膜分离技术在食品废水处理和生产中的应用

乳制品废水在酸沉和离心预处理后,通过微滤、超滤、纳滤、反渗透截留废水中的微生物、蛋白质和乳糖等物质,即可达到回用或排放要求。大豆乳清废水经沉淀和离心处理后,采用超滤回收废水中的蛋白质,再用纳滤脱盐、回收低聚糖,滤液过反渗透膜即可达到回用或排放要求。味精废水采用超滤和反渗透双膜法,或用陶瓷膜和电渗析结合处理后,得到的滤液既可再次用于工艺生产。在生产酱油和食醋时,采用微滤、纳滤、陶瓷膜、电渗析处理,不仅能够改善酱油和食醋的风味,还能延长其储藏周期。最后,对膜分离技术治理食品工业废水的应用前景进行了展望。     

膜分离技术的后起之秀—纳滤

纳滤是介于超滤与反渗透之间的一种膜分离技术,其截留分子量在200～1000的范围内,孔径为几纳米,因此称为纳滤。由于纳滤膜表面有一层均匀的超薄脱盐层,它比反渗透膜要疏松得多,且其操作压力比反渗透低,因此纳滤又称为疏松型反渗透或低压反渗透。基于纳滤分离技术一系列优越的特性,其在制药、生物化工、食品工业等诸多领域显示出广阔的应用前景。以往对分子量在几百的不同分子的分离,采用反渗透和超滤都难以实施,而纳滤就可从蔗糖(分子量342)与葡萄糖(分子量180)的混合液中分离出葡萄糖。纳滤的另一个特点是它能截留小分子有机物并可同时透析…     

膜分离技术及其在果汁加工中的应用

介绍了应用于果汁加工中的膜分离过程(微滤、超滤、纳滤、反渗透、电渗析、膜蒸馏)及其分离性能。由渗透通量和截留率表征,在果汁加工中,膜分离技术可用于果汁的澄清、浓缩、脱气、脱苦、脱酸、脱色等。     

膜分离在蛋白质分离纯化中的应用

以压力差为推动力膜分离过程（过滤，超滤，纳滤，反渗透）的分离性能由透过通量和截留率表征，其操作模式分浓缩和渗滤两种。膜分离技术用于分离，纯化，回收和浓缩蛋白质，如乳清蛋白，血清白蛋白，蛋清蛋白，西蒙德木蛋白，重组白细胞介素－2包涵体以及二元蛋白质混合物等。     

反渗透处理对废水质量的影响

从70年代初期，膜分离技术就在很多领域内成功地应用，微滤、超滤、反渗透都属于膜分离过程。微波适用于分离0．1－10μm范围内的粒子，超滤适用于分离0．01－0．1μm范围内的粒子，而反渗透可以0．001μm或小于0．001μm的粒子。在分子量截留限值方面：微滤截留分子量大于1000000，超滤截留分子量500－500000，反渗透截留分子量小于500。     

生物工程中的膜技术应用研究新进展

介绍了超滤、纳滤、反渗透、离子交换膜分离、渗透汽化、气体分离、膜蒸馏、亲合膜分离、膜生物反应器等膜技术在生物工程中应用研究新进展。     

食品添加剂工业中的膜技术进展

本文介绍了超滤、纳滤、反渗透、离子交换膜分离、渗透汽化、气体分离、膜蒸馏、亲合膜分离、膜生物反应器等膜技术在食品添加剂工业中应用研究新进展.     

膜分离技术在菠萝汁加工中的应用研究

采用膜分离技术,包括超滤、反渗透、纳滤,分别对菠萝汁进行处理,研究了各种膜的运行时间与操作压力对膜分离效果的影响,并对膜分离效果进行评价.结果表明,超滤处理菠萝汁的最佳操作压力为0.12MPa,反渗透与纳滤处理菠萝汁的最佳操作压力均为0.50MPa.卷式膜的抗污染能力优于中空纤维式膜,碱液清洗后卷式膜的膜通量恢复率达到了96%以上;超滤膜分离可基本保留菠萝汁中的营养成分,并有效去除果汁中的微小颗粒物质.起到了澄清作用;反渗透与纳滤处理菠萝汁,能够对果汁起到一定的浓缩作用.     

纳滤技术及其在功能性低聚糖分离纯化中的应用

纳滤是介于反渗透和超滤之间的一种较新膜技术,本文阐述了纳滤膜的种类及膜分离装置,纳滤的特性及机理,并综述了其在功能性低聚糖分离纯化中的应用。     

纳滤技术及其在功能性低聚糖分离纯化中的应用

纳滤是介于反渗透和超滤之间的一种较新膜技术，本文阐述了纳滤膜的种类及膜分离装置，纳滤的特性及机理，并综述了其在功能性低聚糖分离纯化中的应用。     

Recovery and purification of potato proteins from potato starch wastewater by hollow fiber separation membrane integrated process

