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关键词： Bioethanol   Column bioreactor   Combined bioreactor   Repeated-batch fermentation   Stirred tank bioreactor   Very high gravity fermentation  

摘要： A stirred tank bioreactor (STR) coupled with two column bioreactors (CRs) was used for ethanol production from sweet sorghum stem juice by Saccharomyces cerevisiae SSJ01KKU in a very high gravity fermentation. The effects of the medium circulation rate between the STR and CRs (2.6 and 5.2 mL/min, corresponding to 25 and 50 % of the S. cerevisiae specific growth rate), the starting time of medium circulation (0 and 4 h) and cell inoculation were investigated. The results showed that a medium circulation rate of 5.2 mL/min, starting the medium circulation at the beginning of fermentation (0 h) with cell inoculation into the STR only were appropriate conditions for ethanol production. This yielded an average ethanol concentration (PE) of 120.96 g/L and ethanol productivity (QP) of 2.52 g/L.h. When a repeated-batch (RB) ethanol fermentation in the STR coupled with CR was carried out using a drain and fill technique at different volumes (75 and 90 %, referenced as RB1 and RB2, respectively), it was found that at least eight successive cycles could be operated under both RB1 and RB2. The average PE and QP for RB1 and RB2 were not significantly different. However, the average total ethanol production rate in RB2 (3.25 g/h) over the eight cycles was significantly higher than that of RB1 (2.60 g/h).

关键词： Single-use bioreactors (SUBs)   Coupled CFD-species transport-PBM   QMOM   Hydrodynamics   Mass (O 2 ) transfer  

摘要： In this study, Euler-Euler coupled computational fluid dynamics (CFD), species transport and population balance model (PBM) simulations have been used to model multiphase hydrodynamics and mass (O2) transfer in a single use bioreactor (SUB) for mAb production. In simulations, drag was estimated by Schiller-Neuman equations. O2(g) local volume fraction was estimated via species transport model (STM). The PBM equations were solved using quadrature method of moments (QMOM) to get bubble size distribution (BSD) and thereby the Sauter mean diameter,d32. Also, the mean diameter over surface (d21) and De Brouckere mean (d43) were estimated for calculation of the BSD. The mass transfer coefficient (kLa) was predicted using species transport model (STM) and Higbie?s penetration theory. The experimental estimation of kLa was performed via simplified dynamic pressure method. Total stress (?) and energy dissipation rate (?) were estimated as 34.17 Pa and 1.352 m2.s- 3, respectively. Calculations of the d32, d21 and d43 indicate that the BSD becomes more dispersed with increase in agitation speed at all aeration rates. Further, the kLa values of STM were within 0.47% to 4.21% of experimental data. In summary, with error between 4 and 10%, the proposed approach offers better visualization of O2 transport mechanism across gas?liquid interface than conventional approaches.

关键词： Sclerotium rolfsii   Scleroglucan   Practical yield   Operative conditions   EPS properties  

摘要： Exopolysaccharide (EPS) secretion by Sclerotium rolfsii ATCC 201126 in submerged cultures, already identified as high-osmolarity responsive, was assessed by reducing C-source without compromising EPS yields. A designed medium with 80 g sucrose L-1 (MOPT80) was tested at 3 L-bioreactor scale at different temperature, agitation, aeration and pH (uncontrolled vs. controlled) values. Optimal operative conditions (200 rpm, 28 degrees C, 0.5 vvm and initial pH -pH(i)- 4.5) were validated, as well as the possibility to work at pH(i) 5.5 to reduce biomass production. Purified EPSs produced in MOPT80 at optimal and other valid operative conditions exhibited refined grade (<1 % proteins and ash, 3-4 % reducing sugars, 87-99 % total sugars). EPS purity, M-W and rheological parameters led to discourage pH controlled at 4.5. Relatively constant M-W (6-8 x 10(6) Da) and outstanding viscosifying ability were found. Polyphasic EPS analysis (titre, purity, macromolecular features and rheological fitness) would support to properly select production conditions.

