天然有机物和离子对纳滤膜过滤性能的影响研究

采用纳滤膜Desal 5 DK对天然有机物(NOM)和离子进行死端过滤实验,以考察进水组分对膜过滤性能的影响。结果表明,Desal 5 DK对NOM的截留率为60%~80%,由NOM引起的不可逆水通量降低占总水通量降低的70%。Desal 5 DK对水中Ca2+的截留率90%,而对Na+的截留率保持在20%~38%,离子与荷电纳滤膜之间的道南效应以及水合离子大小和扩散系数的不同引起二者截留率的差异,并导致了水通量衰减。     

纳滤处理燃机电厂清洗废液及膜污染研究

采用NF 90、NF 270、NF 2001、NF 5001 4种纳滤膜对燃机电厂压气机清洗废液进行处理,考察操作压力、初始COD_Cr、温度和pH等因素对纳滤膜性能的影响。结果表明,操作压力为0.7 MPa时,4种纳滤膜对废液中低分子质量的难生物降解溶解性有机物截留效果均较好,产水水质满足纳管标准(COD_Cr≤500 mg/L)。操作压力在一定范围内增加,4种纳滤膜膜通量和COD_Cr截留率呈不同幅度的上升趋势,压力由0.6 MPa增加至1.0 MPa时,NF2001产水COD_Cr降幅最大(70.73%),NF 5001膜通量增幅最大(28.14%)。初始COD_Cr增加使膜通量下降而对COD_Cr的截留效果提高,且随着温度由20℃升高至40℃,及pH由3升至10,各膜通量均有一定程度的提高。此外,较低温度(20℃)下NF 270膜通量较大且不可逆污染值较小,因而在处理压气机清洗废液中具有良好的应用前景。     

微滤/纳滤联用技术深度处理印染废水

采用微滤-纳滤联用装置对印染废水进行深度处理,考察了作为预处理的微滤技术对生化二沉池出水的COD和浊度的去除效果.进一步考察了纳滤膜的COD去除率、盐截留率和脱色效果,并考察了各种操作条件对渗透通量的影响.试验结果表明,经微滤一纳滤联用技术处理后的水质COD去除率大于86%,盐截留率大于95%,浊度和色度去除率高达100%.纳滤膜的渗透通量随着操作压力的增大而增大,并且在温度25～30℃之间有较高的渗透通量,其在较高的pH范围内渗透通量较高.该系统产水达到国家一级排放标准,并可以回用做工业用水,具有很好的工业应用价值.     

纳滤对高浓度冶炼废水处理的可行性研究

针对纳滤法处理高浓度实际冶炼废水,分别研究了压力、流量、温度、pH等因素对高、低浓度实际冶炼废水中金属离子截留率及膜通量的影响。结果表明,DL纳滤膜对高浓度废水在最佳条件下的膜通量及金属离子截留率都很高(RZn=96.8%,RCa=97.5%,RCd=89.7%)。纳滤处理高浓度冶炼废水在一定条件下是可行的,为冶炼废水的处理又提供了一条途径。     

电镀含锌废水的纳滤-反渗透处理回用研究

采用纳滤(NF)-反渗透(RO)组合工艺浓缩回收电镀含锌废水,研究了运行压力、进水含量、pH、水温对膜分离效果的影响.结果表明,NF-RO 1812膜对Zn2+具有良好的截留效果,产水电导率在25μS·cm-1 以下,产水Zn2+的质量浓度均低于0.7mg·L-1,累计回收率高达85.6%,可直接回用于镀件的清洗;浓缩液经RO二级浓缩后,Ze2+的质量浓度由454.8 mg·L-1 浓缩至1500 mg·L-1,可用于电镀槽液的配制.     

纳滤法去除中低放射性废水中钴离子的研究

研究纳滤法对模拟核电站中、低放射性水平废水中痕量Co2+的去除效果,采用NFW-2B平板聚酰胺纳滤复合膜,考察了压力、pH、无机离子干扰和投加有机络合剂等情况下对膜通量和Co2+去除率的影响。结果表明,随着压力的升高,膜通量增大,截留率在一定压力范围内先增大后降低;pH对膜通量影响不大,在25℃、pH=10附近时,截留效果最佳;在以聚丙烯酰胺作为络合剂的情况下,pH=7、装载量比为0.25时得到较好的去除效果,有效截留率达到98%以上。     

