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A new approach to heart valve tissue engineering: mimicking the heart ventricle with a ventricular assist device in a novel bioreactor

KAASI, Andreas; CESTARI, Idagene A.; STOLF, Noedir A. G.; LEIRNER, Adolfo A.; HASSAGER, Ole; CESTARI, Ismar N.
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.1%
The `biomimetic` approach to tissue engineering usually involves the use of a bioreactor mimicking physiological parameters whilst supplying nutrients to the developing tissue. Here we present a new heart valve bioreactor, having as its centrepiece a ventricular assist device (VAD), which exposes the cell-scaffold constructs to a wider array of mechanical forces. The pump of the VAD has two chambers: a blood and a pneumatic chamber, separated by an elastic membrane. Pulsatile air-pressure is generated by a piston-type actuator and delivered to the pneumatic chamber, ejecting the fluid in the blood chamber. Subsequently, applied vacuum to the pneumatic chamber causes the blood chamber to fill. A mechanical heart valve was placed in the VAD`s inflow position. The tissue engineered (TE) valve was placed in the outflow position. The VAD was coupled in series with a Windkessel compliance chamber, variable throttle and reservoir, connected by silicone tubings. The reservoir sat on an elevated platform, allowing adjustment of ventricular preload between 0 and 11 mmHg. To allow for sterile gaseous exchange between the circuit interior and exterior, a 0.2 mu m filter was placed at the reservoir. Pressure and flow were registered downstream of the TE valve. The circuit was filled with culture medium and fitted in a standard 5% CO(2) incubator set at 37 degrees C. Pressure and flow waveforms were similar to those obtained under physiological conditions for the pulmonary circulation. The `cardiomimetic` approach presented here represents a new perspective to conventional biomimetic approaches in TE...

Efeito da adição de lodo ao inóculo de reator anaeróbio híbrido sólido-líquido tratando fração orgânica de resíduos sólidos urbanos; Effects of sludge addition to seed in hybrid anaerobic solid-liquid bioreactor treating organic fraction of municipal solid wastes

Carneiro, Pedro Henrique
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 09/06/2005 PT
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O tratamento de resíduos sólidos orgânicos, como lodos de estação de tratamento de esgotos e a fração orgânica de resíduos sólidos urbanos, são desafios atuais da engenharia sanitária e ambiental. Os processos biológicos são os mais apropriados para o tratamento desses resíduos. Acordos recentes como o Protocolo de Kyoto e os mecanismos de desenvolvimento limpo (MDL) estão contribuindo para o crescimento da digestão anaeróbia de resíduos sólidos orgânicos em todo o mundo. Nesta pesquisa foi investigado o efeito da adição de lodo anaeróbio ao lixiviado de aterro sanitário empregado como inóculo de reator anaeróbio híbrido sólido-líquido tratando a fração orgânica de resíduos sólidos urbanos. Foi verificado que a adição de lodo melhorou a digestão anaeróbia, acelerando a degradação de ácidos graxos voláteis, antecipando a geração de biogás, aumentando a composição percentual de metano e promovendo maior variabilidade e presença de microrganismos. A adição de lodo também aumentou a eficiência de conversão de sólidos totais e sólidos totais voláteis e sólidos totais fixos; Treatment of organic solid wastes like wastewater treatment plant sludges and organic fraction of municipal solid wastes are current issues in environmental engineering. Biological processes are more appropriate to treat these wastes. Recent trends like Kyoto protocol and clean development mechanisms (CDM) are improving anaerobic digestion of organic solid wastes. It was investigated the effect of adding anaerobic sludge to bioreactor landfill leachate applied like seed in hybrid anaerobic solid-liquid bioreactor treating organic fraction of municipal solid wastes. It was verified that sludge addition improved anaerobic digestion...

