外文翻译
基于PLC的控制系统在污水处理中的应用
介绍了以PLC为核心的分布式控制系统在污水处理系统中的应用。具体叙述了控制系统的结构、任务分配及实现、控制方式和程序设计思想.控制系统采用集中监测管理、分散控制的方式，上位机负责现场设备的远程控制和监视，软件采用Intouch7. 0编制。PLC本地站负责对具体的工艺、设备、主要被控参数进行控制及采集各种运行数据，程序设计采用具有在线跟踪和离线仿真功能的Concept 2. 2XL软件。上位机与PLC之间采用组网简单、运行速度快、通信稳定性强的MB+网。整个控制系统成功地解决了PLC在污水处理中的自动化控制问题，提高了污水处理设备运行效率和管理水平。
近年来，为了实现高质量、低消耗、稳定可靠的运行。国内外许多污水处理厂采用了现代先进控制技术和计算机技术，从而构成计算机监督、控制、管理系统.使系统优化运行。而可编程逻辑控制器（PLC）则是以微处理器为核心。综合了计算机技术自动控制技术和通信技术而发展起来的一种新型、通用的自动控制装置。具有结构简单、性能优越、可靠性高、灵话通用、易于编程、使用方便等优点等。银川市第一污水处理厂采用了SBR工艺及以PLC为核心的控制系统，日处理污水10 x 104 t处理后的达标污水可用于农业灌溉。
1 控制系统结构
控制系统采用“集中监测管理，分散控制”的方式。模拟屏、上位机、集线器、打印机位于中控室，二台PLC位于控制现场。采用这种结构可使生产过程中的信息能够集中管理，以实现整体操作、管理和优化。同时，也使得控制危险分散，提高系统可靠性。
1.1上位机
中控室的两台上位计算机采用PII级工控机，运行Windows NT操作系统。上位机负责现场设各的远程控制(全自动控制、自动控制、点动控制)和监视，利用Intouch7. 0工程软件包提供良好的人机对话界而，以查询方式从PLC获取有关参数和设备状态信息，以棒图形式在CRT上直观显示出来，同时打印必要的数据，供主控及管理人员指导生产。监控界而包括系统总图、系统分图、模拟量一览表、参数设置、报警窗、历史趋势、登录窗等界而.在系统总图里，运行人员能够监视所有控制设备的运行状态、设备事故及液位、流量等信号.在系统分图里，操作人员能够对所有控制设备进行单机点动运行操作、成组自动运行操作或全厂全自动操作并监视。同时上位机2兼做编程器.中控室另设置一个镶嵌式模拟屏，由上位机1控制，用以直观显示全厂工艺流程及主要参数值。
1.2 PLC站
根据污水处理的二部分，现场设备的远程控制输出和现场信号采集由二个PLC木地控制站完成。PLC1本地控制站控制格栅、污水提升泵房、曝气沉砂池等预处理部分。PLC2本地控制站控制污泥脱水、压滤机等部。PLC3本地控制站控制SBR生物处理部分.另外，在现场本地控制站各设1台操作终端设各，负责在本地对现场设各的控制(自动控制、点动控制)。
现场各个监控点的物理参数，包括水位、温度、流量、转速、电流等模拟量，由对应的一次仪表传感器或变送器检测出来并转变为4～20 mA电流信号，经屏蔽电缆送到各个子系统的PLC内，由PLC通过各种模块接口采样电信号。同样，
模拟量控制信号由PLC输出后以4～20mA电流形式送到执行机构，控制执行机构的动作。
施耐德公司的Modicon Quantum系列PLC为满足开放的、基于标准的网络连接和现场总线连接等应用技术提供了多种网络选择，支持Modbus,Mod-bus Plus（MB+），远程I/0, TCP/IP等网络连接，具有较强的灵活性。因此，污水处理中用到的PLC选用施耐德的Modicon Ouantum系列。
1.3通信
MB+协议是Modicon公司推出的一个开放式的采用IEEE802. 4令牌协议的现场总线通信5协议。MB+网络同其他网络相比具有组网简单、投资少、网络速度快、通信稳定性强等特点，它使计算机、控制器和其他数据源通过使用双绞线或光缆在整个网络上作为同位体进行通信。而Modicon Quantum系列PLC的CPU模块含有MB+通信口，因此，通信网络选用MB+网络.中控室的两台上位机、二个PLC本地控制站通过MB+网络连接在一起。PLC的CPU模块通过MB+通信口与两台上位机进行数据交换，采集上位监控系统的各种操作指令及现场检测信号和数据，经过分析处理，通过输出模块向控制对象输出控制信号；同时，PLC通过MB+网向上位机返回各种数据，上位机对数据进行运算处理，显示各种信号和打印各种报表。
2 PLC控制程序设计
系统有四种控制方式：本地手动控制，单一台设备点动控制，成组设备自动控制，全厂设备全自动控制。前二种方式一般只在设各调试或维修时使用，系统主要以全自动控制方式运行。在这种方式下，所有各类设备都由PLC按照预先编制的程序自动控制，不需要操作人员干预.各种现场数据通过PLC传至上位机，在上位机上描绘出来，使全厂的工艺、设备运行得到全面的控制。
PLC3站控制的生物处理部分是整个污水处理的关键部分，限于篇幅，仅以PLC3站的程序设计为例。
2.1控制过程
PLC3站用来控制从污水进入曝气池到处理后的污水流出曝气池的整个过程。在这个过程中，包括控制各种阀、泵、风机的顺序及定时开关和风机的转速调节等。曝气池是污水处理的核心构筑物，污水在池中是通过微生物的生物氧化作用来去除有机物的，水中氧的含量对污水的处理效果是至关重要的。根据SBR 工艺要求，曝气池内的溶解氧含量通常控制在1～3 mg/L范围内，在曝气阶段末溶解氧含量应不超过2 mg/L.含氧量过低或过高，均会影响出水质量。对日处理10 x 104 t的4组8池模式的SBR反应池，每组反应池配一台由变频器控制的风机，用于向两个曝气池轮流曝气供氧。在每个曝气池的不同地点设4块溶解氧测试仪，测量池中污水的含氧量，PLC每隔5 min检测一次曝气池内的溶解氧值，根据溶解氧的平均值来控制风机转速。若溶解氧低于设定下限时，调频风机转速增加5 % ；若溶解氧高于设定上限时，调频风机转速降低5 %.这样，就实现了曝气池供氧量的自动调节，既避免了不必要的能源损失，又优化了运行工艺。2.2 PLC程序设计
采用的编程软件是Concept 2. 2XL。Concept是基于Windows下的PLC编程工具，具有良好的用户界面，并具有在线跟踪及离线仿真功能。PLC3站的控制程序分为五个程序模块。
（1）公用程序模块——包括初始化部分、时分秒等时问脉冲单元、SBR反应周期设定、溶解氧设定等。
（2）开关量顺序控制模块——协调控制各个阀、泵、风机等设备的运行及相关故障的报警。SBR池的进气阀、进水阀、回流泵、剩余污泥泵由PLC根据污水处理周期的工艺时间段控制，出水阀由PLC根据工艺时间和超声液位仪的测量值来控制。
（3）断电保护模块——系统断电后，PLC将所有状态锁存，待加电后使PLC 恢复所保持的状态继续运行。
（4）通信模块——用来完成PLC与上位机的各种数据传送。
（5）溶解氧值自动调节模块——根据溶解氧值调节风机转速以及相关故障的报警。调节转速的目标是在整个曝气周期中，保证溶解氧的值为2 mg/L.采用的控制策略如下：曝气周期开始，风机以全速运行，以使溶解氧在较短的时问内达到2 mg/L，同时以5 min为周期检测溶解氧值。当溶解氧值大于2mg/L时，风机转速下降5 %；当溶解氧值小于2 mg/L时，风机转速上升5%.如果风机转速升到允许的最高转速时，溶解氧值还小于2mg/L，则维持最高转速。这种情况有可能在曝气周期的末期出现，但并不会明显地影响污水处理质量。
在曝气的整个周期内，随时监控变频器的输出电流值，使其不超过变频器的额定值。如遇到意外情况使输出电流超过额定值时，立即降低风机转速。如果风机转速降到允许的最低转速时，输出电流还超过额定值，则停风机，同时发出报警信号。
随着自动控制技术的发展，UNITANK工艺越来越得到广泛应用。目前以经验为主，以DO、时间、流量作为工艺控制参数，来调整曝气机的运行及排泥时间等，缺乏准确的数学模型来实现SBR法的更高层次的自动控制。有人曾提出以COD或DO为参数的模糊控制的思想。今后SBR法的自动控制的研究方向主要是寻找多个控制参数，既能反映进水的水质水量变化及反应过程中的降解情况，又能作为计算机控制参数。
PLC集顺序控制和过程控制于一体，具有可靠性高，使用方便、灵活，组网简单的特点，是实现中小规模工业自动化的有力工具。在污水处理中，基于PLC 的控制系统在实时性、可靠性、精确性等力一而满足了设计要求，保证了污水处理的顺利进行。
由于Internet的快速发展，希望能够通过Internet来访问污水处理厂的自控系统，只需要输入用户名和密码便可实现远程的Internet来对全厂的设备进行控制。同时通过Internet将污水处理厂的污水数据输送到国家环保总局或者市环保局，以便卜级部门对污水处理厂的管理。
译文：
Application of control system on the base of PLC in
sewage treatment
The paper introduces a distributed control system of sewage treatment, and the core of the system is PLC. The structure of the control system, the assignment and implementation of the tasks, the control scheme and the design concept of program are expounded. The way of central monitoring management and dispersing control is used by the control system; the long一distance control and monitoring of field equipment are uncharged of the upper computer; the software program of designs uses Intouch7. 0. The specific technology, equipment, the controlling of main parameter and several running data are uncharged of the PLC stations, and the software program of designs uses Concept 2. 2XL with online tracking and outline simulating. MB+ net is adopted by the communication between the upper computer and the PLC stations, with its simply building net, quickly running and stable communication. The automatic control of PLC has been successfully completed in sewage treatment, which has improved the operation efficiency and management level of sewage treatment equipment