关键词： Airlift   Bubble dynamics   Level set method   Biorefineries   Microalgae  

摘要： Coupled level set and CFD (computational fluid dynamics) methods are adopted in this work to track the moving gas?liquid interfaces in the riser of an external loop airlift photobioreactor (ALR) in which microalgae are used to produce biofuels and capture CO2 from flue-gas. Modeling the behavior of gas bubbles is a crucial aspect for the fine-tuning of the operation of the reactor when inserted into a closed-loop biorefinery at the pilot-scale. The experimental data used for simulation were completely acquired or calculated from hydrodynamic experimental campaigns carried out on the ALRs. The rise, coalescence, and shape dynamics of the bubbles of the flue-gas are simulated in a rectangular domain representing the vertical section of the ALR riser. Different correction approaches, such as the conservative level set method (CLSM), are proposed to face the volume loss characteristic of LSM. Computational results evidenced strong agreement with the experimental data (bubble shapes and trajectories). The physically-based CLSM model was then effectively used for the fine-tuning of the multiphase flow regime inside the ALRs, suggesting operating conditions for the outdoor cultivation with Reynolds number = 10000 ? 11000, Sherwood number between 1400 and 1800, and spherical-caps bubbles in the upper half of the riser, mildly churning the microalgae while avoiding damages to their cells.

关键词： IFAS-MBR configuration   Cost-coupled LCA analysis   Optimization   Sustainable development  

摘要： A rising need to design the wastewater treatment configurations with the uppermost economic and environmental compatibility is felt thanks to the increasing trend of water dilemma all over the universe. In light of this subject, the present study for the first time manifests a comprehensive cost-coupled life cycle assessment data of a highly efficient optimized integrated fixed-film activated sludge-membrane bioreactor (IFAS-MBR) configuration. For this purpose, a broad range of analyses was conducted comprising greenhouse gas emission, energy demand, economic burden, and sensitivity analysis regarding the optimization approach. The maximum removal efficiency at optimum condition was as follows: COD (94.54%), BOD (99.86%), TN (97%), TSS (99.99%), and total carbon (93.45%). From an environmental perspective, climate change dominantly emanated from greenhouse gases emission (27.5%) with the most impact on human health (67.57%). The configuration used an 8.27 MJ energy derived from fossil fuels utilization. However, the IFAS unit played a key role in carbon footprint, dominantly associated with CO2 emission (86.4%). The construction expenditures of IFAS and MBR units illustrated the maximum economic burdens (87.3%). Accordingly, this study can present a stepwise guideline for further related investigations. (c) 2021 Elsevier Ltd. All rights reserved. Superscript/Subscript Available

摘要： Perkinsus marinus is a marine protozoan responsible for "Dermo" disease in the eastern oyster species, Crassostrea virginica. P. marinus has been detected along the Atlantic Coast of the United States and Mexico. In laboratory studies, many parasites need to be maintained in vivo, which complicates the study of the organism. However, In vitro cell culture for P. marinus at a scale of 1 mL was established in 1993 by several groups with the 1995 optimization (Gauthier & Vasta, 1993, 1995) considered the gold standard for small scale growth of this species. In addition to its importance as a parasite of an important food source, P. marinus is notable among easily cultured microbes in its ability to produce, fold and excrete very large, complex proteins. Such proteins could potentially be used for therapeutic applications, such as development of vaccines. In order to be useful as an organism to produce vaccines, we need to learn how to grow the organism at larger scale. Transitioning the growth procedures from small culture vials to tenfold larger bioreactors is a first step towards achieving this scale up. Growing P. marinus in a bioreactor introduces new production variables and challenges, such as: aeration, pH control, temperature control, and cost of media. In this study we developed methods and procedures to grow P. marinus in bioreactors and have also developed a lower cost growth medium that reduced the cost of growth medium ingredients by about 60%. Higher order cell culture comes with expensive media components, most notably fetal bovine serum (FBS), which provides essential growth factors and cytokines for growing cells. A promising replacement for FBS was found to be chicken serum (CS). It has the potential to provide growth factors and cytokines at a much lower cost than FBS. SuperPro Designer v10 (Intelligen, Inc., Scotch Plains, New Jersey) is a process simulator software designed to analyze the techno-economics of commercial-scale bioprocesses. SuperPro

关键词： biotherapeutics   cellulose hydrogels   encapsulation   gut microbiota   hydrogel bioreactors   probiotic bacteria  

