Produced water(PW)from oil and gas exploration adversely affects aquatic life and living organisms,necessitating treatment before discharge to meet effluent permissible limits.This study first used activated sludge to...Produced water(PW)from oil and gas exploration adversely affects aquatic life and living organisms,necessitating treatment before discharge to meet effluent permissible limits.This study first used activated sludge to pretreat PW in a sequential batch reactor(SBR).The pretreated PW then entered a 13 L photobioreactor(PBR)containing Scenedesmus obliquus microalgae culture.Initially,10%of the PW mixed with 90%microalgae culture in the PBR.After the exponential growth of the microalgae,an additional 25%of PW was added to the PBR without extra nutrients.This study reported the growth performance of microalgae in the PBR as well as the reduction in effluent’s total organic carbon(TOC),total dissolved solids(TDS),electrical conductivity(EC),and heavy metals content.The results demonstrated removal efficiencies of 64%for TOC,49.8%for TDS,and 49.1%for EC.The results also showed reductions in barium,iron,and manganese in the effluent by 95,76,and 52%,respectively.展开更多
[Objective] The paper aims to provide references to cultivate I.galbana in a large scale and explore its medical value.[Method] I.galbana had been cultivated in different light-path flat plate bioreactors,and the grow...[Objective] The paper aims to provide references to cultivate I.galbana in a large scale and explore its medical value.[Method] I.galbana had been cultivated in different light-path flat plate bioreactors,and the growth condition and content of organic matter within cells of I.galbana had been analyzed.[Result] Growth rate and volumetric productivity of I.galbana cells increased as light-path of flat plate bioreactors decreased,however,daily areal output rate rose with the increasing of light path.The smaller the light path of flat plate bioreactors was,the more content of total lipids,protein and polysaccharide it had in I.galbana cells.[Conclusion] It is an effective way to improve production efficiently and reduce the cost by selecting the suitable bioreactors.展开更多
Photosynthetic microorganisms are important bioresources for producing desirable and environmentally benign products, and photobioreactors (PBRs) play important roles in these processes. Designing PBRs for photocataly...Photosynthetic microorganisms are important bioresources for producing desirable and environmentally benign products, and photobioreactors (PBRs) play important roles in these processes. Designing PBRs for photocatalysis is still challenging at present, and most reactors are designed and scaled up using semi- empirical approaches. No appropriate types of PBRs are available for mass cultivation due to the reactors' high capital and operating costs and short lifespan, which are mainly due to a current lack of deep understanding of the coupling of light, hydrodynamics, mass transfer, and cell growth in efficient reactor design. This review provides a critical overview of the key parameters that influence the performance of the PBRs, including light, mixing, mass transfer, temperature, pH, and capital and operating costs. The lifespan and the costs of cleaning and temperature control are also emphasized for commercial exploitation. Four types of PBRs-tubular, plastic bag, column airlift, and flat-panel airlift reactors are recommended for large- scale operations. In addition, this paper elaborates the modeling of PBRs using the tools of computational fluid dynamics for rational design. It also analyzes the difficulties in the numerical simulation, and presents the prospect for mechanism-based models.展开更多
A coupled system consisting of an upflow membrane-less microbial fuel cell (upflow ML-MFC) and a photobioreactor was developed, and its effectiveness for continuous wastewater treatment and electricity production was ...A coupled system consisting of an upflow membrane-less microbial fuel cell (upflow ML-MFC) and a photobioreactor was developed, and its effectiveness for continuous wastewater treatment and electricity production was evaluated. Wastewater was fed to the upflow ML-MFC to remove chemical oxygen demand (COD), phosphorus and nitrogen with simultaneous electricity generation. The effluent from the cathode compartment of the upflow ML-MFC was then continuously fed to an external photobioreactor for removing the remaining phosphorus and nitrogen using microalgae. Alone, the upflow ML-MFC produces a maximum power density of 481 mW/m 3 , and obtains 77.9% COD, 23.5% total phosphorus (TP) and 97.6% NH4+-N removals. When combined with the photobioreactor, the system achieves 99.3% TP and 99.0% NH4+-N total removal. These results show both the effectiveness and the potential application of the coupled system to continuously treat domestic wastewater and simultaneously generate electricity and biomass.展开更多
This paper presents the design of a novel photobioreactor for cultivation of microalgae. The body of the reactor with volume of about 40 L is parallelipipedic and divided in five compartments that can be put in series...This paper presents the design of a novel photobioreactor for cultivation of microalgae. The body of the reactor with volume of about 40 L is parallelipipedic and divided in five compartments that can be put in series. The optical guides, plunged perpendicularly into the compartments, are upright Plexiglas plates on which side faces there are able to diffuse light laterally and ensure an even distribution of light in the medium. External airlifts through the side columns are used for mixing of culture medium. The external light source is a SON-T lamp mounted inside a projector that provides a conical light dispersion, it is interchangeable and may take different positions. The design offers the photobioreactor characteristics including mainly interchangeable light source, homogenous distribution of light, perfect mixing of suspension of algae, high ratio of illuminating surface to volume of reactor, compactness and absence of contamination. Schemes, view of the photobioractor and data of continuous culture forSpirulina maxima are presented.展开更多