Desenvolvimento de processo de fermentação em biorreator para produção de prolactina humana secretada no espaço periplásmico de Escherichia coli; Development of the fermentation process in bioreactor for the production of human prolactin secreted in the periplasmic space of Escherichia coli

Oliveira, Taís Lima de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 12/12/2008 PT
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A Prolactina (PRL) é um dos hormônios mais versáteis em termos de ação biológica. Sua ação mais conhecida está relacionada com o estímulo da lactação e regulação do crescimento e da diferenciação da glândula mamária; também apresenta importante aplicação diagnóstica. Somando os crescentes estudos sobre suas possíveis aplicações terapêuticas, fica cada vez mais notória a necessidade da obtenção desse hormônio puro, biologicamente ativo e na sua forma autêntica.O objetivo fundamental desse projeto foi a produção de hPRL em escala laboratorial a partir de bactérias (E.coli) modificadas geneticamente, utilizando um sistema de expressão baseado no promotor Lambda () PL, o mesmo utilizado com sucesso em nosso laboratório na expressão do hGH. Descrevemos nesse trabalho um processo de cultivo em biorreator, onde não foi utilizado o repressor cIts, uma proteína termo-sensível que usualmente é utilizada para inibir o funcionamento do promotor PL durante crescimento a 30ºC. O processo de cultivo apresenta basicamente três etapas: na primeira etapa o crescimento é realizado sem adição contínua de nutrientes (cultivo em batch), na segunda etapa ocorre adição contínua de nutrientes e carboidrato (cultivo em fed-batch) e na última etapa é realizada a ativação...

Cephalosporin C production by immobilized Cephalosporium acremonium cells in a repeated batch tower bioreactor

Cruz, AJG; Pan, T.; Giordano, R. C.; Araujo, MLGC; Hokka, C. O.
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica Formato: 96-102
ENG
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The industrial production of antibiotics with filamentous fungi is usually carried out in conventional aerated and agitated tank fermentors. Highly viscous non-Newtonian broths are produced and a compromise must be found between convenient shear stress and adequate oxygen transfer. In this work, cephalosporin C production by bioparticles of immobilized cells of Cephalosporium acremonium ATCC 48272 was studied in a repeated batch tower bioreactor as an alternative to the conventional process. Also, gas-liquid oxygen transfer volumetric coefficients, k(L)a, were determined at various air flow-rates and alumina contents in the bioparticle. The bioparticles were composed of calcium alginate (2.0% w/w), alumina (<44 micra), cells, and water. A model describing the cell growth, cephalosporin C production, oxygen, glucose, and sucrose consumption was proposed. To describe the radial variation of oxygen concentration within the pellet, the reaction-diffusion model forecasting a dead core bioparticle was adopted. The k(L)a measurements with gel beads prepared with 0.0, 1.0, 1.5, and 2.0% alumina showed that a higher k(L)a value is attained with 1.5 and 2.0%. An expression relating this coefficient to particle density, liquid density, and air velocity was obtained and further utilized in the simulation of the proposed model. Batch...

Hydrodynamic considerations on optimal design of a three-phase airlift bioreactor with high solids loading

Klein, Jaroslav; Vicente, A. A.; Teixeira, J. A.
Fonte: Society of Chemical Industry Publicador: Society of Chemical Industry
Tipo: Artigo de Revista Científica
Publicado em //2003 ENG
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The hydrodynamic study of a three-phase airlift (TPAL) bioreactor with an enlarged gas–liquid dual separator was carried out. Different lengths and diameters of the draft tube were tested to show how the design of the separator zone affects the hydrodynamic performance of the TPAL reactor. Ca-alginate beads with entrapped yeast biomass at different loadings (0, 7, 14 and 21% v/v) were used in order to mimic the solid phase of conventional high cell density systems, such as those with cells immobilized on carriers or flocculating cells. Important information on multiphase flow and distribution of gas and solid phases in the internal-loop airlift reactor (ALR) with high solids loading was obtained, which can be used for suggesting optimal hydrodynamic conditions in a TPAL bioreactor with high solids loading. It is finally suggested that the ALR with a dual separator and a downcomer to riser cross-sectional area ratio (AD/AR) ranging from 1.2 to 2.0 can be successfully applied to batch/continuous high cell density systems, where the uniform distribution of solid phase, its efficient separation of particles from the liquid phase, and an improved residence time of air bubbles inside the reactor are desirable.; European Community - ‘Improving Human Research Potential’ - Marie Curie Fellowship - contract number HPMF-CT-2002-01643.

