碳源投加方式对短程反硝化性能的影响

短程反硝化是非常有前景的硝酸盐废水前处理方法,可为厌氧氨氧化提供必需的底物（NO₂^-N）,而不同碳源投加方式会影响短程反硝化的性能。在进水NO₃^-N为100 mg/L、乙酸钠为碳源、碳氮比为2的条件下,探究了不同碳源投加方式（1次投加、3次投加、6次投加）对短程反硝化氮素转化特性及反应速率的影响。结果表明,分次投加碳源可以在短时间内启动高效稳定的短程反硝化,且6次投加方式条件下短程反硝化性能最优。6次投加碳源（t=0/10/20/30/40/50 min）条件下短程反硝化出水NO₃^-N、NO₂^-N平均浓度分别为7.33、60.92 mg/L,NO₃^-N至NO₂^-N的平均转化率（NTR）为86.55%,NO₃^-N比还原速率和NO₂^-N比还原速...     

碳源对短程反硝化-厌氧氨氧化工艺效能的影响

为探究大分子有机碳源对短程反硝化-厌氧氨氧化(PD/A)系统脱氮效能的影响,通过在厌氧氨氧化(Anammox)连续流反应器中投加葡萄糖和新型组合填料快速启动生物膜-活性污泥PD/A工艺,研究了不同碳源条件(单一碳源和混合碳源)和不同COD/NO₃^--N下该工艺的脱氮性能。结果表明,以葡萄糖为唯一碳源,控制COD/NO₃^--N为4.5,在第90天成功启动PD/A系统,TN去除率达到93.89%,出水TN为6.17 mg/L,此时Anammox过程对去除TN的贡献率高达95.83%,反硝化过程的贡献率仅为4.17%;而由于短程反硝化菌对淀粉和葡萄糖混合碳源的利用率下降,在混合碳源驱动下PD/A系统的TN去除率降至90.53%(COD/NO₃^--N=5),出水TN为9.19 mg/L,且反硝化过程对去除TN的贡献率升至8.48%。微生物高通量测序结果表明,在两种碳源条件下,变形菌门均为绝对优势菌门,其相对丰度均大于50%;Candidatus＿Brocadia和...     

Cd2+胁迫对短程反硝化的影响与微生物群落变化

接种城市污水厂二沉池污泥,以乙酸钠为碳源,通过合理控制NO₃^--N浓度和COD/NO₃^--N启动短程反硝化(PD),并考察了长期投加不同Cd²⁺浓度的PD性能、胞外聚合物EPS和微生物群落变化。经过84 d的驯化成功启动PD,出水NO₂^--N浓度和亚硝酸盐积累率(NAR)均处于较高水平,其最高值分别为33.94 mg/L和81.24%,系统平均NAR为71.99%。Cd²⁺胁迫试验表明,与空白对照组S1相比,S2(2.5 mg/L)、S3(5 mg/L)和S4(10 mg/L)均呈现不同程度的短程反硝化性能恶化趋势,到第36天S2、S3和S4平均NAR分别下降了12.48%、14.59%和19.00%,但在高浓度Cd²⁺(5、10 mg/L)条件下,系统仍具有较高的NAR。重金属对微生物活性的毒性抑制导致S2的EPS含量高于S3和S4的EPS含量,EPS含量显著增加说明微生物通过分泌大量EPS来吸附Cd²⁺。微生物高通量测序表明,变形菌门、拟杆菌门和绿弯菌门居PD系统主导地位,反应器NO2^--N积累菌属Thauera的丰度表现为S2(2.13%)>S3(0.28%)>S1(0.2%)>S4(0.1%),表明10 mg/L的Cd²⁺不利于Thauera菌属生长,Cd²⁺浓度低于5 mg/L时Thauera菌属有生长的趋势。     

