Kinetics model of aerobic phase in hybrid anoxic-oxic process

Kinetics models of COD degradation,biomass growth of the anoxic-oxic ( A/O) system as well as NH3-N degradation in aerobic phase were presented according to the mass balance theory,reaction-diffusion theory and Fick law. Then these models were testified by comparson with experimental results. It is demonstrated that the variation trends of theoretical and experimental values for COD degradation and biomass growth are similar. The deviation rate between theoretical and experimental values is always under 20% even it increases along with the fluctuation of influent organic loading. In terms of NH3-N degradation,nitrification can also be well simulated by the model as the substrates of influent are sufficient. It indicates that the model can accurately reflect the reaction in hybrid A/O process. Models presented herein provide a theoretical basis for the design, operation and control of hybrid A/O process.

Characteristics of anoxic phosphors removal in sequence batch reactor

The characteristics of anaerobic phosphorus release and anoxic phosphorus uptake were investigated in sequencing batch reactors using denitrifying phosphorus removing bacteria （DPB） sludge. The lab-scale experiments were accomplished under conditions of various nitrite concentrations （5.5, 9.5, and 15 mg/L） and mixed liquor suspended solids （MLSS） （1844, 3231, and 6730 mg/L）. The results obtained confirmed that nitrite, MLSS, and pH were key factors, which had a significant impact on anaerobic phosphorus release and anoxic phosphorus uptake in the biological phosphorous removal process. The nitrites were able to successfully act as electron acceptors for phosphorous uptake at a limited concentration between 5.5 and 9.5 mg/L. The denitrification and dephosphorous were inhibited when the nitrite concentration reached 15 mg/L. This observation indicated that the nitrite would not inhibit phosphorus uptake before it exceeded a threshold concentration. It was assumed that an increase of MLSS concentration from 1844 mg/L to 6730 mg/L led to the increase of denitrification and anoxic P-uptake rate. On the contrary, the average P-uptake/N denitrifying reduced from 2.10 to 1.57 mg PO4^3--P/mg NO3^--N. Therefore, it could be concluded that increasing MLSS of the DEPHANOX system might shorten the reaction time of phosphorus release and anoxic phosphorus uptake. However, excessive MLSS might reduce the specific denitrifying rate. Meanwhile, a rapid pH increase occurred at the beginning of the anoxic conditions as a result of denitrification and anoxic phosphate uptake. Anaerobic P release rate increased with an increase in pH. Moreover, when pH exceeded a relatively high value of 8.0, the dissolved P concentration decreased in the liquid phase, because of chemical precipitation. This observation suggested that pH should be strictly controlled below 8.0 to avoid chemical precipitation if the biological denitrifying phosphorus removal capability is to be studied accurately.

Effects of loading rate and hydraulic residence time on anoxic sulfide biooxidation

The optimal operation conditions in an anoxic sulfide oxidizing (ASO) bioreactor were investigated. The maximal removal rates for sulfide and nitrate were found to be 4.18 kg/(m3·d) and 1.73 kg/(m3·d), respectively. The volumetrical volumetric loading rates (LRs) observed through decreasing hydraulic retention time (HRT) at fixed substrate concentration are higher than those by increasing substrate concentration at fixed HRT. The sulfide oxidation in ASO reactor was partially producing both sulfate and sulfur; but the amount of sulfate produced was approximately one third that of sulfur. The process was able to tolerate high sulfide concentration, as the sulfide removal percentage always remained near 99% when influent concentration was up to 580 mg/L. It tolerated relatively lower nitrate concentration because the removal percentage dropped to 85% when influent con- centration was increased above 110 mg/L. The process can tolerate shorter HRT but careful operation is needed. Nitrate conversion was more sensitive to HRT than sulfide conversion since the process performance deteriorated abruptly when HRT was decreased from 3.12 h to 2.88 h. In order to avoid nitrite accumulation in the reactor, the influent sulfide and nitrate concentrations should be kept at 280 mg/L and 67.5 mg/L respectively. Present biotechnology is useful for removing sulfides from sewers and crude oil.