Introduced to take PLC as the distribute type control system of core in the wastewater treatment system of apply。Concretely described the structure, mission of the control system an allotment and carry out, the way of control and the thought of the program design.The way controled the concentration monitor of the system adoption a management and scattered a control, the place of honor machine be responsible for the spot the long range of the equipments control and surveillance, software adoption Intouch7. 0 draw up.The PLC native station is responsible for to the concrete craft, equipments and is mainly controled parameter to carry on control and collect various movement data, the program design adoption have on-line follow with off-line imitate the Concept of true function 2. 2 XL software.Place of honor machine and of the PLC adoption set the net be quickly simple and circulate speed, correspond by letter the stability strong MB+net.The whole control system successfully solved the PLC controls a problem in the automation within wastewater treatment and raised a wastewater treatment equipments to circulate an efficiency and manage level.
Recently, for carrying out high quality, low consume, stable dependable movement.Domestic and international many wastewater treatment factorieses adopted a modern forerunner to control technique and calculator technique and constitute calculator direct, control thus, manage system.Make system excellent to turn movement.But the programmable logic controller(PLC) then take microprocessor as core.Synthesize the calculator technique automatically controls technique and correspondence technique but develops of a kind of new and in general use utomatic control device.Have structure simple, function superior, dependable sex Gao, work properly words in general use, be easy to plait distance, usage convenience etc.
advantage etc..The silver Chuan City the first wastewater treatment factory adopted a SBR craft and take PLC as the control system of core, day after handling the sewage 10 ×104 t the processing of reach mark sewage can used for an agriculture irrigation.
1 Control system structure
Control the way of "concentration monitor management, scatter a control" of the system adoption.The emulation hold, place of honor machine, gather a line machine, printer to Be located on medium control room, two set PLCs are located on control the spot.Adopt this kind of structure can make the information in the production line can centralized management with carry out whole operation, management with excellent turn.Also make to control dangerous dispersion in the meantime, raise the system credibility.
1.1 The upper computers
Medium control two calculator adoption PII class works of room to control machine, circulate the operate system of Windows NT.The place of honor machine be responsible for on the scene establish each long range control(full-automatic control, automatic control, order to move a control) with surveillance, make use of Intouch7. 0 engineering software packages provide a good person machine dialogue boundary but obtain concerning parameter and equipments appearance information from the PLC by searching a way, keep a view manifestation to come out on the CRT by good sketch type, print a necessary data in the meantime and be provided for lord to control and manager instruction produce.Supervise and control boundary but include the system total diagram, system cent diagram, imitate the quantity general chart, parameter a constitution, report to the police a window, history trend and register a window etc. boundary but.In the system total diagram, circulate the personnel can keep watch on signals, such as all movement appearances, equipments trouble and liquid which control an equipments and discharge...etc..Operate a personnel in the system the cent the diagram can carry on a single machine point to move to circulate an operation to all control equipmentses, become the set automatically circulate operation or the whole factorieses full-automatic operation combine surveillance.In the meantime place of honor machine 2 and do a plait distance a machine.Medium control room to establish another an inset type emulation to hold, is been one control by the place of honor machine, in order to keep the craft process of the view manifestation whole factory and main parameter value.
