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关键词： Bone tissue engineering   Finite element modeling   Fluid flow dynamics   Osteoblasts   Oxygen   Perfusion bioreactor   3D-printed scaffold  

摘要： Fluid flow dynamics and oxygen-concentration in 3D-printed scaffolds within perfusion bioreactors are sensitive to controllable bioreactor parameters such as inlet flow rate. Here we aimed to determine fluid flow dynamics, oxygen-concentration, and cell proliferation and distribution in 3D-printed scaffolds as a result of different inlet flow rates of perfusion bioreactors using experiments and finite element modeling. Pre-osteoblasts were treated with 1 h pulsating fluid flow with low (0.8 Pa;PFFlow) or high peak shear stress (6.5 Pa;PFFhigh), and nitric oxide (NO) production was measured to validate shear stress sensitivity. Computational analysis was performed to determine fluid flow between 3D-scaffold-strands at three inlet flow rates (0.02, 0.1, 0.5 ml/min) during 5 days. MC3T3-E1 pre-osteoblast proliferation, matrix production, and oxygen-consumption in response to fluid flow in 3D-printed scaffolds inside a perfusion bioreactor were experimentally assessed. PFFhigh more strongly stimulated NO production by pre-osteoblasts than PFFlow. 3D-simulation demonstrated that dependent on inlet flow rate, fluid velocity reached a maximum (50-1200 mu m/s) between scaffold-strands, and fluid shear stress (0.5 4 mPa) and wall shear stress (0.5 20 mPa) on scaffold-strands surfaces. At all inlet flow rates, gauge fluid pressure and oxygen-concentration were similar. The simulated cell proliferation and distribution, and oxygen-concentration data were in good agreement with the experimental results. In conclusion, varying a perfusion bioreactor's inlet flow rate locally affects fluid velocity, fluid shear stress, and wall shear stress inside 3D-printed scaffolds, but not gauge fluid pressure, and oxygen-concentration, which seems crucial for optimized bone tissue engineering strategies using bioreactors, scaffolds, and cells.

关键词： air consumption   CFD   double-deck flat sheet MBR   fouling control   slug bubble formation and reformation  

摘要： Slug bubbling in single deck flat sheet membrane bioreactor (FSMBR) is effective in controlling membrane fouling. Here the primary focus is on the employment of the slug bubbling method, with its more economical air consumption, to a double-deck large-scale FSMBR with 100 membrane plates on each deck. The analysis of a new design concept shows that sufficient hydrodynamic effect could be induced by a novel economical three-stage slug aeration process of formation-breakup-reformation. Computational fluid dynamics simulation was applied to examine both the development of the slug bubble and especially its reformation. It was found that the combination of a gap between two decks of 400 mm with an air velocity of 16 m/s was an optimal condition to achieve good hydrodynamic conditions in both decks. The corresponding SAD(m)is 0.098 Nm(3)m(-2)hr(-1), which is a reduction of 66% compared to the most advanced single deck FSMBR.

关键词： Organic material   Helminth eggs   Permeate flow   Fouling   Backwashing  

摘要： A pilot-scale anaerobic dynamic membrane bioreactor (AnDMBR) was monitored at ambient temperature to assess domestic sewage treatment from a housing development. The dynamic membrane (DM) was developed from polypropylene support material with an average opening of 90 nm, inside an external configuration module. To minimize energy costs, the AnDMBR system was operated under hydraulic pressure, in two Cycles, without backwashing (Cycle 1), and with backwashing (Cycle 2). The HRT was 18 h and the initial permeate flow was 780 L m(-2) h(-1). The CRT of Cycle 1 was 91 d, and Cycle 2 was 49 d. The average concentrations of MLTSS in Cycle 1 and 2 were 29.40 and 29.60 g L-1, respectively. The system achieved good average efficiency of removing organic matter, with a total COD value of 86.0% and soluble COD of 76.0%, being able to remove 91.0% of suspended solids, producing an effluent with low turbidity (18.0 NTU). The results also show that the DM contributed to the production of effluent with a concentration of helminth eggs which meets WHO recommendations [47] for unrestricted irrigation. A significant amount of biogas was produced by the system and most came out in dissolved form with the effluent due to supersaturation. The average transmembrane pressure (TMP) of Cycle 2 was 2.0 times greater than that of Cycle 1, which suggests that fouling cannot be effectively removed with tap-water washing or with backwashing.

