给排水专业英文文献翻译
给水排水专业英语翻译
《给水排水专业英语》Lesson 1specific yield [spə'sifik] [ji:ld] 单位产水量mass curve 累积曲线capital investment 投资recurring natural event ['nætʃərəl] 重现历史事件subterranean [sʌbtə'reiniən] 地下的groundwater 地下水surface water 地表水tap [tæp]开关、龙头；在…上开空（导出液体）swampland ['swɔmplænd] n. 沼泽地；沼泽地带capillary [kə'piləri] n. 毛细管adj. 毛状的,毛细管的hygro- [词头] 湿（气），液体hygroscopic [,haigrəu'skɔpik] adj. 易湿的，吸湿的hygroscopic moisture 吸湿水stratum ['streitəm] n. [地质学]地层，[生物学]（组织的）层aquifer ['ækwəfə] ['ækwifə] n.含水层，地下蓄水层saturation [,sætʃə'reiʃən] n.饱和(状态)，浸润，浸透，饱和度hydrostatic [,haidrəu'stætik] adj. 静水力学的, 流体静力学的hydrostatic pressure 静水压力water table 1. 地下水位，地下水面，潜水面2. 【建筑学】泻水台；承雨线脚；飞檐；马路边沟[亦作water-table]Phreatic surface [fri(:)'ætik]地下水（静止）水位，浅层地下水面Superficial [sju:pə'fiʃəl] adj. 表面的,表观的，浅薄的Porosity [pɔ:'rɔsiti] n. 多孔性,有孔性,孔隙率Unconfined ['ʌnkən'faind] adj. 无约束的，无限制的Permeability [,pə:miə'biliti] n. 弥漫, 渗透, 渗透性Permeameter [pə:mi'æmitə] n.渗透仪,渗透性试验仪)Clay [klei] n. 粘土，泥土gravel ['ɡrævəl]n.[总称]砾，沙砾，小石；砾石cone of depression [kəun] 下降漏斗, [水文学]下降锥体drawdown ['drɔ:daun] n. 水位下降(降落,消耗,减少)integrate ['intigreit] 【数学】作积分运算；求积分observation well [,əbzə:'veiʃən] 观测井，观测孔extraction [ik'strækʃən] n. 抽出，取出，提取（法），萃取（法）derivation [deri'veiʃən] n. 1. 导出，引(伸)出，来历，出处，得出，得到；诱导，推论，推理；溯源【数学】1) (定理的)求导，推导2) 微商，微分，导数【语言】词源，衍生deplete [di'pli:t] v. 耗尽, 使...衰竭refuse [ri'fju:z] n. 废物,垃圾vt. 拒绝，谢绝dump [dʌmp] n. 垃圾场，垃圾堆，堆存处vt. 倾卸，倾倒(垃圾)unconfined aquifer 潜水含水层，非承压含水层，无压含水层confined aquifer 自流含水层，承压含水层homogeneous [,hɔməu'dʒi:njəs] adj. 同类的,相似的，均匀的，均相的；同种类的，同性质的；相同特征的Aquaclude 不透水层，难渗透水的地层Offset ['ɔ:fset] n.偏移量抵销，弥补，分支，胶印，平版印刷，支管，乙字管Vt. 弥补,抵销,用平版印刷vi. 偏移，形成分支sophisticated [sə'fistikeitid] adj. 复杂的，需要专门技术的；诡辩的,久经世故的equilibrium [,i:kwi'libriəm] n. 平衡,均衡Water Supply（给水工程）A supply of water is critical to the survival of life, as we know it.（众所周知，水对生命的生存至关重要。
给排水工程屋顶排水中英文对照外文翻译文献
中英文对照外文翻译(文档含英文原文和中文翻译)Short and Long Term Advantage roof drainage design performance Decade has witnessed great changes in the design of the roof drainage system recently, particularly, siphon rainwater drainage system has been gradually improved, and there is likely to be the key application. At the same time these changes, urban drainage system design has undergone tremendous changes, because the scope of a wider urban drainage system design for sustainable development, as well as people for climate change flooding more attention. The main contents of this article is how to design roof drainage systems and make a good performance. Special attention is how to get rid of bad habits already formed the design, but also need to consider innovative roof drainage system, such as green roofs and rainwater harvesting systems.Practical application: In the past few years, the design of the roof rainwater drainage system has undergone tremendous changes. On large buildings, siphon rainwater drainage technology has been very common, as well as green roofs because it is conducive to green development, being more and more applications. Taking into account the ongoing research, this article focuses on how to effectively design a variety of roof rainwater drainage system, and make it achieve the desired design effect.1. IntroductionIn the past decade, the city and the water drainage system design has been widely accepted thinking about sustainable urban drainage system, or the optimal management direction. The main principles of the design of these systems is both a local level in line with the quality of development, but also to create some economic benefits for the investors. This principle has led to the development of new changes in the sump. Although the application of such a device isgradually reduced, but the urban environment relatively high demand areas still require 100% waterproof and rapid drainage, such as the roof. Typically roof drainage system in the design, construction and maintenance has not been given due attention. Although the drainage system investment costs account for only a small portion of the total construction investment, but not able to judge the loss caused by poor design.There are two different forms of roof drainage system design methods, namely the traditional and siphon method. Traditional systems rely on atmospheric pressure work, the drive ram affected sink flow depth. Therefore, the conventional roof drainage systems require a relatively large diameter vertical drop tube, prior to discharge, all devices must be connected to the groundwater collection pipe network. In contrast, siphonic roof drainage pipe systems are generally designed to full flow (turbulent flow means that require less exhaust pipe), which will form a negative pressure, the larger the higher flow rate and pressure head. Typically siphon system requires less down pipe work under negative pressure to the water distribution network can mean higher altitude work, thereby reducing the amount of underground pipe network.Both systems consists of three parts: the roof, rainwater collection pipes, pipe network.All of these elements are able to change the water pressure distribution system. This section focuses on the role and performance of each part. Due to the principle of siphon system has not been well understood, resulting argument is relatively small, this article will highlight siphon system.2. RoofThe roof is usually designed by the architect, designer and not by the drainage design. There are three main roof.2.1 Flat roofFlat roofs are used in industrial buildings less rainfall regions and countries. This roof is not completely flat, but lower than the minimum roof slope may require. For example, the United Kingdom require maximum slope of 10 °. Setting minimum slope in order to avoid any unnecessary water.Despite the flat roof if it is not properly maintained will have more problems, but it will reduce the dead zone within the building, and the ratio of sloping roofs in favor of indoor air.2.2 sloping roofsMost residential and commercial buildings are pitched roof, inclined roof is the biggest advantage can quickly drain, thereby reducing leakage. In temperate regions, we need to consider carrying roof snow load. Once it rains, rainfall through the sloping roofs can be determined by calculation. When rainfall data can be used, you can use the kinematic theory to solve such problems.2.3 green roof (flat or inclined)It can prove roof is the oldest green roofs, including rainfall can reduce or disperse roof planted with plants. It can be planted with trees and shrubs roof garden, it can also be a vegetated roof light carpet. Wherein the latter technique has been widely used. Some of these applications tend to focus on aesthetic requirements and are often used in green development. Since the aesthetic requirements and pressure requirements, as well as green roofs thermal insulation function, reduce the heat island effect, silencer effect, extend the life of the roof.Green roofs in Germany, the most widely used, followed in North America, but to consider the impact on the aesthetics. Germany is by far the most experienced countries in the 19th centuryhave practical application, then as an alternative to reduce the risk of fire tar roof an option in urban areas. Germany is currently the main research question on the cultivation of other issues to consider smaller cities. A study from 1987 to 1989, was found packed with 70 mm thick green roof can be reduced by 60% -80% of heat loss. In a Canadian work computer model based on the roof indicates that as long as the sump, the area can reach 70% of the roof area can be reduced by 60 percent in one year, the same model was also used for artificial rainfall, which the results indicate that rainfall in the catchment season helps to drain away rainwater.However, none of these studies show that green roofs can play a useful role in the rainfall season, or how high collection efficiency of water supply. The United States did some tests, as long as the green roofs regular watering, can reduce 65 percent of the runoff in a rainfall. America's most authoritative green roof guidelines by the New Jersey state environmental agencies promulgated. The main principle is to solve the structural problems of light, and how can the normal drainage after two years.Rainfall period is based on the probability of failure is determined. The system is typically based on rainfall during rainstorms two minutes, two minutes, have a choice. Although this model will get more traffic, but there is no other better alternative. Studies have shown that the traditional model is applied to study green roofs are premature.Loss factor than traditional roof records should be small, about 98.7%.Peak flow will be reduced, although not penetrate, the surface roughness but also have a significant impact.Concentrated rainfall than two minutes for a long time, especially for large roof areas, such as public buildings, commercial buildings, industrial buildings.Urban drainage design should also consider other factors, for a complex system, a green roof in a rain is not enough. Water flow duration curve shows a longer than traditional systems. And two independent and will affect between is possible, which requires a more precise time period. 3. Rainwater CollectorBasic requirements rainwater collector is designed to be able to accommodate rainfall rainstorms. Although it is possible to make a slightly inclined roof drainage purposes, but the nature of the construction industry and building settlement will become flat roof Typically, the tank is placed in a horizontal, sectional view of the water is outwardly inclined, which the role of hydrostatic.3.1 drain outletAnalyzing rainwater collector has sufficient volume is the key to the sump outlet external setting conditions. Also affect the flow rate into the storm water drainage system piping, but also affect the depth of the water catchment. Although the depth of the sump will not bring any particular problems, but too deep can cause excessive sump.Numerous studies in the 1980s showed that the flow of conventional roof drainage system outlet can be divided into two cases. It depends on the size of the depth and size of the outlet. When the water depth is less than half the diameter of the outlet, the flow of the first type, and the outlet of the flow can be calculated by an appropriate equation; water depth increases, exports are slowly clogging the flow will become another form forms, at the same time, the flow of exports can be obtained through other equations. While conventional roof drainage systems are designed to be free-draining, but may cause limitations encountered in the design of the flow is not free. In this case, it will require additional depth.Siphon roof drainage systems, the outlet is designed to be submerged stream. In this case, the depth of the outlet of the decision is more complicated, because the design of the sump depends on the flow. Recent studies have shown that conventional roof drainage systems use a variety of non-standard catchment, their depth and height, bigger than the diameter of the outlet. This will eventually result in a siphon effect. For a given catchment, the flow depends on the starting end of the drop tube diameter. A similar phenomenon has also been used to study the standard catchment, in these circumstances, only limited siphon action occurs within relatively close distance from the exit.3.2 tank flow classificationIn the complex flow sump outlet flow classification, can be seen from Table 2a, the flow will be uniform layering, regardless of whether the same inlet flow. Table 2b and 2c show, export distribution will greatly influence the flow.When the outlet is not a free jet, sump outlet complex flow classification is difficult to describe. Because each catchment tank pressures are likely to be merged. For example, the siphon tube system design point is at near full jet outlet flow classification depends on the energy loss of each branch.3.3 hydrostatic sectionalSump shape of the water surface in the canal can be classified according to the flow equation. In most cases, a low flow rate means that there is less friction loss, if exports are free jet, the friction loss is negligible cross-section through the hydrostatic equation 1 to determine the horizontal distance.Where Q-- flow (m3 / s)T- surface width (m)g- acceleration of gravity (m / s2)F- flow area (m2)Equation 1 can not be ignored when the friction required to correct (or very long pipe velocity is large), or not a free jet.3.4 The current design methodsThe previous discussion has highlighted the main factors that should be considered with sink design. However, without the help of a certain number of models, computing hydrostatic sectional roof drainage system, the volume of the sump is possible. This large commercial and manufacturing industry, is a development opportunity, you can merge several kilometers of water routes. Thus, the conventional drainage system sump design methods are mainly based on experience, and assume that exports are free jet.Sump location in the building, it may cause the example to fail.Different interface sumpExcept in the case cited above, but also allows designers to use empirical data.3.5 Digital ModelLarge number of digital models can be used to accurately describe the flow of any form of catchment tank, regardless of whether the roof flows stable. An example of this model is a combination of roof space model. This model enables users to classify different aspects of the data indicated, includes: details of the rains, the roof surface drainage and other details. Kinematics have also been used to study rainwater tank to flow from the research collection. A typical method is based on open system to solve a basic problem of spatial mobility. This model automaticallyresolve the sump outlet flow situation, but also to deal with the case of free jet can also be simulated space limited mobility and submerged discharge. Output values include depth and flow rate.Currently, the model is essentially just a variety of research tools, but also through practical engineering test. However, we should face up to the various role models.4 pipe systems groupComposition in the form and scope of the tube group determines the roof drainage system relies mainly on the traditional system or siphon action.4.1 Traditional stormwater systemsConventional roof drainage systems, the ground plane is generally vertical pipe-line network, connected to the sump outlet and underground drainage systems, critical systems as well as compensating tube. It should be emphasized that the angle between the ground and the compensating tube is less than 10 °. Capacity of the entire system relies mainly on the outlet tube instead of down.Flow vertical tube is usually free-flowing, full of only 33%, the efficiency depends on the excess length of the tube. If the drop tube long enough (typically greater than 5m), there may be an annular flow. Similarly, under normal circumstances flow compensation pipe is free-flowing, full of up to 70%. Such designed process both for the design, various equations can also be used.4.2 Siphon roof drainage systemIn contrast with the traditional drainage systems, Siphon roof drainage system relies on air flow outside the system, and the tube is full pipe flow stream.The designs are usually made on the assumption that the design of heavy rain, the system can quickly siphon discharge rainwater. This assumption allows the application of hydrostatic siphon system theory. Often used steady flow energy equation. While this approach ignores the small amount of energy loss at the entrance, but after the experiment showed that there are still conducive to practical use.However, steady-state design methods in the siphon system is exposed to rain when the system does not meet the standard requirements or changes in rainfall intensity is large is not applied. In the first case, there will be some mixing of air quality, annular flow occurs. These problems are not integrated in the system when more serious. Because usually designed rains are common, it is clear now design methodology over time may not apply to siphon system. This is a major disadvantage, because the design of the main problem is the noise and vibration problems.Despite the disadvantages of the prior design approach, but a lot of the world's very few engineering failure reports. When a failure occurs, most likely for the following reasons: An incorrect understanding of the operation pointsSubstandard materials listInstallation defectsMaintenance mismanagementTo overcome these disadvantages, we have recently launched a series of research projects, to discuss the siphon system, and the development of digital models. From this work we learn a lot. In contrast with conventional design methods of some assumptions, siphon system mainly has the following aspects:1) non-flow system of full flow2) levels of certain pipe-flowing full pipe flow3) full pipe flow downstream propagation through a vertical pipe, riser, etc.4) the inner tube flow occurs over the vertical section, the system to reduce the pressure5) downward tube is full pipe flow, there will be air lock6) appears completely siphon action until well into the air system is lower than a certain levelTable 4a column data indicate that below the design point, the system will siphon unstable flow, depth of the water collecting tank is insufficient to maintain the siphon action. Table 4b show that the unsteady flow in siphon system when it will appear.Table 5 lists the data output of a digital model. It can be seen that the model can accurately describe the siphon action, siphon and steady state, the data also show that the model can accurately describe the complex siphon action.5 ConclusionThis article has illustrated the critical roof drainage systems, but these are often overlooked in the urban drainage system design. This article also shows that the design process is a complex process, rely mainly on the performance of exports. The following conclusions are based on the design summed up:1) Run depend on three interacting parts: the roof, sump, water pipes2) Green roofs can reduce traffic and beautify the city3) the export performance of the system is essential4) siphon drainage system have a greater advantage in large-scale projects, but must be considered high maintenance costs5) Design siphon drainage system should consider additional capacity and operational issuesAlthough the green roof is a more attractive option, but the traditional roof of a building in the country will continue to dominate. Green roofs will be gradually developed, and gradually been widely accepted. Similarly, the roof drainage system shown effective that it will continue to play a huge role in the commercial building drainage systems.Roof drainage system of the greatest threats from climate change, existing systems tend to be not simply aging; rainfall patterns of change will result in inefficient operation, self-cleaning rate will be reduced. Changes in wind speed and the roof will also accelerate the aging of the roof, it is necessary to carry out maintenance. Taking into account the climate change, the increase in materials, roof collected rainwater will be more extensive. Currently, the amount of rain around the globe per person per day 7-300 liters in the UK, with an average consumption of 145L / h / d, of which only about one liter is used by people, about 30 per cent of the toilet, study shows If water shortage, rainwater collected on the roof of developed and developing countries are recommended approach.屋顶排水设计性能的近期与远期优势最近十年见证了屋顶排水系统设计方面的巨大变化，特别的是，虹吸雨水排水系统已经得到逐步改善，并且有可能得到重点应用。
给排水专业外文翻译
History of Water SupplyMan’s search for pure water began in prehistoric times. Much of his earliest activity is subject to speculation. Some individuals might have led water where they wanted it through trenches dug in the earth, a hollow log was perhaps used as the first water pipe.Thousands of years must have passed before our more recent ancestors learned to build cities and enjoy the convenience of water pipes to the home and drains for water-carried wastes. Our earliest archeological records of central water supply and wastewater disposal date back about 5000 years, to Nippur of Sumeria. In the ruins of Nippur there is an arched drain with the stones set in full "voussoir" position, each stone being a wedge tapering downward into place. Water was drawn from wells and cisterns.An extensive system of drainage conveyed the wastes from the palaces and residential districts of the city.The earliest recorded knowledge of water treatment is in the Sanskrit medical lore and Egyptian Wall inscri ptions. Sanskrit writings dating about 2000 B.C. tell how to purify foul water by boiling in copper vessels,exposing to sunlight, filtering through charcoal, and cooling in an earthen vessel.The earliest known apparatus for clarifying liquids was pictureed on Egyptian walls in the fifteenth and thirteenth centuries B.C. The first picture represents the siphoning of either water of settled wine. A second picture shows the use of wick siphons in an Egyptian kitchen.The first engineering report on water supply and treatment was made in A.D. 98 by Sextus Julius Frontinus, water-commissioner of Rome. He produced two books on the water supply of Rome. In these he described a settling reservoir at the head of one of the aqueducts. His writings were first translated into English by the noted hydraulic engineer Clemens Herschel in 1899.In the eight century A.D. an Arabian alchemist,Geber,wrote a rather specialized treatise on distillation that included various stills for water and other liquids.The English philosopher Sir Francis Bacon wrote of his experiments on the purification of water by filtration, boiling, distillation and clarification by coagulation. This was published in 1627, one year after his death. Bacon also noted that clarifying water trends to improve health and increase the "pleasure of the eye".The first known illutrated descri ption of sand filters was published in 1685 by LucAntonio Porzio, an Italian physician. He wrote a book on conserving the health of soldier in camps, based on his experience in the Austro-Turkish War. This was probably the earliest published work on mass sanitation.He described and illustrated the use of sand filters and sedimentation. Porzio also stated that his filtration was the same as "by those who built the wells in the Palace of the Doges in Venice and in the palace of Cardinal Sachett,at Rome."The oldest known archeological examples of water filtration are in Venice and the colonies she occupied. The ornate heads on the cisterns bear dates,but it is not known when the filters were placed.Venice,Built on a Series of islands, depended on catching and storing rainwater for its principal freshwater supply for over 1300 years. Cisterns were built and many were connected in stone-grated catch basins and then filtered through sand into cisterns.A comprehensive article on the water supply of Venice appeared in the Practical Mechanics Journal in 1863.The land area of Venice was 12.85 acres and the average yearly rainfall was 32 inches(in). Nearly all of this rainfall was collected in 177 public and 1900 private cisterns. Thesecisterns provided a daily average supply of about 4.2 gallons per capita per day(gpcd).This low consumption was due in part to the absence of sewers, the practice of washing clothes in the lagoon,and the universal drinking of wine. These cisterns continued to be the principal water supply of Venice until about the sixteenth century.Many experiments were conducted in the eighteenth and nineteenth centuries in England,France Germany,and Russia.Henry Darcy patented filters in france and England in 1865 and anticipated all aspects of the American rapid sand filter except coagulatin.He appears to be the first to apply the law of hydraulics to filter design.The first filter to supply water to a whole town was completed at Paisley,Scotland,in 1804,but this water was carted to consumers. In Glasgow, Scotland,in 1807 filtered water was piped to consumers.In the United States little attention was given to water treatment until after the Civil War. Turbidity was not as urgent a problem as in Europe. The first filters were of the slow sandtype,similar to British design. About 1890 rapid sand filters were developed in the United States and coagulants were introduced to increase their efficency. These filters soon evolved to our present rapid sand filters with slight modification.历史上的水供应人类对纯净水的搜寻开始于史前时代。
给水排水中英文对照外文翻译文献
