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1.
With the increase in industrial and agricultural activities, a large amount of nitrogenous compounds are released into the environment, leading to nitrate pollution. The perilous effects of nitrate present in the environment pose a major threat to human and animal health. Bioremediation provides a cost-effective and environmental friendly method to deal with this problem. The process of aerobic denitrification can reduce nitrate compounds to harmless dinitrogen gas. This review provides a brief view of the exhaustive role played by aerobic denitrifiers for tackling nitrate pollution under different ecological niches and their dependency on various environmental parameters. It also provides an understanding of the enzymes involved in aerobic denitrification. The role of aerobic denitrification to solve the issues faced by the conventional method (aerobic nitrification–anaerobic denitrification) in treating nitrogen-polluted wastewaters is elaborated. 相似文献
2.
极端条件下异养硝化-好氧反硝化菌脱氮的研究进展 总被引:5,自引:0,他引:5
异养硝化-好氧反硝化(HN-AD)是对传统自养硝化异养反硝化理论的丰富与突破。HN-AD菌在好氧条件下可快速实现氨氮、硝态氮(NO_3~–-N)、亚硝态氮(NO_2~–-N)三氮同步脱除。它们不仅具有分布范围广、适应能力强、代谢通路特殊等特点,而且还具有世代时间短、脱氮速率快、高活性持久等独特优势,在高盐、低温、高氨氮等极端条件表现出了巨大的脱氮潜力,因此在废水生物脱氮领域受到广泛关注。文中在介绍HN-AD菌属类别及代谢机理的基础上,重点总结了在高盐、低温、高氨氮等极端条件下进行氨氮脱除的HN-AD种属,系统分析了它们在极端条件下的脱氮特性及潜力,并简述了HN-AD菌在极端条件下的工艺应用研究进展,最后展望了HN-AD脱氮技术的应用前景和研究方向。 相似文献
3.
Thiosphaera pantotropha: a sulphur bacterium capable of simultaneous heterotrophic nitrification and aerobic denitrification 总被引:2,自引:0,他引:2
A.B. Gupta 《Enzyme and microbial technology》1997,21(8):589-595
Thiosphaera pantotropha, a facultative anaerobe is capable of mixotrophic and heterotrophic growth on a wide range of substrates. It can oxidize reduced sulfur compounds, nitrify ammonia heterotrophically to nitrite, and reduce nitrate or nitrite to nitrogen gas irrespective of the ambient dissolved oxygen concentration.1 The ammonia oxygenase has similarities with that of autotrophic nitrifiers (such as, light sensitivity, Mg2+ requirement, and NAD(P)H utilization), so has hydroxylamine oxidoreductase (cytochrome C oxidation, hydrazine inhibition) but there are some differences too (e.g., hydroxylamine inhibition of ammonia oxidation).2 It is the denitrifying enzyme system expression and operation under aerobic conditions, however, which is shrouded with controversy. The typical enzyme system of the bacterium throws open interesting possibilities of its applications for wastewater treatment. T. pantotropha has been tested in mixed bacterial cultures in suspended as well as fixed film systems to treat simulated industrial and domestic wastewaters. It has also been used in a flocculating algal-bacterial system to treat synthetic fertilizer wastewater. Fixed film systems have yielded better results. High rates of simultaneous removal of organics and nitrogen have been achieved. This indicates a vast improvement over conventional treatment strategies. 相似文献
4.
【背景】城市垃圾渗滤液是一种成分复杂的有机废水,含氮量高,如果未经处理直接排放到环境中会造成严重的环境污染。【目的】筛选可以耐受垃圾渗滤液中高浓度氨氮并高效去除污水中氮素的异养硝化好氧反硝化菌株,为解决垃圾渗滤液的氮素污染提供功能菌株。【方法】从垃圾渗滤液中筛选分离能耐受高氨氮浓度的菌株,通过测定各菌株的脱氮能力,筛选到一株脱氮能力最强的菌株,命名为U1,通过测定16S rRNA基因序列和生理生化特性确定该菌株为铜绿假单胞菌。进一步研究了菌株U1在不同初始氨氮浓度、碳源、转速、初始pH、碳氮比等单因素变量下的脱氮能力,并结合L9(34)正交试验研究了菌株U1的最佳脱氮条件。【结果】分离出一株铜绿假单胞菌并命名为U1。该菌株的最优脱氮条件为:初始氨氮浓度为1 000 mg/L,红糖和柠檬酸三钠的混合碳源,pH 6.0,C/N为10,转速为130 r/min,菌株U1的最大总氮去除率为64.37%,最大氨氮去除率为76.73%。对于总氮和氨氮含量分别是2 345 mg/L和1 473.8 mg/L的垃圾渗滤液,菌株U1最大总氮去除率为27.86%... 相似文献
5.
