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关键词： Photocatalysis   Membrane bioreactor   Textile dye   Continuous reactor  

摘要： A pilot-scale photocatalytic membrane bioreactor (PMBR) was developed for the treatment of textile dyeing wastewater. The PMBR is made of mild steel rectangular reactor of photocatalytic unit and polyethersulphone submerged hollow fibre membrane bioreactor unit with the working volume of about 20 L. For easy recovery, the tungsten oxide (WO3) and WO3/1% graphene oxide (GO)-powdered photocatalyst were made into bead and immersed in photocatalytic reactor. Graphene oxide incorporation has shown better results in decolourisation and degradation when compared with WO3 alginate alone. The incorporation of GO into WO3 minimises the recombination of photogenerated electron-hole pairs. The operating conditions such as 3 h of contact time for photocatalysis reaction (WO3/1% GO), 10 h hydraulic retention time for MBR and 100 kPa of transmembrane pressure were optimised. Chemical oxygen demand removal efficiency of 48% was attained with photocatalysis, and the removal efficiency was further increased up to 76% when integrated with MBR. The colour removal efficiency after photocatalysis was 25% further increased up to 70% with MBR. Complete total suspended solid removal has been achieved with this hybrid system.

关键词： Grau second order model   Modified Stover-Kincannon model   Anaerobic reactor configuration   Chemical oxygen demand   Biological inferences   Kinetic parameters   Biochemical oxygen demand  

摘要： In this study, the treatment of poultry slaughterhouse wastewater (PSW) was evaluated using two new down-flow high-rate anaerobic bioreactor systems (HRABS), including the down-flow expanded granular bed reactor (DEGBR) and the static granular bed reactor (SGBR). These two bioreactors have demonstrated a good performance for the treatment of PSW with removal percentages of the biochemical oxygen demand (BOD5), the chemical oxygen demand (COD), and fats, oil, and grease (FOG) exceeding 95% during peak performance days. This performance of down-flow HRABS appears as a breakthrough in the field of anaerobic treatment of medium to high-strength wastewater because down-flow anaerobic bioreactors have been neglected for the high-rate anaerobic treatment of such wastewater due to the success of up-flow anaerobic reactors such as the UASB and the EGSB as a result of the granulation of a consortium of anaerobic bacteria required for efficient anaerobic digestion and biogas production. Hence, to promote the recourse to such technologies and provide further explanation to their performance, this study approached the kinetic analysis of these two down-flow HRABS using the modified Stover-Kincannon and the Grau second-order multi-component substrate models. From a comparison between the two models investigated, the modified Stover-Kincannon model provided the best prediction for the concentration of the substrate in the effluent from the two HRABS. This analysis led to the determination of the kinetic parameters of the two models that can be used for the design of the two HRABS and the prediction of the performance of the SGBR and DEGBR. The kinetic parameters determined using the Modified Stover-Kincannon were Umax = 40.5 gCOD/*** and K-B = 47.3 gCOD/*** for the DEGBR and U-max = 33.6 gCOD/*** and K-B = 44.9 gCOD/*** for the SGBR;while, using the Grau second-order model, the kinetic models determined were a = 0.058 and b = 1.112 for the DEGBR and a = 0.135 and b = 1.33

关键词： Data-driven model   Performance prediction   Membrane bioreactor   Model comparison   Gradient boosting regression   Data feature analysis  

摘要： Complex hydrodynamic conditions and the dynamic process of multi-habitats have brought challenges for the real-time management of novel wastewater treatment techniques. Thus, based on a well-performing membrane bioreactor with internal circulation, this paper presented an intelligent data mining work of performance prediction and the analysis of data influence for efficient management. The experimental data with 440 samples and nine internal environment parameters were integrated, and the concentrations of COD, NH4+-N and total nitrogen (TN) in the effluent were used as multiple performance indicators. Then, a comprehensive testing was utilized for recognizing the most robust model from the deep neural network, regression tree, random forest, adaptive boosting and gradient boosting regression (GBR), which included the evaluations of model fitting and generalization ability. Furthermore, the feature relative importance (Imp) and principal component analysis (PCA) was applied to analyze the influence of data. The results indicated that the GBR model had a higher performance, in which, the R squared scores of 5-fold cross-validation were 0.847, 0.792 and 0.851 in predicting the concentration of COD, NH4+-N and TN, respectively. Besides, the quantification of Imp was accorded with the independent result of PCA, which indicated that the GBR model had well captured the dynamic information.

