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.     

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.     

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.     

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.     

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.     

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.     

Effect of Ferric Chloride on the Properties of Biological Sludge in Co-precipitation Phosphorus Removal Process

This paper studied the effect of ferric chloride on waste sludge digestion, dewatering and sedimentation under the optimized doses in co-precipitation phosphorus removal process. The experimental results showed that the concentration of mixed liquid suspended solid (MLSS) was 2436 mg稬^-1 and 2385 mg稬^-1 in co-precipitation phosphorus removal process (CPR) and biological phosphorous removal process (BPR), respectively. The sludge reduction ratio for each process was 22.6% and 24.6% in aerobic digestion, and 27.6% and 29.9% in anaerobic digestion, respectively. Due to the addition of chemical to the end of aeration tank, the sludge content of CPR was slightly higher than that of BPR, but the sludge reduction rate for both processes had no distinct difference. The sludge volume index (SVI) and sludge specific resistance of BPR were 126 ml穏^-1 and 11.7?10¹² m穔g^-1, respectively, while those of CPR were only 98 ml穏^-1 and 7.1?10¹² m穔g^-1, indicating that CPR chemical could improve sludge settling and dewatering.     

Nitrogen removal characteristics of heterotrophic nitrification-aerobic denitrification by Alcaligenes faecalis C16

Alcaligenes faecalis C16 was found to have the ability to heterotrophically nitrify and aerobical y denitrify. In order to further understand its nitrogen removal ability and mechanism, the growth and ammonium removal response were investigated at different C/N ratios and ammonium concentrations in the medium with citrate and acetate as carbon source separately. Furthermore, experiments of nitrogen sources, production of nitrogen gas and enzyme assay were conducted. Results show that the bacterium converts NH4+-N and produces NH2OH during the growing phase and nitrite accumulation is its distinct metabolic feature. A. faecalis C16 is able to tolerate not only high ammonium concentration but also high C/N ratio, and the ammonium tolerance is associated with carbon source and C/N ratio. The nitrogen balance under different conditions shows that approximately 28%–45%of the initial ammonium is assimilated into the cells, 44%–60%is denitrified and several percent is converted to nitrification products. A. faecalis C16 cannot utilize hydroxylamine, nitrite or nitrate as the sole nitrogen source for growth. However, nitrate can be used when ammonium is simultaneously present in the medium. A possible pathway for nitrogen removal by C16 is suggested. The preliminary enzyme assay provides more evidence for this nitrogen removal pathway.     

Impacts of Power Density on Heavy Metal Release During Ultrasonic Sludge Treatment Process

The impact of ultrasonic power density on changes of heavy metals during sludge sonication was inves-tigated. Results showed that ultrasound could release heavy metals from sludge into the supernatant. There existed an effective power density range of 0.8-1.6 W·ml^-1 for the release of the total heavy metal;there was little release below 0.8 W·ml^-1 and too high power density was adverse to the release. Furthermore, sonication showed selective release of heavy metal from sludge to the supernatant;copper, cadmium and lead were not released by sonication, while arsenic and nickel were released easily and their release ratio could reach 40%. The effective energy range for each heavy metal was also different that 0.8-1.2 W·ml^-1 for arsenic, 0.5-1.6 W·ml^-1 for nickel, and 0.8-1.6 W·ml^-1 for mercury and chrome. The differences among heavy metal release during sonication might be explained by the different distribution of chemical fractions of each metal in sludge. Such selectivity could be used to control heavy metal release during sludge treatment.     

Simultaneous removal of nitrogen and phosphorus from swine wastewater in a sequencing batch biofilm reactor

In this study, the performance of a sequencing batch biofilm reactor (SBBR) for removal of nitrogen and phosphorus from swine wastewater was evaluated. The replacement rate of wastewater was set at 12.5%throughout the exper-iment. The anaerobic and aerobic times were 3 h and 7 h, respectively, and the dissolved oxygen concentration of the aerobic phase was about 3.95 mg·L?1. The SBBR process demonstrated good performance in treating swine wastewater. The percentage removal of total chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) was 98.2%, 95.7%, 95.6%, and 96.2%at effluent concentrations of COD 85.6 mg·L?1, NH4+-N 35.22 mg·L?1, TN 44.64 mg·L?1, and TP 1.13 mg·L?1, respectively. Simultaneous nitrification and denitrification phenomenon was observed. Further improvement in removal efficiency of NH4+-N and TN occurred at COD/TN ratio of 11:1, with effluent concentrations at NH4+-N 18.5 mg·L?1 and TN 34 mg·L?1, while no such improvement in COD and TP removal was found. Microbial electron microscopy analysis showed that the fil er surface was covered with a thick biofilm, forming an anaerobic–aerobic microenvironment and facilitating the removal of nitrogen, phosphorus and organic matters. A long-term experiment (15 weeks) showed that stable removal efficiency for N and P could be achieved in the SBBR system.     