Biological nitrogen removal with nitrification and denitrification via nitrite pathway 总被引:23,自引:0,他引:23
Presently, the wastewater treatment practices can be significantly improved through the introduction of new microbial treatment technologies. To meet increasingly stringent discharge standards, new applications and control strategies for the sustainable removal of ammonium from wastewater have to be implemented. Partial nitrification to nitrite was reported to be technically feasible and economically favorable, especially when wastewater with high ammonium concentrations or low C/N ratios is treated. For successful implementation of the technology, the critical point is how to maintain partial nitrification of ammonium to nitrite. Partial nitrification can be obtained by selectively inhibiting nitrite oxidizing bacteria through appropriate regulation of the system’s DO concentration, microbial SRT, pH, temperature, substrate concentration and load, operational and aeration pattern, and inhibitor. The review addressed the microbiology, its consequences for their application, the current status regarding application, and the future developments. 相似文献
6.
一株异养硝化-反硝化不动杆菌的分离鉴定及脱氮活性 总被引:4,自引:0,他引:4
[目的]分离筛选并鉴定一株异养硝化-反硝化细菌,并探讨其在脱氮中的作用.[方法]富集培养分离筛选微生物,通过形态观察和生理生化特征及16S rDNA鉴定细菌,定时测定其OD600研究生长曲线,正交试验研究其脱氮影响因素和最佳条件,与污水处理厂活性污泥共同作用检验其脱氮活性.[结果]分离到一株异养硝化-反硝化细菌,鉴定结果表明是一株不动杆菌,命名为Acinetobacter sp.YF14,这是已知报道的第一株进行异养硝化和好氧反硝化的不动杆菌.该菌在12 h时进入对数期,22 h时进入稳定期,45 h以后进入衰亡期.该菌能进行异养硝化,3d后氨氮和总氮的去除率可以达到92%和91%,且无硝酸盐氮和亚硝酸盐氮积累.好氧条件下该菌能进行反硝化,在硝酸盐和亚硝盐培养基中均能将氮几乎完全去除.对该菌脱氮的影响程度大小依次为转速>接种量>碳源>碳氮比> pH.当转速为160 r/min,碳源取葡萄糖,接种量1%,碳氮比为8∶1,pH为6.5时,脱氮效果最好.该菌株可以提高活性污泥对于生活污水总氮脱除率约30%.[结论]菌YF14可以明显加强活性污泥脱氮效果,显示了良好的应用前景. 相似文献
7.
【背景】水体中含氮物质的大量累积会造成水体富营养化、水生生物死亡等问题,严重威胁水生态环境,制约我国环境保护的持续发展。【目的】为去除生活污水中的含氮污染物,从羊粪堆肥中筛选出了一株具有异养硝化-好氧反硝化功能的细菌——约氏不动杆菌Acinetobacter johnsonii sp.N26,研究其脱氮性能和代谢途径。【方法】测定菌株N26在氨氮和硝态氮中的生长和脱氮曲线,通过单因素试验对其脱氮性能进行优化,通过氮平衡分析和功能基因鉴定研究其脱氮代谢途径。【结果】生长和脱氮曲线表明,菌株N26对初始浓度均为50 mg/L的氨氮和硝态氮的去除速度快、效率高,其中9 h内对氨氮的去除效率为95.5%,最大去除速率为5.330 mg/(L·h);15 h内对硝态氮的去除效率为93.6%,最大去除速率为3.147 mg/(L·h),且最终仅有少量硝酸盐、亚硝酸盐积累。脱氮性能优化结果表明,该菌株的最适氮源为氯化铵,最适碳源为丁二酸钠,最适温度为30℃,最适接种量为15%,最适p H值为8.0-9.0,最适碳氮比为15,最适转速为120 r/min,最适氮负荷≤300 mg/L (氨氮)。氮平衡... 相似文献
8.
Yanchen Liu Hanchang Shi Lan Xia Huiming Shi Tonggang Shen Zhiqiang Wang Gan Wang Yingzhe Wang 《Bioresource technology》2010,101(3):901-906
The study on the operational conditions of simultaneous nitrification and denitrification (SND) in the channel of oxidation ditch (OD) without the need for a special anoxic tank was carried out based on lab-scale and pilot-scale experiments using real domestic wastewater. The influence of sludge loading and component proportion in influent, temperature, hydraulic retention time (HRT), dissolved oxygen (DO) and operational mode on SND was investigated. The result indicated that the optimal DO (ODO) of SND occurrence was confirmed majorly by the sludge loading of influent and temperature, the high TCOD/NH3–N and short HRT can enhance the occurrence of SND. A new operational mode was proposed that achieved a higher removal efficiency of 60–70% for total nitrogen by SND with HRT of 4–6 h, and the concentrations of NH3–N and TN in effluent are less than 5 and 15 mg/L, respectively. 相似文献
9.
