城市污水双泥龄复合脱氮工艺的脱氮机理分析

基于部分厌氧氨氧化的双泥龄复合脱氮工艺能实现自养脱氮和异养脱氮的耦合，在城市污水低成本高效脱氮方面表现出良好的应用潜力。为进一步探究该工艺的脱氮机理，对运行2年的中试反应器开展了脱氮途径解析与优化、主要脱氮功能菌活性测定以及微生物群落结构分析。结果表明，间歇曝气可以促进短程硝化和厌氧氨氧化过程的耦合，当曝气量为20 mL/min[DO为（0.18±0.03） mg/L]时，脱氮效率最高；厌氧氨氧化菌（AnAOB）主要分布在生物膜上，活性为44.60mg/（gVSS·d），检测到的AnAOB为Candidatus Brocadia，相对丰度为0.28%；氨氧化菌（AOB）和亚硝酸盐氧化菌（NOB）主要分布在悬浮污泥中，活性分别为61.53、86.95 mg/（gVSS·d），检测到的AOB和NOB分别为Nitrosomonas和Nitrospira，相对丰度分别为0.10%、2.10%。     

pH值对SBBR自养脱氮系统效能及功能菌数量的影响

从在不同pH值条件下稳定运行的SBBR自养脱氮反应器中分别提取活性污泥及生物膜样品的基因组DNA,通过特异引物扩增系统内亚硝化菌(AOB)、硝化菌(NOB)及厌氧氨氧化(ANAMMOX)菌的基因序列,采用荧光定量PCR技术对功能菌进行定量分析,研究pH值对系统运行效能及功能菌数量的影响。研究显示,pH值对SBBR自养脱氮系统的运行效能及三大功能菌的数量均有显著影响。在pH值=6.0的酸性条件下,AOB、NOB及ANAMMOX菌数量比其他pH值条件下的低,脱氮效果差。AOB在pH值=7.0～8.0范围内数量较多,在pH值=9.0时将受到明显抑制。在pH值=7.0～9.0的范围内,NOB数量的变化趋势没有AOB的显著。在pH值=8.0时,各功能菌的数量均达到最大值,系统构成一个和谐稳定的微生态环境,运行效能较佳,因此该值为此SBBR自养脱氮系统的最佳控制点。     

生物强化接触氧化工艺原位修复受氮素污染水体

某受氮素污染河水采用接触氧化工艺处理但效果不理想,为此,模拟该河水真实流态而构建了小试装置,通过功能菌群调查,富集、驯化培养土著氨氧化菌(AOB)和亚硝酸盐氧化菌(NOB)并持续投加至好氧段,以强化硝化菌群、提高脱氮效果。采取生物强化措施后,系统对总氮和氨氮的去除率分别提高了约26%和20%;出水中的AOB和NOB菌群数量分别增加了近103和104倍,好氧段生物膜中的AOB和NOB菌群数量均增加了近102倍。DGGE图谱分析也表明,投加高效菌剂后,系统中的微生物群落结构发生了明显变化,新增的优势微生物种群与Nitrosomonassp.和Nitrobacter sp.具有高度同源性,说明系统内去除氮素的关键微生物种群得到了增强。     

游离氨对硝化菌活性的短期抑制影响试验研究

采用SBR反应器,在不同游离氨(FA)浓度梯度结合限时曝气条件下,考察了FA对全程硝化活性污泥(CNAS)和短程硝化活性污泥(PNAS)的抑制特性。结果表明,当FA浓度介于2.5~197.2 mg/L时,CNAS和PNAS系统内均可发生较好的硝化作用,氨氧化速率(AOR)均维持在较高水平,表明氨氧化菌(AOB)活性未受到抑制。但对于CNAS系统,当FA浓度达到137.6~168.4 mg/L时,亚硝酸盐氧化菌(NOB)活性受到完全抑制。此外,CNAS和PNAS的比氨氧化速率(SAOR)与FA浓度之间总体上呈现出指数增长关系,仅在反应的初始阶段,CNAS的SAOR表现出略微降低的适应过程。相对于CNAS,PNAS具有更强的抵抗FA抑制的能力。     

