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1、给水排水工程与环境工程专业英语Part Four Wastewater TreatmentUnit 14 Activated Sludge ProcessesNew Words and Expressionsculture n . 培养（物）secrete v . 分泌capsule n . n . (pl. fungi) 真菌nematode n . 线虫rotifer n . 轮虫free-swimming a . 游动的，游泳型的nominal a . 标公称的，额定的decant n . v . 倾注倒，滗sorption n . 吸收附（作用）lump v . 归纳总结；使成块团up
2、take n . 提取，吸收stoichiometrically ad . 化学计算量equivalent n . 当量process configuration 工艺过程构型排列，组合continuous-flow stirred-tank reactor 连续流搅拌（池）反应器plug-flow 推流，活塞流BODu = BOD ultimate 最终生化需氧量wasting rate 排泥速率sludge age （污）泥龄TEXT Activated sludge process is a biological wastewater treatment process in which
3、 a mixture of wastewater and activated sludge is agitated and aerated. 活性污泥法是一种生物废水处理方法。处理过程中将废水和活性污泥的混合液搅拌并加以曝气。The activated sludge is subsequently separated from the treated wastewater by sedimentation and allowed to go to waste or returned to the process as needed. The treated wastewater overflo
4、ws the weir of settling tank (as shown in Fig.14.1). 接下来经过沉淀把活性污泥从处理过的废水中分离开，根据需要，活性污泥可以排掉或者回用。处理过的废水从沉淀池出水堰溢流出。（如图14-1所示）。 Activated sludge is that sludge which settles down after the wastewater has been freely aerated and agitated for a certain time. This activated sludge contains numerous bacteri
5、a and other microorganisms. 活性污泥就是废水经过一段时间自然曝气和搅拌之后沉淀下来的污泥。这种活性污泥含有许多细菌和其他微生物。When it is mixed with raw wastewater saturated with oxygen, the bacteria are used to oxidize the organic solids, promote coagulation and flocculation, and convert the colloidal and suspended solids into settleable solids.当
6、污泥与饱和氧的原生废水混合时，利用污泥中的细菌可氧化有机固体，提高混凝和絮凝效果，把胶体固体和悬浮固体转变为可沉降的固体。 Figure 14-1 Flow Sheet of Activated Sludge Processes推流式曝气池推流式曝气池澄清池澄清池回流污泥回流污泥完全混合曝气池完全混合曝气池 A suspended aerobic microbial culture is used to treat the incoming wastewater in activated sludge processes. 在活性污泥法中，利用悬浮好氧微生物培养物处理流入的污水。At the
7、end of the reaction period the microbial culture is separated from the liquid being treated. Most of the culture is returned and mixed with incoming wastewater. 当反应期结束时，从处理的废水中把微生物培养物分离出来。 大部分微生物培养物返回到流入的废水中，并与之混合。Under conditions existing in the activated sludge process, the microbial culture grows
8、 in clumps or flocs that contain large numbers of bacteria held together by the secreted polymers that accumulate on their capsules.在活性污泥工艺现有的条件下，微生物培养物呈团状或絮状体生长，这些团状或絮状体含有大量的细菌，这些细菌有聚集在它们荚膜上的分泌聚合物结合在一起。 Typical flocs are shown in the scanning electron micrograph. The bacterial cells are scattered t
9、hrough the floc interior and actually make up only about 10 to 25 percent of the floc volume, as can be seen in the transmission electron micrograph. (1) 典型的絮状体可用电子扫描显微照片显示。 正如在电子传输显微照片中见到的那样，细菌细胞在絮状体内部分散开，实际上它们仅占絮体体积的10-25左右。Maximum floc size is controlled by shear stress in the reactor, and minimu
10、m floc size is controlled by the gravity sedimentation process used to separate the culture from the treated effluent.反应器内的剪应力控制最大絮状体的尺寸；用于把细菌培养物与处理过的污水分开的重力沉淀法控制最小絮体的尺寸。 Organisms other than bacteria (fungi, protozoa, etc.) live in or on the flocs but do not ordinarily occur in large numbers. Some
11、free-swimming organisms such as nematode worms and rotifers are found in activated sludge also. 除了细菌（真菌、原生动物等）以外的生物生活在絮状体内部或表面，但是一般不大量出现。在活性污泥中也发现一些游动的有机物，如线虫和轮虫。Protozoa and rotifers feed on free-swimming bacteria and are therefore aids in producing an effluent having low turbidity.原生动物和轮虫以游动细菌为食，因
12、而有助于生产低浊度的出水。 Because the actual bacterial population is very difficult to measure, the concentration of suspended solids or volatile suspended solids in the aeration tank is used as an estimate of the cell concentration. 由于实际细菌种群很难测到，所以将曝气池中的悬浮固体或挥发性悬浮固体的浓度作为细胞含量的估量。The mixture of wastewater and su
13、spended culture is referred to as the mixed liquor, and the respective suspended solids concentrations as mixed-liquor suspended solids (MLSS) and mixed-liquor volatile suspended solids (MLVSS). 废水和悬浮培养物的混合体称为混合液，悬浮固体浓度分别称为混合液悬浮固体（MLSS）和混合液挥发性悬浮固体（MLVSS） Process configuration The three basic activat
