微絮凝-砂滤-超滤处理淮河原水的试验研究

采用微絮凝-砂滤-超滤工艺对淮河原水进行了中试规模的试验．重点考察预处理条件如滤速和混凝剂投加量的变化对后续膜处理性能的影响．结果表明，试验工艺去除CODMn的效果随着混凝剂投加量的增加而提高．在投加量(大于4mg／L)不变的条件下，滤速的变化不会影响砂滤出水的浊度和CODMn，当投加量为4mg／L时，较高的滤速导致砂滤出水的浊度和CODMn的增加．由于后续超滤膜的截留作用，膜出水的浊度和CODMn令人满意．     

粉末活性炭导入超滤系统去除水中天然有机物的性能研究

通过对比研究单独超滤系统和粉末活性炭导入超滤膜系统(PAC leading-in UF)发现,投加PAC后通量下降趋势有所减缓,但并不能显著地减缓膜污染并获得高通量,说明PAC吸附的溶解性小分子有机物不是造成膜污染的主要因素,而是在膜表面形成了"次级膜".试验中发现导入系统可显著提高对天然水中腐殖酸的去除效果,去除率可达到94%.此外在导入系统投加钙盐后可明显改善膜污染,达到有效控制膜通量的下降趋势的目的.     

美开发成功去除水中砷的新技术

据海外媒体报道，美国赖斯大学生物与环境纳米技术中心（CBEN）开发了二种去除水中有毒物质砷的技术。这项技术的诞生得益于一项关于铁锈颗粒将有磁相互作用的发现。     

饮用水超滤、纳滤技术应用及前景分析

本文将对膜技术中超滤和纳滤的特点及二者在饮用水处理中的具体应用展开分析,并展望超滤和纳滤未来的发展前景。     

氢化物发生-原子吸收法测定水中砷

本文采用氢化物发生-原子吸收法测定环境水样中砷的含量,最低检出限为0.20μg/l,对不同的水样进行测定,回收率在97.6％～103.0％之间。方法灵敏度高,基体干扰少,操作简便,易推广。     

壳聚糖在水处理中的应用进展

壳聚糖及其衍生物具有其它人工合成絮凝剂无法比拟的安全无毒、对环境友好等诸多优点,可以去除水中颗粒状和溶解性污染物,在水处理中有着广泛的应用。天然高分子聚合物壳聚糖可以处理含重金属离子的工业废水,还可以用于纺织、食品加工、炼油废水的絮凝处理,环境效益显著。对国内外近年来壳聚糖及其衍生物作为絮凝剂和吸附剂在水处理中的应用进行了综述,并探讨了壳聚糖作为绿色水处理剂的未来发展方向。     

壳聚糖及其衍生物的絮凝性、螯合性及抑菌性在水处理中的研究进展

天然高分子壳聚糖及其衍生物具有无毒、易生物降解、无二次污染以及良好的生物相容性等优点,在食品、医药、化工、农业等众多领域具有极高的应用价值。综述了壳聚糖及其衍生物的絮凝性,螯合性及抑菌性在水处理方面的研究进展,为其在水处理中的实际应用提供参考与借鉴。     

氢化物发生-原子荧光光谱法测定炉渣中微量砷

研究了氢化物发生-原子荧光光谱法对微量砷的测定,方法灵敏度高,准确度好。在最佳条件下,荧光强度与砷浓度4×10-4～0.20μg·ml-1范围内呈线性关系,检出限达1×10-4μg·ml-1。用此法测定了炉渣中微量砷,结果满意。     

原子荧光光谱法测定蔬菜中微量砷

采用混酸消解样品,通过探讨消化剂、盐酸浓度、硼氢化钾浓度对测定砷的影响,优化实验条件建立了氢化物发生原子荧光法测定中蔬菜微量砷的含量。该方法灵敏简便、快速准确。砷的检出限为0.047μg/L,线性范围0～80μg/L:样品分析结果的相对标准偏差为3.78%,回收率为94.8%～105.2%。     