中英文对照外文翻译文献(文档含英文原文和中文翻译)原文：Optimum combination of water drainage,water supply and eco-environment protection in coal-accumulated basin of North ChinaAbstract The conflict among water drainage,water supply and eco-environment protection is getting more and more serious due to the irrational drainage and exploitation of ground water resources in coal-accumulated basins of North China.Efficient solutions to the conflict are tomaintain long-term dynamic balance between input and output of theground water basins,and to try to improve resourcification of the mine water.All solutions must guarantee the eco-environment quality.This paper presents a new idea of optimum combination of water drainage，water supply and eco-environment protection so as to solve theproblem of unstable mine water supply,which is caused by the changeable water drainage for the whole combination system.Both the management of hydraulic techniques and constraints in economy,society,ecology,environment,insustuial structural adjustments and sustainable developments have been taken into account.Since the traditional and separate management of different departments of water drainage,water supply and eco-environment protection is broken up these departments work together to avoid repeated geological survey and specific evaluation calculations so that large amount of national investment can be saved and precise calculation for the whole system can be obtained.In the light of the conflict of water drainage,water supply and eco-environment protection in a typical sector in Jiaozuo coal mine,a case study puts forward an optimum combination scheme,in which a maximum economic benefit objective is constrained by multiple factors.The scheme provides a very important scientific base for finding a sustainable development strategy.Keywords combination system of water drainage,water supply and eco-environment protection,optimal combination,resourcification of mine water.1Analyses of necessity for the combinationThere are three related problems in the basin.It is well known that the major mine-hydrogeological characteristics of the coal accumulated basin in North China display a stereo water-filling structure,which is formed by multi-layer aquifers connected hydraulically together with various kinds of inner or outer boundaries.Mine water hazards have seriously restricted the healthy development of coal industry in China because of more water-filling sources and stronger water-filling capacity in coal mines of the basin.Coal reserves in the basin are threatened by the water hazards.In Fengfeng,Xingtai,Jiaozuo,Zibao,Huaibei and Huainan coal mine districts,for example,it is estimatedthat coal reserves are threatened by the water hazards up to 52％,71.％40,％,60％,48％and 90％of total prospecting reserves respectively.It is obvious that un-mining phenomenon caused by the water hazards is serious.Water-bursting accidents under coal layers have seriously influenced safe production.Some statistical data show that there were 17 water-bursting accidents with over 1 m3/s inflow from 1985.Water drainage is an increasing burden on coal mines threatened by water hazards:high cost of water drainage raises coal prices and reduces profits of the enterprise.On the other hand,it is more and more difficult to meet the demand of water supply in coal mine districts in the basin.The reasons are not only arid and semi-arid weather conditions,but also a large amount of water drainage with deep drawdown in coal mines and irrational water exploitation.The deterioration of eco-environment is another problem.Phenomena of land surface karst collapse can be found.Many famous karst springs,which are discharge points for the whole karst groundwater syatem,stop flowing or their discharge rates decrease on a large scale.Desert cremophytes in large areas in west China die because of falling groundwater level.These three problems are related and contradictory.In order to solve the problems while ensuring safe mining,meeting water resource demands and slowing down the pace of eco-environment deterioration,it is necessary to study the optimum combination of water drainage,water supply and eco-environment protection in the basin.2The state of the art of research and the problemsAlthough research into the combination of water drainage and water supply started much earlier in some countries,their conception is simple and some shortcomings remain in their study on the theory and pattern of combination.China’s research history on the combination can be divided into three stages.The first stage is the utilization of mine water.A century ago mine water started to be used as water supply for mines.But the utilization scale and efficiency were quite limited at that time.The second stage is a comprehensive one:mine water was used while water hazards were harnessed.Great progress was made both in theory and practice of the combination.For example,the combination of water drainage and water supply not only means the utilization of mine water,but also means that it is a technique of preventing water hazards.It is unfortunate,however,that the combination research in this stage offered less sense ofeco-environment protection.Optimum combination management of water drainage,water supply and eco-environment protection is the third stage.Main features in this stage are to widen traditional research,and to establish an economic-hydraulic management model,in which safe mining,eco-environment protection and sustainable development demands,etc.are simultaneously considered as constraint conditions.3Trinity systemThe trinity system combines water drainage,water supply and eco-environment quality protection.The water-collecting structures of the system consist of land surface pumping wells in the mines,shallow land surface well in groundwater recharge areas and artificial relief wells under the mines.Both integration and coordination for the trinity system are distinguished according to the combination.The integration for the system means to utilize drainage water under the mines and pump water onto the land surface as water supply for different purposes without harming the eco-environmental quality.The coal mines are not only drainage sites,but also water supply sources.The purpose of drilling pumping wells on the land surface is to eliminate special influences on different consumers,which are caused by terminating drainage processes under the mines due to unexpected accidents in mining.The coordination for the system means to bulid some water supply sources for different consumers while ensuring eco-environmental quality in groundwater recharge positions,where pumping groundwater is quite effective on lowering groundwater heads in the mine areas.Itintercepts in advance the recharging groundwater flow towards the mines,which may not only provide consumers with good quality groundwater,achieve the goal of dropping down groundwater heads in the mines,but also effectively reduce the high costs of drainage and water treatment,which are needed by traditional dewatering measures with large drainage flow rates under the mines.The coordination changes the traditional passive pattern of preventing and controlling groundwater hazards under the mines into that of active surface interception.Both very developed karst flow belts and accumulated groundwater recharge ones under the ground are relatively ideal interceptive coordination positions in the system.For the integration of the trinity system,artificial relief wells under the mines and the land surface pumping wells mainly penetrate into direct thin bedded karst aquifers interbedded with the mining coal layers,while for the coordination of the system,the shallow land surface wells mainly penetrate into very thick karst aquifer.Therefore,hydrogeological conceptual model for the system involves the multi-layer aquifers connected hydraulically by different inner boundaries.Setting up stereo hydrogeological conceptual models and corresponding mathematical models is a prerequisite for solving the managemental problems for the system.Management of the trinity system not only considers the effects of lowering groundwater heads and safe operation for water drainage subsystem,but also pays attention to the water demands for water supply subsystem and quality changes for eco-environment protection subsystem.They play the same important role in the whole combination system.It controls the groundwater heads in each aquifer to satisfy the conditions of safe mining with certain water head pressures in the mines,and to guarantee a certain amount of water supply for the mines and near areas,but the maximum drawdown of groundwater must not be ex ceded,which may result in lowering eco-environmental quality.4Economic-hydraulic management modelIn the trinity system management,groundwater resources in the mines and nearby areas,which are assessed on the premise of eco-environment qualities and safe operation in the mines,may be provided as water supply prices,drainage costs,transportation costs(including pipeline and purchasing the land costs)and groundwater quality treatment costs for the three different waterconsumers,the optimum management models may automatically allocate to each consumer a certain amount of groundwater resources and a concrete water supply scenario based on comparisons of each consumer’s economic contribution to the whole system in objective function.Therefore the management studies on the optimal combination among water drainage,water supply and eco-environment protection involve both the management of groundwater hydraulic techniques and the economic evaluations,eco-environment quality protection and industrial structure programs.In addition to realizing an economic operation,they also guarantee a safe operation which is a key point for the combination of the whole system.5The management model for the trinity system can reach water supply goals with drainage water under the mines and the land surface pumping water on the premise of ensuring eco-environmental quality.And it can make use of one model to lay down comprehensively optimum management scenarios for each subsystem by means of selecting proper constraints and maximum economic benefit objective produced by multiple water consumers.The model can raise the security and reliability of operation for the whole trinity system,and the drainage water can be forecast for the mines and the management of water supply resource and the evaluation of eco-environment quality can be performed at the same time so as to respectively stop the separate or closed management,of departments of drainage water,water supply and eco-environment protection from geological survey stage to management evaluation.This,in economic aspect,can not only avoid much geological survery and special assessment work which are often repeated by the three departments,and save a lot of funds,but also ,in technical aspect,make use of one model to simultaneously consider interference and influence on each other for different groundwater seepage fields so as to guarantee calculating precision of the forecast,the management and the evaluation work.The economic-hydraulic management model can be expressed as follows.6 A case studyA typical sector is chosen.It is located in the east of Jiaozuo coal mine,Henan Province,China.Itconsists of three mines:Hanwang Mine,Yanmazhuang Mine and Jiulishan Mine.The land surface is flat,and the whole area is about 30 km2.An intermittent river Shanmen flows through the sector from the north to the south.Average annual precipitation in the sector is about 662.3mm.Theprecipitation mainly concentrates inJune,July,August and September each year.Strata in the sector consist of very thick limestone in Middle Ordovician,coal-bearing rock series in Permo Carboniferous and loose deposits in Quaternary.There are four groups of faulted structures.The first is in northeast-southwest direction such as F3 and F1..The second is in the northwest-southeast direction such as Fangzhuang fault.The third is in the east-west direction such as Fenghuangling fault.The last is almost in north-south.These faults are all found to be normal faults with a high degree of dip angle.Four major aquifers have been found in the sector.The top one is a semi-confined porous aquifer.The next one is a very thin bedded limeston aquifer.The third is a thin bedded limestone aquifer.The last one at the bottom is a very thick limestone aquifer.Objective function of the management model is designed to be maximum economic benefit produced by domestic,industrial and agricultural water supply.Policy making variables of the model are considered as the domestic,industrial and agricultural groundwater supply rates in every management time step,and they are supplied by artificial relief flow wells under the mines,the land surface pumping wells in the mines and the shallow land surface wells in the groundwater recharge areas.All the 135 policy making variables are chosen in the model,27 for drainage wells under the mines in aquifer,27 for the land surface pumping wells in the mine districts in aquifer 27 in aquifer 27 in aquifer O2 27 for the shallow land surface wells in aquifer O2Based on the problems,the following constraint conditions should be considered:(1)Safe mining constraint with groundwater pressure in aquifer L8.There are altogether three coalmines in the typical sector,i.e.Hanwang Mine,Yanmazhuang Mine and Jiulishan Mine.Elevations of mining level for these mines are different because it is about 88-150 m in the second mining level for Hanwang Mine,and -200m in the second mining level for Yanmazhuang Mine,and-225 m in the first mining level for Jiulishan Mine.According to mining experiences,pressure-loaded heights for groundwater heads in safe mining state are considered as about 100-130m.Therefore,the groundwater level drawdowns in the three management time steps for aquifer L8 at three mines have to be equivalent to safe drawdown values at least in order to pervert groundwater hazards under the mines and to guarantee their safe operation.(2)Geological eco-environment quality constraint.In order to prevernt groundwater leakage fromupper contaminater porous aquifer into bottom one and then to seepage further down to contaminate the thin bedded limestone aquifer in the position of buried outcrop,the groundwater heads in the bottom porous aquifer must keep a certain height,i.e.the groundwater drawdowns in it are not allowed to exceed maximum values.(3)Groundwater head constraint at the shallow land surface wells in aquifer O2,The shallow landsurface wells should penetrate in aquifer O2 in order to avoid geological environment hazards,such as karst collapse and deep karst groundwater contamination.Groundwater head drawdowns in aquifer O2 for the shallow land surface wells are not allowed to exceed criticalvalues.(4)Industrial water supply constraint for the groundwater source in aquifer O2 .The rate ofindustrial water supply needed by the planned thermal power plant in the north of the sectoris designed to be 1.5 m3/s according to the comprehensive design of the system in thesector.In order to meet the demands of water,the rate industrial water supply for thegroundwater source in aquifer O2 in every management time step must be equivalent at leastto 1.5 m3/s.(5)Maximum amount constraint of groundwater resource available for abstraction.In order tomaintain the balance of the groundwater system in the sector for a long time and to avoid anyharmful results caused by continuous falling of groundwater head,the sum of groundwaterabstraction in each management time step is not allowed to exceed the maximum amount ofgroundwater resource available for abstraction.Since there is not only water drainage in the mines,but also water supply in the whole combination system,management period for the model is selected from June 1,1978 to May 31,1979,in which annual average rate of precipitation is about 50％.Management time steps for the period are divided into three.The first one is from June to September,the second from October to next January,and the last one from next February to May.According to comprehensive information about actual economic ability,economic development program and industrial structure adjustment in the sector at present and in the near future,and different association forms of water collecting structures among the land surface pumping wells,the shallow land surface wells and artificial relief flow wells under the mines,this paper designs 12 management scenarious,all of which take the safe operation in the trinity system as the most important condition.After making comparisons of optimum calculation results for the 12 scenarious,this paper comes to a conclusion that scenarios is the most ideal and applicable one for the typical sector.This scenario not only considers the effective dewatering advantage of the artificial relief flow wells under the mines and safe stable water supply advantage of the land surface pumping wells,but also pays attention to the disadvantage of low safe guaranty rate for the relief flow wells under the mines for water supply and of large drilling investment in the land surface pumping wells.Meanwhile,eh shallow land surface wells inaquifer O2in this scenario would not only provide water supply for the thermal power plant as planned,but also play an important role in dewatering the bottom aquifer,which is major recharge source of groundwater for the mines.If the drainage subsystem under the mines runs normally,this scenario could fully offer the effective dewatering functions of the artificial relief flow wells under the mines,and makes the trinity system operate normally.But if the drainage subsystem has to stop suddenly because of unexpected accidents,the scenario could still fully utilize the land surface pumping wells and the shallow land surface wells,and increae their pumping rates in order to make up for temporary shortage of water supply for the trinity system and to make its economic losses reduced to a minimum extent.Increasing groundwater abstraction rate for the land surface pumping wells and the shallow land surface wells,in fact,is very favorable for harnessing the water-accidents under the mines and for recovery production of the mines.To sum up,this scenario sets up a new pattern for the combination of water drainage,water supply and eco-environment protection.It solves quite well the conflicts between the low safe guaranty rate and the effective dewatering result for the artificial relief flow wells under the mines.It makes full use of beneficial aspect of the conflicts,and meanwhile compensates for the unbeneficial one by arranging the land surface pumping wells in the coal mine districts.Therefore,this scenario should be comprehensive and feasible.In this scenario,Hanwan Mine,Yanmazhuang Mine and Jiulishan Mine are distributed optimally for certain amount of domestic and industrial water supply,but not for much agricultural water supply.The land surface pumping wells are also distributed for different purposes of water supply.The water supply for the thermal power plant (1.5 m3/s) is provided by the shallow land surface prehensive effects,produced by the above three kinds of water collecting structures,completely satisfy all of the constraint conditions in the management model,and achieve an extremely good economic objective of 16.520551million RMB yuan per year.In order to examine the uncertainty of the management model,12management scenarios are all tested with sensitive analysis.7Conclusion(1)The optimum combination research among water drainage,water supply and eco-environmentprotection is of great theoretical significance and application value in the basin of North China for solving unbalanced relation between water supply and demands,developing new potential water supply sources and protecting weak eco-environment.(2)The combination research is concerned not only with hydraulic technique management but alsowith constraints of economic benefits,society,ecology,environment quality,safe mining and sustainable development in the coal mines.(3)The combination model,for the first time,breaks up the closed situation existing for a longtime,under which the government departments of drainage water,water supply and eco-environment protection from geological survey stage to management evaluation work respectively.Economically,it can spare the repeated geological survey and special assessment work done by the three departments and save a lot of funds;technically,one model is made use of to cover the interference and influence each other for different groundwater seepage fields soas to guarantee a high calculating precision of the forecast,the management and the evaluation work.(4)The management scenario presented in the case study is the most ideal and applicable for thetypical sector.This scenario not only makes full use of the effective dewatering advantages of the artificial relief flow wells under the mines and safe stable water supply advantages of the land surface pumping wells,but also pays attention to the disadvantages of low safe guaranty rate for the relief flow wells under the mines for water supply and of large drilling investment for the land surface pumping wells.References1.Investigation team on mine-hydrogeology and engineering geology in the Ministry ofGeology and Mineral Resources.Investigation Report on Karst-water-filling Mines(inChinese).Beijing:Geological Publishing House,19962.Liu Qiren,Lin Pengqi,Y u Pei,Investigation comments on mine-hydrogeological conditionsfor national karst-water-filling mines,Journal of Hydrogeology and Engineering Geology(in Chinese),19793.Wang Mengyu,Technology development on preventing and curing mine water in coalmines in foreign countries,Science and Technology in Coal(in Chinese),19834.Coldewey,W.G.Semrau.L.Mine water in the Ruhr Area(Federal Republic of Germany),inProceedings of 5th International Mine Water Congress,Leicestershire:Quorn SelectiveRepro Limited,19945.Sivakumar,M.Morten,S,Singh,RN,Case history analysis of mine water pollution,inProceedings of 5th International Mine Water Congress,Leicestershire;Quorn SelectiveRepro Limited,19946.Ye Guijun.Zhang Dao,Features of Karst-water-filling mines and combination betweenwater drainage and water supply in China,Journal of Hydrogeology and EngineeringGeology(in China),19887.Tan Jiwen,Shao Aijun,Prospect analyses on Combination between water drainage andwater supply in karst water basin in northern China,Jounnal of Hebei College ofGeology(in Chinese),19858.Xin Kuide,Yu Pei,Combination between water drainage and water for seriouskarst-water-filling mines in northern China,Journal of Hydrogeology and Engineering Geology(in Chinese),19869.Wu Qiang,Luo Yuanhua,Sun Weijiang et al.Resourcification of mine water andenvironment protection,Geological Comments(in Chinese),199710.Gao Honglian,Lin Zhengping,Regional characteristics of mine-hydrogeological conditionsof coal deposits in China,Journal of Hydrogeology and Engineering Geology(in Chinese),198511.Jiang Ben,A tentative plan for preventing and curing measures on mine water in coal minesin northern China,Geology and Prospecting for Coaofield(in Chinese),1993中国北方煤炭积聚区的最佳组合排水，供水和生态环境保护摘要为了开采中国北方煤炭资源丰富的区域，不合理的排水使排水、供水和保护生态环境之间的冲突日趋严重。
History of Water Supply专业给排水外文翻译
History of Water SupplyMan’s search for pure water began in prehistoric times. Much of his earliest activity is subject to speculation. Some individuals might have led water where they wanted it through trenches dug in the earth, a hollow log was perhaps used as the first water pipe. Thousands of years must have passed before our more recent ancestors learned to build cities and enjoy the convenience of water pipes to the home and drains for water-carried wastes. Our earliest archeological records of central water supply and wastewater disposal date back about 5000 years, to Nippur of Sumeria. In the ruins of Nippur there is an arched drain with the stones set in full "voussoir" position, each stone being a wedge tapering downward into place. Water was drawn from wells and cisterns.An extensive system of drainage conveyed the wastes from the palaces and residential districts of the city.The earliest recorded knowledge of water treatment is in the Sanskrit medical lore and Egyptian Wall inscri ptions. Sanskrit writings dating about 2000 B.C. tell how to purify foul water by boiling in copper vessels,exposing to sunlight, filtering through charcoal, and cooling in an earthen vessel.The earliest known apparatus for clarifying liquids was pictureed on Egyptian walls in the fifteenth and thirteenth centuries B.C. The first picture represents the siphoning of either water of settled wine. A second picture shows the use of wick siphons in an Egyptian kitchen.The first engineering report on water supply and treatment was made in A.D. 98 by Sextus Julius Frontinus, water-commissioner of Rome. He produced two books on the water supply of Rome. In these he described a settling reservoir at the head of one of the aqueducts. His writings were first translated into English by the noted hydraulic engineer Clemens Herschel in 1899.In the eight century A.D. an Arabian alchemist,Geber,wrote a rather specialized treatise on distillation that included various stills for water and other liquids.The English philosopher Sir Francis Bacon wrote of his experiments on the purification of water by filtration, boiling, distillation and clarification by coagulation. This was published in 1627, one year after his death. Bacon also noted that clarifying water trends to improve health and increase the "pleasure of the eye".The first known illutrated descri ption of sand filters was published in 1685 by Luc Antonio Porzio, an Italian physician. He wrote a book on conserving the health of soldier in camps, based on his experience in the Austro-Turkish War. This was probably the earliest published work on mass sanitation.He described and illustrated the use of sand filters and sedimentation. Porzio also stated that his filtration was the same as "by those who built the wells in the Palace of the Doges in Venice and in the palace of Cardinal Sachett,at Rome."The oldest known archeological examples of water filtration are in Venice and the colonies she occupied. The ornate heads on the cisterns bear dates,but it is not known when the filters were placed.Venice,Built on a Series of islands, depended on catching and storing rainwater for its principal freshwater supply for over 1300 years. Cisterns were built andmany were connected in stone-grated catch basins and then filtered through sand into cisterns.A comprehensive article on the water supply of Venice appeared in the Practical Mechanics Journal in 1863.The land area of Venice was 12.85 acres and the average yearly rainfall was 32 inches(in). Nearly all of this rainfall was collected in 177 public and 1900 private cisterns. These cisterns provided a daily average supply of about 4.2 gallons per capita per day(gpcd).This low consumption was due in part to the absence of sewers, the practice of washing clothes in the lagoon,and the universal drinking of wine. These cisterns continued to be the principal water supply of Venice until about the sixteenth century.Many experiments were conducted in the eighteenth and nineteenth centuries in England,France Germany,and Russia.Henry Darcy patented filters in france and England in 1865 and anticipated all aspects of the American rapid sand filter except coagulatin.He appears to be the first to apply the law of hydraulics to filter design.The first filter to supply water to a whole town was completed at Paisley,Scotland,in 1804,but this water was carted to consumers. In Glasgow, Scotland,in 1807 filtered water was piped to consumers.In the United States little attention was given to water treatment until after the Civil War. Turbidity was not as urgent a problem as in Europe. The first filters were of the slow sand type,similar to British design. About 1890 rapid sand filters were developed in the United States and coagulants were introduced to increase their efficency. These filters soon evolved to our present rapid sand filters with slight modification.历史上的水供应人类对纯净水的搜寻开始于史前时代。
建筑工程及给排水专业中英文对照翻译
