Development of energy-saving spinning membrane systemand negatively charged ultrafiltration membranes for recovering oil from waste machine cutting fluid

Membranes with hydrophobic surfaces have higher tendency for protein adsorption and bacteria attachment.As a result, these membranes foul rapidly in cross-flow filtration processes. Changing the membrane surface properties can slow down the membrane fouling process. For difficult membrane separation processes like oilwater emulsion separation, changing membrane properties alone cannot slow down the membrane fouling process. The ordinary cross-flow filtration system cannot be successfully employed for this kind of separation, and the spinning membrane disc system could be considered. The conventional spinning membrane disc system however is not energy efficient due to the centrifugal force acting against the permeate flow; this reduces the effective filtration pressure during the separation operation. Efforts were undertaken to develop a group of negatively charged ultrafiltration membranes, prepared from polyacrylonitrile-vinyl acetate-sodium p-sulfophenyl methallyl ether (CP-24) with polyacrylonitrile-vinyl acetate (CP-16), to be used in an energy-saving design of spinning membrane disc separation system. Our experimental results clearly demonstrate the energy saving benefit of our design; at filtration pressure of 276 kPa and at membrane disc spinning velocity of 1,000 rpm without sacrificing the oil rejection (>98% for 1,000 ppm oil-in-water) by our membrane, the permeate velocity was increased as high as 132% by our energy-saving system over conventional spinning membrane disc separation system.     

高频振动膜处理含油污水实验研究

使用机械振动和超滤组件结合的高频振动剪切超滤膜过滤系统,来考察振动频率、进口压力、料液流量等因素对膜系统渗透通量和分离性能的影响。利用清水、含油污水和0．1％NaOH溶液来研究高频振动剪切超滤膜过滤系统的性能,对比了常规静态错流膜过滤与高频振动剪切膜过滤,验证振动剪切膜过滤方式的可行性和有效性。     

Membrane choice for wastewater treatment using external cross flow tubular membrane filtration

Systematic investigations of activated sludge separation were conducted using membrane filtration. To accomplish this, different organic tubular membranes with different separation limits and diameters were examined. Furthermore, from the results obtained in the initial tests, an appropriate membrane was chosen for a long-term test. The investigations determined that for biomass separation by the tubular membranes in the tested system, neither the membrane material nor the separation limit within a range of 1 μm to 20,000 Da had a significant influence on the filtration characteristics. It was recognized that the application of a tubular membrane with a diameter of less than 8 mm is problematic, because high flow velocities were needed to prevent blockage of the membrane. When the flow velocity was in the range of 1 to 4 m/s, a linear relation between flux and velocity was found. This showed the potential for controlling the membrane filtration process and externally influencing the permeate rate. An average retention of TOC was about 75%. The retention of TOC was not significantly influenced by the nominal pore sizes of the membranes (except for the membrane WFNX 0505) which were tested here. The ultrafiltration membrane WFS 0120 (Stork) was prominent in the long-term test due to its very high flux, germfree permeate with a MWCO (molecular weight cut-off) of 100,000 Da, and was not blocked with a diameter of 14.4 mm, also at lower flow velocities. The results of the long-term test supported the hypothesis that a meaningful application of such a module concept is possible in a filtration plant for the preparation of samples or for the rejection of the biomass in small sewage treatment plants.     

Zirconium and Hafnium Separation,Part 3. Ligand‐Enhanced Separation of Zirconium and Hafnium from Aqueous Solution using Nanofiltration

Abstract

Membrane filtration equipment was used to evaluate zirconium and hafnium separation efficiency by a membrane separation process. High rejection of Zr and Hf species in aqueous solution were obtained with nanofiltration and ultrafiltration membranes. This high rejection could be explained by the formation of high molecular weight polynuclear species. Enhanced transportation across the nanofiltration and ultrafiltration membranes was observed when aminocarboxylic ligands, like EDTA, were introduced in the solution. This enhancement could be explained by a depolymerization process of the polynuclear complexes induced by the ligands. The rejection of Zr and Hf was markedly influenced by the counter anions and the EDTA/metal ratio. By using Zr and Hf oxynitrates instead of oxychlorides a difference of rejection of up to 20% was observed for Zr and Hf indicating that the membrane separation process could be an alternative process for Zr and Hf separation.     