摘要： The current perspective presents an outlook on developing gut-like bioreactors with immobilized probiotic bacteria using cellulose hydrogels. The innovative concept of using hydrogels to simulate the human gut environment by generating and maintaining pH and oxygen gradients in the gut-like bioreactors is discussed. Fundamentally, this approach presents novel methods of production as well as delivery of multiple strains of probiotics using bioreactors. The relevant existing synthesis methods of cellulose hydrogels are discussed for producing porous hydrogels. Harvesting methods of multiple strains are discussed in the context of encapsulation of probiotic bacteria immobilized on cellulose hydrogels. Furthermore, we also discuss recent advances in using cellulose hydrogels for encapsulation of probiotic bacteria. This perspective also highlights the mechanism of probiotic protection by cellulose hydrogels. Such novel gut-like hydrogel bioreactors will have the potential to simulate the human gut ecosystem in the laboratory and stimulate new research on gut microbiota.

关键词： Biohydrogen production   Dark fermentation   Molasses   Preheating treatment  

摘要： This study investigated the effects of substrate concentration, HRT (hydraulic retention time), and pre-treatment of the substrate molasses on biohydrogen production from waste molasses (condensed molasses fermentation solubles, CMS) with a CSTR (continuously-stirred tank reactor). First, the hydrogen production was performed with various CMS concentrations (40-90 g COD/L, total sugar 8.7-22.6 g/L) with 6 h HRT. The results show that the maximal hydrogen production rate (HPR) occurred at 80 g COD/L substrate (19.8 g ToSu/L, ToSu: Total Sugar), obtaining an HPR of 0.417 mol/L/d. However, maximum hydrogen yield (HY) of 1.44 mol H-2/mol hexose and overall hydrogen production efficiency (HPE) of 25.6% were achieved with a CMS concentration of 70 g COD/L (17.3 g ToSu/L). The substrate inhibition occurred when CMS concentration was increased to 90 g COD/L (22.6 g ToSu/L). Furthermore, it was observed that the optimal HPR, HY, and HPE all occurred at HRT 6 h. Operating at a lower HRT of 4 h decreased the hydrogen production performance because of lower substrate utilization efficiency. The employment of pre-heating treatment (60 degrees C for 1 h) of the substrate could markedly enhance the fermentation performance. With 6 h HRT and substrate pre-heating treatment, the HPE raised to 29.9%, which is 18% higher than that obtained without thermal pretreatment. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Membrane bioreactor   Calcium   Powdered activated carbon   Toxicity   Trihalomethanes  

摘要： This study investigated the effect of powdered activated carbon and calcium on trihalomethane toxicity in zebrafish embryos and larvae in hybrid membrane bioreactors. Two hybrid membrane bioreactors were configured with the addition of powdered activated carbon or calcium to reduce the trihalomethane formation potential. Trihalomethane formation decreased by approximately 37.2% and 30.3% in membrane bioreactorpowdered activated carbon and membrane bioreactor-calcium, respectively. Additionally, the toxic effect of trihalomethane formation was examined on zebrafish embryos and larvae. About 35% of the embryos exposed to trihalomethanes (800 ppb) showed signs of deformation, with the majority displaying coagulation within 24 h after exposure. Color preference tests, which were conducted to identify any abnormal activities of the embryos, showed an increase in preference from short to longer wavelengths upon exposure to high levels of trihalomethanes. This may indicate damage to the optical organs in zebrafish when exposed to trihalomethanes. Behavioral analysis showed reduced mobility of zebrafish larvae under different trihalomethane concentrations, indicating a decrease in the average activity time with an increasing trihalomethane concentration. The membrane bioreactor effluents were toxic to zebrafish embryos and larvae in the presence of high trihalomethane concentrations. To understand the mechanism behind trihalomethane toxicity, further studies are needed.

关键词： 合成生物学   农残检测   生物反应器   酶   生物技术  

摘要： 近年来,合成生物学在多个领域崭露头角,在农残检测中也发挥着越来越重要的作用。基于合成生物学模块化和工程化指导思想,各种基因部件的多样化组合为农残检测提供更多方案。简便、耐用、低成本、原位检测等特点也使其较传统检测手段具有更强的竞争力。但与此同时,合成生物学在农残检测中的应用也受到复杂检测环境和生物安全性等问题的影响。结合目前合成生物学在有机氯、有机磷、拟除虫菊酯和氨基甲酸酯类农药检测中的应用与创新实例,归纳合成生物学在农残检测中应用的原理,分析并探讨合成生物学技术未来在农残检测中的发展潜力与应用前景。