环境科学与工程专业英语翻译

Reading Material : Analytical Technique and Methodology

第八单元：空气污染物的来源和类型

第八单元 Reading Material : Type and Sources of Air Pollutants [ II J

阅读材料：空气污染物的类型和来源（Ⅱ）

What are PCBs? 什么是多氯联苯？

There are 209 possible chlorinated biphenyls, ranging in physical characteristics. 大概有209种氯化联苯，其物理性质不同。The mono-and dichloro biphenyls ( 27323-18-8), ( 25512-42-9) are colorless crystalline compounds that when burned in air give rise to soot and hydrogen chloride. 一氯联苯和二氯联苯（27323-18-8），（25512-42-9）是无色晶体的化合物，当它们在空气中燃烧会产生烟尘和氯化氢。The most important products are tri-chlorobiphenyls,tetrachlorobiphenyls, pentachlorobiphenyls and/ or hexachlorobiphenyls. 最重要的产品是三-氯化联苯，四氯联苯，五氯联苯和/或六氯联苯。

Chlorinated biphenyls are soluble in many organic solvents and in water only in the ppm range. 多氯联苯可溶于有机溶剂和仅在水的百万分之一ppm（part per million）的范围内溶解。Although chemically stable (including to oxygen of the air) they can be hydrolyzed tooxybiphenyls under extreme conditions forming toxic polychlorodibenzofurans. 氯化联苯易溶于在许多有机溶剂和水只有在的范围内的可溶性。虽然化学稳定性（包括空气中的氧气）

但是在一定条件下，多氯联苯可水解氧化成二氧化苯极端条件下形成的有毒的多氯代苯并二恶英。

The PCB class of compounds received substantial attention and notoriety when in 1968, in Japan,accidental poisoning occurred by cooking rice in bran oil contaminated by PCBs. 在1968年，多氯联苯类化合物受到实质性的的关注和得到臭名，日本用受到多氯联苯污染的米糠油做饭的意外中毒事件。Over 1000 patients suffered from various morbid symptoms. 超过1000例患者出现各种病态症状。A similar poisoning occurred in Taiwan in 1979. Causative agents were considered to be coconaminants of PCBs such as poly-chlorinated dibenzofurans that are secondarily formed during heating of PCBs congeners in commercial PCB mixtures and require a second look at PCB toxicity. 1979年台湾有一个类似的中毒事件。病原体被认为是如多氯二苯并呋喃的多氯联苯，其次是PCBs多氯联苯同系物在商业PCB混合物在加热过程中形成的，需要第二次看看PCB的毒性。

PCB regulation多氯联苯的管理

Because of concerns regarding PCB' s health effects and evidence of presence and persistence in the environment further manufacture of the chemical was banned under The 1976 Toxic Substance Control Act. 由于担心多氯联苯对健康的影响和证明存在以及持续在环境中会进一步制造化学物质的，在1976年美国有毒物质控制法中被禁止了。PCB regulations provide deadlines for removal of most in-use capaci-tors and transformers containing PCBs · and limit time for storage for disposal to one year. 多氯联苯的

管理提出最后期限为了最大去除使用电容器和变压器逗留的多氯联苯和限制储存一年就要处理。EPA has allowed continued use of PCBs in electrical transformers and capacitors when the agency did not pose unreasonable risk. 当经销产品不会产生过度的危险时，环境保护局允许继续使用含多氯联苯的电子电容器和变压器。Capacitors, except those in isolated areas should have been removed by October 1988, and transformers of a certain size in or near commercial buildings should be removed by October 1990. 电容器，除了那些分散地方的应该被移走在1988年10月之后，变压器的某一些型号和靠近商业建筑的应该被移走在1990年10月后。

EPA regulations require that PCBs taken out of service be disposed of either by specially designed high temperature incinerators needed to break high concentrations of PCBs to harm-less components or by alternate destruction methods approved by the agency. Environmental Protection Agency 美国环保署，法规要求PCB服务多氯联苯或者处置的，通过特别设计的高温焚化炉需要打破高浓度的多氯联苯的无害组件或替代由该机构批准的销毁方法。Oils contami-nated with low concentrations (50-500ppm) may be disposed by high efficiency boilers. 低浓度（50?500PPM）污染的油可以通过高效率的锅炉处理。

The limited number of incinerators approved for PCB incineration and the high cost of building additional incinerators have given incentive for alternate destruction methods. Alternate technologies must be capable of operating as effectively as EPA' s incineration effi-ciency. 批准用于焚

烧多氯联苯的焚烧炉数量被限制和成本高且附有焚烧炉的建筑鼓励使用一一分解的方法。选择的技术的运转效率必须能够达到环境保护局的焚烧效率。

PCBs in electrical transformers 多氯联苯的电流体变压器

There were 304 million lb of PCBs used as electrical fluid in approximately 150000 askarel ( non-flammable electrical fluid) transformers in the United States. 在美国有304百万磅的多氯联苯被当做电流体使用，大约150000阿斯卡列（不易燃的电流体）变压器。About 70000 PCB trans-formers are in or near commercial buildings that are open to the public. 大约70000多氯联苯变压器建在或靠近对公众开放的商业建筑。About 40000 of these transformers are owned by electrical utilities.

Approximately 15000 of these transformers are used in the food and feed industry. 大约40000这些变压器缺少电设施。大约15000这些变压器被使用在食品和饲料工业。Utilities and other industries must maintain or dispose of approximately 150000 askarel-type transformers that may develop leaks. 公用事业等行业必须保持或处置约150000氯代联苯-型变压器可能出现的漏洞。 Each year, an estimated 317 askarel-type trans-formers can be expected to leak. Each will lose about 5. 3 gal or 66 lb of PCBs. 公共设施和其他工业必须维护或处理大约150000阿斯卡列型变压器可能产生的泄露，每一年，估计317阿斯卡列型变压器被暴露泄露，将损失5.3㎡/s或66磅多氯联苯。

Transformers classification变压器的分类

The EPA has three classification for transformers: 环保局已对变压器

三分类： PCB transformers contain 500 or more ppm PCBs. 多氯联苯变压器，多氯联苯含量在百万分之500或超过百万分之一。They must be inspected quarterly for leaks, and detailed records must be kept. 每季度被检查出的泄露会被详细的记录并保存。No maintenance work involving removal of the core is allowed .除去核心没有维持工作涉及的是被允许的。

At the end of the transformers' useful life, it must be destroyed in an EPA-approved facility, or the transformer liquid must be incinerated and the carcass landfilled. 在变压器有效寿命的尽头，它会被环境保护局支持的设施销毁，或变压器的液体被焚烧和外壳被掩埋。The courts and the EPA have held the original transformer owner liable for leakage that may occur for as long as the carcass remains in the landfill. 环境保护局要呼吁变最初压器拥有者对液体泄漏负责任并且提供足够大的场地对变压器掩埋。

PCB-contaminated transformers contain between 50 and 400 ppm PCBs and require an-nual inspection. The rule concerning disposal, maintenance, and record keeping are less re-strictive and less costly than those for PCB transformers. 受多氯联苯污染的变压器，多氯联苯含量在百万分之50至百万分之400之间和要求必须每年检查。管理涉及处理、维护、记录保持在最小限制或者接近多氯联苯变压器要求的含量。

Non-PCB transformers have less than 50 ppm PCBs and are exempt from the burden-some rules and requirements that apply to PCB and PCBs contaminated transformers. 没有多氯联苯的变压器，多氯联苯含量少于百万分之50和免除了一些繁杂的规则和要求比在应用于多氯联苯变压器和受多氯联苯

污染的变压器。Non-PCB transformers are granted favor under the Toxic Substances Control Act. 没有多氯联苯的变压器被包含在美国有毒物质控制法里。

Analysis of PCBs 多氯联苯分析

Analytical methods most frequently used for detecting chlorinated biphenyls are capillary col-umn gas chromatography coupled with mass spectrometry in the MID ( Multiple Ion Detec-tion) mode and capillary column gas chromatography with ECD ( Electron Capture Detec-tor). 分析法最频繁用于发现含氯联苯，在多离子检测的模式下顶空毛管气象色谱与质谱分析结合、顶空毛管气象色谱与电子捕获测器结合。HPLC ( High Pressure Liquid Chromatography) and infrared spectroscopy are applica-ble to a limited extent. 高效液相色谱和红外光谱适用于限制的范围。Summary PCB determinations are also possible, though not usual. These require exhaustive chlorination and measurement of the decachlorbipheny content or dechlorination and subsequent biphenyl measurement.总结，多氯联苯的测定尽管不常用，也是有可能的。这是需要彻底的氯化作用好十氯联苯内容的测定或者脱氯后联苯的测定。

Infrared tested on PCBs 多氯联苯的红外测试

Infrared thermal treatment technology was field tested for

effectiveness on PCBs contamina-ted soil at two Superfund sites during 1986.

