9环境工程专业英语unit1415

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1、环境科学与工程专业英语环境科学与工程专业英语Specialized English for environmental science and engineeringPART 3 WATER AND WASTEWATER TREATMENTUnit 14 Water PurificationUnit 15 Water Treatment Processesv screening skri:ni v.筛（煤、矿石等） n.放映，播放；筛查 vcoagulationvflocculation vSedimentationsedimentation basin 沉淀池vfiltrationfiltr

2、ein n.过滤；滤除过滤；滤除 vdisinfectionu New Words and PhrasesvCoagulation kju len n.凝结，凝结物 vcoagulate vt.& vi. 凝固；使结块，使变稠 adj. 凝固的，凝结的，凝聚的 vcoagulantk gjlnt n. 凝结剂 沉淀物沉淀物 precipitate; deposition; sediment; sedimentation; subsidence浓缩浓缩,冷凝冷凝 condense; condensation vcolloidal k lidl adj. 带相同电荷的胶粒不能紧密靠近，它们不能聚集

3、成较大的颗粒。 Similarly charged colloidal particles cannot come together closely to agglomerate into larger particles.vcolloid klid n.colloid gold 胶态金 水体所含物质主要有：悬浮物、胶体物质等等。 vMain substances contained in raw waters are suspensions, colloid substances, etc .vdesalinationdi:sli nein 脱盐作用，去盐作用 vsaline seili:n

4、 含盐的；盐水 vsalinitys linti n.盐分，盐度；盐浓度；盐份Physical物理方法物理方法vSedimentation(Clarification) 沉淀沉淀vScreening 格栅格栅uAeration 曝气曝气uFiltration 过滤过滤uFlotation and Skimming 浮选浮选uDegasification 脱气脱气uEqualization 均和均和u Background IntroductionChemical化学方法化学方法vChlorination 氯化氯化vOzonation 臭氧处理臭氧处理vNeutralization 中和中和uC

5、oagulation 絮凝絮凝uAdsorption 吸附吸附uIon Exchange 离子交换离子交换Biological生物方法生物方法vAerobic 好氧法好氧法vActivated Sludge Treatment Method 活性污泥法活性污泥法vTrickling Filtration 滴滤法滴滤法vOxidation Ponds 氧化塘氧化塘uLagoons 泻湖泻湖(氧化塘氧化塘)uAerobic Digestion 需氧消化需氧消化uAnaerobic 厌氧法厌氧法uAnaerobic Digestion 厌氧消化厌氧消化uSeptic Tanks 化粪池化粪池Wate

6、r treatment for domestic and commercial usesCriteriaCausing PollutantCorresponding removal measuresFree of odorOdorous gasesAeration to remove odor gasesFree of turbidity ParticlesAddition of Fe3+ and Al3+ to trap particlesLow BODOrganic materialsBacteria metabolismLow nutrient loadingDissolved N, P

7、 inorganic Chemical precipitationNH3 strippingFree of disease causing agentsmicroorganismsAddition of disinfectantsPrimary water treatmentvPrimary treatment: Remove solids by screening and settling The sewage is passed through a screen to remove large pieces of debris (e.g. sticks, stones, rags, and

8、 plastic bags).Next, the sewage enters a grit chamber, where the water flow is slowed just enough to allow coarse sand and gravel to settle out on the bottom.Water then enters the sedimentation tank, its flow rate is further decreased to permit suspended solids to settle out as raw sludge.Primary wa

9、ter treatment (Continued)vCa(OH)2 and Al2 (SO4)3 are often added to speed up the sedimentation process.3 Ca(OH)2 + Al2(SO4)3 2 Al(OH)3 + 3 CaSO4Al(OH)3 is a gelatinous precipitation that settles out slowly, carrying suspended material and bacteria with it.vOily material floats to the surface and is