不同电子供体的部分自养反硝化研究进展

Anammox技术的应用因电子受体NO₂^--N难以稳定获取而受到限制，研究表明，部分自养反硝化是获取NO₂^--N积累的有效途径。分别论述了以还原态硫(S⁰、硫化物)、CH₄、H₂作为电子供体应用于自养反硝化时对NO₂^--N积累的影响因素和存在的问题，并介绍了相关微生物及反应酶，以期为自养反硝化耦合Anammox时电子供体的选择提供参考。结果表明，以还原态硫为电子供体的反硝化安全、经济，但存在二次污染的风险；以CH₄为电子供体的反硝化环保、无毒，但安全性及传质效率低；以H₂为电子供体的反硝化无二次污染，安全性及传质效率同样较低，CH₄和H₂皆可利用膜生物膜反应器(MBfR)提升传质效率。     

城镇污水处理厂外加商业碳源的选择

分别以乙酸钠、葡萄糖和白砂糖作为外加碳源,考察了其对生物处理系统反硝化脱氮效果的强化作用。结果表明,在一定条件下,三种物质对系统的反硝化能力均具有明显的强化效果,但其有效作用时间和反硝化速率有所不同,以乙酸钠为碳源时的反硝化速率约为以葡萄糖和白砂糖为碳源时的2倍,而在同等COD投加当量下的有效作用时间约为葡萄糖和白砂糖的一半。     

活性污泥内碳源含量的估测与表征方式研究

基于内源反硝化动力学,评估不同培养条件下活性污泥的内源反硝化能力,研究间接表征污泥中内碳源含量的方法,以利于实现活性污泥内碳源的充分利用.研究结果表明,当COD由100 mg/L增至400 mg/L时,培养污泥的内源反硝化速率基本从零增至15.68 mgNO3- - N/(L·h),内源反硝化能力明显增强；在试验条件下,不同污泥、不同浓度下的内源反硝化动力学均具有良好的线性度(R2＞ 0.94),在此基础上推导得到污泥内碳源含量为2.86Kt(K为污泥的比内源反硝化速率系数,t为反应时间)；根据推导公式计算的NO3- -N去除率与实测值接近.利用内源反硝化动力学间接表征内碳源含量的方法具有一定的有效性和稳定性,且可操作性强,适用于指导污水处理厂的日常运行.     

A/O SBR中同步硝化反硝化除磷颗粒污泥的富集

以聚糖菌颗粒污泥为接种污泥，在厌氧／好氧SBR中成功富集了具有同步硝化反硝化除磷效果的颗粒污泥。结果表明，培养过程中，污泥总磷含量、厌氧释磷量及磷酸盐去除率的提高表明反应器中聚磷菌逐渐替代聚糖菌成为优势菌种；培养末期颗粒污泥的粒径为600～1000μm，SVI为48mL／g，有机物主要在厌氧阶段被去除并以胞内聚合物（PHB）的形式储存，厌氧阶段对TOC的去除率为87％，对TOC的总去除率为90％，对磷酸盐的去除率为95．6％；氮的去除是在好氧条件下经同步硝化反硝化完成的，且PHB为主要的反硝化碳源，对氨氮的去除率为99．3％，对总氮的去除率为85．5％。     

丙酸/乙酸比值对反硝化除磷的影响

分别以丙酸、丙酸/乙酸(浓度比值为0.5、2)、乙酸为碳源,在SBR中采用厌氧/缺氧方式驯化富集反硝化聚磷菌(DPB),研究了丙酸/乙酸比值对反硝化除磷系统中有机物的降解、PO3-4-P的释放与吸收、NO-x-N浓度、PHB和糖原含量以及污泥中磷含量的影响.结果表明,随着丙酸/乙酸比值的提高,厌氧释磷量减少,厌氧末期的PHB含量降低,缺氧段聚磷菌的合成和代谢能力减弱,最终导致对PO3-4-P的去除率降低.因此,乙酸含量高的碳源更利于反硝化除磷的进行.     