在1986年期间，红外热治疗技术在俩个超级基金地被现场检测受多氯联苯污染的土地的有效性。The transportable pilot system consisted of a primary furnace through which solid/ semisolid wastes were conveyed on a wire mesh belt. 移动式试验系是由一个一次火炉通过固体/半固体废物被传送到钢丝网运输带。The heat source was supplied by electric glow bars in lieu of gaseous fuels. 火源通过发电光棒代替气体燃料提供。 Residence times and furnace

temperatures could be controlled manually or automatically giving uniform ash. 为了提供均化灰分，停留时间和燃烧炉温度可以手动或自动控制。A secondary chamber, heated by electric or gaseous fuels, followed the primary furnace and provided temperatures m excess of 220° F. The system was designed to comply with all RCRA and TSCA requirements.二次火炉通过电或气体燃料加热，与一次火炉一样和提供的温度超过2200F。系统被设计成符合资源保护和回收法案以及美国有毒物质控制法要求。

Select from \"Paul N. C. , High hazardous pollutants, Asestos, PCBs, dioxins, biomedical wastes, PollutionEngineering, Vol. 21, No. 2, 1989\"

unit 12 Text: Water Pollution and Pollutants

第十二单元：水污染与污染物

The relationship between polluted water and disease was firmly established with the cholera epidemic of 1854 in Londo, England. Protection of public health, the original purpose of pollution control, continues to be the primary objective in many areas. 1854年英国伦敦爆发了大规模的流行性霍乱。此事明确地证实了污水和疾病之间的关系。当初以公共健康为目的所

采取的污染控制，依然是许多地区的主要目的。 However, preserva-tion of water resources, protection of fishing areas, and maintenance of recreational waters are additional concerns today. 然而，水资源的保持，产鱼区的防护，以及娱乐活动用水的维持在今天也成为关注的焦点。Water pollution problems intensified following World War II when dramatic increases in urban density and industrialization occurred. 紧随第二次世界大战之后所产生的城市人口密度突增和工业化进程的加剧，都使得水污染问题越见明显。Concern over water pollution reached a peak in the mid-seventies.致使对于水污染的关注程度在70年代中期达到了顶峰。

Water pollution is an imprecise term that reveals nothing about either the type of pollu-ting material or its source. The way we deal with the waste problem depends upon whether the contaminants are oxygen demanding, algae promoting, infectious, toxic, or simply un-sightly. 水污染是一个不准确的术语，它并未指出污染物的种类和来源。而我们处理废水问题的方式往往取决于以下几个方面：污染物是否需要氧气，是否助长藻类，是否有传染性，是否有毒，或者仅仅是否好看。 Pollution of our water resources can occur directly from sewer outfalls or industrial discharges (point sources) or indirectly from air pollution or agricultural or urban runoff ( nonpoint sources). 水源的污染可能直接来自生活污水的排放或工厂污水排放（点源），也可能间接地由空气污染、农业排水或城市排水（非点源）所引发。

Chemically pure water 1s a collection of H2 0 molecules--nothing else. 化学上所谓的纯水仅仅是水分子的集合。Such a sub-stance is not found in

nature--not in wild streams or lakes, not in clouds or rain, not in falling snow, nor in the polar ice caps. 无论在野外的河流或湖泊、云层或雨水中，还是在下雪期间，极地的冰帽地区，这种物质在自然界均不能找到。Very pure water can be prepared in the laboratory but only with considerable difficulty. 然而在实验室中可以制备非常纯净的水，但是存在一定的困难。Water accepts and holds foreign matter.因为水极易接受和容纳外来物质。

Municipal wastewater, also called sewage, is a complex mixture contammg water( usually over 99 percent) together with organic and inorganic contaminants, both suspen-ded and dissolved. 城市污水，也被称作生活污水，是一种复杂的混合物，它包含水（通常超过99％）以及悬浮或溶解的有机和无机污染物。The concentration of these contaminants is normally very low and is ex-pressed in mg/L, that is, milligrams of contaminant per liter of the mixture. 这些污染物的浓度通常很低并且以mg/L来表示，也就说，每升混合物含有多少毫克污染物。This is a weight-to-volume ratio used to indicate concentrations of constituents in water, wastewater, industrial wastes, and other dilute solutions.重量与体积比也常用来表示在水、废水、工业废水和其它稀释溶液中的污染物浓度。

Microorganisms. Wherever there is suitable food, sufficient moisture, and an appropri-ate temperature, microorganisms will thrive. 微生物 任何地方只要存在适合的食物，充足的湿度和适当的温度，微生物即可大量繁殖。 Sewage provides an ideal environment for a vast array of microbes, primarily bacteria, plus some viruses and protozoa. 而生活污水为各种各样的微生物

提供了一个理想的环境。这些微生物主要是细菌，某些病毒和原生动物。Most of these microorganisms in wastewater are harmless and can be employed in biological processes to convert organic matter to stable end products. 废水中的大多数微生物是无害的，并且可借助生化过程，将有机物转化为稳定的最终产物。However, sewage may also contain pathogens from the excreta of people with infectious diseases that can be transmitted by contaminated water. 但是当一些人患有可通过有毒废水传播的传染性疾病时，其排泄物所携带的致病病原体，极有可能成为污水的组成部分。 Waterborne bacterial diseases such as cholera, typhoid, and tuberculosis, viral dis-eases such as infectious hepatitis, and the protozoan-caused dysentery, while seldom a prob-lem now in developed countries, are still a threat where properly treated water is not avai-lable for public use. 虽然在发达国家，类似于水传播的细菌性疾病，例如霍乱、伤寒和肺结核，病毒性疾病例如传染性的肝炎和原生虫引起的痢疾，已经不再是问题，但是在那些经过适当处理过的污水不能被公共利用的地区仍然存在着很大威胁。Tests for the few pathogens that might be present are difficult and time con-suming, and standard practice is to test for other more plentiful organisms that are always pres-ent ( in the billions) in the intestines of warm-blooded animals, including humans.对于少量存在的病原体的检测是相当困难和耗时的。其标准做法是检测存在于包括人类在内的（数十亿）热血动物肠胃中的有机物。

Solids. 固体The total solids ( organic plus inorganic) in wastewater are, by definition, the res-idues after the liquid portion has been

evaporated and the remainder dried to a constant weight at 103℃. 废水中的总固体（包括有机的和无机的）是指液体部分被蒸发，并且在103℃烘干至恒重的残余物。 Differentiation between dissolved solids and undissolved, that is, suspended, solids are accomplished by evaporating filtered and unfiltered wastewater samples. 区分可溶性固体和悬浮固体的方法，是通过蒸发过滤的和没有通过过滤的废水样品来进行的。The difference in weight between the two dried samples indicates the suspended solids content. 两种烘干样品质量的差值即表示悬浮物的质量。To furt her categorize the residues, they are held at 550\"C for 15 minutes. The ash remaining is considered to represent inorganic solids and the loss of volatile matter to be a measure of the organic content.将残留物在550℃温度下保持15分钟以进一步分类，剩余的灰代表了无机物，失去的挥发物则代表有机物的重量。

Suspended solids (SS ) and volatile suspended solids ( VSS ) are the most useful. 悬浮固体（SS）和挥发性的悬浮固体（VSS）是最有用的。SS and BOD (biochemical oxygen demand) are used as measures of wastewater strength and process performance. SS和BOD（生化需氧量）是废水的受污染程度及其过程性能的指标。VSS can be an indicator of the organic content of raw wastes and can al-so provide a mea:mre of the active microbial population in biological processes. VSS可以指示废水中有机物的含量，也可以衡量在生化过程里活性的微生物群。

Inorganic constituents. The common inorganic constituents of wastewater include:

无机成分 废水中常见的无机成分包括：

1. Chlorides and sulphates. Normally present in water and in wastes from humans.

1．氯化物和硫酸盐。常见于人类排放的废水和废物中。

2. Nitrogen and phosphorous2．氮和磷。以各种形式（有机的和无机的）存在于来自人类排放的废物，和含磷的清洁剂。

3. Carbonates and bicarbonates? . Normally present in water and wastes as calcium and magnesium salts.

3．碳酸盐和碳酸氢盐。通常以钙盐和镁盐的形式出现在水和废物中。 4. Toxic substances. Arsenic, cyanide, and heavy metals such as Cd, Cr, Cu, Hg, Pb, and Zn are toxic inorganics which may be found in industrial wastes.

