The production of biofuels is currently presented as a possible answer in the search for sustainable alternatives for the total or partial substitution of fossil fuels. One of the most successful biofuels that have be...The production of biofuels is currently presented as a possible answer in the search for sustainable alternatives for the total or partial substitution of fossil fuels. One of the most successful biofuels that have been developed is bioethanol. However, bioethanol production has been limited since it relies on the use of sugar cane or cereals. These materials are important sources of food and their demand as both a biofuel and a foodstuff has led to the price increase and may lead to possible shortages. Our group has focused on searching for native microalgae as sources of carbohydrates and bioethanol, with the goal of finding a sustainable source of bioethanol. Currently, twelve different strains which reach growth rates between 0.7 - 1.8 g/L and present carbohydrate production under osmotic shock conditions have been isolated. In this work, we demonstrate the results obtained with the Chlorella sp. [1] strain and the results obtained with the Scenedesmus sp. strain. The Scenedesmus sp. strain showed an increase in the production from 22 to 650 mg/sugar/g of biomass (dry weight), after 24 hours of osmotic shock with 0.1 M NaCl. The osmolytes which were produced after osmotic shock were identified as sucrose and trehalose, both of which are fermentable. These results demonstrate that this strain, through the photosynthetic pathway and osmotic shock, is a potential source of fermentable sugars.展开更多
In this study,the evaluation of the performance of the split internal loop photobioreactor for culturing a species of green microalgae,Scenedesmus sp.under different operating superficial gas velocity and during a dif...In this study,the evaluation of the performance of the split internal loop photobioreactor for culturing a species of green microalgae,Scenedesmus sp.under different operating superficial gas velocity and during a different time of growth(i.e.,starting for the first day until end day of the culturing process)was addressed.The evaluation of the performance of the split internal loop photobioreactor was included assessing the density,pH,temperature,viscosity,surface tension,the optical density,cell population,dry biomass,and chlorophyll of the culture medium of the microalgae culturing.Additionally,the hydrodynamics of a Split Internal-Loop Photobioreactor with microalgae culturing was comprehensively quantified.Radioactive particle tracking(RPT)and gamma-ray computed tomography(CT)techniques were applied for the first time to quantify and address the influence of microalgae culture on the hydrodynamic parameters.The hydrodynamics parameters such as local liquid velocity field,shear stresses,turbulent kinetic energy,and local gas holdup profiles were measured at different superficial gas velocities as well as under different times of algae growth.The obtained results indicate that the flow distribution may significantly affect the performance of the photobioreactor,which may have substantial effects on the cultivation process.The obtained experimental data can serve as benchmark data for the evaluation and validation of computational fluid dynamics(CFD)codes and their closures.This,in turn,allows us to develop efficient reactors and consequently improving the productivity and selectivity of these photobioreactors.展开更多
Sixteen Scenedesmus species or strains have been employed to investigate the maximum capacity of nickel (Ni) accumulation in 10 mg/L Ni solution. The results showed that the capacity of accumulating Ni from aqueou...Sixteen Scenedesmus species or strains have been employed to investigate the maximum capacity of nickel (Ni) accumulation in 10 mg/L Ni solution. The results showed that the capacity of accumulating Ni from aqueous solution in 16 Scenedesmus species or strains showed the diversity. S. quadricauda freshwater algae culture collection of the Institute of Hydrobiology (FACHB) 44 and S. quadricauda FACHB 506 performed much more capacity of Ni accumulation than other species such as Scenedesmus sp. FACHB 416 and Scenedesmus sp. FACHB 489. Sequestration of Ni ions from aqueous solution was very efficient (26.7 mg Ni/g dry weight, in the 100 mg/L Ni solution) in S. quadricauda FACHB 44. The kinetics of Ni binding indicated that Ni bioaccumulation, in algal cell of S. quadricauda FACHB 44, possessed a rapid biosorption (5 min) and an slow bioaccumulation (2-3 h). More than 70% of Ni binding in algal cell were accumulated by biosorption and the remaining 20%-30% were bioaccumulated by energy_consumed transportation. It is much more higher ratio of energy_consumed transportation in S. quadricauda FACHB 44 than in other algae. Both the transmission electron microscope (TEM) and the energy_dispersive X_ray (EDX) microanalyses also revealed the different mechanisms of bioaccumulation in the various subcellular regions: a very fast adsorption in the cell wall; and a time_dependent absorption in protoplasm, specially in starch and chromatin.展开更多
基金Funding by Instituto Politecnico Nacional PIFI-20100242.