一株海水异养硝化-好氧反硝化菌系统发育及脱氮特性 总被引:9,自引:0,他引:9
【目的】确定一株分离自海水的异养硝化-好氧反硝化菌的系统发育地位并探索其脱氮特性和机理,以期为解释异养硝化-好氧反硝化机理以及改进海水养殖及废水的生物脱氮工艺提供理论依据。【方法】通过形态观察、生理生化实验和16S rRNA基因序列分析,鉴定该菌株;通过测定菌株在不同无机氮源降解测试液中的生长和脱氮效率,分析其异养硝化和好氧反硝化性能。【结果】经鉴定该菌株属于盐单胞菌属(Halomonas);最适生长条件为盐度3%、pH 8.5、温度28℃、碳氮比10:1,在盐度为15%的培养液中仍能生长;可以同时去除氨氮、亚硝酸氮和硝酸氮,24 h时对NH4+-N、NO2--N、和NO3--N的去除率可分别达到98.29%、99.07%、96.48%,3种形态无机氮同时存在时,会优先利用NH4+-N,且总无机氮去除率较单一存在时更高,说明该菌株可实现同步硝化反硝化。【结论】该分离自海水的异养硝化-好氧反硝化菌属于盐单胞菌属(Halomonas),在高盐环境中仍能生长,同时具有高效的异养硝化和好氧反硝化能力,能够独立完成脱氮的全部过程。 相似文献
10.
两株异养硝化细菌的分离鉴定及其脱氮特性 总被引:3,自引:0,他引:3
【目的】利用异养硝化培养基,从华中农业大学实验猪场污水中筛选得到2株具有较高脱氮效率的细菌。【方法】通过形态学特征及16S rDNA序列的系统发育分析,对分离菌株进行了鉴定。且对菌株P2和P9降解氨氮的相关特性也作了研究。此外,将菌株单独或混合接种于猪场污水,检测其处理实际污水的脱氮效果。【结果】初步判断菌株P2为副球菌属(Paracoccus sp.),P9为申氏杆菌属(Shinella sp.)。2株细菌能在有机物存在下进行异养硝化作用,经24h培养,菌株P2和P9对氨氮的去除率可达80%左右,同时未发现亚硝酸盐、硝酸盐积累;但菌株P2,P9不能以NO 3-或NO 2-为唯一氮源发生好氧反硝化作用。菌株P2和P9异养硝化的最适碳源为丁二酸钠,最适C/N比为9,且脱氮过程中pH值从6.8到8.9一直呈上升趋势。菌株对小分子碳源具有较强的依赖性,在加入小分子碳源的情况下,其对污水具有较强的脱氮能力,且这两个菌株混合施用较单独作用氨氮去除效果更好。【结论】菌株P2和P9脱氮能力较强,其在污水处理行业具有重要的应用前景。 相似文献
11.
Seong-Jin Lim Ra Kyung Moon Woo Gi Lee Sunhoon Kwon Byung Geon Park Ho Nam Chang 《Biotechnology and Bioprocess Engineering》2000,5(6):441-448
Experimental work was carried out on nitrogen and phosphorus removal from real wastewater using a bench-scale SBR process.
The phosphorus removal was stable and the phosphorus concentration remaining in the reactor was maintained within 1.5 ppm,
regard-less of the addition of an external carbon source. In the case of nitrogen, an external carbon source was necessary
for denitrification. The effect on denitrification with the addition of various carbon sources, such as glucose, methanol,
acetate, and propionate, was also investigated. Acetate was found to be the most effective among those tested in this study.
When 100 ppm (theoretical oxygen demand) of sodium acetate was added, the average rate of denitrifiaction was 2.73 mg NO3−-N (g MLSS)−1 h−1, which wasca. 4 times higher than that with the addition of 200 ppm of methanol. The phosphorus and nitrogen concentrations were both
maintained within 1.5 ppm by the addition of an appropriate amount of a carbon source during a long-term operation of the
SBR. The mathematical modeling was performed using Monod kinetics, other microbial kinetics, mass balances, and stoichiometry.
The modeling was found to be useful for predicting the SBR operation and optimizing the HRT. 相似文献
12.