4．有毒物质。砷，氰化物和在工业废水中可以找到的有毒无机物：Cd（镉）、Cr（铬）、Hg（汞）、Pb（铅）、Zn（锌）等重金属。

In addition to these chemical constituents, the concentration of dissolved gases, especially oxygen, and the hydrogen ion concentration expressed as pH are other parameters of inter-est in wastewater. 除了这些化学成分，溶解气体的浓度，尤其是氧气，用pH值所表示的H离子的浓度也是其它引起废水注意的指标。

Organic matter. 有机物 Proteins and carbohydrates? constitute 90 percent of the organic matter in domestic sewage. 生活污水中的有机物90％是由蛋白质和碳水化合物组成。The sources of these biodegradable contaminants include excreta and urine from humans; food wastes form sinks; soil and dirt from bathing; washing, and laun-dering; plus various soaps, detergents, and other cleaning products.这些可生物降解的物质包括人类的尿和排泄物、洗涤槽的食物残渣、土和洗澡的脏物、洗衣用水和洗烫水，及各种肥皂、洗洁精和其他清洁产品。

Various parameters are used as a measure of the organic strength of wastewater. 各种指标用来衡量废水中有机物浓度。One method is based on the amount of organic carbon ( total organic carbon, or TOC? ) present in the waste. 一种方法是基于废水中的有机碳的总量（即总有机碳TOC）。TOC is determined by measuring the amount of C02 produced when the organic carbon in the sample is oxidized by a strong oxidizer and comparing it with the amount in a standard of known TOC. 总有机碳是由样品中有机碳被强氧化剂氧化成二氧化碳的数量与已知的总有机碳的标准数量的比较所决定的。

Most of the other common methods are based on the amount of oxygen required to con-vert the oxidizable material to stable end products. 常见的另一种方法是根据把氧化物转化成稳定的最终产物所需要的氧气。Since the oxygen used is proportional to the oxidizable material present, it serves as a relative measure of wastewater strength. The two methods used most frequently to determine the oxygen requirements of wastewater are the COD?

and BOD? tests. 因为需氧量正比于污水中现存的氧化物，它可以用于废水浓度的相对衡量。通常确定废水需氧量的两种方法是COD（化学需氧量）和BOD（生化需氧量）的测定。The COD, or chemical oxygen demand, of the wastewater is the measured amount of oxygen needed to chemically oxidize the organics present; the BOD, or biochemical oxygen demand, is the measured amount of oxygen required by acclimated mi-croorganisms to biologically degrade the organic matter in the wastewater. 化学需氧量，是用化学方法氧化有机物的需氧量。而生化需氧量，是通过适应环境的微生物的以生物的方式降解废水中的有机物的需氧量。

BOD is the most important parameter in water pollution control. It is used as a measure of organic pollution, as a basis for estimating the oxygen needed for biological processes, and as an indicator of process performance. 在水污染控制理论中，生化需氧量是最重要的参数。生化需氧量用于测定有机物污染，是评估生物反应需氧量的基础和反应过程的指标。

The amount of organic matter in water or wastewater can be measured directly ( as TOC, for example), but this doesn' t tell us whether the organics are biodegradable or not. 我们可以直接地测定水或者废水中的有机物含量（例如测定总有机碳），但是这并不能告诉我们有机物是否有被生物降解。 To measure the amount of biodegradable organicsCD , we use an indirect method in which we measure the amount of oxygen used by a growing microbial population to convert ( oxi-dize) organic matter to C02 and H2 0 in a closed system. 为了测定可生物降解的有机物量，我们用一种间接的方法，也就是在一

个封闭的系统里，测定将有机物转化（氧化）成二氧化碳和水所用的生长的微生物群的耗氧量。The oxygen consumed, or bio-chemical oxygen demand (BOD), is proportional to the organic matter converted, 耗用的氧气，或生化需氧量，正比于有机物的转化量，and therefore BOD is a relative measure of the biologically degradable organic matter present in the system. 因此，生化需氧量是系统中生物降解有机物的相对衡量。Because biological oxidation continues indefinitely, the test for ultimate BOD has been arbitrarily limited to 20 days, when perhaps 95 percent or more of the oxygen require-ment has been met.因为生物氧化过程可以无限次地进行，最终生化需氧量的测定被限定为20天，这个时间能够满足95%或以上的微生物氧气需求。Even this period, however, is too long to make measurement of BOD useful, 但是过程时间过长，致使生化需氧量的测定没有效用， so a five-day test, BODs ?, carried out at 20°C, has become standard.所以一种五天式的测定，即将水样置于20℃的黑暗环境五天，作为生化需氧量的标准。The rate of the BOD reaction depends on the type of waste present and the temperature and is assumed to vary directly with the amount of organic matter (organic carbon) present.生化需氧量的反应速度取决于存在的废水类型、温度以及假设其随着存在的有机物（有机碳）的数量的变化趋势。

Unit 14

Text: Water Purification

Water molecules have no memory, and therefore his silly to talk about the number of times that the water you drink has been polluted and repurified,

as if the molecules gradually wore out. 水分子是没有记忆力的，所以谈论被污染和被净化的饮用水的次数是没意义的，例如分子的逐渐损耗。All that is important is how pure it is when you drink it.而当我们饮水的时候到底它有多纯净才是最重要的。

The purification of water has developed into an elaborate and sophisticated technology. 水的净化已经发展为一项复杂的和尖端的技术。However, the general approaches to purification should be comprehensible, and in some ca-ses even obvious, from a general understanding of the nature of water pollution. 然而，污水净化的本质的总方法是容易理解的，在某些情况下也是明显的。

Impurities in water were classified as suspended, colloidal, or dissolved. 里面的杂质分类为悬浮的，胶体的，或者是溶解的。Suspended particles are large enough to settle out or to be filtered. 水悬浮的颗粒物是大得足够沉降下来或者可以被过滤掉的。Colloidal and dissolved impurities are more difficult to remove. 胶体的颗粒物和溶解的颗粒物是更难除去。One possibility is somehow to make these small particles join to-gether to become larger ones, which can then be treated as suspended matter. 一是可以用某些方法使小的颗粒物结合起来变成大的颗粒物，然后把大的颗粒物作为悬浮物来进行处理。Another possi-bility is to convert them to a gas that escapes from the water into the atmosphere. Whatever the approach, it must be remembered that energy is required to lift water or to pump it through a filter采取哪一种方法，必须记住，提升水或用泵将水输送到通过过滤床都需要能量。