1. 2 The PLC stand
According to wastewater treatment of two part, the spot the long range of the equipments the control output and the spot the signal collect to control a station completion from two PLC wood ground.PLC1 native control station control the space grid, sewage promote a pump house, Pu spirit to sink sand pond's etc. to prepare a processing part.The PLC2 native control station controls dirty mire to dehydrate, press to filter machine etc. department..PLC3 native control station control SBR living creature processing part.Moreover, the on the spot native control station is each to establish an operation terminal to establish each, be responsible for at native to establish each control on the scene.(automatic control, order to move a control)
The spot is each the physical parameter that the supervision order and include water level, temperature, discharge and turn soon, electric current's etc. imitate quantity, from to in response to of an appearance spread a feeling machine or change to send to a machine examination to come out and change into the electric current signal of the 4~20 mA, through shield inside the PLC that the electric cable sends to each statures system, from the PLC picks up a people through various mold piece sample telecommunication number.Same, imitate quantity control the signal send to performance organization by the 4~20 mA electric current form after being output by the PLC, control performance organization of action.
The Modicon Quantum series PLC of Schneider company is satisfy liberal of, according to standard of network conjunction and the spot total line conjunction etc. application the technique provided various network a choice, support Modbus,
Mod-bus Plus(MB+), the long range I/0, TCP/IP etc. network conjunction, have stronger and vivid.Therefore, the wastewater treatment is convenient to arrive of the PLC choose the series of Modicon Ouantum of use Schneider.
1. 3 Correspondences
MB+agreement is the Modicon company release of an open type of the adoption IEEE802. 4 correspond by letter 5 agreements the spot total line of card agreement.MB+the network together other networks compare to have a set of net simple, the investment be little, network speed quick, correspondence the stability strong etc. characteristics, it make calculator, controller and other data sources through an usage double wring line or fiber optic cable Be a body to together carry on correspondence at the whole network top.But the CPU mold piece of the Modicon Quantum series PLC imply MB+correspondence, therefore correspond by letter a network to choose to use MB+network.Medium control two machine, two control stations with native PLC of room to pass MB+the network link together.The PLC CPU mold piece passes MB+correspondence and two machines carry on data commutation and collect the place of honor supervision various operation instruction of the system and the spot the examination signal and data, through analysis handle, pass exportation mold piece to control object output control signal;In the meantime, the PLC passes MB+net upward the machine return to various data, place of honor machine logarithms according to carry on an operation processing, show various signal and print various statement.
2 The design of PLC control program
The system has four kinds of control methods:The native hand moves a control, single set equipments point moves a control, become a set, the equipments automatically controls, the whole factory equipments full-automatic control.Two kinds of ex- with general methods at establish each adjust to try or maintain usage, the system is mainly circulate with full-automatic control.Under this kind of way, all each kind of equipmentses from PLC according to in advance draw up of procedure auto control, don't need to operate a personnel an intervention.Various spot data spreads a highest machine through a PLC, come out in the place of honor on board description and make the craft, equipments movement of whole factorieses get an overall control.
The living creature processing part of the PLC3 station control is the whole
wastewater treatment of key part, be limited by space, only with the PLC3 stand of program design for example.
2.1 Process of control
The PLC3 stationses were use to control to get into Pu spirit from sewage, the pond is everywhere sewage run off Pu after manage spirit the whole process of the pond.Include turn of sequence and time- switch moderate breezes machine of control various valve, pump, breeze machine to soon regulate etc. in this process.The Pu spirit pond is the core of wastewater treatment to construct a thing, sewage is to come and go through a microbial living creature oxygenation in the pond in addition to organic matter, the processing effect of content to sewage of the oxygen in water is to go to a pass important.Request according to the SBR craft, the deliquescence oxygen in the Pu spirit pond content usually controls within the scope of 1~3 mgs/L and annoy a stage end to fuse an oxygen content in the Pu should be not over the 2 mgs/L.Contain the oxygen once measured low or lead Gao, all will influence a fluid matter quantity.Handle 4 sets of the 10 ×104 t the SBR of 8 pond modes to respond pond to the day, each one responds that the pond go together with a pedestal from change Pin machine control of breeze machine, used for annoying pond Pu spirit to by turn provide oxygen toward two Pus.Establish 4 pieces of deliquescence oxygen test instruments in the different location of each Pu spirit pond, measure contain of sewage amount of oxygen in pond, the PLC separates a 5 mins to examine a deliquescence oxygen in a Pu spirit pond value each time, according to fuse oxygen of average value to control breeze machine to turn soon.If fuse oxygen low limit at the bottom of the enactment, the frequency modulation breeze machine turns to soon increase 5%;If fuse oxygen Gao while set upper limit, the frequency modulation breeze machine turns to soon lower 5%.So, carried out Pu spirit pond to provide automatically regulate of the amount of oxygen, since avoided unnecessary energy loss, again excellent turned movement craft.
2. 2 The design of PLC program
The adoptive plait distance software is a Concept 2. 2 XLs.Concept is according to under the Windows of the PLC plait distance tool, have good customer's interface, and have on-line follow and off-line imitate true function.The control procedure of PLC3 stationses is divided into five procedure mold piece.
(1)Public mold pieces of procedure use-include a beginning to start to turn part, hour cent second etc. ask pulse unit, SBR to respond a period enactment, fuse oxygen enactment...etc..
(2)Order control mold pieces of the switch quantity -the coordination control report to the police of circulate and related breakdown of equipmentses, such as each valve, pump and breeze machine...etc.. The enter of SBR pond spirit valve, enter water valve, reflux pump, surplus dirty mire pump from PLC according to the craft of the wastewater treatment period time segment control, water valve from PLC according to craft time and super voice liquid the measured value of the instrument to control.
(3)Protection mold pieces of the off-power-system power failure after, the PLC saves all appearance locks and make after treating to add an electricity PLC
instauration keep of the appearance continue to circulate.
(4)Mold pieces of correspondences -use to complete PLC and various data transmission of place of honor machine.
