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关键词： Cell culture   Cryopreservation   Bioreactors   Germplasm collections   Medicinal plant  

摘要： Cell suspension of a medicinal plant Polyscias filicifolia recovered after 5 years of cryopreservation in liquid nitrogen (- 196 degrees C) was cultured in 250 ml flasks and laboratory (20-l), pilot (75-l) and industrial (630-l) bioreactors operated under batch and semi-continuous regimes. Growth parameters of the recovered cell culture were compared to those recorded before cryopreservation and after 5 years of culture maintenance in the active collection with 2 weeks subculture intervals. The results revealed that cell viability, maximum accumulation of fresh and dry weights, specific growth rate and productivity on dry biomass in flasks and bioreactors of different types and volumes were not affected by cryopreservation. In 20-l bioreactors, longer lag phase was observed for cell culture maintained for 5 years by periodic subcultures compared to the initial and cryopreserved cell cultures, however, all differences in growth dynamics were mitigated during cultivation in 630-l bioreactors. This study demonstrates that cryopreservation is a reliable and effective method for conservation of P. filicifolia cell culture for biotechnological applications. Key message Cell suspension of a medicinal plant Polyscias filicifolia recovered after 5 years of cryopreservation fully retained its original growth and productivity when cultured in bioreactors from 20 to 630 l.

关键词： Leachate   OFMSW   Anaerobic membrane bioreactor   High-solid   Filtration performance  

摘要： The anaerobic digestion of leachate from organic fraction of municipal solid waste (OFMSW) is a long-standing challenge. A submerged anaerobic membrane bioreactor (AnMBR) embedding three flat sheet membrane was therefore continuously operated for 63 days to investigate the materials flow and membrane performance. The results obtained show that approximately 90% COD was removed and 86% was converted into methane under an OLR of 5.6 kgCOD/m3?d corresponding to a HRT of 10 days. Under the high solid condition (34.5?61.1 g/L total solids in AnMBR) and flux of 5 and 6 LMH, the membranes was operated practically at constant trans-membrane pressure (TMP). When the membrane was operated at a high flux of 7 LMH the TMP rapid increase occurred in 22 h resulting in a non-recoverable permeability. A sustainable flux was thus identified. This study demonstrated the feasibility of AnMBR treating OFMSW leachate under high solid condition with high flux.

关键词： Anaerobic moving bed bioreactorr   Aerobic membrane reactor   Real textile wastewater   Alphaproteobacteria   Silicon  

摘要： In this study, the treatability of real textile wastewater [dissolved organic carbon (DOC): 500 mg/L), color: 6383 Pt-Co, sulfate: 362 mg/L)] was investigated in sequential anaerobic moving bed bioreactor (AnMBBR) and aerobic membrane bioreactor (AeMBR). AnMBBR was filled with 40 % career material (Kaldnes K1). The effect of different hydraulic retention times (HRTs) (6-48 h) and powdered activated carbon (PAC) addition (1 g/L) was investigated for system optimization. Sequential AnMBBR- AeMBR was successfully operated for textile wastewater treatment corresponding to 92 %, and 90 % dissolved organic carbon (DOC) and color removals, respectively. The effluent quality, dropped under 45 Pt-Co and 18 mg/L effluent values, was relatively high and complianted with discharge standards. The Fourier transform infrared spectroscopy (FT-IR) analysis showed that primary amines are successfully removed in AeMBR effluent. Fouling in AeMBR was increased when HRT was reduced, however, improved by 90 % at PAC addition conditions. Except for soluble microbial products (SMP) and soluble extracellular polymeric substances (EPS), it was observed that silicon (Si) (13.16 %) has an important role in fouling which was confirmed by scanning electron microscopy (SEM) and Energy-Dispersive X-ray (EDX) analysis. Additionally, microbial community structures indicated that the membrane fouling can be caused by Alphaproteobacteria (80 %) which was the dominant culture in the biofilm layer at a maximum fouling rate.

关键词： Bioreactor   Denitrification   Biofilm   Electron donor  

摘要： A vertical baffled bioreactor (VBBR) was employed for tertiary denitrification. Its features were designed to minimize the demand for externally supplied electron donor by minimizing net biomass synthesis and oxygen respiration. Over a two-year period, complete denitrification was realized routinely in the VBBR. The nitrateremoval rate was proportion to the influent COD/N ratio, with complete denitrification possible for COD/N ratios >3 gCOD/gN. Batch kinetic tests carried out at the end of years 1 and 2 documented that supplied electron donor was oxidized in the first 1-2 h, but nitrate and nitrite reductions occurred predominantly after 2 h and were driven by internally stored electron donor. Measurements confirmed that the VBBR minimized the demand of added electron donor: The observed yield was only 0.05 mgVSS/mgCOD, and the COD demand for O2 respiration was only 1-6.7% of the COD demand for N reductions. Biofilm samples taken from the upper and lower ports in cylinder of VBBR had similarly high alpha diversity and dominant genera, but the upper biofilm had a denitrification rate about 70% greater than the lower biofilm. The higher denitrification rate in the upper biofilm correlated its higher content of active biomass.

