进水盐度对膜生物反应器运行效能的影响研究

进水盐度对膜生物反应器(MBR)的运行效能影响显著,尤其是进水含盐量为5 g/L时,明显恶化了污泥可滤性,膜污染速率加快;MBR混合液中溶解性微生物产物(SMP)和胞外聚合物(EPS)含量随钠离子浓度变化而变化,其中SMP中蛋白质含量与钠离子浓度密切相关;与紧密结合态EPS(TB)相比,钠离子含量对松散结合态EPS(LB)浓度的影响更大;不同盐度对COD及NH4+-N影响不明显,系统对COD及NH4+-N的去除效果稳定,分别保持在92%及94%以上,高盐度对MBR总磷去除率降低明显。     

不同价态铁离子对膜生物反应器影响研究进展

膜生物反应器(Membrane bioreactor,MBR)作为一种新型的污水处理技术,近些年来备受关注。然而,膜污染问题成为了该工艺广泛应用的最大障碍。现已证明,向MBR中投加铁系混凝剂能够减缓膜污染。本文首先综述了不同价态铁离子对MBR污染物去除的影响,然后对铁离子在污泥混合液中分布及迁移转化进行了分析,接着阐明了铁离子对膜污染的影响,最后对该领域的研究进行了展望。     

Fe3+对MBR减缓膜污染的研究进展

膜生物反应器(membrane bioreactor, MBR)作为一种高效的污水处理及回用工艺,比传统的活性污泥法具有更多优势。然而,膜污染问题是限制其广泛应用的关键性问题。众多研究者已证实Fe₃₊能有效的改善MBR中混合液的可滤性及减缓膜污染。本文简述了MBR污泥混合液中主要污染物—胞外聚合物(extracellular polymeric substances, EPSs),并总结Fe₃ 在去除混合液中污染物、减缓膜污染方面的效能及其对污泥混合液的影响。最后,对Fe₃ 在减缓MBR膜污染的未来研究方向进行展望。     

膜生物反应器中AHL分析技术研究进展

膜生物污染一直是膜生物反应器(membrane bioreactor,MBR)在废水处理工艺中需要解决的一大难题。最近研究表明：基于群体感应的淬灭技术可以作为MBR活性污泥体系中一种有效的膜生物污染防治策略。因而,识别和分析群体感应产生的信号分子是应用群体淬灭技术防治MBR中膜生物污染的关键。本文首先介绍了活性污泥体系中的群体感应机理和N-酰基高丝氨酸内脂(N-acyl homoserine lactone,AHL);其次,归纳近期研究中针对MBR中AHL定性和定量分析方法;最后,对MBR中AHL识别及分析技术应用进行了展望。     

膜生物反应器在废水处理中的应用及研究

膜生物反应器是将生物反应器与膜分离技术相结合的一种高效废水处理新技术。介绍了膜生物反应器的类型、特点以及其在处理生活污水、工业废水、垃圾渗透液、粪便污水和中水回用中的研究和应用现状,提出了膜生物反应器所存在的问题及其研究进展。     

基于XDLVO理论解析MBR膜污染研究进展

膜污染问题严重制约了膜生物反应器(MBR)的广泛应用,因此膜污染机制的研究对于有效控制膜污染十分重要。XDLVO理论合理地解析了范德华力、极性作用力、双电层作用力在膜污染过程中的贡献,有效地揭示了膜污染机理。本文首先阐述了XDLVO理论;然后运用XDLVO理论,解析界面微距离范围内膜表面凝胶层及泥饼层形成过程;最后总结了XDLVO理论在MBR膜污染方面的应用,并对该领域未来的研究方向进行了展望。     

酶膜反应器及其在生物催化领域的应用

酶膜反应器是一种新型的生物催化反应设备,它是反应与分离相耦合的装置,集产品分离、纯化和酶回收利用于一体,具有其它方法不可比拟的优势。在强调资源节约,环境友好和清洁化生产技术的今天,显示一些特别的优点,近年来已成为热门的研究领域。本文主要介绍了酶膜反应器的基本原理、特征及其分类,并根据分类对近年来酶膜反应器在生物催化领域的应用研究进行了概述,同时对酶膜反应器存在的问题和发展趋势做了分析和展望。     

无机膜反应器对丙烷芳构化历程的影响

根据实验结果,从理论上分析了Ａｌ２Ｏ３无机膜反应器对ＨＺＳＭ－５,０．４％Ｇａ／ＨＺＳＭ－５和０．５％Ｐｔ－０．４％Ｇａ／ＨＺＳＭ－５催化剂上丙烷芳构化反应历程的影响。结果表明,氢气在烷烃活化、环烃形成芳烃和低碳烯烃加氢过程中担当着重要角色,膜反应器通过影响这些步骤,进而影响整个芳构化反应的选择性。     