With these principles m mind, consider the procedures used in purifying municipal waste waters. 以上面原则作为依据，来考虑用来净化城市废水的程度。The first step is the collection system. 第一步是收集系统。Waterborne wastes from sources such as homes, hospitals, and schools contain food residues, human excrement, paper, soap, de-tergents, dirt, cloth, other miscellaneous debris, and, of course, microorganisms. This mixture is called sanitary or domestic sewage. 水中的废物有各种各样的来源，例如家庭的，医院的，学校的含有食品的残余物，人类的排泄物，纸，肥皂，清洁剂，脏物，布，其他各种各样的杂物，当然还有微生物。这种混合物就叫做生活污水。(The adjective \"sanitary\" is rather inappropri-ate because it hardly describes the condition of the sewage; it pr_esumably refers to that of the premises whose wastes have been carried away). （“生活污水”这个形容词是很不合适的，因为它没有描述污水的情况；它可能是指那些废物排放出来的地方）。These waters, which are sometimes joined by wastes from commercial buildings, by industrial wastes, and by the runoff from rain, flow through a network of sewer pipes. 这些污水有时跟商业建筑废水，工业废水和雨水混合在一起，一同流进废水的管路网络里面去。Some systems separate sewage from rainwater, oth-ers combine them. 某些系统将雨水和生活污水分开，另一些系统又将两者结合起来。The combined piping is cheaper and is adequate in dry weather, but dur-ing a storm the total volume is apt to exceed the capacity of the treatment plant, so some 1s allowed to overflow and pass directly

into the receiving stream or river.结合的网络式是比较便宜的，而且适合干燥的天气，但在暴雨时，总的体积很容易超过污水处理厂的容量，所以某些水就允许溢流出去和直接排放到河流里面去。

Primary Treatment?初级处理

When the sewage reaches the treatment plant, it first passes through a series of screens that remove large objects such as rats or grapefruits, and then through a grinding mechanism that reduces any remaining objects to a size small enough to be handled effectively during the remaining treatment period. 当生活污水到达污水处理厂时，它首先通过一系列的滤网以除去如老鼠，葡萄柚似的大物体，和在接下来的处理时期里，通过一架磨碾机以减少剩下的物体的尺寸使其足够小能有效地被处理。The next stage is a series of settling chambers designed to re-move first the heavy grit, such as sand that rainwater brings in from road surfaces, and then, more slowly, any other suspended solids-including organic nutrients that can settle out in an hour or so. 下一步是设置一系列的沉淀池以除去初始的粗沙，例如雨水从路面带进的沙子，然后，慢慢地任何其它的悬浮固体—包括在一个小时能沉淀下来的有机营养物。Up to this point the entire process, which is called primary treatment, has been relatively inexpensive but has not accomplished much.直到这个阶段，称为初级处理，相对地便宜但并未完成净化的程度。

Secondary Treatment?二级处理

The next series of steps is designed to reduce greatly the dissolved or finely suspended organ-ic matter by some form of accelerated biological

action. 接下来的一系列步骤，是设计通过加速生化作用的某种形式来较大程度地减少溶解的或微小的悬浮有机物。What is needed for such decomposi-tion is oxygen and organisms and an environment in which both have ready access to the nu-trients. 分解需要氧气和微生物以及一种两者都易接近营养物的环境。 One device for accomplishing this 'objective is the trickling filter? . 达到这个目标的一种装置是滴滤池。 In this device, long pipes rotate slowly over a bed of stones, distributing the polluted water in continuous sprays. As the water trickles over and around the stones, it offers its nutrients in the pres-ence of air to an abundance of rather unappetizing forms of life. 这种装置，长管在由岩石填充而成的滤床上缓慢的旋转，通过持续地喷洒来分布这些污水。

An alternative technique is the activated sludge process. 另一个技术是活性污泥过程。 Here the sewage, after primary treatment, is pumped into an aeration tank, where it is mixed for several hours with air and bacteria-laden sludge. 废水，经过初级处理后，泵到一个混合空气和含有细菌的污泥几个小时的曝气池。The biological action is similar to that which occurs in the trickling fil-ter. The sludge bacteria metabolize the organic nutrients; the protozoa, as secondary con-sumers, feed on the bacteria. 生化作用与发生在滴滤池的相似。污泥中的细菌代谢转化成有机氧物；原生虫，作为二级消费者，吃掉细菌。 The treated waters then flow to a sedimentation tank, where the bacteria-laden solids settle out and are returned to the aerator. 处理过的水流到一个含有细菌的固体沉降的沉淀池去，然后返回到曝气

池。Some of the sludge must be removed to maintain steady-state conditions. 某些污泥必须被排放以维持一个稳定的状态。The activated sludge process requires less land space than the trickling filters, and, since it exposes less area to the atmosphere, it does not stink so much. 相对滴滤池来说，活性污泥需要占地少的面积，因为它需要曝气较小的面积，没有发出臭味。

The effluent from the biological action is still laden with bacteria and is not fit for dis-charge into open waters, let alone for drinking. 生化处理所排放的废水仍然含有细菌，和不适合排放到清洁的水源，更不用说饮用。Since the microorganisms have done their work, they may now be killed. 因为微生物完成其工作，现在就可以杀死他们了。The final step is therefore a disinfection process, usually chlorination. 最后一步是消毒过程，一般是加氯。Chlorine gas, 氯气， injected into the effluent 15 to 30 minutes before its final dis-charge, can kill more than 99 percent of the harmful bacteria. 在最后排放前加入到排水15至30分钟，就可以杀灭99%以上的有害细菌。

Tertiary or \"Advanced\" Treatments?三级或高级处理

Although considerable purification is accomplished by the time wastewaters have passed through the primary and secondary stages, these treatments are still inadequate to deal with some complex aspects of water pollution. 尽管此时的废水已经通过初级和二级处理，得到了相当大程度的净化，但是这些处理仍然不合适应对某些水污染的复杂方面。First, many pollutants in sanitary sewage are not removed. Inorganic ions, such as nitrates and

phosphates, remain in the treated waters; these materials, as we have seen, serve as plant nutrients and are therefore agents of eu-trophica tion. 首先，生活污水里面有很多污染物是不能清除的。无机的离子，例如硝酸盐和磷酸盐，仍然在处理过的水中;这些物质，正如我们所看到的，可以作为植物的营养物和水体的营养成分。

The treatment methods available to cope with these troublesome wastes are necessarily specific to the type of pollutant to be removed, and they are generally expensive. A few of these techniques are described below. 用于应付这些麻烦废水的处理方式是必需专门除去这类污染物，而且它们一般很昂贵。如下描述几种这些技术。

1. Coagulation and Sedimentation 1． 混凝和沉淀

As mentioned earlier in the discussion of biological treatment, it is advantageous to change little particles into big ones that settle faster. 正如在生物处理的讨论中我们早前提及的，将小的颗粒物转变成的大的能够快速沉淀的颗粒物是很有好处的。So it is also with inorganic pollutants. 所以它跟无机污染物同样道理。 Various inorganic colloidal particles are waterloving (hydrophilic) and therefore rather adhesive; in their stickiness they sweep together many other colloidal particles that would otherwise fail to settle out in a reasonable time. 各种各样的无机胶体颗粒是喜欢水的（亲水的）并且具有相当的粘附性；由于它们的粘附性它们一起带走很多其他难以在合理时间内沉降下来的胶体颗粒物。This process is called

flocculation. Lime, alum, and some salts of iron are among these so-called flocculating agents. 这个过程被称为絮凝。石灰，矾和某些铁盐都是这些所谓的絮凝剂。

2. Adsorption 2． 吸附

Adsorption is the process by which molecules of a gas or liquid adhere to the surface of a sol-id. 吸附是气体分子或液体分子粘附到固体表面的过程。The process is selective-different kinds of molecules adhere differently to any given sol-id. To purify water, a solid that has a large surface area and binds preferentially to organic pollutants is needed. 这个过程是具有选择性的—不同种类的分子以不同的方式粘附在任何固体。对于净化水，那些有着大的表面积并且结合倾向于有机污染物的固体是必需的。The material of choice is activated carbon, which is particularly effec-tive in removing chemicals that produce offensive tastes and odors. These include the biologi-cally resistant chlorinated hydrocarbons. 选择的物质是活性碳，它能够特别有效地除去产生令人讨厌的味道和臭味的化学品。这些化学品包括那些难以生物降解的氯代烃。