(5)Fuse an oxygen value to automatically regulate a mold piece-according to fuse an oxygen value to regulate breeze machine to turn soon and report to the police of related breakdown.The target which regulates to turn soon promises the be worth of deliquescence oxygen as 2 mgs/L in the whole Pu spirit period.Adoptive control strategy is as follows:The Pu spirit period beginning, the breeze machine at top speed movement attains a 2 mgs/L in shorterly of the hour ask by making deliquescence oxygen and take 5 mins as a period to examine deliquescence oxygen to be worth in the meantime.When fuse an oxygen value big at the 2 mgs/L, the breeze machine turns to soon descend 5%;When fuse an oxygen value small at the 2 mgs/L, the breeze machine turns to soon rise 5%.If the breeze machine turns to soon rise to allow of tallest turn soon, fuse an oxygen value return small then maintain tallest to turn soon at the 2 mgs/L.This kind of circumstance may annoy the last phase of period to appear in the Pu, but also will not clearly influence wastewater treatment quality.
Supervise and control an exportation electric current of change the Pin machine value at any time in the Pu the spirit of the whole period, make it not exceed change the sum of Pin machine settle a value.If meet a surprised circumstance to make to output electric current exceed when the sum settle value, immediately lower breeze machine to turn soon.If the breeze machine turns to soon decline to allow of lowest turn soon, output electric current to return exceed the sum settle a value, then stop breeze machine and send out to report to the police signal in the meantime Along with automatic control technical development, the UNITANK craft more and more gets extensively applied.Regard experience as principle currently, use DO, time, discharge as a craft control parameter, adjust the Pu spirit circulate of machine and line up mire the etc. lack accurate mathematics model to carry out the automatic control of higher layer of SBR method for time.Someone once put forward took the COD or the do as parameter of misty control of thought.The research direction of the automatic control of SBR method mainly is to look for several control parameters from now on, since can reflect into water of fluid matter water quantity variety and reaction process in of decline a solution circumstance, and then can do for the calculator control parameter.
The PLC gathers in proper order control and process to control at the integral whole and have dependable sex Gao, usage convenience, vivid, set net simple of the characteristics be the emollient tool of the small scale industrial automation in the realization.In the wastewater treatment, according to PLC control system at solid sex, credibility, accurate sex etc. dint a but satisfied a design a request, promised wastewater treatment of smoothly progress.
Because of Internet fast development, hope can come to visit to ask wastewater treatment factory through an Internet of from control system, the Internet which needed to input user's name and password and then can carry out long range came to carried on a control to the equipments of whole factorieses.Transport the sewage data of wastewater treatment factory to the national environmental protection bureau
through an Internet in the meantime city environmental protection bureau perhaps, for the purpose of the Bu class management of section to wastewater treatment factory.
非洲生物工程卷。7（15），第2621至2629年2008年8月4https://www.doczj.com/doc/c210513866.html,/AJB ISSN 1684-5315 2008学术期刊约旦污水处理厂处理性能及水回用的适宜性 无论是在城市还是农村环境，水资源的更有效地利用都有一个增长的趋势。在约旦，水的需求增加，水资源短缺，导致人们对废水回用产生了兴趣。在这项工作中，分别测定四个废水处理厂的水质特点，并对废水特性进行了评估。在选定的污水处理厂中测量其进出水水质的生化需氧量，化学需氧量，总悬浮固体，总溶解固体，氨氮，和溶解氧。经过处理后的出水水质与约旦的标准进行了比较。结果表明：在约旦城市废水中的生化需氧量，化学需氧量，总悬浮固体，NH4等污染物的浓度很高，所以它是一个较大的浪费。评估了四个污水处理厂的性能，常规和改良活性污泥表现出良好的性能，而低水质则是通过稳定塘产生的。活性污泥污水处理厂的出水水质符合约旦标准。为了防止其对人类健康和环境的影响，在重复使用前，二级出水需要进行深度处理。 关键词：废水，处理厂，水回用，废水特点，废水处理，约旦 前言 约旦人口迅速增加，在1950年到2006年从58万增长到560万。这一增长导致每年提高 3.1％的增长速度，并且从1948年巴勒斯坦连续移民，90年代从1967年科威特开始移民（统计处2006年）。约旦多年来一直面临着水资源短缺的问题，提高水资源的利用效率作为其努力的重要组成部分，从而来处理水资源短缺的问题。总平均降水总量约为8.5 × 109立方米/年，但这一数量的92％是通过蒸发损失掉的（铝Zboon，2002）。耗水量的增加，是人口增长和发展项目的必然结果，而水资源的有效利用却是年复一年的被限制。在2000年，每年的需水量，估计为1100万立方米，而从各种渠道的可供水量（地表水和地下水）却小于850 万立方米，这表明了250万立方米的缺水问题。这种水资源的短缺同时也影响了个人消费。例如，在1998年耗水量约为160m3/capita/y，预计在2020年将下降到90m3/capita/y，这是一个非常低的比较对于人均消费水平在1000立方米/年（铝Zboon，2002）城市农业需水量占总用水量的73％，而22％的水是用于国内需求，只有5％是用于工业部门（WAJ，2006）。 这种水资源的需求增加与限制相结合导致水资源的可利用量的发展。目前，世界各地的废水资源的再利用促进了废水有限水资源和
控制系统基础论文中英文资料外文翻译文献 文献翻译 原文： Numerical Control One of the most fundamental concepts in the area of advanced manufacturing technologies is numerical control (NC).Prior to the advent of NC, all machine tools were manual operated and controlled. Among the many limitations associated with manual control machine tools, perhaps none is more prominent than the limitation of operator skills. With manual control, the quality of the product is directly related to and limited to the skills of the operator . Numerical control represents the first major step away from human control of machine tools. Numerical control means the control of machine tools and other manufacturing systems though the use of prerecorded, written symbolic instructions. Rather than operating a machine tool, an NC technician writes a program that issues operational instructions to the machine tool, For a machine tool to be numerically controlled , it must be interfaced with a device for accepting and decoding the p2ogrammed instructions, known as a reader. Numerical control was developed to overcome the limitation of human operator , and it has done so . Numerical control machines are more accurate than manually operated machines , they can produce parts more uniformly , they are faster, and the long-run tooling costs are lower . The development of NC led to the development of several other innovations in manufacturing technology: 1.Electrical discharge machining. https://www.doczj.com/doc/c210513866.html,ser cutting. 3.Electron beam welding.
