电子教案与课件：《化工专业英语》Unit11

1、Unit 11 Wastewater Treatment ProcessesHang XuHenan University of Science and TechnologyWastewater treatment is essentially a mixture of settlement and biological or chemical unit processes. 废水处理基本上是沉降和生物或化学单元过程的结合。Treatment plants are assembled from combinations of unit processes, and as the range o

2、f available unit processes is large, by using a suitable combination of the available processes, it is possible to produce a final effluent of a specified quality from almost any type of influent wastewater. 处理设备由单元工艺组合而成，由于可用单元工艺的范围较大，通过将可用工艺的适当组合，几乎任何类型的废水经处理后都有可能变成特定质量的水。Unit treatment processes

3、can be classified as follow.单元处理过程可以分为以下阶段：Screens（1）格栅 Raw sewage enters the plant containing a variety of coarse solids that need to be removed prior to treatment so that pumps are not damaged and pipework is not blocked.原污水进入处理装置时含有各种各样的大颗粒固体物质，在处理之前需要去除这些固体物质，以便泵不会被损坏并且管道不被堵塞。 Screens come in a

4、variety of designs and sizes. 格栅有多种设计和尺寸。Most plants employ simple screens comprising vertical rows of steel bars which can be curved, vertical straight or inclined straight in design, to physically remove such solids from the influent wastewater. 大多数工厂采用具有垂直排的钢条的简单筛网，它可以是弯曲的、垂直的或倾斜的直线设计，以物理处理的方式从流入

5、废水中除去这类固体。Screens are in four sizes, coarse, fine, very fine, or micro. 格栅有四种尺寸，粗、细、非常细或微细。At a small works, a rough design figure for manually-raked screens is 0.14 m2 of submerged areas per 1000 population.在小型设计中，手动格栅的粗略设计是0.14平方米浸没区每1000个孔。Grit separation（2）砂砾分离After screening, the wastewater is

6、termed screened sewage. 在筛选和/或浸渍后，废水称为筛选或浸渍污水。Although it no longer contains gross solids, it does contain a mixture of silt, sand and gravel, as well as fragments of metal, glass and even dense plastic. 虽然它不再含有总固体，但它确实还含矿料、淤泥、砂和砾石的混合物，以及金属、玻璃甚至致密塑料的碎片。They need to be removed from the influent waste

7、water to prevent pump damage and silting. 它们需要从流入的废水中除去，以防止泵损坏和淤塞。Detritors and vortex separators are the most commonly used systems, and both are based on sedimentation.碎屑器和涡流分离器（水力旋流器）是最常用的系统，并且都基于沉降机理。 Detritors are high rate, shallow settlement tanks designed to remove particles of 0.2 mm diamet

8、er with a specific gravity of 2.65 and a settling velocity of 0.02m/s. 碎屑器是高率浅层沉降罐，设计用于去除直径为0.2mm，比重为2.65和沉降速度为0.02ms-1的颗粒。Vortex separators such as the grit trap are very compact.涡流分离器如皮斯塔沉砂池是非常紧凑的。 Waste water enters a vortex shaped tank tangentially and the separation of the grit by centrifugal f

9、orce is assisted by a rotating paddle. 废水切向进入涡流槽，通过离心力的作用和旋转桨叶的辅助作用，砂粒得到分离。Dissolved air flotation（3）溶解气浮Suspended particles that have a specific gravity less than water are removed by allowing them to float to the surface and then be removed by a mechanical skimming device.比重小于水的悬浮颗粒通过气浮到表面然后通过机械撇除

10、装置除去。 Although this is normally done passively during primary sedimentation, it can be assisted by using special units that employ dissolved air or nitrogen.虽然这通常在初沉池阶段进行，但是可以通过采用溶解的空气或氮气的特殊装置来进行辅助。Compressed air is fed into the wastewater and fully mixed. Very small bubbles are formed that attach t

11、o the solid, increasing their buoyancy, and lifting them out of the water to form a thick surface layer of solids known as float.压缩空气进入废水中并完全混合.形成非常小的气泡，附着到固体上，以增加它们的浮力，并将它们从水中提出以形成漂浮絮体厚表面层。 Dissolved air flotation (DAF) units are used primarily to remove emulsified fats, oils and grease (FOG).溶解气浮（

12、DAF）装置主要是用来去除乳化脂肪，油和油脂（FOG）。Chemical flocculants (e.g. polyacrylamide, iron and aluminium salts) are used to enhance DAF performance.化学絮凝剂（例如聚丙烯酰胺、铁和铝盐）用于增强DAF性能。 Where the float is to be used either for animal or human consumption, then natural organic flocculants such as chitosan, carrageenan, lig

