fossil fuels. It has brought into light the use of freshwater algae as a raw material for production of biodiesel. Algae is one of the greatest sources of biodiesel because of its high rate of growth without competing for availability of land. In comparison to other raw materials for biodiesel production like soybean, palm etc algae has more potential to produce biodiesel. Moreover, the biodiesel produced from algae are also biodegradable, non-toxic, free from Sulphur and the most important thing is the things that are leftover after fuel production can be utilized for production of ethanol as well as a potential soil fertilizer. Apart from that the biodiesel that is produced from algae possess high caliber to meet the global demand of fuels.
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REQUIREMENTS
Sample: Algal sample
Media: Bold basal media
Others: Condenser
Retort stand
Hot plate stirrer
1 L beaker, tube
250 ml round bottom flask
Sonicator
Centrifuge
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PROCEDURE
At first you have to select a good algal species that grows very easily and is easy to cultivate. It should have high lipid content and can be easily grown in laboratory. Then prepare media for the growth of algae. Then it’s time to prepare the culture. Culture is prepared under aseptic conditions, so that there is very less chance of contamination in the media and the culture.1 All the medium and glassware should be sterilized in an autoclave for about 15 min at a temperature of 121oC. Then about 5 ml of the algal culture is seeded to 2 L Schott bottle that is filled with sterilized distilled water containing BBM at 250C. For producing continuous light two fluorescent light is used and then keep it for aeration for about 12 days by bubbling air at a constant pressure. Then after culture, it’s time for harvesting the algal cells. Harvesting is done by centrifuging the culture at 8000 rpm for about 10 min.2 Then once centrifugation is over, discard the clear solution and collect the algal biomass and rinse it with de-ionized water for removing any remaining nutrients. Extraction is done by using the dry biomass, therefore a freeze dryer is used for drying the biomass before carrying out extraction. Drying is done by using a freeze dryer. Once freeze drying is done, its time to destroy the microalgae cells. It is carried out by placing the algal biomass along with distilled water in a 250 ml round bottom flask and is then sonicated for about 5 min that will completely lyse the cells. Now it’s time for extracting the oil. It is done by Soxhlet extraction method. Different solvent system is used for extracting oil like heptane, heptane: methanol (1:1), heptane: methanol (1:2), heptane: ethanol (1:1) and heptane: ethanol (1:2). With the help of a magnetic stirrer mix the algal biomass with the solvent at a rate of 600 rpm and temperature of 65oC.3 It will take about 5 long hours to extract the oil from the algal biomass. Then the mixture is centrifuged for about 2 minutes at 4000 rpm that separates it into three layers. Upper layer contains water, lower layer contains oil-solvent mixture and the middle layer contains biomass. The lower layer is collected and evaporated by using rotary evaporator for getting the algal oil. Then extraction is carried out taking into consideration various parameters like rate of mixing, time of extraction, temperature for increasing the biodiesel yield.3
Amount of biodiesel yield is calculated by following formula
Yield (%) = weight of oil extraction(g) / Weight if algae biomass(g)×100%.
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CONCLUSION
With high potential to grow in areas away from forest and farmland, biodiesel extraction from algae posses a very minimum chance of damage to the ecosystem and food chain. Algae also grow in sewages and power plant smokestacks, thus assisting in pollutant digestion. The biodiesel extracted from algae is also of good quality as compared to conventional biodiesel. All future research should concentrate in developing algae with high lipid content or some algae bioengineering methods for producing biodiesel, as it can proved to be one of the promising way for meeting the energy demand.
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REFERENCES
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Richmond A. Handbook of microalgal culture: biotechnology and applied phycology, John Wiley & Sons; 2008.
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Chisti Y. Biodiesel from microalgae. Biotechnology Advances, 2007;25(3):294-306.
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Picardo M, de Medeiros J, Monteiro J, Chaloub R, Giordano M, de Queiroz Fernandes Araújo O. A methodology for screening of microalgae as a decision-making tool for energy and green chemical process applications. Clean Technologies and Environmental Policy, 2013;15(2):275-291.