3. Other Oxidizing Agents 3． 其他氧化剂

Potassium permanganate (KMn04) and ozone (03 ) have been used to oxidize waterborne wastes that resist oxidation by air in the presence of microorganisms. 高锰酸钾和臭氧用于氧化那些抵抗空气中微生物的氧化的水中

废物。Ozone has the impor-tant advantage that its only byproduct is oxygen.臭氧有一个很重要的优点就是它仅存的副产物是氧气。

4. Reverse Osmosis 4． 反渗透

Osmosis is the process by which water passes through a membrane that is impermeable to dissolved ions. 渗透是一个水通过一种不透过溶解离子的膜的过程。In the normal course of osmosis, the system tends toward an equilibrium in which the concentrations on both sides of the membrane are equal. 在正常的过程中，系统倾向于一个平衡状态，在这个平衡状态中膜的两边的浓度是相同的。This means that the water flows from the pure side to the concentrated \"polluted\" side. This is just what we don't want, because it increases the quantity of polluted water. 这意味着水从纯净的一边流到富集污染物的一边。这并不是我们所希望的，因为这个过程增加了被污染的水的数量。However, if excess pressure is ap-plied on the concentrated side, the process can be reversed, and the pure water is squeezed through the membrane and thus freed of its dissolved ionic or other soluble pollutants. 然而，假如高压是加到富集污染物的一边，这个过程可被逆转，纯净水就被挤压通过这个膜，并且这样就除去了溶解的离子或者其他溶解的污染物。

Selected from \"] onathan Turk, Amos Turk. Environmental Science, Third Edition, Saunders College Publishing , The Drylen Press , USA , 1984\"

Reading Material: Principles of Wastewater Treatment

Effluent Requirements流出物要求

The primary objective of wastewater treatment is to remove or modify those contaminantsdetrimental to human health or the water, land, and air environment. Land disposal, evap-oration from ponds, and deep-well injection are occasional options, but usually the only practical outlets for the disposal of treated (or untreated) wastewater are streams, rivers, lakes, and oceans. 废水处理的主要目的是去除或改变对人体健康或水，土地和空气环境有害的那些污染物。土地处置，蒸发形成池塘和深井注入是偶然的选择，但通常处理已处理（或未处理的）废水的唯一实际渠道是河流，河流，湖泊和海洋。To protect these water resources, the discharge of pollutants into them must be controlled. 为了保护这些水资源，必须控制污染物排放到其中。This is done in North America by setting effluent requirements for BOD, SS, and fecal coliforms. 这在北美地区通过设置BOD，SS和粪大肠杆菌的污水要求来完成。Secondary treatment is normally necessary to meet these require-ments.通常需要二次处理以满足这些要求。

In the United States, for example, BODs or SS values in the effluent must not exceed an average of 30 mg/L. 例如，在美国，流出物中的BOD 5或SS值不得超过平均值30 mg / L。 The maximum limit for fecal coliforms is 200/100 mL (geometric mean). 粪大肠菌群的最大限量为200/100ml（几何平均值）。A further stipulation is that not less than 85 percent removal of BOD and SS must be provided. 另一个规定是必须提供不低于85％的BOD和SS去除率。Canadian requirements are similar, but some provinces use 15 mg/L as the maxi-mum for effluent BODs and SS. 加拿大的要求是类似的，但一些省份使用

15 mg / L作为污水BOD 5和SS的最大值。This implies a greater than 90 percent removal efficiency in the treatment of \"normal\" municipal wastewater. with a BODs of 200 mg/L.这意味着在BOD 5为200mg / L的“正常”城市废水的处理中，大于90％的去除效率。

Where receiving waters have limited assimilation capacity, contain excessive nutrients, provide essential water use, or support valuable aquatic life, then more stringent effluent requirements are warranted. 如果接收水的同化能力有限，含有过量营养物质，提供必要的水利用或支持有价值的水生生物，则需要更严格的污水要求。Such situations entail detailed investigations to evaluate the need for additional wastewater treatment. 这种情况需要详细调查，以评估是否需要额外的废水处理。 Treatment Processes处理过程

The suspended, colloidal, and dissolved contaminants ( both organic and inorganic ) m wastewater may be removed physically, converted biologically, or changed chemically. 废水中的悬浮，胶体和溶解的污染物（有机和无机）可以物理去除，生物转化或化学改变。 Physical Processes. 物理过程。

Gravity settling is the most common physical process for removing suspended solids from wastewater. It is employed in利用重量沉降是最为普遍的去除污水中的悬浮物固体的方法，包括：

? Removing grit ( defined as sand particles of 0. 2 mm diameter or greater) ·除去砂粒（定义为直径为0.2mm或更大的砂粒）

? Clarifying raw sewage and concentrating the settled solids ( called raw or prima ry sludge)

·澄清原污水并浓缩沉降的固体（称为原始或初始污泥）

? Clarifying biological suspensions and concentrating the settled floe ( called biological, activated, or secondary sludge)

·澄清生物悬浮液并浓缩沉降的絮状物（称为生物，活性或二次污泥） ? Gravity thickening of primary or secondary sludges. ·初级或次级污泥的重力增稠。 Biological Processes. 生物过程。

Most of the organic constituents in wastewater can serve as food (substrate) to provide energy for microbial growth. 废水中的大多数有机成分可以作为食物（底物）为微生物生长提供能量。This is the principle used in biological waste treatment, where organic substrate is converted by microorganisms, mainly bacteria ( with the help of protozoa) , to carbon dioxide, water and more new cells. 这是生物废物处理中使用的原理，其中有机底物由微生物（主要是细菌（在原生动物的帮助下））转化为二氧化碳，水和更多的新细胞。The microorgan-isms may be aerobic (requiring free oxygen), anaerobic (not requiring free oxygen), or facultative (growing with or without oxygen). 微生物可以是需氧的（需要游离氧），厌氧的（不需要游离氧）或兼性的（伴随或不伴随氧的生长）。Processes in which microorganisms use bound oxygen (from N02 for denitrification, for example) are often called

anoxic rather than an-aerobic.微生物使用结合氧（例如，用于脱氮的NO 3 - ）的方法通常被称为缺氧而不是厌氧。

In a continuous biological process, the system normally operates at some point on the growth curve toward the end of the declining growth phase, or into the endogenous phase where cells utilize their own protoplasm to obtain energy. 在连续生物过程中，系统通常在生长曲线上朝向下降生长阶段结束的某一点操作，或者进入内源阶段，其中细胞利用其自身的原生质来获得能量。Utilization of the logarithmicgrowth phase in wastewater treatment has been impractical, because substrate removal is in-complete and no economical way has been found to separate the microbial population from the liquid. 在废水处理中使用对数生长期是不切实际的，因为底物去除是不完全的，并且没有发现将微生物群体与液体分离的经济方法。

Aerobic/ Anoxic Processes. In aerobic processes ( i. e. molecular oxygen is present) , het-erotrophic bacteria ( those obtaining carbon from organic compounds) oxidize about one-- third of the colloidal and dissolved organic matter to stable end products ( C02 + H2 0) and convert the remaining two-thirds into new microbial cells that can be removed from the wastewater by settling. 有氧/缺氧过程。在需氧过程（即存在分子氧）中，异养细菌（从有机化合物获得碳的那些）将约三分之一的胶体和溶解的有机物氧化成稳定的终产物（CO 2 + H 2 O），并将剩余的两种 - 三者转化为新的微生物细胞，其可以通过沉降从废水中除去。

Ever since the importance of wastewater treatment became recognized,

municipalities and industries have relied almost exclusively on aerobic rather than anaerobic biological processes for treating their liquid organic wastes. 自从认识到废水处理的重要性以来，城市和工业几乎完全依赖于需氧而不是厌氧生物工艺来处理其液体有机废物。Aerobic treatment has predominated be-cause of its simplicity, stability, efficient and rapid conversion of organic contaminants to microbial cells, and relatively odor-free operation. 好氧处理主要是因为其简单，稳定，有效和快速地将有机污染物转化为微生物细胞，以及相对无臭的操作。 Anaerobic Processes. 厌氧过程。

