The Influence of Artificial Lighting Systems on the Cultivation of Algae: The Example of Chlorella vulgaris (original) (raw)
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The Egyptian Journal of Chemistry, 2021
At present, the major body of research is focused on weaning the world from fossil fuels. The problem is that the world is running out of fossil fuel. Therefore, an alternative source must be identified. The biofuels are promising alternatives. In the case of petrodiesel, a promising alternative is biodiesel production from algae. The ability of microalgae to generate large quantities of lipids with a fast growth rate made them superior biodiesel producers. Using light-emitting diodes (LEDs) as an energy source in microalgal cultivation was recently increased owing to its large spectrum, endurance, and low-energy utilization. Changes in cultivation conditions, limited capabilities of harvesting light, and self-shading of microalgae were the most important problems. Therefore, the photobiostimulation of algae using LEDs radiation led to an increase in algal growth rate which results in increased lipid production. This research investigated the influence of monochromatic LEDs on the growth of Chlorella sorokiniana microalga. At the first phase, microalgae growth and algal biomass significantly increased under red LEDs [2.3 g/L], blue LEDs [1.8 g/L], green LEDs [0.7 g/L], and white LEDs (0.6) g/L as a control, respectively. At the second phase, microalgal growth and algal biomass significantly increased under red LEDs [2.9 g/L], blue LEDs 2.3 g/L, and white LEDs (1.5) g/L as a control, respectively. The percentage of extracted oil (%) or the yield of extracted oil of microalgae was 10.38 % (white LEDs), 16.94 % (blue LEDs), and 15.55 % (red LEDs) respectively. It was concluded that the photobiostimulation of algae using LEDs led to the enhanced weight of algal biomass, therefore increased of lipids and biodiesel production. The red LEDs were the best one in terms of increasing the weight of algal biomass. The blue LEDs were the best one in terms of increasing the percentage of extracted oil. However, the green LEDs were not effective.
Journal of Biotechnology, 2012
Green microalgae have recently drawn attention as promising organisms for biofuel production; however, the question is whether they can grow sufficient biomass relative to limiting input factors to be economically feasible. We have explored this question by determining how much biomass the green microalga Chlorella vulgaris can produce in photobioreactors based on highly efficient light-emitting diodes (LEDs). First, growth results were improved under the less expensive light of 660 nm LEDs, developing them in the laboratory to meet the performance levels of the traditional but more expensive 680 nm LEDs by adaptive laboratory evolution (ALE). We then optimized several other key parameters, including input superficial gas velocity, CO 2 concentration, light distribution, and growth media in reference to nutrient stoichiometry. Biomass density thereby rose to approximately 20 g dry-cell-weight (gDCW) per liter (L). Since the light supply was recognized as a limiting factor, illumination was augmented by optimization at systematic level, providing for a biomass productivity of up to 2.11 gDCW/L/day, with a light yield of 0.81 gDCW/Einstein. These figures, which represent the best results ever reported, point to new dimensions in the photoautotrophic performance of microalgal cultures.
2020
In the current study, two types of algae Spirulina platensis and Coelastrella terrestris were exposed to two different types of lighting, LED and Halogen with different light intensities, to identify the effect of lighting on the growth of algae and their production of chlorophyll-a, protein, carbohydrates and lipids, as well as investigating anti-properties. Bacterial to these algae extracts. The study showed that there are differences in the growth rates of the algae under study and exposed to the two types of lighting, as the intensity of illumination 2000 LED was the best when it recorded the highest concentration of the chlorophyll tincture for both algae while the lighting intensity was 2500 and 3000 lux for the source of halogen lighting is the best in the production of chlorophyll for algae r, Q, respectively, with respect to proteins, the highest concentration of 0.48 mg/ml was recorded by algae spirulina at the intensity of illumination of the 2000 lux LED and 0.501 mg/ml ...
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.
In this study, culture of Chlorella vulgaris in food effluent and its specific growth rate, biomass, chlorophyll a, chlorophyll b, total carotenoids and removal of nitrate and phosphate under the red light emitting diodes (R-LED) and fluorescent light (FL) were investigated. For these purposes, C. vulgaris were cultured in two concentrations of 10% (treatment of 10% W), 15% (treatment of 15% W) as mixotrophic model (Mix) of food effluent and BBM as autotrophic model (Auto) under red LED and fluorescence light for 15 days. Therefore, six different treatments were assigned as; BBM + FL (Auto), 10%W + FL (Mix), 15%W + FL (Mix), BBM + R-LED (Auto), 10%W + R-LED (Mix) and 15%+R-LED (Mix). The experiment conditions were 24 hours light photoperiod, water temperature of 26°C and a light intensity of 300 µmol photons m− 2 s− 1 for red LED light and 35 µmol photons m− 2 s− 1 for fluorescent treatments. The highest amount of chlorophyll a (1.60 mgL− 1), cell density (46.6 × 106 cell/mL), speci...
