•Systematic/mechanistic modeling approach for bioreactor characterization is presented.•Gas transfer contributions from free surface and individual bubbles are decomposed.•The sensitivity of mass ...transfer around bubbles to local fluid mechanics is analyzed.•The approach can aid in digital scale up/down for two-phase bioreactors.
A mechanistic in-silico approach for predicting mixing and mass transfer in a two-phase stirred tank bioreactor is presented. This fully transient approach, which is tailored to run on GPUs, makes a direct appeal to first principles turbulence theory. We investigate various approaches for predicting the convective mass transfer coefficient around bubbles. We then validate the free surface and bubble mass transfer coefficients against measured data over a range of microbioreactor operating conditions and then link these variations to the underlying fluid mechanics. The approach is designed to be general and requires no re-tuning between operating conditions. Additionally, the presented approach can be utilized as a digital scaleup and tech-transfer strategy for bioreactors used in the biopharmaceutical industry.
Organ-on-a-chip systems are miniaturized microfluidic 3D human tissue and organ models designed to recapitulate the important biological and physiological parameters of their in vivo counterparts. ...They have recently emerged as a viable platform for personalized medicine and drug screening. These in vitro models, featuring biomimetic compositions, architectures, and functions, are expected to replace the conventional planar, static cell cultures and bridge the gap between the currently used preclinical animal models and the human body. Multiple organoid models may be further connected together through the microfluidics in a similar manner in which they are arranged in vivo, providing the capability to analyze multiorgan interactions. Although a wide variety of human organ-on-a-chip models have been created, there are limited efforts on the integration of multisensor systems. However, in situ continual measuring is critical in precise assessment of the microenvironment parameters and the dynamic responses of the organs to pharmaceutical compounds over extended periods of time. In addition, automated and noninvasive capability is strongly desired for long-term monitoring. Here, we report a fully integrated modular physical, biochemical, and optical sensing platform through a fluidics-routing breadboard, which operates organ-on-a-chip units in a continual, dynamic, and automated manner. We believe that this platform technology has paved a potential avenue to promote the performance of current organ-on-a-chip models in drug screening by integrating a multitude of real-time sensors to achieve automated in situ monitoring of biophysical and biochemical parameters.
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•A conceptual model of micro-capillary bioreactors degrading VOC vapors is presented.•Detailed mass transfer and biodegradation principles were incorporated in the model.•The model ...was validated with experiments over a broad range of operating conditions.•A sensitivity analysis provided deep insight into the functioning of the reactors.
Capillary microreactors have shown superior performance as a result of the precise control of reaction parameters, contact time, shape and size of the interface between gas and liquid and enhanced mass transfer due to high surface to volume ratio. In this work, a mathematical model of a capillary microbioreactor treating VOC vapors was developed and validated experimentally. The main goal for this conceptual model was to adequately describe or predict VOC vapor removal in the capillary microbioreactor under different operating conditions and its mineralization to CO2. The model considered toluene as the model VOC and included oxygen consumption and carbon dioxide production. Experimental data used for model calibration and validation were obtained from experiments conducted at various toluene and volumetric loading rates. A parametric sensitivity to the model was performed to identify the parameters that most affected the performance of the microbioreactor system. The most sensitive parameters were biokinetic parameters followed by system specific parameters, indicating that the system performance was limited by kinetics rather than by mass transfer. Overall, the model and the approach described herein help us better understand the performance and limits of these microbioreactors and they serve as important tools for process optimization.
It has long been known that the textile industry generates a massive amount of synthetic waste across the globe. Dye-containing wastewater is carcinogenic, mutagenic, recalcitrant, and xenobiotic. ...Several techniques have been developed for textile wastewater treatment. Most often, especially for dye-containing synthetic waste, bioremediation has now become one of the emerging techniques. Bioreactor, a common apparatus, whenever possible, may operate either continuously or in batches; has been extensively used for carrying out the hardest-to-meet biological reactions. The objective of this review is to emphasize a brief description of different bioreactors' performance, their features, and shortcoming. Special emphasis has been laid out on Membrane Bioreactor, Fluidized Bed Bioreactor, Moving Bed Bioreactor, Packed Bed Bioreactor, Airlift Bioreactor, Stirred Tank Bioreactor, Fixed Bed Bioreactor, and Rotating Biological Contactor. The key findings of each bioreactor's dye degradation performance have been reviewed. A brief discussion about recent trends in dye wastewater treatment has been depicted and based on the above facts future outlook is critically highlighted. A techno-economic assessment of bioremediation technology emphasizes its applicability for industrial scale. The review is expected to be beneficial to readers who are dealing with bioprocess, hybrid bioreactors, and designing bioreactors at a laboratory, pilot plant, and even on an industrial scale for the treatment of real textile waste. However, the selection criterion of a suitable bioreactor has relied on bioprocess engineering and economics. New technological advancements in the bioreactor have been discussed and Microbioreactor seems as a future outlook toward dye degradation.
