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关键词： Distillery wastewater treatment   High-rate anaerobic bioreactors   Anaerobic granular sludge   Next-generation sequencing   Whiskey spent wash   Granule size distribution  

摘要： Two full-scale high-rate bioreactors, i.e. external circulation sludge bed (ECSB) and expanded granular sludge bed (EGSB), were monitored for three years. Their performances for treating wastewater in a whiskey distillery were compared in terms of COD, pH, alkalinity and VFA. Even though feed flowrate highly fluctuated, COD removals of ECSB and EGSB were both excellent (95.7 +/- 1.3% and 94.8 +/- 3.0%, respectively). The influent and effluent characteristics of ECSB reactor were profiled and urea and urethane were also detected. High-strength properties of raw spent wash were exhibited in TOC, soluble COD and BOD5,20 degrees C of 13500, 37750, and 1950 mg.L-1, respectively and characterized by GC-MS. Anaerobic granular sludge sampled from different heights of ECSB reactor were fractionated for demonstrating vertical size distributions. Moreover, major species found by next-generation sequencing technique were archaea, i.e. Methanosaeta and Methanolinea, while major bacteria were Bacteroidetes with minor Nitrospiraceae. This metagenomic analysis provided an insight of anaerobic microbial consortium.

摘要： The aim of the present study was to develop an ion-selective electrode method for the continuous determination of the intracellular pH in Lactobacillus plantarum using a small-scale bioreactor. This method employed a salicylate-selective electrode basing on the distribution of salicylic acid across the cytoplasmic membrane. This developed electrode responded to salicylate concentrations above 20 mu mol/L with a Nernstian sensitivity. The energized and concentrated cells were added into a thermostated small-scale bioreactor that contained the salicylate anions dissolved in a 100 mmol/L potassium phosphate buffer at different pH values. The changes in salicylate concentration that occurred in the medium containing bacterial suspension were measured as a voltage change. The cells of Lactobacillus plantarum showed maintenance of pH homeostasis at the studied pH ranging from 4.0 to 7.0, and they kept a neutral intracellular pH up to 5.8. The simplicity of the measuring preparation and the relatively low cellular concentration, as well as the advantages of the small-scale bioreactor, lead us to believe that the described method can facilitate the study of the physicochemical factors on the intracellular pH of lactic acid bacteria using a single pH probe in one method.

关键词： Anaerobic granular sludge   Extracellular polymer substances   Calcium ions   COD degradation Rate  

摘要： In this study, batch tests were conducted with and without the addition of calcium ions to clarify the interaction between calcium ions and extracellular polymeric substances (EPS). The maximum degradation rates of EPS and chemical oxygen demand (COD) in the reactor with the addition of Ca2+ reached 58.26, 67.19, 69.35 mg.g(-1) mixed liquor suspended solids (MLSS) and 89.70%, 94.04%, 91.70%, respectively, and were higher than those in the control reactor. The results showed that Ca2+ (1000-2000 mg .L-1) significantly promoted the secretion of EPS and improved sludge digestion performance during the process of anaerobic digestion. In addition, Ca2+ changed the functional groups of EPS and the microstructure of granular sludge compared with the control reactor. The concentrations of EPS in the reactor with added Ca2+ were positively correlated with the COD degradation rate, with coefficients of determination of 0.88, 0.91, and 0.98 in reactors R-1, R-2, and R-3, respectively, which suggests that EPS can affect the bioactivity of anaerobic granular sludge (AnGS), and particularly the degradation of organics. The results were reaffirmed by analyzing volatile fatty acids (VFAs) and cytochrome c (c-Cyts). There was no obvious relationship between the EPS content and COD degradation rate in the control reactor (R-2 = 0.63), which indicates that Ca2+ may be an important factor in attaining the above results. Therefore, we speculate that Ca2+ caused changes in EPS, as the concentration of EPS increased and the COD degradation rate increased (and vice versa), which affected the digestion performance of AnGS.

关键词： HAMBR   Membrane fouling   Hydraulic retention time  

摘要： Membrane bioreactor (MBR) offers significant advantages for effluent quality, footprint, sludge production, and operation. In this study, the performance of an MBR was evaluated in a hybrid airlift membrane bioreactor (HAMBR) operating under various hydraulic retention times (HRTs). Results demonstrated that HAMBR could effectively remove organic and nutrient pollutants. The removal percentages of chemical oxygen demand, ammonium and total nitrogen for permeate and supernatant were in the range of 87%-99%, 44%-96%, and 45%-95%, respectively. The results indicated that the HAMBR can be used effectively for simultaneous nitrification-denitrification in the treatment of wastewater, even at low HRTs. Regarding membrane fouling rate, HRT of 36 h could significantly mitigate membrane fouling compared with the shorter HRTs and it was an optimal HRT value for removal of organic matter. Therefore, HAMBR was introduced as a superior MBR regarding performance efficiency and membrane fouling in the treatment of wastewater.