Contamination of a high-cell-density continuous bioreactor

Domingues, Lucília; Lima, Nelson; Teixeira, J. A.
Fonte: John Wiley & Sons, Inc Publicador: John Wiley & Sons, Inc
Tipo: Artigo de Revista Científica
Publicado em /06/2000 ENG
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Continuous fermentations were carried out with a recombinant flocculent Saccharomyces cerevisiae strain in an airlift bioreactor. Once operating under steady state at a dilution rate of 0.45 h−1, the bioreactor was contaminated with Escherichia coli cells. The faster growing E. coli strain was washed out of the bioreactor and the recombinant, slower growing flocculating S. cerevisiae strain remained as the only species detected in the bioreactor. Flocculation, besides allowing for the realization of high-cell-density systems with corresponding unusual high productivity, may be used as a selective property for controlling some contamination problems associated with prolonged continuous operation.; Fundação para a Ciência e Tecnologia -PRAXIS XXI/BD/11306/97.

Relationships between hydrodynamics and rheology of flocculating yeast suspensions in a high-cell-density airlift bioreactor

Klein, Jaroslav; Maia, J. M.; Vicente, A. A.; Domingues, Lucília; Teixeira, J. A.; Juraščík, Martin
Fonte: John Wiley & Sons, Ltd. Publicador: John Wiley & Sons, Ltd.
Tipo: Artigo de Revista Científica
Publicado em //2005 ENG
Relevância na Pesquisa
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In this article a hydrodynamic and rheological analysis of a continuous airlift bioreactor with high-celldensity system is presented. A highly flocculating recombinant strain of Sacharomyces cerevisiae containing genes for lactose transport (lactose permease) and hydrolysis (β-galactosidase) was exploited to ferment lactose from cheese whey to ethanol. The magnetic particle-tracer method was used to assess the effect of operational conditions (air-flow rate, biomass concentration) on hydrodynamic behavior of an airlift bioreactor during the fermentation process. Measurements of liquid circulation velocity showed the existence of a critical value of biomass concentration at which a dramatic deceleration of net liquid flow appeared with increasing biomass quantity. Rheological analysis revealed exponential increase of viscosity of the yeast floc suspension at the same biomass concentration of about 73 g/dm³ corresponding to 42.8% v/v of solid fraction. These facts have a particular importance for the successful processing of a high-celldensity airlift bioreactor as only a circulated flow regime will be favorable to keep the solid particles in suspension state and evenly distributed throughout the bioreactor.; União Europeia (UE). Marie Curie Fellowship of the European Community Programme - grant number HPMF-CT-2002-01643.

Application of a novel oscillatory flow micro-bioreactor to the production of γ-decalactone in a two immiscible liquid phase medium

Reis, N.; Gonçalves, C. N.; Aguedo, Mário; Gomes, Nelma; Teixeira, J. A.; Vicente, A. A.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em /04/2006 ENG
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A novel micro-bioreactor based on the oscillatory flow technology was applied to the scale-down of the biotechnological production of γ-decalactone. A decrease up to 50% of the time required to obtain the maximum concentration of the compound was observed, when compared with other scaled-down platforms (stirred tank bioreactor or shake flask). A three-fold increase in γ-decalactone productivity was obtained by increasing oscillatory mixing intensity from Reo ~482 to Reo ~1447. This was presumably related to the effective contribution of the reactor geometry to enhanced mass transfer rates between the two immiscible liquid phases involved in the process by increasing the interfacial area.; Fundação para a Ciência e a Tecnologia (FCT)

Proof-of-concept of a novel micro-bioreactor for fast development of industrial bioprocesses

