英语翻译(重要)讲述.doc

As pollutants enter air, water, or soil, natural processes such as dilution, biological conversions, and chemical reactions convert waste material to more acceptable forms and disperse them through a larger volume. Yet those natural processes can no longer perform the cleanup alone .The treatment facilities designed by the environmental engineer are based on the principles of self-cleansing observed in nature, but the engineered processes amplify and optimize the operations observed in nature to handle larger volumes of pollutants and to treat them more rapidly. Engineers adapt the principles of natural mechanisms to engineered systems for pollution control when they construct tall stacks to disperse and dilute air pollutants, design biological treatment facilities for the removal of organics from waste water, use chemicals to oxidize and precipitate out the iron and manganese in drinking-water supplies, or bury solid wastes in controlled landfill operations. 当污染物进入空气、水或土壤稀释等自然过程,生物转换,和化学反应将废弃物转化为更容易接受的形式和驱散他们通过一个更大的体积。然而这些自然过程不再单独执行清理。环境工程师的处理设施设计是基于自我观察到自然的原则,但设计过程放大和优化操作中观察到的自然处理更大的大量的污染物和对待他们更迅速。工程师适应自然机制的原则为污染控制工程系统构造高时栈分散和稀释空气污染物,设计生物处理设施去除有机物的废水,使用化学氧化和沉淀铁和锰的饮用水供应,或埋葬在控制固体废物填埋操作 在所有情况下,治疗的最终产品受污染的水或空气或固体废物的处置必须兼容现有的环境资源和水圈的同化力量,不过气氛,或岩石圈。在结构工程,工程师可以简单地指定一个携带较重的负载更大或更强的基础。环境工程师,另一方面,必须接受承载能力f流,一个气流量,或者一个大陆,因为这些很少能被改变Sewage is the wastewater released by residences, businesses and industries in a community. It is 99.94 percent water, with only 0.06 percent of the wastewater dissolved and suspended solid material. The cloudiness of sewage is caused by suspended particles which in untreated sewage ranges from 100 to 350 mg/l. A measure of the strength of the wastewater is biochemical oxygen demand, or BOD5. The BOD5 measures the amount of oxygen microorganisms require in five days to break down sewage. Untreated sewage has a BOD5 ranging from 100 mg/l to 300 mg/l. Pathogens or disease-causing organisms are present in sewage. Coliform bacteria are used as an indica