《给水排水专业英语课件(李田)7.》由会员分享，可在线阅读，更多相关《给水排水专业英语课件(李田)7.（28页珍藏版）》请在金锄头文库上搜索。
1、Unit 7 Selection of Water Treatment Processes 1 New words and expressions nwatershed n. 流域 分水岭 nscreen n. 筛子 vt. 筛分 npresedimentation n. 预沉降 ndesilt v. 挖除淤泥 沉砂 npretreat vt. 预先处理,预处理 ncoagulation n. 混凝 coagulant 混凝剂 nbacterial adj. 细菌的bacterium n. 细菌 pl. bacteria. npolyelectrolyte pliilektrulait n.
2、聚合(高分子)电解质 nalum n. 明矾, 矾 aluminium 铝 nsulfide n. 硫化物 nhydrogen sulfide ntaste and odor 嗅味 nchlorine n. 氯气 氯 nchlorine dioxide 二氧化氯 2 New words and expressions npotassium ptsim n. 钾 npermanganate n. 高锰酸 高锰酸盐 ntrihalomethane n. 三卤甲烷 noxidize v. (使)氧化 nflexibility n. 弹性, 适应性, 机动性, 挠性 nfeedline n. 进料管线
3、 nfeeder n. 进料器 投加装置 nland-runoff n. 地表径流 neutrophic ju:trfik adj. 富营养的 nsuppress vt. 镇压 抑制 suppress a smile. naerator n. 通风装置 曝气器 tray aerator nfloc n. 絮凝体 絮状物 nfilter n. 滤池 过滤器 vt. 过滤 3 New words and expressions nammonia n. 氨水 氨 ammonium 铵. amine mi:n , min 胺 nresidual adj. 剩余的 残留的 n. 残留 残余物 nfree
4、 chlorine residual n. 自由性余氯 nCombined chlorine residual n. 化合性余氯 nfluosilicic acid n. 氟硅酸 nmanganese m,ni:s, ,mni:z n. 锰 nlime softening n. 石灰软化 nflocculation n. 絮凝 nfluoride n. 氟化物 nplain sedimentation n. 自然沉淀 简单沉降 nscale n. 结垢 垢层 vi. 生水垢 nrefractory adj. 难降解的 难控制的 难溶的 nshort-circuit vt. 使短 4 nWate
5、rshed management should be considered part of the operation of a water- supply system, which is very important to protect raw water quality. nBehind an intake structure, there comes water treatment process. 1-11-1 5 nCurrent pretreatment processes in municipal water treatment are screening, presedim
6、entation or desilting, chemical addition, and aeration. nScreening is practiced in pretreating surface waters. nPresedimentation is regularly used to remove suspended matter from river water. 2-12-1 6 nChemical treatment, in advance of in-plant coagulation, is most frequently applied to improve pres
7、edimentation, to pretreat hard -to-remove substances, such as taste and odor compounds and color, and to reduce high bacterial concentrations. 2-22-2 7 nConventional chemicals used with presedimentation are the polyelectrolytes and alum. nAeration is customarily the first step in treatment for the r
8、emoval of iron and manganese from well waters and a standard way to separate dissolved gases such as hydrogen sulfide and carbon dioxide. 2-32-3 8 nTreatment processes used in water plants depend on the raw-water source and quality of finished water desired. nThe specific chemicals selected for trea
9、tment are based on their effectiveness to perform the desired reaction and cost. 3-13-1 9 nFor example, activated carbon, chlorine, chlorine dioxide, and potassium permanganate are all used for taste and odor control. nExcess chlorination, although least expensive, can create undesired trihalomethan
10、es; activated carbon is the most effective chemical. 3-23-2 10 nIn 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. 3-33-3 11 nThere is no fixed
11、rule for color removal applicable to all waters. n Alum coagulation with adequate pretreatment, and applying oxidizing chemicals or activated carbon, may provide satisfactory removal. n On the other hand, a more expensive coagulant might prove to be more effective and reduce overall chemical costs.
12、3-43-4 12 nPerhaps the most important consideration in designing water treatment processes is to provide flexibility. nThe operator should have the means to change the point of application of certain chemicals. nFor example, chlorine feedlines are normally provided for pre-, intermediate-, and postc
13、hlorination . 4-14-1 13 nMultiple chemical feeders and storage tanks should be supplied so that various chemicals can be employed in the treatment process. nDegradation of the raw-water quality, or changes in costs of chemicals, may dictate a change in the type of coagulant or auxiliary chemicals us
14、ed in coagulation. 4-24-2 14 nIn the case of surface-water treatment plants it is desirable to provide space for the construction of additional pretreatment facilities. nThe flow in river may change due to construction of dams, channel improvements, or upstream water use. 4-34-3 15 nThe quality of w
15、ater changes due to human alteration and occupation of the watershed. nConcentrations of pollutants from disposal of municipal and industrial wastes and agricultural land-runoff may increase. nLakes can become more eutrophic. 4-44-4 16 17 nThe treatment plant described in Fig. 2-2 is a groundwater p
16、lant with provisions for iron and manganese removal and lime softening. 5-15-1 18 Sand filter Wells Chlorine: to suppress growth of iron bacteria in pipes and initate oxidation of Fe and Mn Chlorine: to oxide reduced Mn remaining Aeration: to increase dissolved oxygen, oxidize Fe and Mn and reduce CO2 Removal of Fe and Mn floc Tray aerator Contact or detection tank Detention: to allow for complete oxidati
