反渗透膜在葡萄酒酿造中的应用

论述了采用反渗透膜浓缩葡萄汁的工艺流程、技术条件.     

反渗透膜在葡萄酒酿造中的应用

论述了采用反渗透膜浓缩葡萄汁的工艺流程、技术条件。     

反渗透膜支撑体的制备

经硬挺整理后的涤纶针织物可作为反渗透膜的支撑体.探讨了整理剂选择的制约因素以及整理剂组分质量比对整理效果的影响,分析了整理剂用量、预烘温度、焙烘温度和焙烘时间等因素对织物性能的影响,并得出最佳整理工艺:整理剂[m(聚醋酸乙烯酯):m(环氧树脂)=7:1]用量为500 g/L,预烘温度110℃,190℃焙烘1.5 min.通过扫描电镜观察了整理前后织物的表面形态,结果表明:整理后织物的表面形成了硬挺整理剂薄膜,且分布均匀、致密.整理后织物强力和白度有所下降,但仍符合客户要求.     

热水反渗透膜在饮料行业的应用

通过对热水反渗透膜的主要特征、膜元件的技术参数特征、配套设备定位清洗（Cleaning in Place,CIP）CIP系统、膜自身清洗等方面的介绍,阐明热水反渗透膜和热水反渗透膜配套设备的特点即耐高温、可彻底清洗、能经受各种在线CIP清洗。实验证明在饮料行业中,使用热水反渗透膜系统不仅可以保证原水预处理系统出水水质符合卫生要求,而且可以完全避免普通反渗透系统由于支路多、盲管长等因素导致的系统自身滋生细菌、无法彻底清洗的问题,也解决了反渗透系统在微生物污染后无法彻底恢复的问题。     

Biofilm formation and cell surface properties of Staphylococcus aureus isolates from various sources

Food Science and Biotechnology - This study investigated biofilm formation, cell surface hydrophobicity, colony spreading, and slime production for 112 Staphylococcus aureus strains isolated from...     

Biofilm formation of Staphylococcus aureus dairy isolates representing different genotypes

The objective of this study was to compare the biofilm-forming capabilities of different genotypes of Staphylococcus aureus dairy isolates from Switzerland and northern Italy, including Staph. aureus genotype B (GTB) and methicillin-resistant Staph.aureus (MRSA). We hypothesized that biofilm formation might be more pronounced in the contagious GTB isolates compared with other genotypes affecting individual animals. Twenty-four dairy isolates, including 9 MRSA, were further characterized by genotyping by using ribosomal spacer PCR, spa typing, biofilm formation under static and dynamic conditions, and scanning electron microscopy. The GTB isolates (n = 6) were more able to form biofilms than other genotypes at 37°C and at 20°C after 48 and 72 h of incubation in the static assay using polystyrene microtiter plates. This result was supported by scanning electron micrographs showing a GTB isolate producing strong biofilm with extracellular matrix in contrast to a genotype C isolate. Furthermore, none of the MRSA isolates formed strong biofilms in the static assay. However, some MRSA produced low or moderate amounts of biofilm depending on the applied conditions. Under dynamic conditions, a much more diverse situation was observed. The ability of GTB isolates to be strong biofilm formers was not observed in all cases, emphasizing the importance of growth conditions for the expression of biofilm-related genes. No specific genotype, spa type, or MRSA isolate could be categorized significantly into one level of biofilm formation. Nineteen percent of isolates behaved similarly under static and dynamic conditions. The results of this study expand our knowledge of different dairy-related Staph. aureus subtypes and indicate the benefit of genotyping when biofilms are studied.     