建筑工程及给排水专业中英文对照翻译Laminar and Turbulent FlowObservation shows that two entirely different types of fluid flow exist. This was demon- strated by Osborne Reynolds in 1883 through an experiment in which water was discharged from a tank through a glass tube. The rate of flow could be controlled by a valve at the outlet, and a fine filament of dye injected at the entrance to the tube. At low velocities, it was found that the dye filament remained intact throughout the length of the tube, showing that the particles of water moved in parallel lines. This type of flow is known as laminar, viscous or streamline, the particles of fluid moving in an orderly manner and retaining the same relative positions in successive cross- sections.As the velocity in the tube was increased by opening the outlet valve, a point was eventually reached at which the dye filament at first began to oscillate and then broke up so that the colour was diffused over the whole cross-section, showing that the particles of fluid no longer moved in an orderly manner but occupied different relative position in successive cross-sections. This type of flow is known as turbulent and is characterized by continuous small fluctuations in the magnitude and direction of the velocity of the fluid particles, which are accompanied by corresponding small fluctuations of pressure.When the motion of a fluid particle in a stream is disturbed, its inertiawill tend to carry it on in the new direction, but the viscous forces due to the surrounding fluid will tend to make it conform to the motion of the rest of the stream. In viscous flow, the viscous shear stresses are sufficient to eliminate the effects of anydeviation, but in turbulent flow they are inadequate. The criterion which determines whether flow will be viscous of turbulent is therefore the ratio of the inertial force to the viscous force acting on the particle. The ratioμρvl const force Viscous force Inertial ?= Thus, the criter ion which determines whether flow is viscous or turbulent is the quantity ρvl /μ, known as the Reynolds number. It is a ratio of forces and, therefore, a pure number and may also be written as ul /v where is the kinematic viscosity (v=μ/ρ).Experiments carried out with a number of different fluids in straight pipes of different diameters have established that if the Reynolds number is calculated by making 1 equal to the pipe diameter and using the mean velocity v , then, below a critical value of ρvd /μ = 2000, flow will normally be laminar (viscous), any tendency to turbulence being damped out by viscous friction. This value of the Reynolds number applies only to flow in pipes, but critical values of the Reynolds number can be established for other types of flow, choosing a suitable characteristic length such as the chord of an aerofoil in place of the pipe diameter. For a given fluid flowing in a pipe of a given diameter, there will be a critical velocity of flow corresponding to the critical value of the Reynolds number, below which flow will be viscous.In pipes, at values of the Reynolds number > 2000, flow will not necessarily be turbulent. Laminar flow has been maintained up to Re = 50,000, but conditions are unstable and any disturbance will cause reversion to normal turbulent flow. In straight pipes of constant diameter, flow can be assumed to be turbulent if the Reynolds number exceeds 4000.Pipe NetworksAn extension of compound pipes in parallel is a case frequently encountered in municipal distribution system, in which the pipes are interconnected so that the flow to a given outlet may come by several different paths. Indeed, it is frequently impossible to tell by inspection which way the flow travels. Nevertheless, the flow in any networks, however complicated, must satisfy the basic relations of continuity and energy as follows:1. The flow into any junction must equal the flow out of it.2. The flow in each pipe must satisfy the pipe-friction laws for flow in a single pipe.3. The algebraic sum of the head losses around any closed circuit must be zero.Pipe networks are generally too complicated to solve analytically, as was possible in the simpler cases of parallel pipes.A practical procedure is the method of successive approximations, introduced by Cross. It consists of the following elements, in order:1. By careful inspection assume the most reasonable distribution of flows that satisfies condition 1.2. Write condition 2 for each pipe in the formh L = KQ n(7.5) where K is a constant for each pipe. For example, the standard pipe-friction equation would yield K= 1/C2and n= 2 for constant f. Minor losses within any circuit may be included, but minor losses at the junction points are neglected.3. To investigate condition 3, compute the algebraic sum of the head losses around each elementary circuit. ∑h L= ∑KQ n. Consider losses from clockwise flows as positive, counterclockwise negative. Only by good luck will these add tozero on the first trial.4. Adjust the flow in each circuit by a correction, ΔQ , to balance the head in that circuit and give ∑KQ n = 0. The heart of this method lies in the determination of ΔQ . For any pipe we may writeQ = Q 0 ＋ΔQwhere Q is the correct discharge and Q 0 is the assumed discharge. Then, for a circuit100/Q h n h Q Kn Q K Q L L n n ∑∑∑∑?-=-=- (7.6) It must be emphasized again that the numerator of Eq. (7.6) is to be summed algebraically, with due account of sign, while the denominator is summed arithmetically. The negative sign in Eq.(7.6) indicates that when there is an excess of head loss around a loop in the clockwise direction, the ΔQ must be subtracted from clockwise Q 0’s and added to counterclockwise ones. The reverse is true if there is a deficiency of head loss around a loop in the clockwise direction.5. After each circuit is given a first correction, the losses will still not balance because of the interaction of one circuit upon another (pipes which are common to two circuits receive two independent corrections, one for each circuit). The procedure is repeated, arriving at a second correction, and so on, until the corrections become negligible.Either form of Eq. (7.6) may be used to find ΔQ . As values of K appear in both numerator and denominator of the first form, values proportional to the actual K may be used to find the distribution. Thesecond form will be found most convenient for use with pipe-friction diagrams for water pipes.An attractive feature of the approximation method is thaterrors in computation have the same effect as errors in judgment and will eventually be corrected by the process.The pipe-networks problem lends itself well to solution by use of a digital computer. Programming takes time and care, but once set up, there is great flexibility and many man-hours of labor can be saved.The Future of Plastic Pipe at Higher PressuresParticipants in an AGA meeting panel on plastic pipe discussed the possibility of using polyethylene gas pipe at higher pressures. Topics included the design equation, including work being done by ISO on an updated version, and the evaluation of rapid crack propagation in a PE pipe resin. This is of critical importance because as pipe is used at higher pressure and in larger diameters, the possibility of RCP increases.Se veral years ago, AGA’s Plastic Pipe Design Equation Task Group reviewed the design equation to determine if higher operating pressurescould be used in plastic piping systems. Members felt the performance of our pipe resins was not truly reflected by the design equation. It was generally accepted that the long-term properties of modern resins far surpassed those of older resins. Major considerations were new equations being developed and selection of an appropriate design factor.Improved pipe performanceMany utilities monitored the performance of plastic pipe resins. Here are some of the long-term tests used and the kinds of performance change they have shown for typical gas pipe resins.Elevated temperature burst testThey used tests like the Elevated Temperature Burst T est, inwhich the long-term performance of the pipe is checked by measuring the time required for formation of brittle cracks in the pipe wall under high temperatures and pressures (often 80 degrees C and around 4 to 5-MPa hoop stress). At Consumers Gas we expected early resins to last at least 170 hrs. at 80 degrees C and a hoop stress of 3 MPa. Extrapolation showed that resins passing these limits should have a life expectancy of more than 50 yrs. Quality control testing on shipments of pipe made fromthese resins sometimes resulted in product rejection for failure to meet this criterion.At the same temperature, today’s resins last thousands of hours at hoop stresses of 4.6 MPa. Tests performed on pipe made from new resins have been terminated with no failure at times exceeding 5,700 hrs. These results were performed on samples that were squeezed off before testing. Such stresses were never applied in early testing. When extrapolated to operating conditions, this difference in test performance is equivalent to an increase in lifetime of hundreds (and in some cases even thousands) of years.Environmental stress crack resistance testSome companies also used the Environmental Stress Crack Resistance test which measured brittle crack formation in pipes but which used stress cracking agents to shorten test times.This test has also shown dramatic improvement in resistance brittle failure. For example, at my company a test time of more than 20 hrs. at 50 degrees C was required on our early resins. Today’s resins last well above 1,000 hrs. with no failure.Notch testsNotch tests, which are quickly run, measure brittle crack formation in notched pipe or molded coupon samples. This isimportant for the newer resins since some other tests to failure can take very long times. Notch test results show that while early resins lasted for test times ranging between 1,000 to 10,000 min., current resins usually last for longer than 200,000 min.All of our tests demonstrated the same thing. Newer resins are much more resistant to the growth of brittle crack than their predecessors. Since brittle failure is considered to be the ultimate failure mechanism in polyethylene pipes, we know that new materials will last much longer than the old. This is especially reassuring to the gas industry since many of these older resins have performed very well in the field for the past 25 yrs. with minimal detectable change in properties.While the tests showed greatly improved performance, the equation used to establish the pressure rating of the pipe is still identical to the original except for a change in 1978 to a single design factor for all class locations.To many it seemed that the methods used to pressure rate our pipe were now unduly conservative and that a new design equation was needed. At this time we became aware of a new equation being balloted atISO. The methodology being used seemed to be a more technically correct method of analyzing the data and offered a number of advantages.Thermal Expansion of Piping and Its CompensationA very relevant consideration requiring careful attention is the fact that with temperature of a length of pipe raised or lowered, there is a corresponding increase or decrease in its length and cross-sectional area because of the inherent coefficient of thermal expansion for the particular pipe material. The coefficient of expansion for carbon steel is 0.012 mm/m?Cand for copper 0.0168mm/m?C. Respective module of elasticity a re for steel E = 207×1.06kN/m2 and for copper E = 103×106 kN/m2. As an example, assuming a base temperature for water conducting piping at 0?C, a steel pipe of any diameter if heated to 120?C would experience a linear extension of 1.4 mm and a similarly if heated to copper pipe would extend by 2.016 mm for each meter of their respective lengths. The unit axial force in the steel pipe however would be 39% greater than for copper. The change in pipe diameter is of no practical consequence to linear extension but the axial forces created by expansion or contractionare con- siderable and capable of fracturing any fitments which may tend to impose a restraint;the magnitude of such forces is related to pipe size. As an example,in straight pipes of same length but different diameters, rigidly held at both ends and with temperature raised by say 100?C, total magnitude of linear forces against fixed points would be near enough proportionate to the respective diameters.It is therefore essential that design of any piping layout makes adequate com- pensatory provision for such thermal influence by relieving the system of linear stresses which would be directly related to length of pipework between fixed points and the range of operational temperatures.Compensation for forces due to thermal expansion. The ideal pipework as far as expansion is concerned, is one where maximum free movement with the minimum of restraint is possible. Hence the simplest and most economical way to ensure com- pensation and relief of forces is to take advantage of changes in direction, or where this is not part of the layout and long straight runs are involved it may be feasible to introducedeliberate dog-leg offset changes in direction at suitable intervals.As an alternative,at calculated intervals in a straight pipe run specially designed expansion loops or “U” bends should be inserted. Depending upon design and space availability, expansion bends within a straight pipe run can feature the so called double offset “U” band or thehorseshoe typ e or “lyre” loop.The last named are seldom used for large heating networks; they can be supplied in manufacturers’ standard units but require elaborate constructional works for underground installation.Anchored thermal movement in underground piping would normally be absorbed by three basic types of expansion bends and these include the “U”bend, the “L”bend and the “Z”bend.In cases of 90 changes indirection the “L” and “Z”bends are used.Principles involved in the design of provision for expansion between anchor points are virtually the same for all three types of compensator. The offset “U” bend is usually made up from four 90° elbows and straight pipes; it permits good thermal displacement and imposes smaller anchor loads than the other type of loop. This shape of expansion bend is the standardised pattern for prefabricated pipe-in-pipe systems.All thermal compensators are installed to accommodate an equal amount of expansion or contraction; therefore to obtain full advantage of the length of thermal movement it is necessary to extend the unit during installation thus opening up the loop by an extent roughly equal the half the overall calculated thermal movement.This is done by “cold-pull” or other mechanical means. The total amount of extension between two fixed pointshas to be calculated on basis of ambient temperature prevailing and operational design temperatures so that distribution of stresses and reactions at lower and higher temperatures are controlledwithin permissible limits. Pre-stressing does not affect the fatigue life of piping therefore it does not feature in calculation of pipework stresses .There are numerous specialist publication dealing with design and stressing calculations for piping and especially for proprietary piping and expansion units; comprehensive experience back design data as well as charts and graphs may be obtained in manufacturers’publications, offering solutions for every kind of pipe stressing problem.As an alternative to above mentioned methods of compensation for thermal expansion and useable in places where space is restricted, is the more expensive bellows or telescopic type mechanical compensator. There are many proprietary types and models on the market and the following types of compensators are generally used.The bellows type expansion unit in form of an axial compensator provides for expansion movement in a pipe along its axis; motion in this bellows is due to tension or compression only.There are also articulated bellows units restrained which combine angular and lateral movement; they consist of double compensator units restrained by straps pinned over the center of each bellowsor double tied thus being restrained over its length.Such compensators are suitable for accommodating very pipeline expansion and also for combinations of angular and lateral movements.层流与紊流有两种完全不同的流体流动形式存在，这一点在1883年就由Osborne Reynolds 用试验演示证明。
给排水工程外文翻译
给排水工程外文翻译 Final approval draft on November 22, 2020Short and Long Term Advantage roof drainage design performanceDecade has witnessed great changes in the design of the roof drainage system recently, particularly, siphon rainwater drainage system has been gradually improved, and there is likely to be the key application. At the same time these changes, urban drainage system design has undergone tremendous changes, because the scope of a wider urban drainage system design for sustainable development, as well as people for climate change flooding more attention. The main contents of this article is how to design roof drainage systems and make a good performance. Special attention is how to get rid of bad habits already formed the design, but also need to consider innovative roof drainage system, such as green roofs and rainwater harvesting systems.Practical application: In the past few years, the design of the roof rainwater drainage system has undergone tremendous changes. On large buildings, siphon rainwater drainage technology has been very common, as well as green roofs because it is conducive to green development, being more and more applications. Taking into account the ongoing research, this article focuses on how to effectively design a variety of roof rainwater drainage system, and make it achieve the desired design effect.1. IntroductionIn the past decade, the city and the water drainage system design has been widely accepted thinking about sustainable urban drainage system, or the optimal management direction. The main principles of the design of these systems is both a local level in line with the quality of development, but also to create some economic benefits for the investors. This principle has led to the development of new changes in the sump. Although the application of such a device is gradually reduced, but the urban environment relatively high demand areas still require 100% waterproof and rapid drainage, such as the roof. Typically roof drainage system in the design, construction and maintenance has not been given due attention. Although the drainage system investment costs account for only a small portion of the total construction investment, but not able to judge the loss caused by poor design.There are two different forms of roof drainage system design methods, namely the traditional and siphon method. Traditional systems rely on atmospheric pressure work, the drive ram affectedsink flow depth. Therefore, the conventional roof drainage systems require a relatively large diameter vertical drop tube, prior to discharge, all devices must be connected to the groundwatercollection pipe network. In contrast, siphonic roof drainage pipe systems are generally designed to full flow (turbulent flow meansthat require less exhaust pipe), which will form a negative pressure, the larger the higher flow rate and pressure head. Typically siphon system requires less down pipe work under negative pressure to the water distribution network can mean higher altitude work, thereby reducing the amount of underground pipe network.Both systems consists of three parts: the roof, rainwater collection pipes, pipe network.All of these elements are able to change the water pressure distribution system. This section focuses on the role and performance of each part. Due to the principle of siphon system has not been well understood, resulting argument is relatively small, this article will highlight siphon system.2. RoofThe roof is usually designed by the architect, designer and not by the drainage design. There are three main roof.2.1 Flat roofFlat roofs are used in industrial buildings less rainfall regions and countries. This roof is not completely flat, but lower than the minimum roof slope may require. For example, the United Kingdom require maximum slope of 10 °. Setting minimum slope in order to avoid any unnecessary water.Despite the flat roof if it is not properly maintained will have more problems, but it will reduce the dead zone within the building, and the ratio of sloping roofs in favor of indoor air.2.2 sloping roofsMost residential and commercial buildings are pitched roof, inclined roof is the biggest advantage can quickly drain, thereby reducing leakage. In temperate regions, we need to consider carrying roof snow load. Once it rains, rainfall through the sloping roofs can be determined by calculation. When rainfall data can be used, you can use the kinematic theory to solve such problems.2.3 green roof (flat or inclined)It can prove roof is the oldest green roofs, including rainfall can reduce or disperse roof planted with plants. It can be planted with trees and shrubs roof garden, it can also be a vegetated roof light carpet. Wherein the latter technique has been widely used. Some of these applications tend to focus on aesthetic requirements and are often used in green development. Since the aesthetic requirements and pressure requirements, as well as green roofs thermal insulation function, reduce the heat island effect, silencer effect, extend the life of the roof.Green roofs in Germany, the most widely used, followed in North America, but to consider the impact on the aesthetics. Germany is by far the most experienced countries in the 19th century have practical application, then as an alternative to reduce the risk of fire tarroof an option in urban areas. Germany is currently the main research question on the cultivation of other issues to consider smaller cities. A study from 1987 to 1989, was found packed with 70 mm thick green roof can be reduced by 60% -80% of heat loss. In a Canadianwork computer model based on the roof indicates that as long as the sump, the area can reach 70% of the roof area can be reduced by 60 percent in one year, the same model was also used for artificial rainfall, which the results indicate that rainfall in the catchment season helps to drain away rainwater.However, none of these studies show that green roofs can play a useful role in the rainfall season, or how high collection efficiency of water supply. The United States did some tests, as long as the green roofs regular watering, can reduce 65 percent of the runoff ina rainfall. America's most authoritative green roof guidelines by the New Jersey state environmental agencies promulgated. The mainprinciple is to solve the structural problems of light, and how can the normal drainage after two years.Rainfall period is based on the probability of failure is determined. The system is typically based on rainfall during rainstorms two minutes, two minutes, have a choice. Although this model will get more traffic, but there is no other better alternative. Studies have shown that the traditional model is applied to study green roofs are premature.Loss factor than traditional roof records should be small, about 98.7%.Peak flow will be reduced, although not penetrate, the surface roughness but also have a significant impact.Concentrated rainfall than two minutes for a long time,especially for large roof areas, such as public buildings, commercial buildings, industrial buildings.Urban drainage design should also consider other factors, for a complex system, a green roof in a rain is not enough. Water flow duration curve shows a longer than traditional systems. And two independent and will affect between is possible, which requires a more precise time period.3. Rainwater CollectorBasic requirements rainwater collector is designed to be able to accommodate rainfall rainstorms. Although it is possible to make a slightly inclined roof drainage purposes, but the nature of the construction industry and building settlement will become flat roofTypically, the tank is placed in a horizontal, sectional view of the water is outwardly inclined, which the role of hydrostatic.3.1 drain outletAnalyzing rainwater collector has sufficient volume is the key to the sump outlet external setting conditions. Also affect the flow rate into the storm water drainage system piping, but also affect the depth of the water catchment. Although the depth of the sump will not bring any particular problems, but too deep can cause excessive sump.Numerous studies in the 1980s showed that the flow of conventional roof drainage system outlet can be divided into two cases. It depends on the size of the depth and size of the outlet. When the water depth is less than half the diameter of the outlet, the flow of the first type, and the outlet of the flow can be calculated by an appropriate equation; water depth increases, exports are slowly clogging the flow will become another form forms, at the same time, the flow of exports can be obtained through other equations. While conventional roof drainage systems are designed to be free-draining, but may cause limitations encountered in the design of the flow is not free. In this case, it will require additional depth.Siphon roof drainage systems, the outlet is designed to be submerged stream. In this case, the depth of the outlet of the decision is more complicated, because the design of the sump depends on the flow. Recent studies have shown that conventional roof drainage systems use a variety of non-standard catchment, their depth and height, bigger than the diameter of the outlet. This will eventually result in a siphon effect. For a given catchment, the flow depends on the starting end of the drop tube diameter. A similar phenomenon has also been used to study the standard catchment, in these circumstances, only limited siphon action occurs within relatively close distance from the exit.3.2 tank flow classificationIn the complex flow sump outlet flow classification, can be seen from Table 2a, the flow will be uniform layering, regardless of whether the same inlet flow. Table 2b and 2c show, exportdistribution will greatly influence the flow.When the outlet is not a free jet, sump outlet complex flow classification is difficult to describe. Because each catchment tank pressures are likely to be merged. For example, the siphon tube system design point is at near full jet outlet flow classification depends on the energy loss of each branch.3.3 hydrostatic sectionalSump shape of the water surface in the canal can be classified according to the flow equation. In most cases, a low flow rate meansthat there is less friction loss, if exports are free jet, thefriction loss is negligible cross-section through the hydrostatic equation 1 to determine the horizontal distance.Where Q-- flow (m3 / s)T- surface width (m)g- acceleration of gravity (m / s2)F- flow area (m2)Equation 1 can not be ignored when the friction required to correct (or very long pipe velocity is large), or not a free jet.3.4 The current design methodsThe previous discussion has highlighted the main factors that should be considered with sink design. However, without the help of a certain number of models, computing hydrostatic sectional roof drainage system, the volume of the sump is possible. This large commercial and manufacturing