In anaerobic biological processes (i.e. no oxygen is present), two groups of heterotrophic bacteria, in a two-step liquefaction/ gasification process, convert over 90 percent of the organic matter present, initially to intermediates ( partially stabilized end products including organic acids and alcohols ) and then to methane and carbon dioxide gas: 在厌氧过程（即不存在氧气）中，两组异养细菌在两步液化/气化过程中将超过90％的存在的有机物质转化为中间体（部分终产物，包括有机酸和醇）然后再进入甲烷和二氧化碳气体：The process is universally used in heated anaerobic digesters, where primary and biological sludges are retained for approximately 30 days at 35\"C to reduce their volume ( by about 30 percent) and their putrescibility, and thus simplify their disposal, usually on agri-cultural land. 该方法普遍用于加热的厌氧消化器中，其中初级和生物污泥在35℃下保持约30天以减少其体积（约30％）和它们的腐蚀性，并因此简化

其处理，通常在农田上。

Two major advantages of anaerobic processes over aerobic ones are, that they provideuseful energy in the form of methane and that sludge production is only about 10 percent of that from aerobic processes for converting the same amount of organic matter. 厌氧工艺有氧工艺的两个主要优点是它们以甲烷的形式提供有用的能量，并且污泥产量仅仅是用于转化相同量的有机物质的需氧工艺的约10％。This is advan-tageous in the treatment of high-strength wastes, where the handling of large volumes of sludge would be a problem. 这有利于处理高强度废物，其中处理大量污泥将是一个问题。 Chemical Processes. 化学过程。

Many chemical processes, including oxidation, reduction, precipi-tation, and neutralization, are commonly used for industrial wastewater treatment. 许多化学过程，包括氧化，还原，沉淀和中和，通常用于工业废水处理。For mu-nicipal wastewater, precipitation and disinfection are the only processes having wide applica-tion.对于城市废水，沉淀和消毒是唯一具有广泛应用的方法。

Chemical treatment alone or with other processes is frequently necessary for industrial wastes that are not amenable to treatment by biological means. 对于不适于通过生物学方法处理的工业废物，单独或与其它方法的化学处理经常是必要的。The oxidation of toxic cyanide to manageable cyanide ( with S02) or of hexavalent chromium to the nontoxic trivalent form in the disposal of plating wastes are examples. Chemical processes are also useful in

municipal waste treatment, where phosphorus concentrations are reduced and removal of solids in-creased by precipitation of these contaminants with metallic salts. 在处理电镀废物时，将有毒氰化物氧化成可控的氰化物（用SO 2）或将六价铬氧化成无毒的三价形式是实例。化学方法也可用于城市废物处理，其中降低磷浓度并且通过用金属盐沉淀这些污染物来增加固体的去除。

Disinfection of the effluent from wastewater treatment plants, generally by chlorina-tion, is desirable where there is a potential health hazard. However, the uncertainty as to when a hazard exists has resulted in wide variation in practices.

在存在潜在的健康危害的情况下，通常通过氯化对来自废水处理厂的流出物进行消毒。然而，关于危险何时存在的不确定性导致了实践的广泛变化。

Chlorine is the least expensive and most often used chemical for wastewater disinfection, but unfortunately it produces some undesirable side effects. 氯是用于废水消毒的最便宜且最经常使用的化学品，但不幸的是，它产生一些不期望的副作用。Organic matter present will com-bine with the chlorine to form chlorinated organics, some of which are known or suspected carcinogens (capable or causing cancer). 存在的有机物将与氯结合形成氯化有机物，其中一些是已知的或疑似致癌物（能够或引起癌症）。 The fear is that these chlorinated organics are a po-tential hazard to water supplies. Another concern is the toxicity of chlorine residuals to aquatic life. 担心的是，这些氯化有机物是对供应的水的潜在危害。另一个问题是氯残余物对水生生物的毒性。Residuals as low as 0. 05 mg/L are toxic to various species of

freshwater fish. Where disinfection is necessary for the protection of public health, but toxicity from chlorine residuals is unacceptable, either the effluent must be dechlorinated or alternatives to chlorination must be considered. 低至0.05mg / L的残留物对各种淡水鱼都有毒性。如果需要消毒来保护公众健康，但氯残余物的毒性是不可接受的，则必须对流出物进行脱氯或者必须考虑氯化的替代物。Unfortunately, experience with alternatives such as chlo-rine dioxide, other halogens, ozone, or ultraviolet light is extremely limited. 不幸的是，对二氧化氯，其他卤素，臭氧或紫外线等替代品的经验极为有限。Costs for chlo-rination and dechlorination or alternative disinfectrion methods are two to three times the cost of chlorination alone. Also, substitutes for chlorine have other disadvantages and un-known long-term effects. 氯化和脱氯或替代消毒方法的成本是氯化单独成本的两到三倍。There is no ideal disinfectant.此外，氯的替代品通常具有缺点和未知的长期效果。没有理想的消毒剂。

Not all of the available physical, biological, and chemical processes have been de-scribed, nor are all of the processes mentioned required in every wastewater facility. 并非所有可用的物理，生物和化学过程都已被描述，也不是所有在每个废水设施中提及的所有过程。The basic units in a typical municipal plant might consist of primary settling tanks, preceded by screening and grit removal; secondary treatment units for oxidation and settling; anaerobic sludge digesters; and chlorination facilities.在典型的市政工厂中的基本单元可以包括初级沉淀罐，在筛除和除砂之前;用于氧化和

沉降的二级处理单元;厌氧污泥消化池;和氯化设施。

Selected from \"]. Glynn Henry, Gray W. Heinke. Environmental Science and Engineering, Prentice-Hall International Editions, Pretice. Hall Englewood Cliffs, NJ, USA, 1989\"

Unit 17 text: Ion Exchange

Unit 17 离子交换

Ion exchange is a treatment technology applicable to离子交换是一种适用于以下污染物的处理技术：( a) metals in wastewater where the metals are present as soluble ionic species (e.g. , CrH and CrO??-);（a）以可溶解的离子形式存在于污水中的金属（例如，Cr3+和CrO42-）; (b) nonmetallic ani-ons such as halides, sulfates, nitrates, and cyanides; (b)非金属阴离子例如卤化物、硫酸盐、硝酸盐和氰化物；and ( c) water-soluble, ionic organic compounds including和（c）水可溶解的，离子性的化合物包括(1) acids such as carboxylics, sulfonics, and some phenols, at a pH sufficiently alkaline to yield ionic species, （1）酸类例如羧酸、磺酸和某些苯酚，以一个酸碱度足够高的碱性来产生离子的种类，(2) amines, when the solution acidity is suffi-ciently acid to form the corresponding acid salt, （2）胺，当溶液的酸性足够高来形成相对应的酸盐，and ( 3) quaternary amines and alkysul-fates. 和（3）四价胺和烷基硫酸盐。

Ion exchange, when used in hazardous waste treatment, is a reversible process in which hazardous cations and/ or anions are removed from an aqueous solution and are replaced by nonhazardous cations and/ or anions

such as sodium, hydrogen, chloride, or hydroxyl ions. 当用于危险性污水处理时，离子交换是一个可逆的过程，其中危险性的阳离子和/或阴离子从一个水溶液里被除去并且被非危险性的阳离子和/或阴离子代替，例如钠、氢、氯化物或者氢氧根。Ion exchange resins are cationic if they exchange positive ions ( cations) and anionic if they exchange negative ions (anions). 假如交换正离子（阳离子），离子交换树脂呈阳离子性，假如交换的是负离子（阴离子）则它们呈阴离子性。When the waste stream to be treated is brought into con-tact with a bed of resin beads ( usually in a packed column), an exchange of hazardous ions for nonhazardous ions occurs on the surface of the resin beads. 当将要处理的废水流接触到一床的树脂球（通常在填充柱里），危险性离子交换到非危险性离子在树脂球表面发生。 Initially, a nonhazrdous ion is loosely bound to the surface of the resin. 一开始，非危险性离子很松散地结合到树脂表面。When a hazardous ion is near the resin, it is prefer-entially adsorbed to the surface of the resin (based on the differences in ions potential), re-leasing the nonhazardous ion. 当危险性离子靠近树脂时，它倾向于吸附在树脂的表面（根据离子的差异），放出非危险性离子。