Desalination of mixed tannery effluent with membrane bioreactor and reverse osmosis treatment

A limiting factor for the reuse and recycling of treated tannery wastewater for irrigation and other uses is the high salt content, which persists even after conventional treatment. Reverse osmosis (RO) membrane treatment has been shown to significantly reduce the salt contents of tannery effluents. However, the high organic content of tannery effluent leads to rapid scaling and biofouling of RO membranes with a consequent reduction in flux rates and performance. Membrane bioreactors (MBR) have been shown to be highly effective in the removal of organic pollutants and suspended solids from tannery effluent. This research investigated the use of a combined MBR and RO treatment process to treat tannery effluents to an acceptable level for irrigation purposes. The MBR was operated at 17-20 h retention time, at a F/M ratio of 0.52 kg COD x kg SS(-1) x day(-1) and a volumetric loading rate of 3.28 kg COD x m(-3) x day(-1). This treatment reduced the COD, BOD, and ammonia concentrations of the effluent by 90-100%. The MBR was shown to be an excellent pretreatment prior to RO technology, due to the high removal efficiency of organic compounds and suspended solids, with average concentrations of 344 mg x L(-1) COD and 20 mg x L(-1) BOD achieved in the permeate. RO treatment reduced the salt content of the MBR permeate by up to 97.1%. The results of the research demonstrated that the MBR system developed was appropriate for the treatment of tannery effluents and, in combination with the RO treatment, reduced the salt content to acceptable levels for irrigation. The MBR pretreatment reduced bio-fouling and scaling of subsequent RO treatment and improved the overall performance of the RO unit. It is believed that this is the first investigation of a combined MBR and RO treatment for tannery effluents. This research provided data for an outline design of a full-scale MBR and RO plant with a treatment capacity of 5000 m3 per day for mixed tannery effluents.     

反渗透膜的性能研究及在造纸废水处理中的应用

本文研究了反渗透膜BW30和X-20操作压力对膜通量和脱盐率的影响、离子半径对脱盐率的影响。实验结果表明:当操作压力从0.1MPa升高到0.2MPa时,两种膜对盐溶液的通量分别从0.59 L/(m2·h)上升到1.99 L/(m2·h),从0.34 L/(m2·h)上升到1.36 L/(m2·h),而脱盐率从30%下降到20%左右,随着离子半径的增大,膜的脱盐率依次增大;并研究了反渗透膜在造纸废水处理中的应用。实验结果表明:纳滤膜对小分子有机物有很好的截留、脱盐效果明显,并且对色度、浊度有很好的去除能力。     

Comparison of methods for assessing reverse osmosis membrane treatment of shrimp process water

Interest in reuse of process water from the food industry has reinforced the importance of controlling and monitoring the effectiveness and reliability of treatment systems regarding removal of organic matter and microorganisms. The ability of adenosine triphosphate bioluminescence, conductivity, turbidometry, absorbance, and multichannel fluorescence spectroscopy for indirectly monitoring the integrity of a reverse osmosis membrane when treating process water recovered from peeling in a shrimp processing line was evaluated. This study demonstrated that reverse osmosis was capable of removing bacteria (ca. 7 log CFU ml(-1)) to the levels required by the regulatory authorities for water recycling within the same food unit operation. Adenosine triphosphate and turbidometry showed a higher sensitivity for detecting compromising conditions at the treatment system (0.1% concentration of feed in permeate) and a better correlation with the aerobic count at lower levels than the other methods investigated. The sensitivity for assessing membrane integrity of conductivity and multichannel fluorescence was 1% of feed in permeate. Impact of feed variations was best leveled out in the permeates for turbidity measurements. Multichannel fluorescence spectroscopy may require laborious calibration procedures and expertise regarding data analysis and interpretation of results, which are not always available in food industries. Absorbance did not respond to changes in membrane integrity and was not well correlated to the aerobic count because of the poor sensitivity of this method for these purposes.     