Reis, N.; Gonçalves, C. N.; Vicente, A. A.; Teixeira, J. A.
Fonte: Wiley Periodicals Publicador: Wiley Periodicals
Tipo: Artigo de Revista Científica
Publicado em /11/2006 ENG
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37.26%
The experimental performance of a novel micro-bioreactor envisaged for parallel screening and development of industrial bioprocesses has been tested in this work. The micro-bioreactor with an internal volume of 4.5mL is operated under oscillatory flow mixing (OFM), where a controllable mixing and mass transfer rates are achieved under batch or continuous laminar flow conditions. Several batch fermentations with a flocculent Saccharomyces cerevisiae strain were carried out at initial glucose concentrations (S0) range of ~5–20 g/L and compared to yeast growth kinetics in a stirred tank (ST) bioreactor. Aerobic fermentations were monitored ex situ in terms of pH, DO, glucose consumption, and biomass and ethanol production (wherever applicable). An average biomass production increase of 83% was obtained in the micro-bioreactor when compared with the ST, with less 93.6% air requirements. It also corresponded to a 214% increase on biomass production when compared with growth in a shaken flask (SF) at S0=20 g/L. Further anaerobic fermentations at the same initial glucose concentration ranges gave the opportunity to use state-ofthe-art fiber optics technology for on-line and real-time monitoring of this bioprocess. Time profiles of biomass concentration (measured as optical density (OD))were very similar in the ST bioreactor and in the micro-bioreactor...

Removal of Cr(VI) from aqueous solutions by a bacterial biofilm supported on zeolite : optimisation of the operational conditions and scale-up of the bioreactor

Pazos, M.; Branco, Mónica; Neves, Isabel C.; Sanromán, M. A.; Tavares, M. T.
Fonte: John Wiley & Sons, Inc. Publicador: John Wiley & Sons, Inc.
Tipo: Artigo de Revista Científica
Publicado em /12/2010 POR
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The aim of this study was to investigate the feasibility of a bioreactor system and its scale-up to remove Cr(VI) from solution. The bioreactor is based on an innovative process that combines bioreduction of Cr(VI) to Cr(III) by the bacterium Arthrobacter viscosus and Cr(III) sorption by a specific zeolite. Batch studies were conducted in a laboratory-scale bioreactor, taking into account different operating conditions. Several variables, such as biomass concentration, pH and zeolite pre-treatment, were evaluated to increase removal efficiency. The obtained results suggest that the Cr removal efficiency is improved when the initial biomass concentration is approximately 5 g L–1 and the pH in the system is maintained at an acidic level. Under the optimised conditions, approximately 100 % of the Cr(VI) was removed. The scale-up of the developed biofilm process operating under the optimised conditions was satisfactorily tested in a 150-L bioreactor.; Xunta de Galicia - programa Angeles Alvariño

Biofabrication of customized bone grafts by combination of additive manufacturing and bioreactor knowhow

Costa, P. F.; Vaquette, C.; Baldwin, Jeremy; Chhaya, Mohit; Gomes, Manuela E.; Reis, R. L.; Theodoropoulos, Christina; Hutmacher, D. W.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Artigo de Revista Científica
Publicado em /05/2014 ENG
Relevância na Pesquisa
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This study reports on an original concept of additive manufacturing for the fabrication of tissue engineered constructs (TEC), offering the possibility of concomitantly manufacturing a customized scaffold and a bioreactor chamber to any size and shape. As a proof of concept towards the development of anatomically relevant TECs, this concept was utilized for the design and fabrication of a highly porous sheep tibia scaffold around which a bioreactor chamber of similar shape was simultaneously built. The morphology of the bioreactor/scaffold device was investigated by micro-computed tomography and scanning electron microscopy confirming the porous architecture of the sheep tibiae as opposed to the non-porous nature of the bioreactor chamber. Additionally, this study demonstrates that both the shape, as well as the inner architecture of the device can significantly impact the perfusion of fluid within the scaffold architecture. Indeed, fluid flow modelling revealed that this was of significant importance for controlling the nutrition flow pattern within the scaffold and the bioreactor chamber, avoiding the formation of stagnant flow regions detrimental for in vitro tissue development. The bioreactor/scaffold device was dynamically seeded with human primary osteoblasts and cultured under bi-directional perfusion for two and six weeks. Primary human osteoblasts were observed homogenously distributed throughout the scaffold...

