The bold words in red are different with text book or uncertain.
Unit 10
Water Pollution and Pollutants
Solids The total solids (organic and inorganic) in wastewater are, by definition, residues after the liquid portion has been evaporated and the remainder dried to a constant weight at 103℃. 固体 废水中总固体(包括有机的和无机的)定义为:液体被蒸发后在103℃下烘干致恒重的剩余物.
Differentiation between dissolved solids and undissolved, that is, suspended, solids are accomplished by evaporating filtered and unfiltered wastewater samples.
通过蒸发滤过的和没有滤过的废水样来区分溶解性固体和悬浮的非溶解性固体.(这句话的英文好像有语法错误)
The difference in weight between the two dried samples indicates the suspended solids content. 而两个干燥样品的差值即是悬浮性固体含量.
To further categorize the residues, they are held at 550℃ for 15 minutes.
为进一步对这些残渣进行分类,可将它们置于550℃下15分钟.
The ash remaining is considered to represent inorganic solids and the loss of volatile matter to be a measure of the organic content.
剩余的灰分代表了无机固体,而挥发掉的那部分可用于衡量有机物含量.
Suspended solids (SS) volatile suspended solids (VSS) are the most useful. 悬浮固体和挥发性悬浮固体是最有用的.
SS and BOD (biochemical oxygen demand) are used as measures of wastewater strength and process performance.
SS和BOD(生化需氧量)被用作测定废水浓度和处理性能的手段.
VSS can be an indicator of the organic content of raw wastes and can also provide a measure of the active microbial population in biological processes.
VSS可作为未经处理的废物中有机物含量的指标,并可在生物过程中提供一个测量活性微生物种群数的方法.
Inorganic constituents The common inorganic constituents of wastewater include: 无机成分 废水中常规无机组分:
1. Chlorides and sulphates. Normally present in water and wastes from humans.
氯化物和硫酸盐.常见于人类产生的废水和废物中.
2. Nitrogen and phosphorous. In their various forms (organic and inorganic) in wastes from
humans, with additional phosphorous from detergents.
氮和磷.以多种形式(有机的和无机的)存在于人类产生的废物中,而磷还可来自于清洁剂. 3. Carbonates and bicarbonates. Normally present in water and wastes as calcium and
magnesium salts.
碳酸盐和碳酸氢盐.通常以钙盐和镁盐的形式存在于水和废物中.
4. Toxic substances. Arsenic, cyanide, and heavy metals such as Cd, Cr, Cu, Hg, Pd and Zn are
toxic inorganic which may be found in industrial wastes.
有毒物质.砷,氰化物和重金属如镉,铬,汞,铅和锌,这些可能存在于工业废物中物质,都是
有毒的无机物
In addition to these chemical constituents, the concentration of dissolved gases, especially oxygen, and hydrogen ion concentration expressed as pH are other parameters of interest in wastewater.
除了这些化学组分,溶解气体的浓度,特别是氧气的浓度,以及pH值所表示的氢离子浓度也是与废水有关的参数.
Organic matter Proteins and carbohydrates constitute 90 percent of the organic matter in domestic sewage.
生活污水中的有机物90%是由蛋白质和碳水化合物组成.
The sources of these biodegradable contaminants include excreta and urine from humans; food wastes from sinks; soil and dirt from bathing, washing and laundering; plus various soaps, detergents, and other cleaning products.
这些可生物降解的污染物的来源包括:人类的排泄物和尿;水槽的食物残渣;洗澡,洗涤和洗烫时产生的土和污垢;及各种肥皂,洗涤剂和其他一些清洁用品.
Various parameters are used as a measure of the organic strength of wastewater. 多种指标被用于测量废水中有机物的浓度.
One method is based on the amount of organic carbon (total organic carbon, or TOC) present in the waste.
其中一种方法是以废水中有机碳的含量(总有机碳,即TOC)为依据.
TOC is determined by measuring the amount of CO2 produced when the organic carbon in the sample is oxidized by a strong oxidizer and comparing it with the amount in a standard of known TOC.
TOC是通过将样品中有机碳被强氧化剂氧化后产生的CO2的量与已知TOC的标准进行比较而确定的.
