Effect of light intensity on biofuel production from green alga Chlorella vulgaris (original) (raw)
Related papers
2015
The application of microalgal oil for energy purposes continues to present a number of challenges, including the optimization of culture conditions. In this study, the two light intensities at 2.5 Klux and 5 Klux were used in light-dark cycles of 8:16, 16:8, 0:24 and 24:0 hour to investigate the effect of light intensity and photo period on biomass production and lipid productivities in microalgae, Chlorella vulgaris and Nannochloropsis sp. in view of optimizing the illumination level for biodiesel production through algal oil. Chlorella vulgaris and Nannochloropsis sp were cultured in Guillard and Rither`s f/2 media for 21 days and 14 days growth periods respectively in a laboratory scale closed experimental set-up. The cultures were aerated with mechanical aerators. Finally, cells were harvested by flocculation and dry weight and the percentage lipid content were estimated. Significantly higher average dry matter yield was observed when the cells cultured under 5 Klux light intens...
Four different intensities treatments were used to stimulate the biodiesel production from two local isolated algae: Chlorella vulgarisBerjerinck and Nitzschiapalea (Kütz.) Smith. Also the study included the effect of light intensity on growth rates and primary product (carbohydrate and protein). The treatment 300μE\m 2 \sec was recorded the highest lipid content 10% of dry weight (DW), highest carbohydrate content (18% of DW) and highest protein content (58% of DW) for C.vulgaris. While the alga N. paleathe highest values were recorded for lipid content (48% of DW), carbohydrate contents (22% of DW) and 15% of DW for protein content at treatments 300, 125 and 268μE\m 2 \sec respectively. The results revealed that Stearic acid content was increased significantly at the treatments 300μE\m 2 \sec for N. palea while the Oleic acid content increased significantly at 300μE\m 2 \sec for C.vulgaris. The present study recorded Chrysocapsaplanctonica (West&West) Plscher as new recorded to Iraq algae flora.
Biotechnology and Bioprocess Engineering, 2015
Microalgae are viable sources of biological compounds for biodiesel production. In this study, effects of various types of nitrogen sources and nutrients concentrations in the growth medium and different LED light wavelengths and intensities on biomass production of green algae Chlorella vulgaris were investigated. Warm white light with 80 µmol/m 2 /sec light intensity was determined as the optimal light for biomass production. The results indicated that microalgae growth with urea as nitrogen source was higher than that of other nitrogen sources such as sodium nitrate, ammonium carbonate and ammonium chloride. Maximum biomass concentration (1.37 g/L) was obtained under the following media compositions: urea 0.25 g/L, K 2 HPO 4 0.04 g/L, MgSO 4 • 7H 2 O 0.06 g/L, and ammonium ferric citrate 0.01 g/L. Microalgae growth data under the different light wavelengths and intensities were fitted with a mathematical model.
Complementary Production of Biofuels by the Green Alga Chlorella vulgaris
There is increasing growing concerns about global warming and rising of oil prices. The aim of the current work was to evaluate the potential of the green alga Chlorella vulgaris as a cheap renewable energy source in term of biofuels. Alga was hetero-trophically grown under both vegetative and induction-conditions. Induction was proceed to enhance cell metabolites mainly oils (for biodiesel) and carbohydrates (for bioethanol-production). BG-II growth medium was used for vegetative growth, while such medium was enriched by ferrous sulfate, sodium acetate and sodium chloride under high light irradiation for induction purposes. De-fatted dried algal cells were subjected to bioethanol production through three different treatments prior yeast fermentation to increase the fermentable sugars content after oils were extracted from algae. This includes direct treatment by Tricoderma sp., acid hydrolysis and molasses addition. Saccharomyces cerevisiae was used in fermentation action. Results indicated that the oil content of stressed algal cultures was raised to be 14.8% with 26.7% of total carbohydrates versus to 32.14% of crude protein. Fatty acids profile resulted in an increase of saturated fatty acids by about 10.65 %, while unsaturated fatty acids were decreased by 18.57%. Third day of incubation seems to be the optimum for direct fermented or pre acid hydrolyzed-alga in terms of yeast biomass, consumed sugar and alcohol percent By such time 15% of molasses represented the same manner. Also, the maximum alcohol content (38.7%) by acid hydrolyzed; while direct fermentation resulted in 28.7% versus to 36.3% of molasses addition.
