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Abstract.--Microalgae photobioreactors are among the most effective systems for capturing gaseous C[O.sub.2], the main contributor to global warming. Their capacity to generate massive amounts of biomass has been exploited serendipitously [...]

Problem statement: This study discussed the problem of accumulation of Zn and Cu in the topsoil as a result of application of mineral feed additives that possess low bioavailability in animal diet. The review considered the production process of mineral feed additives in which a product supplies microelements in highly bioavailable form. Enrichment of natural biomass of edible microalgae with microelement metal ions, which supply microelements of feeding significance in livestock diet, is considered in term of sustainable production. Approach: Production of microalgae-derived products as mineral feed additives requires elaboration of the processes for cultivation of alga, enrichment process and afterwards recovery of the enriched biomass from the solution to obtain liquid free of cells that could be reused in the next process. In this study membrane bioreactor was considered as a method for separation, both in photobioreactor (growth of microorganism) as well as in the enrichment process. Results: Effort involved in thermal and chemical separation techniques is higher than that in mechanical techniques. Membrane bioreactors which are usually applied to treat wastewater, both industrial and domestic. This study discussed method to separate a valuable biomass of enriched microalgae and reuse the solution with residual metal ions that can be used once again in the subsequent biosorption process. Conclusion/Recommendation: Taking into consideration care about the environment it is better to apply membrane modules in the production process in terms of sustainable production. The proposed solution assumed the application of membrane modules as a separation step after enrichment process and biomass recovery. Key words: Microalgae, mineral feed additives, biosorption, bioaccumulation, microelements, membrane bioreactors, INTRODUCTION Each process in food and agriculture industry has an impact on the environment and there is much concern about environmental pollution (1). The intensification of agricultural production in Poland [...]

Problem Statement: Mixing filamentous fungi entails delicate balance between promoting high volumetric oxygen transfer coefficient ([k.sub.L]a) while keeping low hydrodynamic stresses in the microenvironment of cultures. This study examined the oxygen transfer capability of a prototype low shear helical impeller as a potential replacement for the standard Rushton turbine. Approach: The dependence of [k.sub.L]a upon specific power uptake, superficial gas velocity and apparent viscosity were examined under coalescent, non-coalescent and viscous pseudoplastic fluids scenario using dynamic gassing out technique. Subsequently, collected data were treated under historical data design of response surface methodology. Results: Three empirical power law [k.sub.L]a correlations were developed for each fluid. Correlation comparison with literature models for single turbine agitation suggest higher [k.sub.L]a augmentation within 1.5-3.6 folds for helical impeller in distilled water and as high as 78% improvement in electrolytes fluid. However impeller performance is comparatively 10% lower against theoretical [k.sub.L]a of triple turbines arrangement for power uptake between 0-1600 W [m.sup.-3]. In case of carboxymethylcellulose, better oxygen transfer is expected for design with higher proportionality of impeller-to-tank internal diameter. Conclusions: Helical impeller performance as gas-liquid contactor is comparable to single and triple Rushtons turbines, with superficial gas velocity proved to be more influential than power uptake in non-viscous liquids and vice versa in viscous pseudoplastic fluids. Key words: oxygen transfer, impeller, stirred tank bioreactor, response surface methodology, INTRODUCTION Solubilization of oxygen in liquid medium constitutes one of the decisive factors leading to the success of fermentation processes. More often than not, wholly oxygenation of vessel would be [...]

