给排水毕业设计外文翻译及原文

Nutrient removal in an A2O一MBR reactor with sludge reduction

J. Rajesh Banu, Do I

Department of Civil and Environmental Engineering Sungllyunllwan University, 300, Chunchun-dong, Jangan-gu, Suwon-Si 440-746, Repuhlic of Korea

ARTICLE INFO

Article history:

Received 20 July 2008

Received in revised form 11 December 2008

Accepted 15 December 2008

Available online 25 February 2009

Keywords:

A2O reactor

MBR

Nutrient removal

TMP

ABSTRACT

In the present study, an advanced sewage treatment process has been developed by incorporating excess sludge reduction and phosphorous recovery in an A2O-MBR process. The A2O-MBR reactor was operated at a flux of 77 LMH over a period of 270 days. The designed flux was increased stepwise over a period of two weeks. The reactor was operated at two different MLSS range. Thermo chemical digestion of sludge was carried out at a fixed pH (11)and temperature (75℃) for 25% COD solubilisation. The released pbospborous was recovered by precipitation process and the organics was sent back to anoxic tank. The sludge digestion did not have any impact on COD and TP removal efficiency of the reactor. During the 270 days of reactor operation, the MBR maintained relatively constant transmembrane pressure. The results based on the study indicated that the proposed process configuration has potential to reduce the excess sludge production as well as it didn't detonated the treated water quality.

@2008 Elsevier Ltd. All rights reserved.

1. Introduction

Excess sludge reduction and nutrients removal are the two important problems associated with wastewater treatment plant. MBR process has been known as a process with relatively high decay rate and less sludge production due to much longer sludge age in the reactor (Wen et al., 2004). Sludge production in MBR is reduced by 28-68%, depending on the sludge age used (Xia et al., 2008). However, minimizing the sludge production by increasing sludge age is limited due to the potential adverse effect of high MLSS concentrations on membrane (Yoon et al., 2004). This prob- lem can be solved by introducing sludge disintegration technique in MBR (Young et al., 2007). Sludge disintegration techniques have been reported to enhance the biodegradability of excess sludge (Vlyssides and Karlis, 2004). In overall, the basis for sludge reduction processes is effective combination of the methods for sludge disintegration and biodegradation of treated sludge. Advances in sludge disintegration techniques offer a few promising options including ultrasound (Guo et al., 2008), pulse power (Choi et al.,2006), ozone (Weemaes et al., 2000), thermal (Kim et al., 2003), alkaline (Li et al., 2008) acid (Kim et al., 2003) and thermo chemical

(Vlyssides and Karlis, 2004). Among the various disintegration techniques, thermo chemical was reported to be simple and cost effective (Weemaes and Verstraete, 1998). In thermal-chemical hy- drolysis, alkali sodium hydroxide was found to be the most effective agent in inducing cell lysis (Rocker et al., 1999).

Conventionally, the nutrient removal was carried out in an A2O process. It has advantage of achieving, nutrient removal along with organic compound oxidation in a single sludge configuration using linked reactors in series (Tchobanoglous et al., 2003). The phosphoroes removal happens by subjecting phosphorous accumulating organisms (PAO) bacteria under aerobic and anaerobic conditions (Akin and Ugurlu, 2004). These operating procedures enhance predominance PAO, which are able to uptake phosphorous in excess. During the sludge pretreatment processes the bound phosphorous was solubilised and it increases the phosphorous concentration in the effluent stream (Nishimura, 2001).So, it is necessary to remove the solubilised phosphorus before it enters into main stream. Besides, there is a growing demand for the sustainable phosphorous resources in the industrialized world. In many developed countries, researches are currently underway to recover the phosphoroes bound in the sludge's of enhanced biological phosphorus removal system (EBPR). The released phosphorous can be recovered in usable products using calcium salts precipitation method. Keeping this fact in mind, in the present study, a new advanced wastewater treatment process is developed by integrating three processes, which are: (a) thermo chemical pretreatment in MBR for excess sludge reduction (b) A2O process for biological nutrient removal (c) P recovery through calcium salt precipitation. The experimental data obtained were then used to evaluate the performance of this integrated system.

