环境工程专业英语unit7.ppt

Unit 7 Selection of Water Treatment Processes,05.12.2,Profession-related English,Watershed management should be considered part of the operation of a water-supply system, which（指代前面所说的事情） is very important to protect raw water quality. 流域管理应当被看作是供水系统运行的一部分，这对于保护原水质量十分重要。 Behind an intake structure, there comes water treatment process（倒装结构）. 在取水工程后面，是水处理过程。,Profession-related English,Profession-related English,Current pretreatment processes in municipal water treatment are screening, presedimentation or desilting, chemical addition, and aeration. 目前市政水处理中的预处理工艺有筛分，预沉淀或沉砂，化学混凝和曝气。 Presedimentation is regularly used to remove suspended matter from river water. 预沉淀习惯上用于从河水中去除悬浮物。,Chemical treatment, in advance of（在前面） in-plant coagulation, is most frequently applied to improve presedimentation, to pretreat hard-to remove substances, such as taste and odor compounds and color, and to reduce high bacterial concentrations. 在混凝处理前面，化学处理最频繁地被用作改善预沉淀，或对难去除的物质进行预处理，例如嗅味物质、色度和减小高的细菌浓度。,Profession-related English,Conventional chemicals used with presedimentration are the polyelectrolytes and alum. 用来进行预沉淀处理的传统的化学物质是高分子聚合物和铝。,Profession-related English,Aeration is customarily the first step in treatment for the removal of iron and manganese from well waters and a standard way to separate dissolved gases such as hydrogen sulfide and carbon dioxide. 对于从井水中去除铁和锰，习惯上曝气作为处理的第一步。同时，曝气也是分离诸如硫化氢和二氧化碳等溶解性气体的标准方法。,Profession-related English,Treatment processes used in water plants depend on the raw-water source and quality of finished water desired. 水厂使用的处理工艺依赖于原水水源和对处理水的期望。 The specific chemicals selected for treatment are based on their effectiveness to perform the desired reaction and cost. 处理中所选用的药剂是以它们的处理效果和费用为基础的。,Profession-related English,For example, activated carbon, chlorine, chlorine dioxide, and potassium permanganate are all used for taste and odor control. 例如，活性碳、氯、二氧化氯和高锰酸钾，都被用来控制嗅味。,Profession-related English,Excess chlorination, although least expensive, can create undesired trihalomethanes; activated carbon is the most effective chemical. 过量使用氯，尽管费用上增加很少，但产生不期望的三氯代甲烷；活性炭是最有效的化学剂。,Profession-related English,In surface-water treatment plants equipment for feeding two or three taste- and odor-removal chemicals is usually provided, so the operator can select the most effective and economic chemical applications. 在地表水处理厂，加药装置常常能用来投加两种或三种的去嗅味的化学剂，因此，操作工能够选择使用最有效经济的化学药品。,Profession-related English,There is no fixed rule for color removal applicable to all waters. 没有适用于所有水的固定的色度去除法则。 Alum coagulation with adequate pretreatment, and applying oxidizing chemicals or activated carbon, may provide satisfactory removal. 经过足够的预处理后使用铝絮凝剂、应用有氧化作用的化学品或活性炭，可以提供满意的去除。,Profession-related English,On the other hand, a more expensive coagulant might（be？） prove to be more effective and reduce overall chemical costs. 另一方面，价格较贵的絮凝剂也许被证明效果较好，从而降低了总的药剂费用。 Perhaps the most important consideration in designing water treatment processes is to provide flexibility. 也许，在进行水处理工艺设计的时候，最注重考虑的是它的适应性。,Profession-related English,The operator should have the means to change the point of application of certain chemicals. 操作工应当有办法调节投加特定药剂的点。 For example, chlorine feedlines are normally provided for pre-, intermediate-, and postchlorination. 例如，加氯的投药管线通常设置成可满足预氯化、中氯化和后氯化的要求。,Profession-related English,Multiple chemical feeders and storage tanks should be supplied so that various chemicals can be employed in the treatment process. 应当设置多个化学品进料器和储存池，这样在处理工艺中可以使用多种化学品。,Profession-related English,Degradation of the raw-water quality, or changes in costs of chemicals, may dictate a change in the type of coagulant or auxiliary chemicals used in coagulation. 原水质量下降，或化学品价格变化，可以改变絮凝剂的类型，或在絮凝处理时使用混凝剂。