基于水厂砂滤填料附着物的BAF启动及其硝化性能

对自来水厂砂滤池上层填料附着微生物的三组培养物进行了16S rRNA基因扩增子测序,分析其群落组成和结构差异,随后将三组培养物混合后成功启动了4个曝气生物滤池并分析各装置的硝化性能。结果表明：三组培养物仅检测出硝化螺旋菌属、亚硝化螺旋菌属和亚硝化单胞菌属三种硝化菌属;在NH₄⁺-N浓度为0.5 mg/L时,硝化螺旋菌属是唯一的高丰度硝化微生物,由于缺少氨氧化细菌的存在,推测该硝化螺旋菌属可能存在完全氨氧化菌。4个曝气生物滤池装置成功启动后,在水力停留时间为2 d的条件下,滤池对NH₄⁺-N均有较高的去除率（>98%）。以石英砂为填料的装置在连续进水的初期NO₃^--N浓度显著降低,由于进水未添加有机物且溶解氧充足,推测装置在此期间发生了好氧条件下的自养反硝化。以活性炭为填料的装置在连续进水后,不仅NH₄⁺-N去除率高,而且还对NO₃^--N有较高的去除率（>99...     

反硝化聚磷菌的分离鉴定及各单菌的反硝化吸磷特性

为了深入研究反硝化聚磷菌特性,采用平板分离技术,对实验室连续流双污泥系统缺氧反应器中的混合液分别在反硝化菌和聚磷菌培养基中进行分离培养和菌种鉴定,并对富集培养后的每株单菌分别进行反硝化吸磷效果试验,最终筛选出同时具有反硝化吸磷能力的菌种.通过长期试验,得到具有明显反硝化效果的反硝化菌6株,分别属于弧菌科(vibrionaceae)、肠杆菌科(Enterobacteriaceae)、假单胞菌属(Pseudomonas)、气单胞菌属(Aeromonas)和微球菌属(Micrococcus);聚磷菌9株,分别属于葡萄球菌属(Staphylococcus)、链球菌科(Strcptococcus)、产碱菌属(Alcaligenes)、芽孢杆菌属(Bacillus)、假单胞菌属(Pseudomonas)和肠杆菌科(Enterobacteriaceae),其中具有反硝化能力的有6株.吸磷试验发现,在分离出来的菌种中有11株菌在不同程度上具有反硝化吸磷能力.其中假单胞菌属的JB2和产碱菌属的JB3脱氮除磷效果最好,8 h后磷的去除量分别为13.76 mg.L和11.85 mg/L.从微生物学角度进一步验证了同一菌种可以独立完成反硝化吸磷的任务,同时认为反硝化吸磷菌是由具有反硝化能力的聚磷菌和具有吸磷能力的反硝化菌共同组成的.     

Accumulation of nitrous oxide in aerobic groundwaters

N₂O concentrations in the groundwaters collected in the Kanto District and Nagano Prefecture in Japan and five counties in New York State were determined. These N₂O data were obtained from the water samples from wells, springs and seepages from soils in forests and cropping fields. The N₂O concentrations in all samples greatly exceeded those of atmospheric equilibration. The average concentration of 690 nM N₂O is one order of magnitude larger than that in deep ocean. All groundwaters of the present study were aerobic with a high level of NO₃⁻, but with the absence of NO₂⁻ and NH₄⁺, and with a very low level of dissolved organic carbon. These characteristics suggest that the nitrate respiration in the aquifers is of little significance for the production of N₂O.

ΔN₂O/NO₃⁻ molar ratios in the groundwaters were between 10⁻⁴ and 10⁻² (Δ indicates the excess gas over that which would be in equilibrium). This supports the above view since the observed N₂O yield agrees with that reported for the production during an ammonia oxidation. If nitrification was indeed a major mechanism for the production of groundwater N₂O, subsequent release of N₂O from the aquifers that are polluted with nitrogen may deserve more close attention as a potential source of atmospheric N₂O via diffusion and discharge.     

