Lipid selective milking from chlorella vulgaris in aqueous-organic biphase system
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Date
2018
Authors
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Publisher
Universiti Teknologi Malaysia
Abstract
Milking (without killing the microalgae cell) using biocompatible organic solvent is a potential extraction technique in microalgae biotechnology. Simultaneous production and extraction reduces the energy intensive harvesting, dewatering and drying and heavy nutrient input involved in microalgae biofuel production. Suitable cultivation condition and media composition having appropriate amount of nutrients enhance lipid production from microalgae. This study demonstrated the milking of lipid under modified bolds basal soil extract medium (SE-BBM) and blue light emitting diode (LED) light intensity and photoperiod of Chlorella vulgaris (C.vulgaris) using biocompatible organic solvents in an aqueous- organic biphase system. C.vulgaris was cultivated in modified SE-BBM under three different light intensities (100, 200 and 300 µmol m-2s-1) of blue LED, and light (L) and dark (D) regimes (12: 12, 16: 08 and 24: 00 h L: D) for number of hours L: D at constant pH of 6.8 and temperature of 25°C for 13 days. Variations on physical parameters such as growth and lipid content of C.vulgaris were analyzed. Maximum lipid content (23.5%) and growth rate (1.26 d-1) were obtained under blue LED intensity of 200 µmol m-2s-1 with light and dark regimes of 12:12 L: D hours within the reduced cultivation time of 8 days. Lipid milking was performed under 10, 15 and 20 vol % of dodecane and tetradecane concentrations within the aqueous-organic biphase system up to four cycles. Lipid content in solvent phase was analysed by Nile red fluorescent method. Lipid recovery was 47 ± 5% during the first cycle of 8 days. Solvent recovery ratio of dodecane was higher than tetradecane. Long term milking was done in a two liter flask under 20 % dodecane for 30 days. Fatty acid methyl ester (FAME) components were analysed by gas chromatography. The analysis of FAME components showed that the milking technique is effective at 20% dodecane producing appropriate biofuel components and has high potential to milk lipids at large scale from C.vulgaris without killing the cells. This milking technique is an ideal technique towards sustainable and energy efficient production of biofuel from microalgae
Description
Thesis (PhD. (Bioprocess Engineering))
Keywords
Microalgae—Biotechnology, Lipids—Biotechnology, Biomass energy—Research