环境科学专业外语Unit-13.ppt
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1、Unit 13Unit 13 Text Text:Water Treatment Water Treatment ProcessesProcesses自来水处理过程nOne of the great achievements of modern technology has been to drastically reduce the incidence of waterborne of diseases such as cholera and typhoid fever.n 现代化技术所取得的伟大成就之一就是极大的降低了霍乱和伤寒等水源性疾病的发生。nThese diseases are n
2、o longer the great risks to pubic health that they once were. n这些疾病曾经对人类的健康产生过巨大威胁,但现在不是了。nThe key to this advance was the recognition that contamination of pubic ware, supplies by human wastes was the main source of infection,and that it could be eliminated by more effective water treatment and bet
3、ter waste disposal. n进步的关键在于人们认识到被人为污染的公共水供应是主要的传染源,这可以通过更积极更先进的水处理技术所消除。nTodays water treatment plants are designed to provide water continuously that meets drinking water standards at the tap. n今天的水处理厂被设计为能持续的提供符合饮用水标准的水。nThere are four man considerations involved in accomplishing this:sour select
4、ion, protection of water quality,treatment methods to be used,and prevention of recontamination.n有四个主要的方面要考虑:水源的选择、水质的保护、所使用的处理方法和如何防止二次污染。nCommon precautions to prevent groundwater and surface water pollution include prohibiting the discharge of sanitary and storm sewers close to the water reservoi
5、r, 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.n一般的预防地下水污染和地表水污染的措施包括防止排泄物管道和雨水管道的排放口靠近蓄水池,安装栅栏防止娱乐用水的污染,限制在水库流域使用化肥和杀虫剂。nScreening,coagulation/flocculation,sedimentatio
6、n, filtration,and disinfection are the main unit operations involved in the treatment of surface water.n隔离、混凝/絮凝、沉淀、过滤是地表水处理的四个主要步骤。n Water treatment operations fulfill one or more of three key tasks: removal of particulate substances such. as sand and clay,organic matter, bacteria,and algae;removal
7、 of dissolved substances such as those sing color and.Hardness; and removal or destruction of pathogenic bacteria and viruses.n水处理要实现一到三个目标:去除沙和尘土等颗粒物质、有机物质、微生物和藻类;去除引起色度和硬度的溶解物质;去除或破坏致病细菌和病毒。n The actual selection of treatment processes depends on the type of water source and the desired water qual
8、ity.n实际的处理工艺的选择有赖于水源的类型和所需要的水质。nOccasionally,raw water with low turbidity can be treated by plain sedimentation (no chemicals) to remove larger particles and then filtration to remove the few particles that failed to settle out. n有时,不太混浊的进水可以通过自然沉降来去除较大的颗粒,在利用过滤去除剩余的颗粒。nUsually, however, particles i
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- 环境 科学 专业 外语 Unit 13