生活污水处理中胞外聚合物对膜污染的影响

采用模拟生活污水,在室温下研究了蛋白质、多糖、蛋白质/多糖浓度比(P/P)及胞外聚合物(EPS)浓度对膜污染的影响,建立了影响因素与膜压差(Dp)的二项式非线性回归方程. 结果表明,蛋白质和P/P对Dp有很大影响,其相关系数R2分别为0.5367和0.4298,原因是蛋白质很容易在膜表面上沉积且形成二次吸附,造成膜孔变小和堵塞. EPS浓度对Dp的影响较小,R2为0.1185. 多糖浓度对Dp的影响无明显的规律性是因为模拟的生活污水中的多糖浓度高和其沉积或物理吸附作用. 实验得出蛋白质是影响膜污染的最主要因素,可通过改变蛋白质与膜之间的相互作用,降低蛋白质在膜吸附层的沉积.     

曝气池活性污泥胞外聚合物对高分散悬浊液的絮凝性能研究

用蒸汽法提取曝气池活性污泥的胞外聚合物(EPS),研究了不同pH、EPS投加量、Ca2+投加量下EPS对高分散悬浊液的絮凝效果,并与不加分散剂的高岭土悬浊液进行比较.结果表明,EPS对两种高岭土悬浊液的絮凝率均随pH增加而降低,随着EPS投加量的增加,絮凝率先增大后降低;Ca2+对EPS的絮凝效果有明显的促进作用.当pH为3,EPS投加量为5 mL/L,Ca2+投加量为7 mL/L时,EPS对两种悬浊液的絮凝率分别在86.66%、95.01%以上.     

EPS对活性污泥絮凝沉降性能与表面性质的影响

采用序批式生物反应器（SBR）处理模拟废水,在葡萄糖作为碳源的条件下,调整进水碳源浓度改变系统内EPS含量,考察EPS的变化对活性污泥絮凝沉降性能及其表面性质的影响。结果表明,出水悬浮固体浓度（ESS）愈小,污泥絮体重絮能力（FA）越大,絮凝效果愈好。随着EPS的增加,ESS和污泥容积指数（SVI）升高,FA和ZSV降低,导致活性污泥絮凝性能和沉降性能下降。EPS与ESS呈正相关,EPS与FA呈负相关（R2分别为0.9916和-0.9941）,EPS与SVI呈正相关性,EPS与区域沉降速率（ZSV）呈负相关性（R2分别为0.9451和-0.9805）。同时,EPS的增加对污泥表面性质产生重要影响,EPS的增加导致污泥表面Zeta电位下降,污泥相对疏水性RH逐渐降低。Zeta电位的下降和RH的降低直接引起SVI和ESS增大,导致污泥絮凝沉降性能下降。EPS总量与Zeta电位和RH的相关性系数R2分别为-0.99、-0.9979。     

胞外聚合物在污水处理过程中的功能及其控制策略

对胞外聚合物(EPS)的形成机理、组成、分类进行了总结,并分析了其组分性质及其对EPS性能的影响。探讨了EPS在生物膜和颗粒污泥形成过程中的作用及对污水处理的影响,论述了影响污水生物处理过程中EPS产生和组成的因素,并对控制EPS产生和组成的方法和措施进行了阐述。     

胞外聚合物对膜污染的影响及对策

膜生物反应器(MBR)中膜污染问题直接影响了工艺的稳定性和经济性。通过分析膜污染机理发现,胞外聚合物(EPS)在膜污染中起重要作用。从EPS的性质、组成及影响因素等方面进行了归纳总结,并对膜污染控制提出了相应的对策。     

高价金属离子对MBR中胞外聚合物影响的研究进展

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主要瓶颈,可导致出水通量下降、跨膜压差增加、洗膜及换膜频繁等.众多研究证实向MBR中投加高价金属离子可有效减缓膜污染,本文首先简述胞外聚合物(extracellularpolymeric substances,EPS)和高价金属离子与污泥混合液间的作用机理,其次,总结常用的三种高价金属离子(钙、铁、铝离子)在污泥混合液中分布规律及其影响.最后对高价金属离子在未来的应用进行展望.     

