课程文献中心 更多>>

关键词： Biofouling   Membrane bioreactor   Quorum quenching dose   Sheet media   Signal molecule  

摘要： Quorum quenching (QQ) has been recognized as an emerging anti-biofouling strategy for membrane bioreactors (MBRs), but studies on effective QQ bacterial doses are needed. Therefore, in this study, the QQ efficacy for sheet-type media containing different amounts of QQ bacteria (i.e., Rhodococcus sp. BH4) with respect to biofouling control during MBR treatment of synthetic and real municipal wastewaters was investigated. The QQ sheets with well-embedded BH4 bacteria were distinctly effective at alleviating biofouling, but their efficacy was highly dependent on the QQ bacterial dose. The activity of the QQ sheet increased with the QQ bacterial density and its pseudo-first order rate constant reached 3.52 h(-1) with 100 mg BH4 per liter of reactor volume. No QQ activity loss occurred with long-term use of the QQ sheets. The relationship between QQ dose and fouling delay had a strong, linear correlation. Fouling retardation was more pronounced with real wastewater because it had less biofouling propensity owing to its inferior organics and nutrients. In fact, the MBRs fed with real wastewater experienced a dramatic decrease in extracellular polymeric substance (EPS) content responsible for biofouling. QQ suppressed the EPS secretion leading to fouling mitigation, but with no impact on biological treatment performances.

关键词： AnMBR   Salinity   Phenol   Microbial community   Sodium   Wastewater treatment  

摘要： Industrial wastewaters are becoming increasingly associated with extreme conditions such as the presence of refractory compounds and high salinity that adversely affect biomass retention or reduce biological activity. Hence, this study evaluated the impact of long-term salinity increase to 20 gNa(+).L-1 on the bioconversion performance and microbial community composition in anaerobic membrane bioreactors treating phenolic wastewater. Phenol removal efficiency of up to 99.9% was achieved at 14 gNa(+).L-1. Phenol conversion rates of 5.1 ***(-1).d(-1), 4.7 ***(-1).d(-1), and 11.7 ***(-1).d(-1) were obtained at 16 gNa(+).L-1,18 gNa(+1).L-1 and 20 gNa(+).L-1, respectively. The AnMBR's performance was not affected by short-term step-wise salinity fluctuations of 2 gNa(+).L-1 in the last phase of the experiment. It was also demonstrated in batch tests that the COD removal and methane production rate were higher at a K+:Na+ ratio of 0.05, indicating the importance of potassium to maintain the methanogenic activity. The salinity increase adversely affected the transmembrane pressure likely due to a particle size decrease from 185 mu m at 14 gNa(+).L-1 to 16 mu m at 20 gNa(+).L-1. Microbial community was dominated by bacteria belonging to the Clostridium genus and archaea by Methanobacterium and Methanosaeta genus. Syntrophic phenol degraders, such as Pelotomaculum genus were found to be increased when the maximum phenol conversion rate was attained at 20 gNa(+).L-1. Overall, the observed robustness of the AnMBR performance indicated an endured microbial community to salinity changes in the range of the sodium concentrations applied. (C) 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

关键词： Osmotic membrane bioreactor   Bioelectrochemical system   Reverse solute flux   Resource recovery   Wastewater  

摘要： A key challenge for osmotic membrane bioreactors (OMBRs) application is reverse solute flux and consequent salt accumulation in the feed side. Herein, a bioelectrochemical system (BES) was employed to drive reverse-fluxed solutes from the feed of an OMBR into a cathode compartment for recovery and subsequent reuse as a draw solute (DS). Compared to an OMBR without BES function, the present OMBR system enhanced water recovery from 925 to 1688 mL and increased the chemical oxygen demand (COD) removal efficiency from 40.2 +/- 8.1 to 75.2 +/- 3.3%, benefited from its lower anolyte conductivity of 9.0 mS cm(-1) than that of the control system (24.1 mS cm(-1)). The CO2 addition significantly improved the ammonia recovery rate to 93.3-116.7 g N m(-3) h(-1) (or 248.0-307.4 g N m(-2) d(-1)),12.1-14.5 times higher than that without CO2 addition. The recovered DS was successfully applied to accomplish water extraction in the reuse test, and such a recovery/reuse process could result in a normalized water recovery of 3870 mL mol DS-1 or a DS usage of 0.26 mol L-1 (of the recovered water). The energy consumption of the system might be compensated by the production of bioenergy, and the net specific energy consumption was estimated to be 0.004-0.112 kWh m(-3) wastewater, 0.007-0.179 kWh kg(-1) removed COD, or 0.001-0.020 kWh kg(-1) recovered NH4+-N. Those results have demonstrated that bioelectrochemical processes can be an effective approach for in situ mitigation of reverse-fluxed solute in OMBR and recovering "the lost DS" towards both reuse and reduced operational expense. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Thapsia garganica   Thapsigargin   Nortrilobolide   In vitro shoot cultures   Temporary immersion bioreactor   Sesquiterpenes   TgTPS2 and TgCYP76AE2  