A 4.34 liter two stage air lift photobioreactor incorporating Anabaena variabilis ATCC29413 mutant PK84 was used to study H 2 production. Results showed that H 2 production increased with increasing light intensity fr...A 4.34 liter two stage air lift photobioreactor incorporating Anabaena variabilis ATCC29413 mutant PK84 was used to study H 2 production. Results showed that H 2 production increased with increasing light intensity from 47 μE/(m 2·s) up to 190 μE/(m 2·s), but that further increase of light intensity decreased the H 2 production because of the inhibition due to the high pO 2. The data also indicated that longer argon gas charge resulted in more H 2 produced due to the increase of nitrogenase activities and heterocyst frequency, and that more than 1.3 L net H 2 was produced from this computer controlled photobioreactor.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
H2 photoproduction and nitrogenase activities in two strains of Anabaena variabilismarked wild type ATCC 29413 and mutant PK84 exposed to thermal stress (temperature higher than thenormal incubation temperature of 30...H2 photoproduction and nitrogenase activities in two strains of Anabaena variabilismarked wild type ATCC 29413 and mutant PK84 exposed to thermal stress (temperature higher than thenormal incubation temperature of 30℃) were studied. Cultures of both strains collected from any intervalof logarithmic growth phase exhibited high H2 photoproduction and nitrogenase activities when exposed tolimited time heat shock during the assay process. In contrast, the algal H2 photoproduction rate of bothstrains fluctuated with long term thermal stress caused hy increasing the growth temperature from 30℃ to36℃.The changes of nitrogenase (the key H2 photobiosynhetic enzyme) activities in the mutant PK84showed variation tendency similar to that of H2 photoproduction during exposure to thermal stress, indicat-ing that fluctuation of H2 photopnduction in the mutant was mainly due to the variation of nitrogenase ac-tivities. A temporary maximal H2 photoproduction in the mutant PK84 (wild type ATCC29413 ) was ob-served when cells po at 36℃ for 14 (6) days. However, the responses of nitrogenase activities in thewild type to thermal stress were not completely similar to those in the mutant in spite of similar variationsof H2 photoproduction in both strains. The data obtained in these studies suggested tha the activities ofother enzymes (in the wild strain) involved in H2 photoproduction were affected by thermal stress since H2photoporduction maximized or dropped to 0 without variation tendency similar to that of nitrogenase activi-ties.Furthermore, an enhancement of H2 photoproduction speed of the mutant strain cultured in a 4.4 Llaboratory photobioreactor was also observed when it was subjected to short time continuous charge of ar-gon, and temperature rise.All these results indicated that high temperature plays an important role in the photo-autotrophic H2photoproduction, and that long term thermal stress is unfavourable for net H2 phooproduction in bothstrains of A. variabilis though short-time heat shock is conducive to H2 photoproduction.展开更多
An overview of photobioreactors now in use for production of microalgae world wide is presented, and the application of photobioreactors to the cultivation of microalgae is discussed in detail. It is pointed out that ...An overview of photobioreactors now in use for production of microalgae world wide is presented, and the application of photobioreactors to the cultivation of microalgae is discussed in detail. It is pointed out that high cell density and industrial production of microalgae can be achieved using many kinds of closed photobioreactors including fermentor, tubular and flat plate photobioreactors, and the cultivation of Spirulina, Chlorella, Dunaliella tertiolecta and Porphyridium cruentrim by photobioreactors can achieve higher and steadier productivity than the cultivation of microalgae by an open air system. More and more researches indicate that tubular and flat plate photobioreactors are the development trend for photobioreactors with bubbles and air lift stirrers, and high bright light emitting diodes are the most economic light source with great potential for future development of photobioreactors. Photobioreactors can also be used for the production of high value metabolite (EPA or DHA) using some microalgae species for energy development and environment protection.展开更多
Tetraselmis sp.-1 is a new microalgae strain constructed by cell fusion technique. In this paper, the mixotrophic cultivation of Tetraselmis sp.-1 in airlift photobioreactor is investigated. Firstly, the paper calcula...Tetraselmis sp.-1 is a new microalgae strain constructed by cell fusion technique. In this paper, the mixotrophic cultivation of Tetraselmis sp.-1 in airlift photobioreactor is investigated. Firstly, the paper calculates the light attenuation in the mixotrophic medium, and sets the light attenuation model. Secondly, it uses the same dissolved oxygen coefficient (K d) of flask culture to select the aeration of bioreactor. Finally, it sets the growth kinetic model, production (chlorophyll-a and total lipid) kinetic models and substrate (glucose) consumption kinetic model of Tetraselmis sp.-1 in airlift photobioreactor.展开更多
