Resistance of the constitutive microflora of biofilms formed on whey reverse-osmosis membranes to individual cleaning steps of a typical clean-in-place protocol

This experiment evaluates the effectiveness of individual steps of a clean-in-place protocol against the biofilm constitutive microflora isolated from the biofilms developed on whey reverse-osmosis membranes, aged 2 to 14 mo, under industrial processing conditions. The isolates used for the in vitro resistance studies included species of Bacillus, Enterococcus, Streptococcus, Staphylococcus, Micrococcus, Aeromonas, Corynebacterium, Pseudomonas, Klebsiella, and Escherichia. The 6 cleaning steps (alkali, surfactant, acid, enzyme, a second surfactant, and sanitizer treatment) revealed resistance of isolates in both planktonic and biofilm-embedded cell states. The most effective step was the acid treatment, which resulted in 4.54 to 7.90 and 2.09 to 5.02 log reductions of the planktonic and biofilm-embedded cells, respectively. Although the sanitizer step causing a reduction of 4.91 to 8.33 log in the case of planktonic cells, it was less effective against the biofilm-embedded cells, resulting in a reduction of 0.59 to 1.64 log. Bacillus spp. showed the highest resistance in both planktonic, as well as embedded cell states.     

Microscopic observation of multispecies biofilm of various structures on whey concentration membranes

The objective of this study was to evaluate biofilm formation on polyamide reverse osmosis (RO) whey concentration membranes. Biofilms were observed with scanning electron and fluorescence microscopy. For scanning electron microscopy, pieces of 6-, 12-, and 14-mo-old membranes were allowed to air dry at room temperature (22°C) for 24 h followed by sputter coating with a 5-nm layer of gold and microscopic observations. Scanning electron microscopy images revealed that the hydrophilic layer, used to prevent membrane plugging, was not evenly distributed on the surface. Although this hydrophilic layer seemed to prevent the attachment of proteins, it supported biofilm formation. Three different structures of multispecies biofilm were observed on the retentate side of the membrane: 1) a mono layer, 2) a 3-dimensional structure of a dense matrix of extracellular polymeric substances where different types of bacterial cells were embedded, and 3) cell aggregates. In some of the biofilms, a smooth layer (shell) covered cell aggregates. In the 6-mo-old membranes, part of the shell layer was broken off. Biofilms as observed on the RO membrane were described as having a hill-and-valley type of structure, with hills showing a mushroom-like appearance and valleys comprising dense matrices of extracellular polymers with embedded bacterial cells. Fluorescence microscopy showed live cells on the surface of the biofilm. It is concluded that both cells in the deep layers of biofilm and surface cells may resist cleaning and sanitation. The extent of biofilm formation and the presence of live cells on RO membranes after regular clean in place cycles indicate the need for a more effective cleaning regimen customized for dairy separation systems.     

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。     

充分利用供应商技术优势降低反渗透系统运行成本

利用供应商的专家技术优势，采用专业阻垢剂，定期洗膜，以确保系统的安全运转。实践证明运转效果良好，可大大降低公司运行成本。     

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.     

印染废水的超滤/反渗透膜法深度处理回用

采用超滤/反渗透膜法深度处理印染废水,并回用于染色工序。实践表明,出水各项指标均优于HJ471—2009《纺织染整工业废水治理工程技术规范》中的染色回用水水质标准。其中,出水色度为2倍,电导率为17μS/cm,COD及SS均未检出。     

Effect of pH adjustment on the composition and rennet-gelation properties of milk concentrates made from ultrafiltration and reverse osmosis

The objective of this work was to investigate the effect of pH adjustment (initial pH vs. pH 6.50) on the rennet-gelation properties of concentrates made by ultrafiltration (UF) and reverse osmosis (RO). Rennet-gelation kinetics were followed by dynamic rheology and κ-casein hydrolysis by reverse-phase HPLC. At initial pH, RO concentrates had better rennet-coagulation behavior than UF concentrates and skim milk, whereas adjusting the pH to 6.50 produced the opposite results. The kinetics of κ-casein hydrolysis were similar in skim milk, and both concentrates and were not affected by pH adjustment. Differences in rennet coagulation were then related to the extent of hydrolysis required to trigger casein micelle aggregation. Small pH adjustments (<0.2 pH unit) enabled the use of RO concentrate with similar rennet-gelation behavior to UF concentrate, despite major compositional differences. This study shows that pH adjustment of RO concentrates can be a simple approach to improve their coagulation properties; however, the mechanisms behind these improvements remain to be elucidated.     

反渗透浓缩籽瓜汁的实验研究

采用反渗透技术对籽瓜汁进行浓缩,分别研究了膜通量、压力、料液温度、籽瓜汁浓度等参数之间的关系,结果表明:反渗透膜对籽瓜汁有效成分的截留率接近100%,对无机盐截留率大于98%,籽瓜汁的最终浓缩浓度为20Brix;其它条件不变的情况下,膜通量与压力、料液温度成正比关系,与料液浓度成反比关系。      

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.     

