Utilisation of CO2 from Sodium Bicarbonate to Produce Chlorella vulgaris Biomass in Tubular Photobioreactors for Biofuel Purposes (original) (raw)
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Chlorella vulgaris was cultivated in two different 2.0 L-helicoidal and horizontal photobioreactors at 5 klux using the bicarbonate contained in the medium and ambient air as the main CO 2 sources. The influence of bicarbonate concentration on biomass growth as well as lipid content and profile was first investigated in shake flasks, where the stationary phase was achieved in about one half the time required by the control. The best NaHCO 3 concentration (0.2 g L −1 ) was then used in both photobioreactors. While the fed-batch run performed in the helicoidal photobioreactor provided the best result in terms of biomass productivity, which was (84.8 mg L −1 d −1 ) about 2.5-fold that of the batch run, the horizontal configuration ensured the highest lipid productivity (10.3 mg L −1 d −1 ) because of a higher lipid content of biomass (22.8%). These preliminary results suggest that the photobioreactor configuration is a key factor either for the growth or the composition of this microalga. The lipid quality of C. vulgaris biomass grown in both photobioreactors is expected to meet the standards for biodiesel, especially in the case of the helicoidal configuration, provided that further efforts will be made to optimize the conditions for its production as a biodiesel source.
Sustainability
Microalgae-based carbon dioxide (CO2) biofixation and biorefinery are the most efficient methods of biological CO2 reduction and reutilization. The diversification and high-value byproducts of microalgal biomass, known as microalgae-based biorefinery, are considered the most promising platforms for the sustainable development of energy and the environment, in addition to the improvement and integration of microalgal cultivation, scale-up, harvest, and extraction technologies. In this review, the factors influencing CO2 biofixation by microalgae, including microalgal strains, flue gas, wastewater, light, pH, temperature, and microalgae cultivation systems are summarized. Moreover, the biorefinery of Chlorella biomass for producing biofuels and its byproducts, such as fine chemicals, feed additives, and high-value products, are also discussed. The technical and economic assessments (TEAs) and life cycle assessments (LCAs) are introduced to evaluate the sustainability of microalgae CO2...
Global NEST International Conference on Environmental Science & Technology
The boosting of greenhouse gas (GHG) emissions into the atmosphere due to anthropogenic activity contributes significantly to climate change. According to the Green Deal by 2050, net zero greenhouse gas emissions must be achieved. Therefore, actions are needed in order to control GHG emissions. The research presents and discusses the optimization of the microalgae biomass cultivation phase and the harvesting process in an advanced membrane photobioreactor (mPBR) with the aim to improve its production for green fuel generation. Experimental activities are carried out by considering Chlorella vulgaris microalgae as photosynthetic microorganism. A dark/light cycle of 12/12 hours was implemented by varying the light intensity from 100 to 300 μmol m-2 s-1. Different L/G rate, by keeping the gas flow rate (G) constant at 100 ml/min and increasing the liquid flow rate recirculation (L) from 500 to 1500 L min-1, has been tested to boost up the productivity of microalgae. Results highlight o...
Reduction of CO2 by a high-density culture of Chlorella sp. in a semicontinuous photobioreactor
Bioresource Technology, 2008
The microalga incorporated photobioreactor is a highly efficient biological system for converting CO 2 into biomass. Using microalgal photobioreactor as CO 2 mitigation system is a practical approach for elimination of waste gas from the CO 2 emission. In this study, the marine microalga Chlorella sp. was cultured in a photobioreactor to assess biomass, lipid productivity and CO 2 reduction. We also determined the effects of cell density and CO 2 concentration on the growth of Chlorella sp. During an 8-day interval cultures in the semicontinuous cultivation, the specific growth rate and biomass of Chlorella sp. cultures in the conditions aerated 2-15% CO 2 were 0.58-0.66 d À1 and 0.76-0.87 g L À1 , respectively. At CO 2 concentrations of 2%, 5%, 10% and 15%, the rate of CO 2 reduction was 0.261, 0.316, 0.466 and 0.573 g h À1 , and efficiency of CO 2 removal was 58%, 27%, 20% and 16%, respectively. The efficiency of CO 2 removal was similar in the single photobioreactor and in the six-parallel photobioreactor. However, CO 2 reduction, production of biomass, and production of lipid were six times greater in the six-parallel photobioreactor than those in the single photobioreactor. In conclusion, inhibition of microalgal growth cultured in the system with high CO 2 (10-15%) aeration could be overcome via a high-density culture of microalgal inoculum that was adapted to 2% CO 2. Moreover, biological reduction of CO 2 in the established system could be parallely increased using the photobioreactor consisting of multiple units.
Gravity : Jurnal Ilmiah Penelitian dan Pembelajaran Fisika
A closed photobioreactor design has been fabricated, aimed to determine the basic concept for microalgae Chlorella vulgaris development. This study employed a flat-plate type with dimensions of 16x20x25 cm with the effectiveness of 3000 ml culture media and two 20 watt 220 volt tungsten halogen lamps, which were placed on the right and left sides of the reactor with a light intensity of 1000 lux. This study employed two photobioreactors, type-I without CO 2 supply and type-II with CO 2 supply as much as 25%. The initial cell density of Chlorella vulgaris culture was 14,694 x10 5 cells/ml; then observations were made every day using a Haemocytometer. O 2 concentration data were collected every day 3 times with irradiation time of 1, 6, and 9 hours using the O 2 gas sensor (KE-50 type). The determination of the O 2 concentration value in the photobioreactor on the 3 rd day was 0.69%.
Processes, 2021
By converting bicarbonates via Chlorella vulgaris photosynthesis, one can obtain valuable biofuel products and find a route toward carbon-derived fossil fuel conversion into renewable carbon. In this research, experiments were carried out in the PhotoBioCREC prototype under controlled radiation and high mixing conditions. Sodium bicarbonate (NaHCO3) was supplied as the inorganic carbon-containing species, at different concentrations, in the 18 to 60 mM range. Both the NaHCO3 concentrations and the organic carbon concentrations were quantified periodically during microalgae culture, with the pH being readjusted every day to the 7.00 level. It was found that sodium bicarbonate was converted with a selectivity up to 33.0% ± 2.0 by Chlorella vulgaris. It was also observed that the reaction rate constant for inorganic carbon conversion was 0.26 ± 0.09 day−1, while the maximum reaction rate constant for organic carbon formation was achieved with a 28 mM NaHCO3 concentration and displayed ...
CO2 utilization in the production of biomass and biocompounds by three different microalgae
Engineering in Life Sciences
CO 2 utilization in the production of biomass and biocompounds by three different microalgae The atmospheric CO 2 increase is considered the main cause of global warming. Microalgae are photosynthetic microorganisms that can help in CO 2 mitigation and at the same time produce value-added compounds. In this study, Scenedesmus obliquus, Chlorella vulgaris, and Chlorella protothecoides were cultivated under 0.035 (air), 5 and 10% (v/v) of CO 2 concentrations in air to evaluate the performance of the microalgae in terms of kinetic growth parameters, theoretical CO 2 biofixation rate, and biomass composition. Among the microalgae studied, S. obliquus presented the highest values of specific growth rate (μ = 1.28 d −1), maximum productivities (P max = 0.28 g L −1 d −1), and theoretical CO 2 biofixation rates (0.56 g L −1 d −1) at 10% CO 2. The highest oil content was found at 5% CO 2 , and the fatty acid profile was not influenced by the concentration of CO 2 in the inflow gas mixture and was in compliance with EN 14214, being suitable for biodiesel purposes. The impact of the CO 2 on S. obliquus cells' viability/cell membrane integrity evaluated by the in-line flow cytometry is quite innovative and fast, and revealed that 86.4% of the cells were damaged/permeabilized in cultures without the addition of CO 2 .
Energy Conversion and Management, 2018
The optimum concentration of dissolved carbon in the microalgal culture medium is a vital requirement for enhanced biomass production. The present study investigates the effect of supplying NaHCO 3 with CO 2 as the inorganic carbon source to enhance the utilization efficiency of CO 2 for maximum FAME productivity of Chlorella sp. HS2. The specific growth rate (0.615 d −1), biomass productivity (530.1 mg L −1 d −1), CO 2 biofixation rate (996.4 mg L −1 d −1), FAME productivity (141.8 mg L −1 d −1) and FAME content (26.76%) were found to be maximized at NaHCO 3 concentration of 0.5 g L −1 with 1% (v/v) CO 2 enriched air (0.25 vvm flow rate) supplementation in shake flask condition. The FAME productivity (169.37 mg L −1 d −1) and FAME content (31.2%) were 1.19 and 1.16 times higher respectively in the flat panel photobioreactor than in shake flask condition. Fatty acid profile and biofuel properties show suitability for biodiesel production. The economic assessment revealed that combining supplementation of both carbon sources greatly reduces the carbon supply costs, from 8.92Kg−1whenonlyNaHCO3wasusedasthecarbonsourcedownto8.92 Kg −1 when only NaHCO 3 was used as the carbon source down to 8.92Kg−1whenonlyNaHCO3wasusedasthecarbonsourcedownto0.86 Kg −1 when 1% CO 2 was supplied alongside NaHCO 3. These findings show that combined application of NaHCO 3 and CO 2 is the more cost-effective approach of supplying carbon source to microalgae for FAME production.