OPTIMIZATION OF GROWTH MEDIUM OF MARINE MICROALGAE Navicula sp. FOR LIPID PRODUCTION AS BIODIESEL FEEDSTOCK

• Main Author: SUSAN BRATANINGTYAS , DEWI
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/34890
• Institution: Institut Teknologi Bandung

World energy demand will increase to 45% until 2030 (International Energy Agency). Of 80% of that energy is supplied from fossil fuels that are non- renewable resources. This is true in Indonesia that it oils and natural gases deposit will be finished not more 25 years. In the future, the imbalance between demand and supply of fossil fuels causes a world energy crisis. Hence, we must find an alternative renewable fuel sources. Biofuels are the best candidate to replacement fossil fuels because of easily renewed, environmentally friendly, and sustained. In most countries, biofuels from corn, jatropha, palm, and soybean has been developed. However, the use of such oils for biodiesel feedstock will compete with food. Therefore, development of a new biodiesel feedstock should not interfere to oils for food. One of a potential organism possessing high lipid content for biodiesel feedstock is marine microalgae Navicula sp. The aim of this research was to search the best growth medium of Navicula sp. for lipid production. Three kinds of growth medium were examined: seawater medium, Walne medium, and modified medium (seawater medium enriched by basic elements nitrogen, phosphor, and silicon). The research methodology includes cultivation of microalgae Navicula sp., lipid extraction, and biodiesel production. Triacylglycerol and biodiesel compositions were determined by the mass spectrometry method. In addition, a flame test, kinematic viscosity, density, and internal energy of biodiesel were also determined. The results showed that the growth of marine microalgae Navicula sp. in modified medium was better than that of in both seawater and Walne medium. The cell density (106 cell/mL) of Navicula sp. cultivated in modified medium, seawater medium, and Walne medium was 21.6 after 7 days, 1.38 after 6 days, and 16.1 after 6 days, respectively, with biomass concentration of 2.54, 0.68, 2.16 g/L. The best concentration ratio (in mg/L) of N:P:Si in modified medium was 40:1:13. Marine microalgae Navicula sp. produced neutral lipids containing 10.65% POP, 39.54% POO, and 49.81% OOLn. Total lipid content obtained from Navicula sp. cultivated in modified and Walne medium were 34.16 and 26.64% wet mass, respectively, with lipid productivity of 124 and 90 mL/L culture/day, respectively. Microalgal biodiesel showed a flame when burn. The biodiesel products had a kinematic viscosity of 1.299 mm2/s, density value of 0.8347 g/mL, and internal energy of 0.9 J/mL. In conclusion, marine microalgae Navicula sp. was a promising source for producing lipid as biodiesel feedstock.