Microalgae are unicellular organisms capable of photosynthesis, turning sunlight and carbon dioxide (CO2) into rich biomass. Precisely because of this definition, in recent years various sectors have been targeting th...Microalgae are unicellular organisms capable of photosynthesis, turning sunlight and carbon dioxide (CO2) into rich biomass. Precisely because of this definition, in recent years various sectors have been targeting their ability to reduce CO2 emissions and the capacity of simultaneously synthesize biomass which can be later used to produce bio-fuels. Besides being considered fast-growth microorganisms, microalgae have a diverse biochemical composition with similar characteristics to traditional biomass. In this context, the present work aimed to evaluate the biofixation of CO2 by the microalgae Monoraphidium sp., cultivated in a closed-window type photobioreactor, as well as characterization of microalgal biomass produced in relation to the total lipid content (TL), lipids converted into biodiesel (LCB), carbohydrates and proteins. The results achieved showed that the best result was obtained after 24 h of cultivation, where for each gram of biomass produced approximately 1.2 g of CO2 were consumed. In the growth phase the average biomass productivity in the Janela photobioreactor was 58 mg·L-1·day-1 concluding that microalgae culture systems could be coupled to the chimneys of large industries emitters CO2 using this gas, resulting from combustion processes, in the process of photosynthesis. The biomass Monoraphidium sp. produced had a content of lipids converted into biodiesel of approximately 8.36% ± 2.69%, carbohydrates 32% ± 3.37% and proteins 34.26% ± 0.41%.展开更多
This paper presents the investigation on biosynthesis of high-value-added amino acids and sugars labeled uniformly with stable isotope 13C by microalga Spirulina (Arthrospira) maxima in a parallelepiped photobioreacto...This paper presents the investigation on biosynthesis of high-value-added amino acids and sugars labeled uniformly with stable isotope 13C by microalga Spirulina (Arthrospira) maxima in a parallelepiped photobioreactor. The kinetic data of both batch and continuous cultures with characterization of the amino acids and sugars are shown. The continuous culture without nutrients deficiency is for biosynthesis of amino acids, with tyrosine as one of the principal constituents, and the batch culture with deficiency in nitrogen is for biosynthesis of labeled glucose that is up to 64% versus dry mass of cells.展开更多
The key limiting factors to high-density culture of Porphyridium cruentum are the uptake of light energy and nutrient by the microalgal cells. Under the optimal conditions of carrier culture, both cell mass and cell d...The key limiting factors to high-density culture of Porphyridium cruentum are the uptake of light energy and nutrient by the microalgal cells. Under the optimal conditions of carrier culture, both cell mass and cell density were increased significantly up to 5.2 g/L (DW) and 5.2107/ml. Furthermore, the effects of the liquid circulation velocity, light intensity and initial cell density on cell mass productivity of P. cruentum were investigated in a 42 L internal loop airlift photobioreactor. Although the light intensity was as low as 100 mmol/(m2s), the light damage or the photoinhibition phenomenon was observed under the culture condition of low initial cell mass (0.10 g/L, DW) and high liquid circulation velocity (0.30 m/s). However, a higher cell growth rate and a high cell mass productivity were achieved with the same conditions only at high initial cell mass (about 0.80 g/L, DW). Under the optimal conditions, the cell specific growth rate, cell mass volumetric and areal output rate reached to 0.95 d-1, 0.80 g/(Ld) and 42.5 g/(m2d) respectively. Finally, a method of nutrient feeding and gradual increase of light intensity in different cultural stages was developed, which further improved the cell mass, cell mass volumetric and areal output rate to 5.9 g/L, 1.2 g/(Ld) and 61.7 g/(m2d) respectively.展开更多
A comprehensive numerical model is developed to simulate the growth of microalgae under light/dark cycling conditions.The purpose of this study is to predict the growth rate of Chlorella vulgaris cultivated in photobi...A comprehensive numerical model is developed to simulate the growth of microalgae under light/dark cycling conditions.The purpose of this study is to predict the growth rate of Chlorella vulgaris cultivated in photobioreactors(PBRs)in order to improve the light conditions for microalgae and enhance the photosynthetic efficiency.Computational fluid dynamics(CFD)is used to simulate its internal hydrodynamic behaviors.The Lagrangian method is employed to track the movement of microalgae cells.The radiative transfer equation(RTE)is used to obtain light intensity distribution.The combination of light radiation field and microalgae cell motions is used to construct the light history and they are integrated into the model of the photosynthetic units(PSU)to calculate the microalgae growth rate.The numerical results demonstrate that enhanced light/dark cycling frequency with ordered mixing can promote efficient microalgae cultivation.The effect of the vortex flow field generated by the baffles in an air-lift PBR is analyzed for increasing microalgae growth rate.When using the 1:1 baffle spacing,the biomass production of microalgae is increased by 41.8% compared to the original PBR.展开更多
Microalgae cultivation in photobioreactors(PBRs)has emerged as a promising and sustainable approach to address various environmental and energy challenges,offering a multitude of benefits across diverse applications.R...Microalgae cultivation in photobioreactors(PBRs)has emerged as a promising and sustainable approach to address various environmental and energy challenges,offering a multitude of benefits across diverse applications.Recent developments in microalgae cultivation in photobioreactors have contributed substantially to the development and optimization of sustainable bioprocesses.This review presents a comprehensive analysis of recent innovations and breakthroughs in the field of microalgae cultivation,with a specific focus on their application in photobioreactors,aimed at paving the way for a greener future.This study in-depth examines the advantages of microalgae cultivation in photobioreactors,concentrating on its effectiveness in wastewater treatment,CO_(2)bioremediation,and the production of biofuels and high-value products.The review evaluates the effects of light,solar irradiation,temperature,nitrogen and phosphorus