industry, is a development opportunity, you can merge several kilometers of water routes. Thus, the conventional drainage system sump design methods are mainly based on experience, and assume that exports are free jet.Sump location in the building, it may cause the example to fail. Different interface sumpExcept in the case cited above, but also allows designers to use empirical data.3.5 Digital ModelLarge number of digital models can be used to accurately describe the flow of any form of catchment tank, regardless of whether the roof flows stable. An example of this model is a combination of roof space model. This model enables users to classify different aspects of the data indicated, includes: details of the rains, the roof surface drainage and other details. Kinematics have also been used to study rainwater tank to flow from the research collection. A typical method is based on open system to solve a basic problem of spatial mobility. This model automatically resolve the sump outlet flow situation, but also to deal with the case of free jet can also be simulated space limited mobility and submerged discharge. Output values include depth and flow rate.Currently, the model is essentially just a variety of research tools, but also through practical engineering test. However, we should face up to the various role models.4 pipe systems groupComposition in the form and scope of the tube group determinesthe roof drainage system relies mainly on the traditional system or siphon action.4.1 Traditional stormwater systemsConventional roof drainage systems, the ground plane is generally vertical pipe-line network, connected to the sump outlet and underground drainage systems, critical systems as well as compensating tube. It should be emphasized that the angle between the ground and the compensating tube is less than 10 °. Capacity of the entire system relies mainly on the outlet tube instead of down.Flow vertical tube is usually free-flowing, full of only 33%, the efficiency depends on the excess length of the tube. If the drop tube long enough (typically greater than 5m), there may be an annular flow. Similarly, under normal circumstances flow compensation pipe is free-flowing, full of up to 70%. Such designed process both for the design, various equations can also be used.4.2 Siphon roof drainage systemIn contrast with the traditional drainage systems, Siphon roof drainage system relies on air flow outside the system, and the tubeis full pipe flow stream.The designs are usually made on the assumption that the design of heavy rain, the system can quickly siphon discharge rainwater. This assumption allows the application of hydrostatic siphon system theory. Often used steady flow energy equation. While this approach ignores the small amount of energy loss at the entrance, but after the experiment showed that there are still conducive to practical use.However, steady-state design methods in the siphon system is exposed to rain when the system does not meet the standard requirements or changes in rainfall intensity is large is not applied. In the first case, there will be some mixing of air quality, annular flow occurs. These problems are not integrated in the system when more serious. Because usually designed rains are common, it is clear now design methodology over time may not apply to siphon system. This is a major disadvantage, because the design of the main problem isthe noise and vibration problems.Despite the disadvantages of the prior design approach, but a lot of the world's very few engineering failure reports. When a failure occurs, most likely for the following reasons:An incorrect understanding of the operation pointsSubstandard materials listInstallation defectsMaintenance mismanagementTo overcome these disadvantages, we have recently launched aseries of research projects, to discuss the siphon system, and the development of digital models. From this work we learn a lot.In contrast with conventional design methods of some assumptions, siphon system mainly has the following aspects:1) non-flow system of full flow2) levels of certain pipe-flowing full pipe flow3) full pipe flow downstream propagation through a vertical pipe, riser, etc.4) the inner tube flow occurs over the vertical section, the system to reduce the pressure5) downward tube is full pipe flow, there will be air lock6) appears completely siphon action until well into the air system is lower than a certain levelTable 4a column data indicate that below the design point, the system will siphon unstable flow, depth of the water collecting tank is insufficient to maintain the siphon action. Table 4b show that the unsteady flow in siphon system when it will appear.Table 5 lists the data output of a digital model. It can be seen that the model can accurately describe the siphon action, siphon and steady state, the data also show that the model can accurately describe the complex siphon action.5 ConclusionThis article has illustrated the critical roof drainage systems, but these are often overlooked in the urban drainage system design. This article also shows that the design process is a complex process, rely mainly on the performance of exports. The following conclusions are based on the design summed up:1) Run depend on three interacting parts: the roof, sump, water pipes2) Green roofs can reduce traffic and beautify the city3) the export performance of the system is essential4) siphon drainage system have a greater advantage in large-scale projects, but must be considered high maintenance costs5) Design siphon drainage system should consider additional capacity and operational issuesAlthough the green roof is a more attractive option, but the traditional roof of a building in the country will continue to dominate. Green roofs will be gradually developed, and gradually been widely accepted. Similarly, the roof drainage system shown effective that it will continue to play a huge role in the commercial building drainage systems.Roof drainage system of the greatest threats from climate change, existing systems tend to be not simply aging; rainfall patterns of change will result in inefficient operation, self-cleaning rate will be reduced. Changes in wind speed and the roof will also accelerate the aging of the roof, it is necessary to carry out maintenance. Taking into account the climate change, the increase in materials, roof collected rainwater will be more extensive. Currently, the amount of rain around the globe per person per day 7-300 liters in the UK, with an average consumption of 145L / h / d, of which onlyabout one liter is used by people, about 30 per cent of the toilet, study shows If water shortage, rainwater collected on the roof of developed and developing countries are recommended approach.屋顶排水设计性能的近期与远期优势最近十年见证了屋顶排水系统设计方面的巨大变化，特别的是，虹吸雨水排水系统已经得到逐步改善，并且有可能得到重点应用。
给排水专业英语课文翻译
There are several species of bacteria that are widely found in the aquatic environment but so not normally cause illness in the immuno-competent. They are not therefore particularly associated with health problems from drinking-water. It is important to be aware of them nevertheless, as they have occasionally been associated with disease where people may already be ill with other conditions or their immune system is reduced and unable to cope (Dufour 1990).They are usually known as environmental bacteria, but I have also come across the terms adventitious or heterotrophic in this context (although heterotrophic strictly means they get their source of energy and cellular carbon from the oxidation of organic material, that is, by feeding on plants or animals-rather than photosvnchesis). Where laboratories carry out plare counts, it is often these bacteria that are cultured. There will be many different types of environmental bacturia but the imporiant ones for drinking-water safety are listed here.AeromonasAeromonas are commonly found in both fresh and salt waters. There are several species, each one favouring a particular environmental niche. Aeromonas bydropbila is found mainly in clean river water, Aeromonas sobria in stagnant water and Aeromonas caviae in marine water. They are so common that people have tried to use them in rivers as indicators of pollution. They are known to cause diarrhoea and infection in soft tissue where damaged skin comes into contact with contaminated river or lake water.Aeromonas caviae is the one most commonly associated with diarrhoea. Diarrhoeal infection is usually mild, although more severe symptoms have occasionally been known, including bloody diarrhoea and chronic colitis (inflammation of the colon).Aeromonas have been found in treated chlorinated water and sometimes, there is re-growth in the distribution pipes. Chlorine only appears to have a temporary effect on them and this may mean that it stops them from reproducing but does not kill them. If left (presumably so they can get their breath back and have a bit of a rest after the chlorine attack) they can continue as normal.有一些种类的细菌在水生环境中被发现,但通常不引起疾病immuno-competent。
给水排水工程专业英语文献翻译原文第一篇
Abbreviations: ADF, Aerobic Dynamic Feeding, also designated as “feast and famine”; CSTR, Continuous Stirred Tank Reactor; C/N, Carbon to nitrogen ratio; HAc, Acetic acid; HB, Hydroxybutyrate; HBut, Butyric acid; HLac, Lactic acid; HProp, Propionic acid; HV, Hydroxyvalerate; HVal, Valeric acid; HRT, Hydraulic Retention Time; OUR, Oxygen Uptake Rate; PHA, Polyhydroxyalkanoate; qP, Maximum specific polymer storage rate; -qS, Maximum specific substrate uptake rate; SBR, Sequencing Batch Reactor; SRT, Sludge Retention Time; TOC, Total Organic Carbon; VFA, Volatile Fatty Acid; VSS, Volatile Suspended Solid; VSSmax, Volatile Suspended Solids at the time of maximum polymer accumulation; X, Active Biomass; Xi, Initial active biomass concentration; YO2/X, Respiration yield, in Cmmol/Cmmol VFA; YP/S, Polymer storage yield, in Cmmol HA/Cmmol VFA; YX/S, Growth yield in Cmmol X/Cmmol VFA
给水排水工程专业英语文献翻译译文第一篇
一种利用蜜糖废水产生PHA的侧流工艺的建立方法摘要试验建立了一种利用蜜糖废水生产聚羟基烷酸脂（PHA）的三阶段过程。
该过程包括（1）糖蜜废水酸酵解，（2）PHA富集菌的筛选，（3）利用富集完毕的污泥和酵解之后的糖蜜废水批次累积PHA。
在发酵阶段，试验评估了PH（5~7）对有机酸型体分布以及产率的影响。
PH较高时乙酸和丙酸为主要产物，然而较低的PH值有利于丙酸和戊酸的产生。
试验评估了利用乙酸盐和发酵糖蜜废水为基质筛选的两类菌群的PHA积累能力。
考察了有机酸型体分布对利用醋酸盐筛选菌群产生的多聚体的组成以及产率的影响。
PHA富集产率在0.37到0.50CmmolHA/Cmmol VFA之间变化。
试验观察到了被利用有机酸的类型和多聚物成分的一种直接关系。
在糖蜜废水中，低氨氮浓度（0.1Nmmol/l）促进了PHA 的储存（0.59 Cmmol HA/Cmmol VFA）。
此外，试验建立了一种控制反应器运行利用发酵糖蜜废水筛选PHA富集菌群的方法。
利用高有机负荷以及低氨氮浓度选择了一种具有稳定储存PHA能力的菌群，富集产率达到0.59Cmmol HA/Cmmol VFA)，这一能力与醋酸盐筛选菌相似。
前言聚羟基烷酸脂被认为是优良的可生物降解塑料的候选者。
这类含有多种单体组分具有热塑性的多聚物是被细菌作为能量和碳储存物质的。
它们的结构特性与聚丙烯的结构性质一致，同时又具有诸多优势：可生物降解、可生物相容、能进一步由可再生碳源产生从而使可持续生产过程成为可能。
然而，PHAs与石化工业衍生的塑料制品在成本上相当大的差异成了这类高聚物部分替代后者的阻碍。
目前，商业可行的PHAs是由纯菌（野生的和基因重组的菌种）和纯底物（通常很昂贵）工业化生产而来。
PHAs的价格主要取决于底物成本，约占总成本的40%（Choi和Lee，1997）。
最近十年来，一系列低成本的碳源基质（例如淀粉、木薯粉水解物、乳清和蜜糖）在纯菌生产PHA过程中得到检验。
给排水专业毕业设计翻译中英文对照(20页)
Oxidize ditch craft in dirty water handle of application and development Summary: This text expatiated primarily the Carrousel oxidizes the construction, craft mechanism of the ditch and circulate the problem exsited in the process with the homologous the method of solution.Finally, introduce the Carrousel oxidize the latest research progress of the ditch and pointed out the future and main research direction.Key phrase: The Carrousel oxidizes ditch divideds by the phosphor takes off the nitrogen construction mechanism Application and Development of Carrousel Oxidation Ditch Process on Wastewater TreatmentAbstract: The structure and the techniques of carrousel oxidation ditch process on nitrogen and phosphor removal are introduced in this paper. The problems inrunning and their corresponding resolvent are also pointed. At last, The authorshowed the up to date research improvement and the mainly future research dire-ction.Key words: Carrousel; oxidation ditch; nitrogen and phosphor removal; structure;techniques1. ForewordOxidize the ditch( oxidation ditch) again a continuous circulation spirit pond( Continuous loop reactor), is a live and dirty mire method a kind of to transform.Oxidizing the dirty water in ditch handles the craft be researched to manufacture by the hygiene engineering graduate school of Holland in the 50's of 20 centuries success.Since in 1954 at Dutch throw in the usage for the very first time.Because its a water fluid matter good, circulate the stability and manage convenience etc. technique characteristics, already at domestic andinternational and extensive application in live the dirty water to is dirty to manage aqueously with the industry[1].Current application than oxidize extensively the ditch type include:The ( Pasveer) oxidizes the ditch, the ( Carrousel) oxidizes the ditch, ( Orbal) oxidizes the ditch, the type of T oxidizes the ditch( three ditch types oxidize the ditch), the type of DE oxidizes the ditch to turn to oxidize the ditch with the integral whole.These oxidize the ditch because of the difference of esse in construction with circulating, therefore each characteristics[2].This text will introduce construction, mechanism, existent problem and its latest developments that Carrousel oxidize ditches primarily.2. The Carrousel oxidizes the construction of the ditchThe Carrousel oxidize the ditch to be researched to manufacture by Dutch DHV company development in 1967.Oxidize the last the company of DHV in foundation of the ditch in the original Carrousel to permited specially the company EIMCO to invent again with its patent in the United States Carrousel 2000 system( see the figure ), realizes the living creature of the higher request takes off the nitrogen with divided by the function of .There has been in the world up to now more than 850 Carrousels oxidize the ditch with the Carrousel 2000 system are circulating[3].From diagram therefore, the Carrousel oxidizes the ditch the usage the spirit of that definite direction control with shake up the device, face to mix with the liquid deliver the level speed, from but make drive the liquid of admixture that shake up is in oxidize ditch shut match outlet circulate flow.Therefore oxidize the ditch have the special hydraulics flows the , current complete mix with the characteristics of the type reactor, have the characteristics that push the flow type reactor again, the ditch inside exsits obviously of deliquescence oxygen density steps degree.Oxidizing the ditch crosssection is rectangle or trapezoids, the flat surface shape is many for oval, the ditch internal water is deep general for 2.5 ～4.5 ｍ, the breadth is deep compare for 2:1, also have the deep water amount to 7 ms of, ditch inside average speed in water current is 0.3 ms/ s.Oxidize ditch spirit admixture equipments contain surface spirit machine, the spirit of turn to brush or turn the dish and shoot to flow the spirit machine, pipe type spirit machine with promote take care of type spirit machine etc., match with in recent years usage still contain underwater push machine[4~6].3. The Carrousel oxidizes the mechanism of the ditch3.1 The Carrousel oxidizes the ditch handles dirty and aqueous principleThe at the beginning common Carrousel oxidizes the dirty water in inside in craft of the ditch direct with dirty mire in reflux together enter oxidize the ditch system.The surface spirit machine makes fuse in the liquid of admixture the density of the oxygen DO increases about 2 the 3 mgs/ L.Under this kind of well the term of the oxygen , the microorganism gets the enough deliquescence oxygen comes and go to divided by the BOD;At the same time, the ammonia were too oxidized nitrate with second nitrate, this time, mix with the liquid be placed in the oxygen appearance.In the spirit machine downstream, after water current be become by the swift flow appearance of the spirit District of even flow the appearance, the water current maintains in the minimum current velocity, guaranteeing the live and dirty mire be placed in the floats the appearance.( average current velocity>0.3 ms/ s)Oxidize microbially the process consumed to fuse the oxygen in the water, until the value of DO declines for zero, mixing with the liquid report the anoxia appearance.Versa nitric that turn the function through anoxia area, mix with the liquid enter to have the oxygen area, completing once circulating.That system inside, theBOD declines the solution is a continuous process, the nitric turns the function to turn with the versa nitric the function take place in same pond.Because of structural restrict, this kind of oxidize the ditch although can then valid whereabouts BOD, divided by the phosphorus take off the nitrogenous ability limited[7].For the sake of the acquisition better divided by the phosphorus take off the nitrogenous result, Carrousel 2000 systems increased a oxygen District before common Carrousel oxidize ditch with the unique oxygen area.( call again that the versa nitric in front turns the area)The dirty mire in all refluxes enters the anaerobic District with 10-30% dirty water, can under the anoxia with 10-30% carbon source term complete remaining of dirty mire in reflux inside nitric acid nitrogen to versa nitric to turn, creates for the unique oxygen pond of hereafter unique oxygen term.At the same time, anaerobic District inside of concurrently the sex germs convert the dissolubility BOD VFA, the germ acquire the VFA its assimilation PHB, the energy source needed solves in the phosphoric water and cause phosphatic releasing.The anaerobic District a water enters the inner part installs the unique oxygen area that have the mixer, the so-called unique oxygen is a pond inside to mix with liquid since have no the numerator oxygen, also have no the compound oxygen( nitric acid root), the here unique oxygen environment is next,70-90% dirty water can provide the enough carbon source, can make the germ of released the phosphorus well.The unique oxygen area connects behind the common Carrousel oxidizes the ditch system, further completing to do away with the BOD and take off the nitrogen with divided by the phosphorus .Finally, mix with the liquid transfer the dirty mire inside in oxidize ditch enrich oxygen area eject, while enriching the oxygen environment germ surfeit, phosphorus from the water, ejecting the system with the dirty mire in surplus.Like this, in Carrousel 2000systems, than completed to do away with the BOD, COD with take off at the same time goodly the nitrogen divided by the phosphorus .Synthesizing and dirty water in the river City , long sand City decontamination center[s of the dirty the factory of water in the first in Kunming of adoption that crafts handles the movement result of the factory therefore:Through Carrousel 2000 system after handling, the BOD, COD, SS does away with the rate to all come to a 90% above, the TN does away with the rate comes to a 80%, the TP does away with the rate to also come to a 90%.3.2 The Carrousel oxidizes the ditch divideds by the phosphorus takes off the nitrogenous influence factor.Affecting the Carrousel oxidizes the ditch divideds by the phosphoric factor is dirty mire , nitrate density and quality densities primarily.The research expresses, being total and dirty mire as 11% that a hour biggest phosphorus 4% with deal is its fuck dirty mire deal within live and dirty mire, keep for the the germ physical endowment measures, but when dirty mire over 15 d hour dirty mire the inside is biggest to contain the obvious descent in deal in phosphorus , canning not reach the biggest divideding by the result of phosphorus on the contrary.Therefore, prolong persistently the dirty mire ( for example 20ds,25ds,30ds) is to have no necessary, proper choose to use within the scope of 8~15 d.At the same time, high nitrate density with low quality density disadvantage in divided by the process of phosphorus .Affecting the Carrousel oxidizes the ditch takes off the nitrogenous and main factor is DO, nitrate density and carbon source densities.The research expresses, oxidizing the ditch inside exsits deliquescence oxygen density steps degree namely the good oxygen area DO attains 3~3.5 mgs/ L, the anoxia area DO attains 0~0.5 mgs/ L is a prior condition to take place nitric turn reaction and versa nitricsturn the reaction.At the same time, ample carbon source and higher C/ the N ratio benefits to take off to complete nitrogenously[7].4. The Carrousel oxidizes problem and solution methods of the ditch esse.Though the Carrousel oxidizes the ditch has a water fluid matter good, the anti- pounds at the burthen ability strong, divided by the phosphorus take off the nitrogen efficiency. But, in physically of movement process, still exsits a series of problem.4.1 Dirty mire inflation problemWhen discard the aquatic carbohydrate more, the N, P contains the unbalance of deal, the pH value is low, oxidizing the dirty mire in inside in ditch carries high, fuse the oxygen density the shortage, line up the mire not etc. causes easily dirty mire in germ in form in silk inflation;Not the dirty mire in germ in form in silk inflation takes place primarily at the waste water water temperature is lower but the dirty mire carries higher hour.The microbial burthen is high, the germs absorbed the large quantity nourishment material, is low because of the temperature, metabolism the speed is slower, accumulating the rises large quantity is high to glue sexual and many sugar materials, making the surface of the live and dirty mire adhere to the water to increase consumedly, SVI the value is very high, becoming the dirty mire inflation.Cause that aim at the dirty mire inflation, can adopt the different counterplan:From the anoxia, water temperature high result in of, can enlargement tolerance or lower into the water measures to alleviate burthen, or the adequacy lowers the MLSS( control dirty mire reflux measure), making need the oxygen measures decrease;If the dirty mire carries high, can increase MLSS, to adjust the burthen, necessity the hour can stop into the water, stuffy a period of time;Can pass the hurl add the nitrogen fertilizer, phosphorus fatty, adjust the admixturenourishment in the liquid material equilibrium( BOD5:N:P=100:5:1);The value of pH over low, can throw to add the lime regulate;Bleach the powder with the liquid chlorin( press to fuck 0.3% of the dirty mire~0.6% the hurl adds), can repress the silk form germ breed, controling the dirty mire in combinative water inflation[11].4.2 Foam problemBecause entering to take the grease of large quantity in the water, handling system can't completely and availably its obviation, parts of greases enriches to gather in in the dirty mire, through turn to brush the oxygen agitation, creation large quantity foam;The mire is partial to long, the dirty mire is aging, and also easy creation foam.Spray to pour the water or divided by with the surface the of do away with the foam, in common use divided by the an organism oil, kerosene, the oil of silicon, throw deal as 0.5~1.5 mgs/ L.Pass to increase dirty mire in pond in spirit in density or adequacies let up the tolerance of , also can control the foam creation effectively.When contain the live material in surface in the waste water more, separate with the foam easily and in advance method or other methods do away with.Also can consider to increase to establish a set of divideding by the oil device moreover.But enhance most importantly the headwaters manage, reducing to contain the oil over the high waste water and other poisonous waste water of into[12].4.3 Float the problem on the dirty mireWhen contain in the waste water the oil measures big, whole system mire quality become light, can't like to control very much in operate process its at two sink the pond stop over time, resulting in the anoxia easily, producing the corrupt and dirty mire ascend to float;When spirit time over long, take place in pond the high degree nitric turn the function, making nitrate density high, at two sink theversa nitric in easy occurrence in pond turn the function, creation nitrogen spirit, make dirty mire ascend float;Moreover, contain the oil in the waste water?Take place the dirty mire ascend after floating should pause enter water, broke off or dirty mire in clearance, judge the clear reason, adjust the operation.The dirty mire sinks to decline the sex bad, can throw to add of oagulate or sloth materials, the improvement precipitates the sex;Such as enter the water carries big let up into the water measures or the enlargement reflux measures;Such as the dirty mire grain small lower the spirit machine turn soon;If discovers versa nitric turning, should let up the toerance , enlarge the reflux or row the mire measures;If discover the dirty mire is corrupt, should enlargement tolerance, the clearance accumulates the mire, and try the ameliorative pond internal water dint term[12].4.4 Current velocity is not all and the dirty mire sinks to accumulate the problemIn Carrousel oxidize ditch, for acquiring its special admixture with handles result, mix with liquid must with certain current velocity is in ditch circulate flow.Think generally, the lowest current velocity should should attain for an average current velocity for, doing not take place sinking accumulating 0.3~0.5 ms/ s.The spirit equipments that oxidize the ditch is general to turn to brush for the spirit of to turn the dish with the spirit of , turning to brush of immerse to have no depth for 250~300 mms, turn the dish immerse to have no depth for 480~530 mms.With oxidize the ditch water the deep(3.0~3.6 ms) comparing, turn to brush occupied the deep 1/10~ in water 1/12, turned the dish to also occupy the 1/6~ only 1/7, therefore result in to oxidize the ditch upper part current velocity bigger( roughly 0.8~1.2 ms, even larger), but the bottom current velocity is very small( especially at the water is deep 2/3 or 3/4 below, mix with theliquid has no current velocity almost), causing ditch bottom large quantity accumulate the mire( sometimes accumulate the mire thickness amount to a 1.0 ms), the valid capacity that reduced to oxidize the ditch consumedly, lowered to handle result, affected a water fluid matter.Adding the top, downstream leads to flow the plank is a valid method that ameliorative current velocity distribute, increases the oxygen ability with the most convenient measure.The upper stream leads to flow the plank installs at be apart from to turn the 4.0 places( upper stream) ：dish( turn to brush) axis, lead to flow plank high degree as the deep 1/5~ in water 1/6, combine the perpendicularity install in the surface;The downstream leads to flow the plank installs at be apart from to turn dish( turn to brush) axis 3.0 ms.Leading to flow knothole material can use metals or glass steels, but regard glass steel as good.Lead to flow the plank compares with other ameliorative measure, can't not only increase the motive consumes with revolves cost, but also can still than significantly exaltation 充oxygen ability with theories motive efficiency[13].Moreover, pass in the spirit on board swim to establish the underwater push machine can also turn to the spirit of the liquid of admixture that brush the bottom low speed area circulates to flow to rise positive push function, from but the solution oxidizes the problem that low and dirty mire in current velocity in bottom in ditch sink accumulates.Establish the underwater push machine useds for exclusively the push mixs with the liquid can make movement method that oxidize the ditch much more vivid, this for economy energy, lift the high-efficiency having the very important meaning[14].5. The Carrousel oxidizes the development of the ditchBecause the dirty water handles standard inside to divided by the phosphorus take off the nitrogenous request more and more strict,the development that Carrousel further oxidized the ditch to also get.Current, the research and application includes morely below two category type:Tiny bore spirit type Carrousel 2000 systems, Carrousel 3000 system.5.1 Tiny bore spirit type Carrousel 2000 systemTiny bore spirit type Carrousel 2000 tiny bore in adoption in system spirit( provide oxygen equipments as the drum breeze machine), the tiny bore spirit machine can produce the diameter of large quantity as a surface for or so and small spirit steeping, this consumedly increases spirit bubble accumulates, undering the certain circumstance in capacity in pond make the oxygen transfer the gross measures aggrandizement.