MBR、MCR处理微污染水的膜污染比较

膜污染是影响膜反应器稳定运行的重要原因之一，为此考察了膜生物反应器(MBR)和膜混凝反应器(MCR)处理微污染地表水时的运行状况，并对膜比通量的变化进行了比较，发现MBR的膜污染情况比MCR的严重。MCR和MBR的膜组件经物理、化学清洗后膜比通量分别恢复至新膜比通量的99．7％和76．9％，物理清洗对此的贡献较大。经分析发现，MCR中无机污染占优势，主要污染元素是Fe；MBR中微生物和有机物是膜污染的主要组成，而无机污染物则主要是铁盐和磷酸盐。     

延缓膜生物反应器中膜污染的措施探讨

膜生物反应器是膜分离技术和污水生物处理技术有机结合的一种污水处理工艺，与传统污水处理工艺相比具有很多优点，但膜污染限制了该工艺的广泛应用。介绍了膜污染的定义，系统论述了膜污染的研究进展，着重从改良膜的性质、改善污泥混合液的特性和优化膜分离操作条件等三个方面介绍了国内外有效延缓膜污染的技术措施。     

纳滤膜污染形成与控制研究进展

纳滤技术以其操作压力低、对二价离子截留率高且能保留水中有益微量元素等特点广泛应用于水处理领域的各个方面,但是膜污染一直是影响纳滤膜应用和发展的瓶颈问题。本文总结了纳滤膜污染的类型、形成机理及污染特性,讨论了膜污染形成的影响因素及预防控制方法措施,提出了今后膜污染机制及控制的研究方向,以促进纳滤技术在饮用水处理行业的推广应用。     

超滤膜的污染控制研究进展

以超滤技术为核心的组合工艺作为微污染水源水处理的一项新技术,引起了人们越来越多的关注,成为给水处理领域研究的热点,也为农村和小城镇水厂提供了很好的处理工艺,但膜污染一直是超滤技术在实际工程中推广应用所面临的一大障碍.总结了近年来超滤膜污染控制方面的新进展,包括膜污染的成因及机理、膜污染防治以及膜清洗等,并提出了今后超滤膜污染研究的重点和方向.     

膜污染和膜材料的最新研究进展

介绍了近两年来国际上膜污染和膜材料领域的最新研究进展。目前,研究学者对膜污染机理进行了深入研究,建立了新的膜污染表征和控制方法,并通过膜材料的改性来逐步解决膜污染问题。     

清洁生产思想在膜污染控制中的运用

将现代清洁生产的思想应用到膜污染控制之中，并据此建立了全过程控制方法，即源头控制、过程控制以及末端治理相结合的控制方法，以求最大限度地减缓膜污染，从而加快MBR在实际工程中的应用。     

超滤膜污染EFM清洗效果研究及污染物成分分析

以长期运行后的受污染超滤膜为研究对象,考察了采用不同维护性化学清洗（EFM）方式对受污染膜组件的清洗效果,并采用扫描电镜（SEM）和能谱仪等对造成膜污染的污染物成分进行了分析.结果表明,EFM清洗的最佳方式为以柠檬酸清洗为主,间歇采用NaCLO清洗,最佳投药量均为200 mag/L;结合SEM和能谱仪的检测结果可以得出,含有Fe、Si等元素的无机污染物是造成膜污染的主要污染成分,而EFM清洗前有机物在膜表面的沉积相对较少.     

微滤膜处理微污染原水研究

采用0．1μm的微滤膜处理微污染原水，出水浊度＜1NTU，对高锰酸盐指数（OC）的去除率为20％左右，运行稳定后对UV24去除率＞40％。通过考察膜过滤阻力在膜油－停周期内的变化来选择充分的曝气时间。在连续运行中发现，膜过滤性能由于膜的污染而先有一快速降低段，之后随时间缓慢下降。通过对膜的清洗的长期运行试验发现，曝气清洗不能完全清除膜污染，而用次氯酸钠和盐酸清洗则较为有效。     

膜污染及其控制

减轻膜污染,延长膜的使用寿命,提高膜通量,具有重要指导意义。引起膜通量降低主要有两方面的原因:浓差极化和膜污染。多年来,国内外在膜污染的理论研究和应用实践的基础上,积累了不少行之有效的经验和方法,本文对这些方法进行了总结、概括。     

MBR处理印染废水的膜污染及清洗研究

膜生物反应器（MBR）是一种新型反应器，处理印染废水时除污效果很显著，但长时间的运行会造成膜的严重污染，为此对A／OMBR（厌氧—膜生物反应器）处理印染废水时的膜污染情况和清洗效果做了研究。结果表明，膜污染主要是由膜表面凝胶层造成的；化学清洗的效果优于物理清洗（化学清洗能恢复膜通量约90％以上，而物理清洗仅能恢复膜通量约70％）；NaOH的清洗效果优于NaOCl。     