Potato starch wastewater contains high-concentration potato proteins which have great potential in the fields of food and health care. Most researches on potato protein recovery by membrane separation technique are focused on flat sheet or tubular ultrafiltration (UF) and reverse osmosis (RO) membranes and lack the further protein purification and the in-depth discussions on the fouling behavior. In this laboratory-scale study, potato proteins were recovered and purified from the simulated potato starch wastewater by the self-made hollow fiber (HF) UF and nanofiltration (NF) separation membrane integrated process. 85.62% potato proteins with high molecular weight in the potato starch wastewater could be retained by UF membrane and 92.1% potato proteins with low molecular weight were rejected by NF membrane. The concentrated solution after UF and NF filtration was desalinated and purified by diluting the solution eight times and filtering the diluted solution with UF membrane. Both types of HF membranes, UF and NF, suffered the inevitable membrane fouling. After the traditional physical washing and chemical cleaning, water flux of UF and NF membranes can be effectively recovered. The corresponding recovery rates of UF and NF membranes can reach 93.5% and 84.7%, respectively. The hollow fiber UF-NF separation membrane integrated process was proved to be a promising technique of high-purity potato protein recovery from potato starch wastewater.     

膜分离技术处理茶叶废水的研究

从茶叶中提取茶多酚后所产生的废水中有机物含量高,难以直接用生化法处理。首先采用超滤技术对茶叶废水进行浓缩,以除去胶体等大分子物质,滤液再经反渗透处理可除去小分子溶质。分别考察了操作时间以及膜污染清洗对超滤膜和反渗透膜水通量的影响,并对各阶段浓缩液及滤液的理化性质进行了比较分析。结果表明,经超滤及反渗透处理后,废水的COD由54642.32mg/L降到了96.80mg/L,COD去除率为99.82%,处理后的水质可直接排放或回收利用到茶叶提取工序,浓缩液可分别制成茶多糖及茶饮料产品,变废为宝,综合利用。     

Role of soluble microbial products (SMP) in membrane fouling and flux decline

Soluble microbial products (SMP), a significant component of effluent organic matter (EfOM), play an important role in membrane fouling and flux decline in wastewater reclamation/reuse applications. The SMP compounds of a microbial origin are derived during biological processes of wastewater treatment. They exhibit the characteristics of hydrophilic organic colloids and macromolecules. These high molecular weight compounds play an important role in creating high resistance of the membrane, leading to a reduction of permeate flux. The SMP fouling of RO, NF, and tight UF membranes is associated with formation of a cake/gel layer due to size (steric) exclusion. FTIR spectra of SMP- and EfOM-fouled membranes exhibited foulants' composition, consisting of polysaccharides, proteins, and/or aminosugar-like compounds. This finding reveals the important role of the SMP components as factors in membrane fouling and flux decline associated with EfOM source waters. Solids retention time (SRT) affects the characteristics and amounts of SMP, however, SRT did not affect flux decline trends of RO and NF membranes.     

Influence of flocculation and adsorption as pretreatment on the fouling of ultrafiltration and nanofiltration membranes: application with biologically treated sewage effluent

Membrane fouling is a critical limitation on the application of membranes to wastewater reuse. This work aims to understand the fouling phenomenon which occurs in ultrafiltration (UF; 17500 molecular weight cutoff (MWCO)) and nanofiltration (NF; 250 MWCO) membranes, with and without pretreatment. For this purpose, the molecular weight (MW) distribution of the organics has been used as a parameter to characterize the influent, the permeate, and the foulant on the membrane surface. The variation of foulant concentration on the membrane due to pretreatment of the influent by flocculation and/or adsorption was investigated in detail. With the UF membrane, the peak of the MW distribution of organics in the permeate depended on the pretreatment; for example, the weight-averaged MW (Mw) of 675 without pretreatment shifted down to 314 with pretreatment. In the case of the NF membrane, the Mw of organics in the permeate was 478 (without pretreatment) and 310 (with flocculation followed by adsorption). The Mw of the organics in the foulant on the membrane surface was 513 (UF) and 192 (NF) without pretreatment and 351 (UF) and 183 (NF) after pretreatment with flocculation followed by adsorption, respectively. Without the pretreatment, the foulant concentration was higher on both membranes. The difference was more significant on the UF membrane than on the NF membrane. For both membranes, the flocculation-and-then-adsorption pretreatment proved very effective.     