Effects of Nitrate Concentration in Main Anoxic Zone on Denitrifying Dephosphatation

The effects of nitrate concentration in the main anoxic zone on denitrifying dephosphatation capability were conducted based on modified University of Cape Town （MUCT） process. Meanwhile the relation between optimal nitrate concentration （Nopt） and influent C/N ratio was evaluated, in which the influont chemical oxygen demand （COD） concentration was stabilized at （2905：10）mg/L, the influent total phosphorus （TP） concentration was stabilized at （7.0±0. 5）mg/L. The results indicated that： （1） the nitrate concentration in the main anoxic zone had an effect on denitrifying dephosphatation capability, and the average percentages of anoxic phosphorus uptake in total phosphorus uptake （ηa） increased with nitrate cancentration increasing, i.e., increasing from 62.1% at2.0 mg/L to63.7%, 65.6%, 68.1%, and 72.3% at 2.2, 2.4, 2.6 and 2.8mg/L, respectively; （2） the Nopt as function of influent C/N ratio could be calculated by the equation： y = 0.67x^2-7.79x ＋ 22. 21; the maximum percentages of anoxic phosphorus uptake in total phosphorus uptake （ηa,max） as function of the Nopt could be calculated by the equation： y=0.77-0.33e^-（x/1.52）. The Nopt was the important control parameter that must be optimized for operation of conveational biological nutrieat removal activated sludge （BNRAS） system.

一体化厌氧-变级数缺氧/好氧循环流污水处理装置中试研究

针对现有村镇污水处理技术与装备的不足,开发出适用于村镇污水处理的新型一体化厌氧-变级数缺氧/好氧循环流(A-(AO)_n)同步脱氮除磷、沉淀分离技术与装备,以长沙某污水提升泵站沉砂池的出水作为处理对象开展中试实验。对好氧区不同溶解氧、填料填充比和分区进水条件下装置污水处理效能的变化进行研究,结果表明:当好氧区溶解氧控制在1.5~2.0 mg/L,好氧区填料填充比为30%时,装置的脱氮除磷效果最佳。在不外加碳源且不投加化学除磷药剂的条件下,出水水质优于《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级A标准。高通量测序结果显示,好氧区投加悬浮球填料后,系统中微生物总量和多样性明显提高,为系统中发生同步硝化反硝化(SND)现象创造了条件。

A novel multistage anoxic/aerobic process with sludge regeneration zone (R-MAO) for advanced nitrogen removal from domestic sewage

To achieve advanced nitrogen removal from actual municipal sewage,a novel multistage anoxic/aerobic process with sludge regeneration zone(R-MAO)was developed.The reactor was used to treat actual domestic sewage and the nitrogen removal capacity of the sludge regeneration zone(R zone)was investigated during the long-term operation.The best performance was obtained at the R zone’s Oxidation-Reduction Potential(ORP)of-50±30 mV and hydraulic residence times(HRT)of 1.2 hr.The average effluent COD,TN,NH_(4)^(+)-N and NO_(3)^(−)-N of the R-MAO process were 18.0±2.3,7.5±0.6,1.0±0.5 and 4.6±0.4 mg/L,respectively,with the corresponding removal efficiency of COD,TN and NH_(4)^(+)-N were 92.9%±1.0%,84.1%±1.5% and 97.5%±1.1%.Compared to the sole MAO system,the TN removal efficiency of the R-MAO increased by 10.1%.Besides,under the optimal conditions,the contribution of the R zone in the R-MAO that removal COD,TN,NH_(4)^(+)-N and NO_(3)^(−)-N were 0.36,0.15,0.032 and 0.82 g/day.High-throughput sequencing results showed that uncultured_bacterium_f_Burkholderiaceae(5.20%),OLB8(1.04%)and Ottowia(1.03%)played an important role in denitrification in the R zone.This study provided effective guidance for the design and operation of the R-MAO process in domestic sewage treatment.

有机负荷率对新型厌氧/好氧/缺氧工艺的影响机制探究

为了探究进水有机负荷对新型厌氧/好氧/缺氧工艺(AOA)工艺的影响,构建了新型AOA生物脱氮除磷反应器,通过控制进水COD考察了有机负荷率(OLR)对AOA工艺对污染物和营养盐去除的影响,并通过分析不同OLR工况影响下污泥特征及胞内聚合物的变化规律、微生物群落特征揭示了OLR对AOA工艺的影响机制。结果表明进水OLR由200 mg/L提高至400 mg/L,AOA工艺具有良好的去除效率,COD、TN和SOP的去除效率分别达到93.6%~96.2%、82.45%~85.1%和94.2%~98.5%。进水OLR提高了污泥往胞外聚合物含量,且显著提高了PN含量。在进水OLR为400 mg/L时,聚羟基脂肪酸酯(PHA)最大积累量为5.98 mmol/g,糖原质含量下降至6.03 mmol/g。OLR能影响AOA工艺内微生物群落结构,适量提高OLR促进了Proteobacteria和Firmicutes在污泥内的占比。研究结果为AOA工艺处理不同进水OLR的废水提供一定的数据支撑和理论依据。