13、nosulphonic acid, or their derivatives, are used.当浮体用于动物或人类使用时，则使用天然有机絮凝剂，例如壳聚糖、角叉胶、木质素磺酸或其衍生物。The use of flocculants has allowed DAF systems to replace conventional sedimentation tanks in some industrial applications.絮凝剂的使用使得DAF系统可以在一些工业应用中代替传统的沉淀池。 Both pathogens and micro-pollutants, such as poly

14、chlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH), have a high affinity for particulate matter.病原体和微污染物，如多氯联苯和多环芳烃，对颗粒物具有很高的亲和性。 DAF can be used as either a preliminary or tertiary step to help remove such material.溶解气浮可以用来作为一个初步或第三步处理来帮助去除这种物质。Primary treatment初级处理Primary treat

15、ment or sedimentation is the process by which settleable solids are removed from the screened sewage by passing it through a specially constructed tank at such a velocity that the solids settle out of suspension by gravity. 初级处理或沉淀是指将沉淀性固体从隔筛污水中移除的过程，方法是将其通过一个特别建造的水箱，其速度使固体在重力作用下沉淀出悬浮物。 The settleab

16、le solids collect at the base of the tank where they are removed as primary sludge. 沉淀性固体聚集在水箱底部，作为主要污泥被清除。The retention time in sedimentation tanks is usually a minimum of 2 hours at 3 dry weather flow (DWF) and when operated correctly, can significantly reduce the organic loading to the secondary

17、treatment stage. 在3个干燥气流(dwf)的情况下，沉淀池的停留时间通常最少为2小时，如果操作正确，可显著减少有机负荷至二级处理阶段。Comparing the unit processes, sedimentation is far cheaper than biological treatment in terms of unit removal of pollution and for that reason, the majority of plants have incorporated primary sedimentation into their design.

18、 .比较单元工艺，沉淀比生物处理在单元去除污染方面要便宜得多，因此，大多数工厂都在设计中加入了初级沉淀。Removal of suspended solids is due to a number of processes occurring simultaneously within the sedimentation tank such as flocculation, adsorption, and sedimentation，Maximum removal efficiencies can be as high as 70% for suspended solids and 40% f

19、or BOD5. 除去悬浮固体是由于沉淀池内同时进行多项工序，例如絮凝、吸附和沉淀。最高去除率对悬浮固体高达70% ，对五日生化需氧量高达40% 。Secondary treatment二级处理Secondary treatment is a biological process where the settled sewage enters a specially designed reactor where under aerobic conditions, organic matter in solution is oxidised or incorporated into cells.

20、 二级处理是一种生物过程，其中沉降的污水进入特别设计的反应器，在好氧条件下，溶液中的有机物被氧化或吸入细胞。The reactor provides a suitable environment for the microbial population to develop and as long as oxygen and food, in the form of settled sewage, are supplied then the biological oxidation process will continue.反应器为微生物种群的发展提供了一个合适的环境，只要以沉淀污水的形式提

21、供氧气和食物，生物氧化过程就会继续。Biological treatment is primarily due to bacteria which form the basic trophic level in the reactor food chain. 生物处理主要是由于在反应堆食物链中形成基本营养级的细菌。The biological conversion of soluble material into dense microbial biomass has essentially purified the wastewater and all that is subsequentl

22、y required is to separate the micro-organisms from the water by settlement. 可溶性物质生物转化为致密的微生物生物量基本上净化了废水，随后所需要的就是通过沉降将微生物从水中分离出来。Secondary sedimentation is essentially the same as primary sedimentation except that the sludge is comprised of biological cells rather than gross solids.二次沉淀本质上与初次沉淀相同，只是污

23、泥是由生物细胞而非固体颗粒组成。There are two main types of reactors, those where the micro-organisms are attached to a fixed surface (e.g. percolating filter) and those where the micro-organisms mix freely within the wastewater (e.g. activated sludge). 反应器主要有两种类型，一种是微生物附着在固定表面上的反应器(例如渗滤过滤器) ，另一种是微生物在废水中自由混合的反应器(例如

24、活性污泥法)。In the latter, the biological cells which are separated after secondary settlement are returned to the reactor to maintain a high microbial density in order to maintain maximum microbial breakdown of the wastewater. 在后者中，经过二次沉降分离的生物细胞回到反应器中，以保持较高的微生物密度，从而保持废水中微生物的最大分解。The secondary treatment

25、phase may comprise of other biological systems, either aerobic or anaerobic, or incorporate a mixture of several systems.二级处理阶段可以包括其他生物系统，好氧或厌氧系统，或者包括多个系统的混合物。Tertiary treatment三级处理Primary and secondary treatment will normally be able to produce a 20:30 effluent, often even better, but when the dilution available in the receiving water is inadequate and the water quality is already under stress, then further treatment of the secondary effluent will be necessary. 一级和二级处理通常可产生20:30的污