Most of the other common methods are based on the amount of oxygen required to convert the oxidizable material to stable end products.
其他常用的方法多数是以可氧化物质转化成稳定的最终产物的需氧量为依据的.
Since the oxygen used is proportional to the oxidizable material present, it serves as a relative measure of wastewater strength.
由于氧的消耗与存在的可氧化物质成比例关系,故它可作为废水浓度的一种相对量度. The two methods used most frequently to determine the oxygen requirements of wastewater are the COD and BOD tests.
确定废水需氧量最常用的两种方法是COD和BOD的测定.
The COD, or chemical oxygen demand, of the wastewater is the measured amount of oxygen needed to chemically oxidize the organics present; the BOD, or biochemical oxygen demand, is the measured amount of oxygen required by acclimated microorganism to biologically degrade the organic matter in the wastewater.
废水的COD,即化学需氧量,是化学方法氧化现存有机物时所需的氧量;BOD,即生化需氧量,是驯化的微生物对废水中的有机物进行生物降解时所需的氧量.
BOD is the most important parameter in water pollution control.
BOD是水污染控制中最重要的参数.
It is used as measure of organic pollution, as a basic for estimating the oxygen needed for biological processes, and as an indicator of process performance.
它可用于有机污染的测定,可作为估算生物进程需氧量的基础,还可作为处理性能的指标.
The amount of organic matter in water or wastewater can be measured directly (as TOC, for example), but this does not tell us the organics are biodegradable or not.
水或废水中有机物的含量可以直接被测出(如TOC),但却无法知道这些有机物可否进行生物降解.
To measure the amount of biodegradable organics, we use an indirect method in which we measure the amount of oxygen used by a growing microbial population to convert (oxidize) organic matter to CO2 and H2O in a closed system.
故我们采用一种间接法来测定可生物降解的有机物的量, ,即测定一个封闭系统中,生长期的微生物种群将有机物转化为CO2和H2O的耗氧量.
The oxygen consumed, or biochemical oxygen demand (BOD), is proportional to the organic matter converted, and therefore BOD is a relative measure of the biologically degradable organic matter present in the system.
这个耗氧量,即生化需氧量(BOD),与转化的有机物成比例关系,因此BOD是存在于系统中的可生物降解的有机物的一个相对量度
Because biological oxidation continues indefinitely, the test for ultimate BOD has been arbitrarily limited to 20 days, when perhaps 95 percent or more of the oxygen requirement has been met. 因为生物氧化延续的时长不确定,而20天时消耗的氧量可能是总需氧量的95%或更多,故我们主观地把最终BOD的测定时间限定为20天.
Even this period, however, is too long to make measurement of BOD useful, so a five-day test, BOD5, carried out at 20℃, has become standard.
然而,这样的耗时还是太长,以致BOD的测定不能发挥作用,所以在20℃下为期5天的测定,即BOD5,已经成为了一个标准.
The rate of BOD reaction depends on the type of waste present and the temperature and is assumed to vary directly with the amount of organic matter (organic carbon) present.
BOD的反应速率取决于现存污染物的类型和温度,且被认为会随着存在的有机物的量(有机碳)而变化.
Unit12
Water Purification
Primary Treatment
初级处理
When the sewage reaches the treatment plant, it first passes through a series of screens that remove large objects such as rats or grapefruits,
当污水到达污水处理厂,首先会经过一系列的格栅以去除如老鼠和葡萄柚之类的大物体, and then through a grinding mechanism that reduces any remaining objects to a size small enough to be handled effectively during the remaining treatment period.
然后通过一个磨碾机,将所有剩余物的大小减小至能被后面的治理工序有效的处理.
The next stage is a series of 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.
下一步是一系列的沉淀池,首先是去除粗沙,例如那些雨水从路面带进来的沙子,之后是去除那些沉淀较慢的悬浮固体-包括大约需要一小时才能沉淀下来的有机营养物. Up to this point the entire process, which is called primary treatment, has been relatively inexpensive but has not accomplished much.
到目前为止的整个过程,被称为初级处理,相对的便宜但没有完成多少任务.
Secondary Treatment 二级处理
The next series of steps is designed to reduce greatly the dissolved or finely suspended organic matter by some form of accelerated biological action.