concentrations in culture media,CO_(2)concentrations,and pH on microalgae growth performance,including specific growth and biomass productivity.The study also examines open systems like unstirred ponds,raceway ponds,and circular ponds and closed systems like horizontal tubular,vertical bubble-column,airlift,flat panel,and plastic-bag photobioreactors,comparing their pros and cons.To optimize microalgae cultivation,key factors in photobioreactor design,including photosynthetic efficiencies,light/dark(L/D)cycles,CO_(2)concentrations,mass transfer,hydrodynamics behavior,and p H,are extensively investigated.In addition,the review outlines recent developments in large-scale photobioreactors and highlights the challenges and opportunities associated with photobioreactor scale-up and design parameter optimization,including genetic engineering and economic feasibility.This article is a vital resource for researchers,engineers,and industry professionals seeking sustainable bioprocesses and the application of microalgae-based technologies.展开更多
One of the most important solutions to overcome energy and environmental problems and to replace the fossil fuel-based economy could be the use of photosynthetic microorganisms.The use of photosynthetic microorganisms...One of the most important solutions to overcome energy and environmental problems and to replace the fossil fuel-based economy could be the use of photosynthetic microorganisms.The use of photosynthetic microorganisms is a potential alternative to energy generation from fossil fuels because they efficiently produce hydrogen(H_(2)).Immobilization of photosynthetic microorganisms is used for many biotechnological applications such as H_(2) production.This method appears attractive because it restricts cell movement in an entrapped matrix.Immobilization of Rhodopseudomonas sp.S16-VOGS3 cells is a promising way to improve H_(2) production.In this work,the ability of immobilized Rhodopseudomonas sp.S16-VOGS3 cells to produce H_(2) was investigated in two types of PBRs.The PBRs used in this work were a cylindrical one with 0.2 L working volume(C-PBR)and a flat Roux type with 0.6 L working volume(FRT-PBR).The calcium alginate beads prepared were resistant to culture mixing and showed little leakage of cells,and the immobilized cells continued the photofermentation process in both PBRs.The immobilized cells in the C-PBR produced 936.8 mL of H_(2) with an average H_(2) production rate of 2.99 mL/h.The average productivity was 126.4μL(H_(2))/mg(cells)/h or 14.96 mL(H_(2))/L(culture)/h,and the light conversion efficiency was 2.37%.The immobilized cells in the FRT-PBR produced a total of 662.2 mL of H_(2) with an average H_(2) production rate of 1.55 mL/h.The average productivity was 31.1μL(H_(2))/mg(cells)/h or 2.58 mL(H_(2))/L(culture)/h,and the light conversion efficiency was 0.52%.The more uniform and therefore more efficient degree of bacterial cell mixing achieved in the C-PBR with cylindrical configuration played an important role compared to the FRT-PBR.In the FRT-PBR,the beads were aggregated at the bottom,which limited light penetration and resulted in low H_(2) production efficiency.展开更多
Microalgae possess significant advantages in nitrogen and phosphorus removal from nutrient-richwastewater that are highly efficient and independent of the C/N ratio.However,challenges such as low biomass productivity,...Microalgae possess significant advantages in nitrogen and phosphorus removal from nutrient-richwastewater that are highly efficient and independent of the C/N ratio.However,challenges such as low biomass productivity,high variability in nutrient removal under different trophic types,and difficulty in harvesting biomass limits the large-scale application of microalgae wastewater treatment.This study attempted to employmixotrophic microalgae biofilm to address these issues.The biomass production,microalgal activity,and nutrient removal of Chlorella pyrenoidosa biofilms with different trophic types were compared for nutrient-rich wastewater treatment.The results showed that the biomass productivity of the mixotrophic microalgal biofilm(0.215 g/(L·d))was 2.3,8.6,and 6.0 times higher than that of photoautotrophic microalgal biofilm,heterotrophic microalgal biofilm,and photoautotrophic suspended microalga,respectively.Additionally,the dehydrogenase activity(DHA),indicating microalgal activity,of the mixotrophic biofilm was 2.3 and 16.5 times higher than that of photoautotrophic and heterotrophic biofilms,respectively.Meanwhile,the mixotrophic biofilm removed 96.0%of NH_(4)^(+)-N and 99.2%of PO_(4)^(3-)-P,more efficient than that with other types of biofilms and suspended microalgae.In an open-ended air-lift photobioreactor,the mixotrophic microalgal biofilm produced biomass at 0.12 g/(L·d)and removed 90.0%of NH_(4)^(+)-N and 97.6%of PO_(4)^(3-)-P.This study suggests that the mixotrophic microalgal biofilm shows promise in treating nutrient-rich wastewater and producing microalgal biomass for value-added products.展开更多
基金Membranes and Water Security IRC,KFUPM.Funding no.INMW2304。
文摘Produced water(PW)from oil and gas exploration adversely affects aquatic life and living organisms,necessitating treatment before discharge to meet effluent permissible limits.This study first used activated sludge to pretreat PW in a sequential batch reactor(SBR).The pretreated PW then entered a 13 L photobioreactor(PBR)containing Scenedesmus obliquus microalgae culture.Initially,10%of the PW mixed with 90%microalgae culture in the PBR.After the exponential growth of the microalgae,an additional 25%of PW was added to the PBR without extra nutrients.This study reported the growth performance of microalgae in the PBR as well as the reduction in effluent’s total organic carbon(TOC),total dissolved solids(TDS),electrical conductivity(EC),and heavy metals content.The results demonstrated removal efficiencies of 64%for TOC,49.8%for TDS,and 49.1%for EC.The results also showed reductions in barium,iron,and manganese in the effluent by 95,76,and 52%,respectively.