10、skimmed off.vThe grit is collected and disposed in landfill.vThe raw sludge:Old way: incinerated, disposed in landfill or dumped at sea.New way: composted to produce a nutrient rich bacteria-free material for use as fertilizer.Primary treatmentIn older sewage-treatment plants, the water after primar

11、y treatment is often chlorinated to kill pathogens and then discharged into a natural waterway.The discharged water at this stage still contains a large amount of oxygen-consuming wastes, which may deplete dissolved oxygen in the water way and cause eutrophication. Secondary treatmentvSecondary trea

12、tment, also called biological treatment: Use bacteria to break down organic compounds to CO2. A mixture of organisms termed activated sludge is added to the sewage effluent.Air or oxygen is vigorously bubbled through pipes into the effluent.The aerobic bacteria digest the organic material and break

13、it down into CO2 and water. The bacteria and any remaining undecomposed material are returned to the aeration tank and reused.Activated sludge processSecondary treatment of municipal wastewaterMost municipal plants chlorinated the water after secondary treatment and then release it into waterways.Th

14、e discharged water at this stage has 90% of the original organic matter removed, but over 50% of N, P species remains, and metal ions and many synthetic organic compounds are incompletely removed. (eutrophication )Tertiary treatmentvRemove N and P nutrients.P removal by precipitation with lime 3 PO4

15、3- + CaO (lime) Ca5(PO4)3(OH)Phosphate can also be removed by microorganisms that absorb phosphate.NH4+ removal by ammonia stripping.NH4+ + OH- = NH3 + H2O (Excess OH- from lime)Alternative NH4+ removal: nitrifying bacteria convert NH4+ to NO3- followed by denitrifying bacteria to convert NO3- to N2

16、. vRemove organics through filtration by activated carbonTertiary treatment, also called advanced waste treatment, includes a variety of processes performed on the effluent from secondary waste treatment.HydroxyapetiteTertiary treatment of municipal wastewaterPerformance of primary and secondary sta

17、ges of sewage treatmentPollutants RemovedComponent removedPrimary treatmentSecondary treatmentBiological oxygen demand30%90%Suspended solids60%90%Nitrogen compounds20%50%Phosphorus compounds10%30%Source: American Chemical SocietySludge disposalvSludge is an excellent fertilizer in principle: rich in

18、 organic material and nutrients.vSludge often contains toxic metal species, which restricts the application of sludge to cropland.vSludge can be a low-quality fuel for generating electricity.vSludge could be converted to methane by anaerobic bacteria, but this option suffers poor economics.Disinfect

19、ionvCommon disinfectants: Cholrine, chlorine dioxide, and ozone.vDisinfectants kill microorganisms by oxidizing vital molecules (often with unsaturated carbon bond) in them.Cl2 + H2O = HClO + H+ + Cl-Hypochlorous acidActive disinfection componentPros and cons of various disinfectantsvCl2: Cl2 is eff

20、ective and relatively cheap.HClO can act as a chlorinating agent to produce a variety of chlorinated organic compounds (for example, CHCl3).Many of the Cl-containing organics are toxic and non-biodegradable. Some (e.g. CH2Cl2, CHCl3, C2HCl3) are suspected carcinogens.vO3 and ClO2: More expensive tha

21、n Cl2.Need to be generated on-site add on to the capital cost.Fast-acting and rapidly decomposed. vImpurities in water were classified as suspended, colloidal, or dissolved. 水中的杂质可分为悬浮的，胶体态的或溶解态的。水中的杂质可分为悬浮的，胶体态的或溶解态的。 colloidal k lidl adj. colloid klid n. colloid gold 胶态金 带相同电荷的胶粒不能紧密靠近，它们不能聚集成较大的颗

22、粒。 Similarly charged colloidal particles cannot come together closely to agglomerate into larger particles.u TextvOne possibility is somehow to make these small particles join together to become larger ones, which can then be treated as suspended matter. Another possibility is to convert them to a g