低温下A/MBBR反应器快速启动的工艺参数

为了探究厌氧移动床生物膜反应器(A/MBBR)低温下影响工艺启动的因素,得到最佳的启动工况,在选用K3填料作为反应器填料和自然挂膜启动的基础上,建立了试验平台.在8~12℃的水温和不同工况水平的填充率、回流比和水力停留时间下,通过研究反应器在挂膜启动时期对污水中化学需氧量、NH 3-H和总磷的处理效果,得到了启动时期反应器在不同工况水平下的运行效果;通过研究反应器内填料上固体生物膜的质量变化,得到不同工况水平下生物膜增长速率;通过研究生物膜的产气速率,得到了不同工况水平下反应器生物膜总比呼吸速率和内源比呼吸速率.通过比较反应器运行效果和填料上生物膜的活性及呼吸速率,得到了A/MBBR反应器在8~12℃下自然挂膜启动的最佳工艺参数:填充率为40%、回流比为20%、水力停留时间为8 h时,该工况下能够兼顾污染物去除率、生物膜生长速率和生物膜活性,是最佳的启动条件,预计可缩短23%的启动时间.

AAO工艺运行过程中浮泥过多原因分析与改进

农村生活污水特点是COD浓度低、氨氮浓度高,碳氮比失衡。碳源和溶解氧是反硝化反应的关键因素,碳源不足和溶解氧控制不好,会导致缺氧池反硝化反应不完全,硝化液直接进入沉淀池,如果沉淀池排泥效果差,污泥不及时,容易发生反硝化反应,导致浮泥过多。所以需要从改善排泥和提高反硝化效果两方面去解决浮泥过多的问题。

废油漆桶清洗废水处理工程设计

根据废油漆桶清洗废水高pH值、高COD和悬浮物、可生化性较差的水质特点,设计采用加酸中和-气浮-混凝沉淀-臭氧氧化-水解酸化-缺氧-好氧-MBR组合工艺进行处理。工程运行结果表明,在进水COD、BOD_(5)、SS质量浓度分别为3750、900、450 mg/L,色度为420度时,相应出水分别为110、15、5 mg/L和15度,排水水质满足GB/T 19923—2005《城市污水再生利用工业用水水质》表1规定的洗涤用水标准。该工艺具有运行稳定,操作简单,投资及运行成本低且节约水资源等特点,实现了良好的经济效益和环境效益。

A^(2)/O工艺中溶解性有机氮的分子转化与生物有效性特征

本研究探究了厌氧/缺氧/好氧(A^(2)/O)工艺沿程溶解性有机氮(DON)浓度分布及其分子转化规律,并运用多种方法表征了各单元污水DON的生物有效性特征.结果表明,DON浓度由进水(5.3±0.3)mg/L沿厌氧池、缺氧池分别下降至(2.0±0.1),(1.8±0.2)mg/L,而有意思的是好氧池中DON浓度反而升高至(1.9±0.1)mg/L,去除率竟为(-5.6±0.6)%.傅里叶变换离子回旋共振质谱(FT-ICR-MS)分析DON分子组成特征显示,各单元活性DON分子(H/C≥1.5)占比为:厌氧池(38%)<缺氧池(41%)<好氧池(42%),表明好氧池出水DON最不稳定,易被受纳水体中藻类微生物摄取利用.同时在各单元产生的DON分子中,以蛋白/氨基糖类化合物为特征的微生物源DON占比沿程上升,由厌氧池24.77%分别上升至缺氧池29.12%、好氧池33.11%,表明微生物源DON分子是导致好氧池出水DON生物有效性升高的原因.进一步地,采用藻类生物测定厌氧池、缺氧池和好氧池沿程DON生物有效性,分别为(33.2±3.0)%、(34.9±7.0)%和(42.1±4.0)%,该结果证实了FT-ICR-MS的测定结论.此外,主成分分析表明,相比于厌氧池和缺氧池,温度对好氧池DON分子组成具有显著影响,且冬季好氧池出水DON生物有效性(49.3%±2%)高于夏季(42.1%±4.0%).因此,冬季好氧池出水DON具有更高的富营养化潜在风险.