投加粉末活性炭对超滤膜去除海水中有机物的影响

超滤膜的有机污染问题是膜法海水预处理技术在海水淡化工程应用面临的重要挑战,粉末活性炭吸附是目前常用的膜前预处理手段之一。本文对比分析了直接超滤和投加粉末活性炭后对海水中有机物的截留能力,利用三维荧光光谱分析了投加粉末活性炭对超滤膜截留有机物的影响机制,并考察了海水超滤过程中通量变化及膜污染情况。研究结果表明,投加粉末活性炭能够强化超滤膜对海水浊度和有机物的去除,当粉末活性炭投量为200mg/L时,整个系统对海水中DOC去除率从直接超滤时的55.1%提高到77.6%。利用粉末活性炭的吸附作用及其在超滤膜表面形成的疏松滤饼层能够显著提高超滤系统对海水中腐植酸类有机物的去除能力。与直接超滤相比,粉末活性炭-超滤系统对改善膜通量的作用有限,但粉末活性炭形成的滤饼层能够避免超滤膜与有机物直接接触,可显著减缓超滤膜的不可逆污染。     

Reducing pollution from the deliming–bating operation in a tannery. Wastewater reuse by microfiltration membranes

This paper presents experimental results from the implementation of two measures aimed at reducing the nitrogen concentration in a tannery wastewater. Specifically, this research has focused on the wastewater from the deliming/bating operations. The proposed measures are the replacement of ammonium salts by carbon dioxide in the deliming process and the reuse of wastewater and chemicals after membrane filtration of the deliming/bating liquor. The experimental study covered different wastewater pretreatment alternatives and experiments with two membranes (with different separation properties): one in the range of microfiltration (MF) and one in the range of the ultrafiltration (UF). Results of the pretreatment study indicated that neither settling nor protein precipitation were feasible. Only a security filtration prior to membrane filtration was recommended. The tested MF membrane was selected due to the higher flux (around 25 L/(m² h)) in comparison with the UF membrane. The MF permeate was successfully reused in the deliming/bating process. The delimed leather quality was excellent according to both visual and organoleptic inspection from process technicians and phenolphthalein test, confirming the technical feasibility of the proposal. Globally, the implementation of the above mentioned two measures resulted in 53% total nitrogen reduction.     

膜法绿色制糖技术研究进展

介绍了膜法绿色制糖技术在实验室、现场中试和示范工程方面的研究进展,对甘蔗压榨汁的澄清、脱色和浓缩提纯过程中的选膜研究进行了综述,分析比较了陶瓷膜和有机膜的优劣,重点介绍了膜浓缩液中残糖回收、膜污染机理及清洗策略,展望了膜法绿色制糖技术工业化亟需解决的问题.     

Funktionalisierung von Ultrafiltrationsmembranen zur Integration von spezifischen Adsorbereigenschaften

By integrating a water‐soluble polymer, which has the ability to complex heavy metal ions into ultrafiltration membranes, the separation process could be enhanced to enable also filtration of these species. In this work, a membrane and an adsorber polymer were functionalized with complementary reactive groups so that the adsorber polymer could be immobilized in the porous support layer of the ultrafiltration membrane via click reaction. The separation performances and membrane characteristics of the synthesized membranes are comparable to those of conventional UF membranes.     

A Study on Triple-Membrane-Separator (TMS) Process to Treat Aqueous Effluents Containing Uranium

Abstract

An effective process incorporated with the novel membrane separation technology was developed to recover uranium from the filtrate effluent of uranium dioxide conversion processes. The prominent feature of the process is that it utilizes separation characteristics of three different types of membranes as follow: separation of uranium species from effluent of high fluoride content by ultrafiltration membrane, separation of uranium species from effluent of low fluoride content by reverse osmosis membrane, precipitation of uranium species with hydrogen peroxide, and filtration of uranium bearing precipitates by microfiltration membrane. The process is simple and feasible for treatment of liquid waste containing both soluble and suspended uranium species. The recovery of uranium can achieve 95% and the treated effluents meet the current environmental standards.     