基金Supported by National Ministry of Science and Technology Marine‘863’Marine Life Technology Plan Project(2008AA09Z403)Shangdong High School Technological Plan Project(J05I03)~~
文摘[Objective] The paper aims to provide references to cultivate I.galbana in a large scale and explore its medical value.[Method] I.galbana had been cultivated in different light-path flat plate bioreactors,and the growth condition and content of organic matter within cells of I.galbana had been analyzed.[Result] Growth rate and volumetric productivity of I.galbana cells increased as light-path of flat plate bioreactors decreased,however,daily areal output rate rose with the increasing of light path.The smaller the light path of flat plate bioreactors was,the more content of total lipids,protein and polysaccharide it had in I.galbana cells.[Conclusion] It is an effective way to improve production efficiently and reduce the cost by selecting the suitable bioreactors.
基金This work was supported by the National Key Research and De- velopment Program of China (2016YFB0301701) the National Nat- ural Science Foundation of China (91434114, 21376254)+2 种基金 the Major National Scientific Instrument Development Project (21427814) the Instrument Developing Project of the Chinese Academy of Sciences (YZ201641) the International Partnership Program for Creative Re-search Teams, Chinese Academy of Sciences, and the Supercomput- ing Center of USTC (University of Science and Technology of China).
文摘Photosynthetic microorganisms are important bioresources for producing desirable and environmentally benign products, and photobioreactors (PBRs) play important roles in these processes. Designing PBRs for photocatalysis is still challenging at present, and most reactors are designed and scaled up using semi- empirical approaches. No appropriate types of PBRs are available for mass cultivation due to the reactors' high capital and operating costs and short lifespan, which are mainly due to a current lack of deep understanding of the coupling of light, hydrodynamics, mass transfer, and cell growth in efficient reactor design. This review provides a critical overview of the key parameters that influence the performance of the PBRs, including light, mixing, mass transfer, temperature, pH, and capital and operating costs. The lifespan and the costs of cleaning and temperature control are also emphasized for commercial exploitation. Four types of PBRs-tubular, plastic bag, column airlift, and flat-panel airlift reactors are recommended for large- scale operations. In addition, this paper elaborates the modeling of PBRs using the tools of computational fluid dynamics for rational design. It also analyzes the difficulties in the numerical simulation, and presents the prospect for mechanism-based models.
基金Projects(2009GG10005004, 2010GHY10504) supported by the Scientific and Technological Foundation of Shandong Province,ChinaProject(2011GHY11531) supported by the Science and Technology Development Program of Shandong Province,ChinaProject(ZR2009BM015) supported by the Natural Science Foundation of Shandong Province,China
文摘A coupled system consisting of an upflow membrane-less microbial fuel cell (upflow ML-MFC) and a photobioreactor was developed, and its effectiveness for continuous wastewater treatment and electricity production was evaluated. Wastewater was fed to the upflow ML-MFC to remove chemical oxygen demand (COD), phosphorus and nitrogen with simultaneous electricity generation. The effluent from the cathode compartment of the upflow ML-MFC was then continuously fed to an external photobioreactor for removing the remaining phosphorus and nitrogen using microalgae. Alone, the upflow ML-MFC produces a maximum power density of 481 mW/m 3 , and obtains 77.9% COD, 23.5% total phosphorus (TP) and 97.6% NH4+-N removals. When combined with the photobioreactor, the system achieves 99.3% TP and 99.0% NH4+-N total removal. These results show both the effectiveness and the potential application of the coupled system to continuously treat domestic wastewater and simultaneously generate electricity and biomass.
