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关键词： Membrane bioreactor   In-situ membrane cleaning   Extracellular polymeric substances   Interactions energy   Membrane fouling potential  

摘要： In-situ chemical cleaning with sodium hypochlorite (NaClO) is often employed for maintaining constant permeability in a membrane bioreactor (MBR). In this study, the effect of NaClO shock on the rapid formation of initial membrane fouling was investigated over the course of the in-situ cleaning of a MBR. Variations of trans membrane pressure (TMP) in the different runs indicated that the bulk sludge after NaClO-shock promotes the rapid formation of initial membrane fouling. After in-situ cleaning, the sludge had a high protein content in different extracellular polymeric substance layers and a substantial deterioration in sludge filterability compared to raw sludge. Based on the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, NaClO shock significantly changes the surface properties of raw sludge. It reduces the surface electron donor component (gamma(-)) and increases surface hydrophobicity. The sludge after NaClO-shock exhibited a stronger adhesive energy with the membrane and higher self-cohesive ability, resulting in severe membrane fouling.

关键词： Cake layer   Chromate exposure   Membrane bioreactor   Structural characteristics  

摘要： Chromate (CrO42-) exposure, especially high concentration (mg/L), still probably occurs in the industrial and mining area due to industrial accidents or even illegal discharge, though CrO42- has been restricted to be discharged into wastewater treatment system (WWTS). Therefore, this study was applied to better understand the structural characteristics of cake layer in membrane bioreactor (MBR), which is one of best alternative for WWTS of industrial or mining area, with Cro42-exposure. Three submerged MBRs with CrO42- exposure (10 mg/L was normal high concentration CrO42-;50 mg/L as extreme level for better identification;0 mg/L as control condition) were applied in this study. Results showed that CrO42- exposure caused an obvious variation of cake layer structure. Because of organic component variation, cake layer structure with CrO42- exposure was re-constructed into loose and porous with biomicromolecules, and resulted in the rapid cake layer thickness increase, finally leading to severe membrane biofouling. Additionally, CrO42- distributed evenly along the cross-sectional cake layer. CrO42- only induced the inorganic structure variations of cake layer, but without any obvious effects on the other inorganic elements structure. CrO42- exposure induced the bacterial community structure variation and led to tolerated-CrO42- microorganisms as the majority in cake layer community, but had no obvious effects on the population diversity.

关键词： Mine water treatment   Passive biological treatment   Zinc   Cadmium  

摘要： Acid mine drainage (AMD) is a major environmental challenge for the mining industry in northern climates. Laboratory-scale experiments were conducted to test various simple and complex carbon sources available in the Yukon as electron donors for sulfate reduction to allow the subsequent removal of Cd and Zn from a Yukon AMD. The 1L capacity bioreactors were monitored biweekly at 5 degrees C. After 162 days, a diminution of both total organic carbon and sulfate concentrations was observed in all bioreactors. A long adaptation period was necessary before consumption of the carbon source started, which might be due to the cold temperature. Simple organic sources of carbon (methanol and ethylene glycol) and complex organic sources of carbon (potato oil, brewery residue, peat, and straw) were used to support SRB growth. Methanol and ethylene glycol led to a diminution of sulfate concentrations of 71.2 and 36.9%, respectively, while the decrease of sulfate concentrations was limited to 13.8 and 5.3% when using peat and straw, respectively.

关键词： Bioreactors   Manufacturing   Cell culture   Construction contracts  

摘要： AGC Biologics is a recent integration of Asahi Glass Company (AGC) Bioscience, a glass and chemical producer under AGC, Biomeva GmbH, a contract manufacturing organization, and CMC Biologics, a contract biologics manufacturer. The company noted that it is the only supplier that today can provide single-use bioreactors with capacities greater than 2000 L. Benefits of the 4000-L single-use bioreactor include a reduction in capital, facility, and disposables cost by doubling cell-culture capacity in approximately the same floor space. Other features of the line include large production volumes, seamless process transfer and scale-up, rapid container loading, and a non-proprietary supply chain.

关键词： continuous mammalian cell cultivation   small-scale bioreactor   DoE   mAb   process optimization  

摘要： Continuous processes such as perfusion processes can offer advantages compared to fed-batch or batch processes in bio-processing: improved product quality (e.g. for labile products), increased product yield, and cost savings. In this work, a semi-perfusion process was established in shake flasks and transferred to an automated small-scale bioreactor by daily media exchange via centrifugation based on an existing fed-batch process platform. At first the development of a suitable medium and feed composition, the glucose concentration required by the cells and the cell-specific perfusion rate were investigated in shake flasks as the conventional scale-down system. This lead to an optimized process with a threefold higher titer of 10 g/L monoclonal antibody compared to the standard fed-batch. To proof the suitability and benefit as a small-scale model, the established semi-perfusion process was transferred to an automated small-scale bioreactor with improved pH and dissolved oxygen control. The average specific productivity improved from 24.16pg/(c*d) in the fed-batch process and 36.04pg/c*d in the semi-perfusion shake flask to 38.88pg/(c*d) in the semi-perfusion process performed in the controlled small-scale bioreactor, thus illustrating the benefits resulting from the applied semi-perfusion approach, especially in combination with controlled DO and pH settings. (c) 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2757, 2019.