接下来的一系列步骤是通过促进生物作用,较大程度的减少溶解的或微小的悬浮有机物. What is needed for such decomposition is oxygen and organisms and an environment in which both have ready access to the nutrients.
分解作用需要氧和生物体以及一个使两者都易于接近营养物的环境. One device for accomplishing this objective is the trickling filter. 用于达到上述目的一个装置是滴滤池.
In this device, long pips rotate slowly over a bed of stones, distributing the polluted water in continuous sprays.
在这个装置中,长管在石床上缓慢的旋转,并持续的喷洒使污水散布.
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.
当水滴徐徐淌过那些石头表面和四周，在有空气的情况下，它会将养分提供给大量的相当令人倒胃口的生物.
An alternative technique is the activated sludge process. 另一种技术是活性污泥法.
Here the sewage, after primary treatment, is pumped into an aeration tank, where it is mixed for several hours with air and bacteria-laden sludge.
经过初级处理的污水被灌入一个曝气池,在那里与空气和含有细菌的污泥混合几个小时. The biological action is similar to that which occurs in the trickling filter.
这里的生物作用类似于滴滤池中发生的.
The sludge bacteria metabolize the organic nutrients; the protozoa, as secondary consumers, feed on the bacteria.
污泥中的细菌代谢有机养分;而作为次级消费者的原生动物又以这些细菌为食.
The treated waters then flow to a sedimentation tank, where the bacteria-laden solids settle out and are returned to the aerator.
处理后的水会流入一个沉淀池,含有细菌的固体在这里沉降并被送回到曝气池中. Some of the sludge must be removed to maintain steady-state conditions. 部分污泥必须被去除以维持一个稳定状态.
The activated sludge process requires less land space than the trickling filters, and, since it exposes less area to the atmosphere, it does not stink so much.
活性污泥法的占地面积比滴滤池的少,并且因为它更少的暴露在空气中,故不会散发太多的臭味.
The effluent from the biological action is still laden with bacteria and is not fit for discharge into open waters, let alone for drinking.
生物处理后的出水仍然含有细菌,所以并不适合排放到地表水中,更不必说饮用了. Since the microorganisms have done their work, they may now be killed. 既然微生物已经完成了它们的工作,现在可以把它们杀死了.
The final step is therefore a disinfection process, usually chlorination. 因此最后的步骤就是消毒,通常采用加氯消毒.
Chlorine gas, injected into the effluent 15 to 30 minutes before its final discharge, can kill more than 99 percent of the harmful bacteria.
在最后排放前,将氯气注入出水中15到30分钟,可以杀死超过99%的有害细菌.
Tertiary or “Advanced” Treatments 三级或高级处理
Although considerable purification is accomplished by the time wastewaters have passed though the primary and secondary stages, these treatments are still inadequate to deal with some complex aspects of water pollution.
尽管废水在通过初级和二级处理时,已经得到了相当大程度的净化,但是这些处理仍然不适于处理水污染某些复杂的方面.
First, many pollutants in sanitary sewage are not removed. 首先,许多生活污水中的污染物没有被清除.
Inorganic ions, such as nitrates and phosphates, remain in the treated waters; these materials, as we have seen, serve as plant nutrients and are therefore agents of eutrophication.
无机离子,如硝酸盐和磷酸盐,留在了被处理过的水中;正如我们所知道的, 这些物质成为了植物的营养,并成为富营养化的因素.
The treatment methods available to copy with these troublesome wastes are necessarily specific to the type of pollutant to be removed, and they are generally expensive.
能有效应付这些麻烦废物的处理方法必然是对要清除的污染的类型有针对性的,并且它们一般较昂贵.
A few of these techniques are described below. 下面描述了几种这些技术.
1. Coagulation and Sedimentation 混凝和沉淀
As mentioned earlier in the discussion of biological treatment, it is advantageous to change little particles into big ones that settle faster.
正如之前在生物处理的讨论中提到的那样,这有利于使小颗粒变成沉淀得更快的大颗粒.(小颗粒变成大颗粒有利于更快的沉淀)
So it is also with inorganic pollutants. 对无机污染物来说也是如此.
Various inorganic colloidal particles are water loving (hydrophilic) and therefore rather adhesive;