Microbial Function, Enzymatic Activities and Diversity in an Anaerobic-Anoxic-Aerobic Reactor System

Enzymatic activities of beta-glucosidase (β-GLC), leucine-aminopeptidase (LAP), and alkaline phosphatase (APA), corresponding to nutrient eliminations, and the microbial community structures were analyzed in an anaerobic-anoxic-aerobic reactor system. Results showed that most activity of β-GLC (64.2 μmol/(L·h)) associated with the largest fraction of small-molecular-weight carbohydrates was found in the aerobic reactor, indicating the existence of coupled hydrolysis-uptake mechanism in the aerobic bacteria. Similar activities of LAP presented in the anoxic and aerobic environments, whose increases accompanied by increments in nitrogen uptake rates greatly accelerated the processes of aerobic nitrification and anoxic denitrification. The highest APA activity displayed in the anaerobic reactor, however, dephosphorization performance was mainly achieved under aerobic condition. Microbial community fingerprints generated by polymerase chain reaction amplification and denaturing gradient gel electrophoresis (PCR-DGGE) revealed that Proteobacterium, Actinobacterium, and Nitrospira were the predominant classes in the activated sludge and there was no evidence of community variations among each function reactor in the system with biomass recycling.

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.

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.

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.

Removal of nitrogen and phosphorus in a combined A^2/O-BAF system with a short aerobic SRT

A bench-scale anaerobic/anoxic/aerobic process-biological aerated filter （A^2/O-BAF） combined system was carded out to treat wastewater with lower C/N and C/P ratios. The A^2/O process was operated in a short aerobic sludge retention time （SRT） for organic pollutants and phosphorus removal, and denitrification. The subsequent BAF process was mainly used for nitrification. The BAF effluent was partially returned to anoxic zone of the A^2/O process to provide electron acceptors for denitrification and anoxic P uptake. This unique system formed an environment for reproducing the denitdfying phosphate-accumulating organisms （DPAOs）. The ratio of DPAOs to phosphorus accumulating organisms （PAOs） could be maintained at 28% by optimizing the organic loads in the anaerobic zone and the nitrate loads into the anoxic zone in the A^2/O process. The aerobic phosphorus over-uptake and discharge of excess activated sludge was the main mechanism of phosphorus removal in the combined system. The aerobic SRT of the A^2/O process should meet the demands for the development of aerobic PAOs and the restraint on the nitrifiers growth, and the contact time in the aerobic zone of the A^2/O process should be longer than 30 min, which ensured efficient phosphorus removal in the combined system. The adequate BAF effluent return rates should be controlled with 1--4 mg/L nitrate nitrogen in the anoxic zone effluent of A^2/O process to achieve the optimal nitrogen and phosphorus removal efficiencies.

Anaerobic degradation of xenobiotic organic contaminants(XOCs):The role of electron flow and potential enhancing strategies

In groundwater,deep soil layer,sediment,the widespread of xenobiotic organic contaminants(XOCs)have been leading to the concern of human health and eco-environment safety,which calls for a better understanding on the fate and remediation of XOCs in anoxic matrices.In the absence of oxygen,bacteria utilize various oxidized substances,e.g.nitrate,sulphate,metallic(hydr)oxides,humic substance,as terminal electron acceptors(TEAs)to fuel anaerobic XOCs degradation.Although there have been increasing anaerobic biodegradation studies focusing on species identification,degrading pathways,community dynamics,systematic reviews on the underlying mechanism of anaerobic contaminants removal from the perspective of electron flow are limited.In this review,we provide the insight on anaerobic biodegradation from electrons aspect-electron production,transport,and consumption.The mechanism of the coupling between TEAs reduction and pollutants degradation is deconstructed in the level of community,pure culture,and cellular biochemistry.Hereby,relevant strategies to promote anaerobic biodegradation are proposed for guiding to an efficient XOCs bioremediation.

Effect of Sludge Retention Time on the Fate of Proteins and Polysaccharides in AAO Process

Effect of sludge retention time( SRT) on the removal of potential and polysaccharides in an anaerobic / anoxic / aerobic( AAO) process was investigated. The Lowry method and anthrone method were used to detect proteins and polysaccharides. Total removal efficiency of proteins at SRT of 10 to 25 d in the AAO system was higher than 90%. Polysaccharides removal efficiencies were above 80% when SRT was increased from 15 to 25 d,whereas only 81% of polysaccharides was removed at SRT of 10 d. The biodegradation part of proteins and polysaccharides increased from87. 40% to 93% and from 74. 22% to 86. 94% with increasing SRTs.The ratios of polysaccharides and proteins in extracellular polymer substances( EPSs) were around 1. 5-3 in different SRTs. As SRT increasing,polysaccharides and proteins discharged with residual sludge decreased gradually. The amount of EPSs decreased with increasing SRTs.