2. Methods

2.1. Wastewater

The synthetic domestic wastewater was used as the experimental influent. It was basically composed of a mixed carbon source, macro nutrients (N and P), an alkalinity control (NaHCO3) and a microelement solution. The composition contained (L-') 210 mg glucose, 200 mg NH4C1, 220 mg NaHCO3, 22一34 mg KH2PO4, microelement solution (0.19 mg MnCl2 4H20, 0.0018 mg ZnCl22H2O, 0.022 mg CuCl22H2O, 5.6 mg MgSO47H2O, 0.88 mg FeCl36H2O, 1.3 mg CaCl2·2H2O). The synthetic wastewater was prepared three times a week with concentrations of 210±1.5 mg/L chemical oxygen demand (COD), 40±1 mg/L total nitrogen (TN) and 5.5 mg/L total phosphorus (TP).

2.2. A2O-MBR

The working volume of the A2O-MBR was 83.4 L. A baffle was placed inside the reactor to divide it into anaerobic (8.4 L) anoxic (25 L) and aerobic basin (50 L). The synthetic wastewater was feed into the reactor at a flow rate of 8.4 L/h (Q) using a feed pump. A liquid level sensor, planted in aerobic basin of A2O-MBR controlled the flow of influent. The HRT of anaerobic, anoxic and aerobic basins were 1, 3 and 6 h, respectively. In order to facilitate nutrient removal, the reactor was provided with two internal recycle (1R). IRl (Q= 1)connects anoxic and anaerobic and IR 2 (Q=3) was between aerobic and anoxic. Anaerobic and anoxic basins were provided with low speed mixer to keep the mixed liquid suspended solids (MLSS) in suspension. In the aerobic zone, diffusers were used to generate air bubbles for oxidation of organics and ammonia. Dissolved oxygen (DO) concentration in the aerobic basin was maintained at 3.5 mg/1 and was monitored continuously through online DO meter. The solid liquid separation happens in aerobic basin with the help of five flat sheet membranes having a pore size of 0.23 pm. The area of

each membrane was 0.1 m2. They were connected together by a common tube. A peristaltic pump was connected in the common tube to generate suction pressure. In the common tube provision was made to accommodate pressure gauge to measure transmembrane pressure (TMP) during suction. The suction pump was operated in sequence of timing, which consists of 10 min switch on, and 2 min switch off.

2.3. Thermo chemical digestion of sludge

Mixed liquor from aerobic basin of MBR was withdrawn at the ratio of 1.5% of Q/day and subjected to thermo chemical digestion. Thermo chemical digestion was carried out at a fixed pH of 11(NaOH) and temperature of 75℃for 3 h. After thermo chemical digestion the supernatant and sludge were separated. The thermo-chemically digested sludge was amenable to further anaerobic bio-degradation (Vlyssides and Karlis, 2004), so it was sent to theanaerobic basin of the MBR

2.4. Phosphorus recovery

Lime was used as a precipitant to recover the phosphorous in the supernatant. After the recovery of precipitant the content was sent back to anoxic tank as a carbon source and alkalinity supelement for denitrification.

2.5. Chemical analysis

COD, MLSS, TP, TN of the raw and treated wastewater were analyzed following methods detailed in (APHA, 2003). The influent and effluent ammonia concentration was measured using an ion-selective electrode (Thereto Orion, Model: 95一12). Nitrate in the sample was analyzed using cadmium reduction method (APHA, 2003).

3. Results and discussion

Fig. 1 presents data of MLSS and yield observed during the operational period of the reactor. One of the advantages of MBR reactor was it can be operated in high MLSS concentration. The reactor was seeded with EBPR sludge from the Kiheung, sewage treatment plant, Korea. The reactor was startup with the MLSS concentration of 5700 mg/L. It starts to increase steadily with increase in period of reactor operation and reached a value of 8100 mg/L on day 38. From then onwards, MLSS concentration was maintained in the range of 7500 mg/L by withdrawing excess sludge produced and called run I. The observed yields (Yobs) for experiments without sludge digestion (run I) and with sludge digestion were calculated and given in Fig. 1. The Yobs for run I was found to be 0.12 gMLSS/gCOD. It was comparatively lower than a value of 0.4 gMLSS/gCOD reported for the conventional activated sludge processes (Tchoba-noglous et al., 2003). The difference in observed yield of these two systems is attributed to their working MLSS concentration. At high MLSS concentration the yield observed was found to be low (Visva-nathan et al., 2000). As a result of that MBR generated less sludge.The presently used MLSS ranges (7.5一10.5 g/L) are selected on the basis of the recommendation by Rosenberger et al. (2002). In their study, they reported that the general trend of MLSS increase on fouling in municipal applications seems to result in no impact at medium MLSS concentrations (7一12 g/L).