污泥中胞外聚合物(EPS)的研究进展

本文介绍了污水处理厂剩余污泥中胞外聚合物（Extracellular Polymeric Substances,EPS）的产生和组成（多糖、蛋白质、DNA、腐殖酸等）;通过对影响EPS的因素研究发现：基质类型、溶解氧（DO）、污泥停留时间（SRT）和有机负荷率是最主要的影响因素;胞外聚合物在污泥处理系统中对污泥的絮凝性能、沉降性能、脱水性能及重金属吸附性能的影响,及其本身的生物降解性。胞外聚合物在废水生物处理中发挥着重要作用。     

金属离子对膜生物反应器混合液可滤性影响研究进展

膜生物反应器(MBR)作为一种高效的污水处理及回用工艺,近年来备受关注,然而MBR的膜污染问题严重制约了该工艺进一步快速的商业化推广。本文综述了金属离子对MBR污泥混合液可滤性的作用,并探讨了混合液中胞外聚合物(EPS)和溶解性微生物代谢产物(SMP)对膜污染影响。为说明高价金属离子对混合液可滤性的调控作用,文中通过DLVO、DCB及箱蛋理论深入探讨了金属离子对生物絮凝影响的机理。最后,对该领域未来的研究方向进行了论述。     

运行工况对膜生物反应器内污泥特性的影响

探讨了膜生物反应器的运行工况对MBR内胞外聚合物(EPs)及污泥特性的影响,试验结果表明:污泥负荷№增加,污泥EPs降低,Zeta电位值降低.沉降性能变好,活性增加;曝气量增加,污泥EPs降低,Zeta电位值降低,沉降性能变好,活性先增加后降低;pH值由酸性变为碱性,污泥EPs增加,Zeta电位值增加.沉降性能先变好后...     

膜生物反应器连续发酵生产胞外灵芝多糖

产物灵芝多糖在间歇深层发酵稳定期存在浓度下降现象，采用膜生物反应器系统能够及时分离产物，控制产物的积累，有效防止灵芝多糖的消耗，而灵芝菌丝体在反应器中不断循环，浓度得到进一步提高，并不断分泌灵芝胞外多糖，可延长产多糖时间，从而提高了胞外多糖的总产量，研究了不同稀释率0－0．2hr^-1下连续发酵的多糖生成和菌丝体生长状况；连续发酵时发酵液中灵芝多糖的浓度比间歇发酵要低，并随稀释率的增大而下降，菌丝体浓度则随稀释率的增大而增大，总的菌丝体干重可比间歇发酵增加20％以上，多糖总产量可达到间歇发酵的5倍以上，连续发酵也有利于灵芝多糖与菌丝体的分离，结果表明利用膜生物反应器进行液体连续发酵是生产和分离胞外灵芝多糖的一条有效途径，并可为其它真菌胞外多糖的深层发酵生产提供借鉴。     

Extracellular Polymeric Substances in Fouling Layer

Abstract

Membrane biofouling via microbial products limits the feasibility of utilizing membrane bioreactor (MBR) for treating wastewater. Fouling layer would be built up when activated sludge was filtered with a mixed cellulose ester membrane. This study probed the three‐dimensional distributions of protein, α‐polysaccharide, and β‐polysaccharide in fouling layer using fluorescently labeled lectins and fluorescein isothiocyanate (FITC) as staining agents in combination with confocal laser scanning microscopy (CLSM). These extracellular polymeric substances (EPS) distributed heterogeneously in the fouling layer, with α‐polysaccharide being concentrated close to the membrane surface. The flow pattern yielded in the fouling layer determines the filtration resistance of biofouling.     

胞外聚合物生物除磷研究进展

胞外聚合物是活性污泥絮体的主要成分,在污水处理中发挥着重要作用。介绍了胞外聚合物的组成结构、提取和分析测定方法,在此基础上综述了胞外聚合物在生物除磷中的研究现状,指出了该领域存在的问题,并对胞外聚合物生物除磷技术进行了展望。     

Biofilm Structure and Extracellular Polymeric Substances in Low and High Dissolved Oxygen Membrane Bioreactors

Abstract

This paper discusses the effect of dissolved oxygen (DO) on the biofilm structure in membrane bioreactor (MBR) and their consequence on membrane permeability and EPS. Two MBRs under high DO (6.0 mg/L, HDO) and low DO (<0.1 mg/L, LDO) were operated in parallel under same hydrodynamic conditions. The microbiological aspects in MBR systems were explored through a series of analysis techniques including PCR‐DGGE, gel filtration chromatography (GFC), confocal laser scanning microscope (CLSM), and image analysis.