文摘This paper presents the design of a novel photobioreactor for cultivation of microalgae. The body of the reactor with volume of about 40 L is parallelipipedic and divided in five compartments that can be put in series. The optical guides, plunged perpendicularly into the compartments, are upright Plexiglas plates on which side faces there are able to diffuse light laterally and ensure an even distribution of light in the medium. External airlifts through the side columns are used for mixing of culture medium. The external light source is a SON-T lamp mounted inside a projector that provides a conical light dispersion, it is interchangeable and may take different positions. The design offers the photobioreactor characteristics including mainly interchangeable light source, homogenous distribution of light, perfect mixing of suspension of algae, high ratio of illuminating surface to volume of reactor, compactness and absence of contamination. Schemes, view of the photobioractor and data of continuous culture forSpirulina maxima are presented.
文摘A 4.34 liter two stage air lift photobioreactor incorporating Anabaena variabilis ATCC29413 mutant PK84 was used to study H 2 production. Results showed that H 2 production increased with increasing light intensity from 47 μE/(m 2·s) up to 190 μE/(m 2·s), but that further increase of light intensity decreased the H 2 production because of the inhibition due to the high pO 2. The data also indicated that longer argon gas charge resulted in more H 2 produced due to the increase of nitrogenase activities and heterocyst frequency, and that more than 1.3 L net H 2 was produced from this computer controlled photobioreactor.
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H2 photoproduction and nitrogenase activities in two strains of Anabaena variabilismarked wild type ATCC 29413 and mutant PK84 exposed to thermal stress (temperature higher than thenormal incubation temperature of 30℃) were studied. Cultures of both strains collected from any intervalof logarithmic growth phase exhibited high H2 photoproduction and nitrogenase activities when exposed tolimited time heat shock during the assay process. In contrast, the algal H2 photoproduction rate of bothstrains fluctuated with long term thermal stress caused hy increasing the growth temperature from 30℃ to36℃.The changes of nitrogenase (the key H2 photobiosynhetic enzyme) activities in the mutant PK84showed variation tendency similar to that of H2 photoproduction during exposure to thermal stress, indicat-ing that fluctuation of H2 photopnduction in the mutant was mainly due to the variation of nitrogenase ac-tivities. A temporary maximal H2 photoproduction in the mutant PK84 (wild type ATCC29413 ) was ob-served when cells po at 36℃ for 14 (6) days. However, the responses of nitrogenase activities in thewild type to thermal stress were not completely similar to those in the mutant in spite of similar variationsof H2 photoproduction in both strains. The data obtained in these studies suggested tha the activities ofother enzymes (in the wild strain) involved in H2 photoproduction were affected by thermal stress since H2photoporduction maximized or dropped to 0 without variation tendency similar to that of nitrogenase activi-ties.Furthermore, an enhancement of H2 photoproduction speed of the mutant strain cultured in a 4.4 Llaboratory photobioreactor was also observed when it was subjected to short time continuous charge of ar-gon, and temperature rise.All these results indicated that high temperature plays an important role in the photo-autotrophic H2photoproduction, and that long term thermal stress is unfavourable for net H2 phooproduction in bothstrains of A. variabilis though short-time heat shock is conducive to H2 photoproduction.
文摘An overview of photobioreactors now in use for production of microalgae world wide is presented, and the application of photobioreactors to the cultivation of microalgae is discussed in detail. It is pointed out that high cell density and industrial production of microalgae can be achieved using many kinds of closed photobioreactors including fermentor, tubular and flat plate photobioreactors, and the cultivation of Spirulina, Chlorella, Dunaliella tertiolecta and Porphyridium cruentrim by photobioreactors can achieve higher and steadier productivity than the cultivation of microalgae by an open air system. More and more researches indicate that tubular and flat plate photobioreactors are the development trend for photobioreactors with bubbles and air lift stirrers, and high bright light emitting diodes are the most economic light source with great potential for future development of photobioreactors. Photobioreactors can also be used for the production of high value metabolite (EPA or DHA) using some microalgae species for energy development and environment protection.
文摘Tetraselmis sp.-1 is a new microalgae strain constructed by cell fusion technique. In this paper, the mixotrophic cultivation of Tetraselmis sp.-1 in airlift photobioreactor is investigated. Firstly, the paper calculates the light attenuation in the mixotrophic medium, and sets the light attenuation model. Secondly, it uses the same dissolved oxygen coefficient (K d) of flask culture to select the aeration of bioreactor. Finally, it sets the growth kinetic model, production (chlorophyll-a and total lipid) kinetic models and substrate (glucose) consumption kinetic model of Tetraselmis sp.-1 in airlift photobioreactor.
基金We thank the National Council for Scientific and Technological Development(CNPq)for the financial support and the GREENTEC Laboratory(UFRJ)for their support in the research.