关键词： CHO cells   Scale-down   Dissolved oxygen gradients   Mixing time   Scale-up  

摘要： Scale-down simulators have been widely applied to investigate the impact of various concentration gradients on the efficiency of industrial-scale fed-batch biopmcesses involving microbial cell factories. However, due to the general fragility and shear sensitivity of mammalian cells, these simulators, especially those with multiple compartments, have not been widely adopted to investigate the effects of similar concentration gradients on cell culture processes. In this work, we developed a multi-compartment scale-down simulator comprising a stirred tank bioreactor and a plug-flow reactor (PFR). CHO cells expressing a recombinant protein were recycled through the PFR whilst being subjected to dissolved oxygen gradients at varying residence times from 70 s to 120 s. The results show a clear cut switch in the metabolism of CHO cells, such that until a residence time of 90s was exceeded, the cells did not respond to the presence of dissolved oxygen gradients in the PFR. Beyond this residence time threshold, there was a marked accumulation of lactate and up to 15 % decline in viable cell density in the stationary phase, compared to the reference fed-batch process. Interestingly, the recombinant protein productivity was not affected by the dissolved oxygen gradients, although the purity of the product, measured as the concentration of host cell proteins in the supernatant was adversely affected. The response time threshold in the metabolism of the cells was used to propose a scale-up technique based on similar physiological indices between bioreactor scales. The demonstrated method is a possible tool for assessing the suitability of a process in a given large scale bioreactor with known mixing times.

关键词： Pomegranate juice   Pectinase immobilization   Polyaldehyde polysaccharide   Continuous operation   Packed bed reactor  

摘要： In this study, the glutaraldehyde, polyaldehyde pullulan and polyaldehyde kefiran were applied to immobilize the pectinase on the silanized glass bead and then a packed bed reactor (PBR) was used to continuous clarification process of the pomegranate juice. The results showed that the bioreactor packed with the enzymes immobilized by all three cross-linkers had the best performance at the temperature of 50 degrees C, a flow rate of 0.5 mL/min and treatment time of 42 min. After the clarification process, the turbidity of the pomegranate juice was significantly decreased from similar to 70.2 to similar to 17.4 NTU and the clarity of the samples was increased from similar to 81.15 to similar to 96.13%. The findings showed the clarification process had a significant effect on the pomegranate juice properties so that the total titratable acidity, reducing sugar content and lightness parameter were increased while pH, total soluble solids, viscosity, total phenol content and radical scavenging activity of the juice samples was decreased by this process. Finally, it must be stated that the bioreactor packed with polyaldehyde kefiran-immobilized pectinase had the best performance in the clarification of pomegranate juice due to the higher capacity of this cross-linker in the pectinase immobilization.

关键词： scaffold   perfusion bioreactor   collagen   apatite nanoparticles   magnesium   human mesenchymal stem cell   osteogenesis  

摘要： In bone tissue engineering, the design of 3D systems capable of recreating composition, architecture and micromechanical environment of the native extracellular matrix (ECM) is still a challenge. While perfusion bioreactors have been proposed as potential tool to apply biomechanical stimuli, its use has been limited to a low number of biomaterials. In this work, we propose the culture of human mesenchymal stem cells (hMSC) in biomimetic mineralized recombinant collagen scaffolds with a perfusion bioreactor to simultaneously provide biochemical and biophysical cues guiding stem cell fate. The scaffolds were fabricated by mineralization of recombinant collagen in the presence of magnesium (***). The organic matrix was homogeneously mineralized with apatite nanocrystals, similar in composition to those found in bone. X-Ray microtomography images revealed isotropic porous structure with optimum porosity for cell ingrowth. In fact, an optimal cell repopulation through the entire scaffolds was obtained after 1 day of dynamic seeding in the bioreactor. Remarkably, *** scaffolds exhibited higher cell viability and a clear trend of up-regulation of osteogenic genes than control (non-mineralized) scaffolds. Results demonstrate the potential of the combination of biomimetic mineralization of recombinant collagen in presence of magnesium and dynamic culture of hMSC as a promising strategy to closely mimic bone ECM.