关键词： Airlift reactor   Draft tube   Volumetric oxygen transfer coefficient   Gas holdup   Mixing time   Pichia pastoris  

摘要： This study investigated the influence of the geometry of the draft tube on the mass transfer and energy efficiency in the airlift reactor with helical sieve plate (ALR-HSP). The power consumption efficiency was 46%-53% higher than the control condition by optimizing the draft tube. A set of empirical equations was used to describe the gas holdup and volumetric mass transfer coefficients corresponding to the geometry of draft tubes in the ALR-HSP for the water-air system. The comparative cultivation of Pichia pastoris was carried out using the ALR-HSP and the conventional airlift reactor (CALR). The biomass increased by 20%, the maximal specific growth rate during the logarithmic growth phase nearly doubled, and volumetric oxygen transfer coefficient increased by 21%-47% under the same culture conditions. Results preliminarily demonstrated the superior performance and practicability of the ALR-HSP in enhancing oxygen transfer efficiency and aerobic biological reaction efficiency. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

关键词： magnetic bioreactor   magnetoactive scaffolds   tissue engineering   magnetic actuator   magnetoelectric stimulation  

摘要： Biomimetic bioreactor systems are increasingly being developed for tissue engineering applications, due to their ability to recreate the native cell/tissue microenvironment. Regarding bone-related diseases and considering the piezoelectric nature of bone, piezoelectric scaffolds electromechanically stimulated by a bioreactor, providing the stimuli to the cells, allows a biomimetic approach and thus, mimicking the required microenvironment for effective growth and differentiation of bone cells. In this work, a bioreactor has been designed and built allowing to magnetically stimulate magnetoelectric scaffolds and therefore provide mechanical and electrical stimuli to the cells through magnetomechanical or magnetoelectrical effects, depending on the piezoelectric nature of the scaffold. While mechanical bioreactors need direct application of the stimuli on the scaffolds, the herein proposed magnetic bioreactors allow for a remote stimulation without direct contact with the material. Thus, the stimuli application (23 mT at a frequency of 0.3 Hz) to cells seeded on the magnetoelectric, leads to an increase in cell viability of almost 30% with respect to cell culture under static conditions. This could be valuable to mimic what occurs in the human body and for application in immobilized patients. Thus, special emphasis has been placed on the control, design and modeling parameters governing the bioreactor as well as its functional mechanism.

摘要： Microbial community dynamics and PTA wastewater degradation performance of sequentially connected two-stage upflow anaerobic sludge blanket (UASB) bioreactors have been studied for 225 days. The working volume of acidogenic (R1) and methanogenic reactors (R2) have sixfold differences. Thus, the reactors operated under different hydraulic retention time (HRT) conditions, which are preferential for PTA wastewater content. Archeal and bacterial profiles of granules were analyzed with denaturing gradient gel electrophoresis (DGGE) and real-time quantitative PCR (Q-PCR) techniques. According to high-pressure liquid chromatography (HPLC) results, 4-Carboxybenzaldehyde (4-CBA) and acetic acid (AA) completely degraded in the first stage, whereas terephthalate (TA) and p-toluic acid (p-TA) degradation ratios were 90% and 47% in the second stage, respectively. The methane content of the UASB reactor was determined as 76% by gas chromatography (GC) analysis. Microbial community analysis indicated that the members of hydrogenotrophic methanogen groups Methanobacteriales and Methanomicrobiales were dominantly responsible for methane production throughout the process.