The thermo chemical sludge digestion was started on day 70 by withdrawing sludge at the ratio of 1.5％ Q/day. The sludge digestion period was divided into two phases namely, run II (day 70-139) and run III (day 140-210). During run II, the MLSS concentration in MBR was maintained around 7500 mg/L and for run III it was maintained around 10500 mg/L. Both of these two runs (II and III) demonstrate the role of sludge disintegration in controlling the excess sludge production. The Yobs for run II and III were found to be 0.03gMLSS/gCOD, respectively. It

accounts for 58% and 75% of sludge reduction when compared to run I. The observed yield for run III was found to be lower than run II. This is due to the fact that at run III more amount of biosolids were subjected to be sludge digestion.

It is evident from the data that the COD removal efficiency of A2O system remains unaffected before and after the introduction of sludge digestion practices. A test analysis showed that the differences between the period without sludge digestion (run I) and with sludge digestion (run II and III) are not statistically significant.

However, it has been reported that, in wastewater treatment processes including disintegration-induced sludge degradation, the effluent water quality is slightly detonated due to the release of nondegradable substances such as soluble microbial products (Ya-sui and Shibata, 1994; Salcai et al., 1997; Yoon et al., 2004). During the study period, sCOD concentration in the aerobic basin of MBR was in the range of 18-38 mg/L and corresponding organic concentration in the effluent was varied from 4 to 12 mg/L. From this data it can be concluded that the membrane separation played an important role in providing the excellent and stable effluent quality. Phosphorus is the primary nutrient responsible for algal bloom and it is necessary to reduce the concentration of phosphorus in treated wastewater to prevent the algal bloom. Fortunately its growth can be inhibited at the levels of TP well below 1 mg/L (Mer-vat and Logan, 1996).

Fig. 2 depicts TP removal efficiency of the A2O-MBR system during the period of study. It is clearly evident from the figure that the TP removal efficiency of A/O system was remains unaffected after the introduction of sludge reduction. In the present study, the solubilised phosphorous was recovered in the form of calcium phosphate before it enters into main stream. So, the possibility of phosphorus increase in the effluent due to sludge reduction practices has been eliminated. The influent TP concentration was in the range of 5.5 mg/L. During the first four weeks of operation the TP removal efficiency of the system was not efficient as the TP concentration in the effluent exceeds over 2.5 mg/L. The lower TP removal efficiency during the initial period was due to the slow growing nature of PAO organisms and other operational factors such as anaerobic condition and internal recycling. After the initial period, the TP removal efficiency in the effluent starts to increase with increase in period of operation. TP removal in A2O process is mainly through PAO organisms. These organisms are slow growing in nature and susceptible to various physicochemical factors (Carlos et al., 2008). During the study period TP removal efficiency of the system remains unaffected and was in the range of 74-82%.。From the results it can be concluded that PAO organisms were not affected by thermo chemical pretreatment and TP in the effluent was found to be less than 1 mg/L throughout the study period.

Fig.3 presents data on phosphorus profile of the sludge during the thermo chemical digestion. In

the process of thermo chemical digestion, the bound phosphorous in the biosolids was solubilised and released into the solution. The phosphorous solubilisation was found to be in the range of 45-50%. The alkali increases the pH of the digested mixed liquor and was in the range of 9.2-9.8. This high pH range was favorable for phosphorous removal using calcium salt. The phosphorous removal in the supernatant was carried out using lime at a mole ratio of 2.1:1.

Fig. 4 explain nitrification and denitrification processes in the A2O-MBR system. Nitrification is the primary important process in removing total nitrogen from the wastewater. Incomplete nitri- fication decreases TN removal efficiency of the system (Morita et al., 2007 and Choi et al., 2008). Dissolved oxygen (DO) is the principal parameter that controls nitrification. Nitrification efficiency goes down when DO decreases below 2.5 mg/1 (Bane et al., 2008). To ensure complete nitrification the DO in the aerobic basin was maintained around 3.5 mg/1. In the second step of nitrogen removal process, the nitrate formed by nitrification was reduced into nitrogen gas in the absence of dissolved oxygen called anoxic denitrification (Peng et al., 2006). From Fig. 4 it is evident that not all nitrate species enter into anoxic basin get reduced. The nitrate

concentration was found to be in the range of 4-6 mg/L indicating denitrification process was incomplete.