多点进水改良型复合A2/O处理低C/N污水

以低C/N比城市生活污水为研究对象,重点考查了改良A²/O工艺的脱氮除磷性能。原水按一定比例分配给厌氧池和缺氧池,以合理分配厌氧释磷和缺氧反硝化所需的碳源;在好氧池和缺氧池中分别投加填料,以稳定系统的硝化和反硝化效果,提高系统的脱氮性能;厌氧池和缺氧池出水都直接进入好氧池。在进水COD/TN平均为5.54,HRT为11 h,SRT为15 d,MLSS为3000～4000 mg·L^-1,污泥回流比为50%条件下,通过三种不同进水分配比以及三种混合液回流比的对比试验研究,得到系统最佳进水分配比5:5,对分配脱氮和除磷所需碳源更加合理;而混合液回流比为200%,过高会破坏缺氧池的溶解氧环境,过低又会导致缺氧池反硝化作用不能充分发挥。在最优工况下COD、NH₃-N、TN和TP出水水质分别为29.7、0.1、11.8和0.42 mg·L^-1,平均去除率分别达到87.8%、99.7%、72.4%和91.3%,出水优于国家GB 18918-2002一级A排放标准,并且在缺氧池中发生了明显的反硝化除磷现象。     

连续流双污泥反硝化除磷工艺数学模型

污泥是典型的反硝化除磷工艺,在处理低碳源生活水方面,极具应用前景。目前有关双污泥工艺的试验研究成果较多,而在双污泥工艺相关数学模型方面研究报道较少。本文的研究目的为建立一种可模拟双污泥反应过程的数学模型。参照ASM2D等模型,对主要生化反应过程的动力学模型进行线性简化,并列出了各单元污染物的物料平衡方程组,成为双污泥工艺数学模型的核心。模型的输入量包括水水质、各反应器停留时间、厌氧池污泥浓度、硝化池污泥浓度、回流比、越流比。模型的动力学参数与化学计量学参数由一实验室双泥系统的稳定运行数据估计得出（英文摘要给出了各参数的具体值）。针对目前反硝化聚磷数学模型无法体现厌氧释磷对反硝化聚磷过程影响的问题,采用平均比污泥聚磷速率与缺氧池反应时间乘积来描述缺氧聚磷过程的线性简化模型,平均比污泥聚磷速率与厌氧释磷量及反应时间有关,因此可反映厌氧释磷过程对缺氧聚磷速率的影响。 可查比污泥反硝化聚磷速率表得出,该表反映了比污泥反硝化聚磷速率与比污泥厌氧释磷量及反应历时之间的关系,可由反硝化聚磷实验获得。在模型求解之前,因比污泥厌氧释磷量未知,所以 无法确定,故无法通过一次求解模型中的线性方程组得出模型的解,针对此种情况,采用试算法求解模型。模型通过一连续流实验室双泥系统验证,结果表明,模型对各污染物浓度及沿程变化规律的预测具有较高准确性,但模型中可能存在不同误差相抵的情况,仍需进一步验证或改进。     

并联式A~2O/MBR反硝化聚磷工艺试验研究

基于反硝化聚磷理论,结合MBR工艺的优点,在传统A2O工艺的基础上提出新型并联式同步脱氮除磷工艺。工艺解决了传统工艺中的碳源不足、硝酸盐氮供需矛盾等问题;通过省去沉淀池,节约了占地面积。针对常规城市污水,研究了不同工艺条件对处理效果的影响。结果表明,当污泥体积回流比为50%,内体积回流比为100%时具有较好的去除效果,COD、NH4+-N、TP和TN去除率分别达到了90%、99%、94.4%和67%。     

