Photosynthetic efficiency optimization studies with the macroalga Gracilaria tikvihae: Implications for CO2 emission control from power plants

Laws, Edward A.; Berning, J.L.

doi:10.1016/0960-8524(91)90108-v

Cited by 21 publications

(9 citation statements)

References 10 publications

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“…(1) and (2): 2 and O 2 molar fractions in the inlet and outlet gas phases, P 0 is the atmospheric pressure (Pa), P 1 is the pressure of the inlet gas, F air is the gas flow rate (m 3 h -1 ), M wCO 2 and M wO 2 are the molecular weights of CO 2 and O 2 (g mol -1 ), T is the ambient absolute temperature (K) and V culture is the volume of the culture medium (L).…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, a reliable, effective and renewable air cleaning system is strongly desired. One approach to make such a system is to utilize microalgae, a photoautotropic microorganism, which has been proven to be a natural source of high-value compounds for the pharmaceutical and food industries [1][2][3]. CO 2 is removed by microalgae through photosynthesis, while oxygen is produced simultaneously, and one is also able to supply food via the choice of microalgae species within edible biomass [4].…”

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confidence: 99%

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Optimization of Carbon Dioxide Fixation by Chlorella vulgaris Cultivated in a Membrane‐Photobioreactor

et al. 2007

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In this paper, an enclosed membrane-photobioreactor was designed to remove CO 2 using Chlorella vulgaris. The performances of four reactors, which included the presented novel bioreactor, a draft tube airlift photobioreactor, a bubble column and a membrane contactor, were compared. The effects of the gas flow rate, light intensity, quality of the inner light source, and the characteristics of membrane module on CO 2 fixation were investigated. The results showed that the rate of CO 2 fixation in the membrane-photobioreactor was 0.95-5.40 times higher than that in the other three conventional reactors under the optimal operating conditions IntroductionThe CO 2 concentration of the environment is of great importance to worldwide health. The optimal CO 2 concentration for human beings is ca. 0.04 %. Higher concentration may cause headaches, tinnitus and elevated blood pressure. Therefore, the concentration range of CO 2 in isolated environments such as a space station or a submarine must normally be strictly controlled to be less than 0.5 %.Physicochemical absorbents are widely used for CO 2 removal at present. These materials, e.g., LiOH, are normally non-renewable, and thus, routine replenishment is required and significant extra space is necessary for their storage. Therefore, a reliable, effective and renewable air cleaning system is strongly desired. One approach to make such a system is to utilize microalgae, a photoautotropic microorganism, which has been proven to be a natural source of high-value compounds for the pharmaceutical and food industries [1][2][3]. CO 2 is removed by microalgae through photosynthesis, while oxygen is produced simultaneously, and one is also able to supply food via the choice of microalgae species within edible biomass [4].The process of CO 2 fixation in a microalgal cultivation system, commonly a photobioreactor, is complicated by the effects of cellular metabolism, irradiance distribution and gas-liquid mass transfer. Chlorella vulgaris (C. vulgaris), one of the edible green algae, has been considered to be very suitable for CO 2 biological fixation, since it has a good photosynthetic capacity, high reproduction rate and is easy to utilize in engineering systems [5][6][7]. However, due to the severe cellular self-shading effects, especially with dense culturing and strong external irradiance, a large dark zone in the center and a small highly illuminated zone near the surface coexist in a photobioreactor, neither of which is appropriate for the cell's growth [8]. Thus, a lot of attention is being given to light availability for the design of a photoreactor with the aim of increasing the mass or metabolite productivity [9][10][11][12]. However, the effect of gas-liquid mass transfer is usually disregarded since CO 2 removal is not the main purpose in most studies of microalgae cultivation.Based on previous research by the current authors [13][14][15], a membrane-photobioreactor with a hollow fiber membrane module integrated inside, was designed to remove CO 2 with C. vulgaris in...

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

Optimization of Carbon Dioxide Fixation by Chlorella vulgaris Cultivated in a Membrane‐Photobioreactor

et al. 2007

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“…Plants use solar energy to perform photosynthesis, but the efficiency of energy transformation is low at the cost of supporting their lives. Even under the optimal artificial conditions, energy efficiency can only reach about 7% in macroalga under full sunlight [1].…”

Section: Introductionmentioning

confidence: 99%

“…Equation 1 gives an example of the overall photoreduction of CO 2 to methanol. Based on thermodynamics, converting one mole of CO 2 into methanol requires 228 kJ (DH) of energy at 298 K. Furthermore, the Gibbs free energy of Eq.…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic Reduction of Greenhouse Gas CO2 to Fuel