23、as that escapes from the water into the atmosphere. v（去除去除它它们的们的）一个可能的方法是以某种方法把这些一个可能的方法是以某种方法把这些微小的颗粒物结合成比较大的颗粒然后采用去除悬浮微小的颗粒物结合成比较大的颗粒然后采用去除悬浮物的方法来处理。另一种可能的方法是把他们转变为物的方法来处理。另一种可能的方法是把他们转变为气态气态，从水中从水中排放排放到大气中到大气中。u TextvWaterborne wastes from sources such homes, hospitals, and schools contain food r

24、esidues, human excrement, paper, soap, detergents, dirt, cloth, other miscellaneousmslens debris, and, of course, microorganisms. v水中的废物有各种各样的来源，例如家庭的，医院的，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，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，当然还有清洁剂，脏物，布，其他各种各样的杂物，当然还有微生物。微生物。u TextvThe combined

25、 piping is cheaper and is adequate in dry weather, but during a storm the total volume is apt to exceed the capacity of the treatment plant, so some allowed to overflow and pass directly into the receiving stream or river.v结合的网络式是比较便宜的，而且适合干燥的天气，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，但在暴雨时，总

26、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或江河所以某些水就允许溢流出去和直接排放到河流或江河里面去。里面去。u TextvWhen the sewage reaches the treatment plant, it first passes through a series of screens that remove large objects such as rats or grapefruita, and then through a grinding mechanism that reduces any remaining objects to a

27、size small enough to be handled effectively during the remaining treatment period. v当污水进入处理厂时，首先通过一系列的筛网以去除当污水进入处理厂时，首先通过一系列的筛网以去除其中大的物体如老鼠或葡萄柚，然后通过一个磨碎装其中大的物体如老鼠或葡萄柚，然后通过一个磨碎装置以便把剩余的物体的大小减小至足够小以至在后续置以便把剩余的物体的大小减小至足够小以至在后续的工艺中可以有效的处理。的工艺中可以有效的处理。u TextPrimary TreatmentsvThe next stage is a series of

28、 settling chambers designed to remove 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.v下一步是一系列的沉淀室用来去除例如雨水冲刷路面下一步是一系列的沉淀室用来去除例如雨水冲刷路面带入的沙粒等重的粗沙带入的沙粒等重的粗沙

29、, 然后其他悬浮的固体然后其他悬浮的固体-包括在包括在大约大约一个小时能沉淀下来的有机营养物，一个小时能沉淀下来的有机营养物，更缓慢的沉更缓慢的沉淀而得到去除。淀而得到去除。u TextvUp to this point the entire process, which is called primary treatment, has been relatively inexpensive but has not accomplished much.v从开始到这个过程的整个工艺称为初级处理，这一级从开始到这个过程的整个工艺称为初级处理，这一级处理的费用相对低，但是没有完成多少任务。处理的费用

30、相对低，但是没有完成多少任务。u TextvThe next series of steps is designed to reduce greatly the dissolved or finely suspended organic matter by some form of accelerated biological action. v接下来的一系列步骤是接下来的一系列步骤是企图通过某些强化的生物作用企图通过某些强化的生物作用来来较大程度地较大程度地减少溶解态或细小的悬浮有机物质。减少溶解态或细小的悬浮有机物质。vWhat is needed for such decompositi

31、on is oxygen and organisms and an environment in which both have ready access to the nutrients. v分解有机物需要氧气和生物体及有利于提供营养的环分解有机物需要氧气和生物体及有利于提供营养的环境（一种两者都易接近营养物的环境）。境（一种两者都易接近营养物的环境）。u TextSecondary TreatmentsvIn this device, long pipes rotate slowly over a bed of stones, distributing the polluted water

32、 in continuous sprays. As the water trickles over and around the stones, it offers its nutrients in the presence of air to an abundance of rather unappetizing forms of life.v在此装置中，长的管子缓慢绕着石头滤床旋转在此装置中，长的管子缓慢绕着石头滤床旋转(回转布回转布水器水器)，通过持续喷洒使污水均匀分布。当污水以水滴，通过持续喷洒使污水均匀分布。当污水以水滴流过石头滤料时，在有氧的情况下向大量的没有驯化流过石头滤料时，在