Feed substrates influence biofilm formation on reverse osmosis membranes and their cleaning efficiency

The dairy industry is increasingly using reverse osmosis (RO) membranes for concentration of various fluid feed materials such as whey and ultrafiltration (UF) permeate. This study compared the effect of UF permeate and whey on membrane biofilm formation. A Bacillus sp., previously isolated in our laboratory from a cleaning-resistant membrane biofilm, was used to develop 48-h-old static biofilms on RO membrane pieces, using the different feed substrates (UF permeate, whey, and an alternating whey/UF feed). Biofilms were analyzed for viable counts by the swab technique, and we used scanning electron and atomic force microscopy for microstructure imaging. The membrane cleaning process included 6 sequential steps. We observed differences in the resistance pattern of the 3 types of biofilms to the typical cleaning process. The mean pretreatment counts of the 48-h UF permeate biofilms were 5.39 log cfu/cm², much higher than the whey biofilm counts of 3.44 log, and alternating whey/UF biofilm counts of 4.54 log. After a 6-step cleaning cycle, we found 2.54 log survivors of the Bacillus isolate on UF biofilms, whereas only 1.82 log survivors were found in whey biofilm, and 2.14 log survivors on whey/UF permeate biofilms. In conclusion, the UF permeate biofilms was more resistant to the biofilm cleaning process compared with the whey or whey/UF permeate biofilms. Scanning electron micrographs showed different microstructures of biofilms based on the type of feed. For UF permeate and whey/UF permeate biofilms, bacilli were present in multilayers of cells in aggregates or irregular clusters with foulant layers. In contrast, those in whey biofilms were in monolayers, with a smoother, flatter appearance. Atomic force microscopy analysis indicated that UF permeate biofilms had the greatest surface roughness among the biofilms, reflecting intensified bacterial colonization. The biofilm micro- and nanostructure variations for the 2 feed substrates and their combination may have resulted in differences in their resistance to the cleaning process.     

Manufacture of direct acidified cheese from ultrafiltration and reverse osmosis retentates

Whole milk and retentates from ultrafiltration at 4:1 volume concentration ratio and reverse osmosis at 2.5:1 were used in the manufacture of direct acidified cheese. Yield based on component recovery was higher in cheese from milk retentates than whole milk. On a dry mass basis, an increase in cheese yield of 37.9% for reverse osmosis, and 14.7% for ultrafiltration was achieved compared with cheese from whole milk. Compositional variation in the resulting cheese affected both textural and sensory parameters. Cheese from ultrafiltration scored highest in sensory evaluation, although all cheeses were graded fair to good.     

Influence of partial dealcoholization by reverse osmosis on red wine composition and sensory characteristics

Two red wines with a very high ethanol content were partially dealcoholized by reverse osmosis, so that the influence of this technique on wine color, chemical composition and sensory quality could be studied. No statistically significant differences were found in pH, color intensity, total phenolic index, proanthocyanidin concentration and their mean degree of polymerization between control wines and partially dealcoholized wines (?1 and ?2 vol. %). Some slight but significant differences were found in titratable acidity, anthocyanins, CIELab coordinates and polysaccharides. However, these differences were really quite small and only significant in a few cases. Moreover, a trained panel of tasters had severe difficulty in distinguishing between control and partially dealcoholized wines in triangular tests, and results were statistically significant only in some of the comparisons. It is concluded that this technique can be very useful for the partial dealcoholization of red wines because they hardly alter their composition and sensory characteristics.     

Community structure analysis of reverse osmosis membrane biofilms and the significance of Rhizobiales bacteria in biofouling

The biofilm community structure of a biofouled reverse osmosis (RO) membrane was examined using a polyphasic approach, and the dominant phylotypes retrieved were related to the order Rhizobiales, a group of bacteria that is hitherto not implicated in membrane biofouling. A comparison with two other membrane biofilms using T-RFLP fingerprinting also revealed the dominance of Rhizobiales organisms. When pure culture RO biofilm isolates were cultivated aerobically in BIOLOG microplates, most Rhizobiales were metabolically versatile in their choice of carbon substrates. Nitrate reduction was observed in five RO isolates related to Castellaniella, Ochrobactrum, Stenotrophomonas, and Xanthobacter. Many of the key Rhizobiales genera including Bosea, Ochrobactrum, Shinella, and Rhodopseudomonas were detected by PCR to contain the nirK gene responsible for nitrite reductase activity. These findings suggest that Rhizobiales organisms are ecologically significant in membrane biofilm communities under both aerobic and anoxic conditions and may be responsible for biofouling in membrane separation systems.     

