Denitrification and Dephosphatation by Anaerobic/Anoxic Sequencing Batch Reactor

Removal of denitrifying phosphorus was verified in a laboratory anaerobic/anoxic sequencing batch reactor (A/A SBR). The results obtained demonstrated that the anaerobic/anoxic strategy can enrich the growth of denitrifying phosphorus removing bacteria (DPB) and take up phosphate under anoxic condition by using nitrate as the electron acceptor. The phosphorus removal efficiency was higher than 90% and the effluent phosphate concentration was lower than lmg·L-1 after the A/A SBR was operated in a steady-state. When the chemical oxygen demand(COD) of influent was lower than 180mg·L-1, the more COD in the influent was, the higher efficiency of phosphorus removal could be attained under anoxic condition. However, simultaneous presence of carbon and nitrate would be detrimental to denitrifying phosphorus removal. Result of influence of sludge retention time (SRT) on denitrifying phosphorus removal suggested that the decrease of SRT caused a washout of DPB and consequently the enhanced biological phosphorus     

Enhanced biological nutrient removal in modified carbon source division anaerobic anoxic oxic process with return activated sludge pre-concentration☆

A pilot-scale modified carbon source division anaerobic anoxic oxic (AAO) process with pre-concentration of returned activated sludge (RAS) was proposed in this study for the enhanced biological nutrient removal (BNR) of municipal wastewater with limited carbon source. The influent carbon source was fed in step while a novel RAS pre-concentration tank was adopted to improve BNR efficiency, and the effects of an influent carbon source distribution ratio and a RAS pre-concentration ratio were investigated. The results show that the removal efficiency of TN is mainly influenced by the carbon source distribution ratio while the TP removal relies on the RAS pre-concentration ratio. The optimum carbon source distribution ratio and RAS pre-concentration ratio are 60%and 50%, respectively, with an inner recycling ratio of 100%under the optimum steady operation of pilot test, reaching an average effluent TN concentration of 9.8 mg·L?1 with a removal efficiency of 63%and an average TP removal efficiency of 94%. The mechanism of nutrient removal is discussed and the kinetics is analyzed. The results reveal that the optimal carbon source distribution ratio provides sufficient denitrifying carbon source to each anoxic phase, reducing nitrate accumulation while the RAS pre-concentration ratio improves the condition of anaerobic zone to ensure the phosphorus release due to less nitrate in the returned sludge. Therefore, nitrifying bacteria, denitrifying bacteria and phosphorus accumulation organisms play an important role under the optimum condition, enhancing the performance of nutrient removal in this test.     

改进型分段进水厌氧/缺氧/好氧工艺强化营养物去除

In order to enhance phosphorus removal in traditional step-feed anoxic/oxic nitrogen removal process,a modified pilot-scale step-feed anaerobic/anoxic/oxic (SFA²/O) system was developed,which combined a reactor similar to UCT-type configuration and two-stage anoxic/oxic process.The simultaneous nitrogen and phosphorus removal capacities and the potential of denitrifying phosphorus removal,in particular,were investigated with four different feeding patterns using real municipal wastewater.The results showed that the feeding ratios(Q₁)in the first stage determined the nutrient removal performance in the SFA²/O system.The average phosphorus removal efficiency increased from 19.17% to 96.25% as Q₁ was gradually increased from run 1 to run 4,but the nitrogen removal efficiency exhibited a different tendency,which attained a maximum 73.61% in run 3 and then decreased to 59.62% in run 4.As a compromise between nitrogen and phosphorus removal,run 3 (Q₁=0.45Q_total) was identified as the optimal and stable case with the maximum anoxic phosphorus uptake rate of 1.58mg·(g MLSS)^-1·h^-1.The results of batch tests showed that ratio of the anoxic phosphate uptake capacity to the aerobic phosphate uptake capacity increased from 11.96% to 36.85% with the optimal influent feeding ratio to the system in run 3,which demonstrated that the denitrifying polyP accumulating organisms could be accumulated and contributed more to the total phosphorus removal by optimizing the inflow ratio distribution.However,the nitrate recirculation to anoxic zone and influent feeding ratios should be carefully controlled for carbon source saving.     

A2O工艺缺氧生物磷去除

A lab-scale anaerobic-anoxic-oxic （A^2O） process used to treat a synthetic brewage wastewater was investigated. The objectives of the study were to identify the existence of denitrifying phosphorus removing bacteria （DPB）, evaluate the contribution of DPB to biological nutrient removal and enhance the denitrifying phosphorus removal in A^2O bioreactors. Sludge analysis confirmed that the average anoxic P uptake accounted for approximately 70% the total amount of P uptake, and the ratio of anoxic P uptake rate to aerobic P uptake rate was 69%. In addition, nitrate concentration in the anoxic phase and different organic substrate introduced into the anaerobic phase had significant effect on the anoxic P uptake. Compared with conventional A^2O processes, good removal efficiencies of COD, phosphorus, ammonia and total nitrogen （92.3%, 95.5%, 96% and 79.5%, respectively） could be achieved in the anoxic P uptake system, and aeration energy consumption was saved 25%. By controlling the nitrate recirculation flow in the anoxic zone, anoxic P uptake could be enhanced, which solved the competition for organic substrates among poly-P organisms and denitrifiers successfully under the COD limiting conditions. Therefore, in wastewater treatment plants the control system should be applied according to the practical situation to optimize the operation.     

Biological Nutrient Removal in a Full Scale Anoxic/Anaerobic/Aerobic/ Pre-anoxic-MBR Plant for Low C/N Ratio Municipal Wastewater Treatment

A novel full scale modified A2O （anoxic/anaerobic/aerobic/pre-anoxic）-membrane bioreactor （MBR） plant combined with the step feed strategy was operated to improve the biological nutrient removal （BNR） from low C/N ratio municipal wastewater in Southern China. Transformation of organic carbon, nitrogen and phosphorus, and membrane fouling were investigated. Experimental results for over four months demonstrated good efficiencies for chemical oxygen demand （COD） and NH4^＋-N removal, with average values higher than 84.5%and 98.1%, re-spectively. A relatively higher total nitrogen （TN） removal efficiency （52.1%） was also obtained at low C/N ratio of 3.82, contributed by the configuration modification （anoxic zone before anaerobic zone） and the step feed with a distribution ratio of 1：1. Addition of sodium acetate into the anoxic zone as the external carbon source, with a theoretical amount of 31.3 mg COD per liter in influent, enhanced denitrification and the TN removal efficiency in-creased to 74.9%. Moreover, the total phosphate （TP） removal efficiency increased by 18.0%. It is suggested that the external carbon source is needed to improve the BNR performance in treating low C/N ratio municipal waste-water in the modified A^2O-MBR process.     

缺氧条件下活性污泥反硝化和释磷对单一碳源的竞争(英文)

In order to investigate the competition for carbon source between denitrification and phosphorus release processes,simultaneous phosphorus release and denitrification in sludge operated in anoxic,aerobic mode are investigated by varying the ratio of influent COD to nitrogenous compound concentration under anoxic condition using a lab-scale sequencing batch reactor(SBR).The results show that the nitrate reduction rate is nearly independent of the ratio of influent COD to nitrate under anoxic condition.More NOx--N in the influent leads to less 3 4PO --P release during the feeding period.However, 3 4PO--P release proceeds at a low rate simultaneously with denitrification even when the influent NOx--N concentration is as large as 20 mg·L-1and its rate is increased obviously when NOx--N is denitrified to a concentration lower than 0.5 mg·L-1.The variation of pH during anoxic period gives some information about the biochemical reactions of denitrification and3 4PO--P release.When more nitrate is present in the influent,more acetate uptake in feeding period is used for direct microorganism growth.     

耦合内置缺氧区的氧化沟系统强化脱氮除磷的研究(英文)