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。

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。

生物脱氮除磷工艺厌氧/缺氧环境倒置效应

厌氧、缺氧环境是生物脱氮除磷工艺必不可少的重要组成部分，就该两种环境的先后顺序及其对工艺性能的影响进行机理研究。结果表明：常规工艺厌氧（Ａ１）／缺氧（Ａ２）／好氧（Ｏ）布置方式的合理性是值得再探讨的。把常规工艺的厌氧、缺氧环境倒置过来，即以缺氧（Ａ２）／厌氧（Ａ１）／好氧（Ｏ）方式运行可明显提高工艺的氮磷脱除效果。在同等条件下，Ａ２／Ａ１／Ｏ系统的出水Ｏｒｔｈｏ－Ｐ比常规Ａ１／Ａ２／Ｏ系统低５０％，而比反硝化速率却比后者高４０－５０％。

水解酸化/AAO工艺的同步脱氮除磷及污泥减量研究

针对传统活性污泥法脱氮除磷效率低、污泥产量高的缺点，提出了水解酸化／缺氧-厌氧-好氧（HAAO）污水、污泥一体化处理工艺，研究了该工艺去除COD、氮、磷和污泥减量的效果及其主要影响因素。试验结果表明，在进水COD为286-425mg／L、NH4^＋ -N为36-58mg／L、PO4^3- -P为4-12mg／L、总水力停留时间为11．5h及无外加碳源和碱度的条件下，系统对COD、NH4^＋ -N、TN、PO4^3- -P的去除率分别可达95％、98％、84％、87％。好氧段的DO浓度、固体停留时间（SRT）和剩余污泥回流比对系统的运行效果有重要影响。将污水和剩余污泥同时进行水解酸化，既可有效地改善污水的可生化性，提高系统对碳源的利用效率，又可实现污泥的减量化，试验条件下系统的污泥减量率达56．5％。

碳源对缺氧/厌氧/好氧工艺脱氮除磷效果的影响

通过投加有机碳源改变进水的碳氮比,考察了不同碳氮比条件下缺氧/厌氧/好氧工艺的脱氮除磷效果。结果表明:在污泥回流比为120%的条件下,当C/N值为7、C/P值为75时,缺氧/厌氧/好氧工艺对污水的脱氮除磷效果最佳,对TP、NH4+-N和TN的去除率分别可达95%以上、98%和67%。

基于数学模型的多模式AAO系统运行优化研究

构建了综合考虑出水水质、污泥产量和系统能耗的运行成本指数CPI,并利用数学模型对多模式厌氧/缺氧/好氧（AAO）系统的AAO、倒置AAO（RAAO）和缺氧/好氧（AO）3种模式进行对比优化研究.在处理成本相近的前提下,在污泥龄5-25d范围内AAO模式的污染物去除效率和聚磷菌浓度明显高于RAAO和AO模式.在运行模式筛选的基础上,通过回流比优化确定了排放标准约束下AAO工艺的达标运行区域和最佳运行工况.动态模拟结果表明,优化工况能够显著改善出水水质,出水高于一级A的时间由78.4%下降至37.7%,CPI降低3.9%.

短程硝化反硝化去除高氨氮猪场废水中的氮

对比分析了运用缺氧／好氧SBR工艺处理2种COD／N不同的废水的脱氮效果，结果表明，2种废水的脱氮主要是通过短程硝化反硝化实现的，反应器中的NH4^+-N浓度和pH值是控制亚硝酸型硝化的重要因素，经过部分厌氧消化的废水由于保持了较高的COD／N，脱氮效果明显好于完全厌氧消化废水，NH4^+-N去除率达到98％以上，但出水反硝化不完全，投加乙酸钠后出水NOx^--N由100-120mg／L减少到10-20mg／L，乙酸钠投加量以275mg／L为宜．

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.

草甘磷废水处理技术

对经电解预处理后的草甘磷废水采用选择性生物反应器 - UASB- CAAS组合工艺进行处理。试验结果表明 :当进水 COD为 2 6 5 0 0～ 30 0 0 0 mg/ L,Cl-为 5 6 78～ 7892 m g/ L 时 ,处理后出水 COD小于 15 0 mg/ L,COD平均去除率达到 99%以上 。

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。