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The present work reports the evaluation of the yield, productivity and operational stability of the chemoenzymatic oxidation of 2,5-furandicarboxaldehyde (DFF) to 2,5-furan ...dicarboxylic acid (FDCA) catalyzed by immobilized lipase B from Candida antarctica (Novozym® 435) in a continuous packed bed microbioreactor. The highest yields and productivities were achieved using a feed for the reaction medium at 36 µL/min flow. The yield and specific productivity in continuous packed bed microbioreactor were approximately 20% and 1000 times higher than that obtained by operating in millibioreactors. The operational stability of the biocatalyst in the microbioreactor was higher than that achieved in a millibioreactor in continuous operation for 24 h. Finally, the packed bed microbioreactor is an interesting and straightforward strategy to increase the stability of the biocatalyst in continuous mode.
A method where particulates are transferred
via
a cosmetic brush onto liquid drops created on a highly non-wetting substrate with a hole to generate talc and graphite liquid marbles (LMs) and ...talc-graphite Janus liquid marbles is described. van der Waals forces facilitated the attachment of particulates to the dry brush bristles. Subsequently, the surface tension forces that developed from particle interaction with water (which were
O
(10
2
) higher than the van der Waals forces) could then engender transfer of the particulates to the liquid-gas interface of the drop. Forces below 1 mN applied by a dangling foil on the LM ensured preservation of the drop shape when the force was removed. During the application of this force, the contact angles at the contact lines behaved differently from sessile drops that are inclined on surfaces. This preparation method portends the ability to automate the creation of LMs and Janus LMs for various applications.
Micro-capillary bioreactors (1 mm ID, 10 cm long) were investigated for the biodegradation of toluene vapors as a model volatile organic compound (VOC). The intended application is the removal of ...VOCs from indoor air, when such microbioreactor is coupled with a microconcentrator that intermittently delivers high concentrations of VOCs to the bioreactor for effective treatment. The effects of key operating conditions were investigated. Specifically, gas film and liquid film mass transfer coefficients were determined for different gas and liquid velocities. Both mass transfer coefficients increased with gas or liquid velocity, respectively, and the overall gas-liquid mass transfer was dominated by the liquid-side resistance. Experiments with the microbioreactors focused on the effects of gas velocity, liquid velocity and mineral medium renewal rate on the treatment of toluene vapors at different inlet concentrations. The best performance in terms of toluene removal and mineralization to CO2 was obtained when the gas and liquid velocity ratio was close to one and achieving Taylor or slug flow pattern. Sustained treatment over extended periods of time with toluene elimination capacities ranging from 4000 to over 9000 g m−3 h−1 were obtained, which is orders of magnitude greater than conventional biofilters and biotrickling filters. Biological limitations generally played a more important role than mass transfer limitation. Continuous mineral medium supply at a high rate (10 h liquid retention time) enabled pH control and provided ample nutrient supply and therefore resulted in better toluene elimination and mineralization. Overall, these studies helped select the most suitable conditions for high performance and sustained operation.
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•The operating conditions of microbioreactors degrading VOC vapor were characterized.•Liquid and gas velocity, VOC concentration and medium renewal were optimized.•Very high rates of toluene elimination were obtained (>4000 g m−3 h−1).•PH control and fast growing suspended bacteria was key to high performance.
Polycyclic aromatic hydrocarbons (PAHs) are pollutants of critical environmental and public health concern and their elimination from contaminated sites is significant for the environment. ...Biodegradation studies have demonstrated the ability of bacteria in biofilm conformation to enhance the biodegradation of pollutants. In this study, we used our newly developed microfluidic platform to explore biofilm development, properties, and applications of fluid flow, as a new technique for screening PAHs-degrading biofilms. The optimization and evaluation of the flow condition in the microchannels were performed through computational fluid dynamics (CFD). The formation of biofilms by PAHs-degrading bacteria Pseudomonas sp. P26 and Gordonia sp. H19, as pure cultures and co-culture, was obtained in the developed microchips. The removal efficiencies of acenaphthene, fluoranthene and pyrene were determined by HPLC. All the biofilms formed in the microchips removed all tested PAHs, with the higher removal percentages observed with the Pseudomonas sp. P26 biofilm (57.4% of acenaphthene, 40.9% of fluoranthene, and 28.9% of pyrene). Pseudomonas sp. P26 biofilm removed these compounds more efficiently than planktonic cultures. This work proved that the conformation of biofilms enhances the removal rate. It also provided a new tool to rapid and low-cost screen for effective pollutant-degrading biofilms.
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•A microfluidic device was developed to grow biofilms of Pseudomonas and Gordonia.•The microfluidic system was constructed based on computational fluid dynamics.•The microchip enables to screen PAHs' degrading capability at continuous flow.•Continuous flow and high shear stress in the microchip enhance biofilms formation.•Pseudomonas sp. P26 biofilm in the microdevice shows the highest PAHs removal.
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