纳滤膜及其在水处理中的应用

纳滤膜具有筛分效应和电荷效应两个显著特性,能截留大分子量有机物和多价离子,而允许小分子有机物和单价离子通过。对于纳滤膜的分离机理,提出了非平衡热力学模型,电荷模型,静电排斥和立体位阻模型。根据纳滤膜特有的性质,介绍了其在水处理领域包括水的软化、脱除饮用水中有害物质、废水处理三个方面的应用,并分析了纳滤膜污染的机理以及防止措施。     

纳滤膜分离技术处理饮用水研究进展

综述了纳滤膜分离技术及其在饮用水处理中的应用。研究发现,纳滤膜分离技术在含有多种复杂有毒有害污染物的饮用水处理中可发挥重要作用,可以高效去除饮用水中的有机物、无机物、重金属离子、微量污染物等有害物质。膜分离技术的去除污染物机理一般为筛分作用及电荷效应。纳滤膜在去除饮用水中有毒有害物质有良好的作用效果,突破纳滤膜制备成本、使用寿命瓶颈的膜分离技术对相应物质浓缩富集效能的提升具有重要意义。     

纳滤膜分离技术处理饮用水研究进展

综述了纳滤膜分离技术及其在饮用水处理中的应用。研究发现,纳滤膜分离技术在含有多种复杂有毒有害污染物的饮用水处理中可发挥重要作用,可以高效去除饮用水中的有机物、无机物、重金属离子、微量污染物等有害物质。膜分离技术的去除污染物机理一般为筛分作用及电荷效应。纳滤膜在去除饮用水中有毒有害物质有良好的作用效果,突破纳滤膜制备成本、使用寿命瓶颈的膜分离技术对相应物质浓缩富集效能的提升具有重要意义。     

纳滤膜对邻苯二甲酸酯的动态吸附行为及截留特性

采用NF270纳滤膜进行饮用水中微量邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸正二丁酯( DnBP)和苯二甲酸异二丁酯(DiBP)等4种邻苯二甲酸酯(PAEs)去除的试验研究,分析了NF270纳滤膜对PAEs的吸附动力学行为,考察了PAEs的辛醇/水分配系数和分子量对其NF270纳滤膜吸附性能和截留特性的影响.结果表明,Freundlich吸附方程能较好地描述NF270纳滤膜对PAEs的动态吸附行为;在饮用水中微量PAEs去除过程中,NF270纳滤膜对DMP、DEP、DnBP和DiBP的截留特性开始表现为膜面吸附作用和膜孔筛分效应,吸附达到平衡后截留机理取决于膜孔的筛分效应,此时DMP、DEP、DnBP、DiBP的截留率分别为44％、68％、92％、93％(0.5 MPa,30℃,PAEs质量浓度为100 μg·L-1),表明NF270纳滤膜能高效截留饮用水中的DnBP、DiBP.     

饮用水中消毒副产物的形成机理与控制技术研究

饮用水中消毒副产物的主要存在形式为三卤甲烷类和卤乙酸类有机物。对饮用水中消毒物产物 的形成机理及目前控制饮用水中消毒副产物的方法和特点进行了论述。     

二级处理水中溶解性有机物特征及其对纳滤膜性能的影响

本试验采用分子量分级膜和XAD-8树脂,分析了城市二级处理水的溶解性有机物分子量和亲疏性分布特征及其对纳滤膜性能的影响.结果表明,城市污水厂二级出水水中的溶解性有机物主要集中在<2 kDa的分子量区间上,且疏水性有机物的含量比亲水性有机物的含量大;分子量区间分布不同的有机物对纳滤膜透水通量和截留率有着不同的影响,分子量2 kDa以下的有机物引起纳滤膜透水通量衰减较大,有机物截留率较小,达57.2%;分子量10～100 kDa的有机物引起纳滤膜透水通量衰减较平缓,有机物截留率却较大最高达73.8%;亲疏性不同的有机物对纳滤膜透水通量和截留率有着不同的影响,经对膜表面阻力的测定,证实引起膜透水通量和截留率变化的主要物质为疏水性物质,而亲水性物质引起的变化较小.     

纳滤膜特性及对水中微污染物的控制

随着膜技术的发展与应用,20世纪80年代出现的纳滤膜充分弥补了反渗透与超滤之间的空白。介绍了纳滤膜的特性及其独特分离特点,阐述了纳滤膜在处理饮用水中有机污染物的必要性和合理性。最后指出了它的应用前景。     

CNT改性聚砜复合纳滤膜去除水中微量PAEs的研究

采用经CNT(碳纳米管)改性的纳滤膜处理水中微量邻苯二甲酸酯类(PAEs),研究各种因素对纳滤膜截留PAEs行为的影响。结果表明,经CNT改性的纳滤膜能有效去除PAEs,其截留率在84%以上。纳滤膜对PAEs的通量随操作压力、温度和p H的增大而增加,随离子强度的增大而减小;对PAEs的截留率随操作压力和离子强度的增大而增大,随温度的增大而减小,随p H的增大先增大后减小。     

