Optimization of biomass, vitamins, and carotenoid yield on light energy in a flat-panel reactor using the A-stat technique.
TL;DR: It is concluded that it is advantageous to use the A-stat instead of chemostats to determine culture characteristics and optimize a specific photobioreactor.
Abstract: Acceleration-stat (A-stat) cultivations in which the dilution rate is continuously changed at a constant acceleration rate, leading to different average light intensities inside the photobioreactor, can supply more information and reduce experimental time compared with chemostat cultivations. The A-stat was used to optimize the biomass and product yield of continuous cultures of the microalgae D. tertiolecta in a flat-panel reactor. In this study, four different accelerations were studied, a pseudo steady state was maintained at acceleration rates of 0.00016 and 0.00029 h-2 and results were similar to those of the chemostat. An increase in the acceleration rate led to an increase in the deviation between results obtained in the A-stat and in the chemostats. We concluded that it is advantageous to use the A-stat instead of chemostats to determine culture characteristics and optimize a specific photobioreactor. The effect of average light intensity inside the photobioreactor on the production of vitamins C and E, lutein, and β-carotene was studied using the A-stat. The highest concentrations of these products were 3.48 ± 0.46, 0.33 ± 0.06, 5.65 ± 0.24, and 2.36 ± 0.38 mg g-1 respectively. These results were obtained at different average light intensities, showing the importance of optimizing each product on light intensity. © 2004 Wiley Periodicals, Inc.
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TL;DR: This article presents a critical review, focusing on various microalgae species that consume CO2 and nutrients from wastewater, and provide high quality biofuel.
Abstract: Algae have recently received growing attention given its prospects as a source of renewable energy and its potential for CO2 capture. Algae culture is of increasing value given that: (i) algae can be cultivated on non-agricultural land using wastewater, (ii) algae can provide a high yield on a per unit of light irradiated area, (iii) algae growth requires CO2 and nutrients that can be obtained from wastewater and fossil fuel combustion and (iv) algae contains high oil and starch making possible the production of high quality biodiesel. Thus, algae culture can contribute to CO2 fixation, wastewater treatment and can be a source of bioenergy. This article presents a critical review, focusing on various microalgae species that consume CO2 and nutrients from wastewater, and provide high quality biofuel. In this respect, a number of relevant topics are discussed in this review: (a) the media for algae culture, (b) the photobioreactor, (c) the associated wastewater treatment processes, (d) the CO2 capture mechanism and (e) microalgal harvesting. This review also considers various aspects of the biomass processing such as (a) lipid extraction, (b) thermodynamics of the produced biomass conversion, (c) biomass gasification, (d) biodiesel production, (e) catalysts, (f) reaction pathways/mechanisms and (g) reaction kinetics.
494 citations
TL;DR: The present paper deals with the photobioreactors of different geometry available for biomass production and focuses on the hybrid types of reactors (integrating two reactors) which can be used for overcoming the bottlenecks of a single Photobioreactor.
469 citations
Cites background or methods from "Optimization of biomass, vitamins, ..."
...The reactor was illuminated at one surface with 10 fluorescent tubes having total light intensity of approximately 1000 lmol photons m 2 s 1 (Barbosa et al., 2005)....
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...…et al., 2001 Phaeodactylum tricornutum Continuous Helical tubular 75 – 1.4 Hall et al., 2003 Dunaliella tertiolecta Continuous Flat panel 3.4 2.46 – Barbosa et al., 2005 Nanochloropsis Continuous Flat panel 440 – 0.27 Cheng-Wu et al., 2001 Haematococcus pluvialis Continuous Tubular 25,000…...
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...A flat panel was built up by Barbosa et al. (2005) from lexan (polycarbonate) held together in stainless steel having surface to volume ratio of 0.34 cm 1....
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TL;DR: This review discusses microalgae used to produce biological substances and its economic importance in food science, the pharmaceutical industry and public health.
467 citations
TL;DR: The salient features, limitations of developed photobioreactors and recent developments in the field of photobiOREactors are covered.
