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1.
CO2 at different concentrations were added to cultures of the eukaryotic microalgae, Chlorella kessleri, C. vulgaris and Scenedesmus obliquus, and the prokaryotic cyanobacterium, Spirulina sp., growing in flasks and in a photobioreactor. In each case, the best kinetics and carbon fixation rate were with a vertical
tubular photobioreactor. Overall, Spirulina sp. had the highest rates. Spirulina sp., Sc. obliquus and C. vulgaris could grow with up to 18% CO2. 相似文献
2.
Morais MG Radmann EM Costa JA 《Zeitschrift für Naturforschung. C, Journal of biosciences》2011,66(5-6):313-318
Coal is the most abundant of the fossil fuels, with reserves estimated at 102 billions of tons. The feasibility of using coal as a fuel depends upon reducing emissions of gas when it is burnt, such as carbon dioxide (CO2), sulfur oxides (SO(x)), and nitrogen oxides (NO(x)). The removal of CO2 with microalgae may be one of the most efficient ways of reducing this gas, without the need for radical changes in the world's energy supply and production methods. Spirulina sp. LEB-18 and Scenedesmus obliquus LEB-22 were cultivated in serial tubular photobioreactors, with the aim of measuring the potential of CO2 biofixation and the resistance of the microalgae to SO2 and NO. Spirulina sp. and S. obliquus had CO2 biofixation scores of 0.27 and 0.22 g L(-1) d(-1), respectively. Both microalgae were resistant to SO2 and NO, and grew during the 15 d they were cultivated, which proves that using microalgae is an efficient method of biofixation of CO2 emitted when fossil fuels are burnt. 相似文献
3.
Marcelo Chuei Matsudo Raquel Pedrosa Bezerra Sunao Sato Attilio Converti Dr. João Carlos Monteiro de Carvalho 《Biotechnology journal》2012,7(11):1412-1417
Similar to other photosynthetic microorganisms, the cyanobacterium Arthrospira platensis can be used to produce pigments, single cell proteins, fatty acids (which can be used for bioenergy), food and feed supplements, and biofixation of CO2. Cultivation in a specifically designed tubular photobioreactor is suitable for photosynthetic biomass production, because the cultivation area can be reduced by distributing the microbial cells vertically, thus avoiding loss of ammonia and CO2. The aim of this study was to investigate the influence of light intensity and dilution rate on the photosynthetic efficiency and CO2 assimilation efficiency of A. platensis cultured in a tubular photobioreactor in a continuous process. Urea was used as a nitrogen source and CO2 as carbon source and for pH control. Steady‐state conditions were achieved in most of the runs, indicating that continuous cultivation of this cyanobacterium in a tubular photobioreactor could be an interesting alternative for the large‐scale fixation of CO2 to mitigate the greenhouse effect while producing high protein content biomass. 相似文献
4.
The effect of different flow rates (from 0.18 m∣s to 0.97 m∣s) on the productivity of Spirulina grown outdoors in a strongly curved tubular photobioreactor (CTP) was studied. The results were compared to those obtained
with a conventional photobioreactor made with straight tubes to form a loop (STP). The cultures were operated at a biomass
concentration of 10 g/l dry weight. The productivity of the culture increased by about 39% and 29% in the CTP and STP respectively
when the flow rate of the culture was increased from 0.18 m/s to 0.75 m/s. A further increase of the flow rate did not result
in any increase of the productivity in either of the photobioreactors. The better performance of the culture observed in the
CTP was attributed to an intermittent illumination pattern resulting from a secondary flow motion generated in the bends.
The power required for the induction of the same flow rate inside the two types of photobioreactor changed significantly.
At a Reynolds number of 4000, the power absorbed by the CTP was 25% higher than that required for water recycling in the STP
and rose by more than 40% at a Reynolds number of 20000.
Received: 3 July 1995 / Received revision: 16 October 1995 / Accepted: 24 October 1995 相似文献
5.