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。     

The effects of biofilms formed on whey reverse osmosis membranes on the microbial quality of the concentrated product

The study investigated the development of bacterial biofilms on spiral wound reverse osmosis (RO) whey concentration membranes and their influence on the microbial quality and safety of concentrated whey (retentate). Used RO membranes, obtained from a commercial whey processing plant, were evaluated at intervals of 2 months for a total duration of 14 months using standard techniques. Results confirmed the presence of multi‐species bacterial biofilms on whey RO membranes. Considerable variations were noticed in the distribution pattern of biofilms constitutive microflora as the membranes aged. A greater increase in retentate counts as compared to feed suggested the possibilities of cross‐contamination from the membrane biofilms.     

离子交换与反渗透法生产纯水工艺比较

本文叙述了离子交换与反渗透除盐生产纯水两个工艺,结合吉恩镍业的生产实际,进行了工艺流程及特点比较,并针对现场生产遇到的实际问题,提出因原水水质恶化和精矿成分变化,导致除盐水供应量不足时的解决方案.     

Effect of reverse osmosis and ultra-high-pressure homogenization on the composition and microstructure of sweet buttermilk

Buttermilk (BM), the by-product of butter making, is similar to skim milk (SM) composition. However, it is currently undervalued in dairy processing because it is responsible for texture defects (e.g., crumbliness, decreased firmness) in cheese and yogurt. One possible way of improving the incorporation of BM into dairy products is by the use of technological pretreatments such as membrane filtration and homogenization. The study aimed at characterizing the effect of preconcentration by reverse osmosis (RO) and single-pass ultra-high-pressure homogenization (UHPH) on the composition and microstructure of sweet BM to modify its techno-functional properties (e.g., protein gel formation, syneresis, firmness). The BM and RO BM were treated at 0, 15, 150, and 300 MPa. Pressure-treated and control BM and RO BM were ultracentrifuged to fractionate them into the following 3 fractions: a supernatant soluble fraction (top layer), a colloidal fraction consisting of a cloudy layer (middle layer), and a high-density pellet (bottom layer). Compositional changes in the soluble fraction [lipid, phospholipid (PL), protein, and salt], as well as its protein profile by PAGE analysis, were determined. Modifications in particle size distribution upon UHPH were monitored by laser diffraction in the presence and absence of sodium citrate to dissociate the casein (CN) micelles. Microstructural changes in pressure-treated and non-pressure-treated BM and RO BM particles were monitored by confocal laser scanning microscopy. Particle size analysis showed that UHPH treatment significantly decreased the size of the milk fat globule membrane fragments in BM and RO BM. Also, pressure treatment at 300 MPa led to a significant increase in the recovery of total lipids, CN, calcium, and phosphate in the BM soluble fraction (top layer) following ultracentrifugation. However, PL were primarily concentrated in the pellet cloud (middle layer), located above the pellet in BM concentrated by RO. In contrast, PL were evenly distributed between soluble and colloidal phases of BM. This study provides insight into the modifications of sweet BM constituents induced by RO and UHPH from a compositional and structural perspective.     

反渗透技术在果蔬汁浓缩中的应用研究

利用反渗透技术对几种果蔬汁（ 黄瓜、芹菜、胡萝卜、枸杞子、红杏） 的浓缩处理进行实验与分析。结果表明在一定条件下, 通过反渗透方法可对果胶含量低的果蔬汁直接进行浓缩处理, 并且浓宿倍数超过１０ 倍以上。而果胶含量较高的果汁则需要预先进行酶解脱胶后再进行浓缩。实验中发现果胶的含量直接影响浓缩的程度与效果。结果分析认为反渗透在果蔬汁的浓缩加工方面确实可行。还对各类果蔬汁的制取、脱胶、浓缩加工处理模式做了分析探讨。     

Amelioration of smoke taint in wine by reverse osmosis and solid phase adsorption

Background and Aims: Wines made from grapes harvested from vineyards exposed to bushfire smoke can exhibit objectionable ‘smoky’, ‘cold ash’, ‘medicinal’ and ‘ashy’ aroma and flavour characters. This study evaluated a combined reverse osmosis and solid phase adsorption process as a potential amelioration method for the treatment of smoke‐tainted wines. Methods and Results: Smoke‐tainted wines were treated using either pilot or commercial scale reverse osmosis systems and the chemical composition and sensory properties of wine compared before and after treatment. The concentrations of smoke‐derived volatile phenols, including marker compounds, guaiacol and 4‐methylguaiacol, decreased significantly with treatment. As a consequence, diminished smoke‐related sensory attributes enabled treated wines to be readily differentiated from untreated wines. However, the taint was found to slowly return with time, likely because of hydrolysis of glycoconjugate precursors, which were not removed during the treatment process. Conclusions: Reverse osmosis and solid phase adsorption reduced the concentration of smoked‐derived volatile phenols and improved the sensory attributes of smoke‐tainted wines. Significance of the Study: This is the first study to evaluate the amelioration of smoke taint in wine using reverse osmosis and solid phase adsorption.     

