专业英语(给排水与环境工程李田)Unit9选编.ppt

Unit 9Sedimentation —p59;New words and expressions;New words and expressions;Sedimentation or clarification is the removal of particulate matter, chemical floc, and precipitates from suspension through gravity settling. 沉淀和澄清是从悬浮物中通过重力沉降去除颗粒物、化学絮凝产物和凝结沉淀物。 This makes water clarification a vitally important step in the treatment of surface waters for potable supply and in most cases the main factor in determining the overall cost of treatment. 这使得水的澄清是饮用水供应中地表水处理的至关重要一步，在很多情况下，它也是决定全部水处理费用中主要的因素。 Poor design of the sedimentation basin will result in reduced treatment efficiency that may subsequently upset other operations. 糟糕的沉淀池设计将会导致降低处理效率，接下来这也许会影响到其它（水处理工艺）的运行。 ;Surface water containing high turbidity may require sedimentation prior to chemical treatment. 地表水（包含）在高浊度下就要求在化学处理工艺之前沉淀。 Presedimentation basins are constructed in excavated ground or out of steel or concrete. 预沉淀池建在被挖坑的地下或用钢筋混凝土建造。 Steel and concrete tanks are often equipped with a continuous mechanical sludge removal apparatus. 钢筋混凝土池通常装配有持续的机械除泥设施。;The minimum recommended detention time for presedimentation is 3h, although at many times of the year, this may not be adequate to remove fine suspensions. 在预沉池，（被建议）规定的最短停留时间是3小时，尽管在一年的很多时候，这个时间可能不足够去去除细小悬浮物质。 Chemical feed equipment may be provided ahead of presedimentation to provide prechlorination or partial coagulation for periods when water is too turbid to clarify by plain sedimentation. 当通过平流池水太浑浊而不能澄清时，化学药剂投加装置就需要设置在预沉池之前去预加氯或者添加部分的混凝剂。;Settling basins are usually provided for chemical coagulation or softening. 沉淀池通常投加一些混凝剂和软化药剂。 These basins may be constructed of concrete or steel in a wide variety of shapes and flow mechanisms. 这些池子用钢筋混凝土建成各种各样的形状和流动机制。 To minimize the effects of short-circuiting and turbulent flow, care is taken in the effective hydraulic design of inlet and outlet structures in all tanks. 精心的考虑到所有池子进出口结构的水力设计，去最小化短流与紊流的影响。;Inlet structures are expected to: