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关键词： bioremediation   diatom biofilms   fixed‐   bed bioreactor   wastewater  

摘要： This present study aims to demonstrate the efficiency of a simple biological wastewater treatment process using diatoms for removing mainly nitrogen and phosphorus from four types of effluents: synthetic wastewater (SW), a real urban effluent (RUE), industrial effluent (IE), and agricultural sewage (AS). The process consists of promoting the attachment of diatoms to several grain sizes to form biofilms, to define the best grain size for the performance and to study the evolution of diatom biofilms and some parameters, such as ammonium, nitrate, phosphorus, and chemical oxygen demand (COD). Diatoms used in this study are collected from the highest rate of biomass growth of diatoms grown in an experimental photobioreactor. Initially, four fixed-bed bioreactors in batch mode are experienced over artificial conditions and filled with coarse sand (B1), small gravel (B2), medium gravel (B3), and coarse gravel (B4). The bioreactor B2 is selected to study the evolution of nutrients for the four types of wastewater. The best removal rates are measured as 75.26% for ammonium, 72.43% for nitrate, and 61.65% for phosphorus for SW. Important rates of COD are also recorded for RUE (75.29%). These results demonstrate that nutrients in the wastewater can be successfully removed by diatom biofilms.

关键词： Biogas upgrading   Biogas-lift bioreactor   Waste-frying oil   Anaerobic digestion  

摘要： Biogas upgrading from anaerobic digestion of waste frying oils (WFO) was accessed in this study. For that, two bioreactors (Rb-biogas-lift bioreactor with gas and liquid recirculation, Rc-control reactor with liquid recirculation) were fed three times per week, with a mixture of WFO, glycerol and volatile fatty acids (VFA). Rb produced 1.4 times more biogas with higher methane content (79%) than Rc (67%). Higher relative abundance of hydrogenotrophic methanogens (34%-39%) was observed in Rb, when compared to Rc (16%-21%). The relative abundance of Sprochaetia class, which includes some homoacetogens/ syntrophic acetate oxidizing genera, was also higher in Rb. This work shows that biogas recirculation applied in the biogas-lift bioreactor facilitated WFO degradation, most probably due to the selective enrichment of hydrogenotrophic methanogens. Recirculation of CO2 present in the biogas and reverse homoacetogenesis (i.e. syntrophic acetate oxidation) seem to be the main factors involved in the stimulation of hydrogenotrophic methanogenesis. (c) 2020 Elsevier Ltd. All rights reserved.

关键词： auto‐   perfusion   cell retention   high cell concentration   microfluidic   miniature  

摘要： Medium perfusion is critical in maintaining high cell concentration in cultures. The conventional membrane filtration method for medium exchange has been challenged by the fouling and clogging of the membrane filters in long-term cultures. In this study, we present a miniature auto-perfusion system that can be operated inside a common-size laboratory incubator. The system is equipped with a spiral microfluidic chip for cell retention to replace conventional membrane filters, which fundamentally overcomes the clogging and fouling problem. We showed that the system supported continuous perfusion culture of Chinese hamster ovary (CHO) cells in suspension up to 14 days without cell retention chip replacement. Compared to daily manual medium change, 25% higher CHO cell concentration can be maintained at an average auto-perfusion rate of 196 ml/day in spinner flask at 70 ml working volume (2.8 VVD). The auto-perfusion system also resulted in better cell quality at high concentrations, in terms of higher viability, more uniform and regular morphology, and fewer aggregates. We also demonstrated the potential application of the system for culturing mesenchymal stem cells on microcarriers. This miniature auto-perfusion system provides an excellent solution to maintain cell-favorable conditions and high cell concentration in small-scale cultures for research and clinical uses.

