RESUMO
The objective of this study was to cultivate Chlorella fusca LEB 111 with nanofibers indoors and outdoors to verify the effect on CO2 biofixation and macromolecule production. The microalgae were cultured with 10% (w v-1) polyacrylonitrile (PAN)/dimethylformamide (DMF) nanofibers containing 4% (w v-1) iron oxide nanoparticles (NPsFe2O3), which were added to the cultivations at concentrations of 0, 0.1, 0.3 and 0.5 g L-1. The CO2 biofixation was higher in outdoor assays (270.6 and 310.9 mg L-1 d-1) than in indoor assays (124.6 and 131 mg L-1 d-1) with 0.1 and 0.3 g L-1 nanofibers, respectively. The outdoor assays with 0.3 g L-1 nanofibers had 10.9% greater lipid production than the assays without nanofibers. Thus, this first study of outdoor cultivations with nanofibers as physical adsorbents of CO2 showed the effect of nanostructures in maximizing gas biofixation and producing biomolecules that can be used to obtain bioproducts.
Assuntos
Ciclo do Carbono , Dióxido de Carbono/metabolismo , Chlorella/fisiologia , Nanofibras/química , Polímeros/química , Biomassa , Concentração de Íons de Hidrogênio , Microalgas , TemperaturaRESUMO
The increase in the CO2 concentration in the Earth's atmosphere has been a topic of worldwide concern since anthropogenic emissions of greenhouse gases began increasing considerably during the industrial period. The effects of these mass emissions are probably the main cause of global warming, which has been observed over recent decades. Among the various techniques of CO2 capture, microalgal biofixation by photosynthesis is considered a promising technology due to the efficiency of these microorganisms in converting this gas into organic compounds through its use as a nutrient in the culture medium. Over the years, several research centers have developed studies on this subject, which have focused on mainly the development of bioreactors, the growth conditions that increase the efficiency of the process and the production of biomass with applicability in several areas. The biological mitigation of CO2 by microalgae has many advantages, including reductions in the concentration of an industrially sourced greenhouse gas and the energy or food obtained from the produced photosynthetic biomass. This versatility allows for the cultivation of economically useful biomass while reducing the environmental impacts of industrial facilities. In this context, this mini-review aims to discuss new technologies and strategies along with the main challenges and future prospects in the field and the ecological and economic impacts of CO2 biofixation by microalgae.
Assuntos
Ciclo do Carbono , Dióxido de Carbono/metabolismo , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Biomassa , Reatores Biológicos , Ecologia , Economia , Aquecimento Global , Gases de Efeito EstufaRESUMO
The objective of this study was to evaluate the biofixation and production of biocompounds by Chlorella fusca LEB 111 cultivated with different concentrations of carbon dioxide (CO2) adsorbent nanofibers in their free form or retained. Cultures were grown in 15% (vâ¯v-1) CO2 with 0.1, 0.3 and 0.5â¯gâ¯L-1 nanofibers developed with 10% (wâ¯v-1) polyacrylonitrile (PAN)/dimethylformamide (DMF), with or without nanoparticles; retained or not. The addition of 0.1â¯gâ¯L-1 nanofibers with nanoparticles in their free form to the cultures promoted the accumulation of approximately 3 times more carbon in the medium (46.6â¯mgâ¯L-1), a 45% higher biofixation rate (89.2â¯mgâ¯L-1â¯d-1) and increased carbohydrate production by approximately 2.3% (wâ¯w-1) of that observed in cultures grown without nanofibers. Therefore, nanofibers showed promising potential as physical adsorbents of CO2 in the cultivation to increase gas fixation and promote the synthesis of macromolecules.
Assuntos
Dióxido de Carbono/metabolismo , Chlorella/metabolismo , Substâncias Macromoleculares/metabolismo , Nanofibras , Carbono/metabolismoRESUMO
Fly ashes present several minerals that along with carbon dioxide (CO2) represent a promising nutrient source and an alternative to reduce environmental problems. Thus, the objective of this study was to investigate if CO2, thermoelectric fly ashes and reduction in nitrogen supply alters the production of macromolecules in Chlorella fusca LEB 111. For this purpose, 1.5 or 0.75â¯g L-1 of NaNO3, injection of 10% (v v-1) of CO2 as well as 0, 40 and 120â¯ppm of fly ashes were studied. The protein content was not impaired in cultivations with 0.75â¯gâ¯L-1 of NaNO3 since nitrogen was not fully consumed. Nevertheless, this cultivation strategy increased carbohydrate content by up to 25%, which could be fermented to produce bioethanol. Therefore, Chlorella fusca presented not only potential for CO2 biofixation and assimilation of nutrients from fly ashes but also for enhancement of carbohydrates accumulation when the nitrogen supply was reduced.
