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关键词： Effluents  

摘要： Water reuse is believed to be a sustainable solution to overcome the scarcity of freshwater. Aerobic and anaerobic membrane bioreactors are becoming an effective technology for wastewater treatment and reuse. Aerobic membrane bioreactors show good nutrient removal, whereas those that are anaerobic have nutrient-rich effluent, enabling the direct agricultural use of the effluent. As a result, the end use will dictate the potential environmental impacts of the bioreactor's application. Therefore, with the consideration of the end use (i.e., discharge or reuse) of the effluent, this study aimed to compare the environmental and economic impacts associated with full-scale aerobic and anaerobic membrane bioreactors for municipal wastewater treatment under different end use scenarios using life cycle assessment and cost analysis. The results of these analyses show that anaerobic bioreactors have greater environmental impacts and life cycle cost than aerobic bioreactors in the discharge scenario due to the incorporation of a biological nutrient removal system. In the reuse scenario, anaerobic membrane bioreactors have lower impacts that are attributable to the offset of the nutrients required for crops, and the potential benefits vary depending on the types of crops receiving the reclaimed water. Integrating anaerobic membrane bioreactors with agricultural fertigation resulted in effluent water nitrate concentrations (after crop uptake and soil treatment) of <2 mg L-1 in most U.S. states. This indicated that the use of the anaerobic membrane bioreactors effluent for fertigation could be a win-win solution to both irrigation water shortage and high environmental impact associated with nutrient removal.

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关键词： aerobic digestion   dynamic membrane   high strength food wastewater   woven filter cloth  

摘要： Dynamic membranes (DMs) defined as cake layer forms on a support material such as filter cloth have been of great interest in recent years. The usage of DMs can reduce the capital cost significantly and energy consumption during wastewater treatment by replacing the conventional membrane. The formation of an active dynamic cake layer is highly related to the retention of particles on the support material surface. In this study, different pore sizes of monofilament woven filter cloth made of polypropylene (PP;20, 40, and 60 mu m) were installed as a flat sheet in a DM bioreactor (DMBR) to treat high strength food wastewater [>1,000 mg/L chemical oxygen demand (COD)]. The wastewater treatment performances, namely COD, turbidity, total solid separation, and total ammonia nitrogen removal efficiencies, were assessed daily. The system achieved average COD removals higher than 80% and 70% for smaller pore size and larger pore size, respectively. Based on the results (duration of 4 days), the 20 mu m pore size monofilament filter cloth was found most suitable for the cake layer development. The results also demonstrate that the biofilm composed of the cake layer of the DM on smaller pore size significantly concurs with the high treatment efficiency compared with the larger pore size.

关键词： Membrane bioreactor (MBR)   Biofouling control   Quorum quenching   Microbial composition  

摘要： In conventional membrane bioreactor (MBR) treatment systems, Gram-negative bacterial population appears to be always outnumbered Gram-positive community. Thereby, acyl homoserine lactones (AHLs), major signaling molecules utilized by Gram-negative bacteria, have been targeted for biofouling control in quorum quenching (QQ) based studies. This study investigated the impact of AHL and autoinducer-2 (AI-2)-degrading QQ consortium on the selective accumulation of microbial communities in a QQ MBR (MBR-QQb). The results show that addition of the QQ consortium (in the form of beads) increased the filtration time of MBR-QQb by 3.5 times. The distribution of mixed liquor extracellular polymeric substances (EPS), especially the tightly bound (TB) proteinous EPS and the floc size were strongly affected by the QQ activity, and the endless 'battle' between QQ and quorum sensing (QS). More importantly, QQ induced the significant suppression of Gram-negative bacterial community. The average abundance of Gram-positive bacteria at the genus level in the biocake of MBR-QQb (51%) was significantly higher than that of the control MBR (11%) and the MBR with vacant beads (28%). These findings suggest that an unintended condition is created to favor the growth of Gram-positive bacteria in QQ MBRs, resulting in a distinct microbial social network in both bulk sludge and biocake. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： activated sludge   aggregate size   biodiversity   network analysis   niche differentiation  

摘要： The size of bacterial aggregates can determine both nutrient removal and sludge/water separation in activated sludge processes. In this study, the bacterial community structures and network associations of different sized aggregates obtained from a full-scale membrane bioreactor plant over a one-year period were investigated. Our results showed that biodiversity of larger sized aggregates was significantly higher than that of smaller ones and that the bacterial compositions of different sized aggregates differed significantly from each other. Bacteria related to nutrient removal (e.g. denitrification, hydrolysis and fermentation) were found to be significantly more abundant in larger aggregates than smaller ones. Network analysis revealed significant difference in species-species interactions, topological roles of individual OTU and keystone populations among different sized aggregates. Moreover, the occurrence of keystone OTUs affiliated with denitrifiers (Thermomonas) in networks of large and medium aggregates may suggest that denitrification influences bacterial interactions in large and medium aggregates. Overall, our results indicate the aggregates size-dependence of bacterial community separation in activated sludge. The current findings not only can provide guidance for process design and operation optimization, but also highlight the necessity for paying more attentions to the aggregate-based community, metabolic function and gene expression of activated sludge in future studies.