Preparation and composition of chhana whey powders using membrane processing techniques

Chhana is a traditional Indian product used widely in the confectionery industry. It is produced from cow's milk by a combination of heat and acid coagulation. Chhana whey contains about 6% milk solids yet the vast majority is wasted which leads to pollution problems. This study describes the chemical composition and various options for utilisation of chhana whey using membrane processes. Chhana whey powder containing 956 g kg^?1 total solids, 750 g kg^?1 lactose, 21 g kg^?1 protein. 60 g kg^?1 fat, 65 g kg^?1 ash was produced following concentration of chhana whey by reverse osmosis. Chhana whey protein concentrate powders containing 270, 350, 400 and 580 g kg^?1 protein were produced following ultrafiltration or diafiltration of chhana whey.     

Growth performance and health of dairy calves given water treated with a reverse osmosis system compared with municipal city water

Our objective was to determine effects of drinking reverse osmosis water (RW) versus municipal city water (MW) on growth, nutrient utilization, and health scores of calves. Twenty-four Holstein calves (14 females, 10 males; 2 d old; 44.6 ± 6.10 kg of body weight), housed in individual hutches, were used in a 10-wk randomized complete block design study. Calves were blocked by birthdate and sex. Treatments were RW (Culligan Water Filtration System, Brookings, SD) versus MW (Brookings Municipal Utilities, Brookings, SD) that contained 13 and 387 mg/L of total dissolved solids, respectively. Milk replacer (28% crude protein; 18% fat) was fed twice daily during wk 1 through 5 and then once daily during wk 6. At each feeding, 0.45 kg of dry milk replacer was mixed with 2.83 L of the respective water type according to treatment. Calves were fed water, respective to treatment, and calf starter pellets ad libitum throughout the study. All intakes were recorded daily. Daily total respiratory scores (healthy ≤3, sick ≥5) were calculated from the sum of scores for rectal temperature, cough, and ocular and nasal discharges. Fecal consistency scores (0 = firm, 3 = watery) were also recorded daily. Body weights and frame growth were measured 2 d every 2 wk and jugular blood samples were collected 1 d every 2 wk at 3 h after the morning feeding. Fecal grab samples were collected 5 times per day for 3 d during wk 10 for analysis of apparent total-tract digestibility of nutrients. We found treatment by week interactions for dry matter intake and gain-to-feed ratio, and total dry matter intake increased more during the study for RW than MW. Gain-to-feed ratio was greater during the first few weeks of the feeding period for RW compared with MW and then comparable during the rest of study. Water intake was less in RW than MW, potentially indicating more efficient water use by calves. Frame growth, body weight, average daily gain, serum glucose, plasma urea nitrogen, β-hydroxybutyrate, total-tract digestibility of dry matter, and crude protein were similar. Fecal scores tended to be lower (firmer) in calves on RW, with an interaction by time. Respiratory scores decreased during the weaning period when calves drank RW. Results demonstrated calves drinking RW had similar growth and improved health scores with treatment by time interactions compared with MW.     

食品工业中阪崎克罗诺杆菌生物膜形成的影响因素与控制策略研究进展

阪崎克罗诺杆菌是一种食源性条件致病菌,它可以引起不同年龄段人群的感染,对于新生儿和免疫功能不全的婴幼儿的威胁尤为严重,引起的症状包括坏死性小肠结肠炎、菌血症、脑膜炎和术后骨髓炎等。在食品生产环境以及设备表面由阪崎克罗诺杆菌形成的生物膜是持久性污染食品的重要来源。因此本文主要综述了在食品工业中阪崎克罗诺杆菌流行病学、生物膜形成的机制以及生物膜控制的策略,旨在为建立安全的无生物膜食品生产环境体系,控制阪崎克罗诺杆菌所致食品的潜在污染以及临床感染提供理论指导。      

活性污泥-浸没式超滤-反渗透在针织印染废水回用处理中的应用

采用活性污泥-气浮+浸没式超滤-反渗透工艺处理针织印染废水,发现二级处理段CODCr、氨氮、总磷去除率分别达到90%、74%、89%,色度、pH值达接管要求,优于一期出水水质。深度处理段,超滤出水达到一般回用水要求,回用产水池水质完全达到针织印染各生产工艺要求。回用水处理成本低于新鲜水与废水处理费用之和,节省了水资源,提升了水重复利用率。