关键词： Gaseous VOC purification   Fluidized bed bioreactor   Packing material  

摘要： Gas-phase fluidized-beds reactor (FBR) can overcome the shortages of bed clogging and performance decline in packed-bed reactors on VOCs treatment. Ideal FBR packing materials with minimum fluidized velocity and surface characteristics are required. In this study, an expanded polystyrene (EPS) with particle size 1.0-2.0 mm was selected as the skeleton among six types of EPS and two types of expanded polypropylene (EPP). They were then physically coated with a combination of potato dextrose medium, fine wheat bran particles, and inorganic glue. Different glue concentrations and amounts of medium were tested and the optimal values of 2 % and 0.22 ***(-2) were achieved. The wheat-coated EPS obtained hydrophilic functional groups on the surface, and its contact angle decreased from 93 degrees to 37 degrees after coating. By scanning electronic microscopy, more microorganisms were observed on the surface of the coated EPS than that of the uncoated EPS. A lab-scale fluidized bioreactor was built to treat gaseous ethanol. The minimum fluidized velocity of coated packing materials was 0.2 m.s(-1) under a relative humidity of 50 +/- 10 %, reaching an average elimination capacity of 681 g m(-3) h(-1) during the 28-days operation, while the bioreactor packed with uncoated EPS reached only 18 g m(-3) h(-1). (c) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

关键词： Nitrogen metabolism   Sludge reduction   Metagenomic sequencing   Nitrospira   Dissimilatory nitrate reduction  

摘要： Synchronous sludge reduction and nitrogen removal have attracted increasing attention, while the underlying mechanisms of diverse nitrogen metabolism within the complicated processes remain unclear. Four anoxic/oxic membrane bioreactors, three of which were upgraded by anaerobic side-stream reactors (ASSR) and carriers (APSSR-MBRs), were operated to determine effects of hydraulic retention time of ASSRs. APSSR-MBRs achieved more significant nitrogen removal and higher nitrate uptake rate because of more denitrifying bacteria and the supernumerary release of secondary substrates. Ammonia uptake rate showed the diverse Nitrospira preceded over anaerobic decay and sulfide inhibition in the ASSR, and made the reactor exhibit higher nitrification capacity. Metagenomic analysis indicated that APSSR-MBRs showed higher abundances of genes related to nitrogen consumption processes, and higher abundances on the carriers, confirming their pivotal roles in nitrogen metabolism. This study provided novel perspectives to build a bridge between process model and nitrogen metabolism in the sludge reduction system..

关键词： Osmotic membrane bioreactor   Bioelectrochemical system   Reverse solute transport   Draw solute concentration   Salinity accumulation  

摘要： A suitable draw solute (DS) concentration in bioelectrochemically assisted osmotic membrane bioreactor (BEA-OMBR) can convert the "negative effect" of salinity accumulation into a "beneficial effect" by using the reverse-fluxed DS as a buffer agent or a carbon source supplement. Herein, the effect of DS concentration from acid buffer solution (i.e., ammonium chloride, NH4Cl), alkaline buffer solution (i.e., sodium bicarbonate, NaHCO3), and organic solution (i.e., sodium acetate, NaOAc) on salinity accumulation was systematically investigated. Salinity accumulation with NaHCO3 DS mainly derived from reversal fluxed sodium ion (Na+, major contributor with DS concentration <= 0.25 M) and bicarbonate ion (main contributor with DS concentration <= 0.50 M): Na+ accumulation could be mitigated by Na+ transport dominant by electrically driven migration (i.e., 21.3-62.1% of reverse-fluxed Na+), and bicarbonate accumulation could be reduced by buffer system. A medium-low concentration of 0.25 M NH4Cl DS had a better performance on current density of 165.0 +/- 23.0 A m(-3) and COD removal efficiency of 91.5 +/- 3.4% by taking advantage that 77.7 +/- 1.3% of reverse-fluxed ammonium could be removed by biological treatment and ammonium transport. A high NaOAc DS concentration (i.e., <= 0.05 M) exhibited a higher current density of 145.3-146.0 A m(-3) but a lower COD removal efficiency due to the limited carbon source utilization capacity of anaerobic bacteria. Both concentration diffusion (20.9-28.3%) and electrically driven migration (29.5-39.4%) promoted reverse-fluxed Na+ transport to catholyte and thus mitigated Na+ accumulation in the feed/anolyte. These findings have provided an optimal DS concentration for BEA-OMBR operation and thus encourage its further development. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： Near-infrared spectroscopy   Wastewater analyses   Wastewater treatment   Membrane bioreactor   Soluble microbial products   Extracellular polymeric substances  

