A/O生物脱氮工艺内循环回流和外碳源投加综合控制的优化

为了提高A/O工艺反硝化效果,应用COST/IWA-Benchmark基准对5种内循环回流量和外碳源投加综合控制策略进行了比较.结果表明,控制策略1无论从外碳源消耗量、出水水质,还是从控制器稳定性上都是最优的控制策略,它有2个反馈环路组成,一个环路控制外碳源投加量,从而维持缺氧区出水硝酸氮浓度处于最优设定值2mg/L,另外一个环路控制内循环回流量,维持好氧区出水硝酸氮浓度(根据排放标准确定,一般为8～12mg/L).该策略在低负荷时可以高效利用缺氧区反硝化容量,而在高负荷时通过控制外碳源投量保证出水硝酸氮满足排放标准.     

前置反硝化工艺外碳源投加串级控制策略研究

反硝化反应需要以有机碳源为电子受体.由于污水厂的进水负荷时刻在变化,当进水碳氮比较低时,需要外投加碳源.为了有效地控制外碳源投加量,提出了由两个PI控制器组成的外碳源投加串级控制策略,可以控制出水硝酸氮浓度以及缺氧区末端硝酸氮浓度.由Matlab/Simulink模拟表明,该控制器具有良好的动态品质、抗冲击负荷强,可快速响应进水负荷的变化,能在降低出水硝酸氮和总氮浓度的同时,大大降低外碳源投量.     

前置反硝化脱氮系统外加碳源在线控制基础

以低碳氮比(C/N)生活污水为研究对象,对连续流前置反硝化生物脱氮系统外加碳源的控制方法进行了研究,从而能使出水硝酸盐和亚硝酸盐(NO_x-N)的浓度在满足出水水质标准的情况下,尽可能减少外加碳源的投加量.试验结果表明:总回流比大于2碳源不足时,增加总回流比并不能提高脱氮效率;总回流比一定,缺氧区出水NO_x^--N的浓度达到2mg/L左右时,即使碳源投加量成倍增加,TN的去除率提高不多.在对总回流比与投加碳源量的相互关系分析的基础上提出了外加碳源量的控制方案:通过使缺氧区出水NO_x^--N浓度维持在2mg/L左右来控制外加碳源的投加量,总回流比由进水TN及出水NO_x^--N浓度的标准值来确定.该控制方案既容易判断碳源投加的最佳点又能节省碳源的投加量,易于在污水处理实践中实现.     

改善焦化废水生物脱氮效率的研究

采用SBR反应器对焦化废水进行生物脱氮处理时，存在NO2^--N的积累现象。通过控制pH和投加碳源来改善生物脱氮效率。结果表明，把反应器内pH水平控制在7．0-7．5时，反硝化速率最大。比较了在好氧阶段2和缺氧阶段2投加甲醇对脱氮效率的影响。在没有外加碳源的情况下，SBR反应器的脱氮效率平均为78．4％，在好氧阶段2投加甲醇时，反应器的脱氮效率平均为90．2％，在缺氧阶段2投加甲醇时，反应器的脱氮效率平均93．8％。在投加甲醇后脱氮效率比没有外加碳源时有明显的提高，通过调节pH值和投加碳源可明显增加脱氮效果。     

缺氧-好氧生物脱氮工艺曝气量在线控制策略分析

曝气控制是生物脱氮工艺重要的控制变最,它决定着整个处理系统的处理效果和运行费用.应用Benchmark-BSM1平台模型对缺氧-好氧生物脱氮工艺几种典型的曝气控制策略进行了研究,结果表明,前馈-反馈曝气量控制最优,其次为反馈控制、恒DO控制和恒曝气量控制.前馈-反馈控制和恒DO控制相比较,出水氨氮浓度大约降低24%,最大出水氨氮浓度降低18%,曝气能耗降低9%,获得了曝气量最优控制方法以及在不同运行条件下应采用的曝气控制策略,为了实现缺氧-好氧生物脱氮工艺硝化反应的最优控制,应同时控制曝气量和好氧区体积.     