关键词： Ganoderma applanatum   exopolysaccharide   endopolysaccharide   zebrafish   toxicology  

摘要： Natural mycelial exopolysaccharide (EPS) and endopolysaccharide (ENS) extracted from bioreactor-cultivated European Ganoderma applanatum mushrooms are of potential high commercial value for both food and adjacent biopharmaceutical industries. In order to evaluate their potential toxicity for aquaculture application, both EPS (0.01-10 mg/mL) and ENS (0.01-10 mg/mL) extracts were tested for Zebrafish Embryo Toxicity (ZFET);early development effects on Zebrafish Embryos (ZE) were also analyzed between 24 and 120 h post-fertilization (HPF). Both EPS and ENS are considered non-toxic with LC50 of 1.41 mg/mL and 0.87 mg/mL respectively. Both EPS and ENS did not delay hatching and teratogenic defect towards ZE with <1.0 mg/mL, respectively. No significant changes in the ZE heart rate were detected following treatment with the two compounds tested (EPS: 0.01-10 mg/mL: 176.44 +/- 0.77 beats/min and ENS: 0.01-10 mg/mL: 148.44 +/- 17.75 beats/min) compared to normal ZE (120-180 beats/min). These initial findings support future pre-clinical trials in adult fish models with view to safely using EPS and ENS as potential feed supplements for supplements for development of the aquaculture industry.

关键词： Single-use bioreactor   St. John's-Wort   Root culture   Medicinal plants   Bioactive compounds  

摘要： Bioreactors are widely used for industrial production of therapeutic products. In this study, a disposable bubble column bioreactor made from flexible plastic films and cheap accessories was developed and its applicability for plant root culture was tested. Hypericum perforatum adventitious roots were cultivated in a set of 15, 30, and 60-L bioreactors for a four weeks period and 14.4, 11, and 10 g dry roots per liter were harvested respectively. Appropriate air flow pattern caused the roots to distribute to more than 70 % of the liquid culture volume without using any support matrix. The packing densities showed 30 % variation at different location of root biomass. Determination of hypericins, total phenols, and total flavonoids indicated some variation throughout the bioreactor, however, the average of them resembled the roots cultivated in flasks. Appropriate bioreactors remain an obstacle in commercialization of plant root cultures and the developed bioreactor seems appropriate for mass production of some adventitious and hairy roots in a modular design.

关键词： Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)   RecombinantB   megaterium   Fed-batch fermentation   Oxygen transfer   Copolymer  

摘要： Polyhydroxyalkanoates (PHAs) are biodegradable polyesters accumulated in a wide variety of microorganisms as intracellular carbon and energy storage compounds. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is one of the most valuable biopolymers because of its superior mechanical properties. Here, we developed a bioprocess utilizing recombinantBacillus megateriumstrain for PHBV over-production from glucose, without any precursor addition. PHA production was performed in a controlled bioreactor by batch and fed-batch modes using wild-typeB. megateriumand rec-B. megateriumcells overexpressing the nativephaCgene. The effect of oxygen transfer rate on biomass formation and PHA accumulation was also investigated, under different dissolved oxygen levels. Structural and thermal properties of PHA were characterized by GC-FID,H-1-NMR, TGA and DSC analyses. Significantly, the copolymer produced from glucose as the carbon source in rec-B. megateriumwas composed of 58 mol% of 3-hydroxyvalerate monomers. After 66 h, rec-B. megateriumcells in fed-batch fermentation with a pre-determined growth rate mu(0) = 0.1 h(-1)produced the highest CDW (7.7 g L-1) and PHA concentration (6.1 g L-1). Moreover, an exponential glucose feeding profile resulted in 2.2-fold increase in PHA yield compared to batch cultivation. Overall, this study paves the way to an enhanced biopolymer production process inB. megateriumcells, where the highest product yield on cell was obtained asY(P/X) = 0.8 g g(-1).

关键词： Packed-bed bioreactor   Solid-state fermentation   Aspergillus niger   Heat and mass transfer model   Two-phase model   O-2 uptake rate  

摘要： Model-based strategies for scaling up traditional packed-bed bioreactors used in solid-state fermentation have been available for over two decades. However, these strategies are theoretical, not being based on experimental data. A recently proposed strategy did use experimental data;however, it was based on data from a slow-growing fungus and also considered heat transfer in both the axial and radial directions, ignoring the fact that radial heat transfer is negligible in large-scale packed-bed bioreactors. The current work demonstrates a scale-up strategy based on a model describing heat transfer only in the axial direction. The strategy is demonstrated for the cultivation of Aspergillus niger, a fast-growing filamentous fungus. In the model, the kinetics of production of metabolic heat are based on an experimental time-course profile for the O-2 uptake rate. The model is validated by comparing its predictions for temperature profiles in the bed with temperatures measured experimentally in a pilot-scale bioreactor. Finally, the validated model is used to explore strategies for optimizing the performance of large-scale traditional packed-bed bioreactors. We conclude that a key strategy is to decrease the temperature of the inlet air during periods of peak heat generation.