用活性炭吸附强化超滤过程脱除废水中染料的研究(英文)

In this study, orange G dye was efficiently removed from aqueous solution by ultrafiltration (UF) mem-brane separation enhanced with activated carbon adsorption. The powdered activated carbon (PAC) was deposited onto the UF membrane surface, forming an intact filter cake. The enhanced UF process simultaneously exploited the high water permeation flux of porous membrane and the high adsorption ability of PAC toward dye molecules. The influencing factors on the dye removal were investigated. The results indicated that with sufficient PAC incor-poration, the formation of intact PAC filtration cake led to nearly complete rejection for dye solution under opti-mized dye concentration and operation pressure, without large sacrificing the permeation flux of the filtration process. Typically, the dye rejection ratio increased from 43.6% for single UF without adsorption to nearly 100% for the en-hanced UF process, achieving long time continuous treatment with water permeation flux of 47 L·m 2·h 1. The pre-sent study demonstrated that adsorption enhanced UF may be a feasible method for the dye wastewater treatment.     

湿式催化氧化/膜过滤组合工艺膜过滤机理

采用湿式催化氧化/膜过滤组合工艺,以Mo-Zn-Al-O粉末作为催化剂降解阳离子红GTL模拟染料废水,探讨在膜过滤过程中平均孔径为0.1 μm的微滤和0.022 μm的超滤聚偏氟乙烯(PVDF)中空纤维膜的过滤机理。实验结果表明,两种膜过滤组合工艺对染料的降解效果均优于单独湿式催化氧化,0.01 MPa恒压条件下运行120 min后微滤和超滤的膜通量分别衰减了26.63%和16.48%,其原因是粉末催化剂可在微滤膜孔内部沉积形成中间阻塞过滤,后在表面形成滤饼层;而在超滤膜表面仅形成滤饼层。通过实验结果对膜阻力进行计算,可知在相同反应过程后微滤膜产生的不可逆阻力大于超滤膜。在不同反应条件下,催化剂的沉积量与膜阻力呈现线性相关。     

Membranes in the enzymatic synthesis of biotensides from renewable sources

A novel integrated process of enzymatic synthesis of sugar fatty acid esters from renewable sources was proposed for the system oleic acid/-methylglucoside focussing on the application of different membrane techniques. The operational parameters were studied and optimised carrying out the reaction in an enzymatic membrane reactor (EMR) where the catalyst remained retained by means of ultrafiltration. A pervaporation unit coupled to the EMR was applied for by-product removal (water). A proper product separation and isolation was achieved applying combined techniques including filtration, evaporation, extraction and alternatively stepwise elution chromatography or dialysis.     

Effect of process conditions on the removal of phospholipids from Jatropha curcas oil during the degumming process

This work aims to study the removal of phospholipids from Jatropha oil through a conventional degumming process combined with ultrafiltration membrane separation in a small-scale batch system. The effect of temperature, amount of acid solution added, and speed of centrifugation during the conventional degumming process were analyzed using response surface methodology (RSM). The optimum operating condition was determined to be at 65 °C, with 4 wt% acid solution added and a centrifugation speed of 1600 rpm. After the degumming process, the phospholipid content of Jatropha oil was reduced from 1200 ppm to 60 ppm. This was further reduced to less than 20 ppm by subjecting the oil to ultrafiltration membrane separation. It was found that the entire process not only decreased the phospholipid content of the oil but also improved its fuel properties, especially its kinematic viscosity and carbon residue. The kinematic viscosity was decreased from 30.02 cSt (mm²/s) to 27.20 cSt, while the carbon residue was decreased from 7.8% to 4.0%. Aside from the phospholipid content, the other two properties mentioned above were also considered to be important in the use of pure plant oil as a fuel in diesel engines. Future research could investigate the integration and optimization of the conventional degumming process combined with a membrane separation process.     