Food technology and biotechnology, 2019
The cultivation of Chlorella sp., the most abundant microalga in the Persian Gulf, took place in a novel pyramid photobioreactor (PBR), a modified version of plate PBR, consisting of four completely separate equal-volume chambers. In this study we used two light sources incident in each chamber: light-emitting diode (LED) at various wavelengths (red, white and blue) of 108 µmol/(m2·s) photosynthetic photon flux density as internal lighting, and the same photon flux density for external white lighting. PBR served to study the effects of light sources on chlorophyll a production, maximum specific growth rate (µmax), biomass productivity rate (rp) and photon performance. The results showed that the highest chlorophyll a production was obtained under red LED illumination. The highest values for rp, µmax and photon performance were obtained under white light.
Effect of Light Intensity on the Growth of Chlorella Variabilis
Deu Muhendislik Fakultesi Fen ve Muhendislik, 2016
Microalgae are increasingly employed for production of a wide range of industrial chemicals. Light intensity is an important parameter affecting microalgae cell growth. Analysis of light penetration into the algae culture broth is important for an efficient photobioreactor design. In this study, effect of light intensity on the growth of microalgae species Chlorella variabilis was investigated in a compartmentalized photobioreactor system. The optimal range of light intensity for highest growth rate (0.037 h-1) and cell concentration (0.30 gdw/L) was found to be 17-36 klux, lower light intensities yielded in significantly slower growth and lower cell concentrations. Photoinhibition effect was clearly observed at light intensities above 36 klux. Maximum photobioreactor depth which can provide 95% of the maximum growth rate was determined to be 8 cm.
Biomass and Bioenergy, 2015
To increase microalgae biomass production and support high density cultures in photobioreactors artificial illumination systems have been designed to increase photosynthetic activity. Supplemental lighting systems are commonly composed by a combination of chlorophyll (a + b) strongly absorbed wavelengths, while weakly absorbed wavelengths are not present. At this work we compared the photosynthetic activity and biomass production induced by chlorophyll (a + b) strongly versus weakly absorbed wavelengths in Scenedesmus bijuga microalgae cultures at different biomass densities. Photosynthetic activity and biomass production induced by 4 different wavelengths using LEDs (blue-peak at λ470 nm; green-peak at λ530 nm; red-peak at λ655 nm; and white-4100 K) were measured and analyzed on high-density cultures of Scenedesmus bijuga. As culture density increased the chlorophyll (a + b) weakly absorbed green light penetrated deeper into the samples inducing higher oxygen evolution at culture concentration of 1.45 g L-1 compared to the chlorophyll (a + b) strongly absorbed red light. High-density culture (2.19 g L-1) cultivated under green light showed higher biomass production rate (30 mg L-1 d-1) with a 8.43% biomass growth in a 6-day period compared to the same quantum flux of red light that induced 4.35% biomass growth on the same period. The integration of green LEDs into photobioreactors lighting apparatus could improve the existing systems composed predominantly by red and blue LEDs increasing biomass productivity of high-density cultures at latter stages of microalgae cultivation.
Engineering in Life Sciences, 2012
A newly designed and constructed LED illumination device for commercial cylindrical bioreactors is presented for application in microalgal cultivations and investigation of growth kinetics. An ideally illuminated volume is achieved by focusing the light toward the center of the reactor and thereby compensating the mutual shading of the cells. The relevant biomass concentration for homogeneous illumination depending on reactor radius was determined by light distribution measurements for Chlamydomonas to 0.2 g/L (equal 0.435 optical density at 750 nm). It is shown that cultivation experiments with the newly designed illumination device operated in batch mode can be successfully applied for determination of growth rates and photo conversion efficiencies. The exact knowledge of physiological reactions of specific strain(s) and the estimation of relevant parameters for scale-up can be used for construction of economic pilot plant photobioreactors. The determination of light-dependent kinetics of growth and product formation is the first necessary step to achieve this. A wide variety of different parameters can be examined like the effect of different illumination conditions (light intensity, frequency of day/night cycles, flashing light, light color. . .) and thereby for each single application specific, relevant, and interesting parameters will be examined.