Fig. 5 explains TN removal efficiency of the A2O-MBR system. It is evident from the figure that the nitrogen removal efficiency of A2O system was remain unaffected during the entire period of study. The influent TN was found to be 40 mg/L. During the initial phase of operation (1-20 days) the TN removal was in the range of 50-55%. Sludge disintegration did not have any influence over TN removal efficiency of the system and was varied between 60% and 67% throughout the study period. TN concentration in the effluent was found to be in the range of 14-18 mg/L.

During the study period, the transmembrane pressure increased slowly and at the end of 210 days of reactor operation the TMP was found to be 6-cmHg. It appears that the sludge disintegration system does not play role in membrane fouling. Similar to our study, while working on sludge reduction practices in MBR, Young et al. (2007) have reported that the alkaline treatment of sludge didn't cause membrane fouling.

4. Conclusions

Stable operation of MBR process was possible without significant accumulation of biomass when a part of the biological solids were disintegrated with alkali at pH 11 and temperature 75℃Thermo chemical sludge digestion favors the recovery of phosphorous in the supernatant using calcium salts. The system can run for a long period of time with any further detoriation in TP removal efficiency. Further studies focusing on fate of disintegrated sludge are in progress. Acknowledgements

This work was partly supported by the GS group of companies and Brain Korea 21 program from the Korean Ministry of Education

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Laminar and Turbulent Flow Observation 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 inertia

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外文资料名称： Design and performance evaluation of vacuum cleaners using cyclone technology 外文资料出处：Korean J. Chem. Eng., 23(6), (用外文写) 925-930 (2006) 附件： 1.外文资料翻译译文 2.外文原文

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给排水专业毕业设计英文翻译--中英文对照

河北建筑工程学院 毕业设计（论文）外文资料翻译 系别：城建系 专业：给水排水工程 班级： 姓名： 学号： 外文出处：Wan Fang foreign languages （用外文写） literature datebase 附件：1、外文原文；2、外文资料翻译译文。

1、外文原文（复印件） 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 SEWERAGE 1) 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 a room, 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

本科毕业设计外文翻译

Section 3 Design philosophy, design method and earth pressures 3.1 Design philosophy 3.1.1 General The design of earth retaining structures requires consideration of the interaction between the ground and the structure. It requires the performance of two sets of calculations: 1）a set of equilibrium calculations to determine the overall proportions and the geometry of the structure necessary to achieve equilibrium under the relevant earth pressures and forces; 2）structural design calculations to determine the size and properties of thestructural sections necessary to resist the bending moments and shear forces determined from the equilibrium calculations. Both sets of calculations are carried out for specific design situations (see 3.2.2) in accordance with the principles of limit state design. The selected design situations should be sufficiently Severe and varied so as to encompass all reasonable conditions which can be foreseen during the period of construction and the life of the retaining wall. 3.1.2 Limit state design This code of practice adopts the philosophy of limit state design. This philosophy does not impose upon the designer any special requirements as to the manner in which the safety and stability of the retaining wall may be achieved, whether by overall factors of safety, or partial factors of safety, or by other measures. Limit states (see 1.3.13) are classified into: a) ultimate limit states (see 3.1.3); b) serviceability limit states (see 3.1.4). Typical ultimate limit states are depicted in figure 3. Rupture states which are reached before collapse occurs are, for simplicity, also classified and

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毕业设计外文翻译

毕业设计（论文） 外文文献翻译 题目：A new constructing auxiliary function method for global optimization 学院： 专业名称： 学号： 学生姓名： 指导教师： 2014年2月14日