A novel modified pilot scale anaerobic oxidation ditch with additional internal anoxic zones was operated experimentally, aiming to study the improvement of biological nitrogen and phosphorus removal and the effect of enhanced denitrifying phosphorus removal in the process. Under all experimental conditions, the anaerobic-oxidation ditch with additional internal anoxic zones and an internal recycle ratio of 200% had the highest nutrient removal efficiency. The effluent NH4+-N, total nitrogen (TN), PO43-P and total phosphorus (TP) contents were 1.2mg·L-1 , 13mg·L-1, 0.3mg·L-1 and 0.4mg·L-1, respectively, all met the discharge standards in China. The TN and TP removal efficiencies were remarkably improved from 37% and 50% to 65% and 88% with the presence of additional internal anoxic zones and internal recycle ratio of 200%. The results indicated that additional internal anoxic zones can optimize the utilization of available carbon source from the anaerobic outflow for denitrification. It was also found that phosphorus removal via the denitrification process was stimulated in the additional internal anoxic zones, which was beneficial for biological nitrogen and phosphorus removal when treating wastewater with a limited carbon source. However, an excess internal recycle would cause nitrite to accumulate in the system. This seems to be harmful to biological phosphorus removal.     

回流污泥预浓缩强化新型氧化沟系统生物除磷的研究(英文)

A pilot-scale,pre-anoxic-anaerobic oxidation ditch was used in this study to treat municipal wastewater with limited carbon source.A novel return activated sludge(RAS) pre-concentration tank was adopted for improv-ing the phosphorus removal efficiency and the effects of RAS pre-concentration ratio were studied.Under the opti-mal operational condition,the suspended total phosphorus(STP) and the total phosphorus(TP) removal efficiencies were around 58.9% and 63.9% respectively and the effluent-P was lower than 0.8 mg·L-1.The reason is that with the optimal RAS pre-concentration ratio,nitrate is completely removed with endogenous carbon source and the secondary phosphorus release is strictly restrained in the pre-anoxic tank.Therefore,the anaerobic phosphorus release and the carbon source uptake by phosphorus accumulation organisms(PAOs) in the sludge,which are ex-tremely important to the phosphorus removal process,can be fully satisfied.Furthermore,the oxidation-reduction potential is proved to be suitable for controlling the RAS pre-concentration ratio due to influent fluctuation and varied conditions.The novel modified system is also beneficial for PAO accumulation.     

Advanced removal of organic and nitrogen from ammonium-rich landfill leachate using an anaerobic-aerobic system☆

A novel system coupling an up-flow anaerobic sludge blanket (UASB) and sequencing batch reactor (SBR) was introduced to achieve advanced removal of organic and nitrogen from ammonium-rich landfill leachate. UASB could remove 88.1%of the influent COD at a volumetric loading rate of 6.8 kg COD·m?3·d?1. Nitritation–denitritation was responsible for removing 99.8%of NH4+-N and 25%of total nitrogen in the SBR under alternating aerobic/anoxic modes. Simultaneous denitritation and methanogenesis in the UASB enhanced COD and TN removal, and replenished alkalinity consumed in nitritation. For the activated sludge of SBR, ammonia oxidizing bacteria were preponderant in nitrifying population, indicated by fluorescence in situ hybridization (FISH) anal-ysis. The Monod equation is appropriate to describe the kinetic behavior of heterotrophic denitrifying bacteria, with its kinetic parameters determined from batch experiments.     

剩余活性污泥碱性发酵液用于厌氧交替好氧-缺氧序批式反应器生物除磷脱氮的碳源的研究(英文)

Activated sludge process has been widely used to remove phosphorus and nitrogen from wastewater. However, the nitrogen and phosphorus removal is sometimes unsatisfactory due to the low influent COD. Another problem with the activated sludge process is that large amount of waste activated sludge is produced, which needs further treatment. In this study, the waste activated sludge alkaline fermentation liquid was used as the main carbon source for phosphorus and nitrogen removal under anaerobic followed by alternating aerobic-anoxic conditions, and the results were compared with those using acetic acid as the carbon source. The use of alkaline fermentation liquid not only affected the transformations of phosphorus, nitrogen, intracellular polyhydroxyalkanoates and glycogen, but also led to higher removal efficiencies for phosphorus and nitrogen compared with acetic acid. It was observed that ammonium was completely removed with either alkaline fermentation liquid or acetic acid as the carbon source. However, the former resulted in higher removal efficiencies for phosphorus (95%) and nitrogen (82%), while the latter showed lower ones (87% and 74%, respectively). The presence of a large amount of propionic acid in the alkaline fermentation liquid was one possible reason for its higher phosphorus removal efficiency. Exogenous instead of endogenous denitrification was the main pathway for nitrogen removal with the alkaline fermentation liquid as the carbon source, which was responsible for its higher nitrogen removal efficiency. It seems that the alkaline fermentation liquid can replace acetic acid as the carbon source for phosphorus and nitrogen removal in anaerobic followed by alternating aerobic-anoxic sequencing batch reactor.     