摘要： The use of near-infrared (NIR) spectroscopy in wastewater treatment has continuously expanded. As an alternative to conventional analytical methods for monitoring constituents in wastewater treatment processes, the use of NIR spectroscopy is considered to be cost-effective and less time-consuming. NIR spectroscopy does not distort the measured sample in any way as no prior treatment is required, making it a waste-free technique. On the negative side, one has to be very well versed with chemometric techniques to interpret the results. In this study, filtered and centrifuged wastewater and sludge samples from a lab-scale membrane bioreactor (MBR) were analysed. Two analytical methods (conventional and NIR spectroscopy) were used to determine and compare major wastewater constituents. Particular attention was paid to soluble microbial products (SMPs) and extracellular polymeric substances (EPSs) known to promote membrane fouling. The parameters measured by NIR spectroscopy were analysed and processed with partial least squares regression (PLSR) and artificial neural networks (ANN) models to assess whether the evaluated wastewater constituents can be monitored by NIR spectroscopy. Very good results were obtained with PLSR models, except for the determination of SMP, making the model qualitative rather than quantitative for their monitoring. ANN showed better performance in terms of correlation of NIR spectra with all measured parameters, resulting in correlation coefficients higher than 0.97 for training, testing, and validation in most cases. Based on the results of this research, the combination of NIR spectra and chemometric modelling offers advantages over conventional analytical methods. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： bioreactor   biphasic mixture equations   nutrient transport   scaffold   tissue engineering  

摘要： A mathematical model is developed for fluid flow, nutrient transport, and cell growth inside a bioreactor with a scaffold at the periphery and lumen at the centerline. The scaffold material is assumed to be deformable. In order to deal with the deformation of the solid phase and fluid phase inside the scaffold, biphasic mixture theory equations are adopted, which are derived from the theory of mixtures. The flow inside the lumen is governed by Stokes equation. Advection-diffusion-reaction equation is used for the mass balance of the nutrient within the scaffold region. Cell growth depends on the nutrient concentration and is expressed by the Contois equation that accounts for contact inhibition. We use lubrication approximation to reduce the system of hydrodynamic and nutrient transport equations. This leads to a coupled system of partial differential equations (PDEs) with time-dependent variables. Laplace transformation is used to deal with time-dependent terms, and Durbin's algorithm is used to retrieve the time dependency. We investigate the outreach of nutrients inside the scaffold region, which regulates the growth of cells at a particular time. Based on the available experimental data, we consider relevant reaction kinematics of the cells and observe the corresponding nutrient distribution inside the bioreactor. The factors that affect the nutrient concentration are lumen radius, porosity, and permeability of the scaffold, Thiele modulus, pressure gradient, and so forth. The total mass transfer rate is computed to understand the nutrient distribution across various regions of the bioreactor.

关键词： Bioprocess development   Automation   Stirred-tank bioreactors   Escherichia coli   Protein expression  

摘要： Automation, parallelization and autonomous operation of standard lab equipment, usually applied for manual bioprocess development, is considered as the key for reduction of bioprocess development time and costs. An automated bioreactor system with 4 stirred-tank bioreactors on a L-scale was combined with a custom-made biomass transfer system to distribute the cell suspensions produced on the L-scale into 48 parallel stirred-tank bioreactors on a mL-scale. Afterwards parallel protein expression studies automated by a liquid handling system with integrated fluorescence reader were performed. Isopropyl beta-D-1-thiogalactopyranoside-induced (IPTG) expression of the red fluorescence protein mCherry was studied as an example of using fed-batch processes with recombinant Escherichia coli. In a first automated study, IPTG concentrations were varied in 48 parallel fed-batch processes with E. coli cells produced at a growth rate of 0.1 h-1 on an L-scale and transferred automatically to the mL-scale. The mCherry expression rate increased with increasing inducer concentration until the highest protein expression rate was observed at > 9 mu M IPTG. In a second automated study, the growth rate of E. coli was varied between 0.1- 0.2 h-1 in parallelly-operated stirred-tank bioreactors on a L-scale. The cells were automatically transferred and distributed into the stirred-tank bioreactors on a mL-scale and the concentration of the inducer IPTG was varied as before in parallel fed-batch processes. An increased growth rate during the production of the recombinant E. coli cells and/or higher cell densities during protein expression resulted in the increased IPTG concentrations necessary to achieve identical expression rates compared to a growth rate of 0.1 h-1 with the exception of very low inducer concentrations and inducer concentrations in excess. The new automated multiscale cascade of parallel stirred-tank bioreactors should easily be applicable for performing fast optimisation s