单级自养脱氮反应器效能与微生物群落结构的相关性

于稳定运行但效能有明显差异的2套序批式生物膜反应器单级自养脱氮系统,研究了微生物群落结构的PCR-DGGEr、eal-time PCR等现代分子生物学特点及其运行效能与之的相关性。结果表明:运行效能好的反应器活性污泥及生物膜浓度较高,微生物群落结构差异较大,二者相似性为58.3%,溶解氧在活性污泥及生物膜内的分布特点为各类微生物及其代谢创造了良好环境,系统中好氧氨氧化菌AOB及厌氧氨氧化菌ANAMMOXz在数量上绝对占优,各类细菌的协同代谢使系统总氮去除率达到80%以上。运行效能相对较差的反应器,由于在反应器启动过程中没有将亚硝酸氧化菌NOB完全"洗脱",系统中出现NO3-积累,且系统挂膜不理想,生物膜浓度低,生物膜与活性污泥微生物群落结构相似性为100%,优势功能菌单一,从而造成运行效能较低,总氮去除率仅为20%~30%。维持SBBR自养脱氮系统微生物群落结构的稳定及平衡性,生物膜是关键性因素。     

短程硝化/厌氧氨氧化联合工艺处理含氨废水的研究

在SBR中接种普通好氧活性污泥,通过控制运行条件来实现短程硝化,同时提高厌氧生物转盘系统中厌氧氨氧化的氮负荷,使之与SBR出水中NO2--N的积累量相匹配,并将二者组合形成短程硝化/厌氧氨氧化自养脱氮工艺.处理含氨废水的试验结果表明:在SBR的进水NH4+-N为150～250 mg/L、温度为(28±2)℃、pH值为7～8、DO<1 mg/L的条件下,可实现稳定的短程硝化,NO2--N积累率达85%以上,NH4+-N负荷达0.129 kgN/(kgVSS·d),AOB和NOB的数量之比为103:1.将短程硝化出水加入NH4+-N后作为厌氧氨氧化反应器的进水,在(40±1)℃下可以达到自养脱氮的目的,对NH4+-N、NO2--N和TN的去除率分别达86%、97%和90%以上,TN容积负荷为0.488 kgN/(m3·d).     

短程硝化/厌氧氨氧化一步法自养脱氮中试研究

一步法自养脱氮工艺在高氨氮废水处理中具有运行能耗低、不需外加碳源等优点。利用总容积为50 m3的SBR反应器处理高氨氮废水,成功实现了短程硝化/厌氧氨氧化一步法自养脱氮。反应器对不同氨氮浓度(350~4 300 mg/L)的废水均表现出良好的处理效果,对氨氮与总氮的平均去除率分别达到95%和90%以上。同时,还研究了反应器运行的主要影响因素、污泥粒径分布及微生物群落结构。结果表明,系统内形成了红色的厌氧氨氧化颗粒,且颗粒的比例随运行逐渐增加;而维持合理的溶解氧和氨氮浓度是实现高负荷脱氮的关键因素。     