UF膜组件的有机污染及清洗

近年来,超滤（UF）膜组件的污染问题主要集中在有机物污染的范围。利用几种化学药剂对聚砜超滤膜有机污染造成的堵塞的清洗方式进行了试验研究,研究了UF件的有机污染行为及膜组件污染物的去除。实验证明NaClO,H2O2和NaOH对于UF膜的有机污染去除都有一定的效果,其中H2O2的去除效果最好。控制原水的PH值有利于减轻膜污染。同时,以NaOH／NaClO及NaOH／H2O2水溶液相结合的方式对于膜的蛋白质污染的去除也有很好的效果,能够使超滤膜的渗透水通量恢复到初始值。同时还对UF膜的有机污染形成基理进行了分析。     

Fouling Potential Determination of a UASB Effluent Using Different Assessment Methods

The fouling potential of a pilot-scale UASB effluent was determined using different assessment methods (SDI and MFI tests and a mathematical analysis based on a saturation curve model). The UASB reactor was operated at HRT of 4, 8 and 12 h. Although the three methods employed were adequate as a predictive tool for UF membrane fouling, the saturation curve analysis revealed a clearer relationship between the fouling potential of the UASB effluent and the HRT applied. It was found that operating a UASB reactor under short HRT, such as 4 h, could increase membrane fouling in a post-treatment UF module.     

Irreversible membrane fouling during ultrafiltration of surface water

For more efficient use of membranes, the control of irreversible membrane fouling, which can be defined as fouling requiring chemical reagents to be mitigated, is of importance. In this study, irreversible fouling caused by constituents in surface water was investigated, based on a long-term pilot scale study. The membrane employed was a low-pressure hydrophobic ultrafiltration (UF) membrane made of polysulfone and having a molecular weight cutoff of 750,000 Da. Various chemical reagents were examined to overcome the irreversible fouling that had developed through 5 months of continuous filtration. Among the tested cleaning reagents, alkaline (NaOH) and oxidizing reagent (NaClO) showed good performance in the restoration of membrane permeability, which implied that organic matter played an important role in the development of the irreversible fouling in this study. Chemical analysis, adsorptive fractionation methods, fluorescence excitation-emission matrix (EEM) and Fourie-transformed infra-red (FTIR) spectra analysis were applied to elucidate which fraction of organic matter caused the irreversible fouling. All of the analysis indicated that polysaccharide-like organic matter was responsible for the evolution of the irreversible fouling. In addition to organic matter, presumably iron and manganese also contributed to the irreversible fouling to some extent.     

Analysis of fouling mechanisms in anaerobic membrane bioreactors

In this paper, we investigate the fouling mechanisms responsible for MF and UF membrane flux decline in Anaerobic Membrane Bioreactors (AnMBR). We have used the fouling mechanism models proposed by Hermia (1982), namely pore constriction, cake formation, complete blocking and intermediate blocking. Based on an optimization approach and using experimental data extracted from the literature, we propose a systematic procedure for identifying the most likely fouling mechanism in play. Short-term as well as long-term experiments are considered and discussed. It was found that short-term experiments are usually characterized by two fouling phases during which the same fouling mechanism or two different mechanisms affect the process. In contrast, in long-term experiments involving cleaning cycles, membrane fouling appears to be better ascribed to one phase only.The impact of abiotic parameters on membrane fouling mechanisms is reviewed and discussed in the light of these results. Finally, it is shown that the mechanism most responsible for membrane fouling in an AnMBR is cake formation. This main result will be useful for the future development of simple integrated models for optimization and control.     

中空纤维超滤膜处理滦河水中试研究

采用混凝-超滤工艺对滦河原水进行了中试研究,重点考察了PVC中空纤维超滤膜对不同水质期的滦河水中污染物的去除情况。结果表明：水温降低使膜性能下降。膜污染较严重;在高藻期进行预氯化有助于减缓膜污染;针对不同的水质期要采用不同的预处理方法。在低温期适当增加铁盐投量,高藻期进行预氯化都有助于系统稳定运行;膜出水在3个水质期（低温、常温、高藻期）均很稳定,与常规工艺相比,膜工艺具有一定的优越性,在去除浊度和颗粒物方面尤为突出。     