Studies on the Growth of Chlorella vulgaris in Culture Media with Different Carbon Sources
Diminishing oil reserves, rising oil prices and a significant increase in atmospheric carbon dioxide levels have led to an increasing demand for alternative fuels. Microalgae have been suggested as a suitable means for fuel production because of their advantages related to higher growth rates, higher photosynthetic efficiency and higher biomass production , compared to other terrestrial energy crops. During photosynthesis, microalgae can fix carbon dioxide from different sources, including the atmosphere, industrial exhaust gases and soluble carbonate salts. To determine the most optimal conditions for the growth of Chlorella vulgaris in order to produce lipids that can be transformed into biodiesel fuel, different nutritional conditions were investigated. For this purpose, three media, namely Jaworski's medium, an enriched solution from modified Dual Solvay process and natural mineral water, were prepared and analyzed for biomass production, chlorophyll content and lipid content. The best growth resulted in an enriched solution from the modified Solvay process. This medium was diluted in different dilution ratios (1:100, 1:50, 1:10) and the best results were obtained in a medium diluted in a 1:10 ratio on the fifth day of culturing (3.72 · 10 6 cells mL –1 ; 4.98 mg mL –1 chlorophyll a).
Many species of microalgae produce lipids/oils that can be extracted for biofuel production. High oil-yielding microalgae can be produced in open ponds or closed photobioreactors. Illumination sources should be chosen carefully because illumination cost is the major cost in microalgae production in closed systems. In this research Chlorella kessleri, one of the highest oil producing microalgae producing 18-58% oil on a dry basis, was grown in a closed photobioreactor. Three illumination sources of Blue LED, Red LED and Fluorescent lamps were used separately. The algae grown under these illumination sources were evaluated for the cell count, cell weight, cell size and lipid content and their biodiesel production potential were assessed. The results showed that fluorescent light was the most efficient illumination source producing the highest number of cells (3.5x10 6 cell/mL) and red LED light was the most effective illumination source producing the highest weight (2.7g/L).
Bioethanol Production from Green Alga Chlorella Vulgaris Under Different Concentrations of Nitrogen
2014
Ethanol fuel or ethyl alcohol is an alternative to gasoline; it can be used as additive to gasoline, and also as a feed chemical in the transesterification process for biodiesel. A number of bio feed stocks are currently being experimented for biofuel production; algae have emerged as one of the most promising sources for biofuel production. The locally isolated microalga chlorella vulgaris was used in the current study to test their ability to production bioethanol through stimulated in different nitrogen concentration treatments (0, 4, 8, 12 g/l), and effect of nitrogen concentrations on the content of primary products (carbohydrate and protein), also the yield of bioethanol. The growth curves of C. vulgaris were different among the treatments. The stationary phase was identified as day 5, 9, 12 and 14 in treatments 0, 4, 8 and 12 g/l nitrogen respectively. The growth rate (K) increased from 0.14 to 0.20 for the treatments 8 g/l and 0 g/l respectively. The shortest doubling time (...
The effect of different light spectrum and CO 2 concentrations on the growth and lipid content of Micractinium pusillum and Ourococcus multisporus was investigated. The highest biomass yields (2.9 and 2.6 g-dry cell weight l À1) were observed for M. pusillum and O. multisporus, respectively, at 5% CO 2 with red light illumination. Red light spectrum with 5% CO 2 supported the highest lipid contents (20% and 27%) and lipid productivity (32 and 36 mg l À1 d À1) for M. pusillum and O. multisporus, respectively. The highest fatty acid methyl esters content for both microalgal species was observed under red light spectrum and 5% CO 2 conditions, with the oleic acid fraction ranging between 35% and 37%. This study showed that the red light spectrum and 5% CO 2 were the optimum conditions for maximum growth, lipid content and lipid productivity of both microalgae species, which could be further exploited to establish a microalga-based biodiesel production strategy. V