Abstract: Microalgal species are recently in the spotlight for biofuels production like biodiesel, bioethanol and biohydrogen. Algae are also used as a biofertiliser, source of nutrient and for controlling pollution. Algae being a photosynthetic organism are produced in the photo bioreactors. Hence the design and development of photobioreactors for maximum production of algae is very important. Apart from maximum production, other factors such as design, cost effectiveness of the bioreactor, purity of the algae produced, user friendly, low maintenance and space convenience need to be optimized. The bioreactors which are used for the purpose of growing algae are bubble column photobioreactor, airlift photo bioreactor, flat panel bioreactor, horizontal tubular photobioreactor, stirred tank photobioreactor etc. These bioreactors have their own advantages and disadvantages. Work is on for developing hybrid type of bioreactors which may overcome the limitations of the developed photobioreactors. This paper covers the salient features, limitations of developed photobioreactors and recent developments in the field of photobioreactors.
456 citations
TL;DR: In this paper, the authors present a state-of-the-art review on the process effect, especially on the effects of photobiochemical process, micro algal species, physicochemical process and hydrodynamic process on the performance of microalgal-CO2 fixation and biomass production.
Abstract: Global warming caused by anthropogenic CO2 emission has been one of the most important issues in the fields of science, environment and even international economics and politics. To control and reduce CO2 emissions, intensive carbon dioxide capture and storage (CCS) technologies have been comprehensively developed for sequestration of CO2 especially from combustion flue gas. Microalgae-based CO2 biological fixation is regarded as a potential way to not only reduce CO2 emission but also achieve energy utilization of microalgal biomass. However, in this approach culture process of microalgae plays an important role as it is directly related to the mechanism of microalgal-CO2 fixation and characteristics of microalgal biomass production. The aim of this work is to present a state-of-the-art review on the process effect, especially on the effects of photobiochemical process, microalgal species, physicochemical process and hydrodynamic process on the performance of microalgal-CO2 fixation and biomass production. Also, the perspectives are proposed in order to provide a positive reference on developing its fundamental research and key technology.
338 citations
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688 citations
TL;DR: It is deduced that high photosynthetic efficiencies, 15% on a PAR-basis, can be achieved and a new photobioreactor design is proposed in which light capture is physically separated from photoautotrophic cultivation.
Abstract: Enclosed outdoor photobioreactors need to be developed and designed for large-scale production of phototrophic microorganisms. Both light regime and photosynthetic efficiency were analyzed in characteristic examples of state-of-the-art pilot-scale photobioreactors. In this study it is shown that productivity of photobioreactors is determined by the light regime inside the bioreactors. In addition to light regime, oxygen accumulation and shear stress limit productivity in certain designs. In short light-path systems, high efficiencies, 10% to 20% based on photosynthetic active radiation (PAR 400 to 700 nm), can be reached at high biomass concentrations (>5 kg [dry weight] m(-3)). It is demonstrated, however, that these and other photobioreactor designs are poorly scalable (maximal unit size 0.1 to 10 m(3)), and/or not applicable for cultivation of monocultures. This is why a new photobioreactor design is proposed in which light capture is physically separated from photoautotrophic cultivation. This system can possibly be scaled to larger unit sizes, 10 to >100 m(3), and the reactor liquid as a whole is mixed and aerated. It is deduced that high photosynthetic efficiencies, 15% on a PAR-basis, can be achieved. Future designs from optical engineers should be used to collect, concentrate, and transport sunlight, followed by redistribution in a large-scale photobioreactor.
476 citations
TL;DR: Thermally labile azo-initiators used to generate peroxyl radicals at a known, steady rate in an aqueous dispersion of dilinoleoylphosphatidylcholine multilamellar liposomes are used to study the antioxidant behaviour of asCorbate itself and ascorbate in combination with a water-soluble alpha-tocopherol analogue (TROLOX(-].
409 citations
TL;DR: The possibility of a cooperative interaction between fat-soluble antioxidants is examined in a membrane model in this article, where a combination of beta-carotene and alpha-tocopherol results in an inhibition of lipid peroxidation significantly greater than the sum of individual inhibitions.
407 citations