关键词： Mesenchymal stromal cell   Hollow-fiber bioreactor   Regenerative medicine   Cell therapy   Extracellular matrix   Automated cell culture  

摘要： The addition of a coating reagent to promote cell adherence is necessary to prepare the membrane surface of the Quantum (R) Cell Expansion System hollow-fiber bioreactor for the culture of mesenchymal stem cells. In this study, the efficacy of 8 potential coating reagents has been compared in terms of the doubling times of their cell populations, cell morphology, characterization via flow cytometry, and capacity for trilineage differentiation. Human fibronectin (FN), pooled human cryoprecipitate (CPPT), and recombinant human vitronectin (VN) were successful as coating reagents, and each product has advantages in different cell culture contexts. Mesenchymal stem cells harvested from Quantum cultured with each of these 3 compounds as coating reagents all met International Society for Cellular Therapy standards for plastic adherence, surface marker expression, and successful trilineage differentiation. No significant differences were observed among the doubling times from Quantum harvests using FN, CPPT, or VN as coating reagents (P = 0.31). Coating with gelatin, human serum albumin, collagen I, poly-L-lysine, and poly-D-lysine resulted in significantly lower harvest yield;these agents are not recommended for use as coating reagents in the Quantum system.

关键词： Tissue engineered heart valve   Biomechanical stimulation   Biochemical stimulation   Three-dimensional tissue culture   ISO 5840  

摘要： PurposeTissue engineered heart valves (TEHV) are being investigated to address the limitations of currently available valve prostheses. In order to advance a wide variety of TEHV approaches, the goal of this study was to develop a cardiac valve bioreactor system capable of conditioning living valves with a range of hydrodynamic conditions as well as capable of assessing hydrodynamic performance to ISO 5840 *** bioreactor system was designed based on the Windkessel approach. Novel features including a purpose-built valve chamber and pressure feedback control were incorporated to maintain asepsis while achieving a range of hydrodynamic conditions. The system was validated by testing hydrodynamic conditions with a bioprosthesis and by operating with cell culture medium for 4weeks and living cells for *** bioreactor system was able to produce a range of pressure and flow conditions from static to resting adult left ventricular outflow tract to pathological including hypertension. The system operated aseptically for 4weeks and cell viability was maintained for 2weeks. The system was also able to record the pressure and flow data needed to calculate effective orifice area and regurgitant *** have developed a single bioreactor system that allows for step-wise conditioning protocols to be developed for each unique TEHV design as well as allows for hydrodynamic performance assessment.

关键词： Membrane bioreactors   Start-up   Salt stress   Microbial community   Soluble microbial products (SMP)  

摘要： Start-up of membrane bioreactor under different NaCl stress was investigated in this study. Results showed that nearly 90% chemical oxygen demands and ammonia nitrogen (NH4+-N) was oxidized in none and 0.5% NaCl condition during the start-up stage. While 1% NaCl dramatically depressed the utilization of NH4+-N and about 4weeks were required for adaption of sludge biomass to saline condition. In addition, the accumulation of nitrite high to 11.84mg/L was observed in 1% NaCl stress, indicating the more inhibition on the activity of nitrite oxidizing bacteria. Microbial community responded to the different salinity levels. The phylum Proteobacteria and Bacteroidetes occupied over 60% in all the three MBRs. Salinity enriched the relative abundance of Maribacter, Methyloversatilis, Aeromonas and Curvibacter, while reducing the proportion of Nitrospira and Haliscomenobacter. Nitrospirae decreased sharply at 1% NaCl accounting for the accumulation of nitrite. Higher content of soluble microbial products (SMP) under saliferous MBR were released, which deteriorated the permeability of membrane module. Protein-like substances and humic substances were the main ingredients of SMP, of which the former contributed more to membrane flux decline. This study provided better understanding on the impact of salinity on the start-up of MBR.

关键词： Sulphate reduction   Sulphidogenesis   Wastewater treatment   Sequencing batch reactor   Transient feeding conditions   Feast-famine  

摘要： This work aimed to study the effect of transient feeding conditions on sulphidogenesis in 8 sequencing batch bioreactors (SBR). SBR L1 and H1, operated under steady-state conditions were used as the control reactors, while four SBR were tested under transient feeding conditions using moderate (L2 and L3, feast and famine: 2.5 and 0 g SO42-center dot L-1) and high (H2 and H3, feast and famine: 15 and 0 g SO42-center dot L-1) loads. The sulphate removal efficiency (RE) was >= 90% in SBR L2, L3 and H1. The NH4+ famine conditions resulted in a higher sulphate RE (>= 40% H3) compared to feast conditions (<= 20% H2). Besides, the sulphidogenic first-order kinetic constant was 4% larger and the use of electron donor was 16.6% more efficient under NH4+ famine conditions. Sulphidogenesis is robust to transient feeding conditions, but not when applying high loading rates (SBR H2 and H3).

关键词： hydraulic fracturing   extractive membrane bioreactors   organic acids   ionizable compounds   transport through polymers  

摘要： BACKGROUND The water-intensive practice of hydraulic fracturing produces wastewater containing a variable matrix of organic and inorganic compounds, including ions and ionizable organic compounds. Extractive membrane bioreactors (EMBs) operating with tailored polymer membranes can selectively sequester and/or transport these solutes for biological treatment. Four grades of Hytrel (TM) tubing were compared for their suitability in EMB systems, based on the polymers' thermodynamic affinity for solutes and their ability to transport or speciate ionic wastewater constituents. RESULTS Of the four Hytrel (TM) grades compared, high water content types (30% and 54% equilibrated water content) facilitated the transport of ionic species through the tubing, with all monovalent species being transported through both high-water content grades, and lack of transport through the low-water content tubing (3% and 5%). Undissociated organic acids were transported through all tubing types and dissociated acids were able to permeate only high-water content grades. Using this differential ability to transport/not transport an organic acid depending on its dissociation state, a low-water content Hytrel (TM) grade of tubing was able to concentrate a dilute butyric acid solution by 220% after 48 h. CONCLUSION The use of polymeric tubing for EMB applications for the treatment of hydraulic fracturing wastewater requires knowledge of both solute affinity and water content for complex waste streams, both of which affect the capability to transport organic and ionic species. (c) 2018 Society of Chemical Industry