The rate of membrane fouling for the LDO MBR was 5 times faster than that for the HDO MBR. The microbial communities between HDO and LDO MBR were quite different, which is likely to be the reason for different structures and permeabilities of the biofilms. The specific biofilm resistance in HDO MBR was lower to that in LDO MBR. This is attributed to relatively lower porosity and higher amount of EPS for the biofilm in LDO MBR. The distributions of cell and EPS were not uniform in the biofilms in both HDO and LDO MBR. The biofilm in LDO MBR contained larger amount of EPS than that in HDO MBR. The ratio of protein to polysaccharide was also higher for biofilm in HDO MBR than in LDO MBR.     

Extracellular Polymeric Substances and Biocorrosion/Biofouling: Recent Advances and Future Perspectives

Microbial cells secrete extracellular polymeric substances (EPS) to adhere to material surfaces, if they get in contact with solid materials such as metals. After phase equilibrium, microorganisms can adhere firmly to the metal surfaces causing metal dissolution and corrosion. Attachment and adhesion of microorganisms via EPS increase the possibility and the rate of metal corrosion. Many components of EPS are electrochemical and redox active, making them closely related to metal corrosion. Functional groups in EPS have specific adsorption ability, causing them to play a key role in biocorrosion. This review emphasizes EPS properties related to metal corrosion and protection and the underlying microbially influenced corrosion (MIC) mechanisms. Future perspectives regarding a comprehensive study of MIC mechanisms and green methodologies for corrosion protection are provided.     

Effect of magnetic field on surface properties of Bacillus cereus CrA and its Extracellular Polymeric Substances (EPS)

The effect of magnetic field on surface properties of Bacillus cereus CrA and its EPS was studied by zeta potential and FT-IR spectrum. The weak magnetic fields of 6.0–10.0 mT promoted the predominant strain B. cereus CrA to form EPS. The weak magnetic field of 2.4–10.0 mT could improve the bio-adsorption efficiency of anions by decreasing the negative charge of the intact strain, while the magnetic field of 17.4 mT could increase the negative charge of the strain’s EPS by 20% and be responsible for the bio-adsorption of cations. Magnetic field could affect the band intensity and the slight shifting of peaks and the fluctuation of the bacterial absorption capability depended on the magnetic density. The magnetic field energy could affect the hydroxyl group and carboxyl group by forming hydrogen bonding, which were responsible for the adsorption ability of the strain and its EPS.     

丙烯腈聚合废水的絮凝处理

采用絮凝方法,利用明矾、氯化铁和硫酸亚铁三种絮凝剂对丙烯腈聚合废水的处理进行了研究,找出最佳pH和絮凝剂用量。结果表明,明矾、氯化铁和硫酸亚铁的最佳pH分别为8．5、8．5和9,在各自的最佳pH条件下,三种絮凝剂的最佳用量分别为200mg/l、250mg/l和400mg/l。     

Effect of Pectinase Immobilization in a Polymeric Membrane on Ultrafiltration of Fluid Foods

The aim of this research was to obtain an enzymatic membrane reactor for use to clarify a model system and apple juice with a 12% soluble solid content and 1 mg/mL of pectin by water-soluble pectinolytic enzymes which were immobilized on polysulfone membranes. These membranes were synthesized in the laboratory by immersion precipitation (phase inversion) from polysulfone with and without active carbon. To ensure the cut-off separation of the membrane in the ultrafiltration process a commercial flat membrane with an 8-kDa molecular weight cut-off was used. The influence of different parameters (viscosity, density, reducing sugars, color, pH, and presence of pectin) on the initial sample and the volumetric permeate flux was also evaluated. The obtained membranes were characterized physically using a scanning electron microscopy SEM and analyses were performed with IFME® software.

The results indicated that immobilization of the enzyme in the membrane allowed an interaction between the recirculating sample and the membrane, the one obtained with activated carbon and immobilized enzymes showed higher degradation of pectin, improving the performance of the volumetric permeate flux.     

碳纳米管对活性污泥胞外聚合物的吸附特性研究

以单壁碳纳米管(SWNTs)为吸附剂,系统地研究了其对活性污泥胞外聚合物(EPS)的吸附特性.结果表明,SWNTs能够快速吸附EPS,当吸附剂投加量为0.9 g/L时,吸附在20 min即可达到平衡,吸附动力学符合准二级动力学模型.吸附等温线能较好地用Langmuir 吸附等温模型来描述,最大单分子吸附量为123.577 mg/g.pH值对吸附有较大影响,最佳吸附pH范围为5～7.