( if deep increment in pond, its spread the quality efficiency will be higher)Produce the technique ability of the factory house according to the current drum breeze machine, the valid water of the pond is deep biggest amounting to a 8 ms, therefore can select by examinations according to the different craft request the fit water is deep.The tradition oxidizes the ditch pushes to flow is to make use of to turn to brush, turn a disc or pour the umbrella type form machine realizes of, its equipments utilization is low, the motive consumes big.Tiny bore spirit type Carrousel 2000 systems then adopted the underwater pushes the way that flow, rises to dive the propeller the leaf the motivation that round creation the direct function namely in the of water, at push to flow the function to can keep dirty mire from sinking to decline effectively again at the same time.As a result, the adoption dives the propeller since lower the motive consume, making mire water got again to mixs with adequately.Seeing from water power characteristic, tiny bore spirit type Carrousel 2000 systems are wreaths form the fold flows the pond type, concurrently pushing the flow type with complete mix with the typeflows .In regard to whole oxidize ditch, can think that oxidize the ditch is a complete mix with spirit pond, its density variety coefficient smallest even can neglect to do not account, enter the water will get the dilution quickly, therefore it have the very strong anti- pounds at the burthen ability.But have oxidize ditch inside of a certain very much the some pushing the characteristic of the flow type, in the nearby district in downstream in machine in spirit inDO density higher, but along with increase with spirit machine distance continuously then the density of DO lowers continuously.( appear the anoxia area)This kind of structure method makes friendly oxygen in area in anoxia area exsited to build the thing inside , making use of its water power characteristic well, coming to an efficiently the living creature takes off the nitrogenous purpose.Tiny bore spirit type Carrousel 2000 system though have the oxygen ability strong, divided by the phosphorus take off the nitrogen effective, cover the area little with can consume low etc. advantage, it also exsits at the same time the problem that tiny bore spirit equipments maintain.Current, the service life of the local and tiny bore spirit machine is 5 years in 4~, can amount to 10 years in 8~ goodly, but with import the tiny bore spirit machine compare to still have the certain margin.The spirit machine maintains unlike the form equipments is so convenient, it need to fuck the pond talent fixs, and also is to say once the tiny bore spirit machine appears the problem to need the adoption parallel two inconvenience for or third sets to solving problem, or adopting promoting device waiting to resolving, this too will giving production with managing bringing biggest[15 16].5.2 Carrousel 3000 systemCarrousel 3000 systems are in the Carrousel 2000 systems are ex- to plus a living creature the choice the area.That living creaturechoice area is a craft to make use of high organism carries to sieve germ grow, repress silk form germ increase, increase each pollutant do away with the rate, afterward principle together Carrousel 2000 system.Carrousel 3000 system of bigger increases to express at:An is to increased the pond deep, can amount to 7.5~8 ms, united at heart circle type, the pond wall uses totally, reducing to cover the area, lowering to build the price to increases to bear the low temperature ability at the same time;( can amount to 7 ℃ )Two is the liquid of admixture that spirit equipments that skillful design, the form machine descends to install to lead to flow , the anoxia of take out , adopt the underwater propeller solution current velocity problem;Three is to used the advanced spirit controller QUTE.( it adopt the much aer kind of changing the deal control mode)Four is to adopt the integral whole turn the design, starting from the center, including below wreath form consecution craft unit:Enter the well of water with the cent water machine that used for the live and dirty mire in reflux;Difference from four-part the choice pond that cent constitute with 厌oxygen pond.This outside is a Carrousel to have three spirit machine with a prepare versa nitric turn the pond 2000 system.( such as figure 2 show)Five is tube line that the design that the circular integral whole turn to make oxidize the ditch do not need additionally, can immediately realize dirty mire in reflux allotment in different craft unit[17].6. ConclusionThe Carrousel oxidizes the ditch because of having the good a phosphorus takes off the nitrogen ability, anti- pounds at the burthen ability with circulate to manage the convenience etc. the advantage, having got the extensive application.But because of technological development with social advance, that craft is necessarily willexaltation getting further.The author thinks:The Carrousel oxidizes the future research direction of the ditch will now of main below several aspects.1 Combination living creature method, research with develop the living creature model Carrousel oxidize the ditch.Like this can not only increases the microorganism gross of the unit reactor measures, from but increases the organism carries, but also living creature oneself the inside that have places the A/ the system of O enhances to take off the nitrogen result[18].2 Increases continuously the Carrousel oxidize the microbial activity in inside in ditch.For example throw to add the EM in oxidize ditch with single mind the germ grow, throws in that the salt of iron make the microorganism tame the live char in iron, devotion in living creature to become the formation to strengthen the germ gum regiment and increases to bear the toxicity pound at etc..3 Increasing the Carrousel oxidizes the ditch equipments function with supervise and control the technique.Function that increases form machine, underwater propeller, reduce to maintain the workload;Making use of DO, etc. of ORP many targets supervises and control the technique and changes the technique of is from now on the Carrousel oxidizes ditch science circulate necessarily from it road.4 Increasing the Carrousel oxidizes the ditch resistant to cold and bear toxicity can, reduce to cover the area to build the price with the engineering.Theoretical application, deep pond in water power term with the research of the craft function is to lowers the engineering builds the price and increases resistant to cold bear the toxicity can wait to provide the possible direction.氧化沟工艺在污水处理中的应用与发展摘要：本文主要阐述了Carrousel氧化沟的结构、工艺机理、运行过程中存在的问题和相应的解决方法。
给水排水工程专业英语文献翻译原文第三篇
Journal of Membrane Science 376 (2011) 196–206Contents lists available at ScienceDirectJournal of MembraneSciencej o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /m e m s ciFouling and cleaning of RO membranes fouled by mixtures of organic foulants simulating wastewater effluentWui Seng Ang 1,Alberto Tiraferri,Kai Loon Chen 2,Menachem Elimelech ∗Department of Chemical and Environmental Engineering,P.O.Box 208286,Yale University,New Haven,CT 06520-8286,USAa r t i c l e i n f o Article history:Received 6December 2010Received in revised form 7April 2011Accepted 9April 2011Available online 20 April 2011Keywords:Reverse osmosis FoulingWastewater effluent CleaningOrganic foulantsWastewater treatment Effluent organic matter Wastewater reclamation Membranesa b s t r a c tThe fouling and subsequent cleaning of RO membranes fouled by a mixture of organic foulants sim-ulating wastewater effluent has been systematically investigated.The organic foulants investigated included alginate,bovine serum albumin (BSA),Suwannee River natural organic matter,and octanoic acid,representing,respectively,polysaccharides,proteins,humic substances,and fatty acids,which are ubiquitous in effluent organic matter.After establishing the fouling behavior and mechanisms with a mixture of organic foulants in the presence and absence of calcium ions,our study focused on the clean-ing mechanisms of RO membranes fouled by the mixture of organic foulants.The chemical cleaning agents used included an alkaline solution (NaOH),a metal chelating agent (EDTA),an anionic surfactant (SDS),and a concentrated salt solution (NaCl).Specifically,we examined the impact of cleaning agent type,cleaning solution pH,cleaning time,and fouling layer composition on membrane cleaning effi-ciency.Foulant–foulant adhesion forces measured under conditions simulating chemical cleaning of a membrane fouled by a mixture of the investigated organic foulants provided insights into the chemical cleaning mechanisms.It was shown that while alkaline solution (NaOH)alone is not effective in dis-rupting the complexes formed by the organic foulants with calcium,a higher solution pH can lead to effective cleaning if sufficient hydrodynamic shear (provided by crossflow)prevails.Surfactant (SDS),a strong chelating agent (EDTA),and salt solution (NaCl)were effective in cleaning RO membranes fouled by a mixture of foulants,especially if applied at high pH and for longer cleaning times.The observed cleaning efficiencies with the various cleaning agents were consistent with the related measurements of foulant–foulant intermolecular forces.Furthermore,we have shown that an optimal cleaning agent con-centration can be derived from a plot presenting the percent reduction in the foulant–foulant adhesion force versus cleaning agent concentration.© 2011 Elsevier B.V. All rights reserved.1.IntroductionAs demand for potable water increases worldwide,the paradigm for selecting water sources to meet this demand is transitioning from conventional sources,such as reservoirs and lakes,to less con-ventional sources,such as treated secondary wastewater effluent.In order to produce water of superior quality,the use of mem-branes in desalination and wastewater reclamation has become more widespread.Membrane fouling is a major impediment to the use of membrane technology for such applications,because fouling is inevitable.Despite research efforts to develop better anti-fouling membranes [1]and improved fouling-control strategies [2,3],membrane fouling still occurs over time.Thus,a long-term∗Corresponding author.Tel.:+12034322789;fax:+12034324387.E-mail address:menachem.elimelech@ (M.Elimelech).1Current address:Public Utility Board of Singapore,Singapore.2Current address:Department of Geography and Environmental Engineering,Johns Hopkins University,Baltimore,MD 21218,United States.solution would be to remove the foulant deposited on the mem-brane via chemical cleaning.To select the appropriate cleaning agents and adopt an effective chemical cleaning protocol for fouled membranes in wastewater reclamation,the implications of wastewater effluent characteris-tics on membrane fouling have to be well-understood.Wastewater effluent contains dissolved organic matter,commonly known as effluent organic matter (EfOM),which comprises polysaccha-rides,proteins,aminosugars,nucleic acids,humic and fulvic acids,organic acids,and cell components [2–4].Organic fouling of the RO membranes by the EfOM can be extensive since EfOM is gener-ally small enough to pass through the pores of pretreatment (MF or UF)membranes [4].In particular,recent findings suggest that while biofouling can prevail on the tail-element of the membrane module,fouling of the lead-element exposed to reclaimed water is dominated by EfOM adsorption [5].In addition,higher potential of fouling was observed for the higher molecular weight hydropho-bic/aromatic fraction of the EfOM [6,7].The presence of Ca 2+in the feed source for the RO membranes has been reported to form complexes with the constituents of EfOM,such as polysaccharidesW.S.Ang et al./Journal of Membrane Science376 (2011) 196–206197[8]and natural organic matter[9],and to significantly enhance membrane fouling.While our previous studies have addressed the fouling of RO membranes by individual organic foulant types,such as polysaccharides[10],proteins[11],and fatty acids[12],only recently have investigations reported on the effects of a combina-tion or mixture of foulants on the fouling of RO membranes[13,14].A variety of chemical cleaning agents are commonly used to clean RO membranes fouled by organic matter[15].Alkaline solutions remove organic foulants on membranes by hydroly-sis and solubilization of the fouling layer.Alkaline solutions also increase the solution pH,and,therefore,increase the negative charges and solubility of the organic foulant.Metal chelating agents remove divalent cations from the complexed organic molecules and weaken the structural integrity of the fouling layer matrix[16]. Surfactants solubilize macromolecules by forming micelles around them[17],thereby facilitating removal of the foulants from the membrane surface.In our earlier study on salt cleaning of organic matter-fouled RO membranes[18],we demonstrated that NaCl and other common inert salts can be used as an effective alternative for the cleaning of RO membranes fouled by gel-forming hydrophilic organic foulants.In the presence of a salt solution,the fouling layer swells and becomes more porous.As a result,this would facil-itate the diffusion of Na+into the fouling layer and breakup of Ca2+–alginate bonds by ion exchange.Understanding the fouling layer characteristics and the interaction of chemical agents with foulants is therefore critical for the effective cleaning of organic matter-fouled RO membranes.Atomic force microscopy(AFM)has been applied in mem-brane fouling/cleaning research to quantify intermolecular forces [10,19–21].Our research has shown that foulant–foulant inter-actions could be determined by performing force measurements using a carboxylate-modified latex colloid probe in an AFMfluid cell[10,20].The technique has been used to quantify the foul-ing behavior of a nanofiltration membrane fouled by humic acid and the cleaning efficiencies of EDTA and SDS[20],and has been extended to quantify RO membrane fouling by organic foulant in the form of alginate[10],BSA[11],and octanoic acid[12].In this study,the AFM has also been employed as an alternative tool to indicate the optimal concentration of cleaning agent for cleaning fouled membranes.The original protocol[11,12]for using the AFM has been modified to investigate the intermolecular adhesion force between different foulants.The objective of this study is to explore the mechanisms govern-ing the fouling of RO membranes by mixtures of organic foulants simulating wastewater effluent,and the ensuing chemical cleaning of the fouled membranes by cleaning agents.To make this study rel-evant to wastewater reclamation,we systematically investigate the fouling of RO membranes by each individual organic foulant type (polysaccharides,proteins,humic acids,or fatty acids)and mix-tures containing several types of organic foulants in the absence and presence of calcium ions.Cleaning experiments are performed with the fouled membranes using NaOH,EDTA,SDS,and NaCl as model alkaline solution,metal chelating agent,surfactant,and salt cleaning solution,respectively.The intermolecular adhesion forces between the different foulants and estimated aggregate sizes in foulant mixtures were used to explain the fouling mechanism of RO membranes and the cleaning behavior of a cleaning agent on the fouled membranes.2.Materials and methodsanic foulants Louis,MO),Suwannee River natural organic matter(SRNOM) (International Humic Substances Society,St.Paul,MN),bovine serum albumin(BSA)(Sigma–Aldrich,St.Louis,MO),and octanoic acid(OA)(Sigma–Aldrich,St.Louis,MO),respectively.According to the manufacturer,the molecular weight of the sodium alginate ranges from12to80kDa.Other characteristics of SRNOM,includ-ing molecular weight and mass fraction of hydrophobic NOM,can be found elsewhere[22,23].According to the manufacturer,the molecular weight of the BSA is about66kDa.BSA is reported to have an isoelectric point at pH4.7[24].Octanoic acid(Sigma–Aldrich,St. Louis,MO)was selected to model fatty acids in EfOM because of its presence in food and solubility in water(saturation concentration of4.7mM at20◦C)[12].Sodium alginate,BSA,and SRNOM were received in powder form,and stock solutions(2g/L)were prepared by dissolving each of the foulants in deionized(DI)water.DI water was supplied from a Milli-Q ultrapure water purification system(Millipore,Billerica, MA).Mixing of the stock solutions was performed for over24h to ensure complete dissolution of the foulants,followed byfil-tration with a0.45-mfilter(Durapore,Millipore,Billerica,MA). Thefiltered stock solutions were stored in sterilized glass bottles at4◦C.Octanoic acid was received in solution(≥98%concentra-tion)and was stored at room temperature.To achieve the intended octanoic acid concentration during fouling,octanoic acid was dis-solved separately for at least8h prior to fouling so that,at the initiation of fouling,octanoic acid could be introduced as a solu-tion.A few hours before the initiation of fouling,the ionic strength of the stock solution was adjusted to the same concentration as that of the feed solution(10mM)and the stock solution pH was elevated,as needed,from ambient pH of3.9–9.0by adding small amounts of1M NaOH.2.2.Chemical cleaning agentsThe chemical cleaning agents used were:NaOH(pH11.0)as an alkaline solution,certified grade disodium ethylenediaminete-traacetate(Na2–EDTA)as a metal chelating agent,certified grade sodium dodecyl sulfate(SDS)as an anionic surfactant,and NaCl as a salt cleaning solution.The agents were purchased from Fisher Sci-entific(Pittsburgh,PA)and used with no further purification.The stock chemical solutions were prepared fresh by dissolving each chemical in deionized(DI)water.The pH of the EDTA,SDS,and NaCl cleaning solutions was adjusted with1.0M NaOH as necessary.2.3.RO membraneThe relatively well-characterized thin-film composite LFC-1 membrane(Hydranautics,Oceanside,CA)was used as a model RO membrane.The average hydraulic resistance was determined to be 9.16(±0.11)×1013m−1corresponding to a hydraulic permeabil-ity of10.9(±0.13)×10−11m s−1Pa−1.The observed salt rejection was98.7–99.3%,determined with a10mM(584mg/L)NaCl feed solution at an applied pressure of300psi(2068.5kPa)and a cross-flow velocity of8.6cm/s.Membrane samples were received as dry large sheets,and were cut and stored in DI water at4◦C.The membrane has been reported to be negatively charged at solu-tion chemistries typical to wastewater effluents,with an isoelectric point at about pH4.6[25].The membrane has been reported to be coated with a neutral polyalcohol layer rich in–COH functional groups,which renders the surface less charged than the surfaces of other polyamide RO membranes without a coating layer[25,26].2.4.Crossflow test unit198W.S.Ang et al./Journal of Membrane Science376 (2011) 196–206unit consists of a membrane cell,pump,feed reservoir,temper-ature control system,and data acquisition system.The membrane cell consisted of a rectangular plate-and-frame unit,which con-tained aflat membrane sheet placed in a rectangular channel with dimensions measuring7.7cm long,2.6cm wide,and0.3cm high. Both permeate and retentate were recirculated back to the feed reservoir.Permeateflux was registered continuously by a digital flow meter(Optiflow1000,Humonics,CA),interfaced with a com-puter.Afloating disc rotameter(King Instrument,Fresno,CA)was used to monitor the retentateflow rate.The crossflow velocity and operating pressure were adjusted using a bypass valve(Swagelok, Solon,OH)in conjunction with a back-pressure regulator(U.S.Para Plate,Auburn,CA).Temperature was controlled by a recirculating chiller/heater(Model633,Polysciences)with a stainless steel coil submerged in the feed water reservoir.2.5.Fouling and cleaning experimentsThe membrane wasfirst compacted with DI water until the permeateflux became constant,followed by the initial baseline performance for1h.The membrane was then stabilized and equi-librated with a foulant-free electrolyte solution for2h.Theflux at which the baseline run was performed was predetermined so that the initialflux would drop to a specifiedflux of2.3×10−5m s−1(or 83L m−2h−1)after adding the electrolyte solution.The chemistry of the foulant-free electrolyte solution and operating conditions adjusted in this stage were similar to those used for the ensuing fouling runs.As octanoic acid takes time to dissolve completely,the mixture of organic foulant solution has to be prepared8h before the fouling run.The feed foulant solution was prepared separately in another container.The chemistry of the feed foulant solution was adjusted to be identical to that of the foulant-free electrolyte solution so that the overall ionic strength and solution chemistry would not change when the feed foulant solution was added to initiate fouling. Fouling runs were carried out for17h.At the end of the fouling run, the solution in the feed reservoir was disposed off and chemical cleaning solution was added to the feed reservoir to clean the fouled membrane.At the end of the cleaning stage,the chemical cleaning solution in the reservoir was discarded,and both the reservoir and membrane cell were rinsed with DI water toflush out the residual chemical cleaning solution.Finally,the cleaned RO membrane was subjected to the second baseline performance with DI water to re-determine the pure waterflux.The crossflow velocity throughout the experiment,except dur-ing cleaning,was maintained at8.6cm/s.The operating conditions (i.e.,initialflux,crossflow velocity,and temperature)at this stage were identical to those applied during the initial baseline perfor-mance,so as to determine the cleaning efficiency by comparing the pure waterfluxes determined before fouling and after clean-ing.Throughout all the fouling/cleaning stages,the feed water in the reservoir,which was located on top of a magnetic stirrer,was mixed rigorously to ensure complete mixing of the feed water and cleaning solution.To confirm the reproducibility of determined cleaning effi-ciency,selected fouling/cleaning runs were duplicated.Results showed that fouling rate and cleaning efficiency obtained from the duplicate runs were within less than a5%difference.To investigate the change in the permeate quality during the fouling stage,permeate samples taken before and at the start and end of fouling were analyzed for salt(NaCl)rejection using an ICP-AES(ICP Optima3000,Perkin Elmer,Waltham,MA).Permeate and feed samplings obtained before the fouling run were collected at the end were collected during thefinal40min of the fouling run.2.6.AFM adhesion force measurementsAtomic force microscopy(AFM)was used to measure the inter-facial force between the foulant in the bulk solution and the foulant in the fouling layer on the membrane.The force measurements were performed with a colloid probe,modified from a commercial-ized SiN AFM probe(Veeco Metrology Group,Santa Barbara,CA).A carboxylate modified latex(CML)particle(Interfacial Dynam-ics Corp.,Portland,OR)was used as a surrogate for the organic foulants,because organic foulants(alginate and SRNOM)carry pre-dominantly carboxylic functional groups.To make a colloid probe, a CML particle with a diameter of4.0m was attached using Nor-land Optical adhesive(Norland Products,Inc.,Cranbury,NJ)to a tipless SiN cantilever.The colloid probe was cured under UV light for20min.The AFM adhesion force measurements were performed in a fluid cell using a closed inlet/outlet loop.The solution chemistries of the test solutions injected into thefluid cell were identical to those used in the bench-scale fouling/cleaning experiments.Once all the air bubbles had beenflushed out of thefluid cell,the injection would stop and the outlet was closed.The membrane was equilibrated with the test solution for30–45min before force measurements were performed.The force measurements were conducted at three tofive different locations,and at least10measurements were taken at each location.Because the focus of this study was on the foulant–foulant interaction(adhesion),only the raw data obtained from the retracting force curves were processed and converted to obtain the force versus surface-to-surface separation curves.The force curves presented were the averages of all the representative force curves obtained at the different locations.The protocol for AFM analysis has been modified slightly to investigate the interaction between different foulant types. The AFM colloidal probe is soaked in organic foulant solution (2000mg/L alginate,BSA,or SRNOM,or>98%octanoic acid)for at least24h(at4◦C for alginate,BSA,and SRNOM solutions to prevent organic degradation,and at room temperature for octanoic acid). The membrane is fouled with200mg/L organic foulant(alginate, BSA,SRNOM,or octanoic acid)using the crossflow unit for about 17h.After transferring the colloidal probe to the AFMfluid cell and the membrane to the AFM disc puck,an electrolyte solution con-taining0.5mM CaCl2and8.5mM NaCl(adjusted to pH6.5±0.2) (identical solution chemistry as during fouling)is injected into