改性壳聚糖复合材料在水处理中的研究进展

介绍了壳聚糖的分子特点、絮凝机理以及在水处理方面的优势,重点综述了壳聚糖分子与硅酸盐矿石、纳米磁性材料的复合改性以及壳聚糖分子交联、接枝的官能团改性在水处理方面的综合研究进展,提出了未来的发展应结合我国水质的具体特点,寻找更高效、环保的壳聚糖改性水处理剂,并早日实现工业化发展。     

Removal of arsenic from water by zero-valent iron

Batch and column experiments were conducted to investigate the effect of dissolved oxygen (DO) and pH on arsenic removal with zero-valent iron [Fe(0)]. Arsenic removal was dramatically affected by the DO content and the pH of the solution. Under oxic conditions, arsenate [As(V)] removal by Fe(0) filings was faster than arsenite [As(III)]. Greater than 99.8% of the As(V) was removed whereas 82.6% of the As(III) was removed at pH 6 after 9h of mixing. When the solution was purged with nitrogen gas to remove DO, less than 10% of the As(III) and As(V) was removed. High DO content and low solution pH also increased the rate of iron corrosion. The removal of arsenic by Fe(0) was attributed to adsorption by iron hydroxides generated from the oxic corrosion of Fe(0). The column results indicated that a filtration system consisting of an iron column and a sand filter could be used for treatment of arsenic in drinking water.     

胶团强化超滤处理含镉废水

采用聚砜中空纤维超滤膜,十二烷基硫酸钠为表面活性剂,对含镉废水进行胶团强化超滤．研究了运行时间、十二烷基硫酸钠(SDS)浓度、膜操作压力、溶液pH、溶液中电解质浓度、与非离子表面活性剂Brij复配等因素对该工艺的影响．结果表明,该工艺对镉的去除率可达99％以上．但该工艺不适用于强酸性废水,电解质的存在会降低截留率,SDS与Brij复配能提高截留率．     

Removal of arsenic from water using Fe-exchanged natural zeolite

An elevated arsenic (As) content in groundwater imposes a great threat to people worldwide. Thus, developing new and cost-effective methods to remove As from groundwater and drinking water becomes a priority. Using iron/aluminum hydroxide to remove As from water is a proven technology. However, separation of As-bearing fine particles from treated water presented a challenge. An alternative method was to use coarse-grained sorbents to increase the flow rate and throughput. In this research, a natural zeolite (clinoptilolite) was exchanged with iron(III) to enhance its As removal. Batch test results showed a Fe(III) sorption capacity of 144 mmol/kg on the zeolite. The As sorption on the Fe-exchanged zeolite (Fe-eZ) could reach up to 100mg/kg. Columns packed with Fe-eZ were tested for As removal from water collected from acid mine drainage (AMD) and groundwater containing high natural organic matter and high As(III). With an initial concentration of 147 μg/L in the AMD water, a complete As removal was achieved up to 40 pore volumes. However, the Fe-eZ was not effective to remove As from Chia-Nan Plain groundwater due to its high initial As concentration (511 μg/L), high amounts of natural organic matter, as well as its low oxidation-reduction potential, under which the As was in reduced As(III) form.     

Removal of chromium ions from aqueous solutions by polymer-enhanced ultrafiltration

This study deals with the removal of chromium species from aqueous dilute solutions using polymer-enhanced ultrafiltration (PEUF) process. Three water soluble polymers, namely chitosan, polyethyleneimine (PEI) and pectin were selected for this study. The ultrafiltration studies were carried out using a laboratory scale ultrafiltration system equipped with 500,000 MWCO polysulfone hollow fiber membrane. The effects of pH and polymer composition on rejection coefficient and permeate flux at constant pressure have been investigated. For Cr(III), high rejections approaching 100% were obtained at pH higher than 7 for the three tested polymers. With chitosan and pectin, Cr(VI) retention showed a slight increase with solution pH and did not exceed a value of 50%. An interesting result was obtained with PEI. The retention of Cr(VI) approached 100% at low pH and decreased when the pH was increased. This behavior is opposite to what one can expect in the polymer-enhanced ultrafiltration of heavy metals. Furthermore, the concentration of polymer was found to have little effect on rejection. Permeate flux remained almost constant around 25% of pure water flux.     