A^(2)/O+MBR+潜流湿地在南方小流域环境综合整治中的应用

受制于该流域用地指标及用地性质的影响,结合流域环境整治的景观需求,采用了灰绿结合的A^(2)/O+MBR+潜流湿地组合工艺形式作为流域治理的水质净化处理工艺对流域收集的污水进行处理。工程运行四年来,出水主要指标稳定达到《地表水环境质量标准》(GB3838-2002)Ⅳ类水质标准(TN≤10 mg/L),其中再生水厂COD、BOD5、NH_(3)-N、TN、TP、SS平均去除率分别达到91.18%、98.27%、97.83%、62.74%、91.29%和99.04%;潜流湿地NH_(3)-N、TN、TP平均去除率分别达到38.44%、12.15%和33.04%。工程实践表明,该组合工艺不仅满足了流域水质要求、节约占地,同时也起到了很好的景观效果。

地毯厂生产废水处理站提标改造工程设计与应用

以河南某地毯厂为例,污水处理规模为100 m^(3)/d,原水化学耗氧量(COD)2500~3200 mg/L、五日生化需氧量(BOD_(5))1000~1500 mg/L、氨氮(NH_(3)-N)30~50 mg/L、总氮(TN)40~70 mg/L、固体悬浮物(SS)400~700 mg/L、色度800~1000倍,在原污水处理工艺的基础上增加缺氧处理工艺和混凝沉淀处理工艺。处理后出水水质满足《河南省黄河流域水污染物排放标准》(DB 41/2087—2021)规定限值,即COD≤40 mg/L、BOD_(5)≤10 mg/L、NH_(3)-N≤3 mg/L、TN≤12 mg/L、SS≤20 mg/L、色度≤30倍。该改造工艺运行费用低、管理简单方便、易于操作、无二次污染。

城市污水处理效率及影响因素分析

为了提高城市污水中常规污染物的处理效率,使其达到相关国家标准的排放要求,以某城市污水为研究对象,考察了三级AO处理工艺对常规污染物的处理效率,并评价了进水配比、HRT和污泥回流比对处理效率的影响。结果表明,在进水量与原工艺相同的条件下,将三级AO工艺中三段进水配比调整为2∶2∶1,HRT调整为12 h,污泥回流比调整为80%,在该工艺条件下,目标城市污水经过处理后出水端的COD、总氮、氨氮和总磷分别为27.15,9.18,0.79,0.38 mg/L,含量均能达到一级A标准要求。研究结果可为采用同类污水处理工艺的城市污水处理厂提供一定的借鉴。

缺氧分段式UCT工艺的脱氮除磷效能

在UCT工艺的基础上,提出一种新型缺氧分段式UCT工艺用于高效脱氮除磷。试验考察了新工艺对模拟生活污水的处理效果,并对各个功能单元的氮磷去除能力和微生物群落进行分析。工艺运行结果表明,CODCr、氨氮、TN和TP的平均去除率分别为95.85%、99.37%、83.12%和87.13%。通过氮磷质量平衡发现,前段缺氧池和后段缺氧池均呈现出明显的脱氮能力。同时分段式进水模式有利于系统脱氮能力的提升,从而有效降低回流至厌氧池的NO-3-N浓度,减小NO-3-N对厌氧释磷的不利影响。高通量测序结果揭示了变形菌门(Proteobacteria)和拟杆菌门(Bacteroidota)为优势菌门。在新型UCT工艺中,Candidatus_Competibacter(18.75%~26.43%)、OLB8(7.81%~12.52%)等反硝化菌为优势菌属,Tetrasphaera和Dechloromonas是主要的聚磷菌,有利于实现高效的脱氮除磷。

Effect of short-term atrazine addition on the performance of an anaerobic/anoxic/oxic process

In this study,an anaerobic/anoxic/oxic(A^(2)O)wastewater treatment process was implemented to treat domestic wastewater with short-term atrazine addition.The results provided an evaluation on the effects of an accidental pollution on the operation of a wastewater treatment plant(WWTP)in relation to Chemical Oxygen Demand(COD)and biological nutrient removal.Domestic wastewater with atrazine addition in 3 continuous days was treated when steady biological nutrient removal was achieved in the A^(2)O process.The concentrations of atrazine were 15,10,and 5 mg%L–1 on days 1,2 and 3,respectively.The results showed that atrazine addition did not affect the removal of COD.The specific NH4þoxidation rate and NO3–reduction rate decreased slightly due to the short-term atrazine addition.However,it did not affect the nitrogen removal due to the high nitrification and denitrification capacity of the system.Total nitrogen(TN)removal was steady,and more than 70%was removed during the period studied.The phosphorus removal rate was not affected by the short-term addition of atrazine under the applied experimental conditions.However,more poly-hydroxy-alkanoate(PHA)was generated and utilized during atrazine addition.The results of the oxygen uptake rate(OUR)showed that the respiration of nitrifiers decreased significantly,while the activity of carbon utilizers had no obvious change with the atrazine addition.Atrazine was not removed with the A^(2)O process,even via absorption by the activated sludge in the process of the short-term addition of atrazine.