The biological photosynthetic process is useful and environmentally benign compared with other carbon dioxide (CO2) mitigation processes. In the present study, Anabaena sp. PCC 7120 was utilized for carbon dioxide mitigation. A customized airlift photobioreactor was found to provide higher light utilization efficiency and a higher rate of CO2 biofixation compared with that of a bubble column. The maximum biomass concentrations were 0.71 and 1.13 g L?1 in the bubble column and airlift photobioreactor, respectively, using BG110 medium under aerated conditions. A lower mixing time in the airlift photobioreactor compared with that of the bubble column resulted in improved mass transfer. The CO2 biofixation rate of Anabaena sp. PCC 7120 was determined using different phosphate concentrations at a light intensity of 120 μE m?2 s?1 and 5% (v/v) CO2-enriched air in the airlift photobioreactor. However, it was observed that the specific growth rate was independent at higher light intensity. In addition, it was observed that increased light intensity, phosphate and CO2 concentrations could enhance the CO2 biofixation efficiency to a greater extent. 相似文献
6.
Del Campo JA Rodríguez H Moreno J Vargas MA Rivas J Guerrero MG 《Journal of biotechnology》2001,85(3):289-295
The effect of dilution rate, mixing and daily solar cycles on lutein and biomass productivity of the green unicellular alga Muriellopsis sp. has been studied, throughout the year, in an outdoor tubular photobioreactor. Highest productivity values, for both lutein (about 180 mg m(-2) per day) and biomass (about 40 g (dry weight) m(-2) per day) were achieved on May and July. Values for the optimal dilution rate varied, being lower in May (0.06 h(-1)) than in November (0.09 h(-1)). Similar values for photosynthetic efficiency (about 4%) were recorded throughout the year, indicating that optimization of culture conditions was achieved for each experimental period. Along the daily solar cycle, there was a fast increase of lutein content of Muriellopsis sp. in response to irradiance during the early hours of daytime, with maximal lutein content (about 6 mg (g dry weight)(-1)) being recorded at noon, and decreasing slowly, thereafter. An increase in cell growth was observed following the establishment of maximum lutein/chlorophyll ratio, which might indicate a role for lutein in protecting cells from photodamage. 相似文献
7.
Factors Affecting Infection of Scenedesmus obliquus by a Chytridium sp. in Sewage Oxidation Ponds
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In a high-rate oxidation pond, 0.1 to 1.0% of the algal population of Scenedesmus obliquus was found to be infected by a chytrid. When suitable conditions developed, these infections burst into massive epidemics that killed most of the algae. The major factors triggering massive infections were optimal oxygen concentration and low concentrations of potassium and magnesium cations. The fungicide Benomyl was effective in preventing infection at a concentration of 1 mg/liter. 相似文献
8.
A mutant, MA-1, of Chlorococcum sp., grown in batch culture, produced about 54 mg ketocarotenoids/l with 10 mM nitrogen. The accumulation rate of these ketocarotenoids was independent of the nitrogen concentration under sunlight illumination. Fed-batch cultures showed poor growth and the average productivity of ketocarotenoids dropped from 2.6 mg/l day to 1.6 mg/l day in the two consecutive fed-batch runs. 相似文献
9.
Ferreira LS Rodrigues MS Converti A Sato S Carvalho JC 《Biotechnology and bioengineering》2012,109(2):444-450
Arthrospira platensis was cultivated in tubular photobioreactor in order to evaluate growth and biomass production at variable photosynthetic photon flux density (PPFD = 60, 120, and 240 μmol photons m(-2)s(-1)) and employing three different systems for cell circulation, specifically an airlift, a motor-driven pumping and a pressurized system. The influence of these two independents variables on the maximum cell concentration (X(m)), cell productivity (P(x)), nitrogen-to-cell conversion factor (Y(X/N) ), photosynthetic efficiency (PE), and biomass composition (total lipids and proteins), taken as responses, was evaluated by analysis of variance. The statistical analysis revealed that the best combination of responses' mean values (X(m) = 4,055 mg L(-1), P(x) = 406 mg L(-1)day(-1), Y(X/N) = 5.07 mg mg(-1), total lipids = 8.94%, total proteins = 30.3%, PE = 2.04%) was obtained at PPFD = 120 μmol photons m(-2)s(-1); therefore, this light intensity should be considered as the most well-suited for A. platensis cultivation in this photobioreactor configuration. The airlift system did not exert any significant positive statistical influence on the responses, which suggests that this traditional cell circulation system could successfully be substituted by the others tested in this work. 相似文献
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13.