纳滤工艺深度处理焦化废水的中试研究

以焦化废水为研究对象,考察了取消超滤预处理系统后,纳滤处理系统对该类废水污染物的处理效果。结果表明:纳滤工艺可直接应用于焦化废水的深度处理,COD去除率稳定在70%以上,出水COD维持在45mg/L以下;对氨氮的去除率可达50%以上;对总硬度的脱除率达96%以上,出水硬度维持在3.5 mg/L左右,各项水质均优于循环冷却水要求。虽然单独纳滤工艺稳定运行周期相对双膜工艺较短,但两种工艺的污染差异可通过化学清洗加以消除。     

纳滤膜技术用于正己烷脱蜡的可行性探讨

淤浆聚乙烯技术生产过程中存在着溶剂脱蜡的问题。目前常用的溶剂脱蜡工艺为离心固液分离后蒸汽加热气化溶剂正己烷,但这种工艺会造成较大的能源消耗。为降低成本,提出了一种膜分离技术应用于淤浆聚乙烯中溶剂的脱蜡,并基于理论分析与实验证明了这种技术的可行性。结果表明,国产的聚酰胺(PA)复合膜和聚醚砜(PES)膜对石蜡实现了高截留率,分别为95.8%和96.4%。同时溶剂渗透通量分别为18.6和16.3L/(m2·h),并且,膜材料较好的长期操作稳定性和耐清洗能力,使膜分离技术在淤浆聚乙烯中溶剂脱蜡中的实际应用得到保证。     

聚合硫酸铁处理含氟废水的研究

采用自制的聚合硫酸铁(PFS)对一种含氟量较高的水样进行了实验条件下的混凝处理,讨论了在搅拌速度和初始pH不变的情况下,PFS用量及絮凝时间对除氟效果的影响,找出了最适宜处理条件。结果表明:该含氟废水用PFS处理可以收到良好的除氟效果;室温下混凝处理的最适宜条件是:pH=7.0,絮凝时间为30～40 min,PFS用量为1.75 mL·L-1。     

钙盐-电凝聚法处理含氟工业废水

对钙盐-电凝聚法处理含氟工业废水的影响因素和效果进行了试验和分析。试验结果表明,钙盐-电凝聚法处理含氟工业废水的最佳反应条件为:n(Ca2+)/n(F-)为1～2,电流密度为1～5mA/cm2,电解时间t为10min,pH值为6～9,投加的钙盐以CaCl2最佳。现场试验钙盐-电凝聚法处理含氟工业废水比传统药剂混凝好,出水能够达到国家排放标准。     

超滤膜处理含聚合物采油废水的实验研究

经过常规沉降和砂滤工艺处理后的采油废水,因其含油量、悬浮物和浊度过高而无法达到配制聚合物的用水标准.为了使含油废水符合配制聚合物的用水要求,采用聚偏氟乙烯超滤膜对大庆油田含油废水进行处理,结果表明,膜滤出水的油和悬浮物质量浓度均小于1.0 mg/L,去除率可达到95%,浊度低于1.0 NTU,去除率达到90%以上.同时对膜的清洗进行了实验,用自制以十二烷基苯磺酸钠为主的清洗药剂对膜进行清洗,能使膜通量基本恢复,有效延长了膜的使用寿命.     

一种新型NF膜在含镍废水回用中的应用

试验采用TFC(R)-S型纳滤(NF)膜,研究含镍废水回用工艺.讨论了试验温度、操作压力、进料流率和溶液中Ni2 的质量浓度对Ni2 的质量截留率和透过流率的影响.料液中Ni2 的质量浓度由30 mg/L,经过处理浓缩至17.7 g/L,浓液达到直接回用于镀槽的要求,99%的透过液可以达到回用标准,并且回收了约99%镍.采用NF膜处理含镍废水具有流程简单、投资小、操作费用低、物料分配合理等特点,适用于工业应用.     

气液两相流强化卷式纳滤膜分离硫酸镁水溶液

气液两相流强化卷式纳滤膜分离实验是针对DK2540卷式纳滤膜,采用气液两相流强化分离技术,对硫酸镁溶液进行研究,较系统地研究了温度、料液浓度、过膜压力、料液流速、气体流速等因素在分离硫酸镁溶液时,对膜通量、截留率和膜通量增加率的影响,并总结了气液两相流强化效果。结果表明,气液两相流强化卷式纳滤膜分离有明显的效果。温度宜在30~40℃。料液浓度越大、过膜压力越小、气液比越大,气液两相流强化效果越明显。     

Sugars and Fructans Separation by Nanofiltration from Model Sugar Solution and Comparative Study with Natural Agave Juice