深床反硝化生物滤池碳源优选研究

借助深床反硝化生物滤池对葡萄糖和乙酸钠两种碳源的挂膜及硝态氮去除性能进行了对比研究。试验结果表明,当碳氮比为3时,连续投加葡萄糖36 h以上,滤池内部开始进入缺氧环境,此时出水硝态氮浓度开始降低;而乙酸钠在碳氮比为3.2时,需连续投加碳源26 h,出水DO才开始降低到0.5 mg/L以下,此时滤池出水硝态氮浓度开始降低。当碳源均按照葡萄糖和乙酸钠的最佳碳氮比进行投加时,硝态氮最大去除率分别为82%和85%;此外,当以葡萄糖作为碳源时,反洗排水中MLSS约为乙酸钠的3倍。     

High loading denitrification by biological activated carbon process

High loading denitrification was studied using granular activated carbon (Calgon Filtrasorb 400, size: 0.8–1.4 mm) column with injecting carbon source (sucrose) only once a day. Under the condition of EBCT (empty bed contact time) = 80 min, C:N RATIO = 1.88, once per day injection mode of organic supply was able to sustain an average denitrification efficiency of 84 to 89% even with influent NO₃---N concentration of 80 mgl⁻¹. With an influent NO₃---N of 20 mgl⁻¹ and C:N ratio of 1.88, however, reduction of EBCT to 20 min resulted in very poor denitrification. In the latter case, 46% of the added carbon was lost in the effluent immediately after the injection. Short EBCT critically affected the process mainly due to insufficient adsorption rate. Microbial denitrification capability and fermentation might also limit the process. Extended organic injection is a possible option to improve the process efficiency. Occurrence of the sulfate reduction was limited in early phase of the cycle.     

Denitrification studies with glycerol as a carbon source

Based on the results of experimental work, the use of glycerol as a carbon source for denitrification is discussed. Investigations were carried out in modified UASB reactor using a mixed bacterial population in medium containing 600 mg NO₃---N and essential biogens. It was found that at the most favourable C:N RATIO = 1.0 the efficiency of denitrification depended on nitrate load as well as on cell residence time. At nitrate loads in the range 220–670 mg NO₃---Nl⁻¹ day⁻¹ (0.08–0.14 mg NO₃---N mg⁻¹ day⁻¹) nitrogen removal was 0.6–0.12 mg N mg⁻¹ day⁻¹, respectively. Denitrification unit biocenosis was composed of bacteria, fungi and protozoa. The number of denitrifying bacteria per sludge weight unit within the studied range of nitrate loads was constant and averaged 23 × 10⁷ cells mg⁻¹.     

Biological denitrification in the presence of cyanide

The influence of cyanide presence on the denitrification process using methanol, propanol, sodium acetate, glucose and acetone as the energy and carbon sources were described. It was shown that during denitrification the carbonyl compounds used as the sole energy and carbon sources for denitrifiers can form cyanohydrins with the cyanide ion. The product of cyanohydrin hydrolysis is biodegradable serving as electron donors for denitrifying bacteria. The simultaneous denitrification and cyanide removal was proved.     

Denitrification rates in relation to stream sediment characteristics

Potential rates of nitrate removal were studied in sediments from three Ontario rivers that differed in texture, organic carbon contents and other characteristics. Intact 0–5 cm depth sediment cores from 22 sites on each river were overlain with aerated 5 mg 1⁻¹ NO₃⁻-N solution and incubated in the laboratory at 21°C for 48 h. Rates of nitrate-N loss from the overlying solutions varied from 37 to 412 mg m⁻² day⁻¹ for a 24 h incubation period. The acetylene blockage technique was used with nitrate amended sediments to evaluate the relative importance of denitrification and nitrate reduction to ammonium. Denitrification accounted for 80–100% of the nitrate loss in the majority of sediment samples tested. Rates of nitrate loss for the 24 h period exhibited a highly significant positive correlation (r = 0.82–0.89) with the water-soluble carbon content of the sediments in each river. Significant relationships were also observed between nitrate loss and organic carbon, total nitrogen and sediment ammonium. A decline in nitrate loss via denitrification and increased nitrate reduction to ammonium was correlated with the organic carbon and water-soluble carbon content of the stream sediments.     