间歇投加碳源模式下SND的脱氮效能

采用模拟碳源偏低的城市污水,于连续曝气的SBR内,在不同间歇投加碳源的模式下,考察氮转化和DO、ORP及pH的变化规律。结果表明,随间歇投加碳源次数的增加,同步硝化反硝化(SND)的脱氮效率得到提高,DO浓度和ORP值的波动降低。由此可知,间歇多次投加碳源的运行模式是碳源偏低城市污水实现稳定而高效脱氮SND的有效控制策略。     

氧化沟工艺低氧同步脱氮启动研究

在常温条件下,采用小试Pasveer氧化沟处理低C/N实际污水,通过控制好氧区平均ρ(DO)为0.2～0.4 mg/L,保持好氧区与缺氧区体积比为1∶1,成功实现低氧脱氮过程。其中,模式1先接种好氧污泥并逐渐降低好氧区DO,然后接种缺氧污泥;模式2初始阶段保持低氧环境,并直接接种好氧和缺氧混合污泥。结果显示:两种方式均能成功启动低氧脱氮并保持较高的脱氮率;同时,当C/N值为1.94时,氨氮去除率较高;当C/N值为3.00时,总氮去除率较高,低氧低碳条件下脱氮效果较好。     

溶解氧对一体化膜泥法OCO工艺脱氮削碳的影响

以人工模拟生活污水为处理对象,研究了在不同好氧区溶解氧浓度对一体化膜泥法OCO反应器脱氮削碳的影响。结果表明:在进水COD均值为300mg/L,进水流量为20L/h时,缺氧区与混合区的DO随好氧区的DO而变;在DO为2mg/L左右时,具有较理想的脱氮削碳效果,出水氨氮、总氮和COD分别为0.5mg/L、8mg/L和12mg/L去除率分别达到99%、80%和96%;结合化学除磷,TP的去除率可达91%以上。     

Simulation studt on effects of different A/O parut o. s of oxidation ditches on nitrogen removal

采用3种不同曝气模式的模拟氧化沟分别形成2、4、7个缺氧-好氧（A/O）分区,研究了3种工况下氧化沟的脱氮方式和脱氮效果.结果表明,在好氧缺氧区体积比例相同的条件下,A/O分区越多,则好氧区平均DO浓度越小,硝化菌活性越低,在2、7个4、A/O分区的3种工况下的硝化菌活性分别为4.80、和3.73mg·g·h4.65-1-1;A/O分区少,则每一分区的缺氧段和好氧段长,进水后反硝化菌利用的有机物就多,在好氧区中的有机物就少,用于硝化的DO量多,从而硝化和脱氮效果好.试验中3种工况的总氮平均去除率分别为60.14%、47.93%、57%,出水总氮平均浓度分别为17.01、22.17和27.92mg·L-1.在氧化沟工艺中,氮的去除途径主要是缺氧反硝化及同步硝化反硝化（SND）.分区多,则主要通过同步硝化反硝化脱氮;分区少,则以缺氧反硝化脱氮为主,这是由于碳源限制致使同步硝化反硝化的脱氮效率比缺氧反硝化低.     

强化A2/O工艺反硝化除磷性能的运行控制策略

以啤酒废水为研究对象,重点考察了如何强化A2/O工艺反硝化除磷性能,从而提高营养物去除效果、并实现节能的目的.试验中建立了3种运行控制策略:(1)根据缺氧区末端出水硝酸盐的浓度控制内循环回流量;(2)调节厌氧/缺氧/好氧区体积比以减少厌氧区出水剩余COD对缺氧磷吸收的影响;(3)向缺氧区引入旁流并调节旁流比.试验结果表明,当缺氧区末端出水硝酸盐浓度控制在1～3 mg·L-1时,不仅可强化反硝化除磷效果,而且可以节省内循环所需能耗;厌氧/缺氧/好氧区最佳体积比为1/1/2;旁流的引入可以提高低C/N比条件下TN的去除,最优旁流比为0.32.     