,Profession-related English,In the case of （在情况）surface-water treatment plants it is desirable to provide space for the construction of additional pretreatment facilities. 在地表水厂，预留空间用来建造附加的预处理设施，这是所期望的。,Profession-related English,The flow in river may change due to construction of dams, channel improvements, or upstream water use. 由于修建水坝，修缮渠道，或上游使用水，河流中的水流也许会改变。 The quality of water changes due to human alteration and occupation of the watershed. 由于人类在流域内的改造活动，水质发生改变。,Profession-related English,Concentrations of pollutants（主语） from disposal of municipal and industrial wastes and agricultural land-runoff may increase（谓语）. 来自于市政、工业废物和农田径流中的污染物质浓度也许增加。 Lakes can become more eutrophic. 湖泊变得更富营养化。,Profession-related English,The treatment plant described in Fig.2-2 is a groundwater plant with provisions for iron and manganese removal and lime softening. 图2-2中所表示的处理厂是一个地下水厂，包含铁、锰去除工艺和石灰软化处理。,Profession-related English,Profession-related English,氯化：抑制铁细菌的生长和铁、锰的初级氧化。,曝气：增加DO，氧化铁、锰，去除二氧化碳。,氯化：氧化还原残留的锰。,停留：允许氧化的完成。,去除铁、锰的去除。,氨：将残留的分子态氯转变成结合态的氯。,氟硅酸：氟化反应。,After installation, the plant capacity（设备生产能力） has been expanded and the treatment process converted to only iron and manganese removal by increasing the aerator capacity, adding chlorine feed after the aeration, and using the settling basin as a detention tank. 设备安装完成以后，水厂产量扩大，进而修正处理工艺，采取增加曝气量、在曝气之后投加氯，以及使用沉淀设备充当接触停留池等措施，只进行铁和锰的去除 。,Profession-related English,At present (现在,目前) this plant is only capable of（有能力) performing oxidation by aeration and chlorination for iron and manganese removal and disinfection. 目前，这个厂子只是借助曝气和氯化的氧化作用去除铁和锰，并进行消毒。,Profession-related English,Finished water quality is excellent all year round because of the stable character of the well supply. 由于井水水质稳定,处理水的水质全年优质。 The treatment plant in Fig.2-3 is a typical conventional plant for surface water treatment built in 1950 s. 图2-3所示的处理厂建于19世纪50年代，是一座典型的常规地表水处理厂。,Profession-related English,Profession-related English,Lake,Chlorine: to establish residual,Intake with screen,Chlorine: for disinfection as necessary,Activated carbon: as necessary for taste and odor control and color removal,Mixing tank,Auxiliary chemicals: to aid coagulation as necessary,Sand filter,Activated carbon: as necessary for taste and odor control,Sodium fluoride: for fluoridation,sedimentation,Fig.2-3 Conventional treatment plant for surface-water with taste and odor problem,Settling filter,Flocculation,Alum: for coagulation,Flocculation,Filtration of nonsettled floc,氯化：根据需要而消毒,活性炭：根据需要去除嗅味和色度,铝：为了絮凝而投放,助凝剂：根据需要添加,絮凝,活性炭：根据嗅味去除的需要,沉淀,氟化钠：氟化处理,未沉淀絮体的过滤,加氯：并保持一定残留,Since then the lake-water source has become increasingly eutrophic, and additional facilities for taste and odor control have been provided. 自从湖泊水源变得富营养化以来,处理厂增加了针对嗅味和色度的处理设施.,Profession-related English,Activated carbon, chlorine dioxide, and various auxiliary chemicals（主语） for improved chemical treatment are now available（谓语） to the operator during critical periods of poorer raw-water quality. 在水源水质较差的紧急时期,活性炭、二氧化氯和其它辅助的化学品在改善化学处理方面是操作人员可以使用的措施。,Profession-related English,During most of the year the finished water is very palatable, but tastes and odors cannot be completely removed during spring and fall lake overturns. 一年中大多数时间里，水厂的处理水质量都好，但在春季和秋季湖水翻塘的时候，嗅味就不能完全去除。,Profession-related English,For a turbid and polluted river with highly variable quality, a complex, flexible treatment system should be employed. 对于浑浊的被污染的河流，其水质变异大，需要复杂和灵活多变的处理系统。,Profession-related English,A general treatment scheme consists of plain sedimentation for desilting; 为了避免被淤塞，一般的处理流程包括自然沉淀。 mixing following by sedimentation, suing coagulants as necessary; 混合紧接在沉淀之后，同时按照需要加入絮凝剂。,Profession-related English,split treatment for partial