14、ed sludge process configurations in use are nominal plug-flow (PF), continuous-flow stirred-tank (CFST), and batch. 工艺构型使用中的三种基本活性污泥工艺过程构型是标称推流池（PF）、连续流搅拌池（CFST）和间歇池。Nominal PF is the most common. Mixing within the reactor is usually provided by the aeration system. The original activated sludge con
15、figuration was a single-unit batch reactor.标称推流池是最常见的。反应器内的混合通常是由曝气系统提供的。最初活性污泥工艺构型是单池间歇反应器。 Hydraulic problems with the decant portion of the operating cycle resulted in the development of continuous-flow systems utilizing a separate tank for culture / liquid separation. 由于工作周期闲置阶段的水力问题导致开发出连续流系统，该
16、系统利用分离池将培养物或者液体分离出去。Until the 1950s, virtually all activated sludge processes were nominal PF with a separate sedimentation tank. Settled cells were recycled or wasted as necessary. 直到20世纪50年代，实际上所有活性污泥工艺都是带有一个单独沉淀池的标称推流池。沉降下来的细胞可再循环或者必要时排掉。In the past 30 years, CFST activated sludge systems have be
17、come quite common, although most new processes are still nominal PF. Batch processes have reappeared as methods of decanting improved.在过去的30年中，尽管大多数新处理工艺仍是标称推流池，但连续流搅拌池活性污泥系统已经十分普遍。间歇法作为改进了的出水方法已重新出现。 Method of aeration Oxygen is transferred into the liquid phase of activated-sludge reaction vessels
18、, or aeration tanks, by a number of means. The most common method is the introduction of compressed air through diffusers at the bottom of the aeration tank. 曝气方法可利用各种方法将氧输送到活性污泥反应器即曝气池的液体中。最常见的方法是通过曝气池底部的扩散器输入压缩空气。Mechanical turbines, either surface or submerged, are also in widespread use. Submerg
19、ed turbines are often coupled to compressed air systems to provide intensive contact between the compressed air bubbles and the liquid.位于水面或潜入水中的机械涡轮也被广泛使用。潜水涡轮经常与压缩空气系统结合使用，以便在压缩空气气泡和液体之间形成紧密接触。Surface turbines act as pumps, pulling the liquid upward and throwing it radially in small droplets that
20、make contact with the air. For additional details on aeration see references.表面涡轮起到泵的作用，它把液体向上吸，然后径向抛出，形成与空气接触的小水珠。有关曝气的更多详细内容参考资料。Process modeling The overall biological reaction in the activated sludge process is the same as that in the BOD process discussed in Chapter 2. 工艺模型活性污泥法中总的生物反应与以前所讨论的生化
21、需氧量法相同。 Organic material + O2 + Nutrients bacteria New cells + CO2 + H2O (14-1) 细菌有机物+O2+营养素 新细胞+CO2+H2O （14-1）The rate of disappearance of the organic material and oxygen and the rate of formation of new cells are of particular interest in process design. 在工艺设计中，有机物和氧的消耗速率与新细胞形成速率非常重要。In most cases
22、, it is assumed that the mixing induced by the aeration system eliminates liquid-phase mass transport limitations.大多数情况下，假设曝气系统产生的混合能消除液相传质极限。In the rate expressions in common use all of the steps from sorption through metabolism are lumped together.在常用的速率表达式中，从吸收直到代谢的所有步骤都被归纳在一起。 Rate of oxygen upt
23、ake The oxygen uptake rate is related stoichiometrically to the organic removal rate and the growth rate. 吸氧速率 在化学计算上，吸氧速率与有机物去除速率和生长速率有关。If the organic concentration is given as BODu, the oxygen required to carry out the conversion shown in Eq. (14-1) is the difference between the initial BODu valu
24、e and the oxygen equivalents of the cells produced.如果有机物浓度已最终生化需氧量（BODU）给出，实现方程（14-1）所示转化的需氧量等于初始BODU与所生成的细胞的氧当量之差。The approximate conversion factor between the volatile suspended solids concentration and its oxygen equivalents is 1.42g of oxygen per gram of volatile solids.挥发性悬浮固体浓度与其氧当量之间的近似转换系数为每
25、克挥发性固体需氧1.42g。 The value of 1.42 is obtained by considering the amount of oxygen required to oxidize cell tissue to carbon dioxide, ammonia, and water. 1.42这个值是从考虑把细胞组织氧化成二氧化碳、氨和水所需氧气量的角度得到的。The rate of oxygen uptake is shown as the sum of the organic removal and growth rates, but it is important to
26、 remember that the sign of the term ro* (rate of organic removal as BODu) is negative.吸氧速率可表示为有机物去除率与生长率之和，但重要的是记住r0（以BODU表示的有机物去除率），这项的符号是负的。 Sludge age Recycle of the MLSS in the activated sludge process allows separation of the average retention times of the wastewater and the microbial culture.