COMSOL软件在枸杞多糖超滤膜生物反应器中膜阻塞模型构建中的应用

基于聚砜中空纤维超滤膜分离技术精制枸杞多糖（Lycium barbarum polysaccharide）,通过COMSOL软件对枸杞多糖膜阻塞逆流提取及超声设备参数进行修正,获得更优的纯化工艺。采用微波-超声法提取枸杞多糖,并利用聚砜中空纤维超滤膜对枸杞多糖进行分离,采用单因素分析及正交实验考察枸杞多糖提取和分离过程中的重要参数,通过COMSOL软件对重要膜阻塞参数进行修正。结果表明,枸杞多糖提取较优工艺条件为：提取温度50~70 ℃之间,超声功率50 W,固液比例1∶8~1∶12（mg∶mL）,提取时间40~60 min;当超滤膜截留相对分子质量为1×10⁴时,膜通量较好;正交实验结果表明,膜通量与料液温度关系最大,其次是膜pH值和分离操作压;COMSOL软件对枸杞多糖连续逆流提取设备进行仿真计算,结果发现与全封闭叶片相比,开孔叶片能够显著降低溶剂短路现象,使得最低流速提升高达65倍。基于COMSOL软件数据修订,枸杞多糖分离效率得到大幅度提升,为枸杞多糖工业化生产提供必要的数据积累。     

离子交换膜对采用生物膜电极法降解五氯酚的影响

以五氯酚（PCP）为目标污染物,在隔膜式电解槽中研究了不同离子交换膜对采用生物膜电极法处理五氯酚的影响. 结果表明,阴离子交换膜有利于五氯酚在生物膜电极上的转化和中间产物的去除;与生物法和电化学法降解五氯酚相比,采用以钛基二氧化铅为阳极（Ti/PbO₂）、生物膜电极为阴极、阴离子交换膜为隔膜的电解槽处理时,五氯酚的降解效果明显优于生物法和电化学方法,经24 h处理后五氯酚的去除率和化学需氧量（COD）去除率均可达到96%（质量分数）.     

Periodic air/water cleaning for control of biofouling in spiral wound membrane elements

The main problem during the operation of nanofiltration or reverse osmosis membrane plants is fouling of feed spacers in membrane elements due to biofouling and particulate fouling. In order to control biofouling and particulate fouling in membrane elements, both daily air/water cleaning (AWC) and daily copper sulphate dosing (CSD) were investigated and compared to a reference without daily cleaning. A pilot study was carried out for 110 days with three parallel spiral wound membrane elements; AWC, CSD and the reference which were fed by tap water enriched with a biodegradable compound (100 μg acetate-C/L). The CSD element, which combined daily copper sulphate dosing and sporadically air/water cleaning, performed best with an increase in pressure drop of 18% and a biomass concentration of 8000 pg ATP/cm² within 110 days. This was followed by the AWC element with a pressure increase of 37% and biomass concentration of 20,000 pg ATP/cm² within 110 days. The reference element showed a pressure increase of 120% within 21 days. The presented approach is considered very successful in controlling particulate fouling and biofouling, especially when air/water cleaning is combined with copper sulphate dosing.     

Behavior of extracellular polymers and bio-fouling during hydrogen fermentation with a membrane bioreactor

The characteristics of membrane fouling were investigated by examining the behaviors of extracellular polymer substances (EPSs) produced by hydrogen-producing bacteria during hydrogen fermentation from a submerged membrane bioreactor (MBR). The MBR consisted of a 1.4-L submerged membrane filtration tank and 3-L hydrogen fermenter. An intermittent suction operation was selected to maintain stable filtration performance. The operation of the suction pump was alternately shifted to ON for 7 min followed by OFF for 3 min, with bio-gas sparging at a flow rate of 5.0 L/m²/h (LMH), and manually regulated. Most of the EPS during the continuous hydrogen fermentation using an MBR had accumulated in the reactor because they were retained by the membrane by adsorption onto the polymeric membrane surface. The amount of proteins in the EPS extracted was increased to 179 mg/L and that of carbohydrates was increased to 58 mg/L. Cu²⁺, Mg²⁺, Zn²⁺ in the EPS were increased in the range of 1.6–3.3 mg/L. The high concentration of EPS that is produced has a higher chelation potential in the formation of ligand complexes with metals or cations than that in a conventional continuous stirred tank reactor (CSTR). The EPS directly affected the decrease in the permeate flux, which resulted in the clogging of the membrane.     