CHANGZHOU INSTITUTE OF TECHNOLOGY 毕 业 设 计 说 明 书 题目： 基于PLC 的污水处理系统的设计 SJ005-1
常州工学院电子信息与电气工程学院毕业设计说明书二级学院：电子信息与电气工程学院 专业：自动化班级： 学生姓名：学号： 指导教师：职称： 评阅教师：职称： 2013年9 月
摘要 目前，我国大多数污水处理控制系统自动化水平不高、安全性低、管理不当，效率普遍低于世界标准。中国污水处理自控系统相对落后，污水处理成本居高不下，污水厂排放的处理过的污水的水质不稳定，所以如何建立有效的自控系统，优化运行效果，减少运行费用，具有重要意义。 本文介绍了工厂污水处理的基本工艺和流程，并通过研究设计一套基于PLC控制的污水处理系统。文章首先介绍了基于PLC污水处理控制系统的工艺及相关流程，控制系统硬件结构及设计、工作原理以及设计PLC控制系统的基本原则和步骤，来说明PLC在污水处理过程中的应用。本系统设计了格栅池，调节池，反应池和除盐池，通过除盐池的最后的浓度检测保证了污水的盐浓度的达标排放。 然而本系统也存在一定的缺陷，整个系统的设计偏于简单，最后对于污水中的微生物的排放也没有详细的检测。这就需要在以后的设计中不断改善。 关键词：污水处理； PLC；工艺流程
Abstract Currently, the majority of our sewage treatment control system automation level is not high, low security, mismanagement, efficiency is generally lower than the world standards. China is relatively backward automatic control system of sewage treatment, sewage treatment and the high cost of wastewater treatment plant discharge of the treated effluent quality is unstable, so how to establish an effective automatic control system to optimize operating results, reduce operating costs, has important significance. This article describes the basic process of sewage treatment plants and processes, and through the research and design of a PLC-based control of sewage treatment systems. The article first introduces the PLC-based control system for wastewater treatment technology and related processes, control system hardware architecture and design, operating principles and design of the basic principles of PLC control system and steps to illustrate PLC in the application of the sewage treatment process. The system was designed grille pool, regulation pool, in addition to the reaction tank and Yanchi, Yanchi through except final concentration detection ensures the salt concentration of sewage discharge standards. However, the present system, there are some flaws, overall system design are somewhat simpler, and finally for the microorganisms in wastewater discharge there was no detailed testing. This requires continuous improvement in the design of the future. Keywords: sewage treatment; PLC; process
污水处理英文翻译解析 河流污水处理的相关论述 1 前言 随着工业化和城市化的发展，水环境污染、水资源紧缺日益严重，水污染控制、水环境保护已刻不容缓。我国现在新建城市或城区采用雨污分流制，但老城市或老城区大多仍然是雨污合流的排水体制。许多合流污水是直接排放到水体。而将旧合流制改为分流制，受现状条件限制大许多。老城区建成年代较长，地下管线基本成型，地面建筑拥挤，路面狭窄，旧合流制改分流制难度较大。合流污水的一大特点是旱季和雨季的水质、水量变化大，雨季污水 BOD 浓度低，不利于生化处理。国家提出 2010 的我国城市污水处理率要求达到 40%, 因此研究有效的合流污水处理方法对加快城市污水处理步伐具有重要的意义。本文针对合流污水处理的有关情况，谈一些个人看法。 2 污水处理工艺要求 我国目前不少城市，新城区与老城区并存，合流制与分流制并存。因此，新建或扩建的污水处理厂，在满足城市总体规划和排水规划需要的同时，还应能达到如下要求: 1. 具备接纳旧城区合流污水的能力，具有较强的适应冲击负荷的能力。污水处理厂污水来源包括两部分，一是新城区分流污水，二是老城区合流污水。与合流污水相比，分流污水水质、水量变化幅度小得多，对污水处理厂调节缓冲的要求小得多。对于合流污 水，降雨前期因雨水冲刷街区，合流污水较脏，但水量相对较小，降雨后期水量较大，但污水中有机物浓度相对较小。因此，降雨前期合流污水，可考虑与分流污水一起经预处理后进入污水处理构筑物。降雨后期合流污水，除一部
分与分流污水一起经污水预处理构筑物进入污水处理构筑物外，另一部分可考虑通过雨污溢流构筑物进入雨污溢流沉定池后排入附近水体。为了对进入污水处理构筑物的合流污水高峰流量、水质波动进行缓冲调节，污水处理构筑物前端可设缓冲调节池以均衡水质、储存水量。 2. 具有可靠的 BOD、 COD、 SS 去除功能及氮磷去除功能，保证最终出水水质稳定。通常情况下，城市污水中难降解有机物较少， BOD、 COD 去除比较容易实现，而氮磷去除则较复杂。我国现行的污水排放标准对污水处理厂出水氮磷指标有严格的要求，故城市污水处理都必须达到氮磷的有效去除。在现行城市污水脱氮除磷工艺中， A2/0 采用较为广泛。针对 A2/0 工艺存在的问题目前出现了许多改进工艺，每种工艺又都存在各自的特点和局限。由于合流污水引起的水质、水量波动较大，对污水厂各处理单元产生冲击，为了适应受纳水体的要求，为使 BOD、COD 等指标进一步降低，进一步去除污水中的细菌及氮、磷等植物性营养物质，在污水厂与受纳水体之间可设氧化塘。 3. 具有灵活多变的运行方式，可根据收集的污水量、进水水质以及季节变化调整运行方式。常规 A2/0 工艺，很难做到灵活方便地调整运行方式。但 A2/0工艺从构成原理上讲，是在曝气段前 加厌氧段和缺氧段。这一原理用于氧化沟技术，便可形成各种适应不同水质、水量、季节变化的运行方式。污水厂可根据实际情况设两个以上的氧化沟，每个沟设一定数量的水力推进器，池底均匀分布微孔爆气器。通过调整氧化沟污水进水管阀门、曝气器的开及关的区域、内回流比大小、污泥回流比大小及水力推进器运行个数，便可形成串联、并联等若干种运行方式。每种运行方式具有各自区域大小不同的厌氧段、缺氮段、曝气段。当旱季污水量小则采用串联运行方式，雨季污水量大，则采用并联运行方式。夏季温度高，硝化反应速度快，则采用具有较小曝气区域、较小硝化段的运行方式，相应反硝化区域