the fluid cell.The volume of electrolyte solution added is just enough tofill up thefluid cell so as to minimize the possibility offlush-ing away the foulants on the membrane and probe surfaces.AFM force measurements are taken after20min of equilibration time.To investigate the effect of cleaning agent on the intermolecular adhe-sion force,the cleaning agent was added to the electrolyte solution at the same concentration as that used in the cleaning experiments.2.7.Light scatteringDynamic light scattering experiments were performed on foulant solution to determine the effective hydrodynamic diam-eters of the foulant aggregates in foulant mixtures using a multi-detector light scattering unit(ALV-5000,Langen,Germany). New glass vials(Supelco,Bellefonte,PA)for containing foulant solu-tions under various solution chemistries were cleaned prior to use by soaking overnight in a cleaning solution(Extran MA01,Merck KGaA,Darmstadt,Germany),rinsing with DI water,and drying inW.S.Ang et al./Journal of Membrane Science376 (2011) 196–206199Fig.1.Influence of individual foulant type on fouling of LFC-1membranes:(a)in the absence of Ca2+and(b)in the presence of0.5mM Ca2+.The total ionic strength of the feed solution wasfixed at10mM by adjusting with NaCl and the feed solution pH was adjusted to6.0±0.2,as necessary,by adding NaOH.Fouling conditions: foulant concentration of25mg/L,initial permeateflux of23m/s(or83L m−2h−1), crossflow velocity of8.6cm/s,and temperature of21.0±0.5◦C.of1M NaOH.The vial containing the foulant solution was vortexed (Mini Vortexer,Fisher Scientific)to homogenize the solution.The vial was then allowed to sit for30min before starting the light scattering experiment.All light scattering measurements were conducted by employ-ing the detector positioned at a scattering angle of90◦from the incident laser beam.The detector signal was fed into the correla-tor,which accumulated each autocorrelation function for15s.The intensity-weighted hydrodynamic radius of the colloidal aggre-gates was determined with second-order cumulant analysis(ALV software)[27].The reported size is the average of thefirst20mea-surements.3.Results and discussion3.1.Membrane fouling3.1.1.Fouling with individual foulantsFig.1presents the normalizedflux profiles for LFC-1mem-branes fouled by each individual foulant(alginate,BSA,SRNOM, or octanoic acid)in the absence(Fig.1a)and presence(Fig.1b)of Ca2+,respectively.In the absence of Ca2+,theflux decline profiles of membranes fouled by the various foulants are insignificant.The 2+Fig.2.Influence of a mixture of(a)2foulants or(b)more than2foulants on fouling of LFC-1membranes in the presence of0.5mM Ca2+.The total ionic strength of the feed solution wasfixed at10mM by adjusting with NaCl and the feed solution pH was adjusted to6.0±0.2,as necessary,by adding NaOH.Fouling conditions were identical to those in Fig.1.RO membranes by BSA,SRNOM,or octanoic acid is minimal.How-ever,we have observed that the presence of Ca2+can affect fouling behavior when the foulant concentrations are higher(300mg/L BSA;2mM or288mg/L octanoic acid)[11,12].3.1.2.Fouling with mixture of foulantsTo investigate the implications for wastewater reclamation, the effect of Ca2+on fouling of RO membranes by all possible combinations of two or more foulant types is investigated.The con-centration of each foulant type was maintained at25mg/L.Fig.2a shows the normalizedflux profiles of membranes fouled by a mix-ture of two foulants in the presence of Ca2+.The effect of Ca2+is most significant for feed solutions containing alginate as one of the two foulant types.This mechanism will be further investigated with the aid of DLS and AFM paring theflux profiles of mem-branes fouled by alginate as a co-foulant,theflux-decline profile of membrane fouled by alginate and octanoic acid is the least sig-nificant due to the formation of octanoic acid–calcium complexes, which increase the hydrophilicity of the fouling layer[12].Fig.2b shows the normalizedflux profiles of membranes fouled by a mixture of three foulant types and all foulant types in the presence of Ca2+.In the presence of Ca2+,for membranes fouled by mixtures containing alginate,the effect of Ca2+onflux profiles is most significant,especially for the membrane fouled by a mixture of alginate,BSA,and SRNOM(without octanoic acid).In compar-ing the latter with theflux profile of the membrane fouled by all200W.S.Ang et al./Journal of Membrane Science376 (2011) 196–206Fig.3.Sodium ion(Na+)rejection of RO membranes measured before,and at the start and end of the fouling runs,at an adjusted feed solution pH of6.0.The membranes were fouled by combined foulant types,composed of25mg/L each of alginate,BSA,SRNOM,and octanoic acid.Permeate and feed samples obtained before the fouling run were collected30min before the onset of fouling.Samples taken at the start of the fouling run were initiated afterfirst discarding20mL of permeate(duration of8min).Permeate and feed samples taken at the end were collected during thefinal40min of the fouling run.Error bars indicate one standard deviation.Fouling conditions were identical to those in Fig.1.contained alginate and octanoic acid in the presence of Ca2+.The inhibitory effect of octanoic acid onflux-decline profiles can also be observed by comparing theflux profile of combined foulant types of alginate,SRNOM,and octanoic acid in Fig.2b with the profile of alginate and SRNOM in Fig.2a.3.1.3.Impact of fouling on salt rejectionFig.3presents Na+rejection of the RO membranes fouled by combined foulant types of alginate,BSA,SRNOM,and octanoic acid in the presence of Ca2+,at the start and end of the fouling runs.The trend of observed Na+rejection is similar both in the absence and presence of Ca2+.At the onset of fouling,the Na+rejection instan-taneously increases.This phenomenon is consistent with previous observations,which attributed the decrease in Na+permeability to the fouling layer acting as an additional selective barrier[12]. Toward the end of the fouling runs,the fouling layer becomes thicker and denser,resulting in even higher Na+rejection.It can be inferred that the presence of Ca2+resulted in a more compact fouling layer,which improves the ability of the fouling layer to fur-ther act as a selective barrier against the transport of Na+across the membrane.3.2.Fouling mechanisms3.2.1.Role of foulant–foulant interaction and foulant sizeRecent studies have demonstrated that the long-term organic fouling of RO membranes and the consequent behavior of water flux are dominated by the feed water chemistry and strong foulant–foulant interactions[4,20,21,28].Quantifying these inter-actions provides a basis for the understanding of the fouling mechanisms and for the rational selection of a suitable cleaning strategy.As discussed in Section3.1.2,fouling behavior becomes significant when alginate is one of the co-foulants.When alginate is absent from the feed solution,regardless of the other foulant types present,fouling is relatively insignificant.This behavior can be explained by evaluating the interaction forces among the differ-ent foulants.To investigate the effect of interactions of alginate with other foulant types,DLS analysis is performed on a solution contain-ing2foulant types(200mg/L alginate plus200mg/L of another foulant type)in the presence of Ca2+.Fig.4a shows that the alginate molecules in the solution have an effective hydrodynamic diame-ter of84nm,which is larger than the effective diameter of51nm of alginate molecules in a solution in which the foulant concentration is halved.The results imply that aggregation of alginate molecules is concentration dependent.The larger effective diameter of aggre-gates formed in400mg/L alginate solution as opposed to those formed in200mg/L alginate solution also implies a more exten-sive gel network at a higher concentration.The effective diameters of the foulant molecules in mixtures of alginate and BSA,alginate and SRNOM,and alginate and octanoic acid are,respectively,48, 63,and73nm.The effective diameter is an indirect indication of the foulant size due to aggregation between the foulants.Because of the varying interactions between alginate and another foulant type in the presence of Ca2+,the aggregate size differs for foulant aggregates of different foulant combinations.Fig.4b shows the intermolecular forces between foulant adsorbed on a colloidal probe and a membrane fouled by algi-nate as determined by AFM.For a membrane fouled by alginate and octanoic acid,the dominant foulant interactions are between alginate and alginate molecules(1.03mN/m)and between octanoic acid and octanoic acid molecules(0.90mN/m).For a membrane fouled by alginate and SRNOM,the dominant foulant interaction is between alginate and alginate molecules(1.03mN/m).For a membrane fouled by alginate and BSA,the dominant foulantinter-Fig.4.(a)Effective diameter of foulant aggregates in solutions of various foulant combinations that contain alginate as co-foulant.The foulant solution consists of200mg/L alginate plus200mg/L of another foulant type in an electrolyte solution of0.5mM CaCl2and8.5mM NaCl(same solution chemistry as that used in fouling experiments).TheW.S.Ang et al./Journal of Membrane Science376 (2011) 196–206201Fig.5.Proposed structure of fouling layer on membrane surface under different combinations of foulants.actions are between alginate and alginate molecules(1.03mN/m) and between alginate and BSA molecules(0.73–0.79mN/m).We observe that when alginate is present in the feed,regardless of the co-foulant,the interaction of alginate molecules among them-selves is most dominant,with the possibility of alginate molecules interacting with other molecules,especially BSA molecules.Comparing the effective diameters of the foulant aggregates in various2-foulant mixtures(Fig.4a)with the intermolecular adhe-sion force between different foulants(Fig.4b)reveals that there is an inverse correlation between the foulant aggregate size and the intermolecular adhesion force(foulant aggregate size generally decreases as intermolecular adhesion force increases).It is hypoth-esized that the interaction among the foulant types within the aggregates would affect the conformation,and hence,the size of the aggregates in the foulant solution.For example,the relatively stronger intermolecular adhesion force between alginate and BSA molecules in the feed solution in the presence of Ca2+results in a more‘compact’or‘tighter’conformation of the foulant aggregates as compared to the foulant aggregates formed from a solution of alginate and SRNOM.The deposition of the smaller and more‘com-pact’alginate–BSA aggregates results in a tighter fouling layer and a lowerfinalflux(Fig.5)[29].We note that the SA–SA aggregate does not follow the trend of a decrease in aggregate size with increasing adhesion force because alginate molecules tend to form extended gel networks in the presence of calcium ions[29],as opposed to the other combinations of foulants.3.2.2.Proposed structure of fouling layerThe fouling experiments reveal that membrane fouling in the presence of Ca2+is controlled by alginate.From the AFM force mea-surement analysis and the DLS experiments,the proposed structure of the fouling layer when severe fouling occurs under various solu-tion chemistries is schematically shown in Fig.5.The top drawing shows the likely conformation of the cross-linked alginate fouling layer when the feed contains alginate in the presence of Ca2+.In this case,the fouling layer has the typical structure resulting from the formation of an‘egg-box’shaped gel network on the mem-brane surface[29].The middle drawing shows the proposed fouling layer formed by a feed solution containing a mixture of alginate, BSA,SRNOM,and octanoic acid(each foulant has the same concen-tration).The DLS experiments show that the aggregates of foulant mixtures containing alginate as a co-foulant have smaller effective feed solution in which alginate is the sole foulant.When the algi-nate concentration is increased while maintaining the same total foulant concentration,the fouling layer becomes more porous due to the increase in the highly ordered alginate–calcium complexes on the membrane surface.The state of the fouling layer would affect the transfer of a cleaning agent to the fouling layer,and hence,the cleaning efficiency of the cleaning agent as delineated in the next sections.3.3.Cleaning of fouled membranes3.3.1.Type of cleaning agentFig.6presents the cleaning efficiencies of various cleaning agents on membranes fouled by combined foulant types compris-ing alginate,BSA,SRNOM,and octanoic acid in the presence of 0.5mM Ca2+.Cleaning was performed for15min without an oper-ating pressure(i.e.,no permeate)and at a crossflow velocityfive times higher than that during fouling.Cleaning the fouled mem-brane with DI water resulted in19%cleaning efficiency,which implies that the fouling layer on the membrane surface was largely irreversible.Conventional cleaning agents,such as NaOH(pH11),Fig.6.Cleaning efficiencies of various cleaning agents on membranes fouled by combined foulant types comprising alginate,BSA,SRNOM,and octanoic acid,with the concentration of each foulant type at25mg/L,in the presence of0.5mM Ca2+.Cleaning conditions:time,15min;temperature,21±0.5◦C;and no applied。
给排水专业汉英对照
AA/A/O法 anaerobic-anoxic-oxic process(厌氧-缺氧-好氧法)A/O法(厌氧-好氧法) anaerobic-oxic processA-A-O生物脱氮除磷工艺 A-A-O biological nitrogen and phosphorus removal processAB法 Adsorption Biodegradation process(吸附生物降解法)A-O除磷工艺 A-O phosphorus removal processA-O脱氮工艺 A-O nitrogen removal processBMTS型一体化氧化沟 BMTS intrachannel clarifier oxidation ditchBOD-污泥负荷 BOD-sludge loadK型叶轮曝气机 K type impeller aeratorLMPPhoredox nitrogen and phosphorus removal processr射线 gamma rayswater into groundwater aquifer氨氮 ammonia-nitrogen氨化反应 Nitragen氨基酸 amino acid铵盐 ammonium salt奥贝尔(Orbal)型氧化沟 Orbal oxidation ditch巴登福脱氮除磷工艺 Bardenpho nitrogen and phosphorus removal process白水(漂洗废水) white water(bleaching water)板框压滤 plate pressure filtration半渗透膜 semi-permeable membrane棒状杆菌属 corynebacterium薄膜式淋水材料 film packing 能使水流在填料表面形成连续薄水膜的淋水填料。
饱和常数(Ks) saturation constant饱和指数 saturation index,Langelier index 由理论推导公式得出一个指数，以定性地预测水中碳酸钙沉淀或暴雨公式 storm flow formula暴雨径流 storm runoff暴雨溢流井（截留井）storm overflow well, intercepting well 合流制排水系统中，用来截留、控制合流水量苯 benzene苯胺 aniline泵型叶轮暴气器 paddle impeller aerator泵站 pumping house 设置水泵机组、电气设备和管道、闸阀等的房屋。
给排水专业毕业论文中英文资料外文翻译文献
毕业论文外文资料翻译系别：环能学院专业：给水排水工程外文出处：Wan Fang foreign languagesliterature datebase附件：1、外文原文；2、外文资料翻译译文。
1、外文原文Supplying and draining waterin hospital construction With the fact that modern medicine science promptness develops,new technique , the new armamentarium are continuing without end , modernized medical treatment thereby consonant with that is building a hospital , are also are confronted with new design idea and new technology applying. Disregarding secondary hospital building function , what whose gets along environment, still , finclause the hospital builds equipment and is equipped with system, the request is without exception higher and higher. Because of it is to ensure daily work living not only need the rapid and intense life relevance recovering from the illness , avoiding crippling , rescuing, and promote with giving treatment to a patient. Not only the design accomplishing to the special field draining away water need to satisfy the request being unlike a function in hospital building on equipment , but also safety is be obliged to reliable. Following is built according to the hospital.一HOSPITAL GIVES A SEWERAGE1) Modernized hospital equipment and equipment system content is numerous , the function is peculiar , the request is very high. Except demanding to swear to continue supplying with the use water according with quality level sufficiently, need more according to demand of different medical treatment instrument and different administrative or tehcnical office to water quality , water pressure , the water temperature, classify setting up water treatment system and be in progress to system to increase pressure reduction.2) The hospital operating rooms , the delivery room operation the water hygiene, saliva washing hands by shower bath water , the dentistry dentistry chair ought to adopt the water purifying degassing. In the homeland few are large-scale , the high rank hospital centre supplies aroom, the centre disinfecting has also adopted to purify the water disinfecting, now that swear to there be no dust , the sterility , to remove the pathopoiesia source , to avoid the blockage infecting , cutting down equipment microtubule.3) Hospital preparation rooms preparation uses water to adopt distilled water, and sets up in making distilled water system to have part pressure boost facilities. The handicraft responds to according to different hospital preparation handicraft but fixes concrete system distilled water, should satisfy demand of whose handicraft to water quality , water yield , water pressure act in close coordination that the preparation handicraft reserves corresponding to drain-pipe and allocation chilled water circulatory system by the special field draining away water.4) Hospital operating rooms , delivery rooms , baby rooms , supply rooms , medical treatment of the dermatological department wards, door emergency call, cures skill every administrative or tehcnical office and the request difference that the staff and worker logistics branch supplies to hot water need to set up hot water respectively supplying system more. Ordinary circumstances door emergency call, cures skill administrative or tehcnical office , centre supply a room , the staff and worker logistics branch supplies hot water to water supply the regular time, the comparison supplying time is consistent. The hospital is based on major part at present financial resources, ward building hot water supplies basic to the regular time , ought to be that 24 hs supply hot water judging from long-term angle but. Operating room , the delivery room operation wash hands, the hygiene h by the fact that the shower bath ought to be 24 supplies hot water, moreover the block of wood5) Considers beautification to the environment , is inadvisable to adopt the steam boiled water stove , completely eradicates occurrence aroused the ward building pantry inner floor moistness , avoided interior wall mustiness phenomenon by leak or sparse steam water implement aerofluxus thereby. The hospital disregards size , boiled water supplies to should adopt automation volume or the electricity boiled water stove, a general disease area considers one , volume ascertains that according to using condition. The first easy to protect labor is managed, two is supplying ensuring that to the patient , improves the internal environment of ward at the same time.6)Especially infecting the section ward every door emergency call administrative or tehcnical office, every consulting room , the hand movement water curing a room , washing a basin should set up mistake chew , may adopt elbow style , knee style or dyadic switch of pedal. If using the dyadic switch of pedal to must use the product guarding against leakage, the floor is to avoid usinga place often damp , makes the patient , the medical personnel slip down , an accident happened. Operation waits for the operating room , the delivery room to wash hands should adopt the constant temperature muddy water valve , the constant temperature to produce water, taking as an example infrared ray induced electromagnetic valve control mode for fine. Cure skill part control laboratory , laboratory of administrative or tehcnical office have the peculiar request , water chews the form should ascertain whose water according to every administrative or tehcnical office coming functional request chewing.7)Many administrative or tehcnical office, especially downstream pipelines such as pickling bath , the pool disinfecting , develop pool in administrative or tehcnical office such as checking the room , the control laboratory , emitting section responds to of hospitals are adopt to be able to bear the rotten PVC2U draining off silent stock tube.8) Pair of filth , waste water of all kinds must classify strictly according to the country in connection with the effluent standard , the field carrying out a pertinency with different treatment handicraft deals with and handles.9) Uses a function to need since the modern hospital needs to be satisfied with not only , wants to think that the interior outside environment is beautiful too at the same time. The building needs especially door emergency call, cures skill sometimes because of medical treatment function , give the horizontal stroke draining away water , erect a tube arrange to lie scattered comparatively, more bright dew is in interior, warm the pipeline exchanging special field up in addition sometimes , make the pipeline that the room inner clearly shows more than the correct or required number , both inelegant, and affect hygiene. This demands right away in the process of engineering design , the rational arrangement the structure form should fully utilize not being the same as is carried out, needs to make the various pipeline conceal arrangement to the full according to the function , pays attention to beautiful befitting one's position or suited to the occasion under not affecting the premise being put into use. Certainly, these require that building structure special field is dense. Tier of furred ceilings and the basement top sometimes are every special field pipeline aggregation field , every special field norm and request having every special field , each sometimes arranges if the building designs middle in the ward,whose result either increase building storey height, or cannot attend to one thing without neglecting another. For overcoming this one abuse, should think in general that bigger flue pipe arrangement be in the most superjacent, it's on the down part is that several special field arrangement props up the publicspace being in charge of , down part is to arrange to give draining off , driving force , strong , weak electricity every system to do a tube again. Such is arranged than form arrangement is other comparatively economical , pragmatic.10) Exchangers forms choice. In the system the tradition hospital hot water is supplied, people adopt volume mainly dyadic exchanger. Have been to think that what be provided steam amounts and hot water supplies the adjustment amounts dispatching value between maximum value mainly , have diminished a steam boiler designing amounts , have decreased by boiler room Zhan field area , have saved one time investment. People demands but more highly, and more highly, especially the example discovering army group bacterium pathopoiesia in life hot water to water quality now , the altitude arousing people takes seriously. Be a bacterium mainly because of in the water 55 ~C is the easiest to breed an army group in 30 ~C ~, WHO (WHO) is recommended by for this purpose: "Hot water responds to in 60 ~C use And cycle at least above 50 ~C. Come if some users, need to fall to 40 ~C or 50 ~C or so with the faucet water temperature, to come true being able to use a thermoregulation to blend a valve at this time. The growth being a temperature Bu Li Yu pneumonia diplococcus swear to store water, is a regulating valve's turn to should set up the place closing down and suspending operation of point in drawing near". This be especially important to the hospital. Because of being in hospital the weak having disease,if bacterium of army group happened within the hospital is to be harmful for patient to treat and recover from the illness,the hospital has a grave responsibility. At present small hospital within the hospital especially a little condition is relatively poor , include the part area level hospital, 24 unable hs supply hot water, and volume the dyadic converter inner water temperature is to use echelon in inside of exchanger, the water temperature very difficult to make keeps in 60 ~C or so. Thereby, lead to volume produce the bacterium of army group in the pipeline supplying hot water system within dyadic exchanger , change a hospital using the exchanger form to respond to be a task of top priority. Adopt half to be to heat up style or be a dyadic hot exchanger , make whose hot water supply the system water temperature keeping the water supply being in progress in all above 60 ~C area all the time, occurrence propagating , completely eradicating the bacterium of army group in order to avoiding the bacterium of army group.二MULTILAYER WATER SUPPL Y SYSTEMAt present, great majority cities municipal administration pipe network pressure can maintain above 2 kilograms in the homeland , take place individual small town water pressure can reach 4kilograms even. The pressure therefore, building the municipal administration pipe network's to the same multilayer has been already sufficient , has been in a small town especially since but municipal administration pipe network water yield supplying water , water pressure fluctuation are bigger. Have several kinds the following types mainly for overcome these shortcomings , multilayer water supply system design.1) Direct water supply type is that pressure , direct water supply , sort making use of municipal administration pipe network directly apply to slightly high area of municipal administration pipe network pressure or higher range of water works vicinity pressure inner. The shortcoming it is water yield , water pressure to be able to not ensure that. This water supply scheme economy function is very good but, to less pipe network of scale , does not need any other equipment or measure.2) Water box water supply types have led municipal administration pipe network water to roof water box , discrepancy in elevation , gravity depending on a water box and using the water appliance have supplied water , have overcome water pressure water yield block of wood stability and then. Since but, secondary pollution, moreover, water box volume that the water box there exists in possibility is bigger,this way does not encourage therefore.3) Water boxes , pipe networks ally self with a type when the ordinary time water yield water pressure is sufficient , unnecessary water enters the roof water box when covering water supply , overpressure as with a net directly from municipal administration, think that the water box supplies water to the consumer by gravity automation when pressure or the water yield is insufficient. The main force who is that regular directness supplies water on physics structure stretches the top cut-over water box , sets up and one exhalent siphon from the water box. Owe a scheme the volume having diminished a water box, and make water not need to enter a water box staying this one step , hygiene reliability increase by. The problem is (that the municipal administration now pipe network can accomplish) but if longtime stabilivolt supplies water , the water sojourn time in water box is on the contrary greatly increase by , easier to be contaminated. And, the water box all must readjust oneself to a certain extent in the building in all usage water boxes system most higher place, attractive looks being able to affect a building in some occasion , the physical design building even.4) Pressure jars supply water since insecure water box factor , reason why use the jar sealing off reliable pressure to replace, and the pressure jar does not need, high position lay down,attractive looks and structure not affecting a building bearing , go down well very much over the past few years. Pressure jar system requires that the water pump and autocontrol system have to fit but , feasible cost increases by to some extent. However, in the late years whose market price already lets many consumers be able to choose.Systematic pressure jar principle is to make use of a water pump water compression to be sent to receive the pipe network building the inside , thinks that water enters the pressure jar , reaches certain pressure time , water pump motor stoppage or reduces the speed when pressure is too big,While pressure is smaller than regulation value, the pressure jar conveys water to the outside and starts the water pump or acceleration at the same time (frequency conversion water pump).5) Two time of compression types can make do for to small-scale consumer ,if the building , the pressure jar are only systematic. The direction that the dwelling house spends at present to housing estate develops but, shows for the cluster arrangement that multilayer builds , concentrates stabilivolt mainly. The ability can not satisfy a request with pressure jar volume , the water pump concentrates compression therefore having appeared give first place to, pressure jar stabilivolt (remove the system water hammer) is subsidiary way. Economy cost rises only , also needs the specially-assigned person upkeep. Besides, pipe network system belongs to low pressure since tier of numbers are not many, pipeline, the direct cut-over without exception with layers consumer is be OK , comparatively simple. The steel tube prepares pipeline material with low pressure low pressure PPR silent stock tube give first place to.2、外文资料翻译译文医院建筑给水排水随着现代医学科学的迅速发展,新技术、新医疗设备层出不穷,从而与之相符的现代化医疗建筑———医院,也面临着新的设计理念和新技术的运用。
