用动态旋叶压滤机澄清菠萝汁的实验研究

动态过滤技术与膜技术相结合是目前固液分离领域的研究热点。采用澄清剂法澄清菠萝汁,存在缺陷。本文在动态旋叶压滤机中,研究了无机Ni膜和聚砜膜用于菠萝汁澄清过程的过滤特性。研究表明,无机Ni膜和聚砜膜澄清菠萝汁的膜通量分别是按指数和乘幂关系衰减的;果汁浓度和剪切速度的交互作用对膜通量有较大影响;无机Ni膜的通量显著高于聚砜膜的通量(3￣4倍),且无机Ni膜的稳定过滤时间比聚砜膜的稳定过滤时间长得多。     

流动形态对PVC支撑膜过滤自来水性能影响研究

研究了聚氯乙烯(PVC)支撑膜在不同流动形态下过滤自来水时的通量变化规律,分析了过滤压力以及流速对不同流动形态下膜过滤通量的影响,并用数学模型对实验数据进行了拟合,探讨了不同流动形态下膜过滤过程中的动力学变化规律。结果表明,垂直错流、平行错流及死端过滤时的平衡通量有显著差异。且与死端过滤和平行错流过滤相比,垂直错流过滤受过滤压力以及流速的影响更加显著。压力低于40 kPa时,垂直错流过滤过程中的过滤阻力受过滤压力的影响比较小,压缩指数在0.29～0.34变化,当过滤压力达到40 kPa时,过滤阻力受过滤压力的影响较为显著,压缩指数在0.78～0.86变化。为提高过滤能效,在垂直错流过滤时,过滤压力最好控制在40 kPa或以下。     

无机膜回收分子筛催化剂过程阻力的研究与测定

介绍了无机膜回收分子筛催化剂过程中的膜污染机理及影响因素,阐述了滤饼层的形成是膜污染的主要来源,同时对膜阻力进行了测定。得出实验所用的无机微滤膜在23℃、错流过滤速度2 m/s、操作压力为0.1 MPa的操作条件下过滤分子筛催化剂过程中所产生的总阻力Rt为3.26×1012m-1,污染所产生的阻力Rf为2.733×1012m-1,组件自身的阻力Rm为5.27×1011m-1,Rf约为Rm的5倍,是导致膜通量下降的主要原因。     

纳米镍在陶瓷膜表面的吸附行为研究

研究了纳米镍粉体在无机陶瓷平板膜面上的静态吸附和错流过滤过程中的动态沉积行为.实验考察了纳米镍悬浮液浓度、温度、时间、陶瓷膜孔径等操作条件对纳米镍吸附行为的影响,测定了纳米镍在膜面上的静态吸附和动态沉积数据.研究结果表明,纳米镍在膜表面的静态吸附符合Langmuir等温方程,纳米镍的吸附量随着时间和浓度的增加先迅速增加而后缓慢上升并趋于稳定;在错流过滤过程中,随着料液浓度,过滤时间的增加,纳米镍的沉积量迅速增加,导致膜通量降低.对平均粒径为60 nm的镍粉过滤,孔径为0.3～0.8 μm的陶瓷膜较为合适,此时膜面上镍的吸附量小,渗透通量高.     

过滤方式及压力对速率影响的研究

介绍了相关过滤方式的优缺点,自主建立了过滤实验流程,设计出相应的膜滤器,通过实验,研究了横向终端过滤、竖向终端过滤、横向错流过滤和竖向错流过滤及过滤压力对过滤速率的影响等。结果表明:采用竖向流动错流过滤方式膜过滤速率大于其它方式的过滤速率,衰减最为缓慢,且一段时间后,速率趋于一定值;压力增大可以提高竖向流动错流过滤速率,但也加快了膜污染,使膜速率衰减加快。     

湿化学法制备纳米陶瓷粉体中膜清洗工艺基础研究

以TiCl4水解法合成的TiO2超微粒子为对象, 进行无机陶瓷微滤膜清洗过滤研究.考察了操作压力、错流速率、浆料浓度等工艺参数的影响, 确立适合于超微粒子膜清洗过滤的工艺条件为0.1 MPa, 5 m*s-1.实验结果表明, 膜清洗过滤效率、操作方式以及产品质量等方面都明显优于目前工业生产上普遍应用的板框压滤机, 为无机陶瓷微滤膜技术应用于湿化学法合成超微粒子清洗过滤提供了科学与工程化依据.     