关键词： Bayesian   PLS-DA   reduced scale model   statistical qualification  

摘要： A novel method for the qualification of reduced scale models (RSMs) was illustrated using data from both a 250-ml advanced microscale bioreactor (ambr) and a 5-L bioreactor RSM for a 2,000-L manufacturing scale process using a CHO cell line to produce a recombinant monoclonal antibody. The example study showed how the method was used to identify process performance attributes and product quality attributes that capture important aspects of the RSM qualification process. The method uses two novel statistical approaches: multivariate dimension reduction and data visualization techniques, via partial least squares discriminant analysis (PLS-DA), and Bayesian multivariate linear modeling for inferential analysis. Bayesian multivariate linear modeling allows for individual probability distributions of the differences of the mean of each attribute for each scale, as well as joint probability statements on the differences of the means for multiple attributes. Depending on the results of this inferential procedure, PLS-DA is used to identify the process performance outputs at the different scales which have the greatest negative impact on the multivariate Bayesian joint probabilities. Experience with that particular process can then be leveraged to adjust operating conditions to minimize these differences, and then equivalence can be reassessed using the multivariate linear model.

关键词： bioprocess   cryopreservation   embryonic stem cells   scale-up   stirred suspension bioreactors  

摘要： Embryonic stem cells (ESCs) have almost unlimited proliferation capacity in vitro and can retain the ability to contribute to all cell lineages, making them an ideal platform material for cell-based therapies. ESCs are traditionally cultured in static flasks on a feeder layer of murine embryonic fibroblast cells. Although sufficient to generate cells for research purposes, this approach is impractical to achieve large quantities for clinical applications. In this study, we have developed protocols that address a variety of challenges that currently bottleneck clinical translation of ESCs expanded in stirred suspension bioreactors. We demonstrated that mouse ESCs (mESCs) cryopreserved in the absence of feeder cells could be thawed directly into stirred suspension bioreactors at extremely low inoculation densities (100 cells/ml). These cells sustained proliferative capacity through multiple passages and various reactor sizes and geometries, producing clinically relevant numbers (10(9) cells) and maintaining pluripotency phenotypic and functional properties. Passages were completed in stirred suspension bioreactors of increasing scale, under defined batch conditions which greatly improved resource efficiency. Output mESCs were analyzed for pluripotency marker expression (SSEA-1, SOX-2, and Nanog) through flow cytometry, and spontaneous differentiation and teratoma analysis was used to demonstrate functional maintenance of pluripotency.

关键词： Anaerobic Membrane Bioreactor (AnMBR)   Cheese whey   Cattle slurry   Energy recovery   Microbial community   Water recovery  

摘要： A single-stage Anaerobic Membrane Bioreactor (AnMBR) for the treatment of cheese whey and its co-digestion with cattle slurry was investigated with the aim of potentially recovering water and energy from the wastewater. A 9 L reactor coupled to an ultrafiltration flat sheet membrane module in an external configuration was employed. This configuration enabled the proper separation of solids from permeate. Cheese whey was stored at room temperature and its chemical oxygen demand (COD) varied between 51 and 80 g/L. The reactor was operated at an average hydraulic retention time (HRT) of 15 days and at an organic loading rate (OLR) of 1.2-8.4 kg COD/(m(3).day). During operation a COD removal average of 91% 7% was achieved. The biogas production ranged from 0.2 to 0.9 m(3) biogas/kg COD removed and its methane content was 51-73%. From these results, a potential energy recovery of 2.4 kWh/kg COD removed was calculated. Microbial community analysis showed that bacteria belonging to the orders Bacteroidales and Clostridiales became the most prevalent. The bioreactor was dominated by acetotrophic methanogenesis. The co-digestion of cheese whey with cow manure (3:1) did not decrease NaOH consumption for pH control. Water reuse for cleaning purposes is possible if permeate pH is maintained at 6. Prior to the scaling-up of the system, a pilot scale test would be necessary to optimise membrane performance. The use of AnMBR technology at a real scale would be appropriate since it is a compact technology which permits both energy and potential water recovery after permeate post-treatment, thus constituting a further step towards the establishment of a broader a circular economy approach.