建筑给排水 外文文献翻译1
本科毕业设计外文文献及译文文献、资料题目：Sealed building drainageand vent systems文献、资料来源：国道数据库文献、资料发表（出版）日期：2005.9.12院（部）：市政与环境工程学院专业：给水排水工程班级：姓名：学号：指导教师：翻译日期： 2012.06外文文献：Sealed building drainage and vent systems—an application of active air pressure transient control and suppression AbstractThe introduction of sealed building drainage and vent systems is considered a viable proposition for complex buildings due to the use of active pressure transient control and suppression in the form of air admittance valves and positive air pressure attenuators coupled with the interconnection of the network's vertical stacks.This paper presents a simulation based on a four-stack network that illustrates flow mechanisms within the pipework following both appliance discharge generated, and sewer imposed, transients. This simulation identifies the role of the active air pressure control devices in maintaining system pressures at levels that do not deplete trap seals.Further simulation exercises would be necessary to provide proof of concept, and it would be advantageous to parallel these with laboratory, and possibly site, trials for validation purposes. Despite this caution the initial results are highly encouraging and are sufficient to confirm the potential to provide definite benefits in terms of enhanced system security as well as increased reliability and reduced installation and material costs.Keywords: Active control; Trap retention; Transient propagationNomenclatureC+-——characteristic equationsc——wave speed, m/sD——branch or stack diameter, mf——friction factor, UK definition via Darcy Δh=4fLu2/2Dgg——acceleration due to gravity, m/s2K——loss coefficientL——pipe length, mp——air pressure, N/m2t——time, su——mean air velocity, m/sx——distance, mγ——ratio specific heatsΔh——head loss, mΔp——pressure difference, N/m2Δt——time step, sΔx——internodal length, mρ——density, kg/m3Article OutlineNomenclature1. Introduction—air pressure transient control and suppression2. Mathematical basis for the simulation of transient propagation in multi-stack building drainage networks3. Role of diversity in system operation4. Simulation of the operation of a multi-stack sealed building drainage and vent system5. Simulation sign conventions6. Water discharge to the network7. Surcharge at base of stack 18. Sewer imposed transients9. Trap seal oscillation and retention10. Conclusion—viability of a sealed building drainage and vent system1.Air pressure transients generated within building drainage and vent systems as a natural consequence of system operation may be responsible for trap seal depletion and cross contamination of habitable space [1]. Traditional modes of trap seal protection, based on the Victorian engineer's obsession with odour exclusion [2], [3] and [4], depend predominantly on passive solutions where reliance is placed on cross connections and vertical stacks vented to atmosphere [5] and [6]. This approach, while both proven and traditional, has inherent weaknesses, including the remoteness of the vent terminations [7], leading to delays in the arrival of relieving reflections, and the multiplicity of open roof level stack terminations inherent within complex buildings. The complexity of the vent system required also has significant cost and space implications [8].The development of air admittance valves (AAVs) over the past two decades provides the designer with a means of alleviating negative transients generated as random appliance discharges contribute to the time dependent water-flow conditions within the system. AAVs represent an active control solution as they respond directly to the local pressure conditions, opening as pressurefalls to allow a relief air inflow and hence limit the pressure excursions experienced by the appliance trap seal [9].However, AAVs do not address the problems of positive air pressure transient propagation within building drainage and vent systems as a result of intermittent closure of the free airpath through the network or the arrival of positive transients generated remotely within the sewer system, possibly by some surcharge event downstream—including heavy rainfall in combined sewer applications.The development of variable volume containment attenuators [10] that are designed to absorb airflow driven by positive air pressure transients completes the necessary device provision to allow active air pressure transient control and suppression to be introduced into the design of building drainage and vent systems, for both ‘standard’ buildings and those requiring particular attention to be paid to the security implications of multiple roof level open stack terminations. The positive air pressure attenuator (PAPA) consists of a variable volume bag that expands under the influence of a positive transient and therefore allows system airflows to attenuate gradually, therefore reducing the level of positive transients generated. Together with the use of AAVs the introduction of the PAPA device allows consideration of a fully sealed building drainage and vent system.Fig. 1illustrates both AAV and PAPA devices, note that the waterless sheath trap acts as an AA V under negative line pressure.Fig. 1. Active air pressure transient suppression devices to control both positive and negative surges.Active air pressure transient suppression and control therefore allows for localized intervention to protect trap seals from both positive and negative pressure excursions. This hasdistinct advantages over the traditional passive approach. The time delay inherent in awaiting the return of a relieving reflection from a vent open to atmosphere is removed and the effect of the transient on all the other system traps passed during its propagation is avoided.2.Mathematical basis for the simulation of transient propagation in multi-stack building drainage networks.The propagation of air pressure transients within building drainage and vent systems belongs to a well understood family of unsteady flow conditions defined by the St Venant equations of continuity and momentum, and solvable via a finite difference scheme utilizing the method of characteristics technique. Air pressure transient generation and propagation within the system as a result of air entrainment by the falling annular water in the system vertical stacks and the reflection and transmission of these transients at the system boundaries, including open terminations, connections to the sewer, appliance trap seals and both AAV and PAPA active control devices, may be simulated with proven accuracy. The simulation [11] provides local air pressure, velocity and wave speed information throughout a network at time and distance intervals as short as 0.001 s and 300 mm. In addition, the simulation replicates local appliance trap seal oscillations and the operation of active control devices, thereby yielding data on network airflows and identifying system failures and consequences. While the simulation has been extensively validated [10], its use to independently confirm the mechanism of SARS virus spread within the Amoy Gardens outbreak in 2003 has provided further confidence in its predictions [12].Air pressure transient propagation depends upon the rate of change of the system conditions. Increasing annular downflow generates an enhanced entrained airflow and lowers the system pressure. Retarding the entrained airflow generates positive transients. External events may also propagate both positive and negative transients into the network.The annular water flow in the ‘wet’ stack entrains an airflow due to the condition of ‘no slip’ established between the annular water and air core surfaces and generates the expected pressure variation down a vertical stack. Pressure falls from atmospheric above the stack entry due to friction and the effects of drawing air through the water curtains formed at discharging branch junctions. In the lower wet stack the pressure recovers to above atmospheric due to the traction forces exerted on the airflow prior to falling across the water curtain at the stack base.The application of the method of characteristics to the modelling of unsteady flows was first recognized in the 1960s [13]. The relationships defined by Jack [14] allows the simulation to model the traction force exerted on the entrained air. Extensive experimental data allowed the definition of a ‘pseudo-friction factor’ applicable in the wet stack and operable across the water annular flow/entrained air core interface to allow combined discharge flows and their effect on airentrainment to be modelled.The propagation of air pressure transients in building drainage and vent systems is defined by the St Venant equations of continuity and momentum [9],(1)(2)These quasi-linear hyperbolic partial differential equations are amenable to finite difference solution once transformed via the Method of Characteristics into finite difference relationships, Eqs. (3)–(6), that link conditions at a node one time step in the future to current conditions at adjacent upstream and downstream nodes, Fig. 2.Fig.2. St Venant equations of continuity and momentum allow airflow velocity and wave speed to bepredicted on an x-t grid as shown. Note , .For the C+ characteristic:(3)when(4)and the C- characteristic:(5)when(6)where the wave speed c is given byc=(γp/ρ)0.5. (7) These equations involve the air mean flow velocity, u, and the local wave speed, c, due to the interdependence of air pressure and density. Local pressure is calculated as(8)Suitable equations link local pressure to airflow or to the interface oscillation of trap seals.The case of the appliance trap seal is of particular importance. The trap seal water column oscillates under the action of the applied pressure differential between the transients in the network and the room air pressure. The equation of motion for the U-bend trap seal water column may be written at any time as(9)It should be recognized that while the water column may rise on the appliance side, conversely on the system side it can never exceed a datum level drawn at the branch connection.In practical terms trap seals are set at 75 or 50 mm in the UK and other international standards dependent upon appliance type. Trap seal retention is therefore defined as a depth less than the initial value. Many standards, recognizing the transient nature of trap seal depletion and the opportunity that exists for re-charge on appliance discharge allow 25% depletion.The boundary equation may also be determined by local conditions: the AAV opening and subsequent loss coefficient depends on the local line pressure prediction.Empirical data identifies the AAV opening pressure, its loss coefficient during opening and at the fully open condition. Appliance trap seal oscillation is treated as a boundary condition dependent on local pressure. Deflection of the trap seal to allow an airpath to,or from, the appliance or displacement leading to oscillation alone may both be modelled. Reductions in trap seal water mass during the transient interaction must also be included.3. Role of diversity in system operationIn complex building drainage networks the operation of the system appliances to discharge water to the network, and hence provide the conditions necessary for air entrainment and pressure transient propagation, is entirely random. No two systems will be identical in terms of their usage at any time. This diversity of operation implies that inter-stack venting paths will be established if the individual stacks within a complex building network are themselves interco nnected. It is proposed that this diversity is utilized to provide venting and to allow serious consideration to be given to sealed drainage systems.In order to fully implement a sealed building drainage and vent system it would be necessary for the negative transients to be alleviated by drawing air into the network from a secure space andnot from the external atmosphere. This may be achieved by the use of air admittance valves or at a predetermined location within the building, for example an accessible loft space.Similarly, it would be necessary to attenuate positive air pressure transients by means of PAPA devices. Initially it might be considered that this would be problematic as positive pressure could build within the PAPA installations and therefore negate their ability to absorb transient airflows. This may again be avoided by linking the vertical stacks in a complex building and utilizing the diversity of use inherent in building drainage systems as this will ensure that PAPA pressures are themselves alleviated by allowing trapped air to vent through the interconnected stacks to the sewer network.Diversity also protects the proposed sealed system from sewer driven overpressure and positive transients. A complex building will be interconnected to the main sewer network via a number of connecting smaller bore drains. Adverse pressure conditions will be distributed and the network interconnection will continue to provide venting routes.These concepts will be demonstrated by a multi-stack network.4. Simulation of the operation of a multi-stack sealed building drainage and vent systemFig. 3 illustrates a four-stack network. The four stacks are linked at high level by a manifold leading to a PAPA and AAV installation. Water downflows in any stack generate negative transients that deflate the PAPA and open the AAV to provide an airflow into the network and out to the sewer system. Positive pressure generated by either stack surcharge or sewer transients are attenuated by the PAPA and by the diversity of use that allows one stack-to-sewer route to act as a relief route for the other stacks.The network illustrated has an overall height of 12m. Pressure transients generated within thenetwork will propagate at the acoustic velocity in air . This implies pipe periods, from stack base to PAPA of approximately 0.08s and from stack base to stack base of approximately 0.15s.In order to simplify the output from the simulation no local trap seal protection is included—for example the traps could be fitted with either or both an AAV and PAPA as examples of active control. Traditional networks would of course include passive venting where separate vent stacks would be provided to atmosphere, however a sealed building would dispense with this venting arrangement.Fig.3.Four stack building drainage and vent system to demonstrate the viability of a sealed building system.Ideally the four sewer connections shown should be to separate collection drains so that diversity in the sewer network also acts to aid system self venting. In a complex building this requirement would not be arduous and would in all probability be the norm. It is envisagedthat the stack connections to the sewer network would be distributed and would be to a below ground drainage network that increased in diameter downstream. Other connections to the network would in all probability be from buildings that included the more traditional open vent system design so that a further level of diversity is added to offset any downstream sewer surcharge events of long duration. Similar considerations led to the current design guidance for dwellings.It is stressed that the network illustrated is representative of complex building drainage networks. The simulation will allow a range of appliance discharge and sewer imposed transient conditions to be investigated.The following appliance discharges and imposed sewer transients are considered:1. w.c. discharge to stacks 1–3 over a period 1–6s and a separate w.c. discharge to stack 4 between 2 and 7s.2. A minimum water flow in each stack continues throughout the simulation, set at 0.1L/s, to represent trailing water following earlier multiple appliance discharges.3. A 1s duration stack base surcharge event is assumed to occur in stack 1 at 2.5s.4. Sequential sewer transients imposed at the base of each stack in turn for 1.5s from 12 to 18s.The simulation will demonstrate the efficacy of both the concept of active surge control and inter-stack venting in enabling the system to be sealed, i.e. to have no high level roof penetrations and no vent stacks open to atmosphere outside the building envelope.The imposed water flows within the network are based on ‘real’ system values, being representative of current w.c. discharge characteristics in terms of peak flow, 2l/s, overall volume, 6l, and duration, 6s. The sewer transients at 30mm water gauge are representative but not excessive. Table 1 defines the w.c. discharge and sewer pressure profiles assumed.Table1. w.c. discharge and imposed sewer pressure characteristicsw.c. discharge characteristic Imposed sewer transient at stack baseTime Discharge flow Time PressureSeconds l/s Seconds Water gauge (mm)Start time 0.0 Start time 0.0+2 2.0 +0.5 30.0+4 2.0 +0.5 30.0+6 0.0 +0.5 0.05. Simulation conventionsIt should be noted that heights for the system stacks are measured positive upwards from the stack base in each case. This implies that entrained airflow towards the stack base is negative. Airflow entering the network from any AAVs installed will therefore be indicated as negative. Airflow exiting the network to the sewer connection will be negative.Airflow entering the network from the sewer connection or induced to flow up any stack will be positive.Water downflow in a vertical is however regarded as positive.Observing these conventions will allow the following simulation to be better understood.6. Water discharge to the networkTable 1 illustrates the w.c. discharges described above, simultaneous from 1s to stacks 1–3 and from 2s to stack 4. A base of stack surcharge is assumed in stack 1 from 2.5 to 3s. As a result it will be seen from Fig. 4 that entrained air downflows are established in pipes 1, 6 and 14 asexpected. However, the entrained airflow in pipe 19 is into the network from the sewer. Initially, as there is only a trickle water flow in pipe 19, the entrained airflow in pipe 19 due to the w.c. discharges already being carried by pipes 1, 6 and 14, is reversed, i.e. up the stack, and contributes to the entrained airflow demand in pipes 1, 6 and 14. The AAV on pipe 12 also contributes but initially this is a small proportion of the required airflow and the AAV flutters in response to local pressure conditions.Fig.4.Entrained airflows during appliance discharge.Following the w.c. discharge to stack 4 that establishes a water downflow in pipe 19 from 2 s onwards, the reversed airflow initially established diminishes due to the traction applied by the falling water film in that pipe. However, the suction pressures developed in the other three stacks still results in a continuing but reduced reversed airflow in pipe 19. As the water downflow in pipe 19 reaches its maximum value from 3 s onwards, the AAV on pipe 12 opens fully and an increased airflow from this source may be identified. The flutter stage is replaced by a fully open period from 3.5 to 5.5 s.Fig. 5 illustrates the air pressure profile from the stack base in both stacks 1 and 4 at 2.5 s into the simulation. The air pressure in stack 4 demonstrates a pressure gradient compatible with the reversed airflow mentioned above. The air pressure profile in stack 1 is typical for a stack carrying an annular water downflow and demonstrates the establishment of a positive backpressure due to the water curtain at the base of the stack.Fig.5.Air pressure profile in stacks 1 and 4 illustrating the pressure gradient driving the reversed airflow in pipe 19.The initial collapsed volume of the PAPA installed on pipe 13 was 0.4l, with a fully expanded volume of 40l, however due to its small initial volume it may be regarded as collapsed during this phase of the simulation.7. Surcharge at base of stack 1Fig. 6 indicates a surcharge at the base of stack 1, pipe 1 from 2.5 to 3 s. The entrained airflow in pipe 1 reduces to zero at the stack base and a pressure transient is generated within that stack, Fig.6. The impact of this transient will also be seen later in a discussion of the trap seal responses for the network.Fig.6.Air pressure levels within the network during the w.c. discharge phase of the simulation. Note surcharge at base stack 1, pipe 1 at 2.5s.It will also be seen, Fig. 6, that the predicted pressure at the base of pipes 1, 6 and 14, in the absence of surcharge, conform to that normally expected, namely a small positive back pressure as the entrained air is forced through the water curtain at the base of the stack and into the sewer. In the case of stack 4, pipe 19, the reversed airflow drawn into the stack demonstrates a pressure drop as it traverses the water curtain present at that stack base.The simulation allows the air pressure profiles up stack 1 to be modelled during,and following, the surcharge illustrated in Fig. 6. Fig. 7(a) and (b) illustrate the air pressure profiles in the stack from 2.0 to 3.0 s, the increasing and decreasing phases of the transient propagation being presented sequentially. The traces illustrate the propagation of the positive transient up the stack as well as the pressure oscillations derived from the reflection of the transient at the stack termination at the AAV/PAPA junction at the upper end of pipe 11.Fig.7.(a) Sequential air pressure profiles in stack 1 during initial phase of stack base surcharge. (b) Sequential air pressure profiles in stack 1 during final phase of stack base surcharge.8. Sewer imposed transientsTable 2 illustrates the imposition of a series of sequential sewer transients at the base of eachstack. Fig. 8 demonstrates a pattern that indicates the operation of both the PAPA installed on pipe 13 and the self-venting provided by stack interconnection.Fig.8.Entraind airflows as a result of sewer imposed pressure transients.As the positive pressure is imposed at the base of pipe 1 at 12 s, airflow is driven up stack 1 towards the PAPA connection. However, as the base of the other stacks have not a yet had positive sewer pressure levels imposed, a secondary airflow path is established downwards to the sewer connection in each of stacks 2–4, as shown by the negative airflows in Fig. 8.As the imposed transient abates so the reversed flow reduces and the PAPA discharges air to the network, again demonstrated by the simulation, Fig. 8. This pattern repeats as each of the stacks is subjected to a sewer transient.Fig. 9 illustrates typical air pressure profiles in stacks 1 and 2. The pressure gradient in stack 2 confirms the airflow direction up the stack towards the AAV/PAPA junction. It will be seen that pressure continues to decrease down stack 1 until it recovers, pipes 1 and 3, due to the effect of the continuing waterflow in those pipes.The PAPA installation reacts to the sewer transients by absorbing airflow, Fig. 10. The PAPA will expand until the accumulated air inflow reaches its assumed 40 l volume. At that point the PAPA will pressurize and will assist the airflow out of the network via the stacks unaffected by the imposed positive sewer transient. Note that as the sewer transient is applied sequentially from stacks 1–4 this pattern is repeated. The volume of the high level PAPA, together with any others introduced into a more complex network, could be adapted to ensure that no system pressurization occurred.Fig.9.Air pressure profile in stack 1 and 2 during the sewer imposed transient in stack 2, 15s into the simulation.Fig.10.PAPA volume and AAV throughflow during simulation.The effect of sequential transients at each of the stacks is identifiable as the PAPA volume decreases between transients due to the entrained airflow maintained by the resid ual water flows in each stack.9. Trap seal oscillation and retentionThe appliance traps connected to the network monitor and respond to the local branch air pressures. The model provides a simulation of trap seal deflection, as well as final retention. Fig. 11(a,b) present the trap seal oscillations for one trap on each of the stacks 1 and 2, respectively. As the air pressure falls in the network, the water column in the trap is displaced so that the appliance side water level falls. However, the system side level is governed by the level of the branch entry connection so that water is lost to the network. This effect is illustrated in both Fig. 11(a) and (b).Transient conditions in the network result in trap seal oscillation, however at the end of the event the trap seal will have lost water that can only be replenished by the next appliance usage. If the transient effects are severe than the trap may become totally depleted allowing a potential cross contamination route from the network to habitable space. Fig. 11(a) and (b) illustrate the trap seal retention at the end of the imposed network transients.Fig.11.