不同电子受体的反硝化除磷效果对比研究

反硝化除磷作用可以明显节省脱氮除磷过程的碳源需求和能耗。为研究不同电子受体下的反硝化除磷效果,利用一体化活性污泥工艺中污泥经过厌氧释磷后在不同电子受体下进行反硝化除磷试验,结果表明NO3-—N和NO2-—N均能参与反硝化除磷过程,在NO2-—N初始浓度高达30mg/L的条件下,除磷率仍在93%以上,未对反硝化除磷过程产生毒害作用。在工程应用中应加强短程硝化反硝化与反硝化除磷作用的耦合,在提高脱氮除磷效率的同时,取得明显的节能效果。     

高浓度氨氮污水对A2/O系统的影响

就A2/O工艺处理城市污水过程中高浓度氨氮对活性污泥性能、除磷脱氮效果的影响进行了研究.结果表明:高浓度氨氮影响微生物的生长和活性污泥的沉降性能;在保持高溶解氧条件下,高浓度氨氮污水取得良好的脱氨效果,但碳源不足成为脱氮效果的影响因素;高浓度氨氮污水脱氨后产生的大量NO-3残留严重影响磷的去除.     

MSBR系统的特点及其除磷脱氮的机理分析

介绍了一种新的改良型序批式活性污泥反应器———MSBR(ModifiedSequencingBatchReactor)系统。该系统能保证连续进出水 ,使反应器始终保持在恒定水位。MSBR系统综合了以往其它除磷脱氮工艺的优点 ,保证了各类污染物质降解的最大速率环境 ,使去除有机污染物效率更高 ,除磷脱氮效果更好 ,运行更稳定。结合中试运行结果对其生物除磷脱氮机理进行了分析和讨论。     

溶解氧对低碳源污水一体化处理工艺脱氮除磷的影响

通过试验对比,研究了溶解氧对低碳源污水一体化工艺脱氮除磷效果的影响。结果表明,平均溶解氧为0.18mg/L时,系统出水可以稳定达到GB 18918—2002一级A标准,溶解氧过高或过低都会降低系统脱氮除磷效果。在平均溶解氧为0.18mg/L的工况下,系统存在反硝化吸磷、同时硝化反硝化及全程反硝化3种脱氮方式,且反硝化吸磷和同时硝化反硝化脱氮量占氮总去除量的66.7%,可以较大程度降低脱氮除磷过程所需碳源量并节省耗氧量,提高低碳源污水脱氮除磷效果。     

活性污泥法脱氮除磷工艺设计方法探讨

对活性污泥法脱氮除磷工艺的设计方法进行探讨,提出以泥龄为主进行控制,采用活性污泥数学模型与经验方法相结合,并以COD为计量单位,对不同种类有机物进行分类.简述了不同有机物测定方法和设计过程.     

A~2/O法过程控制及氮磷浓度的在线测定

Ａ２Ｏ法是目前生物脱氮除磷工艺中应用较多的一种方法。由于生物脱氮除磷工艺较之传统活性污泥法远为复杂，用传统经验方法来运行脱氮除磷的污水厂已越来越不能满足工艺过程的要求。连续地测定曝气池中的溶解氧浓度、ＮＨ＋４－Ｎ浓度、ＮＯ－３－Ｎ浓度、ＰＯ３－４－Ｐ浓度并据此调节供氧强度和内回流流量以及硝化区和反硝化区的大小从而对整个工艺过程进行控制已成为保证Ａ２Ｏ工艺良好处理效果的重要手段。本文论述了Ａ２Ｏ法基本的影响因素及其过程控制思想，对工艺过程中氮磷浓度的在线测定作了介绍，并对如何借助氮浓度的在线测定优化工艺操作作了具体说明。     

一体化Orbal氧化沟清淤大修施工实例

无锡市城北污水处理厂三期工程采用一体化奥贝尔(Orbal)氧化沟为主体的A2/O除磷脱氮工艺.介绍了一体化氧化沟在有条件放空的情况下实施清淤大修的施工实例,主要包括前期准备、放空要求、清淤方案、安全措施和实施过程等.     