Use of submerged anaerobic–anoxic–oxic membrane bioreactor to treat highly toxic coke wastewater with complete sludge retention

Coke wastewater is an extremely toxic industrial effluent that requires treatment before discharge. A bench-scale, anaerobic–anoxic–oxic membrane bioreactor (A₁/A₂/O-MBR) system was utilized to treat real coke wastewater with complete sludge retention. In a 160-d test, the A₁/A₂/O-MBR system stably removed 87.9 ± 1.6% of chemical oxygen demand, 99.4 ± 0.3% of turbidity, and 99.7 ± 3.5% of NH₄⁺-N from coke wastewater. The membrane rejected almost all suspended solids; hence, a low food-to-microorganism environment was created to degrade refractory substances and reduce sludge production rates. The microbial diversity in the MBR system declined over time; however, neither pollutant removal efficiency nor total biological activity was adversely affected. Membrane fouling, which occurred during the operation of the MBR system, was principally resulted from the colloidal fraction of supernatant in suspension. Physical cleaning removed initial deposits of particles; however, prolonged operation resulted in severe clogging that can only be removed by chemical cleaning. An A₁/A₂/O-MBR system with short intermittent physical cleaning was recommended for coke wastewater treatment.     

Membrane fouling in a submerged membrane bioreactor (MBR) under sub-critical flux operation: Membrane foulant and gel layer characterization

Membrane foulants and gel layer formed on membrane surfaces were systematically characterized in a submerged membrane bioreactor (MBR) under sub-critical flux operation. The evaluation of mean oxidation state (MOS) of organic carbons and Fourier transform infrared (FT-IR) spectroscopy demonstrated that membrane foulants in gel layer were comprised of not only extracellular polymeric substances (EPS) (proteins, polysaccharides, etc.) but also other kinds of organic substances. It was also found that fine particles in mixed liquor had a strong deposit tendency on the membrane surfaces, and membrane foulants had much smaller size than mixed liquor in the MBR by particle size distribution (PSD) analysis. Gel filtration chromatography (GFC) analysis showed that membrane foulants and soluble microbial products (SMP) had much broader distributions of molecular weight (MW) and a larger weight-average molecular weight (M_w) compared with the influent wastewater and the membrane effluent. Scanning electron microscopy (SEM) and energy-diffusive X-ray (EDX) analysis indicated that membrane surfaces were covered with compact gel layer which was formed by organic substances and inorganic elements such as Mg, Al, Fe, Ca, Si, etc. The organic foulants coupled the inorganic precipitation enhanced the formation of gel layer and thus caused membrane fouling in the MBR.     

Characterization of exopolysaccharides in marine colloids by capillary electrophoresis with indirect UV detection

A method was established using capillary electrophoresis with indirect UV detection for analysis of monosaccharides liberated from exopolysaccharides by acidic hydrolysis. Tangential flow filtration was used to isolate high molecular weight polysaccharides from seawater. The capillary electrophoresis method included the use of a background electrolyte consisting of 2,6-dimethoxyphenol and cetyltrimethylammonium bromide. Several neutral sugars commonly existing in marine polysaccharides were separated under optimized conditions. The relative standard deviations were between 1.3% and 2.3% for relative migration time and 1.3-2.5% for peak height. Detection limits (at S/N 3) were in the range of 27.2-47.8 μM. The proposed approach was applied to the analysis of hydrolyzed colloidal polysaccharides in seawater collected from the Baltic Sea. Nanomolar levels of liberated monosaccharides in seawater samples can be detected by preconcentration up to 30,000 times.     

A new method for the evaluation of the reversible and irreversible fouling propensity of MBR mixed liquor

In this paper, a new fouling measurement method is presented as a pragmatic approach to determine a mixed liquor's fouling propensity. The MBR-VFM (VITO Fouling Measurement) uses a specific measurement protocol consisting of alternating filtration and physical cleaning steps, which enables the calculation of both the reversible and the irreversible fouling resistances. The MBR-VFM principle, set-up and measurement protocol are described as well as the evaluation of the fouling measurement method. Finally, the MBR-VFM was validated by comparing the fouling propensity measured on-line by the MBR-VFM in a lab-scale MBR with the fouling of the MBR membranes themselves. Our experiments indicated that the MBR-VFM can accurately measure fouling and that it can even be detected earlier than can be seen from the on-line filtration data of the lab-scale system itself. Furthermore, the differences measured in reversible and irreversible fouling seemed to be related to the observed impact of physical and chemical cleaning respectively. Therefore, the application of the MBR-VFM as an on-line sensor in an advanced control system, enabling the deployment of the measured fouling data for the control of membrane cleaning, seems feasible and will be tested in the near future.     