关键词： Membrane bioreactor   Membrane fouling   Soluble microbial products   Molecular weight distribution   Wastewater treatment  

摘要： While molecular weight distribution (MWD) is one of the most important properties of soluble microbial products (SMPs), mechanisms underlying effects of MWD of SMPs on membrane fouling have not well unveiled. In this study, it was found that, the supernatant of sludge suspension in a membrane bioreactor (MBR) for wastewater treatment can be fractionated into a series of SMPs samples with different molecular weight (MW) fraction. The real gel sample mainly formed by the rejected SMPs on membrane surface had a high specific filtration resistance (SFR) of 1.21 x 10(16) m(-1) kg(-1). The SFR of SMPs samples and the model foulants of polyethylene glycol (PEG) increased with their MW. The change trend of SFR with MW cannot be sufficiently explained by three-dimensional excitation-emission matrix (EMM) and chemical compositions. Tyndall effect analysis indicated that gelating ability of SMPs and PEG in the solution increased with their MW. Scanning electron microscope (SEM) confirmed gel structure changes with the PEG MW. Accordingly, mechanisms based on Carman-Kozeny equation and Flory-Huggins lattice theory were proposed to interpret SFR of SMPs with low and high MW, respectively. Simulating these two mechanistic models on PEG samples resulted in the comparable SFR data to the experimental ones, indicating the correctness and feasibility of the proposed mechanisms. The proposed mechanisms provided in-depth understanding of membrane fouling regarding MW, facilitating to develop effective membrane fouling mitigation strategies. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： bioreactor scale-up   bioreactor sparger   CHO cell culture   high gas entrance velocity   scale down model  

摘要： There are three main potential sources for cell shear damage existing in stirred tank bioreactors. One is the potential high energy dissipation in the immediate impeller zones;another from small gas bubble burst;and third is from high gas entrance velocity (GEV) emitting from the sparger. While the first two have been thoroughly addressed for the scale-up of Chinese hamster ovary (CHO) cell culture knowing that a wide tolerable agitation range with non-damaging energy dissipation exists and the use of shear protectants like Pluronic F68 guard against cell damage caused by bubble burst, GEV remains a potential scale-up problem across scales for the drilled hole or open pipe sparger designs. GEV as high as 170 m/s due to high gas flow rates and relatively small sparger hole diameters was observed to be significantly detrimental to cell culture performance in a 12,000 L bioreactor when compared to a satellite 2 L bioreactor run with GEV of <1 m/s. Small scale study of GEV as high as 265 m/s confirmed this. Based on the results of this study, a critical GEV of >60 m/s for CHO cells is proposed, whereas previously 30 m/s has been reported for NS0 cells by Zhu, Cuenca, Zhou, and Varma (2008. Biotechnol. Bioeng., 101, 751-760). Implementation of new large scale spargers with larger diameter and more holes lowered GEV and helped improve the cell culture performance, closing the scale-up gap. Design of such new spargers was even more critical when hole plugging was discovered during large scale cultivation hence exacerbating the GEV impact. Furthermore, development of a scale down model based on mimicry of the large scale GEV profile as a function of time was proven to be beneficial for reproducing large scale results.

关键词： Tissue culture   Proliferation   Mass propagation   In vitro-immersion  

摘要： The objective of this study was to set up a plant micropropagation facility to mass propagate sugarcane, energy cane, and related clonally propagated species. An efficient methodology for micropropagation of energy cane and perennial grasses using temporary immersion bioreactors was developed. Several different methods of tissue culture initiation, multiplication, and rooting were evaluated for several varieties of sugarcane (Saccharum officinarumL.) and sugarcane-related species such asErianthusspp.,Miscanthusspp., andSorghumspp. x sugarcane hybrids, all from a germplasm collection. Apical meristem cultures were initiated for all genotypes that were micropropagated, when liquid or semisolid Murashige and Skoog (MS) medium was used, which was supplemented with 0.1-0.2 mg L(-1)BAP, 0.1 mg L(-1)kinetin, 0-0.1 mg L(-1)NAA, and 0-0.2 mu g L(-1)giberellic acid. These cultures produced shoots between 4 and 8 wk after initiation. Shoot regeneration from leaf rolls or immature inflorescences was observed as early as 4 wk after initiation. Shoot multiplication was successful for all genotypes cultured in MS medium with 0.2 mg L(-1)BAP and 0.1 mg L(-1)kinetin. Energy cane had a significantly higher combined multiplication rate when grown under four or five LED lamps than when grown under three LED lamps, or under fluorescent lights in a growth chamber. The addition of 2 mg L(-1)NAA produced faster and better rooting in all of the genotypes tested. Shoots produced well-developed roots after one cycle of 15-21 d in the bioreactors. The maximum number of plantlets produced per bioreactor was 1080. Plantlets developed a vigorous root system and were ready to be transplanted into the field after 2 mo. A protocol was standardized for different energy cane clones that were recommended for their biomass production and cell wall composition. Different tissues were used to speed up or facilitate tissue culture initiation. Visual assessment of micropropagated plants in the field did not