Assuntos
Dióxido de Carbono/metabolismo , Chlorella/metabolismo , Cinza de Carvão/metabolismo , Substâncias Macromoleculares/metabolismo , Nitrogênio/metabolismo , Biomassa , Metabolismo dos Carboidratos , CarboidratosRESUMO
This study aimed to use different conditions of magnetic field (MF) application during Chlorella fusca cultivation and evaluate CO2 biofixation by the microalga through growth kinetics in addition to the biomass composition. For this purpose, we tested different MF intensities applied for 1â¯hâ¯d-1 and for 24â¯h. Cultures exposed to the MF for 1â¯hâ¯d-1 (in both intensities) had greater biomass concentrations (1.42â¯g L-1) and 34% more productivity in the same time as the control assay. The biofixation rate increased by 50% with 60â¯mT for 1â¯hâ¯d-1, and the protein content was enhanced by 30â¯mT (56.21% w w-1). This study was the first to consider the MF effect on CO2 biofixation. MF applied for 1â¯hâ¯d-1 proved to be an efficient alternative method to increase the CO2 biofixation and growth of C. fusca besides to be an inexpensive and nontoxic method.
Assuntos
Dióxido de Carbono/metabolismo , Chlorella/metabolismo , Campos Magnéticos , Microalgas/metabolismo , Biomassa , CinéticaRESUMO
This study evaluated productivity, CO2 biofixation, and lipid content in biomass of the acidophilic microalga Chlamydomonas acidophila LAFIC-004 cultivated with five different carbon dioxide concentrations. The influence of carbon dioxide concentration on nutrient removal and pH was also investigated. Treated wastewater (secondary effluent) was used as culture medium. Five experimental setups were tested: T-0% - injection of atmospheric air (0.038% CO2), T-5% (5% CO2), T-10% (10% CO2), T-15% (15% CO2) and T-20% (20% CO2). The T-5% and T-10% experiments showed the highest values of productivity and CO2 biofixation, and maximum biomass dry weight was 0.48 ± 0.02 and 0.51 ± 0.03â gâ L-1, respectively. This acidophilic microalga proved to be suitable for carbon biofixation and removal of nutrients from secondary effluent of wastewater treatment plants with high CO2 concentration. All assays were performed without pH control. This microalga species presented high lipid content. However, fatty acid methyl esters (FAME) are not suitable for biodiesel use.
Assuntos
Microalgas , Águas Residuárias , Biomassa , Dióxido de Carbono , LipídeosRESUMO
The aim of this work was to evaluate if the addition of the chemical absorbents diethanolamine and potassium carbonate affects the CO2 biofixation, growth and biomass composition of Spirulina sp. LEB 18. The association of the diethanolamine (DEA) and potassium carbonate (K2CO3) absorbents increased the dissolved inorganic carbon concentration in the cultivation medium, allowing greater CO2 biofixation by the Spirulina. Higher biomass concentration (2.1â¯gâ¯L-1) and maximum productivity (174.2â¯mgâ¯L-1â¯d-1) were observed with the mixture of 1.64â¯mmolâ¯L-1 of DEA and 0.41â¯mmolâ¯L-1 of K2CO3. In this cultivation condition, Spirulina sp. LEB 18 showed high protein content (58.8â¯wâ¯w-1) and an increased carbohydrate concentration (23.7%â¯wâ¯w-1). The addition of these absorbent concentrations may be applied in the cultivation of Spirulina sp. LEB 18 to increase CO2 biofixation and cell growth.
Assuntos
Dióxido de Carbono/metabolismo , Spirulina , Biomassa , Carbonatos/química , Etanolaminas/química , Potássio/químicaRESUMO
Microalgae are among the most productive biological systems for converting sunlight into chemical energy, which is used to capture and transform inorganic carbon into biomass. The efficiency of carbon dioxide capture depends on the cultivation system configuration (photobioreactors or open systems) and can vary according to the state of the algal physiology, the chemical composition of the nutrient medium, and environmental factors such as irradiance, temperature and pH. This mini-review is focused on some of the most important environmental factors determining photosynthetic activity, carbon dioxide biofixation, cell growth rate and biomass productivity by microalgae. These include carbon dioxide and O2 concentrations, light intensity, cultivation temperature and nutrients. Finally, a review of the operation of microalgal cultivation systems outdoors is presented as an example of the impact of environmental conditions on biomass productivity and carbon dioxide fixation.