Cation exchange resins contain mobile positive ions, such as hydrogen (H+) or sodium (Na+ ), which are attached to immobile functional acid groups, such as sulfonic ( S03) and carboxylic ( coo- ) groups CD. 阳离子交换树脂所包含的可流动阳离子，如H+或Na+，它们结合在固定的酸性功能基团上，如磺酸基（SO3-）和羧基官能团（COO-）。 Anion exchange resins have immobile

basic ions, such as amine ( NH2 - ) , to which the mobile anions, such as hydroxyl ( OH- ) or chloride ce1-)' are attached. 阴离子交换树脂有固定的碱性离子，如胺（NH2-）,一些活动的离子例如氢氧根离子（OH）或者氯离子（Cl）结合到胺离子上去。

Ion exchange material 1s contacted with the solution containing the ion to be removed until the active sites in the exchange material are partially or completely used up ( \"exhaus-ted\") by that ion. 离子交换物接触到溶液，这种溶液含有将要被去除直到在交换物中的活性位被部分或全部使用掉（失活）为止的离子。

After exhaustion, the resin is then contacted with a relatively low volume of a very con-centrated solution of the exchange ion to convert (\"regenerate\") it back to its original form.失活之后，树脂再接触到一种相对来说低体积、浓度很高的交换离子的溶液来变回它原来的状态（再生）。

For instance, in the case of a sodium-based resin, a strong solution of sodium chloride is typically the regenerant solution. 例如，在以钠为基础的树脂的情况下，强溶解质氯化钠是典型的再生溶液。The regenerant solution forces the previously removed ions back into solution. This relatively low volume solution, now highly concentrated with the contaminant ions, must then be treated prior to disposal for recovery or removal of the hazardous cation or anion contaminants. 再生溶液迫使原先去除的离子返回到溶液中去。这种树脂，体积相对较小，而且高度富集了污染物离子，必须对回收或除去的危险性阳离子或阴离子污染物优先处理。There will

continue to be a high concentration of the regenerant ion (sodium in the above example) in the used regenerant solution because ex-cess regenerant ion is necessary to force the contaminant ions back into solution. 因为过量的再生离子必然促使污染物离子返回到溶液中去，所以，如上面例子中的钠，使用的再生溶液中的再生离子的浓度将会持续升高。The direc-tion and extent of the completion of the exchange reaction depend upon the equilibrium that is established between the ions in the solution ( M+ x-) and those in the exchange material (R-N+ ). 完成交换反应的方向和程度，取决于建立在溶液和交换物质中的离子的平衡关系。

Ion exchange process离子交换过程

Most ion exchange operations are conducted in packed columns. 大多数的离子交换反应发生在填料柱。The aqueous solution to be treated is continuously fed to either the top or the bottom of the column. 即将处理的水溶液持续地在填料柱的顶部或底部充当养料。A typical fixed-bed io n exchange column consists of a vertical cylindrical pressure vessel with corrosion-resistant linings. 一种典型的固定床离子交换填料柱，由一个防腐蚀的垂直圆柱形的压力容器内层组成。If appropriate, a filter is installed at the inlet of the column to remove suspended particles because they may plug the exchange resin. 因为悬浮物会堵塞交换树脂，所以如果合适的话，在填料柱的入口处安装一个过滤器来除去悬浮物。 Spargers are provided at the top and bot-tom of the column to distribute waste flow. 喷水器安装在填料柱的顶部或底部来分散废水流。Frequently, a separate distributor is used for the regenerant solution to ensure an even flow. 通常情况下，对于再

生液，有一种单独的分布器来保证均匀的水流。The resin bed, usually consisting of several feet of ion exchange resin beads, is supported by a screen near the bottom distributor or by a support bed of inert granular material. 通常由几英尺厚的离子交换树脂小球组成的树脂层，由在底部分布器附近的格栅或惰性颗粒物形成的支撑床所支撑。Externally, the unit has a valve manifold to permit downflow operation, upflow backwashing ( to remove any suspended material), injection of the regenerant solution, and rinsing of any excess regenerant. 在外部，该单元有一个阀门式的系统，允许向下流动的操作、反冲洗（用来去除悬浮物）、再生液的喷射，以及过量再生液的冲洗。

A typical process for a basic two-step cation/ anion ion exchange system includes a series treatment with separate cation and anion exchange systems. 对于一个基本的两步阳/阴离子交换系统来说，一个典型的步骤包括单独的阳离子和阴离子交换系统的串联处理。Some systems contain both anion and cation exchange resins in the same vessel. 在同样的容器，一些系统包括阴阳离子交换树脂。The pressure vessels used for ion exchange generally range in size from 2 to 6 feet in diameter for prepackaged modular systems, which typically handle 25 to 300 gpm flow rates, to a maximum custom size of 12 feet in diameter, which can handle flow rates up to 1150 gpm. 对于预先包装的标准系统，用于离子交换的压力容器直径一般在2~6英尺之间，处理流量为每分钟25到300加仑流量，而对于订做的最大直径为12英尺的压力容器，其最高处理流量可以达到每分钟1150加仑。The height of these vessels varies between 6 and 10 feet to provide adequate resin sto rage, distribution

nozzle layout, and freeboard capacity for bed expansion during backwashing. 这些容器的高度范围在6至10英尺之间，以提供适当的树脂储存、喷嘴的布局分布，以及提防在反冲洗期间固定床的膨胀所允许的自由空间容量。The nominal surface loading area of the ion exchange vessels ranges from 8 to 10 gpm/ft2离子交换容器的名义上的表面负载面积在每分钟8到10加仑每平方英尺之间。

Ion exchange is used to remove a broad range of ionic species from water including:

离子交换被应用于去除以下废水中的各种各样离子污然物：

1. All metallic elements when present as soluble species, either anionic or cationic.

1. 在溶液中呈现可溶性的所有金属元素，阴离子或阳离子

2. Inorganic anions such as halides, sulfates, nitrates, cyanides, etc.

2. 无机阴离子，例如卤化物，硫酸盐，硝酸盐，氰化物等等

3. Organic acids such as carboxylics, sulfonics, and some phenols, at a pH sufficiently alkaline to give the ions.

3. 当pH到达一定碱性程度时，从有机酸，例如羧酸，磺酸，和一些苯酚中电离出来的离子

4. Organic amines when the solution acidity is sufficiently acid to form the correspond-ing acid salt.

4. 当溶液到达一定酸性时，有机胺将生成的相对应的酸盐

Sorptive resins can remove a wide range of polar and non-polar organics.

吸附树脂可以除去各种各样极性和非极性的有机物。

A practical upper concentration limit for ion exchange is about 2500 to 4000mg/L. 离子交换的实际浓度上限大约是2500到4000mg/L。 A higher concentration results in rapid exhaustion of the resin and inordinately high regenera-tion costs. 因为过高的浓度会导致树脂的快速失活和过高的再生液费用。Suspended solids in the feed stream should be less than 50mg/L to prevent plug-ging the resins, and waste streams must be free of oxidants. 原料流中的悬浮固体必须少于50mg/L以防止堵塞树脂，而废水流中必须没有氧化剂。

This technology is used to treat metal wastes including cations (e.g., Ni, Cd, Hg) and anions (e.g., Cr04, Se04, HAs04). 这个技术被应用于处理含有金属的废水，包括阳离子（例如：Ni, Cd, Hg）和阴离子（例如：CrO4, SeO4, HAsO4）。Limitations are selectivity/competition, pH and suspe_nded solids. 它的局限性是选择性/竞争，酸碱度和悬浮固体。Highly concentrated waste streams ( greater than about 25000mg/L con-taminants) can usually be separated more cost effectively by other means. 高浓度的废水源（污然物浓度高于25，000mg/L）通常可以用其他方法更加有经济性地进行分离。High solid concen-trations (greater than about 50mg/L) should be avoided to prevent resin binding. 高固体浓度（高于50mg/L左右）必须避免，以防止树脂的堵塞。

Ion exchange is used to extract specific metals from solution. 离子交换被用于提取溶液中特定的金属。To date, some 30 synthet-ic \"metal loving\" compositions of resins that attract specific metals have been developed.