投加短管填料对活性污泥工艺性能的改善

在传统活性污泥工艺中投加聚氯乙烯短管填料,研究投加短管填料对活性污泥工艺性能的影响,将该系统应用于城市污水处理试验研究,并与单一活性污泥系统进行对比研究。结果表明,投加短管填料可以改善活性污泥工艺性能,系统对有机物及氮、磷去除效果显著,可在同一反应器内实现脱氮除磷。与活性污泥系统相比,投加短管填料反应器具有较强的抗冲击负荷能力。     

活性污泥法2号模型(ASM2)简介

国际水质协会（ＩＡＷＱ）在活性污泥法１号模型（ＡＳＭ１）的基础上，经专家组多年研究，推出了活性污泥法２号模型（ＡＳＭ２）。它以矩阵形式描述活性污泥法去除水中碳、氮、磷的过程。ＡＳＭ２是除磷脱氮污水厂设计及运行控制的有效工具。     

采用两级SBR工艺优化除磷脱氮

在充分分析单级SBR工艺在生物除磷脱氮过程中存在的不足的基础上 ,提出了两种两级SBR串联运行的除磷脱氮工艺模式。通过合理控制操作过程 ,该工艺可望从根本上解决单级生物除磷脱氮系统中的泥龄问题、厌氧区的硝酸盐问题、有机物对硝化作用的抑制问题和好氧时间长能耗较高的问题等 ,从而可大大提高系统除磷脱氮效果和稳定性。模式 1工艺适用于处理BOD/TP值较高的污水 ;模式 2工艺对进水BOD/TP值没有特殊的限制。     

Biological nutrient removal in membrane bioreactors: denitrification and phosphorus removal kinetics.

The impact of including membranes for solid liquid separation on the kinetics of nitrogen and phosphorus removal was investigated. To achieve this, a membrane bioreactor (MBR) biological nutrient removal (BNR) activated sludge system was operated. From batch tests on mixed liquor drawn from the MBR BNR system, denitrification and phosphorus removal rates were delineated. Additionally the influence of the high total suspended solids concentrations present in the MBR BNR system and of the limitation of substrate concentrations on the kinetics was investigated. Moreover the ability of activated sludge in this kind of system to denitrify under anoxic conditions with simultaneous phosphate uptake was verified and quantified.The denitrification rates obtained for different mixed liquor (ML) concentrations indicate no effect of ML concentration on the specific denitrification rate. The denitrification took place at a single specific rate (K(2)) with respect to the ordinary heterotrophic organisms (OHOs, i.e. non-PAOs) active mass. Similarly, results have been obtained for the P removal process kinetics: no differences in specific rates were observed for different ML or substrate concentrations. From the P removal batch tests results it seems that the biological phosphorus removal population (PAO) consists of 2 different sets of organisms denitrifying PAO and aerobic PAO.     

A novel wastewater treatment process: simultaneous nitrification, denitrification and phosphorus removal.

Simultaneous nitrification and denitrification (SND) via the nitrite pathway and anaerobic-anoxic enhanced biological phosphorus removal (EBPR) are two processes that can significantly reduce the COD demand for nitrogen and phosphorus removal. The combination of these two processes has the potential of achieving simultaneous nitrogen and phosphorus removal with a minimal requirement for COD. A lab-scale sequencing batch reactor (SBR) was operated in alternating anaerobic-aerobic mode with a low dissolved oxygen concentration (DO, 0.5 mg/L) during the aerobic period, and was demonstrated to accomplish nitrification, denitrification and phosphorus removal. Under anaerobic conditions, COD was taken up and converted to polyhydroxyalkanoates (PHA), accompanied with phosphorus release. In the subsequent aerobic stage, PHA was oxidized and phosphorus was taken up to less than 0.5 mg/L at the end of the cycle. Ammonia was also oxidised during the aerobic period, but without accumulation of nitrite or nitrate in the system, indicating the occurrence of simultaneous nitrification and denitrification. However, off-gas analysis found that the final denitrification product was mainly nitrous oxide (N2O) not N2. Further experimental results demonstrated that nitrogen removal was via nitrite, not nitrate. These experiments also showed that denitrifying glycogen-accumulating organisms rather than denitrifying polyphosphate-accumulating organisms were responsible for the denitrification activity.     

Temperature effects on biological nutrient removal system with weak municipal wastewater

The wastewater characteristics of low organic strength coupled with low temperature would be considerable variables for design and operation of biological nutrient removal (BNR) systems. But temperature studies have mostly been focused on individual process with biological phosphorus removal, nitrification and denitrification, respectively. Overall temperature effects on BNR system may not be fully represented by sum of results of separated studies on biological nutrient removal steps. The operating result of a retrofitted full scale unit along with laboratory-scale BNR unit indicated 90% of nitrification was possible at temperature as low as 8°C. However, the denitrification was turned out to be a key step to regulate the overall nutrient removal efficiencies. When the operating temperature dropped down, a rapid decrease of phosphorus removal efficiencies was observed by the nitrate in return sludge. If nitrification was not well developed, phosphorus removal returned to the normal efficiency even at low temperature of 5°C. The phosphorus removal mechanism was not influenced at this low temperature.     