27、污泥龄 活性污泥法中，混合液悬浮固体的循环使得废水和微生物培养物的平均停留时间分开。The sludge age, often called the SRT (solids retention time) or MCRT (mean cell residence time), is defined as the average time the microbial culture stays in the system and is controlled primarily by the wasting rate.常常被称为固体停留时间（SRT）或细胞平均停留时间（MCRT）的污泥龄可定义为系
28、统内微生物培养物停留的平均时间，它主要受排泥速率控制。Wasting rates are usually set to give a sludge age between 3 and 10d. The sludge age is calculated from a mass balance on the entire system. 一般按泥龄3-10天确定排泥速率。根据整个系统的质量平衡可计算泥龄。 In making the mass balance when actual field data are not available, the average suspended-solids
29、 concentration in the sedimentation tank is assumed to be equal to the MLSS in the aeration tank. 在进行质量平衡过程中，当没有实际现场资料时，可认为沉淀池内悬浮固体平均浓度等于曝气池中混合液悬浮固体。Calculation of the sludge age and relationship between sludge age and cell growth are illustrated in Example 14.1 and 14.2, respectively.泥龄的计算和泥龄与细胞之间的
30、关系不可忽视。 Exercises1. Answer the following questions in English according to the text:(1) Why is the concentration of suspended solids or volatile suspended solids in the aeration tank used as an estimate of the cell concentration?(2) What is the sludge age?Notes(1) as can be seen in 此句是 as 引导的方式状语从句的
31、省略形式，这在科技英语中常见，译为“正如在 中所看到的那样。(2) and the respective suspended solids concentrations as 在 as 前面省略 “are referred to”.2. Use the following 5 words/expressions to make up 5 sentences, respectively: (1) fungus (2) compress (3) retention (4) uptake (5) volatile 3. Put the following English into Chinese:(
32、1) Diffused and mechanical aeration basins must supply sufficient air to maintain dissolved oxygen for the biota (生物群) to use in metabolizing the waste organicsRate of microbial activity is independent of dissolved oxygen concentration above a minimum critical value，below which the rate is reduced b
33、y the limitation of oxygen required for respiration. The exact minimum depends on the type of activated sludge process and the characteristics of the waste water being treatedThe most common design criterion for critical dissolved oxygen is 2.0 mg/1，but in actual operation values as low as 0.5 mg/1
34、lave proved satisfactory. Anaerobic systems must，of course，operate in the complete absence of dissolved oxygen；consequently，digesters are sealed with floating or fixed covers to exclude air. (2) Hydrogen ion concentration has a direct influence on biological treatment systems which operate best in a
35、 neutral environment. The general range of operation of aeration systems is between pH 65 and 8. 5Above this range microbial activity is inhibited，and below pH 6.5 fungi are favored over bacteria in the competition for metabolizing the waste organics Anaerobic digestion has a small pH tolerance rang
36、e of 6. 7 to 7. 4 with optimum operation at pH 7.0 to 7.1Limited success in digester pH control has been achieved by careful addition of lime with the raw sludge feed. Unfortunately，the buildup of acidity and reduction of pH may be a symptom of other digestion problems，for example，accumulation of toxic heavy metals which the addition of lime cannot cure.4. Put the following Chinese into English:(1) 微生物培养物的分离(2) 活性污泥法(3) 与空气接触的小水珠(4) 根据需要活性污泥可以排掉或者回用。(5) 在化学计算上，吸氧速率与有机物去除速率和生长速率有关