关键词： bone   mechanical loading   metastasis   multiphysics   tissue engineering  

摘要： Incurable breast cancer bone metastasis causes widespread bone loss, resulting in fragility, pain, increased fracture risk, and ultimately increased patient mortality. Increased mechanical signals in the skeleton are anabolic and protect against bone loss, and they may also do so during osteolytic bone metastasis. Skeletal mechanical signals include interdependent tissue deformations and interstitial fluid flow, but how metastatic tumor cells respond to each of these individual signals remains underinvestigated, a barrier to translation to the clinic. To delineate their respective roles, we report computed estimates of the internal mechanical field of a bone mimetic scaffold undergoing combinations of high and low compression and perfusion using multiphysics simulations. Simulations were conducted in advance of multimodal loading bioreactor experiments with bone metastatic breast cancer cells to ensure that mechanical stimuli occurring internally were physiological and anabolic. Our results show that mechanical stimuli throughout the scaffold were within the anabolic range of bone cells in all loading configurations, were homogenously distributed throughout, and that combined high magnitude compression and perfusion synergized to produce the largest wall shear stresses within the scaffold. These simulations, when combined with experiments, will shed light on how increased mechanical loading in the skeleton may confer anti-tumorigenic effects during metastasis.

关键词： Ethanol fermentation processes   Bioreactor temperature control   Nonlinear systems   Adaptive control   Observers  

摘要： This study addresses the design of advanced control schemes implemented for a continuous fermentation process used to produce ethanol. Due to the inaccuracy of the models that express this complex process, a feasible controller is required to maximize the production of ethanol and to minimize its environmental impact, despite the existence of some significant uncertainties. Therefore, novel estimation and control schemes are designed and tested. These schemes are adaptive control laws including nonlinear estimation algorithms: a sliding mode observer to estimate the unknown influent concentration, but also state observers and parameter estimators used to estimate the unknown states and kinetics. Since the temperature is an important factor for an efficient operation of the process, an algorithm for temperature control in the bioreactor is also developed. To verify the control algorithms effectiveness, several tests performed via numerical simulations under realistic conditions are presented.

关键词： Bioreactor   Shear stress   Bioprocess   CFD   Chlamydomonas  

摘要： The aim of this study is to investigate the potential of a novel design considering low shear horizontal bioreactor (LSB-R) with counter rotation U-shape impellers. Bioreactors (LSB-R and STR) were compared under the same mixing time (23 +/- 2 s) using Computational Fluid Dynamics analysis focusing on the shear stresses. The highest shear stress was around the impeller tips with an average shear stress found to reach up to 0.8 Pa for LSB-R a very small value compared to the 100-fold increase inside the STR. Cell wall deficient and motility impaired mutants of Chlamydomonas were used in the experiments to see the effects of shear stress on growth and morphology. Biomass productivities were almost doubled, and specific growth rates were increased by LSB-R. On the other hand, the motility impaired cells aligned as colonies to protect from shear forces in STR and a rapid death occurred in cells with flagella due to continuous deflagellation and cell damage. The results indicate that;LSB-R design has great advantage on lowering shear stress, eliminating excessive hydrodynamic forces, providing mild operation conditions.

关键词： alcoholic fermentation   bioreactor advanced control   metabolic flux control   micro‐   aeration   Saccharomyces cerevisiae  

摘要： Various bio-based processes depend on controlled micro-aerobic conditions to achieve a satisfactory product yield. However, the limiting oxygen concentration varies according to the micro-organism employed, while for industrial applications, there is no cost-effective way of measuring it at low levels. This study proposes a machine learning procedure within a metabolic flux-based control strategy (SUPERSYS_MCU) to address this issue. The control strategy used simulations of a genome-scale metabolic model to generate a surrogate model in the form of an artificial neural network, to be used in a micro-aerobic fermentation strategy (MF-ANN). The meta-model provided setpoints to the controller, allowing adjustment of the inlet air flow to control the oxygen uptake rate. The strategy was evaluated in micro-aerobic batch cultures employing industrial Saccharomyces cerevisiae yeast, with defined medium and glucose as the carbon source, as a case study. The performance of the proposed control scheme was compared with a conventional fermentation and with three previously reported micro-aeration strategies, including respiratory quotient-based control and constant air flow rate. Due to maintenance of the oxidative balance at the anaerobiosis threshold, the MF-ANN provided volumetric ethanol productivity of 4.16 g center dot L-1 center dot h(-1) and a yield of 0.48 g(ethanol).g(substrate)(-1), which were higher than the values achieved for the other conditions studied (maximum of 3.4 g center dot L-1 center dot h(-1) and 0.35-0.40 g(ethanol)center dot g(substrate)(-1), respectively). Due to its modular character, the MF-ANN strategy could be adapted to other micro-aerated bioprocesses.