33、有氧的情况下向大量的没有驯化过的生物体提供了营养。过的生物体提供了营养。u Text One device for accomplishing this objective is the trickling filter. 滴滤池滴滤池vAn alternative technique is the activated sludge process. Here the sewage, after primary treatment, is pumped into an aeration tank, where it is mixed for several hours with air and

34、 bacteria-laden sludge. v另一种方法是活性污泥法。在这里，污水在经过初级另一种方法是活性污泥法。在这里，污水在经过初级处理后被泵到一个处理后被泵到一个曝气池曝气池中，然后与空气及含有细菌中，然后与空气及含有细菌的污泥混合几个小时。的污泥混合几个小时。u TextvThe treated waters then flow to a sedimentation tank, where the bacteria-laden solids settle out and are returned to the aerator. v经二级处理过的水流入沉淀池，在那里充满细菌的污经二

35、级处理过的水流入沉淀池，在那里充满细菌的污泥沉淀下来然后回流到通风装置中。泥沉淀下来然后回流到通风装置中。u TextvSince the microorganisms have done their work, they may now be killed. The final step is therefore a disinfection process, usually chlorination, Chlorine gas, injected into the effluent 15 to 30 minutes before its final discharge, can kill

36、more than 99 percent of the harmful bacteria.v因为微生物完成其工作，现在就可以杀死他们了。最因为微生物完成其工作，现在就可以杀死他们了。最后一步是消毒过程，一般是加氯。氯气，在最后排放后一步是消毒过程，一般是加氯。氯气，在最后排放前加入到排水前加入到排水15至至30分钟，就可以杀灭分钟，就可以杀灭99%以上的有以上的有害细菌。害细菌。u TextvAlthough considerable purification is accomplished by the time wastewaters have passed through the pri

37、mary and secondary stages, these treatments are still inadequate to deal with some complex aspects of water pollution.v尽管此时的废水尽管此时的废水经过初级处理和二级处理后已经在很经过初级处理和二级处理后已经在很大程度上得到了净化大程度上得到了净化，但是这些处理方法在应对某些，但是这些处理方法在应对某些水污染的复杂方面仍然是不够的。水污染的复杂方面仍然是不够的。u TextTertiary or “Advanced” TreatmentsTertiary or “Advance

38、d” TreatmentsCoagulation and Sedimentation2. Adsorption3. Other Oxidizing Agents4. Reverse OsmosisvVarious 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 se

39、ttle out in a reasonable time. This process is called flocculation. Lime, alum, and some salts of iron are among these so-called flocculating agents.v各种各样的无机胶体颗粒是喜欢水的（亲水的）并且各种各样的无机胶体颗粒是喜欢水的（亲水的）并且因此因此具有相当的粘附性；由于它们的粘附性它们一起具有相当的粘附性；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带走很多其他难以在合理时间内沉降下来的胶体颗粒物。这个过程被称为絮凝。

40、石灰，矾和某些铁盐都是物。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。这些所谓的絮凝剂。u TextvAdsorption is the process by which molecules of a gas or liquid adhere to the surface of a solid.v吸附是气体分子或液体分子粘附到固体表面的过程。吸附是气体分子或液体分子粘附到固体表面的过程。vTo purify water, a solid that has a large surface area and binds preferentially to organic pollu

41、tants is needed. The material of choice is activated carbon, which is particularly effective in removing chemicals that produce offensive tastes and odors. These include the biologically resistant chlorinated hydrocarbons.v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。选择的物质是活性碳，它能够特别

