国家饮用水标准与砷、镉去除技术

随着饮用水水质标准的进一步提高，对饮用水水体中的砷、镉最高浓度值也相应作出了严格的限制。常规给水工艺已经不能满足有效去除砷、镉的要求，因此必须采取安全、有效的方法，最大程度地降低砷、镉的危害，以保障饮用水的安全。笔者对国内外去除砷、镉的多种技术进行了分析，找出了去除饮用水中砷、镉的有效技术方法，以及时适应日益提高的饮用水标准要求。     

英德联合开发饮用水脱砷工业装置

欧盟曾于 1998年规定 ,饮用水中砷限值为 10 μg/ L,美国将于 2 0 0 5年实施类似标准。欧盟国家中 ,德国等已达到该限值。各国正在不断推崇低费用除砷工艺装置。英国于 2 0 0 1年秋有 2套装置投入运用 ,系由 Severn Trent公司与德国 Bayer公司合作开发 ,采用粒径为 0 .5～ 2 mm氧化铁颗粒固定床吸附水中的砷 ,吸附效果优于活性炭和活性氧化铝 ,也避免了离子交换树脂定期再生昂贵的费用支出。英德联合开发饮用水脱砷工业装置@未名     

原子荧光光谱法同时测定饮用水中的砷和硒

根据AFS-230双道原子荧光光度计测定原理和方法,同时用以测定饮用水中的砷和硒,结果表明：方法线性关系良好,砷、硒均为0-10μg/L,检出限：砷为0.08μg/L,硒为0.07μg/L。相对标准偏差：砷为1.41%,硒为1.06%。平均加标回收率：砷为96.2%,硒为94.3%。方法操作简便、灵敏度高、快捷、便于推广,适用于水中砷和硒的测定。     

砷的价态分析 水中三价砷和总砷的测定(硼氢化钾—二乙氨基二硫代甲酸银分光光度法)

简介了解砷离子在水中存在的价态,既有利于判别和确定砷的污染源,又可间接了解水中某些微生物的活动对水的氧化还原特性的影响。因此,近年来,除测定水中总砷外,尚需对砷存在的价态进行分析     

纳滤膜技术在地下水除砷应用中的研究进展

砷污染突发事件的频发严重威胁着地下水饮用水水源的水质安全，加之饮用水控制标准的提高，就对饮用水除砷技术提出了更高的要求，而纳滤(NF)膜分离技术为饮用水除砷提供了新的思路。首先概述了地下水中砷的存在形态、化学性质以及我国高砷地下水地区分布，然后分析了NF膜特点、除砷机理与性能，系统地阐述了各种因素包括膜操作因素（操作压力、膜回收率、膜排布方式等）和原水水质因素（pH、水温、共存离子、共存有机物及砷浓度与砷价态等），对NF膜除砷性能的影响。此外，对NF除砷的关键问题，如原水预处理、膜浓水处理、膜污染及其清洗等，也作了探讨。最后，总结了目前NF除砷应用中所面临的问题，探索性提出了NF膜技术在除砷应用中的研究方向。     

饮用水原水中微量阿特拉津去除方法试验研究

饮用水中微量有机物的污染是关系饮用水生态安全的重要问题。以饮用水中微量的内分泌干扰类除草剂阿特拉津为研究对象，分别采用微生物降解技术和光催化氧化技术对其进行降解，考察温度对阿特拉津降解效果的影响。研究结果表明：阿特拉津浓度为1 mg/L时，3种温度条件下，除锰功能菌MB4对阿特拉津均有明显的去除效果，降解时间为7 d时，阿特拉津的去除率达到65%。底物浓度为200 μg/L，3种温度条件下，活性炭负载二氧化钛（TiO₂/PAC）催化剂光降解阿特拉津30 min时，其去除率均达到90%。光催化氧化技术协同微生物降解技术在饮用水中微量的内分泌干扰物的去除中有广阔的应用前景。     

饮用水除砷材料吸附特性及影响因素分析

采用活性氧化铝、零价铁粉和载铁沸石作为吸附剂,通过静态吸附实验,研究3种饮用水除砷材料的吸附特性及影响因素。结果表明,在pH值为6.5,砷浓度为1 mg/L,投加量为2 g/L,25℃恒温的条件下,活性氧化铝、零价铁粉和载铁沸石分别在90 min、150 min和90 min达到吸附平衡状态,均较好符合langmuir等温吸附模型,对砷的最大吸附容量依次为7.3、3.3和3.9 mg/g。pH值和竞争性阴离子对砷的去除均有显著影响。降低溶液pH值能明显提高3种材料的除砷效率;水中磷酸根离子的存在,能够明显降低活性氧化铝和零价铁粉的除砷效率;水中硅酸根离子的存在,能够明显降低零价铁粉和载铁沸石的除砷效率。     