Amelioration of ultrafiltration process by lime treatment: Case of landfill leachate

Nowadays membrane ultrafiltration process is generally used in effluents treatment. However, at industrial level, this process has major limitations such as important membrane fouling. In this study, a pre-treatment with lime upstream ultrafiltration was envisaged. The effluent considered is landfill leachate. The final waste storage centres produce leachates resulting from the percolation of waters through the hidden waste mass. These effluents strongly charged in mineral and organic matters, must be treated before their release into natural environment. Concerning the cleaning up, results have shown that the selectivity of membranes has an important influence on elimination of pollution from organic source. As expected, any action of retention on salts and heavy metals has been shown. During the filtration of raw leachate, the fouling of membranes turns to be very important and does not allow reaching satisfactory productivity no matter the cut-off limit. There seems to be no impact from hydrodynamics on velocity circulation higher than 4 m s^− 1; this shows the existence of a dense and adhesive deposit on the membrane. The pre-treatment by lime allows (i) to precipitate carbonates under calcium carbonates form and ii) to eliminate by co-precipitation humic acids that are responsible for irreversible membrane fouling. Industrially, the implementation of the pre-treatment may allow reducing the costs of an ultrafiltration unit at about 50% in terms of investment and from 5 to 30% for operating costs.     

超滤组合工艺出水及消毒方法

本试验研究了用超滤组合工艺处理微污染水源的效果.探讨了该组合工艺出水的安全性及消毒方法.试验中采用的预处理技术是生物接触氧化和砂滤.研究表明,水温较低时,预处理对浊度、藻类和氨氮都有较好的去除效果,但对亚硝酸盐氮和有机物的去除作用有限;超滤膜除浊、除藻效果显著.该纽合工艺出水为生物不稳定水,并且有致突变性;要制备优质饮用水应改进工艺或应用新型消毒方法.     

Retention profile on the physicochemical properties of maize cooking by-product using a tight ultrafiltration membrane

Abstract

Maize cooking water is a common by-product of the agro-food processing industries. Such by-product is a current case of study for the research community. The present study analyzed the physicochemical properties of the extract during the ultrafiltration process at different weight reduction factor (WRF) values using a tight pore size membrane. The permeate samples coming from the filtration process were analyzed in terms of total soluble solids (TSS), total solids content (TSC), turbidity, pH, electrical conductivity, total polyphenols, total carbohydrates, and total organic carbon (TOC). At the end of the ultrafiltration process (WRF = 5), the retention efficiencies were of 100.0%, 78.4%, 30.5%, 32.6%, 43.8%, 75.9%, 79.9%, and 1.9% for TSS, TSC, turbidity, pH, conductivity, carbohydrates, TOC, and polyphenols, respectively. In this regard, it can be noticed that a significant quantity of the polyphenols contained in the initial extract was recovered in the permeate stream. According to the results, the selective filtration of this by-product by membrane technology represents a potential alternative for the recovery of its high-added value compounds. Finally, the highlighted results on polyphenol recovery are analyzed and discussed based on the separation process, molecule and membrane characteristics, and some other phenomena occurred in the recovery.     

Elimination of organic matter present in wastewaters from the cork industry by membrane filtration

BACKGROUND: The first stage of the cork industrial process generates great volumes of wastewater with moderate to high organic pollutant content that must be purified using different procedures, such as filtration by membranes. RESULTS: The tangential filtration of these wastewaters was studied using two different laboratory equipments. In the first one, three ultrafiltration (UF) membranes were tested, with molecular weight cut‐off (MWCO) 100 kDa and 30 kDa, and two operating modes were used: total recycling of permeate and retentate streams, and in continuous mode, without recycling both streams. In the total recycling UF experiments, the influence of the operating variables on the permeate flux was first established. The effectiveness of the different membranes was determined by evaluating the rejection coefficients for several parameters that measure the global pollutant content of the effluent. The values found for these rejection coefficients were in the following order: ellagic acid and color > absorbance at 254 nm > tannic content > COD (chemical oxygen demand). In the continuous mode experiments, the fouling mechanism for each membrane was established by fitting the experimental data to various filtration fouling models given in the literature. The operating mode in the second equipment was batch concentration, and additional experiments were carried out with an UF membrane (2 kDa), and with a NF membrane (with MWCO in the range 150–300 Da). CONCLUSIONS: The three operating modes tested provided different rejection levels of organic matter; among them, the most effective procedure tested was batch concentration mode using a NF membrane. Copyright © 2007 Society of Chemical Industry     