Damien J. Farrelly Liam Brennan Colm D. Everard Kevin P. McDonnell 《Applied microbiology and biotechnology》2014,98(7):3157-3164
Bio-fixation of carbon dioxide (CO2) by microalgae has been recognised as an attractive approach to offset anthropogenic emissions. Biological carbon mitigation is the process whereby autotrophic organisms, such as microalgae, convert CO2 into organic carbon and O2 through photosynthesis; this process through respiration produces biomass. In this study Dunaliella tertiolecta was cultivated in a semicontinuous culture to investigate the carbon mitigation rate of the system. The algae were produced in 1.2-L Roux bottles with a working volume of 1 L while semicontinuous production commenced on day 4 of cultivation when the carbon mitigation rate was found to be at a maximum for D. tertiolecta. The reduction in CO2 between input and output gases was monitored to predict carbon fixation rates while biomass production and microalgal carbon content are used to calculate the actual carbon mitigation potential of D. tertiolecta. A renewal rate of 45 % of flask volume was utilised to maintain the culture in exponential growth with an average daily productivity of 0.07 g L?1 day?1. The results showed that 0.74 g L?1 of biomass could be achieved after 7 days of semicontinuous production while a total carbon mitigation of 0.37 g L?1 was achieved. This represented an increase of 0.18 g L?1 in carbon mitigation rate compared to batch production of D. tertiolecta over the same cultivation period. 相似文献
14.
The nucleotide sequences of a cytoplasmic and a chloroplast tRNATyr from Scenedesmus obliquus. 总被引:2,自引:0,他引:2
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The nucleotide sequences of two species of tyrosine accepting tRNA from the eukaryotic green alga Scenedesmus obliquus have been determined. The sequence of the cytoplasmic tRNATyr is: (sequence in text) This is the first chloroplast tRNATyr species to be sequenced. 相似文献
15.
Simultaneous nutrients and carbon removal during pretreated swine slurry degradation in a tubular biofilm photobioreactor 总被引:1,自引:0,他引:1
Ignacio de Godos Cristina González Eloy Becares Pedro A. García-Encina Raúl Muñoz 《Applied microbiology and biotechnology》2009,82(1):187-194
The biodegradation potential of an innovative enclosed tubular biofilm photobioreactor inoculated with a Chlorella sorokiniana strain and an acclimated activated sludge consortium was evaluated under continuous illumination and increasing pretreated
(centrifuged) swine slurry loading rates. This photobioreactor configuration provided simultaneous and efficient carbon, nitrogen,
and phosphorous treatment in a single-stage process at sustained nitrogen and phosphorous removals efficiencies ranging from
94% to 100% and 70–90%, respectively. Maximum total organic carbon (TOC), NH4
+, and PO4
3− removal rates of 80 ± 5 g C mr
−3 day−1, 89 ± 5 g N mr
−3 day−1, and 13 ± 3 g P mr
−3 day−1, respectively, were recorded at the highest swine slurry loadings (TOC of 1,247 ± 62 mg L−1, N–NH4
+ of 656 ± 37 mg L−1, P–PO4
3+ of 117 ± 19 mg L−1, and 7 days of hydraulic retention time). The unusual substrates diffusional pathways established within the phototrophic
biofilm (photosynthetic O2 and TOC/NH4
+ diffusing from opposite sides of the biofilm) allowed both the occurrence of a simultaneous denitrification/nitrification
process at the highest swine slurry loading rate and the protection of microalgae from any potential inhibitory effect mediated
by the combination of high pH and high NH3 concentrations. In addition, this biofilm-based photobioreactor supported efficient biomass retention (>92% of the biomass
generated during the pretreated swine slurry biodegradation). 相似文献
16.