文摘Microalgae are unicellular organisms capable of photosynthesis, turning sunlight and carbon dioxide (CO2) into rich biomass. Precisely because of this definition, in recent years various sectors have been targeting their ability to reduce CO2 emissions and the capacity of simultaneously synthesize biomass which can be later used to produce bio-fuels. Besides being considered fast-growth microorganisms, microalgae have a diverse biochemical composition with similar characteristics to traditional biomass. In this context, the present work aimed to evaluate the biofixation of CO2 by the microalgae Monoraphidium sp., cultivated in a closed-window type photobioreactor, as well as characterization of microalgal biomass produced in relation to the total lipid content (TL), lipids converted into biodiesel (LCB), carbohydrates and proteins. The results achieved showed that the best result was obtained after 24 h of cultivation, where for each gram of biomass produced approximately 1.2 g of CO2 were consumed. In the growth phase the average biomass productivity in the Janela photobioreactor was 58 mg·L-1·day-1 concluding that microalgae culture systems could be coupled to the chimneys of large industries emitters CO2 using this gas, resulting from combustion processes, in the process of photosynthesis. The biomass Monoraphidium sp. produced had a content of lipids converted into biodiesel of approximately 8.36% ± 2.69%, carbohydrates 32% ± 3.37% and proteins 34.26% ± 0.41%.
基金Supported by the Scholarship of Faculte Polytechnique de Mons, Belgium and by the Fund for Scholars Returning from Abroad.
文摘This paper presents the investigation on biosynthesis of high-value-added amino acids and sugars labeled uniformly with stable isotope 13C by microalga Spirulina (Arthrospira) maxima in a parallelepiped photobioreactor. The kinetic data of both batch and continuous cultures with characterization of the amino acids and sugars are shown. The continuous culture without nutrients deficiency is for biosynthesis of amino acids, with tyrosine as one of the principal constituents, and the batch culture with deficiency in nitrogen is for biosynthesis of labeled glucose that is up to 64% versus dry mass of cells.
基金Supported by the China Ministry of Science and Technology(No. 96-C02-04-05)
文摘The key limiting factors to high-density culture of Porphyridium cruentum are the uptake of light energy and nutrient by the microalgal cells. Under the optimal conditions of carrier culture, both cell mass and cell density were increased significantly up to 5.2 g/L (DW) and 5.2107/ml. Furthermore, the effects of the liquid circulation velocity, light intensity and initial cell density on cell mass productivity of P. cruentum were investigated in a 42 L internal loop airlift photobioreactor. Although the light intensity was as low as 100 mmol/(m2s), the light damage or the photoinhibition phenomenon was observed under the culture condition of low initial cell mass (0.10 g/L, DW) and high liquid circulation velocity (0.30 m/s). However, a higher cell growth rate and a high cell mass productivity were achieved with the same conditions only at high initial cell mass (about 0.80 g/L, DW). Under the optimal conditions, the cell specific growth rate, cell mass volumetric and areal output rate reached to 0.95 d-1, 0.80 g/(Ld) and 42.5 g/(m2d) respectively. Finally, a method of nutrient feeding and gradual increase of light intensity in different cultural stages was developed, which further improved the cell mass, cell mass volumetric and areal output rate to 5.9 g/L, 1.2 g/(Ld) and 61.7 g/(m2d) respectively.
基金supported by Major Program of the National Natural Science Foundation of China(No.52293413)the National Natural Science Foundation of China(No.52076161)。
文摘A comprehensive numerical model is developed to simulate the growth of microalgae under light/dark cycling conditions.The purpose of this study is to predict the growth rate of Chlorella vulgaris cultivated in photobioreactors(PBRs)in order to improve the light conditions for microalgae and enhance the photosynthetic efficiency.Computational fluid dynamics(CFD)is used to simulate its internal hydrodynamic behaviors.The Lagrangian method is employed to track the movement of microalgae cells.The radiative transfer equation(RTE)is used to obtain light intensity distribution.The combination of light radiation field and microalgae cell motions is used to construct the light history and they are integrated into the model of the photosynthetic units(PSU)to calculate the microalgae growth rate.The numerical results demonstrate that enhanced light/dark cycling frequency with ordered mixing can promote efficient microalgae cultivation.The effect of the vortex flow field generated by the baffles in an air-lift PBR is analyzed for increasing microalgae growth rate.When using the 1:1 baffle spacing,the biomass production of microalgae is increased by 41.8% compared to the original PBR.