NAUTO~(TM)自养脱氮工艺接种启动及稳定运行控制

基于MBBR开发了一种新型全程自养脱氮工艺——NAUTO~(TM),采用其处理污泥厌氧消化脱水液,考察了启动和稳定运行效果。通过接种CANON悬浮载体来缩短NAUTO~(TM)工艺的启动时间。在接种率为10%的情况下,运行84 d后对NH_4~+ -N的去除率即可达83. 40%,总氮去除负荷超过0. 90 kg/(m~3·d)。系统稳定运行超过300 d,出水NH_4~+ -N浓度低于30 mg/L,氨氮和TN去除率分别达到95. 06%和89. 71%,TN去除负荷最高可达1. 21 kg/(m~3·d)。对悬浮载体的高通量测序结果显示,NAUTO~(TM)工艺启动成功后,氨氧化菌(AOB)和厌氧氨氧化菌(AnAOB)都是系统中的优势菌种,稳定运行阶段丰度分别达到16. 80%和23. 17%,而主要干扰菌群亚硝酸盐氧化菌(NOB)和反硝化菌(DNB)被成功抑制,反硝化菌丰度仅为3. 66%,几乎未检测出NOB。NAUTO~(TM)工艺启动时间短、运行负荷高、运行控制稳定,适合于自养脱氮的工程应用。     

磁性颗粒对厌氧氨氧化启动过程的影响

为探究磁性颗粒对厌氧氨氧化启动过程的影响,采用2个ASBR反应器进行实验,其中一个反应器不添加磁性颗粒,另一个反应器添加磁性颗粒,初步探明了磁场对ASBR反应器内氮转移过程的影响机理。通过小试方式对比研究了不同磁性颗粒投加量对于反应周期内氨氮和亚硝态氮去除效能以及脱氢酶活性的影响。结果表明,磁场的存在能够促进厌氧氨氧化启动过程中的优势菌落演替以及厌氧氨氧化菌的富集,有效缩短厌氧氨氧化的启动周期;投加30 g/L磁性颗粒可以有效提升微生物的活性,提高反应速率。     

聚氨酯生物膜反应器的厌氧氨氧化研究

以模拟高氨氮废水为进水,在聚氨酯填料生物膜反应器中实现厌氧氨氧化,考察了其脱氮性能。在运行稳定期,系统对氨氮、亚硝酸盐氮和总氮的去除率分别达到90.1%、89.3%和85.5%;总氮负荷最高达到17.6 kg/(m3·d)。进水亚硝酸盐氮浓度达到271.2~314.0 mg/L时会抑制厌氧氨氧化菌活性,影响厌氧氨氧化反应。进出水pH值的差值可以反映系统的脱氮效果,相对于进水pH值,出水pH值越高,说明系统的脱氮效果越好。应用电子显微镜和扫描电镜观察生物膜的形态,反应器底部生物膜颜色较浅,呈黄褐色,以丝状菌和长杆菌为主,而顶部生物膜颜色较深,呈棕红色,以短杆菌和球菌为主。     

Evaluation of autotrophic growth of ammonia-oxidizers associated with granular activated carbon used for drinking water purification by DNA-stable isotope probing

Nitrification is an important biological function of granular activated carbon (GAC) used in advanced drinking water purification processes. Newly discovered ammonia-oxidizing archaea (AOA) have challenged the traditional understanding of ammonia oxidation, which considered ammonia-oxidizing bacteria (AOB) as the sole ammonia-oxidizers. Previous studies demonstrated the predominance of AOA on GAC, but the contributions of AOA and AOB to ammonia oxidation remain unclear. In the present study, DNA-stable isotope probing (DNA-SIP) was used to investigate the autotrophic growth of AOA and AOB associated with GAC at two different ammonium concentrations (0.14 mg N/L and 1.4 mg N/L). GAC samples collected from three full-scale drinking water purification plants in Tokyo, Japan, had different abundance of AOA and AOB. These samples were fed continuously with ammonium and ¹³C-bicarbonate for 14 days. The DNA-SIP analysis demonstrated that only AOA assimilated ¹³C-bicarbonate at low ammonium concentration, whereas AOA and AOB exhibited autotrophic growth at high ammonium concentration. This indicates that a lower ammonium concentration is preferable for AOA growth. Since AOA could not grow without ammonium, their autotrophic growth was coupled with ammonia oxidation. Overall, our results point towards an important role of AOA in nitrification in GAC filters treating low concentration of ammonium.     