CNT改性聚砜复合纳滤膜去除水中微量PAEs的研究

采用经CNT(碳纳米管)改性的纳滤膜处理水中微量邻苯二甲酸酯类(PAEs),研究各种因素对纳滤膜截留PAEs行为的影响。结果表明,经CNT改性的纳滤膜能有效去除PAEs,其截留率在84%以上。纳滤膜对PAEs的通量随操作压力、温度和p H的增大而增加,随离子强度的增大而减小;对PAEs的截留率随操作压力和离子强度的增大而增大,随温度的增大而减小,随p H的增大先增大后减小。     

纳滤膜在直饮水终端系统中的应用

为获得优质饮用水,以市政自来水为原水,对以纳滤膜为核心的直饮水终端对自来水中各种杂质的去除效果以及产水的经济性进行研究。结果表明,以纳滤膜为核心的直饮水终端系统对去除饮用水中浊度、硬度、TDS、硫酸盐、氯化物以及氟化物等均具有较好的效果,且均能达到饮用净水水质标准(CJ 94-2005)的要求;出水水质口感良好,安全性高;系统产水成本低更具有经济性,适合推广使用。     

Transformation in Bulk and Trace Organics during Ozonation of Wastewater

The aim of this paper is to determine the ozone dosages needed to oxidize bulk and trace organics. Treated effluent from eight full-scale wastewater treatment plants was collected and subjected to lab-scale ozonation. Because both organics and inorganics exert ozone demand, an approach was developed to calculate only the ozone demand associated with organics. This method allowed normalization of dosing parameters to correlate with removal of color, UV absorbance, plus oxidation of trace organics and nitrosamine precursors. We also showed that ozonation effectively reduces the fraction of organic matter characterized as “colloidal organic matter,” thereby reducing the potential for membrane fouling.     

有机中微肥的生产及其应用前景

我国中低产田面积占总耕地面积70%以上,其中大部分存在有机质和中微量元素缺乏和肥料利用率低的问题。为防止中微量元素施入土壤后被固定而失效,提出利用废弃资源,生产有机中微肥(如氨基酸、木质素磺酸、腐植酸中微肥等),其生产成本比EDTA螯合中微肥低,并简要介绍了各种有机中微肥的生产工艺过程。只要做到测土施肥,有针对性加入有机中微肥,即可达到提高作物产量、品质,提高肥料利用率,提高土壤肥力的良好效果。     

渗透汽化技术在液体分离中的研究新进展

渗透汽化是近年膜科学研究中最活跃的领域之一,在分离液体混合物,尤其是痕量、微量物质的移除,近、共沸物质的分离等方面有独特优势。简要介绍了渗透汽化技术的历史及发展过程,着重介绍了近几年渗透汽化技术在液体分离方面的研究进展。从研究结果来看,从水溶液中分离有机物研究主要集中在醇、酯的分离。在有机物脱水方面,开发出了选择性更好、渗透量更高的膜,乙醇脱水也有不少新的研究成果。特别是在有机混合物分离方面,取得了长足的进展,可以分离更多的有机物。     

Poly(Trimethylsilylpropyne) Utility as a Polymeric Absorbent for Removal of Trace Organics from Air and Water Sources

Abstract

Poly(trimethylsilylpropyne), PTMSP, is well known to exhibit the highest permeability for gas and vapors of all dense polymeric systems. The high free volume observed yields extremely high diffusion coefficients for penetrating species. These properties have yielded interest for various gas and pervaporation membrane separation processes. It has been found that PTMSP also exhibits unique characteristics as a polymeric absorbent for removal of trace organics from air and water sources. The distribution coefficient for organics between the PTMSP phase and the water phase is extremely high for aliphatic, aromatic, and chlorinated hydrocarbons. In fact, PTMSP approaches activated carbon adsorbents in efficiency (much closer than other polymeric species). The removal of organics from PTMSP proceeds easier than activated carbon, and applications involving simple regeneration of a fixed bed may indeed be possible.     

水中痕量有机物光催化降解初始速率排序和预测

TiO2光催化技术消除饮用水中痕量有毒有机物的实际应用不像实验室基础研究一样有令人满意的进展，理论研究体系的相对简单与实际应用体系复杂多变的矛盾是现阶段存在的主要问题之一。通过有机物聚类分析将现有的有机物降解实验数据进行归类和排序;同时，从有机物初始浓度与初始降解速率的关系出发，通过Freundlich动力学方程，用研究成熟、检测方便的常量和微量浓度区域的实验数据来预测痕量和超痕量浓度范围内的降解速率，而这个浓度范围正是饮用水深度净化过程所必须涉及的。两方面的结合为理论研究体系与实际应用体系的衔接探索了一条新的思路。     

