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关键词： Membrane bioreactor   Virus removal modeling   HACCP   Soft-sensor approach   Process-driven modeling   Data-driven modeling  

摘要： The increasing pressure on the global water supply calls for more advanced solutions with higher efficiency and better sustainability, leading to the promptly developing water reclamation and reuse schemes including treatment technologies and risk management strategies where microbial safety is becoming a crucial aspect in the interest of public health. Backed up by the development of membrane technology, membrane bioreactors (MBR) have received substantial attention for their superiority over conventional treatment methods in many ways and are considered promising in the water reclamation realm. This review paper provides an overview of the efforts made to manage and control the potential waterborne viral disease risks raised by the use of effluent from MBR treatment processes, including the mechanisms involved in the virus removal process and the attempts to model the dynamics of the removal process. In principle, generalized and integrated virus removal models that provide insight into real-time monitoring are urgently needed for advanced real-time control purpose. Future studies of approaches that can well handle the inherent uncertainty and nonlinearity of the complex removal process are crucial to the development and promotion of related technologies. (C) 2020 The Authors. Published by Elsevier Ltd.

关键词： 膜生物反应器   活性炭   膜污染   处理效率  

摘要： 通过投加粉末活性炭(PAC)/颗粒活性炭(GAC)改善污泥混合液性质从而减缓膜污染是膜生物反应器(MBR)领域的研究热点,重点介绍了最近五年有关活性炭与MBR结合处理不同类型废水的研究进展,投加PAC/GAC对MBR处理能力的影响,对减缓膜污染的作用,尤其是结合动态膜(DM)论述对污泥性质的改善。重点讨论了活性炭在好氧和厌氧膜生物反应器中的作用差异。并展望了微生物高通量测序技术,数学模型在活性炭强化MBR性能研究领域的必要性以及活性炭与其他技术方法联用的可行性。

关键词： 膜生物反应器   NaClO清洗   消毒副产物   临界加氯量   膜污染  

摘要： 水资源短缺及其污染已经成为全世界各国亟需解决的重要问题，膜生物反应器(MBR)作为一种科学有效的水处理工艺广泛应用于污水、废水处理和水资源再生领域，然而伴随MBR产生的膜污染现象会大幅降低膜的通量并提高运行成本，限制了MBR工艺进一步普及和发展。\n 次氯酸钠(NaClO)定期化学清洗是恢复MBR膜通量的主要手段。然而，膜污染物的氯化会产生大量具有三致毒性的消毒副产物(DBPs)，导致MBR出水水质恶化，并且诱发或增加MBR池内细菌的耐药性。本文研究了MBR膜组件NaClO化学清洗过程中14种DBPs的生成特性和毒性，探究了清洗时间、NaClO浓度、清洗剂初始pH值和清洗温度对DBP生成和毒性的影响，基于胞外聚合物(EPS)在生物膜结构和组成中的支撑性作用，分析了EPS对NaClO膜化学清洗DBPs生成的影响和作用机制;最后，基于上述研究结果，从优化膜清洗工艺条件和调控膜表面生物膜细菌生理特性两个角度入手，研究了MBR膜NaClO化学清洗过程中DBPs的控制方法。\n 研究结果表明，在经过含氯量为1000mg/L的NaClO溶液中清洗24h后生成的DBPs中，卤乙酸(HAAs)都是生成量最多的消毒副产物，浓度可达到3000μg/L，占总DBPs的80％以上，其中三氯乙酸(TCAA)占了主导地位，以三氯甲烷(TCM)为主的THMs的浓度往往也能达到数百微克升，而相对不稳定的卤乙腈(HANs)、卤代丙酮(HKs)和三氯硝基甲烷(TCNM)在中性条件下的浓度都小于70μg/L，甚至在碱性条件下均小于检测限。随着NaClO清洗时间的延长，DBPs中的HAAs和TCM积累量逐渐提高。增加NaClO的用量、提高温度和pH值，TCM和二氯乙酸(DCAA)的产率增加了1-14倍，而卤代乙腈(HANs)和卤代酮(HKs)的产率降低20％以上，甚至在碱性条件下降至检出限以下。降低氯投加量和清洗温度，或将清洗剂的pH值调整为酸性或碱性均可有效降低12％-43％的DBPs毒性风险。将NaClO与酸、碱联合使用模拟实际清洗工艺，1000mg/LNaClO与0.1％柠檬酸混合作为清洗剂产生的DBPs最多，而NaClO与1％NaOH混合作为清洗剂产生的DBPs最少。\n 将MBR膜表面污染物进行EPS提取预处理后，由于生物膜结构的破坏，在膜清洗的前6h内DBPs的生成速度提高了18％左右。在污染的MBR膜组件NaClO清洗过程中，膜表面生物膜EPS贡献了15％-18％的DBPs总产量。共聚焦激光扫描显微镜(CLSM)图像显示，膜表面生物膜EPS是限制膜清洗效率的关键因素，一方面，胞外蛋白质具有很高的氯反应活性，会快速消耗氯;另一方面，胞外多糖对氯有很强的抵抗力，可以阻碍氯渗透生物膜，对氯化作用下的MBR膜表面生物膜和细菌有保护作用;此外，生物膜EPS分布不均匀，一些结构特殊的区域对氯化有特别强的抵抗，经过长时间的化学清洗也能残留在膜表面。\n 分别对从污泥细菌中提取的内源有机物(IOM)和胞外聚合物(EPS)进行24h氯消毒实验发现，总有机碳(TOC)为1mg的IOM的TCM生成潜力是181μg/L，是EPS的五倍，甚至在EPS完全无法生成HANs类副产物的时候，IOM都可以与NaClO反应生产大量的三氯乙腈(TCAN)和二氯乙腈(DCAN)。毒性风险分析结果表明，IOM氯化成的DBPs的总毒性风险值比EPS高近百倍。\n 次氯酸钠对污泥细菌的杀灭存在临界浓度，在临界浓度之下的次氯酸钠短时间接触无法让细菌破裂释放出IOM。以自由氯浓度/MLSS=1为条件对污泥进行反应后，污泥中的细菌结构和活性均未发生变化，没有IOM的释放。并且DBPs生成和组成分析也发现，在1mg/LCl2/mgMLSS有效氯投加条件下，基本没有HANs等不稳定DBPs生成，且TCM的生成量也比10mg/LCl2/mgMLSS加氯量条件下降低了91％，生成的DBPs总毒性仅为50mg/LCl2/mgMLSS加氯量条件下的8.8％。D-氨基酸预处理实验表明，采用30μM的D-酪氨酸预处理即可使铜绿假单胞菌的纯菌膜出现明显裂解，有助于提高后续氯清洗效率。由此可见，采用高频率、低氯量化学清洗并结合D-氨基酸预清洗的方式，来控制DBPs的生成，降低MBR膜化学清洗造成的健康威胁和环境风险。