序批式反应器中反硝化除磷脱氮的研究

为了提高污水脱氮除磷的效率,研究采用序批式反应器(SBR工艺)厌氧、好氧和缺氧(AOA)的运行方式富集反硝化聚磷菌(DPB),实现同步脱氮除磷。结果表明:在好氧段投加甲醇作为碳源(25—40 mg/L)可有效抑制好氧吸磷,对硝化反应影响较小,能够在缺氧段实现同时反硝化脱氮除磷。SBR反应器稳定运行10个月,当进水NH4+-N、PO43--P分别为30,15 mg/L时,总氮(TN)和PO43--P的平均去除率分别为82.5%和92.1%。聚磷菌能够利用硝酸盐作为电子受体,DPB占总聚磷菌的比例达到44.8%。与A2O运行方式相比,AOA运行方式更有利于实现DPB的富集。     

外加碳源对AOA-SBR工艺脱氮除磷效果的影响

采用厌氧/好氧/缺氧模式运行的SBR工艺处理模拟城市污水,考察外加碳源乙酸钠和污泥水解酸化上清液对其脱氮除磷效果的影响。模拟城市污水,进水水质COD为400 mg/L、氨氮为60 mg/L、磷酸盐为7 mg/L。结果表明:不投加碳源时,系统对COD、氨氮、磷酸盐的去除率分别为90%、91%、82%;乙酸钠投加量为60 mg/L的条件下,外加乙酸钠系统对COD、氨氮、磷酸盐的去除率分别为93%、100%、100%,磷的去除主要是通过好氧聚磷作用;上清液投加量折合进水COD为30 mg/L时,外加污泥水解酸化上清液系统对COD、氨氮、磷酸盐的去除率分别为97%、99%、95%,系统中出现明显的反硝化除磷现象,反硝化除磷占24%。     

序批式活性污泥法反硝化聚磷菌的培养驯化研究

以某污水处理厂活性污泥作为种泥,采用序批式活性污泥法(SBR)进行反硝化聚磷菌(DPB)培养驯化研究。结果表明,经过厌氧-好氧,厌氧-换水-缺氧,厌氧-缺氧,厌氧-缺氧-短时曝气4个阶段培养驯化,系统出水效果良好:出水PO43--P的质量浓度稳定在0.5 mg.L-1以下,平均除磷率达96%;出水COD稳定在50 mg.L-1以下,平均去除率达77%。DPB占聚磷菌的比例约为65.02%。当投加不同含量的NO3--N时,硝酸盐的含量只影响吸磷速率而不影响吸磷量。当缺氧段DPB体内的PHB为限制因素时,缺氧吸磷过程在不同NO3--N含量下基本相同。     

反硝化除磷菌的培养及驯化

针对广州地区城市污水碳量严重偏低、碳氮磷比例失调的特点,以模拟的广州污水为处理对象,采用SBR反应器,对以硝酸盐为电子受体的反硝化除磷菌的培养及驯化进行研究。试验结果表明：反硝化除磷菌存在于传统生物除磷体系中。经过两个阶段试验的培养驯化,反硝化除磷菌在聚磷菌中的比例从29．8％上升到852％。稳定运行的反硝化除磷系统具有良好的反硝化脱氮除磷性能,系统出水磷〈1．0mg／L,COD、TN、TP的平均去除率分别为90％,82％,97％。     

流量分配比对改良A/O分段进水脱氮除磷特性的影响

采用改良A/O分段进水工艺处理我国南方低浓度、低碳氮比城市生活污水。在进水COD/TN为5.16,HRT为8.7 h,SRT为15 d,MLSS为5.66 g·L^-1,污泥回流比为75%,厌氧/缺氧/好氧体积比为4∶8∶10条件下,通过设置6种不同进水流量分配比,控制各好氧段DO为1～1.5 mg·L^-1,经过150 d的连续运行,得到系统最佳流量分配比为20%∶35%∶35%∶10%;在此工况下COD、氨氮、总氮、总磷出水水质分别为33.05 mg·L-1、0.58 mg·L^-1、9.26 mg·L^-1、0.46 mg·L^-1,出水优于国家GB 18918-2002一级A排放标准。原水COD绝大部分作为厌氧释磷和反硝化脱氮所需碳源,系统对碳源有效利用率达74%;DO和ORP 的协同控制可以作为系统厌氧放磷段的控制参数;同时亦可作为缺氧段反硝化完成和好氧段硝化完成的指示性参数。     

