环境工程专业英语unit.ppt
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1、Unit 7 Selection of Water Treatment ProcessesProfession-related Englishl 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.l 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。l Behind an intake structure,there com
2、es water treatment process(倒装结构).l 在取水工程后面,是水处理过程。Profession-related EnglishProfession-related Englishl Current pretreatment processes in municipal water treatment are screening,presedimentation or desilting,chemical addition,and aeration.l 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。l Presedimentation is regu
3、larly used to remove suspended matter from river water.l 预沉淀习惯上用于从河水中去除悬浮物。l 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
4、concentrations.l 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 Englishl Conventional chemicals used with presedimentration are the polyelectrolytes and alum.l 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 Englishl Aeration is customarily the first step in treatment for
5、 the removal of iron and manganese from well waters and a standard way to separate dissolved gases such as hydrogen sulfide and carbon dioxide.l 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 Englishl Treatment processes used
6、in water plants depend on the raw-water source and quality of finished water desired.l 水厂使用的处理工艺依赖于原水水源和对处理水的期望。l The specific chemicals selected for treatment are based on their effectiveness to perform the desired reaction and cost.l 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 Englishl For exampl
7、e,activated carbon,chlorine,chlorine dioxide,and potassium permanganate are all used for taste and odor control.l 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 Englishl Excess chlorination,although least expensive,can create undesired trihalomethanes;activated carbon is the most effective chemical.
8、l 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 Englishl 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.l 在地表水处理厂,加药装置常常能用来投加两种或三种
9、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 Englishl There is no fixed rule for color removal applicable to all waters.l 没有适用于所有水的固定的色度去除法则。l Alum coagulation with adequate pretreatment,and applying oxidizing chemicals or activated carbon,may provide satisfactory removal.l 经过足够的预处理后使用铝絮凝剂、应用有
10、氧化作用的化学品或活性炭,可以提供满意的去除。Profession-related Englishl On the other hand,a more expensive coagulant might(be?)prove to be more effective and reduce overall chemical costs.l 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。l Perhaps the most important consideration in designing water treatment processes is to provide
11、flexibility.l 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 Englishl The operator should have the means to change the point of application of certain chemicals.l 操作工应当有办法调节投加特定药剂的点。l For example,chlorine feedlines are normally provided for pre-,intermediate-,and postchlorination.l 例如,加氯的投药管线通常设置成
12、可满足预氯化、中氯化和后氯化的要求。Profession-related Englishl Multiple chemical feeders and storage tanks should be supplied so that various chemicals can be employed in the treatment process.l 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 Englishl Degradation of the raw-water quality,or changes in costs of
13、 chemicals,may dictate a change in the type of coagulant or auxiliary chemicals used in coagulation.l 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 Englishl In the case of(在情况)surface-water treatment plants it is desirable to provide space for the construction of additional pretreatment
14、 facilities.l 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 Englishl The flow in river may change due to construction of dams,channel improvements,or upstream water use.l 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。l The quality of water changes due to human alteration and occupation of the watershed.l 由于人类在流
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