主动错流式膜分离设备的研制

针对传统膜分离设备易堵塞、清洗频繁、操作能耗高等缺陷,根据错流过滤原理,采用中空腔式膜组件、内置式集水系统和浸没式旋转结构等,自主研发了一种主动错流式膜分离设备。对原理验证样机的考察试验结果表明,该设备能够实现高效错流过滤、消除浓差极化、延缓膜污染、降低操作能耗,在水处理和工业分离领域具有推广应用前景。     

动态膜处理污水时阻力分布及污染机理

对高岭土动态膜处理污水过程中膜污染阻力分布及膜污染机理进行了研究。通过测定和计算得知不同操作条件下各部分阻力的比例及其变化情况。动态膜过滤污水的阻力主要由动态膜膜孔堵塞阻力和膜面污染层阻力所控制。随着错流速度的增大,总阻力减小,各部分阻力的比例有所变化,但动态膜膜孔堵塞阻力和膜面污染层阻力依然占主导地位。利用传统膜过滤时有关膜污染的堵塞模型和滤饼过滤模型对动态膜处理污水时的实验数据进行分析,结果表明,动态膜过滤污水过程中,过滤初期约10 min左右,污染以膜的微孔堵塞为主,此后,膜的污染情况因操作条件不同而有所差异,影响最显著因素为错流速度,当错流速度较小时,膜的污染以膜面沉积污染物为主,符合滤饼过滤模型。适当提高错流速度有利于减小过滤阻力。     

非均粒悬浮液的陶瓷膜错流深滤速度研究

根据使用陶瓷膜中存在的问题,并以非对称陶瓷膜结构特点为基础,提出了以陶瓷膜支撑层（深层）与膜层共同作为过滤介质的一种新的陶瓷膜错流深层过滤方式。用非均粒径高岭土悬浮液,经过自行设计的实验流程和错流过滤器,进行了陶瓷膜错流深层过滤等实验。对取得的实验数据进行分析对比,得到了在相同操作条件下新方式比传统错流膜过滤的过滤阻力...     

陶瓷膜构型对错流微滤酵母悬浮液性能的影响

采用3种构型的陶瓷微滤膜元件对酵母悬浮液进行错流过滤实验,考察陶瓷膜元件的构型对于其错流过滤性能的影响。结果表明:减小陶瓷膜元件的通道直径可以提高料液在膜表面的剪切力,有助于提高过滤稳定通量和临界压力,在3 m/s膜面流速、0.1 MPa跨膜压差条件下,单管、19通道、55通道的稳定通量分别为96、128、196 L/(m2.h);在3 m/s膜面流速条件下,3种陶瓷膜元件的临界压力分别约为0.15、0.2、0.2 MPa。另外,减小通道直径还可以减小滤饼层的比阻,有利于降低过滤阻力;与提高膜面流速来增大过滤通量的方法相比,减小陶瓷膜的通道直径具有能耗较小的优点。     

Sugar Purification from Enzymatic Rice Straw Hydrolysis Products using Cross-Flow Diafiltration

The sugars produced by enzymatic hydrolysis of rice straw are separated using cross-flow diafiltration in this study. The effects of membrane type, membrane pore size, cross-flow velocity and transmembrane pressure on the filtration flux, sugar rejection, and sugar mass flux transported to the filtrate are discussed. The filtration flux increases with increasing cross-flow velocity or transmembrane pressure. When the membrane made of mixed cellulose ester (MCE) is used, over 70% filtration resistances are caused by the membrane fouling; while the resistance due to virgin membrane is dominant when regenerated cellulose (RC) membranes are used. A force balance model is applied to relate the filtration flux and filtration resistance to operating conditions. The calculated data of filtration flux based on this model agree fairly well with experimental data. In addition, a theoretical model is used to explain the sugar transmission through the cake and membrane pores. The sugar rejection coefficient decreases with increasing cross-flow velocity because of the effect of cake reduction. This effect is more significant when the MCE membrane is used. Comparing the sugar mass flux transported into the filtrate, it is more effective for sugar purification by using 10 kD RC membrane and under higher transmembrane pressures.     

高黏度液体错流旋转微滤实验研究

Experimental investigation of the microfiltration （MF） using a revolving cross-flow membrane filter was performed under the condition of constant pressure difference, and different flat membranes made of polyvinylidene fluoride （PVDF, 0.1 μm）, cellulose acetate （CA, 0.22 μm）, sulfonated polyethersulfone （SPES, 0.22 μm） and polyamide （PA, 0.45 μm）, respectively, were used in filtration experiments. The dependence of the filtrate mass of the cross-flow MF on time was measured on-line. The experimental results showed that the effect of the cross-flow on high viscosity medium was more significant than that on the low viscosity one.     

混凝耦合多孔陶瓷膜净化河水简

Membrane filtration technology combined with coagulation is widely used to purify river water. In this study, micro filtration （MF） and ultrafiltration （UF） ceramic membranes were combined with coagulation to treat local river water located at Xinghua, Jiangsu province, China. The operation parameters, fouling mechanism and pilot-scale tests were investigated. The results show that the pore size of membrane has small effect on the pseudo-steady flux for dead-end filtration, and the increase of flux in MF process is more than that in UF process for cross-flow filtration with the same increase of cross-flow velocity. The membrane pore size has little influence on the water quality. The analysis on membrane fouling mechanism shows that the cake filtrationhas significant in fluence on the pseudo-steady flux and water quality for the membrane with pore size of 50, 200 and 500 nm. For the membrane with pore size of 200 nm and backwashing employed in our pilot study, a constant flux of 150 L-m^-2-h^-1 was reached during stable operation, with the removal efficiency of turbidity, total organic carbon （TOC） and UV254 higher than 99%, 45% and 48%, respectively. The study demonstrates that coagulation-porous ceramic membrane hybrid process is a reliable method for river water purification.     