厌氧段HRT对A2N工艺反硝化除磷脱氮效果的影响

为了考察厌氧段水力停留时间（HRT）对A2N工艺反硝化除磷脱氮效果的影响，采用连续流双污泥反硝化除磷脱氮装置以生活污水为处理对象，研究了厌氧段在不同HRT时系统的除磷脱氮效果，以及厌氧段不同HRT对系统处理过程的影响。结果表明，厌氧段是A2N工艺实现反硝化除磷脱氮的关键阶段。当厌氧段的HRT过长时，虽然溶解性PO4^3-的总释放量增加，但是后续的缺氧吸磷量和总氮的去除量并没有相应地增加。厌氧段的HRT时间过短，反硝化聚磷菌（DPB）在此对进水中易降解COD（CODRB）吸收不完全，导致后续缺氧吸磷量下降，同时影响了系统的除磷和脱氮效果。在处理实际生活污水水质时，厌氧段的HRT为2h即可满足除磷和脱氮要求。     

Evaluation of the parameters affecting nitrogen and phosphorus removal in anaerobic/anoxic/oxic (A/A/O) biological nutrient removal systems

Considerable research has been performed on biological nutrient removal (BNR) systems which remove the problematic nutrients, nitrogen and phosphorus, that cause eutrophication. This research focussed on setting up two laboratory‐scale anaerobic/anoxic/oxic (A/A/O) systems and investigating their reliability while undergoing various parameter changes. Pump failure, in the first trial, R1, led to a decrease in pH, exposure of the sludge to relatively low nitrate concentrations and reduction of the suspended solids concentration within the system. This adversely affected the phosphorus removal efficiency. Shock loading the system with increased influent phosphate concentrations for 56 days was shown to aid remediation of the phosphorus removal efficiency to values between 65 and 70% (w/w). The second trial, R2, highlighted the presence of bacteria capable of P‐uptake under anoxic conditions (in the presence of nitrate). The characteristic anaerobic P‐release was also evident. The bacteria responsible for phosphate uptake under anoxic conditions are thought to be the denitrifying phosphate removing bacteria (DPB). However, the presence of higher nitrate concentrations retarded the P‐removal efficiency to some extent. Secondary release of P was evident in the clarifier of the A/A/O system during the R2 trial and especially during times of increased nitrate concentrations in the system. Between 20 and 40% (w/w) of the P taken up in the oxic stage of the system was released in the clarifier at various stages throughout the trial. © 2000 Society of Chemical Industry     

A_2SBR工艺反硝化除磷系统的快速启动与稳定运行

为了实现废水同时脱氮除磷的目的,采用A2SBR工艺进行了长期的实验室实验,考察反硝化除磷系统的启动与运行效果。结果表明:在进水COD质量浓度200 mg/L,磷酸盐质量浓度4—11 mg/L,缺氧段硝酸盐质量浓度从25 mg/L提高到55 mg/L的条件下,采用"厌氧(2.5 h)-沉淀排水(1 h)-缺氧(3.5 h)-沉淀排水(1 h)"的周期性运行方式,可在31 d内成功启动A2SBR反硝化除磷系统,厌氧段COD、硝态氮和磷酸盐去除效率分别为77%,90%和84.96%。稳定运行后硝态氮和磷酸盐去除效率分别达到92%和91%,COD去除率高于80%,其出水磷酸盐质量浓度接近于0,表现出良好的反硝化脱氮和除磷性能。     

反硝化除磷机理与工艺研究进展

介绍了反硝化除磷机理的研究和发展状况,通过反硝化除磷的特性分析,阐述了反硝化除磷机理.介绍了反硝化除磷工艺的发展状况,通过比较得出单污泥和双污泥系统适合市政污水、低氮源和低C/N污水的脱氮除磷工艺.