Fungal fucoidanase production by solid-state fermentation in a rotating drum bioreactor using algal biomass as substrate

Rodríguez-Jasso, Rosa María; Mussatto, Solange I.; Sepúlveda, L.; Agrasar, A. T.; Pastrana, L.; Aguilar, C. N.; Teixeira, J. A.
Fonte: Institution of Chemical Engineers Publicador: Institution of Chemical Engineers
Tipo: Artigo de Revista Científica
Publicado em 01/01/2013 ENG
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Fucoidanase enzymes able to degrade fucoidan were produced by solid-state fermentation (SSF). The fermentation assays were initially carried out in a laboratory-scale rotating drum bioreactor, and two fungal strains (Aspergillus niger PSH and Mucor sp. 3P) and three algal substrates (untreated, autohydrolyzed, and microwave processed seaweed Fucus vesiculosus) were evaluated. Additionally, fermentations were carried out under rotational (10 rpm) and static conditions in order to determine the effect of the agitation on the enzyme production. Agitated experiments showed advantages in the induction of the enzyme when compared to the static ones. The conditions that promoted the maximum fucoidanase activity (3.82 U L−1) consisted in using Mucor sp. 3P as fungal strain, autohydrolyzed alga as substrate, and the rotational system. Such conditions were subsequently used in a 10 times larger scale rotating drum bioreactor. In this step, the effect of controlling the substrate moisture during the enzyme production by SSF was investigated. Moreover, assays combining the algal substrate with an inert support (synthetic fiber) were also carried out. Fermentation of the autohydrolyzed alga with the moisture content maintained at 80% during the fermentation with Mucor sp. 3P gave the highest enzyme activity (9.62 U L−1).

Biological treatment of a contaminated gaseous emission from a leather industry in a suspended-growth bioreactor

Carvalho, M.F.; Duque, A.F.; Moura, S.C.; Amorim, C.L.; Ferreira Jorge, R.M.; Castro, P.M.L
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2009 ENG
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A suspended-growth bioreactor (SGB) was operated for the treatment of a gaseous stream mimicking emissions generated at a leather industrial company. The main volatile organic compounds (VOCs) present in the gaseous stream consisted of 1-methoxy-2-propanol, 2,6-dimethyl-4-heptanone, 2-butoxyethanol, toluene and butylacetate. A microbial consortium able to degrade these VOCs was successfully enriched. A laboratory- scale SGB was established and operated for 210-d with an 8 h cycle period and with shutdowns at weekends. Along this period, the SGB was exposed to organic loads (OL) between 6.5 and 2.3 £ 102 g h¡1 m¡3. Most of the compounds were not detected at the outlet of the SGB. The highest total VOC removal efficiency (RE) (ca 99%) was observed when an OL of 1.6 £ 102 g h¡1 m¡3 was fed to the SGB. The maximum total VOC elimination capacity (1.8 £ 102 g h¡1 m¡3) was achieved when the OL applied to the SGB was 2.3 £ 102 g h¡1 m¡3. For all the operating conditions, the SGB showed high levels of degradation of toluene and butylacetate (RE t 100%). This study also revealed that recirculation of the gaseous effluent improved the performance of the SGB. Overall, the SGB was shown to be robust...

A membrane bioreactor for biotransformations of hydrophobic molecules using organic solvent nanofiltration (OSN) membranes

Valadez-Blanco, Rogelio; Ferreira, Frederico Castelo; Jorge, Ruben Ferreira; Livingston, Andrew Guy
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2008 ENG
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Thiswork reports the application of organic solvent nanofiltration (OSN) membranes to a membrane bioreactor for biotransformations (MBB). An organic solvent phasewas employed, allowing high substrate loadings and efficient product removal. The aqueous and organic phases were separated by an OSN membrane. The biotransformation of geraniol to R-citronellol by baker’s yeast was used as the model reaction, and n-hexadecane and toluene as the organic solvents. The performance of the MBB was compared to that of a direct contact biphasic (DCB) bioreactor. The MBB system resulted in lower productivities than the DCB system due to mass transfer limitations. For the n-hexadecane system, the membrane was the main mass transfer resistance, whereas for the toluene system the contribution of the aqueous liquid film mass transfer resistance became predominant. Further investigations are needed to improve the substrate transfer rates. Despite this, the MBB system prevented aqueous breakthrough, and thus the formation of two-phase emulsions. Toluene toxicity to the biocatalyst was also minimized, although it caused a reduction in the reaction enantiospecificity. This work showed that OSN-MBB systems avoid the formation of emulsions, thus reducing downstream separation and allowing increased substrate loadings.