Uranium biomineralization as a result of bacterial phosphatase activity: insights from bacterial isolates from a contaminated subsurface

Uranium contamination is an environmental concern at the Department of Energy's Field Research Center in Oak Ridge, Tennessee. In this study, we investigated whether phosphate biomineralization, or the aerobic precipitation of U(VI)-phosphate phases facilitated by the enzymatic activities of microorganisms, offers an alternative to the more extensively studied anaerobic U(VI) bioreduction. Three heterotrophic bacteria isolated from FRC soils were studied for their ability to grow and liberate phosphate in the presence of U(VI) and an organophosphate between pH 4.5 and 7.0. The objectives were to determine whether the strains hydrolyzed sufficient phosphate to precipitate uranium, to determine whether low pH might have an effect on U(VI) precipitation, and to identify the uranium solid phase formed during biomineralization. Two bacterial strains hydrolyzed sufficient organophosphate to precipitate 7395% total uranium after 120 h of incubation in simulated groundwater. The highest rates of uranium precipitation and phosphatase activity were observed between pH 5.0 and 7.0. EXAFS spectra identified the uranyl phosphate precipitate as an autunite/meta-autunite group mineral. The results of this study indicate that aerobic heterotrophic bacteria within a uranium-contaminated environment that can hydrolyze organophosphate, especially in low pH conditions, may play an important role in the bioremediation of uranium.     

小型一体化反渗透设备的运行管理

根据小型一体化反渗透设备的结构特点,介绍了设备安装和使用过程中常出现的一些问题及其解决方法,加强运行管理能有效地提高反渗透设备的使用寿命。     

超滤和反渗透技术在果汁生产中的应用

根据超滤膜和反渗透膜的特点，介绍了超滤(UF)和反渗透(RO)膜技术在苹果汁、橘子汁、山楂汁等果汁生产中的应用。     

反渗透技术在垃圾渗滤液净化处理中的应用

反渗透分离技术能有效截留垃圾渗滤液中溶解态的有机和无机污染物，在国外已广泛用于渗滤液的净化处理中，对现有的垃圾渗滤液反渗透净化处理工艺进行了总结，包括反渗透、高压反渗透、纳滤、膜组合、综合处理等工艺。这种垃圾渗滤液净化处理新技术符合我国政府的环保产业政策，应尽快得到应用和推广。     

管式反渗透浓缩牛奶的实验研究

介绍了采用管式反渗透膜浓缩牛奶的工艺,研究了工艺中的压力、温度、浓度和浓缩过程与牛奶中有效成分的截留率之间的关系,同时也研究了压力、温度、浓度在浓缩过程中与膜通量之间的关系。实验结果证明,管式反渗透膜对有效成分的截留率接近100%。     

Quality evaluation of grape juice concentrated by reverse osmosis

The objective of this work was to evaluate the concentration of grape juice by reverse osmosis (RO). Preliminarily, a factorial design was carried out in which the independent variables were transmembrane pressure (40, 50 and 60 bar) and temperature (20, 30 and 40 °C) of the process, and the dependent variables were pH, content of soluble solids, acidity, concentration of phenolic compounds and those of monomeric and total anthocyanins, colour index, colour density, and permeate flux. None of the experiments resulted in significant changes in the juice characteristics. The best process conditions, 60 bar transmembrane pressure and 40 °C, was selected based on the resulting high permeate flux value. Subsequently, a new trial was performed in order to determine whether increasing the temperature from 40 to 50 °C would result in any changes in the juice characteristics. The transmembrane pressure was kept at 60 bar, which was also the maximum value that could be applied by the equipment. Under these conditions, an increase in permeate flux was achieved with no significant difference in the physical or chemical parameters of the product compared to the best condition corresponding to the factorial design. The physical and chemical properties of the concentrated juice increased in proportion to the volumetric concentration factor, indicating the technical feasibility of reverse osmosis for pre-concentrating grape juice.