Study of control strategy and simulation in anoxic-oxic nitrogen removal process

The control strategy and simulation of external carbon addition were specially studied in an anoxic-oxic(A/O) process with low carbon: nitrogen(C/N) domestic wastewater. The control strategy aimed to adjust the flow rate of external carbon dosage to the anoxic zone, thus the concentration of nitrate plus nitrite(NOx^- -N) in the anoxic zone was kept closed to the set point. The relationship was studied between the NOx^- -N concentration in the anoxic zone(SNo) and the dosage of external carbon, and the results showed that the removal efficiency of the total nitrogen(TN) could not be largely improved by double dosage of carbon source when SNO reached about 2 mg/L. Through keeping SNO at the level of about 2 mg/L, the demand of effluent quality could be met and the carbon dosage could be optimized. Based on the Activated Sludge Model No. 1 (ASM No. 1), a simplified mathematical model of external carbon dosage was developed, Simulation results showed that PI controller and feed-forward PI controller both had good dynamic response and steady precision. And feed-forward PI controller had better control effects due to its consideration of influent disturbances.     

Nitrogen removal influence factors in A/O process and decision trees for nitrification/denitrification system

In order to improve nitrogen removal in anoxic/oxic(NO) process effectively for treating domestic wastewaters, the influence factors, DO( dissolved oxygen), nitrate recirculation, sludge recycle, SRT( solids residence time), influent COD/TN and HRT( hydraulic retention time) were studied. Results indicated that it was possible to increase nitrogen removal by using corresponding control strategies,such as, adjusting the DO set point according “to effluent ammonia concentration; manipulating nitrate recirculation flow according to nitrate concentration at the end of anoxic zone. Based on the experiments results, a knowledge-based approach for supervision of the nitrogen removal problems was considered, and decision trees for diagnosing nitrification and denitrification problems were built and successfully applied to NO process.     

碳氮比对分段进水生物脱氮的影响

探讨了6组不同的碳氮比(C/N)对分段进水生物脱氮工艺中进水流量分配、每一段中缺氧区好氧区容积比以及脱氮效率的影响.将进水总氮浓度恒定为42mg/L(凯氏氮浓度为40mg/L),以比较出水总氮浓度.结果表明,在一定C/N条件下,通过调整进水流量分配和每一段缺氧区与好氧区容积比可达到高于95%的总氮去除率.同时污泥体积指数也会随着进水流量分配系数的升高而增大.出水总氮浓度主要是由进水流量分配所决定,每一段中缺氧区好氧区的容积比影响不大.     

Effects of La3+, Ce3+ on nitrogen removal in sequencing batch reactor

Batch experiments were conducted to study the short-term biological effects of rare earth ions (La³⁺, Ce³⁺) and their mixture on the nitrogen removal in a sequencing batch reactor (SBR). The data showed that higher NH₄ ⁺-N removal rate, total inorganic nitrogen removal efficiency, and denitrification efficiency were achieved at lower concentrations of rare earth elements (REEs) (<1 mg/L). In the first hour of the aeration stage of SBR, the presence of REEs increased the total inorganic nitrogen removal efficiency and NH₄ ⁺-N removal efficiency by 15.7% and 10%–15%, respectively. When the concentrations of REEs were higher than 1 mg/L, the total inorganic nitrogen removal efficiency decreased, and nitrate was found to accumulate in the effluent. When the concentrations of REEs was up to 50.0 mg/L, the total inorganic nitrogen removal efficiency was less than 30% of the control efficiency with a high level of nitrate. Lower concentrations of REEs were found to accelerate the nitrogen conversion and removal in SBR.     

铁炭内电解垂直流人工湿地对污水厂尾水深度脱氮效果

针对污水厂尾水总氮(TN)含量偏高、微生物可利用碳源低的问题,构建铁炭内电解垂直流人工湿地(ICIE-VFCW)装置,研究了ICIE-VFCW对尾水的处理效果,并采用紫外-可见光光谱(UV-VIS)、凝胶过滤色谱(GFC),进一步探讨了ICIEVFCW强化脱氮机制.结果表明,ICIE-VFCW可提高系统对尾水中COD的去除,出水COD可稳定在30 mg·L~(-1)以下,全年、暖季、寒季COD平均去除率较普通垂直流人工湿地分别可提高10.16%、9.81%、11.22%.系统出水TN可维持在10 mg·L~(-1)以下,全年、暖季、寒季TN平均去除率较普通垂直流人工湿地分别提高13.72%、12.90%、16.17%.经过人工湿地处理后,污水中有机物的腐殖度、芳香度及相对分子质量(Mr)均有所下降,且ICIE-VFCW中Mr下降更为明显.湿地基质掺杂铁炭可促进尾水中大分子有机物转化为小分子,为微生物提供更多可利用碳源,从而提高脱氮效率.     