42、有效地除的固体是必需的。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物质。这些化学物质包括去产生令人讨厌的味道和臭味的化学物质。这些化学物质包括那些难以生物降解的氯代烃。那些难以生物降解的氯代烃。u TextvPotassium permanganate (KMnO4) and ozone (O3) have been used to oxidize waterborne wastes that resist oxidation by air in the presence of microorganisms. v高锰酸钾和臭氧已被用来氧化水中的不易被存在于水高锰酸钾

43、和臭氧已被用来氧化水中的不易被存在于水中的微生物在有氧的条件下氧化的污染物。中的微生物在有氧的条件下氧化的污染物。u TextvOsmosis is the process by which water passes through a membrane that is impermeable to dissolved ions. In the normal course of osmosis, the system tends toward an equilibrium in which the concentrations on both sides of the membrane are

44、 equal. v渗透是指水可以通过膜而其他溶解性的离子却不可以渗透是指水可以通过膜而其他溶解性的离子却不可以通过膜的这种过程。在渗透的正常过程中，该体系趋通过膜的这种过程。在渗透的正常过程中，该体系趋向于使膜的两侧的浓度达到平衡。向于使膜的两侧的浓度达到平衡。u TextvHowever, if excess pressure is applied on the concentrated side, the process can be reversed, and the pure water is squeezed through the membrane and thus freed o

45、f its dissolved ionic or other soluble pollutants.v但是如果在高浓度一侧施加超过正向动力的压力，这但是如果在高浓度一侧施加超过正向动力的压力，这个过程可以颠倒过来（水分子的流动方向会改变），个过程可以颠倒过来（水分子的流动方向会改变），因此污水中的纯水会被挤压通过膜而使溶解态的离子因此污水中的纯水会被挤压通过膜而使溶解态的离子及其他可溶污染物得到分离。及其他可溶污染物得到分离。u TextvVarious inorganic colloidal particles are waterloving (hydrophilic) and theref

46、ore rather adhesive; in their stickiness they sweep together many other colloidal particles that would otherwise fail to settle out in a reasonable time.v许多无机胶体颗粒是亲水性的，因此粘性较大；在它许多无机胶体颗粒是亲水性的，因此粘性较大；在它们吸附水分子过程中又会席卷许多其他胶体颗粒们吸附水分子过程中又会席卷许多其他胶体颗粒,而这而这些胶体颗粒自身不能在合理（较短的）时间内沉淀下些胶体颗粒自身不能在合理（较短的）时间内沉淀下去。去。u T

47、extvHowever, if excess pressure is applied on the concentrated side, the process can be reversed, and the pure water is squeezed through the membrsne and thus freed of its dissolved ionic or other soluble pollutants.v可是可是,如果在污水一侧施加多余的压力，水的流动方向如果在污水一侧施加多余的压力，水的流动方向会改变，纯水分子会被挤压通过膜而使溶解态的离子会改变，纯水分子会被挤压通

48、过膜而使溶解态的离子及其他可溶性污染物得到分离及其他可溶性污染物得到分离.u TextPART 3 WATER AND WASTEWATER TREATMENTUnit 15 Water Treatment Processesv The key to this advance was the recognition that contamination of public water supplies by human wastes was the main source of infection, and that it could be eliminated by more effecti

49、ve water treatment and better waste disposal. v其发展的关键在于认识到人类废弃物对公共供水的污其发展的关键在于认识到人类废弃物对公共供水的污染是主要传染源，并且这种污染可以通过更有效的水染是主要传染源，并且这种污染可以通过更有效的水处理工艺和更好的废水处置方法来消除。处理工艺和更好的废水处置方法来消除。u TextvThere are four main considerations involved in accomplishing this: source selection, protection of water quality, trea

50、tment methods to be used, and prevention of recontamination.v达到这个目的涉及到四个重要问题：水源的选择、水达到这个目的涉及到四个重要问题：水源的选择、水质的保护，工艺方法的使用以及再污染的防治。质的保护，工艺方法的使用以及再污染的防治。 u TextvCommon precautions to prevent groundwater and surface water pollution include prohibiting the discharge of sanitary and storm sewers close to t