Impact of polymer flocculants on coagulation-microfiltration of surface water

Organic polymers are widely used as flocculants in pretreatment for microfiltration. However, their impact on microfiltration system performance was not well understood. In this study, the effects of three types of polymer flocculants on microfiltration permeate water quality and membrane fouling were evaluated using a hollow fiber membrane under two different operation modes, coagulation/flocculation-sedimentation-microfiltration (CFSM) and coagulation/flocculation-microfiltration (CFM). Interestingly, the effect of polymers on membrane fouling did not appear to reflect their impact on dissolved organic matter content or floc particle properties in the membrane feed water. The addition of polymer flocculants resulted in floc particles of larger size and smaller fractal dimension and slightly enhanced the removal of dissolved organic matter, both of which were expected to reduce membrane fouling. However, it significantly aggravated membrane fouling in all cases except when the positively charged poly(diallyldimethylammonium) chloride was used in the CFSM process. In particular, all polymers greatly increased hydraulically irreversible fouling in the CFM mode. The increased fouling in the CFSM mode is attributed to the residual polymer, while that in the CFM mode is attributed to the enhanced irreversible floc particle attachment on the membrane surface. Considering the potential severe membrane fouling and the small improvement in treated water quality when polymers are used, the application of polymers in microfiltration pretreatment needs to be carefully evaluated.     

Fouling of microfiltration membranes by organic polymer coagulants and flocculants: Controlling factors and mechanisms

Organic polymers are commonly used as coagulants or flocculants in pretreatment for microfiltration (MF). These high molecular weight compounds are potential membrane foulants when carried over to the MF filters. This study examined fouling of three MF membranes of different materials by three commonly used water treatment polymers: poly(diallyldimethylammonium) chloride (pDADMAC), polyacrylamide (PAM), and poly(acrylic acid-co-acrylamide (PACA) with a wide range of molecular weights. The effects of polymer molecular characteristics, membrane surface properties, solution condition and polymer concentration on membrane fouling were investigated. Results showed severe fouling of microfiltration membranes at very low polymer concentrations, suggesting that residual polymers carried over from the coagulation/flocculation basin can contribute significantly to membrane fouling. The interactions between polymers and membranes depended strongly on the molecular size and charge of the polymer. High molecular weight, positively charged polymers caused the greatest fouling. Blockage of membrane pore openings was identified as the main fouling mechanism with no detectable internal fouling in spite of the small molecular size of the polymers relative to the membrane pore size. Solution conditions (e.g., pH and calcium concentration) that led to larger polymer molecular or aggregate sizes resulted in greater fouling.     

膜生物反应器中的膜污染研究综述

介绍了膜污染机理,阐述了膜污染的影响因素及对于膜生物反应器中膜污染的研究近况,并提出相应的膜污染控制措施,从而为今后对膜污染的研究工作指明方向和提供宏观上的指导,以期推广该工艺在实际工程中的应用。     

Changes in characteristics of soluble microbial products in membrane bioreactors associated with different solid retention times: Relation to membrane fouling

A membrane bioreactor (MBR) is a promising wastewater treatment technology, but there is a need for efficient control of membrane fouling, which increases operational and maintenance costs. Soluble microbial products (SMP) have been reported to act as major foulants in the operation of MBRs used for wastewater treatment. In this study, SMP in MBRs operated with different sludge retention times (SRTs) were investigated by means of various analytical techniques and their relations to the evolution of membrane fouling were considered. Bench-scale filtration experiments were carried out in a laboratory with synthetic wastewater to eliminate fluctuations that would occur with the use of real wastewater and that would lead to fluctuations in compositions of SMP. Three identical submerged MBRs were operated for about 50 days under the same conditions except for SRT (17, 51 and 102 days). Accumulation of SMP in the MBRs estimated by conventional analytical methods (i.e., the phenol-sulfuric acid method and the Lowry method) was significant in the cases of short SRTs. However, the degrees of membrane fouling in the MBRs were not directly related to the concentrations of SMP in the reactors estimated by the conventional analytical methods. Non-conventional analytical methods such as excitation-emission matrix (EEM) fluorescence spectroscopy revealed that characteristics of SMP in the three reactors considerably differed depending on SRT. Foulants were extracted from the fouled membranes at the end of the operation and were compared with SMP in each MBR. It was clearly shown that characteristics of the foulants were different depending on SRT, and similarities between SMP and the extracted foulants were recognized in each MBR on the basis of results of EEM measurements. However, such similarities were not found on the basis of results obtained by using the conventional methods for analysis of SMP. The results of this study suggest that the use of conventional methods for analysis of SMP is not appropriate for investigation of membrane fouling in MBRs.     

超滤预处理技术在膜污染防止中的应用

作为一种具有发展前景的饮用水净化工艺,超滤膜技术日益得到广泛应用。但是膜污染一直是困扰其发展的主要因素。将传统的处理技术与超滤膜相结合,通过预处理的方式在提高水质的同时可以防止膜污染的生成。本文主要讨论了混凝、吸附、预氧化和其他预处理方法及其组合方法在水处理中应用和对膜污染的抑制作用。未来研究方向应在深入讨论膜污染机理的基础上,针对不同情况进行分析。