高浓度消毒剂对活性污泥系统中微生物的影响

针对污水厂活性污泥易于发生丝状菌污泥膨胀问题,以西安市第二污水处理厂活性污泥为研究对象,在次氯酸钠投加量为15 mg/L的条件下,探索高浓度消毒剂对活性污泥中微生物的杀灭效果以及对胞外聚合物(EPS)含量和不同类型微生物活性的影响。结果表明,高浓度次氯酸钠能有效杀灭丝状菌,从而控制污泥的丝状膨胀现象,但在杀灭丝状菌的同时也会影响菌胶团絮体内的部分微生物,且对不同微生物的杀灭效果不同,亚硝酸盐氧化菌(NOB)是最易被杀灭的类型。当次氯酸钠投加量为15 mg/L时,反应3 h后污泥胞外聚合物总含量降低了15. 48%,硝化活性丧失殆尽且再未恢复,反硝化活性下降明显;恢复7 d后,絮体内部微生物可以得到有效恢复,而丝状菌大多依然处于死亡状态,EPS总含量继续下降。总之,高浓度消毒剂作用于活性污泥后,可以达到控制丝状菌的目的,但是污泥的硝化和反硝化活性也受到了影响。     

Effect of temperature and disinfection strategies on ammonia-oxidizing bacteria in a bench-scale drinking water distribution system

The establishment of ammonia-oxidizing bacteria (AOB), a group of autotrophic microorganisms responsible for nitrification in chloraminated distribution systems, was studied in a bench-scale distribution system. The potential significance of temperature and disinfectant residual associated with chloramination in full-scale drinking water distribution systems was assessed. Biofilm development was primarily monitored using AOB abundance and nitrite concentrations. The bench-scale system was initially operated under typical North American summer (22 degrees C) and fall (12 degrees C) temperatures, representing optimal and less optimal growth ranges for these microorganisms. Additional experimentation investigated AOB establishment at a suboptimal winter distribution system temperature of 6 degrees C. The effect of chloramine residual on AOB establishment was studied at higher (0.2-0.6mg/L) and lower (0.05-0.1mg/L) ranges, using a 3:1 (w/w) chlorine:ammonia dosing ratio. Conditions were selected to represent those typically found in a North American distribution system, in areas of low flow and longer retention times, respectively. Finally, the effect of a free chlorine residual on an established nitrifying biofilm was briefly examined. Results clearly indicate that AOB development occurs at all examined temperatures, as well as at selected monochloramine residuals. The maintenance of a disinfectant residual was difficult at times, but was more inhibitory to the nitrifying biofilm than the lower temperature. It can be concluded from the data that nitrification may not be adequately inhibited during the winter months, which may result in more advanced stages of nitrification the following season. Free chlorination can be effective in controlling AOB activity in the short term, but may not prevent reestablishment of a nitrifying biofilm upon return to chloramination.     

Diversity of nitrifying bacteria in full-scale chloraminated distribution systems

Chloramination for secondary disinfection of drinking water often promotes the growth of nitrifying bacteria in the distribution system due to the ammonia introduced by chloramine formation and decay. This study involved the application of molecular biology techniques to explore the types of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) present in several full-scale chloraminated systems. The results of AOB community characterization indicated the ubiquitous detection of representatives from the Nitrosomonas genus, with Nitrosospira constituting a negligible or small fraction of the AOB community in all but one sample. Cloning and sequencing demonstrated the presence of AOB representatives within the Nitrosomonas oligotropha cluster, a phylogenetic subgroup of AOB from which isolates demonstrate a high affinity for ammonia. For the NOB communities, Nitrospira were detected in most of the samples, while Nitrobacter were only detected in a few samples. These results provide insight into the types of AOB responsible for nitrification episodes in full-scale chloraminated systems, which should help direct future studies aimed at characterizing relevant AOB growth and inactivation properties. Furthermore, the detection of NOB in most of the samples suggests a need to evaluate the contribution of biological nitrite oxidation relative to chemical oxidation in these systems.     