厌氧膜生物反应器出水生物脱氮技术研究

为解决AnMBR（厌氧膜生物反应器）出水NH₄+脱除的问题,提出利用AnMBR出水中残余COD_Cr、溶解性CH₄以及低价态硫元素,通过构建缺氧滤池和好氧滤池进行生物异养和硫自养脱氮的方法,进一步削减AnMBR出水COD_Cr、去除溶解性CH₄、同时同步生物脱氮.结果表明:①缺氧滤池与好氧滤池经过120 d单独驯化与33 d串联驯化后,在HRT（hydraulic retention time,水力停留时间）为6 h、进水为实际AnMBR出水的工况条件下,出水ρ（TN）为17.93 mg/L,去除率为52.7%;出水ρ（NH₄+-N）为2.78 mg/L,去除率为92.3%,达到GB 18918-2002《城镇污水处理厂污染物排放标准》一级B标准.在HRT为8 h工况条件下,出水ρ（TN）为14.60 mg/L,去除率为59.0%;出水ρ（NH₄+-N）为2.22 mg/L,去除率为93.7%,达到GB 18918-2002一级A标准.②脱氮滤池中氮脱除路径主要包括残余COD_Cr异养反硝化、溶解性CH₄异养反硝化和硫自养反硝化,并通过物料衡算评价了三者对于氮脱除的贡献,在HRT为6 h的工况条件下,脱氮滤池脱氮过程中残余COD_Cr异养反硝化、溶解性CH₄异养反硝化和硫自养反硝化三者占比分别为54.1%、24.3%和21.5%;在HRT为8 h的工况条件下,脱氮滤池脱氮过程中3种途径占比分别为70.4%、13.8%和15.8%.研究显示,脱氮滤池可以实现对AnMBR出水的低耗生物脱氮以及整体水质的达标排放.      

生物膜反应器厌氧氨氧化脱氮效能研究

利用厌氧氨氧化生物膜反应器,分别研究提高基质浓度和缩短水力停留时间(HRT)对提高反应器总氮容积去除负荷的影响。实验之前总氮容积去除负荷达到2.11kgN(/m·3d),总氮去除率为87.9%。以提高基质浓度的方式经过50d的培养,总氮容积去除负荷稳定在4.0kgN(/m·3d),进水总氮浓度从300mg/L逐渐提高到700mg/L,NH4+-N、NO2--N出水浓度分别达到70mg/L和100mg/L;以缩短HRT的方式经过55d的培养,总氮容积去除负荷达到7.0kgN(/m·3d),HRT由3h缩短至0.67h,NH4+-N、NO2--N出水浓度分别达到40mg/L和60mg/L。实验结果表明随着进水基质浓度的增加水中游离氨和亚硝酸的浓度随之增加,从而抑制厌氧氨氧化菌活性,不利于反应器脱氮效能的提高。在相同总氮容积负荷下缩短HRT有利于厌氧氨氧化细菌的富集,但过短的HRT容易导致微生物流失。     

Advanced nitrogen removal using pilot-scale SBR with intelligent control system built on three layer network

Since eutrophication has become increasingly severe in China, nitrogen and phosphorous have been the concern of wastewater treatment, especially nitrogen removal. The stabilization of the intelligent control system and nitrogen removal efficiency were investigated in a pilot-scale aerobic-anoxic sequencing batch reactor (SBR) with a treatment capacity of 60 m³/d. Characteristic points on the profiles of dissolved oxygen (DO), pH, and oxidation reduction potential (ORP) could exactly reflect the process of nitrification and denitrification. Using the intelligent control system not only could save energy, but also could achieve advanced nitrogen removal. Applying the control strategy water quality of the effluent could stably meet the national first discharge standard during experiment of 10 months. Even at low temperature (t = 13°C), chemical oxygen demand (COD) and total nitrogen (TN) in the effluent were under 50 and 5 mg/L, respectively. Translated from Acta Scientise Circumstantiae, 2006, 26(5): 745–750 [译自: 环境科学学报]