食品工业废水的膜法处理与回用技术

食品工业中产生的废水量大,水质恶劣,对环境的污染严重。味精和酒精生产中的废水以及大豆、谷物、果蔬、肉类、牛乳和饮料加工中的废水,是食品工业废水的主要来源。文中在对大量文献资料的调研以及总结膜技术处理废水工程经验的基础上,重点讨论了用微孔过滤(MF)、超滤(UF)、纳滤(NF)、反渗透(RO)、电渗析(ED)、渗透汽化(PV)、膜生物反应器(MBR)技术处理食品工业废水的现状,概要分析了膜技术处理与回用食品工业废水的工艺参数、工程运行及其产生的社会效益和经济效益。     

膜技术分离纯化金银花绿原酸提取液工艺研究

研究膜技术分离纯化绿原酸提取液的过程。以金银花为原料,以平均通量、膜截留率、绿原酸透过率为指标,比较3 种微滤膜MF1、MF2 和MF3,4 种超滤膜UF1、UF2、UF3 和UF4,及两种反渗透膜RO1 和RO2 对绿原酸提取液的过滤特性,并研究浓缩液的洗滤对绿原酸截留率的影响。结果表明：MF1、UF1 和RO2膜的过滤性能明显优于其他同类型膜,使用MF1-UF1-RO2 膜组合处理效果最佳,其绿原酸回收率可达67.75%,产品纯度可达13.21% 以上;同时,洗滤可进一步提高处理效果,经间歇洗滤后,MF1 膜的绿原酸截留率可由9.54% 降低到1.17%,UF2 膜的绿原酸截留率可由32.36% 降低到20.11%。     

Purification and Concentration of Betalaines by Ultrafiltration and Reverse Osmosis

Beet juices prepared by solid-liquid extractions were processed by ultrafiltration (UF) and reverse osmosis (RO) to 30°Brix at 20°C. De Danske Sukkerfabrikker (DDS) UF/RO Lab Module-20 plate-and-frame system was used having a 0.72-m² effective membrane area and pressures from 50-40 bar. After prefiltering, pectinase treated juices were sequentially processed through 20,000 and 6,000 (UF) molecular weight (MW) cut-off membranes. The UF purified products were then concentrated by RO processes on several types of cellulose acetate (CA) membranes, one with a 500 MW cut-off and 70% NaCl permeability provided colorants that were separated from a majority of soluble solids. Addition of invertase to pectinase-treated juices decreased flux but yielded a three-fold increase in betalaine concentration on a dry weight basis. Betalaine concentration by UF and RO processes also halved nitrate level and greatly reduced flavor.     

Effect of flux (transmembrane pressure) and membrane properties on fouling and rejection of reverse osmosis and nanofiltration membranes treating perfluorooctane sulfonate containing wastewater

Perfluorooctane sulfonate (PFOS) is an emergent contaminant of substantial environmental concerns. In this study, reverse osmosis (RO) and nanofiltration (NF) membranes were used to remove this toxic and persistent compound from PFOS-containing wastewater. Five RO membranes and three NF membranes were tested at a feed concentration of 10 ppm PFOS over 4 days, and the PFOS rejection and permeate flux performances were systematically investigated. PFOS rejection was well correlated to sodium chloride rejection. The rejection efficiencies for the RO membranes were > 99%, and those for the NF membranes ranged from 90-99%. Improvement in PFOS rejection, together with mild flux reduction (< 16%), was observed at longer filtration time. Such shifts in rejection and flux performance were probably due to the increased PFOS accumulation at longer duration, as shown by X-ray photoelectron spectroscopy and liquid chromatograph and tandem mass spectrometry results. A fraction of PFOS molecules might be entrapped in the polyamide layer of the composite membranes, which hindered the further passage of both water and other PFOS molecules. In a similar fashion, PFOS rejection and fouling were enhanced for greater initial flux and/or applied pressure, where PFOS accumulation was promoted probably due to increased hydrodynamic permeate drag. Flux reduction was also shown to correlate to membrane roughness, with the rougher membranes tend to experience more flux reduction than the smoother ones.     

Swelling and morphology of the skin layer of polyamide composite membranes: an atomic force microscopy study

The paper introduces a new methodology for studying polyamide composite membranes for reverse osmosis (RO) and nanofiltration (NF) in liquid environments. The methodology is based on atomic force microscopy of the active layer, which had been separated from the support and placed on a solid substrate. The approach was employed to determine the thickness, interfacial morphology, and dimensional changes in solution (swelling) of polyamide films. The face (active) and back (facing the support) surfaces of the RO films appeared morphologically similar, in agreement with the recently proposed model of skin formation. Measured thickness and swelling data in conjunction with the intrinsic permeability of the membranes suggest that the selective barrier in RO membrane constitutes only a fraction of the polyamide skin, whereas NF membranes behave as nearly uniform films. For NF membranes, there was reasonable correlation between the changes in the swelling and in the permeability of the membrane and the salinity and pH of the feed.     

超滤/纳滤技术深度处理肠衣废水的研究

采用超滤/纳滤技术对肠衣废水进行深度处理,研究操作压力和处理时间对膜性能的影响。结果表明,适宜的超滤压力为0.25MPa,运行1h后,肠衣废水的COD(chemical oxy-gen demand)、BOD(biochemical oxygen demand)的平均去除率分别大于60%和35%,平均膜通量大于580L/(m2.h);适宜的纳滤压力为1.4～1.6MPa,连续运行3h后,肠衣废水COD、BOD和氯离子的平均去除率分别大于70%、90%和98%,平均膜通量大于60L/(m2.h);最终出水的水质可以达到中水回用的要求。