固定化氨氧化菌短程硝化的启动研究

采用亲水性玻璃态单体,应用辐射技术制备生物相容性高分子共聚物载体,使用固定化细胞增殖技术对氨氧化菌进行固定化,并以流化床为生物反应器,采用SBR运行方式对人工配水进行短程硝化的启动研究.结果表明:当进水氨氮浓度为100、75、50和25mg/L时,对氨氮的的去除率分别为98.6%、99.1%、98.8%和99.8% ,亚硝化率分别为 98.6%、94,5%、95.2%和94.7%:对氨氮的去除速率由开始时的10.6mg/(L·d)提高到25.7mg/(L·d),耗氧速率(OUR)则由0.37mg/(L·d)提高到1.12mg/(L·d).可见,该方法具有启动速度快、亚硝化程度高、容易控制等优点.     

沸石SBR/缺氧上升流污泥床实现氧化铁红废水脱氮

采用沸石序批式反应器(ZSBR)与缺氧上升流污泥床反应器(A-USB)组合工艺处理氧化铁红高氨氮废水,探究ZSBR稳定亚硝化特性以及组合工艺的脱氮性能。结果表明,通过游离氨(FA)抑制亚硝酸盐氧化菌(NOB),ZSBR可实现稳定高效的完全亚硝化。在进水NH4+-N浓度约为700 mg/L的情况下,ZSBR的出水NH4+-N基本稳定在30 mg/L以下,亚硝化率(NAR)维持在95%以上,平均亚硝酸盐产率(NPR)最高可达0. 68 kg/(m³·d)。提升外回流比能够有效利用A-USB反硝化产生的碱度并减少ZSBR中碳酸氢钠碱度的投加量。以葡萄糖作为外加碳源进行反硝化试验,ZSBR出水经过A-USB反硝化处理后,总氮去除率(NRE)能够较稳定维持在85%以上,最高总氮去除负荷(NRR)可达5. 10 kg/(m³·d)。高通量测序分析表明,ZSBR样品中AOB(Nitrosomonas)的相对丰度达到了50. 93%,未检测出NOB,而具有反硝化功能的副球菌属、丛毛单胞菌属和假单胞菌属的相对丰度总占比可达7. 05%,进一步验证了组合工艺高效且稳定的脱氮性能。     

Occurrence of nitrifiers and diversity of ammonia-oxidizing bacteria in developing drinking water biofilms

We studied the population dynamics of nitrifying bacteria during the development of biofilms up to 233 or 280 days on polyvinylchloride pipes connected to two full-scale drinking water distribution networks supplying processed and chloraminated surface water. The numbers of nitrifiers in biofilms were enumerated at intervals of 10–64 days by the most probable number (MPN) method at waterworks and at several study sites in distribution network areas. The numbers of nitrifiers increased towards the distal sites. The highest detected MPN counts of ammonia-oxidizing bacteria (AOB) for study areas 1 and 7 were 500 MPN cm⁻² and 1.0×10⁶ MPN cm⁻², and those of nitrite-oxidizing bacteria (NOB) 96 MPN cm⁻² and 2.2×10³ MPN cm⁻², respectively. The diversity of AOB was determined by PCR amplifying, cloning and sequencing the partial ammonia monooxygenase (amoA) gene of selected biofilm samples presenting different biofilm ages. The PCR primers used, A189 and A682, also amplified a fragment of particulate methane monooxygenase (pmoA) gene of methane-oxidizing bacteria. The majority of biofilm clones (24 out of 30 studied) contained Nitrosomonas amoA-like sequences. There were only two pmoA-like sequences of Type I methanotrophs, and four sequences positioned in amoA/pmoA sequence groups of uncultured bacteria. From both study area very similar or even completely identical Nitrosomonas amoA-like sequences were obtained despite of high difference in AOB numbers. The results show that the conditions in newly formed biofilms in drinking water distribution systems favor the growth of Nitrosomonas-type AOB.     