Winery wastewater treatment : evaluation of the air micro-bubble bioreactor performance

Oliveira, Margarida; Duarte, E.
Fonte: InTech Publicador: InTech
Tipo: Parte de Livro
Publicado em //2011 ENG
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The wine sector has faced increasing pressure in order to fulfill the legal environmental requirements, maintaining a competitive position in a global market. The rising costs associated have stimulated the sector to seek sustainable management’s strategies, focussing on controlling the demand for water and improving its supply.Some EU Directives were implemented concerning water protection and management. These included in particular the Framework Directive in the field of water policy and environmental legislation about specific uses of water and discharges of substances.Several winery wastewater treatments are available, but the development of alternative technologies is essential to increase their efficiency and to decrease the investment and exploration costs.The main goals of the present paper are the comparison of different biological treatment systems, in particular fixed and suspended biomass, operating under aerobic conditions. Since the accurate design of the bioreactor is dependent on many operational parameters, aspects related to hydraulic retention time; oxygen mass transfer and contact time, energetic costs; sludge settling and production; response time during startup, flexibility and treated wastewater reuse...

Comparison between a conventional membrane bioreactor (C-MBR) and a biofilm membrane bioreactor (BF-MBR) for domestic wastewater treatment

Subtil,E. L.; Mierzwa,J. C.; Hespanhol,I.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2014 EN
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In this paper, the influence of biofilm carriers in a MBR on the performance of organic matter and nitrogen removal and the influence on membrane fouling were evaluated. The configurations studied included a Conventional Membrane Bioreactor (C-MBR) and a Biofilm Membrane Bioreactor (BF-MBR) operated in parallel, both fed with domestic wastewater. Regarding organic matter removal, no statistically significant differences were observed between C-MBR and BF-MBR, producing an effluent with a Soluble COD concentration of 27 ± 9.0 mgO2/L and 26 ±1.0 mgO2/L and BOD concentration of 6.0 ± 2.5 mgO2/L and 6.2 ± 2.1 mgO2/L, respectively. On the other hand, the BF-MBR produced a permeate with lower ammonia and total nitrogen concentrations, which resulted in a removal efficiency of 98% and 73%, respectively. It was also observed that the fouling rate was about 35% higher in the C-MBR than that for the BF-MBR, which also presented a reduction of total membrane resistance, about 29%, and increased operational cycle length around 7 days, compared to C-MBR.

Power consumption and mixing in a miniaturised bioreactor

Zhang, H.; Wang, W.; Fan, S.
Fonte: Taylor & Francis Ltd Publicador: Taylor & Francis Ltd
Tipo: Artigo de Revista Científica
Publicado em //2005 EN
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37.26%
Microbial fermentation plays an important role in digesting renewable biomass, in particular lignocellulose to generate new sources of chemical raw material and energy. The increasing number of genetic and process permutations during screening for process optimizations drives a strong demand for obtaining accurate biological and process data in short time frames and at low cost. A novel miniaturised bioreactor with a working volume of 7mL was fabricated to meet the requirements of fermentation process development. The engineering parameters including power consumption and mixing time were characterised and compared with those in a 7 L bioreactor with two standard Rushton impellers. Computational results in the 7L bioreactor were in good agreement with the literature and his approach was applied to this miniaturised bioreactor. Power number for the impellers used in the miniaturised reactor was found to vary with the detailed impeller geometrical characteristics, including the blade width, length and thickness. Mixing time in this miniaturised bioreactor was calculated to be around 0.2 s, shorter than the time required for metabolic regulations for some cells. This miniaturised bioreactor could dramatically change the fermentation process development.; Zhang...