Assuntos
Reatores Biológicos , Dióxido de Carbono/metabolismo , Meio Ambiente , Microalgas/metabolismo , Concentração de Íons de Hidrogênio , Luz , Microalgas/crescimento & desenvolvimento , Microalgas/fisiologia , Nutrientes/metabolismo , Oxigênio/metabolismo , Fotossíntese , TemperaturaRESUMO
CO2 emissions and the large quantity of lignocellulosic waste generated by industrialized nations constitute problems that may affect human health as well as the global economy. The objective of this work was to evaluate the effects of using CO2 and pentoses on the growth, protein profile, carbohydrate content and potential ethanol production by fermentation of Chlorella minutissima biomass. CO2 and pentose supplementation can induce changes in the microalgal protein profile. A biomass production of 1.84g.L-1 and a CO2 biofixation rate of 274.63mg.L-1.d-1 were obtained with the use of 20% (v.v-1) CO2. For cultures with 20% (v.v-1) CO2 and reduced nitrogen, the carbohydrate content was 52.3% (w.w-1), and theoretically, 33.9mL.100g-1 of ethanol can be produced. These results demonstrate that C. minutissima cultured with the combined use of CO2 and pentoses generates a biomass with high bioenergetic potential.
Assuntos
Dióxido de Carbono , Chlorella , Pentoses , Biomassa , Humanos , MicroalgasRESUMO
This study evaluated the intermittent addition of coal flue gas wastes (CO2, SO2, NO and ash) into a Synechococcus nidulans LEB 115 cultivation in terms of growth parameters, CO2 biofixation and biomass characterization. The microalga from a coal thermoelectric plant showed tolerance up to 200ppm SO2 and NO, with a maximum specific growth rate of 0.18±0.03d-1. The addition of thermal coal ash to the cultivation increased the Synechococcus nidulans LEB 115 maximum cell growth by approximately 1.3 times. The best CO2 biofixation efficiency was obtained with 10% CO2, 60ppm SO2, 100ppm NO and 40ppm ash (55.0±3.1%). The biomass compositions in the assays were similar, with approximately 9.8% carbohydrates, 13.5% lipids and 62.7% proteins.
Assuntos
Dióxido de Carbono , Centrais Elétricas , Synechococcus , Poluição do Ar/prevenção & controle , Biomassa , Carvão MineralRESUMO
CO2 biofixation by microalgae and cyanobacteria is an environmentally sustainable way to mitigate coal burn gas emissions. In this work the microalga Chlorella fusca LEB 111 and the cyanobacteria Spirulina sp. LEB 18 were cultivated using CO2 from coal flue gas as a carbon source. The intermittent flue gas injection in the cultures enable the cells growth and CO2 biofixation by these microorganisms. The Chlorella fusca isolated from a coal power plant could fix 2.6 times more CO2 than Spirulina sp. The maximum daily CO2 from coal flue gas biofixation was obtained with Chlorella fusca (360.12±0.27mgL-1d-1), showing a specific growth rate of 0.17±<0.01d-1. The results demonstrated the Chlorella fusca LEB 111 and Spirulina sp. LEB 18 potential to fix CO2 from coal flue gas, and sequential biomass production with different biotechnological destinations.
Assuntos
Poluentes Atmosféricos/metabolismo , Dióxido de Carbono/metabolismo , Chlorella/metabolismo , Microalgas/metabolismo , Spirulina/metabolismo , Poluentes Atmosféricos/análise , Biodegradação Ambiental , Biotecnologia , Dióxido de Carbono/análise , Chlorella/crescimento & desenvolvimento , Carvão Mineral , Microalgas/crescimento & desenvolvimento , Centrais Elétricas , Spirulina/crescimento & desenvolvimentoRESUMO
Microalgae can use the CO2 from coal power plants in their metabolic pathways. However, these microorganisms must be able to tolerate other residues produced from burning coal. This study evaluated the wastes addition (CO2, SO2, NO and ash) present in the flue gas from a coal power plant on the growth parameters during culture, CO2 biofixation and on the biomass characterization of Chlorella fusca LEB 111. The SO2 and NO injection (until 400ppm) in cultivations did not markedly affect CO2 biofixation by microalga. The best CO2 biofixation efficiency was obtained with 10% CO2, 200ppm SO2 and NO and 40ppm ash (50.0±0.8%, w w(-1)), showing a specific growth rate of 0.18±0.01 d(-1). The C. fusca LEB 111 biomass composition was similar in all experiments with around 19.7% (w w(-1)) carbohydrates, 15.5% (w w(-1)) lipids and 50.2% (w w(-1)) proteins.