Effect of Hydraulic Retention Time on Sludge Properties,Cake Layer Structure,and Membrane Fouling in a Thermophilic Submerged Aerobic Membrane Bioreactor

Sludge properties, cake layer structure, and membrane fouling in a membrane bioreactor were studied under various hydraulic retention times (HRT). A decrease in HRT resulted in an increase in extracellular polymeric substance production in bulk sludge and changes in cake layer structure from gel layer to one or two cake layers. Particle size distribution in cake sludge changed with respect to HRT. An evolution in cake layer thickness and porosity was observed with trans-membrane pressure (TMP) jump. The change in cake layer structure might bear more responsibility for the TMP jump than the quantity of cake layer.     

Influence of Mechanical Mixing Rates on Sludge Characteristics and Membrane Fouling in MBRs

Abstract

The influence of shear intensity (G) induced by mechanical mixing on activated sludge characteristics as well as membrane fouling propensity in membrane bioreactors (MBRs) was investigated. Four MBRs were operated at different mechanical mixing conditions. The control reactor (MBR₀) was operated with aeration only supplemented by mechanical stirring at 150, 300, and 450 rpm in MBR₁₅₀, MBR₃₀₀, and MBR₄₅₀, respectively. It was found that the MBR₃₀₀ demonstrated minimum rate of membrane fouling. The fouling potential of the MBR₃₀₀ mixed liquor was lowest characterized by the specific cake resistance and the normalized capillary suction time (CST_N). Moreover, it was found that the mean particle size reduced with an increase in the shear intensity. These results reveal that membrane fouling can be significantly mitigated by appropriate shear stress on membrane fibers induced by mechanical mixing condition.     

膜生物反应器的运行和膜污染特征

研究了膜生物反应器的运行效果、膜污染特征。结果表明：膜生物反应器具有良好的污染物去除效果,在处理生活污水时COD的去除草达到90％以上,出水COD控制在80mg·L^－1以下,NH4-N的去除效果能达到95％,出水NH4-N浓度10mg·L^-1以下,膜污染的过程呈现明显的“两段式”特点,即过膜压力缓慢上升阶段和快速上升阶段。采用NaOH＋NaClO联合清洗后,膜的过膜压力迅速下降,表明膜污染以有机污染为主。     

膜生物反应器(MBR)中膜污染防治方法的研究进展

文章综述了膜生物反应器中膜污染的机理,分析了影响膜污染的主要因素,对膜污染的防治方法进行了总结与概括,并指出了今后为解决膜污染的研究工作重点。     

超市废水的膜生物反应器中污泥特性之变化

在以处理超市废水实际工程的基础上,通过对污泥性质中的胞外聚合物（EPS）、溶解性微生物产物（SMP）、污泥粒径分布（PSD）变化的分析,得出污泥性质在接种膜生物反应器（MBR）后发生了明显的变化。对SMP的荧光分析发现,芳香族蛋白质类物质的量随着运行时间的增加有减小的趋势,而色氨酸类蛋白质类物质的量则相反。同时,发现EPS中荧光峰发生了显著的位移,说明了EPS性质发生了变化;通过对污泥的红外分析,发现污泥主要以糖类、蛋白质和脂肪族类物质为主,而随着时间的变化,污泥中的代表羟基基团的峰强度发生了明显的变化,说明污泥性质发生了变化;此外,通过PSD分析发现,污泥粒径中大粒径颗粒（大于100μm）是逐渐减小的,而小粒径颗粒（10μm）逐渐增多。     

壳聚糖投加对MBR污泥混合液性质及膜污染的影响

通过试验研究了壳聚糖投加对膜一生物反应器中污泥混合液的颗粒粒径、污泥粘度、污泥脱水性能,溶解性微生物产物（SMP）及胞外聚合物（EPS）的影响。探讨了投加壳聚糖减缓膜污染的原因。结果表明投加壳聚糖提高了反应器对COD、TN、TP及NH3-N的去除效果。投加壳聚糖能够降低混合液粘度,增大污泥粒径,使污泥比阻值下降约80％。提高了污泥脱水性能,并降低了反应器中SMP的含量,从而降低了膜污染速率。     