Recently a cartilage growth finite element model (CGFEM) was developed to solve non-homogeneous and time-dependent growth boundary-value problems (Davol et al., 2008, 'A Nonlinear Finite Element Model of Cartilage Growth,' Biomech. Model. Mechanobiol., 7, pp. 295-307). The CGFEM allows distinct stress constitutive equations and growth laws for the major components of the solid matrix, collagens and proteoglycans. The objective of the current work was to simulate in vitro growth of articular cartilage explants in a steady-state permeation bioreactor in order to obtain results that aid experimental design. The steady-state permeation protocol induces different types of mechanical stimuli. When the specimen is initially homogeneous, it directly induces homogeneous permeation velocities and indirectly induces nonhomogeneous solid matrix shear stresses; consequently, the steady-state permeation protocol is a good candidate for exploring two competing hypotheses for the growth laws. The analysis protocols were implemented through the alternating interaction of the two CGFEM components: poroelastic finite element analysis (FEA) using ABAQUS and a finite element growth routine using MATLAB. The CGFEM simulated 12 days of growth for immature bovine articular cartilage explants subjected to two competing hypotheses for the growth laws: one that is triggered by permeation velocity and the other by maximum shear stress. The results provide predictions for geometric, biomechanical, and biochemical parameters of grown tissue specimens that may be experimentally measured and, consequently, suggest key biomechanical measures to analyze as pilot experiments are performed. The combined approach of CGFEM analysis and pilot experiments may lead to the refinement of actual experimental protocols and a better understanding of in vitro growth of articular cartilage. [DOI: 10.1115/1.3049856] Keywords: growth, cartilage, mixture, permeation, bioreactor, finite element analysis

Microchannel bioreactors have applications for manipulating and investigating the fluid microenvironment on cell growth and functions in either single culture or co-culture. This study considers two different types of cells distributed randomly as a co-culture at the base of a microchannel bioreactor: absorption cells, which only consume species based on the Michaelis-Menten process, and release cells, which secrete species, assuming zeroth order reaction, to support the absorption cells. The species concentrations at the co-culture cell base are computed from a three-dimensional numerical flow-model incorporating mass transport. Combined dimensionless parameters are proposed for the co-culture system, developed from a simplified analysis under the condition of decreasing axial-concentration. The numerical results of species concentration at the co-culture cell-base are approximately correlated by the combined parameters under the condition of positive flux-parameter. Based on the correlated results, the critical value of the inlet concentration is determined, which depends on the effective microchannel length. For the flow to develop to the critical inlet concentration, an upstream length consisting only of release cells is needed; this upstream length is determined from an analytical solution. The generalized results may find applications in analyzing the mass transport requirements in a co-culture microchannel bioreactor. [DOI: 10.1115/1.2720913] Keywords: microchannel bioreactor, co-culture cell growth, species concentration

Microchannel bioreactors have been used in many studies to manipulate and investigate the fluid microenvironment around cells. In this study, substrate concentrations and shear stresses at the base were computed from a three-dimensional numerical flow-model incorporating mass transport. Combined dimensionless parameters were developed from a simplified analysis. The numerical results of substrate concentration were well correlated by the combined parameters. The generalized results may find applications in design analysis of microchannel bioreactors. The mass transport and shear stress were related in a generalized result. Based on the generalized results and the condition of dynamic similarity, various means to isolate their respective effects on cells were considered. [DOI: 10.1115/1.2170118] Keywords: microchannel bioreactor, cell culture, substrate concentration, shear stress

An Escherichia coli cell-free expression system is encapsulated in a phospholipid vesicle to build a cell-like bioreactor. Large unilamellar vesicles containing extracts are produced in an oil-extract emulsion. To form a bilayer the vesicles are transferred into a feeding solution that contains ribonucleotides and amino acids. Transcription-translation of plasmid genes is isolated in the vesicles. Whereas in bulk solution expression of enhanced GFP stops after 2 h, inside the vesicle permeability of the membrane to the feeding solution prolongs the expression for up to 5 h. To solve the energy and material limitations and increase the capacity of the reactor, the [alpha]-hemolysin pore protein from Staphylococcus aureus is expressed inside the vesicle to create a selective permeability for nutrients. The reactor can then sustain expression for up to 4 days with a protein production of 30 [micro]M after 4 days. Oxygen diffusion and osmotic pressure are critical parameters to maintain expression and avoid vesicle burst. [alpha]-hemolysin | cell-free protein expression | membrane-anchoring polypeptide