石墨烯基气凝胶对有机物的饱和吸附能力

以Pickering乳液法进行了石墨烯基气凝胶(GA)的制备,并以纯有机物和水中乳化油分为吸附对象,对其饱和吸附能力进行了评价,综合对比了不同研究者利用碳纳米材料所制备碳基气凝胶对纯有机化合物的吸附能力,发现包含本文所制备的GA在内的各种碳基气凝胶对不同的有机物的吸附能力与有机物的密度成正比,表明单位质量碳基气凝胶吸附有机物的体积(cm³?g^?1)为定值,与具体的被吸附有机物的种类无关。推断有机物在气凝胶材料中的吸附是一种体积填充行为,气凝胶孔隙体积的大小对于其吸附有机物的能力具有重要影响,但孔隙的占有率也是决定实际吸附有机物能力的关键因素。所制备的GA对水中油分的吸附能力低于其对纯油分的吸附能力,应与水的竞争吸附、有机物的扩散阻力等有关。     

组合介质对梅梁湾水源水中有机物的去除工艺特性

本文对利用组合介质富集湖水中的土著微生物去除太湖梅梁湾水源地水体中有机污染物进行了试验研究。中试结果表明：随着介质密度和水力停留时间的增加，对有机物的去除率都有所增大。介质密度为26．8％、水力停留时问为5d时，组合介质对TOC、DOC、AOC、CODMn的去除率分别为38．5％、13．7％、17．2％、39．4％。水流速度增加并未降低对有机物的去除效果，生物降解是去除水源水中有机物的主要途径。通过人工介质富集微生物的方法对太湖梅梁湾水源地水体中有机物有较好的去除效果。     

饮用水深度处理系统溶解性有机物的变化与组成特性

采用混凝、沉淀、砂滤联合臭氧、生物活性炭构建饮用水深度处理系统,以黄浦江原水为研究对象,研究该系统对各类有机物的去除效能,探讨溶解性有机物在系统中的变化与组成特性。结果表明：黄浦江原水中以分子量小于3000的有机物为主,占总溶解性有机物的55.9%;常规单元、臭氧、生物活性炭对溶解性有机物的去除有功能互补性,常规单元对分子量大于10000的有机物去除率达61.1%,而对分子量小于3000的DOC去除率仅为7.9%,臭氧氧化可使难降解有机物改性为小分子量有机物,经生物活性炭单元后,分子量小于3000的DOC去除率达到28.9%;微量有机物主要通过臭氧、生物活性炭单元被去除,生物活性炭单元出水中微量有机物种类降低至30种,浓度降低67.4%,三氯甲烷生成势去除率为相似文献   

An Intensive Study of the Size and Composition of Submicron Atmospheric Aerosols at a Rural Site in Ontario,Canada

Atmospheric sampling was conducted at a rural site near Egbert, about 70 km north of Toronto, Ontario, Canada from March 27 to May 8, 2003 to characterize the physical and chemical properties of the ambient aerosol in near real-time. The instrumentation included a tapered element oscillating microbalance (TEOM), an ultrafine condensation particle counter (UCPC), a scanning mobility particle sizer (SMPS), an aerodynamic particle sizer (APS), an aerosol mass spectrometer (AMS), and a particulate nitrate monitor (R&P 8400N) for aerosol measurements. Gas-phase non-methane hydrocarbon compounds (NMHCs) were measured by gas chromatograph-flame ionization detection (GC-FID). Filter samples were also collected for analysis of inorganic ions by ion chromatography (IC). Aerosol properties varied considerably depending upon meteorological conditions and airmass histories. For example, urban and industrial emissions advected from the south strongly influenced the site occasionally, resulting in higher particulate mass with the higher fractions of nitrate and organics. Cleaner northwesterly winds carried aerosols with relatively higher fractions of organics and sulfate. The AMS derived mass size distributions showed that the inorganic species in the particles with vacuum aerodynamic diameters between about 60 nm and 600 nm had mass modal vacuum aerodynamic diameters around 400–500 nm. The particulate organics often exhibited two modes at about 100 nm and 425 nm, more noticeable during fresh pollution events. The small organic mode was well correlated with gas-phase nonmethane hydrocarbons such as ethylbenzene, toluene, and propene, suggesting that the likely sources of small organic particles were combustion related emissions. The particulate nitrate exhibited a diurnal variation with higher concentrations during dark hours and minima in the afternoon. Particulate sulfate and organics showed evidence of photochemical processing with higher levels of sulfate and oxygenated organics in the afternoon. Reasonable agreement among all of the co-located measurements is found, provided the upper size limit of the AMS is considered.     

Applicability of Ozone and Biological Activated Carbon for Potable Reuse

The Upper San Gabriel Valley Municipal Water District in California is considering groundwater replenishment as a potential strategy to augment its potable water supply. This case study demonstrates the broad applicability of ozone and biological activated carbon (BAC) for such potable reuse systems based on recently developed criteria and models for bulk organics, trace organic contaminants, disinfection byproducts, and cost. Using an advanced treatment train composed of ozone (ozone to total organic carbon ratio of 1.0) and BAC (empty bed contact time of 20 min), a 10 million gallon per day potable reuse facility can achieve savings of $25–$51 million in capital costs, $2–$4 million per year in operations and maintenance costs, and 4–8 GWh per year in energy consumption in comparison to alternative treatment trains with reverse osmosis. This ozone-based treatment train is also capable of achieving public health criteria recently developed by the California Department of Public Health and the National Water Research Institute for potable reuse applications.