膜生物反应器中膜污染滤饼层渗透模型的研究

在膜生物反应器中,活性污泥在膜表面沉积形成滤饼层是造成膜污染的主要因素.采用扫描电镜和自动图像分析技术研究了膜过滤滤饼层的微观结构,并以分形理论和Darcy定律为基础,推导出用于预测膜污染滤饼层渗透性能的数学模型,验证了该渗透模型的可靠性,并利用该渗透模型进行了膜生物反应器中污泥浓度对滤饼层渗透性能影响的研究.结果表明,活性污泥颗粒沉积形成的柔性滤饼层具有明显的多孔结构,并且具有很好的分形特征;膜污染滤饼层的分形维数能够真实反映滤饼层的孔隙率大小;用该渗透模型得到的渗透系数K'可以作为有效预测滤饼层渗透性能的参数;滤饼层渗透系数K'随污泥浓度的增大而递减,污泥浓度低于10000 mg·L-1时,K'的变化趋势较小,污泥浓度达到10000 mg·L-1以上时,K'急剧下降.     

丝状菌对膜生物反应器中溶解性有机物及膜污染的影响

该文以处理超市废水实际MBR工程为基础,通过对污泥膨胀过程中进出水、溶解性微生物产物(SMP)和胞外聚合物(EPS)中的溶解性有机物(DOM)特性的研究,发现SMP和进出水的DOM主要以蛋白质为主,且SMP较EPS含有更多大分子物质;同时发现SMP比EPS和进出水中含有更多50～100 kDa、100～500 kDa和...     

典型金属赋存形态对MBR膜污染影响研究进展

膜污染是膜生物反应器(MBR)进一步发展的最大障碍,污泥混合液性状是影响膜污染的关键因素.本文综述了金属离子在MBR混合液中的赋存形态,并分别对金属离子3种不同赋存形态对MBR污泥混合液及膜分离过程的影响进行了探讨.文中揭示了同价离子或异价离子共存对混合液及膜分离的影响,对共存体系中金属离子间的协同或拮抗行为也进行了讨论,并对利用高价金属离子减缓膜污染领域未来的研究趋势进行了展望.     

膜生物反应器中膜污染机理的研究

在采用膜生物反应器（MBR）处理染料废水的过程中,通过对活性污泥进行终端过滤来反映膜污染机理,着重考察了膜过滤的形式、膜通量变化和膜污染的形成。污泥的终端过滤过程严格符合沉积过滤定律;膜通量随过滤时间呈指数衰减趋势,并在几分钟内就达到相对稳定值;扫描电镜照片也证实了膜污染主要是膜面沉积层引起的。     

降低膜生物反应器中膜污染的研究

根据膜生物反应器中膜污染的几种类型,分析了膜污染形成的原因,介绍了几种描述膜污染的数学模型。从膜本身性质、料液性质到操作过程等总结了几种防止或降低膜污染的方法,提出了曝气生物滤池与膜过滤组合降低膜污染的工艺。     

膜生物反应器中的膜污染及其再生

作为21世纪最具潜力的水处理技术之一,膜生物反应器受到越来越多的重视,在污水处理与回用中有着良好的应用前景,但膜污染和膜再生技术已成为制约其发展的瓶颈.介绍了膜污染的分类和机理,并从膜的性质、混合液的性质以及操作条件等方面对形成膜污染的影响因素及膜污染的防治进行了综述,同时阐述了几种常用的膜污染再生方法.     

膜生物反应器污泥混合液对膜污染影响研究进展

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,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.本文综述了污泥混合液各组分对MBR膜分离的影响,包括溶解性微生物代谢产物(soluble microbial product,SMP)、胞外聚合物(extracellular polymeric substances,EPS)、污泥浓度(mixed liquor suspended solids,MLSS)、颗粒粒径及无机物对膜污染影响,并对该领域未来的研究方向进行了论述.     