基金support received from Interdisciplinary Research Center for Refining and Advanced Chemicals,King Fahd University of Petroleum&Minerals,Dhahran,Saudi Arabia with funding grant and financial support for this work through project No.INRC2318
文摘Microalgae cultivation in photobioreactors(PBRs)has emerged as a promising and sustainable approach to address various environmental and energy challenges,offering a multitude of benefits across diverse applications.Recent developments in microalgae cultivation in photobioreactors have contributed substantially to the development and optimization of sustainable bioprocesses.This review presents a comprehensive analysis of recent innovations and breakthroughs in the field of microalgae cultivation,with a specific focus on their application in photobioreactors,aimed at paving the way for a greener future.This study in-depth examines the advantages of microalgae cultivation in photobioreactors,concentrating on its effectiveness in wastewater treatment,CO_(2)bioremediation,and the production of biofuels and high-value products.The review evaluates the effects of light,solar irradiation,temperature,nitrogen and phosphorus concentrations in culture media,CO_(2)concentrations,and pH on microalgae growth performance,including specific growth and biomass productivity.The study also examines open systems like unstirred ponds,raceway ponds,and circular ponds and closed systems like horizontal tubular,vertical bubble-column,airlift,flat panel,and plastic-bag photobioreactors,comparing their pros and cons.To optimize microalgae cultivation,key factors in photobioreactor design,including photosynthetic efficiencies,light/dark(L/D)cycles,CO_(2)concentrations,mass transfer,hydrodynamics behavior,and p H,are extensively investigated.In addition,the review outlines recent developments in large-scale photobioreactors and highlights the challenges and opportunities associated with photobioreactor scale-up and design parameter optimization,including genetic engineering and economic feasibility.This article is a vital resource for researchers,engineers,and industry professionals seeking sustainable bioprocesses and the application of microalgae-based technologies.
基金supported by European Union's Horizon Europe-the Framework Programme for Research and Innovation[grant number 101093150]project LIBRA(Light Based Multisensing Device for Screening of Pathogens and Nutrients in Bioreactors)。
文摘One of the most important solutions to overcome energy and environmental problems and to replace the fossil fuel-based economy could be the use of photosynthetic microorganisms.The use of photosynthetic microorganisms is a potential alternative to energy generation from fossil fuels because they efficiently produce hydrogen(H_(2)).Immobilization of photosynthetic microorganisms is used for many biotechnological applications such as H_(2) production.This method appears attractive because it restricts cell movement in an entrapped matrix.Immobilization of Rhodopseudomonas sp.S16-VOGS3 cells is a promising way to improve H_(2) production.In this work,the ability of immobilized Rhodopseudomonas sp.S16-VOGS3 cells to produce H_(2) was investigated in two types of PBRs.The PBRs used in this work were a cylindrical one with 0.2 L working volume(C-PBR)and a flat Roux type with 0.6 L working volume(FRT-PBR).The calcium alginate beads prepared were resistant to culture mixing and showed little leakage of cells,and the immobilized cells continued the photofermentation process in both PBRs.The immobilized cells in the C-PBR produced 936.8 mL of H_(2) with an average H_(2) production rate of 2.99 mL/h.The average productivity was 126.4μL(H_(2))/mg(cells)/h or 14.96 mL(H_(2))/L(culture)/h,and the light conversion efficiency was 2.37%.The immobilized cells in the FRT-PBR produced a total of 662.2 mL of H_(2) with an average H_(2) production rate of 1.55 mL/h.The average productivity was 31.1μL(H_(2))/mg(cells)/h or 2.58 mL(H_(2))/L(culture)/h,and the light conversion efficiency was 0.52%.The more uniform and therefore more efficient degree of bacterial cell mixing achieved in the C-PBR with cylindrical configuration played an important role compared to the FRT-PBR.In the FRT-PBR,the beads were aggregated at the bottom,which limited light penetration and resulted in low H_(2) production efficiency.
基金supported by the Natural Science Foundation of Guangdong Province(No.2020A1515011113)the Applied Basic Research Project of Guangzhou(No.202002030455)Zhongshan Science and Technology Plan Project(No.2020AG021).
文摘Microalgae possess significant advantages in nitrogen and phosphorus removal from nutrient-richwastewater that are highly efficient and independent of the C/N ratio.However,challenges such as low biomass productivity,high variability in nutrient removal under different trophic types,and difficulty in harvesting biomass limits the large-scale application of microalgae wastewater treatment.This study attempted to employmixotrophic microalgae biofilm to address these issues.The biomass production,microalgal activity,and nutrient removal of Chlorella pyrenoidosa biofilms with different trophic types were compared for nutrient-rich wastewater treatment.The results showed that the biomass productivity of the mixotrophic microalgal biofilm(0.215 g/(L·d))was 2.3,8.6,and 6.0 times higher than that of photoautotrophic microalgal biofilm,heterotrophic microalgal biofilm,and photoautotrophic suspended microalga,respectively.Additionally,the dehydrogenase activity(DHA),indicating microalgal activity,of the mixotrophic biofilm was 2.3 and 16.5 times higher than that of photoautotrophic and heterotrophic biofilms,respectively.Meanwhile,the mixotrophic biofilm removed 96.0%of NH_(4)^(+)-N and 99.2%of PO_(4)^(3-)-P,more efficient than that with other types of biofilms and suspended microalgae.In an open-ended air-lift photobioreactor,the mixotrophic microalgal biofilm produced biomass at 0.12 g/(L·d)and removed 90.0%of NH_(4)^(+)-N and 97.6%of PO_(4)^(3-)-P.This study suggests that the mixotrophic microalgal biofilm shows promise in treating nutrient-rich wastewater and producing microalgal biomass for value-added products.