Advanced bioreactors are essential for meeting the complex requirements of in vitro engineering functional skeletal tissues. To address this need, we have developed a computer controlled bench-top bioreactor system with capability to apply complex concurrent mechanical strains to three-dimensional matrices independently housed in 24 reactor vessels, in conjunction with enhanced environmental and fluidic control. We demonstrate the potential of this new system to address needs in tissue engineering, specifically toward the development of a tissue engineered anterior cruciate ligament from human bone-marrow stromal cells (hBMSC), where complex mechanical and biochemical environment control is essential to tissue function. Well-controlled mechanical strains (resolution of < 0.1 [micro]m for translational and < 0.1[degrees] for rotational strain) and dissolved oxygen tension (between 0%-95% [+ or -] 1%) could be applied to the developing tissue, while maintaining temperature at 37 +/-0.2[degrees]C about developing tissue over prolonged periods of operation. A total of 48 reactor vessels containing cell culture medium and silk fiber matrices were run for up to 21 days under 90[degrees] rotational and 2 mm translational deformations at 0.0167 Hz with only one succumbing to contamination due to a leak at an medium outlet port. Twenty-four silk fiber matrices seeded with human bone marrow stromal cells (hBMSCs) housed within reactor vessels were maintained at constant temperature (37+/-0.2[degrees]C), pH (7.44+/-0.02), and p[O.sub.2] (20+/-0.5%) over 14 days in culture. The system supported cell spreading and growth on the silk fiber matrices based on SEM characterization, as well as the differentiation of the cells into ligament-like cells and tissue (Altman et al., 2001). [DOI: 10.1115/1.1519280]

Biofilm reactors have been used to investigate lead adsorption in aquatic environments because they allow analyses of the complex interactions of lead in complete biological systems. Herein, an integrated model describing the behavior of lead in oligotrophic freshwater aquatic environments is investigated with a laboratory biofilm reactor system. The results suggest that adsorption of lead to aquatic systems is much higher than has been previously reported.

Anaerobic bioreactor systems were utilized to establish the mechanism of the microbial biodegradation of Aroclor 1248-spiked sediment, with a sanitary landfill leachate as a novel nutrient, carbon and microbial source. Average total chlorine and biphenyl of the original sample was reduced by 11% and 23%, respectively, after 13 weeks, with majority of the dechlorination occurring within seven weeks. These results show that the use of anaerobic bioreactor system is a promising technology for environmental bioremediation.

Higher amounts of trichloroethylene (TCE) were removed from the lumen of methanotrophic bacteria, Methylosinus trichosporium OB3b, inside a hollow fiber membrane bioreactor at hydraulic residence times of 5-9 min in the lumen than at hydraulic residence times of 3-15 min in the lumen and shell. Rapid biodegradation was observed when TCE was transferred to the shell, with 75% of the transferred TCE achieving complete biodegradation. These results suggest that a hollow fiber membrane reactor system coupled with a mutant strain of the methanotrophic bacteria could be an effective method for biodegradation.

The biodegradation of methanotrophic trichloroethylene in a two-stage bioreactor system was investigated. The results showed that more than 90% of the trichloroethylene was removed in less than 4.5 hours during the single-pass operation while 93% was removed in under 6 hours of plug-flow residence during cross-flow operation. Biomass and trichloroethylene concentrations determined the rate of degradation.

The enhancement of the effectiveness of bioremediation technologies for treating creosote and pentachlorophenol contaminated groundwater by using specially selected microorganisms is discussed. Bench and pilot scale evaluations were conducted on the performance of the bioreactors on the basis mass balance evaluations of chemical analyses of bioreactor influent, effluent, residues, comparative biological toxicity and tetratogenicity measurements. The capability and potential of bioreactor technologies were demonstrated.