关键词： 厌氧膜生物反应器   纳滤   反渗透   印染废水   容积负荷   膜污染  

摘要： 采用厌氧膜生物反应器-纳滤/反渗透(AnMBR-NF/RO)组合工艺处理实际印染废水.结果表明,在COD容积负荷0.65～2 g/(L·d)条件下,AnMBR的COD和色度去除率分别可达90％和95％;在低膜通量(0.85～3.4 L/(m2·h))条件下,无显著膜污染发生.AnMBR出水经恒压错流NF/RO过滤深度处理,当NF出水回收率76.2％时,出水COD为49.5 mg/L,NH4+-N、TN、TP 的质量浓度分别为 14.5、29.6、0.93 mg/L,电导率5.76 mS/cm,满足GB 4287-2012印染废水间接排放和CJ 25.1-89生活杂用水标准.当RO出水回收率72.6％时,出水COD为4.4 mg/L,NH4+-N、TN、TP的质量浓度分别为4.9、10.1、0.50mg/L,电导率0.284 mS/cm,满足印染废水直接排放、生活杂用水和FZ/T 01107-2011印染工业漂洗水回用标准.NF/RO过滤过程中滤饼层为主导膜污染机理且RO污染潜势显著高于NF.

关键词： Two-phase flow   Bubble formation   Viscosity   Bubble shape   Dimensionless numbers   Shape regime  

摘要： The generation and formation characteristics of air bubbles have significant impact on the performance of the membrane bioreactor system. Experiments were conducted in a tank filled with Glycerine-Water solutions so as to investigate the impacts of liquid viscosity on the bubble formation characteristics. Nozzle size ranging from 2 to 10 mm, air inlet flow rate ranging from 300 to 1500 cc/min and liquid viscosity ranging from 6 to 850 cP have been investigated. Methods to compute the non-linear characteristics such as bubble diameter and bubble rising velocity have been identified. The nonlinear behaviour of the air bubbles were further correlated to the dimensionless numbers such as Reynolds number, EOtvOs number and Galilei number. A bubble shape regime was constructed so as to classify the distinct regions of the air bubbles generated from different viscous solutions. Coalescence of bubbles were studied extensively and the impact of liquid viscosity on the bubble flow regimes were presented.

关键词： Anaerobic digestion   AnMBR   Municipal wastewater   Demonstration, biogas   Mass balance  

摘要： The aim of this work was to demonstrate the operation of a large pilot-scale submerged anaerobic membrane bioreactor (5.0 m(3)) for biogas production from municipal wastewater at ambient temperature of 25 degrees C. To the best of our knowledge, this is the largest one-stage submerged AnMBR that has ever been reported. This AnMBR realized a hydraulic retention time (HRT) of 6 h and a treatment capacity of 20 m(3) d(-1), obtaining excellent effluent quality with COD removal efficiency over 90% and BOD5 removal over 95%. The biogas yield of the AnMBR was 0.25-0.27 L g(-1) removed COD and 0.09-0.10 L L-1 raw wastewater. The methane content of the biogas was at the range of 75%-81%. The COD and nitrogen mass balance were also identified based on longterm operation. The hollow-fiber membrane module realized a flux of 2.75-17.83 LMH. An online backwash chemical cleaning system helped to lower the transmembrane pressure timely.