Biodiesel production was examined with Scenedesmus obliquus in a recirculatory aquaculture system with fish pond discharge and poultry litter to couple with waste treatment. Lipid productivity of 14,400 liter ha(-1) year(-1) was projected with 11 cultivation cycles per year. The fuel properties of the biodiesel produced adhered to Indian and international standards. 相似文献
17.
In photobioreactors, which are usually operated under light limitation,sufficient dissolved inorganic carbon must be provided to avoid carbonlimitation. Efficient mass transfer of CO2 into the culture mediumisdesirable since undissolved CO2 is lost by outgassing. Mass transferof O2 out of the system is also an important consideration, due tothe need to remove photosynthetically-derived O2 before it reachesinhibitory concentrations. Hydrodynamics (mixing characteristics) are afunctionof reactor geometry and operating conditions (e.g. gas and liquid flow rates),and are a principal determinant of the light regime experienced by the culture.This in turn affects photosynthetic efficiency, productivity, and cellcomposition. This paper describes the mass transfer and hydrodynamics within anear-horizontal tubular photobioreactor. The volume, shape and velocity ofbubbles, gas hold-up, liquid velocity, slip velocity, axial dispersion,Reynoldsnumber, mixing time, and mass transfer coefficients were determined intapwater,seawater, and algal culture medium. Gas hold-up values resembled those ofvertical bubble columns, and the hydraulic regime could be characterized asplug-flow with medium dispersion. The maximum oxygen mass transfer coefficientis approximately 7 h–1. A regime analysisindicated that there are mass transfer limitations in this type ofphotobioreactor. A methodology is described to determine the mass transfercoefficients for O2 stripping and CO2 dissolution whichwould be required to achieve a desired biomass productivity. This procedure canassist in determining design modifications to achieve the desired mass transfercoefficient. 相似文献
18.
To optimize the aeration conditions for microalgal biomass production in a vertical flat-plate photobioreactor (VFPP), the effect of the aeration rate on biomass productivity was investigated under given conditions. Air enriched with 5% or 10% (v/v) CO(2) was supplied for the investigation at rates of 0.025-1 vvm. The CO(2) utilization efficiency, change of pH in the medium, and the optimum aeration rate were determined by evaluating biomass productivity. To investigate the VFPP mass transfer characteristics, the overall volumetric mass transfer coefficient, k(L)a, was evaluated for several different flat-plate sizes. Increasing the height of the VFPP could improve both the mass transfer of CO(2) and the illumination conditions, so this appeared to be a good method for scaling up. Based on a comparison of the k(L)a value at the optimum aeration rate with previously reported results, it was confirmed that the range of CO(2) concentration used in the experiments was cost-effective for mass culture. 相似文献
19.
尖状栅藻(Scenedesmus acuminatus(Lagerheim) Chodat)是一种高产油淡水单细胞绿藻,该藻在较低氮素浓度下能显著提高产油效率,是生产生物柴油的理想藻株。本研究以尖状栅藻为实验材料,通过测定藻细胞硝酸还原酶和Rubisco活性、碳氮元素含量和培养液硝酸根离子浓度,分析18.0、9.0、6.0、3.6 mmol·L-1初始氮浓度下尖状栅藻的碳氮同化特征和时相变化规律。结果显示,18.0 mmol·L-1组尖状栅藻细胞密度最高,为7.9×107 cells·mL-1,硝酸还原酶和Rubisco的活性高,且持续时间长。培养液中产生的NO2-随初始氮浓度的升高而增多,18.0 mmol·L-1组至培养期结束仍保持相对较高的NO2-水平。4个实验组(初始氮从高到低)培养10 d藻细胞的氮含量依次为7.2%、4.1%、2.8%和1.9% DW,碳含量为46%、52%、54.5%和57.4% DW,细胞的C/N摩尔比值为:8.0、16.7、24.3和35.2。研究结果表明初始氮浓度影响尖状栅藻的生长繁殖,藻细胞的碳氮同化相互影响,适宜的低氮浓度可促进藻细胞碳固定。 相似文献