混合液回流比对A/A/O工艺反硝化除磷的影响

以生活污水培养驯化污泥的小试规模A/A/O工艺为研究对象,进行了混合液回流比为100%、200%和300%时对反硝化除磷的影响研究,并利用厌氧/缺氧批式试验方法对污泥特性进行单独考察。结果表明,随着混合液回流比的增大,缺氧除磷在系统除磷所起的作用、反硝化聚磷菌缺氧利用单位聚羟基链烷酸（PHAs）的吸磷量和反硝化数量出现先升高后下降,厌氧合成单位PHAs的释磷量和好氧利用单位PHAs的吸磷量并没有受到影响,以200%时反硝化除磷和系统脱氮除磷效果为最好,过高或过低NO₃-N浓度均会影响反硝化聚磷菌的缺氧吸磷速率和PHAs降解速率,但并没有影响其本身所固有的特性。     

反硝化除磷污泥系统驯化及其性能影响因素研究综述

传统生物脱氮除磷工艺存在碳源竞争、溶解氧需求大和菌群结构竞争等诸多问题,反硝化同步脱氮除磷能够在缺氧条件下以硝酸盐为电子受体,在脱氮的同时进行超量聚磷,实现氮磷同步去除,具有节约碳源、能源、污泥产量低等优点,符合污水处理工艺节能减排的绿色发展理念.反硝化聚磷污泥的驯化是运行反硝化同步脱氮除磷工艺的前提,文中综述了一步法...     

三污泥法处理抗生素类制药废水

为有效解决传统AAO法中存在的硝化菌、反硝化菌及聚磷菌三种细菌在污泥龄、碳源需求及回流污泥中携带的硝酸盐影响聚磷菌厌氧释放磷这三方面的矛盾，减少大量污泥回流、降低动力消耗、充分利用池容、切实提高污水处理效率，提出“三污泥”理念，对AAO进行关键性改进，改进后的缺氧池、厌氧池、好氧池等生化反应池均自带独立的泥水自动分离的装置，形成独特的三污泥系统(即纯粹的厌氧污泥、纯粹的缺氧污泥和纯粹的好氧污泥)，各池可根据运营需要各自控制污泥浓度，使各池中的活性污泥在各自最佳的环境中生长，互不干扰、相互独立，更高效发挥生物降解作用，创新性设计“改进型AAO法+生物滤池+絮凝沉淀耦合工艺”处理抗生素类制药废水，并与传统型组合技术进行比较。结果表明，进水主要污染物化学需氧量CODcr 253?581 mg/L、氨氮29.6?58.5 mg/L、全磷10.77?23.1 mg/L、设计流量30.0 L/h条件下，改进型技术取得了很好的处理效果，其CODcr、氨氮、全磷的平均去除率分别达80.2%, 73.1%, 96.1%，比改进前分别提高了6.9%, 6.1%, 3.4%，尾水CODcr、氨氮、全磷等三项指标均达到《污水综合排放标准》(GB8978-1996)的一级标准。     

低碳源条件下反硝化同步除磷脱氮的研究

对低碳源条件下反硝化同步除磷脱氮的影响因素进行了研究.结果表明,在低碳源情况下,硝基氮的消耗与磷的吸收呈线性关系,在厌氧段维持合适硝基氮与磷的质量比,可较好地实现同步去除氮磷,而污泥泥龄控制不当则影响反硝化除磷的效果.     

溶解氧浓度对连续流活性污泥工艺反硝化除磷的影响

引言 随着水体富营养化问题的日渐突出,污水处理技术逐渐从单一去除有机物为目的的阶段进入既要去除有机物又要脱氮除磷的深度处理阶段[1].     

生物膜中反硝化除磷作用的研究

分析了生物膜反硝化除磷系统在生物量,污泥龄,以及碳、氮、磷质量比方面和活性污泥法反硝化除磷系统的差异。通过试验给出了生物膜反硝化除磷系统的最佳污泥龄等运行参数,并对试验现象和结果在理论上进行了分析。试验结果表明,生物膜反硝化除磷系统的最佳水力停留时间为15 d,和活性污泥法反硝化除磷系统的最佳水力停留时间(约12 d)相差不大;生物膜反硝化除磷系统的最佳碳、氮、磷质量比为26.6∶7.67∶1,其中最佳碳、氮质量比为3.5,最佳碳、磷质量比为26.6。