饮用水中卤代产物及前驱物的形成与控制

简述了目前国内对饮用水中卤代烃类化合物的研究现状，根据对饮用水中卤代产物的形成及浓度受水源水中前驱物、饮用水消毒处理方法等因素的影响，阐述了控制饮用水消毒过程中卤代烃的形成途径。     

磷酸盐的测定 水中磷酸盐的测定 钼-锑-抗比色法

简介水中磷酸盐的测定可分为可溶性磷酸盐及全磷两部分。测定全磷时可采用高氯酸—硝酸;硝酸—硫酸;或用过硫酸盐消解氧化,使水中各种状态的磷酸盐及有机磷化合物转化为正磷酸盐后测定。砷(V)的干拢可加除砷剂消除。     

饮用水中硝酸盐氮去除技术的研究与应用

简单介绍了几种去除饮用水中硝酸盐氮的技术方法及其在实际中的应用情况。对生物反硝化法和离子交换法去除饮用水中硝酸盐氮的情况做了比较详细的讨论。     

Removal of arsenic from drinking water by chemical precipitation--a modeling and simulation study of the physical-chemical processes.

A dynamic mathematical model was developed for removal of arsenic from drinking water by chemical coagulation-precipitation and was validated experimentally in a bench-scale set-up. While examining arsenic removal efficiency of the scheme under different operating conditions, coagulant dose, pH and degree of oxidation were found to have pronounced impact. Removal efficiency of 91-92% was achieved for synthetic feed water spiked with 1 mg/L arsenic and pre-oxidized by potassium permanganate at optimum pH and coagulant dose. Model predictions corroborated well with the experimental findings (the overall correlation coefficient being 0.9895) indicating the capability of the model in predicting performance of such a treatment plant under different operating conditions. Menu-driven, user-friendly Visual Basic software developed in the study will be very handy in quick performance analysis. The simulation is expected to be very useful in full-scale design and operation of the treatment plants for removal of arsenic from drinking water.     

Arsenic removal methods for drinking water in the developing countries: technological developments and research needs

Arsenic pollution of drinking water is a concern, particularly in the developing countries. Removal of arsenic from drinking water is strongly recommended. Despite the availability of efficient technologies for arsenic removal, the small and rural communities in the developing countries are not capable of employing most of these technologies due to their high cost and technical complexity. There is a need for the “low-cost” and “easy to use” technologies to protect the humans in the arsenic affected developing countries. In this study, arsenic removal technologies were summarized and the low-cost technologies were reviewed. The advantages and disadvantages of these technologies were identified and their scopes of applications and improvements were investigated. The costs were compared in context to the capacity of the low-income populations in the developing countries. Finally, future research directions were proposed to protect the low-income populations in the developing countries.     

Evaluating of arsenic(V) removal from water by weak-base anion exchange adsorbents

Arsenic contamination of groundwater has been called the largest mass poisoning calamity in human history and creates severe health problems. The effective adsorbents are imperative in response to the widespread removal of toxic arsenic exposure through drinking water. Evaluation of arsenic(V) removal from water by weak-base anion exchange adsorbents was studied in this paper, aiming at the determination of the effects of pH, competing anions, and feed flow rates to improvement on remediation. Two types of weak-base adsorbents were used to evaluate arsenic(V) removal efficiency both in batch and column approaches. Anion selectivity was determined by both adsorbents in batch method as equilibrium As(V) adsorption capacities. Column studies were performed in fixed-bed experiments using both adsorbent packed columns, and kinetic performance was dependent on the feed flow rate and competing anions. The weak-base adsorbents clarified that these are selective to arsenic(V) over competition of chloride, nitrate, and sulfate anions. The solution pH played an important role in arsenic(V) removal, and a higher pH can cause lower adsorption capacities. A low concentration level of arsenic(V) was also removed by these adsorbents even at a high flow rate of 250–350 h^?1. Adsorbed arsenic(V) was quantitatively eluted with 1 M HCl acid and regenerated into hydrochloride form simultaneously for the next adsorption operation after rinsing with water. The weak-base anion exchange adsorbents are to be an effective means to remove arsenic(V) from drinking water. The fast adsorption rate and the excellent adsorption capacity in the neutral pH range will render this removal technique attractive in practical use in chemical industry.     