关键词： Membrane bioreactor   Membrane fouling   Soluble microbial products   Sludge flocs   Microbial fuel cell  

摘要： This study focused on the fouling characteristics evaluation of the sludge in a membrane bioreactor integrated with microbial fuel cell (MFC-MBR) to reveal the mechanisms of membrane fouling mitigation. The filtration of soluble microbial products (SMPs) in MFC-MBR showed lower flux decline rate than those in the control system (C-MBR). Based on the extended Derjaguin-Landau-Verwey-Overbeek analysis, decreases in free energies of adhesion between the SMPs and clean membrane or SMP-fouled membrane were observed in MFC-MBR. When approaching the clean membrane or SMP-fouled membrane, the SMPs in MFC-MBR had to overcome a higher energy barrier compared to those in CMBR, indicating the inhibition of adsorption of SMPs on the membrane surface in MFC-MBR. Additionally, sludge flocs in MFC-MBR exhibited lower hydrophobicity and were less negative surface charged in comparison to those in the C-MBR. In MFC-MBR, the sludge flocs approaching the clean membrane, SMP-fouled membrane and cake layer all experienced higher energy barriers and lower secondary energy minimums compared to those in C-MBR, exhibiting the lower potential of cake layer formation. These results confirmed that decreases of the fouling potentials of SMPs and sludge flocs were essential for the membrane fouling mitigation in the MFC-MBR. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Stage-top bioreactor   Mechanical stimulation   PDMS diaphragm   Nano-pattern   Maturation   Cardiac cells  

摘要： Over the years, several in-vitro biosensing platforms have been developed for enhancing the maturation of the cultured cells. However, most of the proposed platforms met with limited success due to its inability for live-cell imaging, complicated fabrication, and not being advantageous from an economic perspective due to a higher price. To overcome the drawbacks of the current state-of-the-art, herein, we developed a next-generation stage top incubator (STI) incorporated with nano grooves patterned PDMS diaphragm (NGPPD). The proposed device consists of a miniatured STI, the NGPPD functional well plates, and a mechanical stimulator. A thin layer of gold (Au) is deposited on the NGPPD to enhanced myogenic differentiation, cell maturation, and cell-cell interactions. The nano grooves are integrated on the PDMS surface to align the cardiomyocytes in the grooved direction during the culture period. The cardiomyocytes cultivated on the Au-deposited NGPPD are stimulated topographically and mechanically during the cultivation period. The enhanced cardiomyocytes maturation cultured on the Au-deposited NGPPD is experimentally demonstrated using immunofluorescence staining and PCR analysis.

关键词： Synthetic wastewater   Hospital wastewater   Illumina high throughput sequencing   Micro-eukaryotes community  

摘要： This study was performed to understand the dynamics of the microbial community of submerged membrane bioreactor during the acclimatization process to treat the hospital wastewater. In this regard, three acclimatization phases were examined using a mixture of synthetic wastewater (SWW) and real hospital wastewater (HWW) in the following proportions;In Phase 1: 75:25 v/v (SWW: HWW);Phase 2: 50:50 v/v (SWW: HWW);and Phase 3: 25:75 v/v (SWW: HWW) of wastewater. The microbial community was analyzed using Illumina high throughput sequencing to identify the bacterial and micro-eukaryotes community in SMBR. The acclimatization study clearly demonstrated that shift in microbial community composition with time. The dominance of pathogenic and degrading bacterial communities such as Mycobacterium, Pseudomonas, and Zoogloea was observed at the phase 3 of acclimatization. This study witnessed the major shift in the micro-eukaryotes community, and the proliferation of fungi Basidiomycota was observed in phase 3 of acclimatization.

关键词： Anaerobic digestion   Anaerobic membrane bioreactor (AnMBR)   Water resource recovery facility (WRRF)   Plant-wide assessment   Techno-economic analysis  

摘要： This research evaluated the economic feasibility of anaerobic membrane bioreactor (AnMBR) as a mainstream technology for municipal sewage treatment. To this end, different wastewater treatment plant (WWTP) layouts were considered, including primary settler, AnMBR, degassing membrane, partial nitritation-Anammox, phosphorus precipitation and sidestream anaerobic digestion. The net treatment cost of an AnMBR-WWTP decreased from 0.42 to 0.35 Euro m(3) as the sewage COD concentration increased from 100 to 1100 mg COD L-1 due to revenue from electricity production. However, the net treatment cost increased above 0.51 Euro m(3) when nutrient removal technologies were included. The AnMBR and partial nitritation-Anammox were the costliest processes representing a 57.6 and 30.3% of the treatment cost, respectively. Energy self-sufficiency was achieved for high strength municipal sewage treatment (1000 mg COD L-1) and a COD:SO42--S ratio above 40. Overall, the results showed that mainstream AnMBR has potential to be an economically competitive option for full-scale implementation.