毕业设计(论文)外文资料翻译 学院：机械工程学院 专业：机械设计制造及其自动化 姓名： 学号：XXXXXXXXXX 外文出处：《Computational Intelligence and (用外文写)Design》 附件： 1.外文资料翻译译文；2.外文原文。 注：请将该封面与附件装订成册。
附件1：外文资料翻译译文 基于微型计算机的步进电机控制系统设计 孟天星余兰兰 山东理工大学电子与电气工程学院 山东省淄博市 摘要 本文详细地介绍了一种以AT89C51为核心的步进电机控制系统。该系统设计包括硬件设计、软件设计和电路设计。电路设计模块包括键盘输入模块、LED显示模块、发光二极管状态显示和报警模块。按键可以输入设定步进电机的启停、转速、转向,改变转速、转向等的状态参数。通过键盘输入的状态参数来控制步进电机的步进位置和步进速度进而驱动负载执行预订的工作。运用显示电路来显示步进电机的输入数据和运行状态。AT89C51单片机通过指令系统和编译程序来执行软件部分。通过反馈检测模块，该系统可以很好地完成上述功能。 关键词：步进电机，AT89C51单片机，驱动器，速度控制 1概述 步进电机因为具有较高的精度而被广泛地应用于运动控制系统，例如机器人、打印机、软盘驱动机、绘图仪、机械式阀体等等。过去传统的步进电机控制电路和驱动电路设计方法通常都极为复杂，由成本很高而且实用性很差的电器元件组成。结合微型计算机技术和软件编程技术的设计方法成功地避免了设计大量复杂的电路，降低了使用元件的成本，使步进电机的应用更广泛更灵活。本文步进电机控制系统是基于AT89C51单片机进行设计的，它具有电路简单、结构紧凑的特点，能进行加减速，转向和角度控制。它仅仅需要修改控制程序就可以对各种不同型号的步进电机进行控制而不需要改变硬件电路，所以它具有很广泛的应用领域。 2设计方案 该系统以AT89C51单片机为核心来控制步进电机。电路设计包括键盘输入电路、LED显示电路、发光二极管显示电路和报警电路，系统原理框图如图1所示。 At89c51单片机的P2口输出控制步进电机速度的时钟脉冲信号和控制步进电机运转方向的高低电平。通过定时程序和延时程序可以控制步进电机的速度和在某一
J I A N G S U U N I V E R S I T Y 可编程控制器课程设计 小型污水处理控制系统 学院：电气信息工程 班级：农业电气1101 姓名学号：马舒童 学号： 3110506015 指导教师：刁晓燕
目录 一、小型污水处理控制系统设计要求 1．技术要求 (1) 2．动力设备 (2) 3．设计要求 (2) 二、小型污水处理控制系统程序电路图 1. 程序流程图 (3) 2. 主电路设计 (4) 3. 交流控制电路设计 (4) 三、小型污水处理控制系统硬件软件设计 1. 可编程控制器控制电路设计 (5) 2. 输入输出口分配 (6) 3. 可编程控制器控制程序设计 (8) 4. 梯形图 (9) 5.出现问题及改进方式 (15) 6. 心得 (15) 四、参考文献
一、小型污水处理控制系统设计要求 1．技术要求 SBR废水处理技术是一种高效废水回用的处理技术，采用优势菌技术对校园生活污水进行处理，经过处理后的中水可以用来浇灌绿地、花木、冲洗厕所及车辆等，从而达到节约水资源的目的。 SBR废水处理系统方案要充分考虑现实生活中校园生活区较为狭小的特点，力求达到设备体积小，性能稳定，工程投资少的目的。废水处理过程中环境温度对菌群代谢产生的作用直接影响废水处理效果，因此采用地埋式砖混结构处理池以降低温度对处理效果的影响。同时，SBR废水处理技术工艺参数变化大，硬件设计选型与设备调试比较复杂，采用先进的PLC控制技术可以提高SBR废水处理的效率，方便操作和使用。 SBR废水处理系统分别由污水处理池、清水池、中水水箱、电控箱以及水泵、罗茨风机、电动阀门和电磁阀等部分组成，在污水处理池、清水池、中水水箱中分别设置液位开关，用以检测水池与水箱中的水位。SBR废水处理系统示意图如图1所示。 图1 SBR废水处理系统示意图 污水处理的第一阶段：当污水池中的水位处于低水位或无水状态时，电动阀会自动开起纳入污水。当污水池纳入的污水至正常高水位时，电动阀自动关闭，污水池中污水呈微氧和厌氧状态。 污水处理的第二阶段：采用能降解大分子污染物的曝气法，可使污水脱色、除臭、平衡菌群的pH值并对污染物进行高效除污，即好氧处理过程。整个好氧
附录Ⅰ： Wastewater Biological Treatment Processes The objective of wastewater treatment is to reduce the concentration of specific pollutants to the level at which the discharge of the effluent will not adversely affect the environment or pose a health threat. Moreover , reduction of these constituents need only be to some required level. For any given wastewater in a specific location , the degree and type of treatment are variables that require engineering decisions . often the degree of treatment depends on the assimilative capacity of the receiving water . DO sag curves can indicate how much BOD must be removed from wastewater so that the DO of receiving water is not depressed too far . The amount of BOD that must be removed is an effluent standard and dictates in large part the type of wastewater treatment required . To facilitate the discussion of wastewater , assume a “ typical wastewater ”and assume further that the effluent from this wastewater treatment must meet the following effluent standards : BOD≤15mg/L SS≤15mg/L P≤1mg/L Additional effluent standard could have been established , but for illustrative purposes we consider only these three . The treatment system selected to achieve these effluent standards includes 1. Primary treatment : physical processes that nonhomogenizable solids and homogenize the remaining effluent . 2. Secondary treatment : biological process that remove most of the biochemical demand for oxyen . 3. Tertiary treatment : physical , biological , and chemical processes to remove nutrients like phosphorus and inorganic pollutants , to deodorize and decolorize effluent water , and to carry out further oxidation .