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.     

Modeling of fouling layer deposition in cross-flow microfiltration during tomato juice clarification

The effect of parameters, such as transmembrane pressure and axial flow rate, on membrane fouling during tomato juice clarification were studied by cross-flow microfiltration using flat sheet polyvinylidenefluoride membranes. The effect of fouling on permeate flux was modeled using a classical constant pressure dead-end filtration equation and its modified form for cross-flow filtration. The main physico-chemical properties of tomato juice were evaluated. The clarified juice was very similar to the feed except for insoluble solids and lycopene, which were concentrated in the retentate. Cake formation was identified as the main reason for flux decline. At different axial flow rates, the fouling mechanism evolves from cake filtration to an intermediate pore blocking mechanism with increasing pressure.     

无机陶瓷膜澄清食醋工艺研究

为了除去老陈醋中的细菌和沉淀物,采用无机陶瓷膜对含有菌体和沉淀物的老陈醋进行过滤实验研究。通过研究无机陶瓷膜平均孔径、跨膜压差、膜面流速、操作温度、料液浓缩比、流动状态等操作条件对老陈醋过滤效果的影响,确定了适宜的工艺分离条件:膜孔径100 nm、室温(30℃以下)、跨膜压差0.14 MPa、雷诺数5 000、膜面流速2.0 m/s、最大浓缩倍数为9。在适宜的工艺分离条件下,平均通量可达40 L/(m2.h);过滤后食醋的理化和卫生指标均符合国家标准,且放置2年后无沉淀现象。因此,采用无机陶瓷膜澄清食醋在技术上是完全可行的方法。     

Cross-Flow Microfiltration of Bacillus Subtilis Broths under Various Culture Times

Bacillus subtilis broths under different culture times are filtered in a cross-flow microfilter. The operating condition effects, such as cross-flow velocity, transmembrane pressure, and broth culture time, on the filtration flux, cake properties, and extracellular polymeric substances (EPS) transmissions are discussed thoroughly. The culture broths contain B. subtilis cells and EPS which is characterized as polysaccharides (hydrocarbons) and proteins. An increase in broth culture time leads to higher concentrations of cells, soluble and extractable EPS. The total protein to polysaccharide concentration ratio in the broths is ca 0.2. However, the soluble polysaccharide concentration is 10-fold higher than that of soluble proteins. The filtration flux increases with increasing cross-flow velocity or transmembrane pressure. However, the impact of cross-flow velocity is more significant. The filter cake resistance formed by B. subtilis cells and EPS flocs plays the most important role in determining the overall filtration resistance. The mass and average specific filtration resistance of cake can be estimated using a force balance model and empirical equations. The cake structure and thickness are analyzed using SEM. A thicker and more compact cake may be formed under longer broth culture time. Most soluble polysaccharide and protein molecules have the opportunity to penetrate through the cake and membrane into the filtrate because the solute transmissions are measured as high as 0.75–1.0. The influences of operating conditions on the polysaccharide and protein transmissions are negligible. Therefore, to enhance filtration flux by increasing transmembrane pressure or cross-flow velocity is beneficial to improve separation efficiency, especially by increasing cross-flow velocity.     

Treatment of Oily Wastewaters Using the Microfiltration Process: Effect of Operating Parameters and Membrane Fouling Study

This work focuses on the treatment of oily wastewater using the cross-flow microfiltration (MF) process to determine the effect of different operating parameters such as transmembrane pressure (TMP) and cross-flow velocity on the separation performance and to study the mechanism of membrane fouling during microfiltration of oil in water emulsions. In this regard, the permeation flux and oil rejection of a polyvinylidene fluoride (PVDF) membrane in a flat-frame MF module for separation of 3000 ppm oil/water emulsions were measured. The results indicated that the permeate flux increased by an enhancement in both TMP and cross-flow velocity, while the oil rejection decreased. The analysis of variance (ANOVA) showed that the individual effect of TMP and cross-flow velocity is more important than the interactional effect of these operating parameters on the permeate flux and oil rejection. The results of fouling modeling revealed that the membrane fouling mechanism was affected by the applied TMP. The cake filtration model dominates the fouling mechanism at lower operating pressures. The fouling mechanism was changed from the cake formation to intermediate pore blocking and then to standard pore blocking as the TMP varied from 1 to 3 bar. Finally, a five-step procedure was used for cleaning the oil/water fouled membranes.