2009

Catal Surv Asia

137

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Sun is the Earth's ultimate and inexhaustible energy source. One of the best routes to remedy the CO 2 problem is to convert it to valuable hydrocarbons using solar energy. In this study, CO 2 was photocatalytically reduced to produce methanol, methane and ethylene in a steady-state optical-fiber reactor under artificial light and real sunlight irradiation. The photocatalyst was dip-coated on the optical fibers that enable the light to transmit and spread uniformly inside the reactor. The optical-fiber photoreactor, comprised of nearly 120 photocatalyst-coated fibers, was designed and assembled. The XRD spectra indicated the anatase phase for all photocatalysts. It is found that the methanol yield increased with UV light intensity. A maximum methanol yield of 4.12 lmole/g-cat h is obtained when 1.0 wt% Ag/TiO 2 photocatalyst was used under a light intensity of 10 W/cm 2 . When mixed oxide, TiO 2 -SiO 2 , is doped with Cu and Fe metals, the resulting photocatalysts show substantial difference in hydrocarbon production as well as product selectivity. Methane and ethylene were produced on Cu-Fe loaded TiO 2 -SiO 2 photocatalyst. Since dye-sensitized Cu-Fe/P25 photocatalyst can fully harvest the light energy of 400-800 nm from sunlight, its photoactivity was significantly enhanced. Finally, CO 2 photoreduction was studied by in situ IR spectroscopy and possible mechanism for the photoreaction was proposed.

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“…Such environmental predictions suggest that a doubled atmospheric CO 2 concentration by the mid-end of this twenty-first century will bring a proportional increase of dissolved CO 2 (together with a slight decrease of pH and marginal increases of HCO 3 − ) at the ocean surface (Stumm and Morgan 1981;Raven and Falkowski 1999), affecting the photosynthetic control of CO 2 levels (Bowes 1993;Gao et al 1993). This fact, closely related with the increase of coastal activities which produce important amounts of wastes, including inorganic nutrients (Troell et al 2003), makes micro-and macroalgae interesting organisms to predict possible impacts (Beardall et al 1998;Raven and Falkowski 1999), responses (Johnston and Raven 1990;Beer and Koch 1996;Kübler et al 1999;Andría et al 2001;Collins and Bell 2004), and remediation processes by considering biomass production through cultivation techniques (Laws and Berning 1991;Gao et al 1991Gao et al , 1993Gao and McKinley 1994;Keffer and Kleinheinz 2002;Doucha et al 2005;Israel et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Effects of increased CO2 levels on growth, photosynthesis, ammonium uptake and cell composition in the macroalga Hypnea spinella (Gigartinales, Rhodophyta)

2011

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The red seaweed Hypnea spinella (Gigartinales, Rhodophyta), was cultured at laboratory scale under three different CO 2 conditions, non-enriched air (360 ppm CO 2 ) and CO 2 -enriched air at two final concentrations (750 and 1,600 ppm CO 2 ), in order to evaluate the influence of increased CO 2 concentrations on growth, photosynthetic capacity, nitrogen removal efficiency, and chemical cellular composition. Average specific growth rates of H. spinella treated with 750 and 1,600 ppm CO 2 -enriched air increased by 85.6% and 63.2% compared with non-enriched air cultures. CO 2 reduction percentages close to 12% were measured at 750 ppm CO 2 with respect to 5% and 7% for cultures treated with air and 1,600 ppm CO 2 , respectively. Maximum photosynthetic rates were enhanced significantly for high CO 2 treatments, showing P max values 1.5-fold higher than that for air-treated cultures. N-NH 4 + consumption rates were also faster for algae growing at 750 and 1,600 ppm CO 2 than that for non-enriched air cultures. As a consequence of these experimental conditions, soluble carbohydrates increased and soluble protein contents decreased in algae treated with CO 2 -enriched air. However, internal C and N contents remained constant at the different CO 2 concentrations. No significant differences in data obtained with both elevated CO 2 treatments, under the assayed conditions, indicate that H. spinella is saturated at dissolved inorganic carbon concentrations close by twice the actual atmospheric levels. The results show that increased CO 2 concentrations might be considered a key factor in order to improve intensively cultured H. spinella production yields and carbon and nitrogen bioremediation efficiencies.

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Photosynthetic efficiency optimization studies with the macroalga Gracilaria tikvihae: Implications for CO2 emission control from power plants

Cited by 21 publications

References 10 publications

Optimization of Carbon Dioxide Fixation by Chlorella vulgaris Cultivated in a Membrane‐Photobioreactor

Optimization of Carbon Dioxide Fixation by Chlorella vulgaris Cultivated in a Membrane‐Photobioreactor

Photocatalytic Reduction of Greenhouse Gas CO2 to Fuel

Effects of increased CO2 levels on growth, photosynthesis, ammonium uptake and cell composition in the macroalga Hypnea spinella (Gigartinales, Rhodophyta)

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