State-of-the-art of membrane bioreactors: Worldwide research and commercial applications in North America

Membrane bioreactor (MBR) technology is advancing rapidly around the world both in research and commercial applications. Despite the increasing number of studies and full-scale applications of MBR systems, directions and trends in academic research as well as commercial developments require further analysis. This paper aims to critically characterize and review worldwide academic research efforts in the area of MBRs as well as focus attention to commercial MBR applications in North America. A total of 339 research papers published in peer-reviewed international journals from 1991 to 2004 and a total of 258 full-scale MBR installations in North America were used as the database for the analysis provided in this paper. After a surge of MBR publications in 2002, research appears to have reached a plateau in the last 3 years using both submerged and external MBR units. Although much of the pioneering research occurred in Japan, France and the UK, countries such as South Korea, China and Germany have significantly contributed to the research pool in the last 5 years. The primary research focus has been on water filtration MBRs with limited growth in extractive and gas diffusion MBRs which still hold un-tapped potential. Fundamental aspects studied in academic research predominantly involve issues related to fouling, microbial characterization and optimizing operational performance. Research in North America presents a unique picture as a higher ratio of industrial wastewater treatment and side-stream MBR applications have been studied compared to other parts of the world. For MBR commercial application, the North America installations constitute about 11% of worldwide installations. Zenon occupies the majority of the MBR market in North America, whereas Kubota and Mitsubishi-Rayon have a larger number of installations in other parts of the world. Due to more stringent regulations and water reuse strategies, it is expected that a significant increase in MBR plant capacity and widening of application areas will occur in the future. Potential application areas include nitrate removal in drinking water treatment, removal of endocrine disrupting compounds from water and wastewater streams, enhancing bio-fuels production via membrane assisted fermentation and gas extraction and purification MBRs.     

Long-term study of an intermittent air sparged MBR for synthetic wastewater treatment

Membrane bioreactors (MBR) combine biological processes with membrane filtration. Advantages of MBR in municipal wastewater treatment include high effluent quality and reduced space requirements. Steady operation of membrane plants requires careful management of membrane fouling. Even though it might be impossible to prevent, fouling can be limited by techniques such as gas sparging. The injection of gas bubbles increases the shear stress and removes fouling material from the membrane surface. Most cited literature on air sparging refers to short-term experiments, often times in bench scale. The aim of this study was therefore long-term investigations in pilot plant scale of a 70 L reactor fed with glucose-based synthetic wastewater. The main focus was on enhancing permeate flux by air sparging. The results showed that using air sparging significantly increased the permeate flux was doubled even over several weeks. The findings were interpreted using the dimensionless fouling and shear stress number. The fouling resistance was found to decrease significantly with air injection ratios between 0.4 and 0.5. When air sparging was applied after a period without air sparging, the shear stress number doubled. This increase in shear led to a reduction of the fouling number by approximately 30%. During several weeks air sparging only a slow fouling number increase was. In contrast to that after air sparging was ceased, an exponential increase of the fouling number was observed.     

Taste sensing with polyacrylic acid grafted cellulose membrane

There are reports of fabrication of taste sensor by adsorbing lipids into Millipore filter paper, which improved the taste sensing efficiency of membrane remarkably. We have made an attempt to prepare taste sensor material by grafting polyacrylic acid (PAA) to cellulose. The research work covers polymer membrane preparation, morphology study, and structural characterization of the membrane and study of the taste sensing characteristics of this membrane for five different taste substances. FTIR spectroscopic analysis and SEM were done to get an idea about the structure and morphology of the PAA grafted cellulose membrane. Surface charge density of the membrane was estimated. The sensor characteristics like temporal stability, response stability, response to different taste substances, and reproducibility of sensing performance were studied using PAA grafted cellulose membrane. Sensor device prepared with this membrane has shown distinct response patterns for different taste substances in terms of membrane potential. Threshold concentrations of PAA grafted cellulose membrane for HCl, NaCl, quinine-hydrochloride (Q-HCl), sucrose and monosodium glutamate are 0.001 mM, 0.01 mM, 0.08 mM, 0.08 mM and 0.01 mM, respectively. The threshold concentrations except that in Q-HCl are below human threshold concentrations. Membranes also showed characteristic response patterns for organic acids like acetic acid, citric acid, formic acid, etc., mineral acids like HCl, H₂SO₄ and HNO₃, etc., salts, bitter substances, sweet substances and umami substances. Sensor device prepared with this membrane has excellent shelf life.