到目前为止，树脂中提取特定金属的大约30种合成的“亲金属的”成分已经得到了发展。The method of attraction employed by the synthetic compositions is similar to that of livi ng cells. 那些合成成分提取特定金属的方法与活细胞提取特定金属的方法类似。Natural cells have a built-in survival mechanism that is highly selective for the capture and transport of certain metals necessary for cellular nutrition, specifically iron, cobalt, zmc, copper, sodium, nickel, potassium, magnesium, and manganese. 自然的细胞有一个内在的生存机理，就是对于夺取和运输细胞营养所需的特定金属，尤其是Fe, Co, Zn, Cu, Na, Ni, K, My和Mn具有高度选择性。 The synthetic compounds are patterned after the high efficiency and natural metal extraction capability of living cells.那些合成物就是模仿活细胞的高效率和天然金属的提取能力制造出来的。

Specific ion exchange and sorptive resins systems must be designed on a case-by-case ba-sis. 特定的金属交换和吸附树脂方法必须根据具体的情况来设计。 It is useful to note that although there are three major operating models ( fixed bed cocurrent, fixed bed countercurrent, and continuous countercurrent), fixed bed counter-current systems are most widely used. 尽管那有三个主要的操作模型（固定床的顺流，固定床的逆流，和连续的逆流），但固定床的逆流方法是被最广泛地使用这个情况也是值得去注意的。 The continuous countercurrent system is suitable for high flows. 连续的逆流方法适合那些高流程。Complete removal of cations and anions ( \"demineralization\") can be accom-plished by using the hydrogen form of

a cation exchange resin and the hydroxide form of an anion exchange resin. 通过使用阳离子交换树脂的H物形态和阴离子交换树脂的OH物形态可以实现阳离子和阴离子的完全除去（“去除矿物质”）。 For removal of organics as well as inorganics, a combination adsorp-tive/demineralization system, can be. used. 除去有机物还有无机物，可以使用结合吸附/去除矿物质方法。In this system, lead beds would carry sorptive resins which would act as organic scavengers, and the end beds would contain anion and cat-ion exchange resins. 在这个方法中，前面床带吸附树脂那将作为有机物清除剂，而后面床包含阴离子和阳离子交换树脂。By carrying different types of absorptive resins ( e. g. , polar and non:- polar) , a broad spectrum of organics could be removed. 使用不同种类的吸附树脂（例如：极性的和非极性的），可以除去各种各样的有机物。

Capacities of resins vary greatly with the manufacturer of the resin. 树脂的性能因生产厂家的不同而有很大的变化。The amount of resin needed must be determined by chemical tests using the wastewater to be treated.所需树脂的数量必须取决于用于处理废水时的化学测试。A resin manufacturer should also be contacted to ensure the correct choice of resins. In order to facili-tate the proper selection, the following items of information should be available: 一个树脂生产厂家也应该保证树脂的正确选择。为了保证有适当的选择，以下的数据项目可用到：(1) name of hazardous material to be removed, （1）需被消除的有害物质的名称，(2) concentration (approximate) of hazardous sub-stance, （2）有害的悬浮物的浓度， (3) amount of wastewater

to be treated, （3）需处理的废水量， and (4) chemical analysis of ions.（4）离子的化学分析。

In a new development, Rohm and Haas have developed a family of six carbonaceous ad-sorbents produced by the pyrolysis of fully activated IERs. 在新的发展里，Rohm和Haas通过全面的高温分解活化的IERS，生产出一组6个碳的吸附机。After pyrolysis, the beads acquire a carbon shell that combines the high adsorbent activity of activated carbon with the physical strength and controlled pore size of the polymeric bead?.高温热解后，树脂颗粒的外壳炭化具有活性炭的高吸附活性，并具有物理强度和可控的聚合物颗粒孔径。 A major application for this carbo-naceous resin is groundwater remediation, where both high reactivity and selectivity are re-quired to capture selected contaminants to the ppm and ppb concentration range. 这个碳的树脂的一个主要应用是地下水的处理，地下水的处理有高的反应性和选择性，它要求捕获浓度范围为1/10000和1×10-9的污染物。

Applicability 应用性

The list pollutants for which the ion exchange system has proved effective includes alumi-num, arsenic, cadmium, chromium ( hexavalent and trivalent) , copper, cyanide, gold, iron, lead, manganese, nickel, palladium, platinum, selenium, silver, tin, zinc, and more. 离子交换系统对污染物的清单已证明是有效的，清单里包括铝，砷，钙，铬（六价的和三价的），铜，氰化物，金，铁，铅，锰，镍，钯，铂，硒，银，锡，锌，和其他。Thus,

it can be applied to a wide variety of industrial concerns. Because of the heavy concentrations of metals in their wastewater, the metal finishing industries utilize ion ex-change in several ways. 因此，它能够处理各种各样的工业污染问题。因为金属加工产业的废水中含有高浓度的金属，所以他们在许多方面都利用离子交换。As an end-of-pipe treatment, ion exchange is certainly feasible, but its greatest value is in recovery applications. 在末端的处理中，离子交换当然是可行的，但它在回收方面的应用却要最大的价值。It is commonly used as an integrated treatment to recover rinse water and process chemicals. Some electroplating facilities use ion exchange to concentrate and purify plating baths. 它经常用于回收清洗的水和加工化学品的中和处理。一些电镀工厂利用离子交换来浓缩和净化电镀液。Also, many industrial concerns, including a number of nonferrous metals manufacturing plants, use ion exchange to reduce salt concentrations in incoming water sources. 还有，一些工业企业，包括许多有色金属处理厂，其利用离子交换来减少进来水源的盐的浓度。

The ion exchange process may be used to remove cyanide in a ferrocyanide complex from wastewater. 离子交换过程可能是用于除去污水中的亚铁氰化络合物过程用氢化物沉淀法将化合物聚集起来。The process generates a concentrated stream of the complex, which may be treated using cyanide precipitation. 当氰化物与铁络合时，离子交换用于氰化物的去除。Ion exchange is applicable to cyanide removal when the cyanide is complexed with iron. Experimental data have shown that a specific resin is very

se-lective to the removal of iron cyanide complexes. 实验性数据表示，特定的树脂对铁氰络合物的去除是有很高的选择性的。

Ion exchange has been used in hydrometallurgical processing for recovery of valuable metals. 离子交换已经用于有用金属回收的冶金过程。Uranium processing and extraction is an active field for both liquid and solid ion ex-change. 铀的处理和提取是液体和固体离子交换中的一个活跃的领域。 It has also been used for removal and isolation of radioactive waste. 它已经用于放射性废物的去除和分离。 Ion exchange can also be used to remove certain organic compounds, however, in general there are other more competitive process available for this use. 离子交换也可用于去除某些有机化合物，然而，一般更加适用于其它竞争的过程。

With the exception of occasional for clogging or fouling of the resins, ion exchange has proved to be a highly dependable technology. 树脂除偶尔堵塞或结垢之外，离子交换被证明是高度可靠的技术。 Only the normal maintenance of pumps, valves, piping and other hardware used in the regeneration process is required. 只有泵、阀门、管道系统和其他硬件的正常维持是再生过程需要的。 Few, of any, solids accumulate within the ion exchangers, and those which do appear are removed by the regeneration process. 如果有的话，再生过程去除后的固体在离子交换器内累积是很少的。Proper prior treatment and planning can eliminate solid build-up prob-lems altogether. The brine resulting from regeneration of the ion exchange resin must usually be treated to remove metals before discharge. 适当的预处理

和措施可以避免固体积累问题。通常离子交换树脂的再生盐水在排放之前必须先除去金属。This can generate solid waste.这可能产生固体废物。

Selected from \"Robert Noye, Unit Operations in Environmental Engineering, Noye Publication , USA, 1994\"