51、he water reservoir, installing fences to prevent pollution from recreational uses of water, and restrictions on the application of fertilizers and pesticides in areas that drain to the reservoir.而阻止地下水和地表水污染常用的预防措施是，禁止而阻止地下水和地表水污染常用的预防措施是，禁止排放生活排污和雨水的下水道接近蓄水池，安装栅栏排放生活排污和雨水的下水道接近蓄水池，安装栅栏以防止娱乐用水被污染，还有

52、就是在会向水库排水的以防止娱乐用水被污染，还有就是在会向水库排水的区域限制使用肥料和农药。区域限制使用肥料和农药。u TextvScreening, coagulation/flocculation, sedimentation, filtration. and disinfection are the main unit operations involved in the treatment of surface water. v隔离、混凝隔离、混凝/絮凝、沉淀、过滤和消毒是地表水絮凝、沉淀、过滤和消毒是地表水处理涉及到的主要单元操作。处理涉及到的主要单元操作。u TextvWater t

53、reatment operations fulfill one or more of three key tasks: removal of particulate substances such as sand and clay, organic matter, bacteria, and algae; removal of dissolved substances such as those causing color and hardness; and removal or destruction of pathogenic bacteria and viruses. v水处理工艺实现了

54、一个或者多达三个主要任务：除去细水处理工艺实现了一个或者多达三个主要任务：除去细小的颗粒物，如沙粒和泥土、有机物质、细菌，还有藻小的颗粒物，如沙粒和泥土、有机物质、细菌，还有藻类；除去溶解性物质，如一些引起色度和硬度的物质；类；除去溶解性物质，如一些引起色度和硬度的物质；还有就是除去或者破坏致病菌和病毒。还有就是除去或者破坏致病菌和病毒。u Textv To remedy this, a chemical is added to coagulate/flocculate the small particles, called colloids, into large ones, which c

55、an then be settled out in sedimentation tanks or removed directly in filters.v为了弥补这一点，加入化学药品以混凝为了弥补这一点，加入化学药品以混凝/絮凝这些小的絮凝这些小的胶体颗粒，使其形成可以在沉淀池内沉降或者可以被胶体颗粒，使其形成可以在沉淀池内沉降或者可以被过滤器直接去除的较大颗粒物。过滤器直接去除的较大颗粒物。u TextvScreening to remove large solids such as logs, branches, rags, and small fish is the first sta

56、ge in the treatment of water. v阻隔是指去除木块、树枝、碎屑和小鱼等类似物的固阻隔是指去除木块、树枝、碎屑和小鱼等类似物的固体物。它是污水处理的第一阶段。体物。它是污水处理的第一阶段。vSedimentation, the oldest and most widely used form of water and wastewater treatment, uses gravity settling to remove particles from water.v沉淀是最古老也是应用最广泛的水处理方法。它是利沉淀是最古老也是应用最广泛的水处理方法。它是利用自由沉淀

57、去除水中颗粒物。用自由沉淀去除水中颗粒物。vSedimentation, precipitation，settle outu TextvParticulates suspended in surface water can range in size from 10-1 to10-7 mm in diameter, the size of fine sand and small clay particles, respectively. Turbidity or cloudiness in water is caused by those particles larger than 10-4

58、mm, while particles smaller than 10-4 mm contribute to the color and taste.v地表水悬浮物颗粒物直径在地表水悬浮物颗粒物直径在10-110-7毫米之间变化。毫米之间变化。这个尺寸正好也是微小沙粒和细小粘土颗粒各自的大这个尺寸正好也是微小沙粒和细小粘土颗粒各自的大小。引起水浊度的颗粒物直径在小。引起水浊度的颗粒物直径在10-4毫米以上，而毫米以上，而10-4毫米以下的颗粒影响水的色度和味道。毫米以下的颗粒影响水的色度和味道。u TextvCoagulation/flocculation is a chemical-phys