文摘The production of biofuels is currently presented as a possible answer in the search for sustainable alternatives for the total or partial substitution of fossil fuels. One of the most successful biofuels that have been developed is bioethanol. However, bioethanol production has been limited since it relies on the use of sugar cane or cereals. These materials are important sources of food and their demand as both a biofuel and a foodstuff has led to the price increase and may lead to possible shortages. Our group has focused on searching for native microalgae as sources of carbohydrates and bioethanol, with the goal of finding a sustainable source of bioethanol. Currently, twelve different strains which reach growth rates between 0.7 - 1.8 g/L and present carbohydrate production under osmotic shock conditions have been isolated. In this work, we demonstrate the results obtained with the Chlorella sp. [1] strain and the results obtained with the Scenedesmus sp. strain. The Scenedesmus sp. strain showed an increase in the production from 22 to 650 mg/sugar/g of biomass (dry weight), after 24 hours of osmotic shock with 0.1 M NaCl. The osmolytes which were produced after osmotic shock were identified as sucrose and trehalose, both of which are fermentable. These results demonstrate that this strain, through the photosynthetic pathway and osmotic shock, is a potential source of fermentable sugars.
基金The authors would like to acknowledge the financial aid provided by the Iraqi government,the Ministry of Higher Education Iraq,and the Higher Committee for Education Development in Iraq(HCED)and the fund provided by Missouri S&T.
文摘In this study,the evaluation of the performance of the split internal loop photobioreactor for culturing a species of green microalgae,Scenedesmus sp.under different operating superficial gas velocity and during a different time of growth(i.e.,starting for the first day until end day of the culturing process)was addressed.The evaluation of the performance of the split internal loop photobioreactor was included assessing the density,pH,temperature,viscosity,surface tension,the optical density,cell population,dry biomass,and chlorophyll of the culture medium of the microalgae culturing.Additionally,the hydrodynamics of a Split Internal-Loop Photobioreactor with microalgae culturing was comprehensively quantified.Radioactive particle tracking(RPT)and gamma-ray computed tomography(CT)techniques were applied for the first time to quantify and address the influence of microalgae culture on the hydrodynamic parameters.The hydrodynamics parameters such as local liquid velocity field,shear stresses,turbulent kinetic energy,and local gas holdup profiles were measured at different superficial gas velocities as well as under different times of algae growth.The obtained results indicate that the flow distribution may significantly affect the performance of the photobioreactor,which may have substantial effects on the cultivation process.The obtained experimental data can serve as benchmark data for the evaluation and validation of computational fluid dynamics(CFD)codes and their closures.This,in turn,allows us to develop efficient reactors and consequently improving the productivity and selectivity of these photobioreactors.
文摘Sixteen Scenedesmus species or strains have been employed to investigate the maximum capacity of nickel (Ni) accumulation in 10 mg/L Ni solution. The results showed that the capacity of accumulating Ni from aqueous solution in 16 Scenedesmus species or strains showed the diversity. S. quadricauda freshwater algae culture collection of the Institute of Hydrobiology (FACHB) 44 and S. quadricauda FACHB 506 performed much more capacity of Ni accumulation than other species such as Scenedesmus sp. FACHB 416 and Scenedesmus sp. FACHB 489. Sequestration of Ni ions from aqueous solution was very efficient (26.7 mg Ni/g dry weight, in the 100 mg/L Ni solution) in S. quadricauda FACHB 44. The kinetics of Ni binding indicated that Ni bioaccumulation, in algal cell of S. quadricauda FACHB 44, possessed a rapid biosorption (5 min) and an slow bioaccumulation (2-3 h). More than 70% of Ni binding in algal cell were accumulated by biosorption and the remaining 20%-30% were bioaccumulated by energy_consumed transportation. It is much more higher ratio of energy_consumed transportation in S. quadricauda FACHB 44 than in other algae. Both the transmission electron microscope (TEM) and the energy_dispersive X_ray (EDX) microanalyses also revealed the different mechanisms of bioaccumulation in the various subcellular regions: a very fast adsorption in the cell wall; and a time_dependent absorption in protoplasm, specially in starch and chromatin.