摘要： Background: Thapsigargin and nortrilobolide are sesquiterpene lactones found in the Mediterranean plant Thapsia garganica L. Thapsigargin is a potent inhibitor of the sarco/endoplasmic reticulum calcium ATPase pump, inducing apoptosis in mammalian cells. This mechanism has been used to develop a thapsigargin-based cancer drug first by GenSpera and later Inspyr Therapeutics (Westlake Village, California). However, a stable production of thapsigargin is not established. Results: In vitro regeneration from leaf explants, shoot multiplication and rooting of T. garganica was obtained along with the production of thapsigargins in temporary immersion bioreactors (TIBs). Thapsigargin production was enhanced using reduced nutrient supply in combination with methyl jasmonate elicitation treatments. Shoots grown in vitro were able to produce 0.34% and 2.1% dry weight of thapsigargin and nortrilobolide, respectively, while leaves and stems of wild T. garganica plants contain only between 0.1 and 0.5% of thapsigargin and below detectable levels of nortrilobolide. In addition, a real-time reverse transcription PCR (qRT-PCR) study was performed to study the regulatory role of the biosynthetic genes HMG-CoA reductase (HMGR), farnesyl diphosphate synthase (FPPS), epikunzeaol synthase (TgTPS2) and the cytochrome P450 (TgCYP76AE2) of stem, leaf and callus tissues. Nadi staining showed that the thapsigargins are located in secretory ducts within these tissues. Conclusions: Shoot regeneration, rooting and biomass growth from leaf explants of T. garganica were achieved, together with a high yield in vitro production of thapsigargin in TIBs.

关键词： 膜生物反应器   废水处理系统   废水处理方法   膜分离系统   曝气系统   产水系统   溶解氧浓度   物理分区  

摘要： 一种采用膜生物反应器的废水处理方法和系统，包括：控制曝气使溶解氧浓度为0～1．5mg／L，保持反应器处于兼性环境。膜反应器废水处理系统无物理分区，包含反应器、膜分离系统、产水系统和曝气系统。膜分离系统置于反应器内部，产水系统联通膜分离系统泵滤出水。曝气系统用于对反应器和膜分离系统曝气。

关键词： Semi-passive treatment   Bioremediation   Subarctic   Zinc   Cadmium   Sulfate-reducing bacteria  

摘要： Mine drainage contaminated with metals is a major environmental threat since it is a source of water pollution with devastating effects on aquatic ecosystems. Conventional active treatment technologies are prohibitively expensive and so there is increasing demand to develop reliable, cost-effective and sustainable passive or semi-passive treatment. These are promising alternatives since they leverage the metabolism of microorganisms native to the disturbed site at in situ or close to in situ conditions. Since this is a biological approach, it is not clear if semi-passive treatment would be effective in remote locations with extremely cold weather such as at mines in the subarctic. In this study we tested the hypothesis that sulfate-reducing bacteria, which are microorganisms that promote metal precipitation, exist in subarctic mine environments and their activity can be stimulated by adding a readily available carbon source. An experiment was setup at a closed mine in the Yukon Territory, Canada, where leaching of Zn and Cd occurs. To test if semi-passive treatment could precipitate these metals and prevent further leaching from waste rock, molasses as a carbon source was added to anaerobic bioreactors mimicking the belowground in-situ conditions. Microbial community analysis confirmed that sulfate-reducing bacteria became enriched in the bioreactors upon addition of molasses. The population composition remained fairly stable over the 14 month operating period despite temperature shifts from 17 to 5 degrees C. Sulfate reduction functionality was confirmed by quantification of the gene for dissimilatory sulfite reductase. Metals were removed from underground mine drainage fed into the bioreactors with Zn removal efficiency varying between 20.9% in winter and 89.3% in summer, and Cd removal efficiency between 39% in winter and 90.5% in summer. This study demonstrated that stimulation of native SRB in MIW was possible and that in situ semi-passive treatment can be effe