59、ical procedure whereby particles too small for practical removal by plain sedimentation are destabilized and clustered together for faster settling.v混凝混凝/絮凝是一个化学物理过程，那些太小的用普通沉絮凝是一个化学物理过程，那些太小的用普通沉降法不能去除的颗粒通过这个过程失去稳定性能聚集降法不能去除的颗粒通过这个过程失去稳定性能聚集成团，从而能较快地沉淀成团，从而能较快地沉淀.u TextvCoagulation is s chemical pr

60、ocess used to destabilize colloidal particles. The exact mechanism is not well understood, but the general idea is to add a chemical which has positively charged colloids to water containing negatively charged colloids. v混凝是使胶体颗粒变得不稳定的化学过程。确切机理混凝是使胶体颗粒变得不稳定的化学过程。确切机理并未完全探究清楚，但是大致是向含有负电荷的胶体并未完全探究清楚，但

61、是大致是向含有负电荷的胶体的水中加入能形成正电荷胶体的化学物质。的水中加入能形成正电荷胶体的化学物质。vThis will neutralize the negative change on the colloids and thus reduce the tendency for the colloids to repel each other.v这将会中和胶体表面的负电荷从而减少胶体之间相互这将会中和胶体表面的负电荷从而减少胶体之间相互排斥的趋势。排斥的趋势。u Textv Gentle mixing, called flocculation, of the suspension is t

62、hen undertaken to promote particle contact. This is achieved by mechanical mixing through the use of slowly rotating paddles inside the coagulation/flocculation tank, or by hydraulic mixing which occurs when flow is directed over and around baffles in the tank. v悬浮物的慢速混合称为絮凝，可以促进颗粒间的接触。悬浮物的慢速混合称为絮凝，

63、可以促进颗粒间的接触。这可以在混凝这可以在混凝/絮凝池内通过使用慢速旋转桨进行机械絮凝池内通过使用慢速旋转桨进行机械混合来实现，或利用水流直接在池内折流板周围形成混合来实现，或利用水流直接在池内折流板周围形成的水压混合。的水压混合。u Textv Through the combined chemicsl/physical process of coagulation/flocculation, the colloidal particles which would not settle out by plain sedimentation are agglomerated to form l

64、arger solids called floc. v通过混凝通过混凝/絮凝联合的化学絮凝联合的化学/物理过程，不能被简单沉降物理过程，不能被简单沉降池沉降的胶体颗粒可以聚集形成一种大颗粒状的絮状池沉降的胶体颗粒可以聚集形成一种大颗粒状的絮状物。物。u TextvOzonation, which has been used extensively in France, is now gaining acceptance in North America, especially as an alternative to prechlorination where natural organics

65、 are present. v在法国已经被广泛应用的臭氧氧化方法，特别是在天然在法国已经被广泛应用的臭氧氧化方法，特别是在天然有机物存在的情况下可以作为预加氯的替代品，现在正有机物存在的情况下可以作为预加氯的替代品，现在正在北美获得认可。在北美获得认可。u TextvOzoanation is the disinfection of water by adding ozone, which is a powerful oxidant of inorganic and organic impurities. Its advantages over chlorine are that it lea

66、ves no tastes or odors, and unlike chlorine, it apparently does not react with natural organics to form compounds hazardous to humans.v臭氧氧化是指加入臭氧对水消毒，臭氧是无机和有机杂臭氧氧化是指加入臭氧对水消毒，臭氧是无机和有机杂质的强氧化剂。臭氧和氯气比较起来优越性在于它不会质的强氧化剂。臭氧和氯气比较起来优越性在于它不会留下味道和气味，而且臭氧显然不会像氯气一样和天然留下味道和气味，而且臭氧显然不会像氯气一样和天然有机物反应生成对人体有害的化合物。有机物反应生成对人体有害的化合物。u TextvAeration is used to remove excessive amounts of iron and manganese from groundwater. These substances cause taste and color problems, interfere with laundering, stain plumbing fixt