Development of a Perfusion Bioreactor Strategy for Human Adipose-Derived Stem Cell Expansion

FLEMING, SARAH
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
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37.17%
Developing an optimized growth environment for adipose-derived stems cells (ASCs) to obtain clinically useable cell quantities from relatively small tissue biopsies would significantly impact the field of tissue engineering. To date, ASCs have been differentiated into adipose, bone, cartilage, smooth muscle, endothelial, skeletal muscle, nervous, and cardiac tissue. Therefore, ASCs have potential for use in the treatment of a wide variety of clinical conditions ranging from myocardial infarction, to musculoskeletal disorders, and the repair of soft tissue defects. In this work, a custom-designed, 3-dimensional (3-D) scaffold-based perfusion bioreactor system was investigated in the culture of ASCs. Decellularized adipose tissue (DAT) was used to provide a 3-dimensional scaffold, as it possesses the native extracellular matrix (ECM) architecture and composition of human adipose tissue. The DAT had a permeability of 149 m2, based on a perfusion rate of 1.5 mL/min over a 200 mg DAT sample, and the culturing medium was evenly perfused throughout the DAT, thereby permitting possible cell growth within the central regions. Initial culturing studies of human ASCs on tissue culture polystyrene (TCPS) demonstrated that hypoxic (5% O2) conditions decreased the doubling time...

Development of a sulfate reducing packed bed bioreactor for use in a sustainable hydrogen production process

McMahon, Matthew James Lee
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 1173524 bytes; application/pdf
EN; EN
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37.22%
A two-stage process is proposed that is based on the biological production of H2S from organic waste and its subsequent overall conversion to H2 via an exothermic reaction. The current study examined the first step of this process, namely, the design and operation of a packed bed bioreactor with high volumetric H2S production (mol/m3.d) and its comparison to analogous methanogenic technology. A novel method of inoculum design was developed by evaluating the kinetics and immobilization potential of Desulfovibrio desulfuricans (ATCC 7757) and a sulfate reducing bacteria (SRB) consortium. The consortium’s kinetics, as measured by the specific rate of sulfate reduction (1.2 g SO42-/g CDW.h), were approximately twice as fast as those of D. desulfuricans. The pure strain however exhibited superior immobilization potential. Studies revealed that a mixed inoculum containing 96 % D. desulfuricans and 4 % consortium facilitated the rapid immobilization of a highly active SRB biomass and contributed to improved bioreactor performance. Diatomaceous earth (DE) pellets, porous glass beads, polyurethane foam, and bone char were evaluated as potential carrier materials for SRB immobilization. The DE pellets immobilized the most biomass, were well suited for use at the industrial scale...

A laboratory simulation of in situ leachate treatment in semi-aerobic bioreactor landfill

Huo,Shou-liang; Xi,Bei-dou; Yu,Hai-chan; Fan,Shi-lei; Jing,Su; Liu,Hong-liang
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 EN
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In this study, two laboratory-scale simulated landfill bioreactors were established, of which Reactor A was operated only with leachate recirculation and served as the control, and Reactor B was operated as semi-aerobic bioreactor landfill with leachate recirculation. In situ leachate treatment and accelerating organic decomposition in semi-aerobic bioreactor landfill was investigated. The results indicated that the introduction of air into the landfill was favourable for optimising the micro-organism growth environment and accelerating the degradation of organic matter. It can be seen clearly from the results that NH4+-N can be removed in situ in the semi-aerobic bioreactor landfill with leachate recirculation. Moreover, semi-aerobic bioreactor landfill showed lower emissions for leachate than those in leachate from anaerobic landfill, with low concentrations of COD, VFA, NH4+-N and TKN, and which saved the disposing process of the discharged leachate. The three-dimensional excitation-emission matrix fluorescence spectroscopy (EEMs) of dissolved organic matter (DOM) in Reactor B changed greatly, and fluorescence peak changed from protein-like fluorescence at Day 60 to humic-like fluorescence at Day 95 and 250, while in Reactor A, fluorescence peak of DOM was always protein-like fluorescence. The comparison of the EEMs indicated that the semi-aerobic landfill accelerated the organic decomposition.