Effect of exogenous carbon sources on removal of inorganic nutrient by the nitrification-denitrification process

A bench scale study was undertaken to examine the effects of exogenous carbon substrates on the removal of inorganic nitrogen and phosphorus by a simple nitrification-denitrification process. Each plastic tank reactor was subjected to a 7-h aeration followed by a 5-h anoxic stage. Methanol, glucose and sodium acetate, at the concentrations equivalent to theoretical COD values of 100 and 200 mg O₂ l⁻¹ were used as external carbon sources and were added to the reactors prior to the anoxic stage. Effects of these additions on biological phosphate release were also investigated. The results showed that 94% of NH₄⁺-N was removed at the end of the aeration period. During the anoxic stage, reduction of nitrate to nitrogen gas was recorded and the denitrification process was significantly enhanced by the addition of organic carbon substrates. At the end of the anoxic stage, over 90% reduction was achieved in the tanks with exogenous carbon substrates while only 47% of NO₃⁻-N was removed in the control reactors. Among the three substrates, sodium acetate was the most efficient and effective source, followed by methanol and glucose. Addition of sodium acetate not only increased the amount of nitrate reduction but also enhanced the rate of N removal especially when a high dosage of sodium acetate was used. With respect to phosphorus removal, 88% ortho-P was removed after the aerobic stage. Throughout the anoxic stage, P concentration was maintained at about 2 mg l⁻¹ in both control and methanol treated reactors. However, significant increase in effluent P content was recorded in both sodium acetate and glucose treatments indicating that phosphorus was released from the bacterial cells during the anoxic stage. The amount of P-release in these two treatments was related to the concentrations of the carbon substrate used.     

Experimental and model assisted investigation of an operational strategy for the BPR under low influent concentrations

The behaviour of a pilot scale biological phosphorus removal process (BPR) of the alternating type was investigated during periods of low influent concentrations and increased hydraulic load. A process disturbance of this type result in an increase in the phosphate concentration level in the anoxic/aerobic reactors and in the plant effluent shortly after the influent wastewater returns to normal strength. The accumulation of phosphorus in the system was avoided by the addition of an external carbon source either to the influent or to the effluent from the anaerobic reactor in form of sodium acetate. With the help of such an addition, the internal carbon storage compounds could be maintained at a high level, which is shown by poly-hydroxy-alcanoates (PHA) measurements. Several levels of acetate addition were investigated experimentally in order to determine a minimal amount of internally stored carbon, which could ensure the stabilization of BPR during such dynamic influent conditions. Furthermore reduction of aeration time during periods of low influent concentrations was investigated. It was observed that BPR was stabilized by combining a reduction of aeration time with carbon source addition, which maintained the internal stored carbon at a higher level. This combined control action resulted in a desired high BPR activity when the normal strength of the influent wastewater was re-established. The failure of the BPR process was sometimes observed even when comparatively high concentrations of PHA could be detected and an identification of a minimal PHA level was not possible. During this investigation an extended version of the activated sludge model No. 2 (ASM2), which includes denitrification by phosphate accumulating organisms, is used for the detailed analysis of the experiments. The model predicted the phosphorus build-up after the process disturbance as well as the performance during the stabilized experiments. Assisted by the model, the investigations indicate that a PHA limitation is not the only factor affecting the recovery of the BPR process during periods of low influent concentrations.     

Utilisation de l''algue oocystis sp. pour le traitement tertiaire des eaux usées—I. Culture en vrac de cellules préalablement conditionnées en cyclostat

With the aim of developing an efficient and economic method for the tertiary treatment of wastewater, a two-phased culture system of Oocystis alga is presented. During the first phase, a unialgal strain grows in a cyclostat supplied with secondary effluents diluted to a low concentration (50 μM NH₄⁺, i.e. 0.7 mg N 1⁻¹) of inorganic ions. Once the equilibrium is reached (i.e. the cell population is conditioned and the nutrient concentration is zero), in a second phase, the starved cells are mixed with a secondary effluent which has a higher nutrient content (200–400 μM NH₄⁺, i.e., 2.8–5.6 mg N 1⁻¹). Ion depletion (NH₄⁺, NO₃^-, NO₂^- and PO₄^3-) follows specific kinetics; successive identifiable stages related to photoperiod lead to a complete stripping of nutrients. In addition to ion concentrations, pH and cell population were determined every 2 h during the experiment. Results and conclusions are presented.