一个新的辅助函数的构造方法的全局优化 Jiang-She Zhang，Yong-Jun Wang https://www.360docs.net/doc/a73319597.html,/10.1016/j.mcm.2007.08.007 非线性函数优化问题中具有许多局部极小，在他们的搜索空间中的应用，如工程设计，分子生物学是广泛的，和神经网络训练．虽然现有的传统的方法，如最速下降方法，牛顿法，拟牛顿方法，信赖域方法，共轭梯度法，收敛迅速，可以找到解决方案，为高精度的连续可微函数，这在很大程度上依赖于初始点和最终的全局解的质量很难保证．在全局优化中存在的困难阻碍了许多学科的进一步发展．因此，全局优化通常成为一个具有挑战性的计算任务的研究． 一般来说，设计一个全局优化算法是由两个原因造成的困难：一是如何确定所得到的最小是全球性的（当时全球最小的是事先不知道），和其他的是，如何从中获得一个更好的最小跳．对第一个问题，一个停止规则称为贝叶斯终止条件已被报道．许多最近提出的算法的目标是在处理第二个问题．一般来说，这些方法可以被类?主要分两大类，即：（一）确定的方法，及（ii）的随机方法．随机的方法是基于生物或统计物理学，它跳到当地的最低使用基于概率的方法．这些方法包括遗传算法（GA），模拟退火法（SA）和粒子群优化算法（PSO）．虽然这些方法有其用途，它们往往收敛速度慢和寻找更高精度的解决方案是耗费时间．他们更容易实现和解决组合优化问题．然而，确定性方法如填充函数法，盾构法，等，收敛迅速，具有较高的精度，通常可以找到一个解决方案．这些方法往往依赖于修改目标函数的函数“少”或“低”局部极小，比原来的目标函数，并设计算法来减少该?ED功能逃离局部极小更好的发现． 引用确定性算法中，扩散方程法，有效能量的方法，和积分变换方法近似的原始目标函数的粗结构由一组平滑函数的极小的“少”．这些方法通过修改目标函数的原始目标函数的积分．这样的集成是实现太贵，和辅助功能的最终解决必须追溯到

建筑 给排水 外文翻译 英文文献 多层住宅建筑给排水设计的几个问题

译文来源：美国PE杂志建筑给排水工程师2010年第10期 The multilevel residential housing is given and drains off water several questions designed Summary : This text give and drain off water on multilevel residential housing design supply water the exertion of the tubular product , Way of laying of pipeline, water gauge produce family set up, establishment and air conditioner condensation water of pot-type boiler discharge issue goes on the discussion , And put forward some concrete views. Keyword: Skyscraper, supply water the tubular product , the pipeline is laid, The water gauge, the solar water heater The skyscraper is simple with its auxiliary facility, the fabrication cost is low, the characteristic such as being convenient of estate management, Receive the welcomes of the real estate developer and vast resident of small and medium-sized cities very much. How project planning and design of inhabited region, scientific and technological industry of comfortable house, lead the request according to 2000, Improve the design level of the house, build out a comfortable living space for each household, It is each designers duty. As the heart of the house --The kitchen, bathroom, is that the function is complicated, hygiene, safe and comfortable degree are expected much, It is miscellaneous to build, the space expecting much in technology. So, the designer must consider synthetically with the idea and method of global design that the kitchen, bathroom give installation of the drainage pipeline and equipment,etc. . Give and drain off water on skyscraper design supply water exertion, to lay pipeline of tubular product, water gauge produce family set up, establishment and empty of pot-type boiler now Transfer condensation water discharge issue discuss together with colleagues. ( 1)supply water tubular product select problem for use Traditional watersupply tubular product adopt zinc-plated steel tube generally, because zinc-plated steel tube exchange the corrosion, Use short-lived , use for and send domestic water can satisfied with water quality sanitary standard shortcoming, Ministry of Construction is popularizing the application of the feed pipe of plastics energetically . A lot of districts and cities have already expressed regulations: Forbid designing and using the zinc-plated steel tube , use widely the feed pipe of plastics. The plastics supply water In charge of compared with metal pipeline, light, it is fine to able to bear the intensity of keeping, Send obstruction little liquid , able to bear chemistry better to corrode performance, it is convenient to install, The steel energy-conservation of the province, merit of having long performance life etc.. Supply water and use plastics pipeline: Hard polyvinyl chloride( PVC-U), high density polyethylene( HDPE), pay and unite polyethylene( PEX) , modify the polypropylene( PP-R, PP-C), gather butene( PB), aluminium mould and compound and in charge of and the steel is moulded and compound and is managed etc.. Choice of tubular product economic comparative