(a) Trap seal oscillation, trap 2. (b) Trap seal oscillation, trap 7.Fig. 11(a), representing the trap on pipe 2, illustrates the expected induced siphonage of trap seal water into the network as the stack pressure falls. The surcharge event in stack 1 interrupts this process at 2s. The trap oscillations abate following the cessation of water downflow in stack 1. The imposition of a sewer transient is apparent at 12s by the water surface level rising in the appliance side of the trap. A more severe transient could have resulted in ‘bubbling through’ at this stage if the trap system side water surface level fell to the lowest point of the U-bend.The trap seal oscillations for traps on pipes 7, Fig. 11(b) and 15, are identical to each other until the sequential imposition of sewer transients at 14 and 16s. Note that thesurcharge in pipe 1 does not affect these traps as they are remote from the base of stack 1. The trap on pipe 20 displays an initial reduction in pressure due to the delay in applied water downflow. The sewer transient in pipe 19 affects this trap at around 18s.As a result of the pressure transients arriving at each trap during the simulation there will be a loss of trap seal water. This overall effect results in each trap displaying an individual water seal retention that depends entirely on the usage of the network. Trap 2 retains 32mm water seal while traps 7 and 15 retain 33mm. Trap 20 is reduced to 26mm water seal. Note that the traps on pipes 7 and 15 were exposed to the same levels of transient pressure despite the time difference in arrival of the sewer transients. Fig. 11(a) and (b) illustrate the oscillations of the trap seal column as a result of the solution of the trap seal boundary condition, Eq. (10), with the appropriate C+ characteristic. This boundary condition solution continually monitors the water loss from the trap and at the end of the event yields a trap seal retention value. In the example illustrated the initial trap seal values were taken as 50mm of water, common for appliances such as w.c.'s and sinks.10. Conclusion—viability of a sealed building drainage and vent systemThe simulation presented confirms that a sealed building drainage system utilizing active transient control would be a viable design option. A sealed building drainage system would offer the following advantages:• System security would be immeasurably enhanced as all high-level open system terminations would be redundant.• System complexity would be reduced while system predictability would increase.• Space and material savings would be achieved within the construction phase of any installation.These benefits would be realized provided that active transient control and suppression was incorporated into the design in the form of both AAV to suppress negative transients and variable volume containment devices (PAPA) to control positive transients.The diversity inherent in the operation of both building drainage and vent systems and the sewers connected to the building have a role in providing interconnected relief paths as part of the system solution.The method of characteristics based finite difference simulation presented has provided output consistent with expectations for the operation of the sealed system studied. The accuracy of the simulation in other recent applications, including the accurate corroboration of the SARS spread mechanism within the Amoy Gardens complex in Hong Kong in 2003, pro vides a confidence level in the results presented.。
英文文献 给排水专业
Research on Facilitation of Biodegradation for Azo Dye Wastewater by Bioelectrochemical TechnologyZHAO Yuhua，CANG Xiaoyi, JIN Decai, DONG RuijiaoSchool of Municipal and Environment Engineering Shenyang Jianzhu University Shenyang，China 110168 zyh088@, 666xiaoyi@,kingdecai123@, dongruijiao@Abstract—Active brilliant red X-3B is a kind of azo dye which is difficult to biodegrade. The wastewater with azo dye is of chromaticity depth, high content of organic compounds, water quality changing great, and seriously impacts environment. Bioelectrochemical hydrolysis coupled with biological contact oxidation (BEH-BCO) was used to treat azo dye active brilliant red X-3B simulation wastewater. In this experiment, synergy of micro-electrolysis and biological hydrolysis was used to improve the efficiency of hydrolysis reactor, and then improve the biodegradation of azo dye wastewater. In the experiment, the HRT of Hydrolysis reactor kept running 12h, and the HRT of biological contact oxidation reactor 7.95h. The electric current densities used in the experiment were 0.024, 0.048, 0.071mA/cm2. This experiment was compared with the biological hydrolysis and biological contact oxidation (BH-BCO), the single biological treatment. Experiment results showed that, the removal effect of active brilliant red X-3B by bioelectrochemical technology was very good in heavy dye mass concentration in raw water (concentration was 50mg/L); and in the range of current density used in test, the treatment effect was increased with the increase of electric current density; when electric current density was 0.071mA/cm2, the average removal ratio of dye mass concentration, colority, CODCr, and NH3-N reached 98.77%, 91.39%, 69.98%, and 90.41% by bioelectrochemical technology respectively, and 9.65%, 18.21%, 31.32%, and 85.69% respectively by the single biological method. There are some reasons for the results. The first reason is that the dye mass concentration of wastewater in raw water was too high, single biological hydrolysis was difficult [1]. The second reason is that, from the measure results of oxidation reduction potential, the hydrolysis reactor was in anaerobic condition in the experimental process, which produced inhibitory environment to bacteria. The analysis of UV-visible absorption spectrum of the influent and effluent from each reactor indicated that the molecular structure of active brilliant red X-3B was destroyed by bioelectrochemical technology and turned into readily biodegradable small molecular organic compound, but it changed little by biological treatment. The measure results of redox potential showed that, the redox potential of mixed liquor in BEH was about -200mV, which is within the range of azo compound redox required standards (-180mV ～ -430mV); the redox potential of mixed liquor in BH was about -152mV, which is not in the required range, and is also not in the range of hydrolysis reactor working normally (about 0mV). The results of measured azoreductase activity show that the azoreductase activity of the single biological hydrolysis was 1.68 mg/L·h, the azoreductase activity of bioelectrochemical hydrolysis was 55.33 mg/L·h. In a word, bioelectrochemical technology could promote the activity of hydrolysis microbe greatly, and obviously improve the decolorization effect of active brilliant red X-3B wastwater. It plays a great role in promoting biodegradation of azo dye wastewater. Keywords-azo dye wastewater; bioelectrochemical; hydrolysis; contact oxidation; active brilliant red X-3BI.INTRODUCTIONAzo dye is widely used in the trades of printing, food, cosmetics, and so on [2]. Azo dye wastewater with huge volume and extensive distribution, changing water quality greatly, high concentration of toxic organic compounds, heavy colority, and complicated biodegradation, is one of the intractable industrial wastewaters. The routine methods to treat dye wastewater include physical method, chemical method, biological method, electrochemical method, and etc. These methods exist obviously disadvantages when they are used [3]. Bioelectrochemical technology is a method that electrochemical reaction and biochemical reaction are set off in a same reactor. It could make electrochemical reaction and microbial reaction complementary and enhance each other, and improve the efficiency of treating wastewater, and reduce the equipment initial investment [4]. In this test, bioelectrochemical technology was applied to treat active brilliant red X-3B that is in a simulated dye wastewater, researched the strengthening effect of bioelectrochemical technology by the contrast experiments between BEH-BCO process and BH-BCO process, and explored the biodegradation mechanism of active brilliant red X-3B. II. TESTER, MATERIALS AND METHODS A. Tester and methods The schematic of the experiment system was showed in Fig.1. This experiment system was divided into two parts, A and B. Part A was BEH-BCO process. In this process, iron sheet (100cm×50cm) in hydrolysis reactor is as the anode, and graphite column (diameter 4cm, high 100cm) as the cathode. Part B was BH-BCO process.This project is supported by Municipal & Environmental Engineering Key Laboratory Open Foundation of Colleges and Universities in Liaoning Province (No.SZ-200901) and Science and Technology Foundation of Ministry of Housing and Urban-Rural Development (No.2010-K7-14).At the bottom of hydrolysis reactor, pulse current which is provided by air compressor play a part in stir mainly, and shall not exceed the limit of dissolved oxygen (DO) in hydrolysis reactor. Continuous aeration was offered to the contact oxidation reactor. Insides of hydrolysis reactor and contact oxidation reactor placed the combination filling (specific surface area 1400-2500 m2/m3). Both BEH-BCO process and BH-BCO process had the same design parameters. Effective volume of BEH reactor was 24L. The hydraulic residence time of BEH was 12h. Useful volume of BCO reactor was 15.9L. The hydraulic residence time was 7.95h. Flow rate was 2L/h. Because the hydrolysis reactor was cylindrical, electric current density distributed uneven. This paper used average electric current density (center plane interfaced between two electrodes with 50% useful volume each).+solution. A standard curve covered colority from 10° to 100° was drawn. The absorbency of the sample which had been centrifugated was measured at wavelength of 350nm. Colority was obtained by calculation [5]. Azoreductase activity was measured by TTC deoxidation method [6]. III. RESULTS AND DISCUSSION The test device adopted domestic sewage inoculation sludge and hanged membrane for 41 days. After the start-up of the device, the results from the contrastively experiments between BEH-BCO process and BH-BCO process to treat active brilliant red X-3B wastewater in electric current density 0.071, 0.048, 0.020 mA/cm2 were showed in figure 2- figure 5. A. Azo dye concentration variety Figure 2 shows the variety of azo dye mass concentration of inflow and effluent to and from every reactor in different electric current density. It depicts that, comparing to the single biological method, treating active brilliant red X-3B by BEH-BCO process has better efficiency. The azo dye concentration of effluent from BEH-BCO process increased with the electric current density declined. When the electric current density was 0.071mA/cm2, the average removal ratio of dye concentration by BEH-BCO process was 98.77%. In BH-BCO process, because of the dye concentration of inflow was too high and the DO in hydrolysis reactor was lower, the bacteria in hydrolysis reactor were restrained. As a result, the average removal ratio of dye concentration was 9.65%.A.BEH-BCO B.BH-BCO 1.Wastewater tank 2..Dosing pump 3.Power 4. BEH reactor 5. Graphite electrode 6 .Packing 7. Iron electrode 8. BCO reactor 9. Aerated conduit 10. Effluent 11. Air compressor 12. Air distributor 13. Time controller 14. Disposed sludge 15. BH reactorFigure 1. Schematic of the experiment apparatusB. Azo dye wastewater Component of simulated azo dye wastewater for experiment is showed in Table I.TABLE ICODCr (mg/L)EXPERIMENTAL WASTEWATER COMPONENTNH3-N/ (mg/L) active brilliant red X-3B/(mg/L) colority pHFigure 2.Variety of Azo dye concentration 122.84-206.41 6.3-7.145.5-128.62.06-6.6240.88-66.26B. Colority varietyC. Analysis method CODCr was measured by fast digestion spectrophotometric method. NH3-N was measured by Nessler's reagent spectrophotometric method. The azo dye concentration was measured at wavelength of 540nm by spectrophotometric method. The sample of the wastewater was centrifugated by a centrifuge at a speed of 4000 revolutions per minute about 10 min. Colority was measured by spectrophotometric method. The dilute H2SO4 solution (ca. 0.02 mol/L) made up of K2Cr2O7 and CoSO4 was used as standard solution for colority measurement. The wavelength of measurement was defined at 350 nm, which was the maximum absorbency of the standardFigure 3. Variety of colorityFigure 3 was the variety of colority of inflow and effluent to and from every reactor in different electric current density. It showed that when electric current density was 0.048 and 0.071mA/cm2, bioelectrochemical technology had a good effect on decolorization to active brilliant red X-3B wastewater. When the electric current density was 0.071mA/cm2, the average decolorization rate reached 91.39%. Biological method had a low decolorization effect to active brilliant red X-3B wastewater. The average decolorization rate was only 18.21%. When the electric current density was 0.020mA/cm2, the colority of the effluent from BCH reactor was higher than the inflow to BCH reactor. The reasons were as follows: on the one hand, when the electric current density was lower, the loose biofilm and the free bacterium in reactor made colority increase; on the other hand, because of the lower electric current density, the OH—produced in cathode was too less, but the Fe3+ produced in anode was excessive, the color of Fe3+ made colority increase. C. Organics varietywhich indicated that hydrolysis process was more efficiency. When electric current density was 0.071mA/cm2, the average removal ratio of NH3-N was 90.41% by bioelectrochemical technology, the average removal ratio of NH3-N was 85.69% by biological method.Figure 5. Variety of ammonia nitrogenousIV.RESEARCH OF PRINCIPLEA. UV-visible absorption spectrum Analysis Azo dye’s active brilliant red X-3B has absorption peaks in the wavelength of 280 nm, 320 nm and 540 nm respectively. The absorption peaks 540 nm in visible light was caused by the n→π system which connected benzene ring to naphthalene ring by azo double-bond. In ultraviolet, the absorption peaks in 280nm, 320nm wavelengths were caused by benzene ring, naphthalene ring, dichloro-methoxy-triazine and so on [7]. When electric current density was 0.071mA/cm2， The analysis of UV-visible absorption spectrum for the influent and the effluent is shown in figure 7.4.0Figure 4. Variety of organics3.5Absorbance(AU)Raw water By BEH By BCO(BEH-BCO) By BH By BCOFigure 4 shows the variety of organics of inflow and effluent to and from every reactor in different electric current density. It depicts that along with the electric current density decreased, the CODCr of effluent from BEH increased. When electric current densities were 0.071, 0.048, 0.020mA/cm2, the average removal ratio of CODCr was 50.08%, 30.11%, 24.71%, respectively. When electric current density was 0.071mA/cm2, the average removal ratio of CODCr was 69.98% by bioelectrochemical technology, and the average total removal ratio of CODCr was 31.32% by biological method. D. Ammonia nitrogenous variety Figure 5 shows the variety of ammonia nitrogenous of inflow and effluent to and from every reactor in different electric current density. As shown in Figure 5, the NH3-N of the effluents from BEH reactor and BH reactor are all higher than raw water. It was because azo double bonds of dye molecule was broken in hydrolysis process, became small molecule organics. Benzenering, naphthalene nucleus or dichlotriazine active group of the dye molecule was broken and ammonia nitrogenous was liberated. So ammonia nitrogenous concentration in the effluent was more than that in the influent,3.0 2.5 2.0 1.5 1.0 0.5 0.0 200 250 300 350 400 450 500Wavelength(nm)550 600650 700Figure 7. UV-visible absorption spectrum of azo dye wastewaterAs shown in figure 7. After the treatment of biological method, the absorption peaks were not changed obviously. It showed that the structure of active brilliant red X-3B was not changed. But, after the treatment by BEH-BCO process, the absorption peaks decreased obviously, and the absorption peaks at 540nm was almost zero. Consider the molecular structure of active brilliant red X-3B, the absorption peaks nearby at 280nm and 320nm are decreased, which explained that benzene ring, naphthalene ring, dichloro methoxy triazine were degraded, unsaturated ring was opened. The absorptionpeaks at the wavelength of 540nm declined obviously, it explained that azo double-bond was opened. But at 215nm, the absorption peaks rose, It explained that there were some aromatic ring compounds in the wastewater [8]. B. Redox potential analysis In order to research the redox potential of BEH and BH, we got some mixed liquors from BEH and BH respectively, then measured the redox potential by potentiometric titrator. The reaction between azo dyes and reduced electronic carrier is nonspecific reduction process. The occurrence of reaction was decided on the redox potential of redox intermediates and azo compound, namely determined by the redox potential (-180mV ~ -430mV) of cell redox cofactor, the NAD(P)H, and the potential of azo compound[9].TABLE II Rector BEH BH REDOX POTENTIAL Electric Current Density (mA/cm2) 0.024 0.048 0.071 Redox Potential (mV) -217 -185 -202 -152V. CONCLUSIONS • Compared with the single biological method, electrochemical function of DC micro-electric field and biological function produced synergy for the degradation processes of active brilliant red X-3B by bioelectrochemical technology. This method improved the activity of microorganism, and promoted the dye biodegradation. In the biodegradation process of azo dye active red X-3B by bioelectrochemical technology, the treatment effect increased with the increase of current density. The treatment efficiency of active brilliant red X-3B was increased with the increase of electric current density. The structure of active brilliant red X-3B was destroyed in bioelectrochemical hydrolysis reactor and turned into readily biodegradable small molecular organic compound. But in biological method, because the concentration of dye wastewater was too high, and the dissolved oxygen in hydrolysis reactor was lower, the bacteria in hydrolysis reactor were restrained. It made the structure of active brilliant red X-3B changed smaller.•••Table II was the redox potential of BEH and BH. Table II showed that, the redox potential of mixed liquor in BEH was about -200mV. It was in the range of azo compound redox requirement (-180mV ～ -430mV). The redox potential of mixed liquor in BH was about -152mV. It was not in the range of azo compound redox requirement, and also not in the range of hydrolysis reactor running normally (about 0mV). C. Azoreductase analysisThe first step of azo dyes biodegradation was the key to open azo double-bond, and produce aromatic ammonia. This step was finished by catalysis of azoreductase[10]. The decolorization ability of bacteria to the dyes mainly depended on the effect of azoreductase. This experiment analyzed azoreductase activity of the bacterium from each reactor. Measured each water sample in the same reactor three times, the average results were in table III.TABLE III BEH (mg/L·h) 55.33 AZOREDUCTASE ACTIVITY IN EACH REACTOR BCO （BEH-BCO） (mg/L·h) 3.17 BH (mg/L·h) 1.68 BCO (mg/L·h) 1.68As shown in table III, azoreductase activity in BEH-BCO system was higher than in BH-BCO system. The azoreductase activity in BEH reactor was 55.33 mg/L·h. It explained that due to the effect of direct current field, the rate of biochemical reactions was enhanced, microbial activity was better. It also explained that except for the electrochemical function and biodegradation function, the electric field could stimulate the activity of microbe and enhance the efficiency of dye degradation.Mi Yilei, Fan Jinhong, Ma Luming. Research on removal of azo dye by bioelectrochem ical technology [J]. Chinese Journal of Environmental Engineering, 2009, 3(8): 1457-1461. [2] Wang Hui. Recent Advance in Biological Treatment of Dyeing Wastewater [J]. Journal of Xia Men University (Natural Science), 2008, 12: 286-290. [3] Liang Hong, Zeng Kangmei. Progress in the Dyes Wastewater Treatment Processes [J]. Journal of Sichuan University of Science & Engineering, 2003, 6: 20-24. [4] Zhang Changsheng, Xue An, Zhao Huazhang. Progress in the studies of electrical bio-technology in environmental engineering[J]. Industrial Water Treatment, 2008, 28(3): 1-5. [5] Yao Guo, Wang Jian wei.Determination of Colority of Sewage Water[J]. PTCA (PART B: CHEM. ANAL.), 2008, 44:61-64. [6] Zhou Chunsheng,Yin Jun, Meng Lin. Study of Method for Determing TTC-Dehydrogenase [J].Journal of Jilin Architectural Civil Engineering Institute, 1995, 3 (1) [7] Brewster M, Fuss F, Tebbens J, et al. Spectrophotometer analysis of electrochemically treated simulated disperse dye bath effluent [M].AATCC, Book of papas, 1992: 17-19· [8] Zhao Yuhua ， Dong Ruijiao. Hydrolyzing Mechanism on Azo Dye Wastewater Treatment by Anaerobic Bioreactor [J]. Journal of Shenyang Jianzhu University (Natural Science), 2009, 25(2):325-328. [9] Liu Guangfei, Zhou Jiti, Wang Jing. Progress on Degradation of Azo Dyes by Bacteria and Azoreductase [J]. Environmental Science & Technology, 2006, 29(4): 112-114 [10] Ftrojt L， Strasak L， Vetted V， et a1． Comparison of the low—frequency magnetic field effects on bacteria Escherichia coli ， Leclercia adecarboxylata and Staphylococcus aureus[J] ．Bioelectrochemistry， 2004，63(12) ：337~341 [11] Chang Y H D， Grodzinsky A J ， Wang D I C ． Augmentation of masstransfer through electrical means for hydrogel-entrapped Escherichia colicultivation[J]．Biotechnol Bioeng， 1995， 48(2) ： 149~157 [12] Laleh Loghavi，B.S．electric field on growth kinetics，cellmembrane permeabilization，and frequencyresponse of microorganisms．The Ohio State University，2008[1]。
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Key words: Sewage treatment, fixed-film and suspended-growth, Activated sludge Origins of sewage Sewage is created by residences, institutions, and commercial and industrial
stream, river, bay, lagoon or wetland, or it can be used for the irrigation of a golf
course, green way or park. If it is sufficiently clean, it can also be used for
waste stream (or treated effluent) and a solid waste or sludge suitable for discharge or
reuse back into the environment. This material is often inadvertently contaminated
Conventional sewage treatment may involve three stages, called primary,
secondary and tertiary treatment. Primary treatment consists of temporarily holding
(effluents) and domestic. It includes physical, chemical, and biological processes to
remove physical, chemical and biological contaminants. Its objective is to produce a
common in the developed world, with greywater being permitted to be used for
watering plants or recycled for flushing toilets. A lot of sewage also includes some
compounds, animal waste, and oil and grease. Some jurisdictions require stormwater 2 to receive some level of treatment before being discharged directly into waterways.
the sewage treatment system, causing a spill or overflow. It is preferable to have ቤተ መጻሕፍቲ ባይዱ
separate storm drain system for stormwater in areas that are developed with sewer
Examples of treatment processes used for stormwater include sedimentation basins,
wetlands, buried concrete vaults with various kinds of filters, and vortex separators (to
1 Sewage treatment Abstract：
：：
：Sewage treatment, or domestic wastewater treatment, is the process of
removing contaminants from wastewater and household sewage, both runoff
necessary, and subsequently more expensive, treatment facilities. In addition, heavy
storms that contribute more flows than the treatment plant can handle may overwhelm
Secondary treatment is typically performed by indigenous, water-borne
micro-organisms in a managed habitat. Secondary treatment may require a separation
bar screen in modern plants serving large populations, whilst in smaller or less
modern plants a manually cleaned screen may be used. The raking action of a
process to remove the micro-organisms from the treated water prior to discharge or
tertiary treatment. Tertiary treatment is sometimes defined as anything more than
include stormwater runoff. Sewage systems capable of handling stormwater are
known as combined systems or combined sewers. Such systems are usually avoided
pump stations to a municipal treatment plant (see sewerage and pipes and
infrastructure). Sewage collection and treatment is typically subject to local, state and
systems.
As rainfall runs over the surface of roofs and the ground, it may pick up various
contaminants including soil particles and other sediment, heavy metals, organic
surface water from roofs or hard-standing areas. Municipal wastewater therefore
includes residential, commercial, and industrial liquid waste discharges, and may
the sewage in a quiescent basin where heavy solids can settle to the bottom while oil,
grease and lighter solids float to the surface. The settled and floating materials are
remove coarse solids). Process overview Sewage can be treated close to where it is created (in septic tanks, biofilters or
aerobic treatment systems), or collected and transported via a network of pipes and
since they complicate and thereby reduce the efficiency of sewage treatment plants
owing to their seasonality. The variability in flow also leads to often larger than
establishments. Raw influent (sewage) includes household waste liquid from toilets,
baths, showers, kitchens, sinks, and so forth that is disposed of via sewers. In many
groundwater recharge or agricultural purposes. Pre-treatment Pre-treatment removes materials that can be easily collected from the raw
wastewater before they damage or clog the pumps and skimmers of primary treatment
clarifiers (trash, tree limbs, leaves, etc). 3 Screening The influent sewage water is strained to remove all large objects carried in the
sewage stream. This is most commonly done with an automated mechanically raked