关键词： Wastewater treatment   Optimization   RSM-CCD   Kinetics   Chlorella pyrenoidosa   Biomass production   Bioremediation  

摘要： Tertiary wastewater treatment by microalgae has been focused on various researches due to its immense potential of remediating toxic pollutants and the production of valuable biomass. The treatment efficiency is greatly influenced by environmental parameters. In the present work, response surface methodology has been employed to predict the optimum conditions of temperature, pH, and photoperiod for maximizing biomass production and nutrient removal efficiency. The optimum conditions have been calculated as 20.65 degrees C temperature, pH 7.72, and 15.69 h photoperiod. Under the optimum conditions, 5.36 g L-1 of biomass concentration, 98.72% of ammonium nitrogen, and 76.29% of phosphate phosphorus removal efficiency has been obtained by conducting in 2 L Erlenmeyer flask. Various sigmoidal growth and substrate removal kinetic models such as logistic, Gompertz, modified Luedeking-Piret model, biomass dependent, and independent substrate removal kinetic models were used to simulate the growth and substrate removal kinetics of microalgae. These models were compared using the coefficient of regression (R-2), adjusted R-2 (Adj. R-2), second-order Akaike information criterion, and root mean square error. By comparing the statistical data, it was concluded that the logistic growth model and Luedeking-Piret substrate removal model provided a better fit for the experimental data. Both these models confirmed that the substrate removal by microalgae from wastewater is directly linked to the biomass concentration of the growth of microalgae.

关键词： bioaugmentation   biostimulation   dissimilatory nitrate reduction to ammonium   denitrification   woodchip bioreactor  

摘要： Aims This study was done to obtain denitrifiers that could be used for bioaugmentation in woodchip bioreactors to remove nitrate from agricultural subsurface drainage water. Methods and Results We isolated denitrifiers from four different bioreactors in Minnesota, and characterized the strains by measuring their denitrification rates and analysing their whole genomes. A total of 206 bacteria were isolated from woodchips and thick biofilms (bioslimes) that formed in the bioreactors, 76 of which were able to reduce nitrate at 15 degrees C. Among those, nine potential denitrifying strains were identified, all of which were isolated from the woodchip samples. Although many nitrate-reducing strains were isolated from the bioslime samples, none were categorized as denitrifiers but instead as carrying out dissimilatory nitrate reduction to ammonium. Conclusions Among the denitrifiers confirmed by N-15 stable isotope analysis and genome analysis, Cellulomonas cellasea strain WB94 and Microvirgula aerodenitrificans strain BE2.4 appear to be promising for bioreactor bioaugmentation due to their potential for both aerobic and anaerobic denitrification, and the ability of strain WB94 to degrade cellulose. Significance and Impact of the Study Denitrifiers isolated in this study could be useful for bioaugmentation application to enhance nitrate removal in woodchip bioreactors.

关键词： biomanufacturing   bioprocessing   Chinese hamster ovary (CHO) cell culture   critical quality attribute (CQA)   monoclonal antibody (mAb)   mycoplasma   partial least squares (PLS) regression   principal component analysis (PCA)  

摘要： A mycoplasma contamination event in a biomanufacturing facility can result in costly cleanups and potential drug shortages. Mycoplasma may survive in mammalian cell cultures with only subtle changes to the culture and penetrate the standard 0.2-mu m filters used in the clarification of harvested cell culture fluid. Previously, we reported a study regarding the ability of Mycoplasma arginini to persist in a single-use, perfusion rocking bioreactor system containing a Chinese hamster ovary (CHO) DG44 cell line expressing a model monoclonal immunoglobulin G 1 (IgG1) antibody. Our previous work showed that M. arginini affects CHO cell growth profile, viability, nutrient consumption, oxygen use, and waste production at varying timepoints after M. arginini introduction to the culture. Careful evaluation of certain identified process parameters over time may be used to indicate mycoplasma contamination in CHO cell cultures in a bioreactor before detection from a traditional method. In this report, we studied the changes in the IgG1 product quality produced by CHO cells considered to be induced by the M. arginini contamination events. We observed changes in critical quality attributes correlated with the duration of contamination, including increased acidic charge variants and high mannose species, which were further modeled using principal component analysis to explore the relationships among M. arginini contamination, CHO cell growth and metabolites, and IgG1 product quality attributes. Finally, partial least square models using NIR spectral data were used to establish predictions of high levels (>= 10(4) colony-forming unit [CFU/ml]) of M. arginini contamination, but prediction of levels below 10(4) CFU/ml were not reliable. Contamination of CHO cells with M. arginini resulted in significant reduction of antibody product quality, highlighting the importance of rapid microbiological testing and mycoplasma testing during particularly long upstream bioprocesses to ensure pr

关键词： Anthraquinone dyes   Entrapment   Column bioreactor   Phytotoxicity   LCMS Q-TOF  

摘要： Myco-valorization (Myco-Valtn) concept was explored using Myrothecium verrucaria ITCC-8447 via column bioreactor to remove two anthraquinone (ARq) dyes. Among the three myco-valtn approaches free cell dependent enabled more than 80% removal of Anthraquinone violet R (AVR) and Alizarin cyanine green (ACG) after 48 h at 30 +/- 2 degrees C. Enzymatic treatment removed more than 50% AVR and ACG after 10 min. However, synthetic and natural support entrapment on Scotch-Brite (R) (SB) and Luffa cylindrica (LC) enabled more than 80% removal in SB-ACG and LC-ACG and more than 60% in SB-AVR and LC-AVR in 6th cycle. The regenerated column enhanced the removal of dye and allowed the column to run for multiple cycles. Further after FTIR XRD and LCMS Q-TOF, analysis it was observed that ACG and AVR were completely degraded and laccase played the key roles in the degradation of ACG and AVR and the degraded metabolites of anthraquinone dyes (ACG and AVR) exhibited much less toxicity than the parent dye using phytotoxicity assays.