The fructan separation from a model sugar solution and natural agave juice was studied using a stirred-cell nanofiltration unit operated in concentration mode. Hydrophilic cellulose membrane with MWCO of 1000 Da was used. The experimental conditions were varied to predict the influence of pressure (0.14–0.350 MPa) and feed concentration (0.15–0.25 g/mL) on the initial permeate flux and solute retained fraction (SRF) values of the process. Response surface plots (p < 0.05) showed that the permeate flux and SRF increased significantly with the pressure and decreased with feed concentration. The permeate flux varied from 0.5 to 4.1 L · h^?1 · m^?2. The fructan retained fraction in model sugar solution varied from 0.85 to 0.97 whereas fructose, glucose and sucrose presented similar SRF values ranging from 0.38 to 0.65. Promising results were obtained when natural agave juice was used.     

Multicomponent Steady State Modeling of Concentration Polarization Including Adsorption during Nanofiltration of a Textile Effluent

Steady state modeling of nanofiltration of a textile effluent was carried out. The model comprised of three distinct parts. Film theory was used to account for the solute transport outside the membrane surface within the mass transfer boundary layer. An osmotic pressure model and a solution-diffusion model were used to quantify the solvent and solute flux through the porous membrane. The osmotic pressure model was modified by incorporating adsorption of dyes onto the membrane surface. The system had three components, namely, Cibacron Black and Cibacron Red and the salt as sodium chloride. The model had three parameters, namely, solute permeability of two dyes and sodium chloride through the membrane. These parameters were estimated by comparing the calculated and experimental data of permeate flux and permeate concentration. It was observed that membrane hydraulic resistance and the resistance due to concentration boundary layer were more significant. The calculated permeate flux was within ±20% of the experimental data. Values of resistance due to adsorption of dyes onto the membrane surface were calculated to be about 2 to 3% of total resistance and of those due to concentration boundary layer were about 47%.     

过磷酸钙含氟废水处理装置的工艺改进

针对含氟废水处理装置试运行过程中中和反应效果不佳、污水沉降时间不足等问题,采用机械搅拌强化中和反应,并投加絮凝剂提高沉降效率,确保了废水达标排放。     

陶瓷纳滤膜处理淋浴污水及膜的清洗

采用无机陶瓷纳滤膜对淋浴污水进行分离特性试验,重点探讨了膜通量随时间的衰减情况以及操作压差、污水温度和pH值等操作参数对淋浴污水处理效果和膜通量的影响;并就陶瓷膜的污染对膜的清洗方法进行了初步研究。研究结果表明,陶瓷纳滤膜对淋浴污水中COD、TOC和浊度均有一定的去除效果,用水洗＋碱洗＋酸洗的综合清洗方法可以获得较好的清洗效果     

Modeling hydrogen fluoride adsorption by sodium fluoride

In the current study, hydrogen fluoride (HF) adsorption onto the sodium fluoride pellets is modeled. For this purpose a two-dimensional, non-isothermal model was developed and the governing equations were solved numerically. The contributions of diffusion transport in axial and radial directions also were considered in mathematical formulations. The model results of effluent concentration and breakthrough curves of HF were compared with the experimental data obtained in a lab-scale adsorption unit, reported in our previous work [1]. The results indicate while the feed gas velocity decreases, the HF adsorption capacity on NaF is significantly enhanced and there is a delay in breakthrough time. The adsorption capacity of HF on NaF decreases slightly when inlet HF concentration increases. Moreover, the model results were compared with the obtained results from a one-dimension model. This comparison indicates that one-dimensional model can well predict the HF dynamic adsorption behavior for lab-scale fixed beds. Comparing the experimental breakthrough curves of HF adsorption on NaF pellets with the model results shows the ability and accuracy of the model with maximum 7.82% errors.     

Modeling of Nanofiltration of Dye Using a Coupled Concentration Polarization and Pore Flow Model

Concentration polarization and transport through pores are used to explain the permeation of eosin dye through a nanofiltration membrane. Due to the ionic character of the dye, fixed charges in the membrane pores affect the permeation of the dye. Two transport coefficients, namely, hindered coefficients for diffusion and convection, steric hindrance factor of dye, and pore charge density are estimated by minimizing the error involved between the experimental and calculated permeate flux and concentration values. Contributions of electrical migration, convection, and diffusion towards the solute flux, have been quantified. It is found that more negative fixed charges on membrane pores leads to reduced dye concentration in the permeate.