Removal of arsenic from water streams: an overview of available techniques

Arsenic poisoning has become one of the major environmental worries worldwide, as millions of people, which have been exposed to high arsenic concentrations (through contaminated drinking water), developed severe health problems. The high toxicity of this element made necessary the enforcement of stringent maximum allowable limits in drinking water. So, the development of novel techniques for its removal from aqueous streams is a very important issue. This paper offers an overview of geochemistry, distribution, sources, toxicity, regulations and applications of selected techniques for arsenic removal. The contribution briefly summarizes adsorption processes and mechanism of arsenic species removal from water streams by means of iron oxide/oxyhydroxide based materials. Sorption capacities of various sorbents (e.g. akaganeite, goethite, hydrous ferric oxide, iron oxide coated sand, Fe(III) loaded resin, granular ferric hydroxide, Ce(IV) doped iron oxide, natural iron ores, iron oxide coated cement, magnetically modified zeolite, Fe-hydroxide coated alumina) have been compared.     

Removal characteristics of anionic metals by micellar-enhanced ultrafiltration

Surfactant-based separation of Fe(CN)(6)(3-) and CrO(4)(2-) using regenerated cellulose membrane was studied in order to assess the potential of micellar-enhanced ultrafiltration for the remediation of wastewater or groundwater polluted with ferriccyanide and chromate. In the ferriccyanide/octadecylamine acetate (ODA) and chromate/ODA systems, removal of ferriccyanide increased from 73 to 92% and to 98%, and that of chromate from 64 to 97% and to >99.9% as the molar ratio of ODA to ferriccyanide and to chromate increased from 1 to 2 and to 3, respectively. In the ferriccyanide/chromate/ODA system, while the removal of ferriccyanide increased from 62 to 72% and to 93%, the removal of chromate from 20 to 38% and to 68% as the molar ratio of ferriccyanide:chromate:ODA increased from 1:1:1 to 1:1:2 and to 1:1:4, respectively. With the molar ratio of 1:1:6, the removal was >99.9 and 98% for chromate and ferriccyanide, respectively. Ferriccyanide ions were more easily bound to ODA micelles because the binding power of ferriccyanide was greater than that of chromate.     

Removal of arsenic from lead smelter speiss

The removal of arsenic from lead smelter speiss by volatilization techniques has been investigated. Elemental arsenic removal greater than 98 percent has been achieved by treatment of speiss and a sulfur source in a carbon monoxide atmosphere.     

Removal of arsenic from water using granular ferric hydroxide: macroscopic and microscopic studies

Removal of arsenate from water using granular ferric hydroxide (GFH) was investigated under different pH and As(V) loading conditions, using batch equilibrium adsorption, FTIR, and EXAFS methods. The arsenate adsorption envelopes on GFH exhibited broad adsorption maxima when the initial As(V) concentration was less than 500 mg/L at sorbent concentration of 10 g/L. As the initial As(V) concentration increased to 500, 1000 or 2000 mg/L for the same sorbent concentration, distinct adsorption maxima appeared and shifted to lower pH. Acidimetric-alkalimetric titration and arsenic adsorption isotherm data indicated that the surface of GFH is high heterogeneous. FTIR spectra revealed that complexes of two different structures, bidentate and monodentate, were formed upon the adsorption of arsenate on GFH, and bidentate complexes were only observed at pH values greater than 6. The EXAFS analyses confirmed that arsenate form bidentate binuclear complexes with GFH at pH 7.4 as evidenced by an average Fe-As(V) bond distance of 3.32 A.