Water reclamation during drinking water treatments using polyamide nanofiltration membranes on a pilot scale

The aim of this study was to investigate the performances of polyamide nanofiltration membranes during water reclamation. The study was conducted using nanofiltration concentrates obtained from two different nanofiltration drinking water treatment plants placed in the northern part of Serbia (Kikinda and Zrenjanin). Used nanofiltration concentrates contained high concentrations of arsenic (45 and 451 μg/L) and natural organic matter (43.1 and 224.40 mgKMnO₄/L). Performances of polyamide nanofiltration membranes during water reclamation were investigated under various fluxes and transmembrane pressures in order to obtain drinking water from nanofiltration concentrates and, therefore, reduce the amount of produced concentrates and minimize the waste that has to be discharged in the environment. Applied polyamide nanofiltration membranes showed better removal efficiency during water reclamation when the concentrate with higher content of arsenic and natural organic matter was used while the obtained permeates were in accordance with European regulations. This study showed that total concentrate yield can be reduced to ~5 % of the optimum flux value, in both experiments. The obtained result for concentrate yield under the optimum flux presents considerable amount of reclaimed drinking water and valuable reduced quantity of produced wastewater.     

Removal of pollutants from surface water and groundwater by nanofiltration: overview of possible applications in the drinking water industry

During the last decade, nanofiltration (NF) made a breakthrough in drinking water production for the removal of pollutants. The combination of new standards for drinking water quality and the steady improvement of the nanofiltration process have led to new insights, possible applications and new projects on lab-scale, pilot scale and industrial scale. This paper offers an overview of the applications in the drinking water industry that have already been realised or that are suggested on the basis of lab-scale research. Applications can be found in the treatment of surface water as well as groundwater. The possibility of using NF for the removal of hardness, natural organic material (NOM), micropollutants such as pesticides and VOCs, viruses and bacteria, salinity, nitrates, and arsenic will be discussed. Some of these applications have proven to be reliable and can be considered as known techniques; other applications are still studied on laboratory scale. Modelling is difficult due to effects of fouling and interaction between different components. The current insight in the separation mechanisms will be briefly discussed.     

A study of ground water contamination by arsenic in the residential area of Behala, Calcutta due to industrial pollution

Due to the discharge of industrial effluent after production of the insecticide Paris-Green [Copper acetoarsenite Cu(CH(3)COO)(2).3Cu(AsO(2))(2)] by a local factory at the P. N. Mitra Lane, Behala, ground water has become contaminated with arsenic. More than seven thousand people were using this arsenic contaminated tube-well water for drinking and house-hold purposes. Many people of the area were hospitalised and symptoms of arsenic toxicity were visible amongst a large number of the population. Analytical study reveals that soil around the area of effluent dumping point, which is at the middle of the locality, contains a very high concentration of arsenic and copper. For the last 20 years this factory had been producing 20 tons of Paris-Green per year and had been dumping its effluent in that area. It seems, the effluent treatment for arsenic removal was not adequate and finally arsenic percolated to the underground aquifers. Consequently, arsenic concentration in the ground water is very high. Both arsenite and arsenate are present in ground water. An alternate source of water other than the ground water is immediately necessary for the people of P. N. Mitra Lane.     

Possible treatments for arsenic removal in Latin American waters for human consumption

Considering the toxic effects of arsenic, the World Health Organization recommends a maximum concentration of 10 μg L⁻¹ of arsenic in drinking water. Latin American populations present severe health problems due to consumption of waters with high arsenic contents. The physicochemical properties of surface and groundwaters are different from those of other more studied regions of the planet, and the problem is still publicly unknown. Methods for arsenic removal suitable to be applied in Latin American waters are here summarized and commented. Conventional technologies (oxidation, coagulation-coprecipitation, adsorption, reverse osmosis, use of ion exchangers) are described, but emphasis is made in emergent decentralized economical methods as the use of inexpensive natural adsorbents, solar light technologies or biological treatments, as essential to palliate the situation in poor, isolated and dispersed populations of Latin American regions.     

Adsorption of arsenic(V) by iron-oxide-coated diatomite (IOCD)

Purposes and aims  

Economically efficient methods for removing arsenic from the drinking water supply are urgently needed in many parts of the world. Iron oxides are known to have a strong affinity for arsenic in water. However, they are commonly present in the forms of fine powder or floc, which limits their utility in water treatment. In this study, a novel granular adsorbent, iron-oxide-coated diatomite (IOCD), was developed and examined for its adsorption of arsenic from water.     

A global health problem caused by arsenic from natural sources

Arsenic is a carcinogen to both humans and animals. Arsenicals have been associated with cancers of the skin, lung, and bladder. Clinical manifestations of chronic arsenic poisoning include non-cancer end point of hyper- and hypo-pigmentation, keratosis, hypertension, cardiovascular diseases and diabetes. Epidemiological evidence indicates that arsenic concentration exceeding 50 microg l(-1) in the drinking water is not public health protective. The current WHO recommended guideline value for arsenic in drinking water is 10 microg l(-1), whereas many developing countries are still having a value of 50 microg l(-1). It has been estimated that tens of millions of people are at risk exposing to excessive levels of arsenic from both contaminated water and arsenic-bearing coal from natural sources. The global health implication and possible intervention strategies were also discussed in this review article.