Dynamic and distribution of ammonia-oxidizing bacteria communities during sludge granulation in an anaerobic-aerobic sequencing batch reactor

The structure dynamic of ammonia-oxidizing bacteria (AOB) community and the distribution of AOB and nitrite-oxidizing bacteria (NOB) in granular sludge from an anaerobic-aerobic sequencing batch reactor (SBR) were investigated. A combination of process studies, molecular biotechniques and microscale techniques were employed to identify and characterize these organisms. The AOB community structure in granules was substantially different from that of the initial pattern of the inoculants sludge. Along with granules formation, the AOB diversity declined due to the selection pressure imposed by process conditions. Denaturing gradient gel electrophoresis (DGGE) and sequencing results demonstrated that most of Nitrosomonas in the inoculating sludge were remained because of their ability to rapidly adapt to the settling-washing out action. Furthermore, DGGE analysis revealed that larger granules benefit more AOB species surviving in the reactor. In the SBR were various size granules coexisted, granule diameter affected the distribution range of AOB and NOB. Small and medium granules (d < 0.6 mm) cannot restrict oxygen mass transfer in all spaces of the sludge. Larger granules (d > 0.9 mm) can result in smaller aerobic volume fraction and inhibition of NOB growth. All these observations provide support to future studies on the mechanisms responsible for the AOB in granules systems.     

Operation of suspended-growth shortcut biological nitrogen removal (SSBNR) based on the minimum/maximum substrate concentration

This study exploited the concept of the minimum/maximum substrate concentrations (MSC values) for identifying proper start-up conditions and achieving stable and low effluent total ammonium nitrogen (TAN) concentrations in suspended-growth short-cut biological nitrogen removal (SSBNR). Calculations based on the MSC concept indicated that S_Dmax, the TAN concentration above which ammonium-oxidizing bacteria (AOB) are washed out, was around 450 mgTAN/L at the given operating conditions of 2 mg/L of dissolved oxygen and pH 8, while nitrite-oxidizing bacteria (NOB) should be washed out at around 40 mgTAN/L. Therefore, the experimental research was focused on the optimal TAN-concentration range for SSBNR, between 50 and 100 mg/L. Experimental results showed that a nitrification reactor with initial TAN concentration above 450 mg/L did not give a successful start-up. However, two days of starvation, which decreased the TAN concentration in the reactor to 95 mg/L, stabilized the reaction quickly, and stable SSBNR was sustained thereafter with 80 mgTAN/L and 98% nitrite accumulation in the reactor. During stable SSBNR, the removal ratio of chemical oxygen demand per nitrite nitrogen (ΔCOD/ΔNO₂-N) for denitrification was 1.94 gCOD/gN, which is around 55% of that required for nitrate denitrification. Based on a clone library, Nitrosomonas occupied 14% of the total cells, while the sum of Nitrobacter and Nitrospira was less than the detection cut-off of 2%, confirming the NOB were washed out during SSBNR. A spiking test that doubled the influent ammonium loading caused the TAN concentration in the reactor to reach washout for AOB, which lasted until the loading was reduced. Thus, a loading increase should be controlled carefully such that the system does not exceed the washout range for AOB.     

缺氧生物膜滤池的自养脱氮性能研究

在成功实现亚硝酸盐自养脱氮(厌氧氨氧化)的基础上,探讨了亚硝酸盐浓度对缺氧生物膜滤池脱氮性能的影响。结果显示,在一定范围内提高亚硝酸盐浓度可加快氨氮去除速率,当NO2--N为118.4 mg/L时氨氮去除速率达到最大;此后,进一步提高进水NO2--N浓度会对氨氮的去除产生明显的抑制作用,导致反应速率下降,但此时的厌氧氨氧化菌仍具有较高的活性;为获得良好的脱氮效果,应控制进水NO2--N/NH4 -N值为1.3。