关键词： dynamic membrane   hollow fiber   membrane bioreactor   municipal wastewater treatment   support material  

摘要： BACKGROUND Membrane bioreactor (MBR) applications have been limited by high cost of membrane modules and fouling problems. Dynamic membrane (DM) technology can be a solution for these problems. Low-cost filters can be used as support materials for dynamic (cake) layer formation. The characteristics of support material play an important role on dynamic layer formation behavior. Therefore, the aim of this study was to investigate the impact of support material type on dynamic membrane bioreactor (DMBR) performance for municipal wastewater treatment. Hollow fiber support materials, made of polyester fabrics and glass fiber materials, were used for DM formation. RESULTS Similar treatment performances were obtained with each membrane achieving high removal efficiencies for chemical oxygen demand (>97%) and total suspended solids (>99%) parameters. Higher transmembrane pressure (TMP) was observed for glass fiber material in comparison to polyester material. Based on morphological analyses, dynamic layers formed on both support materials had similar composition, organic and inorganic materials. A homogeneous layer was formed on polyester support material, while fine particles were deposited between the filaments of glass fiber support material, which caused clogging. CONCLUSION Based on TMP results and morphological analyses, polyester support material provided better formation of DM layer. Thus selection of proper support material type is very important to achieve stable DM layer in DMBRs. (c) 2020 Society of Chemical Industry

关键词： Bioreactors   Brine denitrification   Nitrates   Citrus woodchip   Soil pollution   Carbon media  

摘要： Increasing knowledge of nitrate removal using denitrifying bioreactors has illustrated the usefulness of this management practice for treating discharge water from agricultural land uses. The objective of this study was to assess the viability of almond shell, chopped carob, olive bone, and citrus woodchip as carbon media for denitrification of brine with high nitrate load (EC approximate to 20 dS m(-1), NO3--N concentration approximate to 65-80 mg NO3--N L-1) in bioreactors. To the authors' knowledge, this is the first test of denitrifying brine using organic wastes as the carbon substrate, and the first use of these carbon media for that purpose. Nitrate removal efficiency and efficiency:cost ratio were considered. The results indicated that the best removal efficiency and cheapest cost were provided by citrus woodchip (3.02 +/- 0.15 mg NO3--N m(-3)d(-1)) at a cost of approximate to 6euro m(-3), followed by almond shell (1.54 +/- 0.20 mg NO3--N m(-3)d(-1)) at a cost of approximate to 19euro m(-3). Chopped carob and olive bone showed negligible nitrate removal in the brine;chopped carob generated acidic leachate with extremely high dissolved organic carbon, and olive bone resulted in a highly saline leachate. Of the four media tested, the results of this study indicated that citrus woodchip was the most suitable media for denitrification of the brine.

关键词： anaerobic membrane bioreactor   membrane fouling   biogas sparging flow   membrane autopsy and particulate size distrubiton  

摘要： Membrane fouling behaviors were investigated to different biogas sparging flows such as 0.5, 1.0, and 1.5 L biogas/min for anaerobic submerged membrane bioreactor (AnSMBR) treating synthetic wastewater in a laboratory-scale. For each different biogas flow rate, the membrane module of the same feature was used in the system and the effect of biogas sparging flow on fouling control was examined in the process. Surface area of the used membrane module was selected as 162.6 cm(2). The sprarging biogas was supplied from the gas formed in reactor system. Treatment parameters were analyzed in the process of reactor operation. Also, a series of analysis, including soluble microbial products (SMP), extracellular polymeric substances (EPSs), scanning electron microscopy, energy dispersive X-ray spectroscopy, particle size distribution, and filtration resistances were performed by considering the membrane module. The AnSMBR accomplished COD removal efficiencies between 95 and 98%. Total organic carbon and sulfate concentration in permeate were found in the range of 25-56 and 90-200 mg/L, and 96-98 and 38-65% in removal percentage;respectively. TSS and VSS concentrations in permeate were less than 10 mg/L that means removal efficiencies of 98%. Methane production rate in the system was determined of 0.35 +/- 0.08 LCH4/g COD removed. The results showed that differences between COD and TOC removals were negligible at different biogas sparging flows. The priority of biogas sparging flows in terms of providing high permeate fluxes were found to be 1.5 L biogas/min > 1.0 L biogas/min > 0.5 L biogas/min. The same order was found with the fluxes in terms of both SMP and EPS within cake formed on the fibers in membrane module. Studying results showed that biogas sparging flow increasing was found to effective on membrane fouling controls. It has been determined that sparging gas at an optimum flow rate (1.0 L biogas/min) can be effective in controlling membrane fouling.