关键词： Lentzea sp. OUR-I1   Air-lift bioreactor   Acid-treated SSP   Chitosanase   Chitin   Pigment  

摘要： Chitosanase is an attractive enzymatic tool for the production of bioactive chitooligosaccharides. Nevertheless, its industrial use is restricted by its high cost and insufficient availability because chitosanase production needs an expensive inducer, chitosan. Therefore, this study developed a process to produce chitosanase from abundant and inexpensive shrimp shell waste entailing the pretreatment of shrimp shell powder (SSP) with 0.4 M acetic acid (AcSSP), which increased the substrate bioavailability and enhanced the chitosanase production by Lentzeasp. OUR-I1 four-fold. The initial flask-based process was scaled up into an air-lift bioreactor (ALB) and the maximum chitosanase activity (0.974 U/mL) was observed at an aeration rate of 2.0 vvm. This is the first report indicating the suitability of ALB for chitosanase production byLentzeasp. OUR-I1. Interestingly, Lentzeasp. OUR-I1 also produces a yellow pigment with prospective structure as carotenoids, indicating that the mycelium could be reused in the production of pigments. In addition, the fermented AcSPP displayed the FTIR spectrum of chitin and has high potential as an absorbent for methyl orange, methylene blue and coomassie brilliant blue, with a maximum decolorization efficiency of 73.21, 64.59 and 87.93%, respectively. The process developed represents a cost effective and environmentally friendly method of valorizing a waste product from the food industry into valuable bioproducts. [GRAPHICS] .

关键词： Anammox bacteria   Autotrophic nitrogen removal   Microbial ecology   ANITA (TM) Mox technology   Full scale reactor   Reject water treatment  

摘要： The aim of this work was to study the operational performance and the microbial community dynamics during the start-up of ANITA (TM) Mox technology implemented at full-scale wastewater treatment plant in Finland to treat reject water from anaerobic digesters. The average ammonium removal in the studied setup reached around 90%, withstanding ammonium loads up to 0.13 g N m(-2)h(-1). The nitrite concentration in the effluent did not exceed 10 mg L-1, and there was a slight accumulation of NO3--N during the operation which was controlled. Thus, the result showed a robust success to high ammonium loading in presence of organic matter. The sequencing showed a heterogeneous microbial population where Methanosaeta, WCHA1-57 genus, Sphingobacteriia, Chlorobia and diverse unknown fungi were found as dominant phylotypes. Moreover, members of the Brocadiaceae family were dominant in the adhered biomass, mostly represented by Candidatus Scalindua, rarely reported in WWTPs. Overall, the results demonstrated a drastic effect of region-specific operational conditions on carrier biofilm microbial communities as it was demonstrated by the microbial studies. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： Aquatic life   Effluent   Recirculating aquaculture systems   Salmonid  

摘要： The denitrifying woodchip bioreactor is designed to remediate nitrate-rich water, including those produced from aquaculture effluents. Reuse of treated bioreactor outflows in recirculating aquaculture would offer considerable water savings and valuable alkalinity recuperation. However, such bioreactors may leach detrimental woodbound contaminants, preventing outflow reuse. To determine water reuse potential, woodchip media from two hardwood species (white ash, Fraxinus americana;Norway maple, Acer platanoides) were evaluated for 206 d under a range of operating conditions (start-up, steady-state, reducing conditions, and drying-rewetting cycles) for a spectrum of potentially harmful dissolved contaminants. Aerated outflows also were evaluated for acute and chronic toxicity to the biologically sensitive invertebrate Ceriodaphnia dubia. Dissolved metal leaching subsided within the first few weeks of operation, though initial concentrations of copper and zinc were detected at concentrations of concern. Elevated concentrations of tannins-lignin and total ammonia nitrogen were detected throughout the study and were influenced by operational phase. Acute toxicity was not generally detected, though chronic toxicity was observed during drying-rewetting cycles in the maple outflows. The measured toxicity was not correlated with water chemistry, indicating an additive effect of several toxicants. Overall, significant differences in outflow water quality between ash and maple wood species were negligible. Results indicated that bioreactor outflows may be applicable for aquacultural reuse, though reusing outflows immediately following start-up or restarting after a dry period would not be recommended.