城市污水生物除磷脱氮工艺中的矛盾关系及对策

目前 ,城市污水处理厂的处理对象包括COD、BOD5、SS和氮、磷等营养物质。就氮磷脱除而言 ,一般需涉及硝化、反硝化、微生物释磷和吸磷等过程。由于各过程的要求不同 ,在同一污水处理工艺系统中就不可避免地产生了各过程间的矛盾关系。针对泥龄问题、碳源问题、硝酸盐问题、系统的硝化和反硝化容量问题、释磷吸磷的容量问题进行了探讨     

Development of sequencing batch reactor with step feed and recycle.

SBR process shows high nitrogen and phosphorus removal in countries where separated sewers are used. On the other hand, removal efficiency is low in countries where combined sewers are used though the same SBR is applied. This is because the organic concentration (as BOD), which is used as carbon source for denitrification, of combined sewers is much lower than that of separated sewers. Almost all sewers in Korea are combined, and their BOD is low by about 1/2 over the level needed for denitrification. In this study, a SBR process that can optimise organic usage by step feed and recycle is thus developed to increase the removal efficiency of nitrogen and phosphorus, and the results show that the removal rates of BOD, T-N and T-P are 95.4, 81.4 and 86.1%, respectively, though influent BOD is low.     

Behaviour of activated sludge from a system with anoxic phosphate uptake

Activated sludge from a new activated sludge modification for biological phosphorus and nitrogen removal was studied. Population dynamics and the phenomenon of anoxic phosphate uptake with simultaneous denitrification were investigated.The ability of the process to remove nutrients and to suppress filamentous bulking was studied. The course of phosphate concentrations along the tested system showed an anoxic phosphate uptake with simultaneous denitrification. The mechanism of anoxic phosphate uptake was confirmed using kinetic batch tests. © 1998 IAWQ. Published by Elsevier Science Ltd     

Alternate anoxic/aerobic operation for nitrogen removal in a membrane bioreactor for municipal wastewater treatment

A large pilot-scale membrane bioreactor (MBR) with a conventional denitrification/nitrification scheme for municipal wastewater treatment has been run for one year under two different aeration strategies in the oxidation/nitrification compartment. During the first five months air supply was provided according to the dissolved-oxygen set-point and the system run as a conventional predenitrification MBR; then, an intermittent aeration strategy based on effluent ammonia nitrogen was adopted in the aerobic compartment in order to assess the impact on process performances in terms of N and P removal, energy consumption and sludge reduction. The experimental inferences show a significant improvement of the effluent quality as COD and total nitrogen, both due to a better utilization of the denitrification potential which is a function of the available electron donor (biodegradable COD) and electron acceptor (nitric nitrogen); particularly, nitrogen removal increased from 67% to 75%. At the same time, a more effective biological phosphorus removal was observed as a consequence of better selection of denitrifying phosphorus accumulating organisms (dPAO). The longer duration of anoxic phases also reflected in a lower excess sludge production (12% decrease) compared with the standard pre-denitrification operation and in a decrease of energy consumption for oxygen supply (about 50%).     

Improvement of denitrification by denitrifying phosphorus removing bacteria using sequentially combined carbon.

The effects of sequentially combined carbon (SCC) using a symbiotic relationship of methanol and acetic acid on biological nutrient removal were investigated in both the continuous bench scale process consisting of an anoxic, an aerobic and a final settling tank and intensive batch tests. Compared to the use of respective sole carbon sources, methanol and acetic acid, the use of SCC showed superior removal efficiency of nitrogen (98.3%) and phosphorus (approximately 100%). Furthermore, the use of SCC enhanced simultaneous denitrification and phosphorus uptake by denitrifying phosphorus removal bacteria (DPB), resulting in the highest specific denitrification rate (SDNR) of 0.252 g NO3-N/g VSS/d achieved from the first anoxic zone with methanol of 30 mg COD/I. From batch tests performed under carbon limited anoxic conditions, 1 g of nitrate was used by DPB for P-uptake of 1.19 g. According to this result, 0.205 g NO3-N/g VSS/d was accomplished by normal denitrifiers using methanol, and 0.047 g NO3-N/g VSS/d was achieved by DPB. This research also demonstrated that the increase of poly-beta-hydroxybutyrate (PHB) stored by phosphorus accumulating organisms (PAOs) could be of importance in improving aerobic denitrification. The use of SCC produced the highest P-release in the anoxic zone, indicating the amount of PHB would be higher compared to the use of other sole carbons. Therefore, the SCC could be a very effective carbon source for the enhancement of aerobic denitrification as well.     

环沟型改良A~2/O工艺中试研究

环沟型改良A2/O工艺是集高效初沉发酵池、回流污泥反硝化池、厌氧池及双沟道氧化沟工艺于一体的新型污水处理工艺。对该工艺去除污染物的效果进行试验研究,结果表明,在生物系统水力停留时间不足8h的条件下,达到了较好的除磷脱氮效果,出水水质稳定达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级A标准。研究结果同时表明,该工艺具有很好的节能降耗潜力。