SBR工艺交替硝化反硝化运行方式的可行性研究

将交替好氧、缺氧运行方式应用于间歇式污水处理系统(SBR工艺),分别在原水碱度充足和碱度不足情况下考察该运行方式的可行性.结果表明:原水碱度充足时,交替硝化反硝化的运行方式在处理效率上并没有体现出优势;原水碱度不足时,交替硝化反硝化与传统硝化反硝化相比,处理效率与出水水质明显提高,出水氨氮可以达到检测水平.当原水碱度的不足量低于所需碱度理论值的1 3时,采取交替硝化反硝化,无需额外补充碱度就可以达到原水碱度充足情况下的处理效率.如果原水碱度的不足量已超过1 3,采取交替硝化反硝化可最大限度节省额外投加碱度的量,降低处理成本,是一种理想的运行方式.

生物膜法A^2/O^2焦化废水处理系统缺氧反应器工艺特性

以焦化厂废水处理系统气浮设备出水为试验废水水源,在中试规模上研究了生物膜法A2/O2(厌氧/缺氧/好氧/好氧)系统中缺氧反应器的工艺特性和效果。缺氧反应器为以陶粒作填料的上流式滤池。研究结果表明,缺氧反硝化对去除焦化废水中COD有重要作用。反硝化菌可利用一些好氧微生物和厌氧微生物都难以降解的焦化废水中的有机物作碳源,反硝化反应器可去除进水中40%的COD。缺氧反硝化反应器进水碳氮质量比在5以上就可基本满足焦化废水反硝化对碳源的需求。稳定运行状况下的NO3--N容积负荷不大于0.24 kg/(m3.d)。缺氧反应器的水力停留时间不小于24 h。系统进水COD、NH3-N的质量浓度分别在1 000～2 200、200～400 mg/L范围内,对系统进水不进行稀释的条件下,水解酸化反应器HRT为20 h,缺氧反应器HRT为24 h,一级好氧反应器和二级好氧反应器HRT均为48 h,二级好氧反应器硝化液回流比为3时,生物膜法A2/O2系统处理出水的COD和NH3-N可以同时达到《污水综合排放标准》(GB8978-1996)中的一级排放标准。

A^2O工艺中反硝化除磷及过量曝气对生物除磷的影响

如何有效提高城市污水厂除磷效率一直是研究的热点,而反硝化除磷菌可以在碳源不足的条件下,通过“一碳两用”的方式同时实现反硝化脱氮和吸磷作用,是一种新型高效的技术.试验以啤酒废水为研究对象,验证了厌氧-缺氧-好氧(A2O)工艺中反硝化除磷现象的存在及其对系统脱氮除磷的影响.试验结果表明,A2O系统稳定运行时,反硝化聚磷菌在缺氧区可利用在厌氧段储存的PHB大量吸磷,同时氮也得到去除,计算表明缺氧除磷量可占厌氧总释磷量的71.3%,另外可节约曝气能耗25%.无论系统进水COD浓度从200mg.L-1变化为400mg.L-1,COD、总氮和总磷去除率总能保持较高水平,平均出水总氮和总磷浓度分别小于10mg.L-1和0.30mg.L-1.另外发现,过量曝气对系统除磷具有明显的影响,导致除磷效率降低,甚至会产生不吸磷现象,系统需要经过约一个污泥龄时间才能恢复其吸磷能力,所以应加强系统曝气的控制.

A^2O活性污泥工艺去除污水中雌激素的试验

试验研究了厌氧—缺氧—好氧(A2O)活性污泥工艺对雌二醇(E2)和乙炔雌二醇(EE2)的去除性能.基于同时去除雌激素和脱氮除磷的考虑,对A2O工艺的部分运行参数如水力停留时间、污泥龄和混合液回流比进行优化.试验结果表明,A2O工艺对污水中雌激素有较强的去除能力.在温度为20℃、污泥回流比为100%的情况下,除磷脱氮和去除雌激素最佳的工艺运行参数为:水力停留时间8h,污泥龄20d,混合液回流比300%.此时,总氮,PO43--P,COD的去除率分别达到81%,95%,84%;E2降到检测限以下,厌氧、缺氧、好氧池各段对E2的去除量分别占总去除量的72%,6%,22%;EE2的去除率大于80%,厌氧、缺氧、好氧各反应池对EE2的去除量分别占总去除量的45%,21%,34%.