译文 流体传动及控制技术已经成为工业自动化的重要技术，是机电一体化技术的核心组成之一。而电液比例控制是该门技术中最具生命力的一个分支。比例元件对介质清洁度要求不高，价廉，所提供的静、动态响应能够满足大部分工业领域的使用要求，在某些方面已经毫不逊色于伺服阀。比例控制技术具有广阔的工业应用前景。但目前在实际工程应用中使用电液比例阀构建闭环控制系统的还不多，其设计理论不够完善，有待进一步的探索，因此，对这种比例闭环控制系统的研究有重要的理论价值和实践意义。本论文以铜电解自动生产线中的主要设备——铣耳机作为研究对象，在分析铣耳机组各构成部件的基础上，首先重点分析了铣耳机的关键零件——铣刀的几何参数、结构及切削性能，并进行了实验。用电液比例方向节流阀、减压阀、直流直线测速传感器等元件设计了电液比例闭环速度控制系统，对铣耳机纵向进给装置的速度进行控制。论文对多个液压阀的复合作用作了理论上的深入分析，着重建立了带压差补偿型的电液比例闭环速度控制系统的数学模型，利用计算机工程软件，研究分析了系统及各个组成环节的静、动态性能，设计了合理的校正器，使设计系统性能更好地满足实际生产需要 水池拖车是做船舶性能试验的基本设备,其作用是拖曳船模或其他模型在试验水池中作匀速运动,以测量速度稳定后的船舶性能相关参数,达到预报和验证船型设计优劣的目的。由于拖车稳速精度直接影响到模型运动速度和试验结果的精度,因而必须配有高精度和抗扰性能良好的车速控制系统,以保证拖车运动的稳速精度。本文完成了对试验水池拖车全数字直流调速控制系统的设计和实现。本文对试验水池拖车工作原理进行了详细的介绍和分析,结合该控制系统性能指标要求,确定采用四台直流电机作为四台车轮的驱动电机。设计了电流环、转速环双闭环的直流调速控制方案,并且采用转矩主从控制模式有效的解决了拖车上四台直流驱动电机理论上的速度同步和负载平衡等问题。由于拖车要经常在轨道上做反复运动,拖动系统必须要采用可逆调速系统,论文中重点研究了逻辑无环流可逆调速系统。大型直流电机调速系统一般采用晶闸管整流技术来实现,本文给出了晶闸管整流装置和直流电机的数学模型,根据此模型分别完成了电流坏和转速环的设计和分析验证。针对该系统中的非线性、时变性和外界扰动等因素,本文将模糊控制和PI控制相结合,设计了模糊自整定PI控制器,并给出了模糊控制的查询表。本文在系统基本构成及工程实现中,介绍了西门子公司生产的SIMOREGDC Master 6RA70全数字直流调速装置,并设计了该调速装置的启动操作步骤及参数设置。完成了该系统的远程监控功能设计,大大方便和简化了对试验水池拖车的控制。对全数字直流调速控制系统进行了EMC设计,提高了系统的抗干扰能力。本文最后通过数字仿真得到了该系统在常规PI控制器和模糊自整定PI控制器下的控制效果,并给出了系统在现场调试运行时的试验结果波形。经过一段时间的试运行工作证明该系统工作良好,达到了预期的设计目的。 提升装置在工业中应用极为普遍,其动力机构多采用电液比例阀或电液伺服阀控制液压马达或液压缸,以阀控马达或阀控缸来实现上升、下降以及速度控制。电液比例控制和电液伺服控制投资成本较高,维护要求高,且提升过程中存在速度误差及抖动现象,影响了正常生产。为满足生产要求,提高生产效率,需要研究一种新的控制方法来解决这些不足。随着科学技术的飞速发展,计算机技术在液压领域中的应用促进了电液数字控制技术的产生和发展,也使液压元件的数字化成为液压技术发展的必然趋势。本文以铅电解残阳极洗涤生产线中的提升装置为研究
(文档含英文原文和中文翻译) 中英文资料对照外文翻译 Catalytic strategies for industrial water re-use Abstract The use of catalytic processes in pollution abatement and resource recovery is widespread and of significant economic importance [R.J. Farrauto, C.H. Bartholomew, Fundamentals of Industrial Catalytic Processes, Blackie Academic and Professional,1997.]. For water recovery and re-use chemo-catalysis is only just starting to make an impact although bio-catalysis is well established [J.N. Horan, BiologicalWastewater Treatment Systems; Theory and Operation, Chichester, Wiley,
1990.]. This paper will discuss some of the principles behind developing chemo-catalytic processes for water re-use. Within this context oxidative catalytic chemistry has many opportunities to underpin the development of successful processes and many emerging technologies based on this chemistry can be considered . Keywords: COD removal; Catalytic oxidation; Industrial water treatment 1.Introduction Industrial water re-use in Europe has not yet started on the large scale. However, with potential long term changes in European weather and the need for more water abstraction from boreholes and rivers, the availability of water at low prices will become increasingly rare. As water prices rise there will come a point when technologies that exist now (or are being developed) will make water recycle and re-use a viable commercial operation. As that future approaches, it is worth stating the most important fact about wastewater improvement–avoid it completely if at all possible! It is best to consider water not as a naturally available cheap solvent but rather, difficult to purify, easily contaminated material that if allowed into the environment will permeate all parts of the biosphere. A pollutant is just a material in the wrong place and therefore design your process to keep the material where it should be –contained and safe. Avoidance and then minimisation are the two first steps in looking at any pollutant removal problem. Of course avoidance may not be an option on an existing plant where any changes may have large consequences for plant items if major flowsheet revision were required. Also avoidance may mean simply transferring the issue from the aqueous phase to the gas phase. There are advantages and disadvantages to both water and gas pollutant abatement. However, it must be remembered that gas phase organic pollutant removal (VOC combustion etc.,) is much more advanced than the equivalent water COD removal and therefore worth consideration [1]. Because these aspects cannot be over-emphasised，a third step would be to visit the first two steps again. Clean-up is expensive, recycle and re-use even if you have a cost effective process is still more capital equipment that will lower your return on assets and make the process less financially attractive. At present the best technology for water recycle is membrane based. This is the only technology that will produce a sufficiently clean permeate for chemical process use. However, the technology cannot be used in isolation and in many (all) cases will require filtration upstream and a technique for handling the downstream retentate containing the pollutants. Thus, hybrid technologies are required that together can handle the all aspects of the water improvement process[6,7,8]. Hence the general rules for wastewater improvement are: 1. Avoid if possible, consider all possible ways to minimise.