Investigating protein crossflow ultrafiltration mechanisms using interfacial phenomena

Protein separation mechanisms by a crossflow ultrafiltration membrane process are investigated using interfacial phenomena analysis of protein–protein and protein–membrane interactions. Varying operating conditions are used and membrane morphological parameters like hydrophilicity and hydrophobicity obtained from contact angle measurement. A single protein solution of bovine serum albumin (BSA) or ovalbumin (OV) or lysozyme (LY) is used in each filtration study case under various operating conditions, such as pH, ionic strength, and different polyethersulfone (PES) membranes with varying surface hydrophobicity and hydrophilicity. Under these conditions analyse of protein–membrane interfacial phenomena and protein separation filtration mechanisms are undertaken. Results indicate that electrostatic forces play an important role in protein deposition on the membrane surface and the rate of protein transmission across the membrane. Findings show that, at the proteins isoelectric point (pI), a hydrophobic membrane causes severe protein adsorption to the membrane surface, allowing a very small percentage of protein to be transported to the permeate side.     

Charged polyacrylonitrile membranes having amphiphilic quaternized ammonium groups for ultrafiltration

Four types of positively charged polyacrylonitriles having quaternized N,N-dimethylaminoethyl methacrylate (DAMA) were synthesized and were used to prepare ultrafiltration membranes by a phase-inversion method. The effect of aliphatic ethyl, octyl, and stearyl groups and the benzyl group, which covalently bind to the quaternary ammonium group, on filtration properties was studied by ultrafiltration under an applied pressure of 760 mmH₂O. Water permeability through the resultant membranes increased as the aliphatic chain length on the quaternary ammonium group increased. For a copolymer membrane having a benzyl group on the quaternary ammonium group, water permeability was lower than that for the ethyl type of copolymer membrane. The membrane permeability and pore size for the molecular size-exclusion effect were studied at various NaCl concentrations in the 0–0.15M region. The membranes having octyl and stearyl groups showed stable filtration behavior by increase of the NaCl concentration, while the membranes having an ethyl group and a benzyl group on the quaternary ammonium group showed a change of the water permeability due to a pore-size increase for the membrane by NaCl addition. Measurements of membrane potential indicated the shielding of positively charged sites of the membranes by salt addition. Further, the copolymer membranes showed a separation ability for water/2-butanol of low water content. The separation ability was attributed to the chemical structure of the membranes having different interaction characteristics with the mixture components. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1821–1828, 1998     

The numerical simulation of a new double swirl static mixer for gas reactants mixing

For the nitrogen oxide removal processes, high performance gas mixer is deeply needed for the injection of NH₃ or O₃. In this study, a new type of double swirl static mixer in gas mixing was investigated using computational fluid dynamics (CFD). The results obtained using Particle Image Velocimetry (PIV) correlated well with the results obtained from simulation. The comparisons in pressure loss between the experimental results and the simulation results showed that the model was suitable and accurate for the simulation of the static mixer. Optimal process conditions and design were investigated. When L/D equaled 4, coefficient of variation (COV) was < 5%. The inlet velocity did not affect the distributions of turbulent kinetic energy. In terms of both COV and pressure loss, the inner connector is important in the design of the static mixer. The nozzle length should be set at 4 cm. Taking both COV and pressure loss into consideration, the optimal oblique degree is 45°. The averaged kinetic energy changed according to process conditions and design. The new static mixer resulted in improved mixing performance in a more compact design. The new static mixer is more energy efficient compared with other SV static mixers. Therefore, the double swirl static mixer is promising in gas mixing.