膜生物反应器在污水处理过程中的膜污染控制

在综合国内外大量文献的基础上,阐述了MBR膜污染的类型及其发展过程,针对膜污染的影响因素,提出了防止膜污染维持MBR膜长期稳定运行的主要控制条件、方法及MBR设计的注意事项,总结了当前膜污染最佳的物理化学清洗方法,指出今后要进一步注重高性能膜材料、新型膜生物反应器和工艺条件的研究,为MBR在我国的大规模应用作准备。     

Comparison of the Cake Layer Removal Options during Determination of Cake Layer Resistance (Rc) in the Resistance-In-Series Model

The resistance-in-series (RIS) model should be used cautiously, particularly in the experimental determination of the cake layer resistance (R_c) which is determined by calculation of a series of flux data that are obtained empirically before and after removing the cake layer on the membrane surface. However, the calculated R_c values are very dependent upon the cleaning methods used for removing the cake layer. Therefore, this study investigated how the various cleaning methods influence the determination of R_c. Four different cleaning methods were used: water rinsing in a shaker, manual water rinsing, ultrasonication, and sponge scrubbing. For the hydrophilic membrane, sponge scrubbing removed the cake layer completely, whereas the other methods showed removal efficiencies ranging from 79% to 99%. For the hydrophobic membrane, none of the options achieved complete cake layer removal. In addition, sponge scrubbing was not the best option for cake removal, indicating that even a method with the potential to completely remove the cake layer on a specific membrane is not universal for every kind of membrane. Consequently, a standardized method for cake layer removal to determine cake resistance (R_c) is needed for correct interpretation of the fouling phenomena with the RIS model.     

钙离子对MBR污泥混合液及膜污染层影响研究进展

膜生物反应器(membrane bioreactor,MBR)作为一种新型的污水处理技术,以其高效、实用等特点备受人们的关注.然而,膜污染导致膜通量的下降,增加膜组件更换和清洗的频率,使其成为了影响MBR广泛应用的最大的障碍.本文首先探讨了钙离子对污泥絮体生物絮凝行为的强化机制,进而阐述了钙离子对活性污泥关键指标的影响;归纳总结了钙离子对膜污染影响的最新研究进展,最后对该领域的研究进行了展望.     

污泥龄对膜生物反应器中溶解性荧光物质特性的影响

采用三维荧光(EEM)光谱技术分析了膜-生物反应器(MBR)处理餐饮废水过程中的各种溶解性有机物(DOM),并对比研究不同污泥龄(SRT)条件下DOM的EEM光谱的迁移变化特性。结果表明各种DOM的荧光物质中,普遍存在以色氨酸为代表的蛋白质类物质,且溶解性膜污染中只有高、低激发波长色氨酸,表明蛋白质类物质是导致膜污染的重要因素。腐殖酸溯源又表明进水及出水DOM中的腐殖酸以微生物代谢产生的带有荧光基团的腐殖酸类为主。     

Performance of Membrane Bio-Reactor Equipped with Air-Sparged Side-Stream Tubular Membrane: Treatment Efficiency and Membrane Fouling

We conducted a high-load operation of a baffled bio-reactor equipped with air-sparged side-stream tubular membrane modules for treating actual municipal wastewater at two different periods (high- and low-temperature). Although nitrogen removal efficiency slightly decreased at the low-temperature period, this baffled bio-reactor showed excellent nitrogen and phosphorus removal efficiencies. We also investigated the developments of both physically reversible and irreversible fouling during operation with two-phase flow (mixed-liquor and gas) at various gas velocities and the mixed-liquor velocity was fixed at 0.50 m/s. The membrane flux was fixed at 80 L/m²/hour throughout the experiments. Regardless of the difference in temperature, the trends in the development of these two types of membrane fouling caused by the difference in gas velocity were similar. For physically reversible fouling, an optimum gas velocity, in which the development of this type of fouling was minimized, was found to be around 0.42 m/s (corresponding void fraction was 0.45). A further increase in gas velocity resulted in more reversible fouling. On the other hand, the degree of physically irreversible fouling decreased as gas velocity increased. The results obtained in this study indicated the effect of gas velocity on fouling control differs depending on the type of membrane fouling.     

改善污泥性质控制MBR膜污染的研究进展

膜生物反应器(MBR)具有高效,出水水质好的特点,在生活污水和工业废水处理中得到了应用,但膜污染是MBR广泛应用的主要障碍.介绍了污泥混合液中胞外聚合物(EPS)对膜污染的影响,详细总结了改善活性污泥混合液性质的途径,包括投加添加剂、优化运行参数和培养好氧颗粒污泥.提出了投加天然高分子混凝剂改善污泥性质的方法.