英文原文 Introductions to Control Systems Automatic control has played a vital role in the advancement of engineering and science. In addition to its extreme importance in space-vehicle, missile-guidance, and aircraft-piloting systems, etc, automatic control has become an important and integral part of modern manufacturing and industrial processes. For example, automatic control is essential in such industrial operations as controlling pressure, temperature, humidity, viscosity, and flow in the process industries; tooling, handling, and assembling mechanical parts in the manufacturing industries, among many others. Since advances in the theory and practice of automatic control provide means for attaining optimal performance of dynamic systems, improve the quality and lower the cost of production, expand the production rate, relieve the drudgery of many routine, repetitive manual operations etc, most engineers and scientists must now have a good understanding of this field. The first significant work in automatic control was James Watt’s centrifugal governor for the speed control of a steam engine in the eighteenth century. Other significant works in the early stages of development of control theory were due to Minorsky, Hazen, and Nyquist, among many others. In 1922 Minorsky worked on automatic controllers for steering ships and showed how stability could be determined by the differential equations describing the system. In 1934 Hazen, who introduced the term “ervomechanisms”for position control systems, discussed design of relay servomechanisms capable of closely following a changing input. During the decade of the 1940’s, frequency-response methods made it possible for engineers to design linear feedback control systems that satisfied performance requirements. From the end of the 1940’s to early 1950’s, the root-locus method in control system design was fully developed. The frequency-response and the root-locus methods, which are the
东北大学秦皇岛分校控制工程学院自动控制系统课程设计基于PLC的污水处理系统设计 专业名称自动化 班级学号5090309 学生姓名李伟 指导教师高原 设计时间2013.7.8~2013.7.19
绪论 随着我国经济的快速发展，人民生活水平逐步提高，随之带来一系列的环境问题，特别是水环境的污染问题。我国政府对水污染的重视程度正在逐步提高，目前我国对大中城市的生活污水和工业污水己采取了一定的治理措旌，但中小城镇污水的处理情况不容乐观。全国许多小城镇没有污水处理设施，这不仅污染了当地水环境，影响了居民的身体健康，而且严重阻碍了经济的发展。为此，改善水环境，保护我国紧缺的水资源，成为刻不容缓的事情。 序批式活性污泥法(Sequencing Batch Reactors，简称SBR)符合中小城市(镇)污水处理的基本要求，其运行条件与中小城市(镇)污水的基本特征接近。SBR工艺集调节、初沉、曝气、二沉等过程于一池，按不同的时间顺序进行不同的操作，所有过程都在一个池体内进行，不需另建二沉池，也不需专用的回流污泥泵房，使水处理工艺简洁易行，构筑物占地少，布局紧凑合理，节省投资。SBR工艺抗冲击负荷能力较强，有较好的脱氮除磷效果，是一种先进的污水处理系统。SBR 工艺的这些优越性表现了其强大的生命力与广阔的应用前景。同时，SBR法本身也有一些缺点，主要表现为操作比较复杂，对自动化控制的要去较高。所以设计一套稳定可靠，节能，低成本的控制系统是十分必要的。 可编程控制器是专为工业环境下应用而设计，它采用可编制程序的存贮器，用来在其内部存贮执行逻辑运算、顺序控制、定时、计数和算术运算等操作的指令，并通过数字式、模拟式的输入输出，控制各类型的机械或生产过程。是在继电器控制和计算机控制的基础上开发出来的，并逐步发展成以微处理器为核心，把自动化技术、计算机技术、通讯技术融为一体的新型工业自动控制装置。PLC具有可靠性高、使用方便、编程简单、体积小、重量轻等特点。目前，全世界PLC 生产厂家约为200家，生产300多个品种。作为控制装置，它在许多工业领域都得到广泛的应用。随着微处理器技术和现代通信技术的发展，PLC也得到了迅速发展，其技术和产品日趋完善 将PLC应用于污水处理中大大提高了自动化程度，减少了人力投入，降低了成本。 1 系统主体设计 1.1 常用的工业污水处理工艺
河流污水处理的相关论述 1 前言 随着工业化和城市化的发展，水环境污染、水资源紧缺日益严重，水污染控制、水环境保护已刻不容缓。我国现在新建城市或城区采用雨污分流制，但老城市或老城区大多仍然是雨污合流的排水体制。许多合流污水是直接排放到水体。而将旧合流制改为分流制，受现状条件限制大许多。老城区建成年代较长，地下管线基本成型，地面建筑拥挤，路面狭窄，旧合流制改分流制难度较大。合流污水的一大特点是旱季和雨季的水质、水量变化大，雨季污水ＢＯＤ浓度低，不利于生化处理。国家提出2010 的我国城市污水处理率要求达到4０%，因此研究有效的合流污水处理方法对加快城市污水处理步伐具有重要的意义。本文针对合流污水处理的有关情况，谈一些个人看法。 2污水处理工艺要求 我国目前不少城市，新城区与老城区并存, 合流制与分流制并存。因此，新建或扩建的污水处理厂,在满足城市总体规划和排水规划需要的同时, 还应能达到如下要求: 1. 具备接纳旧城区合流污水的能力，具有较强的适应冲击负荷的能力。污水处理厂污水来源包括两部分，一是新城区分流污水，二是老城区合流污水。与合流污水相比,分流污水水质、水量变化幅度小得多，对污水处理厂调节缓冲的要求小得多。对于合流
污水，降雨前期因雨水冲刷街区,合流污水较脏, 但水量相对较小, 降雨后期水量较大，但污水中有机物浓度相对较小。因此, 降雨前期合流污水,可考虑与分流污水一起经预处理后进入污水处理构筑物。降雨后期合流污水，除一部分与分流污水一起经污水预处理构筑物进入污水处理构筑物外, 另一部分可考虑通过雨污溢流构筑物进入雨污溢流沉定池后排入附近水体。为了对进入污水处理构筑物的合流污水高峰流量、水质波动进行缓冲调节，污水处理构筑物前端可设缓冲调节池以均衡水质、储存水量。 2. 具有可靠的BOD、COD、ＳS 去除功能及氮磷去除功能, 保证最终出水水质稳定。通常情况下, 城市污水中难降解有机物较少，BOD、ＣOD 去除比较容易实现,而氮磷去除则较复杂。我国现行的污水排放标准对污水处理厂出水氮磷指标有严格的要求，故城市污水处理都必须达到氮磷的有效去除。在现行城市污水脱氮除磷工艺中，Ａ２／０采用较为广泛。针对Ａ2/0工艺存在的问题目前出现了许多改进工艺，每种工艺又都存在各自的特点和局限。由于合流污水引起的水质、水量波动较大，对污水厂各处理单元产生冲击，为了适应受纳水体的要求, 为使BOD、CＯD 等指标进一步降低,进一步去除污水中的细菌及氮、磷等植物性营养物质，在污水厂与受纳水体之间可设氧化塘。 ３.具有灵活多变的运行方式，可根据收集的污水量、进水水质以及季节变化调整运行方式。常规A2/０工艺,很难做到灵活方便地调整运行方式。但A2／0工艺从构成原理上讲, 是在曝