Byline: M. Vieira, A.G. Brito, R. Nogueira This study aimed to investigate the effects of carbon availability and intermittent aeration on nitrogen removal in a Sequencing Batch Biofilm Reactor (SBBR). The percentage of nitrogen removal in the SBBRs operating with dump fill and slow fill with optimum intermittent aeration was quite similar, 75.7% and 69.2%, respectively, indicating that intermittent aeration allowed a considerable energy saving without compromising significantly nitrogen removal. Accumulation of storage polymers by heterotrophic bacteria was only observed in the dump fill mode of operation. FISH analyses of the biofilm indicated that ammonia-oxidisers belonged to the beta-subclass Proteobacteria and nitrite-oxidisers were affiliated with the genus Nitrospira.

Byline: Hai-Lou Xu, Shao Bing Johanan Aow, Jing Wei Samuel Chua, Yu Liu The bacterial diversity and their population changes were investigated in acetate-fed aerobic granules cultivated in two Sequencing Batch Reactors (SBRs), A and B. The top nine dominant bacteria were isolated, and their growths were tracked in another two SBRs (C and D) which were cultivating granules without selection pressures. The nine bacterial population in C and D were compared to the references obtained from A and B. The failure to cultivate granules in C and D was attributed to the nine isolates being outcompeted by poor settling fast growing bacteria and failing to reach a critical population size.

Byline: Weili Zhou, Tsuyoshi Imai, Masao Ukita Thermophilic granulation processes were examined with synthetic wastewaters and were compared with the parallel mesophilic ones. The results indicated that granules could be formed well under compatible thermophilic surroundings in both carbohydrate- and protein-rich substrates. Compared with the mesophilic process, thermophilic granulation took relatively longer time, but thermophilic UASB reactors had much higher treatment capacity and efficiency than the mesophilic ones. Under the same running conditions, thermophilic sludge had lower contents of Extracellular Polymer (ECP) than mesophilic ones, which might be one of the reasons of the longer period needed for thermophilic granulation.

Byline: Puspendu Bhunia, M.M. Ghangrekar This paper researches on the development of a dimensionless number for predicting percentage granulation in Upflow Anaerobic Sludge Blanket (UASB) reactors for treating biodegradable wastewaters. A Biomass Granulation Index (BGI) has been framed based on the experimental work conducted using laboratory scale UASB reactors. This index depends on mixing in the sludge bed, induced due to biogas and superficial upflow velocity of wastewater in UASB reactors. For obtaining proper granulation (percentage granules greater than 50%) resulting in higher Chemical Oxygen Demand (COD) removal efficiency, this paper recommends to design UASB reactors with BGI in the range of 240-560.

Byline: Claudio Di Iaconi, Guido Del Moro, Antonio Lopez, Roberto Ramadori The paper reports the results of a laboratory-scale investigation aimed at evaluating the influence of the filling material of a Sequencing Submerged Biofilter Reactor (SSBR) on granular biomass generation. The results showed that aerobic granular biomass generation was obtained only in the reactor filled with kmt-k1 carrier, since the features of this filling media are such that they generate a bed characterised by rather uniform internal and external small-sized pore volumes able to retain the released biofilm particles. Finally, the aerobic granule formation improved the biomass retention efficiency and reduced the excess sludge production.

Byline: Zhi-Hua Li, Takahiro Kuba, Tetsuya Kusuda, Xiao-Chang Wang Two different feeding lengths were applied to control the granule size. It was found that the size of granules was considerably controlled in R2 (60 min for feeding). However, the settleability in R2 was not as good as that in R1 (12 min for feeding). However, this approach of controlling the granule size also loosens the structure concerning on the difference between SVI5 and SVI30, which might lead to instability in the long term. Based on the observation of the ash-solids fraction of biomass, it was confirmed that frequent update of granules mainly happened on the surface of granules.

A laboratory experiment where students simulate acid mine drainage remediation by creating their own bioreactors is described. This experiment teaches students about environmental chemistry as well as data interpretation.

Researchers at National Institute of Standards and Technology (NIST), Gaithersburg, Md., and University of Colorado Boulder (CU) developed a prototype bioreactor--a device for culturing cells to create engineered tissues--that both [...]