关键词： 废水处理方法   膜生物反应器   电化学   厌氧   活性微生物   产电微生物   输入设备   膜电极  

摘要： 一种厌氧电化学膜生物反应器（AnE MBR）,包括废水输入设备,设备中安置了有电化学活性微生物的阳极电极（EAB,也指阳极还原菌、产电细菌和产电微生物）,其可氧化废水中的有机物。设备中还包括阴极膜电极,用于过滤废水,同时维持电化学活性微生物和氢营养型产甲烷菌的活性,阴极膜电极用于催化析氢反应产氢。

关键词： Membrane bioreactor   Self-forming dynamic membrane   Permeate deterioration   Dynamic layer compression  

摘要： The self-forming dynamic membrane bioreactor (SFDMBR) is a biological wastewater treatment technology based on the conventional membrane bioreactor (MBR) with membrane material modification to a large pore size (30-100 mu m). This modification requires a dynamic layer formed by activated sludge to provide effective filtration function for high-quality permeate production. The properties of the dynamic layer are therefore important for permeate quality in SFDMBRs. The interaction between the structure of the dynamic layer and the performance of SFDMBRs is little known but understandably complex. To elucidate the interaction, a lab-scale SFDMBR system coupled with a nylon woven mesh as the supporting material was operated. After development of a mature dynamic layer, excellent solid-liquid separation was achieved, as evidenced by a low permeate turbidity of less than 2 NTU. The permeate turbidity stayed below this level for nearly 80 days. In the fouling phase, the dynamic layer was compressed with an increase in the trans-membrane pressure and the quality of the permeate kept deteriorating until the turbidity exceeded 10 NTU. The investigation revealed that the majority of permeate particles were dissociated from the dynamic layer on the back surface of the supporting material, which is caused by the compression, breakdown, and dissociation of the dynamic layer. This phenomenon was observed directly in experiment instead of model prediction or conjecture for the first time. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Antibiotic resistance genes   Sustainable wastewater treatment   Wastewater bypass   Denitrification   High-throughput qPCR  

摘要： Inadequate sanitation can lead to the spread of infectious diseases and antimicrobial resistance (AMR) via contaminated water. Unfortunately, wastewater treatment is not universal in many developing and emerging countries, especially in rural and peri-urban locations that are remote from central sewers. As such, small-scale, more sustainable treatment options are needed, such as aerobic-Denitrifying Downflow Hanging Sponge (DDHS) bioreactors. In this study, DDHS reactors were assessed for such applications, and achieved over 79% and 84% removal of Chemical Oxygen Demand and Ammonium, respectively, and up to 71% removal of Total Nitrogen (TN) from domestic wastes. Elevated TN removals were achieved via bypassing a fraction of raw wastewater around the top layer of the DDHS system to promote denitrification. However, itwas not known how this bypass impacts AMR gene (ARG) and mobile genetic element (MGE) levels in treated effluents. High-throughput qPCR was used to quantify ARG and MGE levels in DDHS bioreactors as a function of percent bypass (0, 10, 20 and 30% by volume). All systems obtained over 90% ARG reduction, although effluent ARG and TN levels differed among bypass regimes, with co-optimal reductions occurring at similar to 20% bypass. ARG removal paralleled bacterial removal rate, although effluent bacteria tended to have greater genetic plasticity based on higher apparent MGE levels per cell. Overall, TN removal increased and ARG removal decreased with increasing bypass, therefore co-optimization is needed in each DDHS application to achieve locally targeted TN and AMR effluent levels. (C) 2018 Elsevier B.V. All rights reserved.

关键词： 太阳能利用   风能利用   农村生活污水   生物接触氧化法  

摘要： 农村生活污水处理设施能耗高难以长效运行,目前已有利用太阳能和风能供电驱动污水处理设施的研究和应用,但常规的太阳能和风能发电设施需要用蓄电池组稳定电能的输出,而蓄电池的使用寿命短导致成本增加,也增加了环境污染风险。为降低成本,减少环境污染风险,通过对不同季节太阳能和风能强度变化监测与分析,确定太阳能与风能具有季节互补性。在此基础上,将太阳能辐射强度周期性、农村生活污水排放不连续性、污水生物处理过程对溶解氧需求的差异三者融合,提出了一种无蓄电池组的太阳能与风能互补发电驱动农村生活污水生物处理设施的集成系统,可降低运行和维护费用。167 d的连续运行实验结果表明:通过自动控制系统的调控及建立相应的生物反应器运行工况,可以实现发电单元电能输出稳定,且能源利用率达到80%;生物反应器对COD、NH_4^+-N和TN的平均去除率分别为90.6%、94.7%和61.7%,出水平均浓度分别为29.1、2.1和15.8 mg·L^(-1)。研究结果证明利用无蓄电池风-光能互补驱动生物反应器处理农村生活污水是可行的。