Loss of nitrogen in compacted grassland soil by simultaneous nitrification and denitrification 总被引:12,自引:0,他引:12
The soils of mid-Wales in grazed permanent pasture usually exhibit stagnogley features in the top 4–10 cm even though on sloping sites, they are freely drained. Nitrogen is often poorly recovered under these conditions. Our previous studies suggest that continuing loss of available N through concurrent nitrification and denitrification might provide an explanation for poor response to fertilizer N. The work described was designated to further test this proposition. When NH
4
+
–N was applied to the surface of intact cores, equilibrated at –5kPa matric potential, about 70% of NH
4
+
–N initially present was lost within 56 days of incubation. Study of different sections of the cores showed a rise in NO
3
-
level in the surface 0–2.5 cm soil layer but no significant changes below this depth. The imbalance between NO
3
-
accumulation and NH
4
+
disappearance during the study indicated a simultaneous nitrification and denitrification in the system. Furthermore, the denitrification potential of the soil was 3–4 times greater than nitrification potential so no major build-up of NO
3
-
would be expected when two processes occur simultaneously in micro-scale. When nitrification was inhibited by nitrapyrin, a substantial amount of NH
4
+
–N remained in the soil and persisted till the end of the incubation. The apparent recovery of applied N increased and of the total amount of N applied, 50% more was recovered relative to without nitrapyrin. It appears that addition of nitrapyrin inhibited nitrification, and consequently denitrification, by limiting the supply of NO
3
-
for denitrifying organisms. Emission of N2O from the NH
4
+
amended soil cores further confirmed that loss of applied N was the result of both nitrification and denitrification, which occurred simultaneously in adjacent sites at shallow depths. This N loss could account for the poor response to fertilizer N often observed in pastoral agriculture in western areas of the UK. 相似文献
13.
A bioreactor system with 30 packed gel envelopes was installed in a thermal power plant for the removal of nitrogen from ammonia-containing desulfurization wastewater. Each envelope consisted of double-sided plate gels containing Nitrosomonas europaea and Paracoccus denitrificans cells with an internal space in between for injecting an electron donor. The envelope can remove ammonia from wastewater in a single step. When the wastewater was continuously treated with the bioreactor system, it removed 95.0% of the total nitrogen in the inlet, and the total nitrogen concentration in the outlet was below 9.0 mg L−1. The maximum nitrogen removal rate was 6.0 g day−1 per square meter of the gel area. The maximum utilization efficiency of the injected ethanol for denitrification was 98.4%, and the total organic carbon concentration in the outflow was maintained at a low level. Since the bioreactor system could use the electron donor effectively, it was not necessary to use an additional aerobic tank to remove the electron donor and a settling tank to segregate the surplus sludge containing bacteria from wastewater. Our concept of using packed gel envelopes would be highly effective for constructing a simple and efficient nitrogen removal system capable of simultaneous nitrification and denitrification. 相似文献
14.
Nitrogen removal in a wastewater treatment plant through biofilters: nitrous oxide emissions during nitrification and denitrification 总被引:1,自引:0,他引:1
In order to estimate N2O emissions from immersed biofilters during nitrogen removal in tertiary treatments at urban wastewater treatment plants (WWTPs), a fixed culture from the WWTP of “Seine Centre” (Paris conurbation) was subjected to lab-scale batch experiments under various conditions of oxygenation and a gradient of methanol addition. The results show that during nitrification, N2O emissions are positively related to oxygenation (R
2 = 0.99). However, compared to the rates of ammonium oxidation, the percentage of emitted N2O is greater when oxygenation is low (0.5–1 mgO2 L−1), representing up to 1% of the oxidized ammonium (0.4% on average). During denitrification, the N2O emission reaches a significant peak when the quantity of methanol allows denitrification of between 66% and 88%. When methanol concentrations lead to a denitrification of close to 100%, the flows of N2O are much lower and represent on average 0.2% of the reduced nitrate. By considering these results, we can estimate, the emissions of N2O during nitrogen removal, at the “Seine Centre” WWTP, to approximately 38 kgN-N2O day−1. 相似文献
15.
污水脱氮功能微生物的组学研究进展 总被引:2,自引:1,他引:2
生物脱氮是污水处理厂的核心,掌握生物脱氮过程相关微生物代谢特性,对于探索微生物资源和提高污水处理厂脱氮性能具有重要意义。近年来,分子生物学方法不断发展和改进,已被广泛应用于揭示脱氮微生物群落多样性、组成结构和潜在功能等方面,大幅提升了研究者们对污水生物脱氮系统中微生物,尤其是不可培养微生物的代谢机理、抑制调控原理及新型生物脱氮工艺途径的认识。本文对流行的分子生物学方法(16S rRNA基因测序、实时荧光定量PCR技术、宏基因组学、宏转录组学、宏蛋白质组学和代谢组学)进行了介绍,综述了其在硝化细菌、反硝化细菌、完全氨氧化细菌、厌氧氨氧化细菌、厌氧铁氨氧化细菌、硫酸盐型厌氧氨氧化细菌及亚硝酸盐/硝酸盐型厌氧甲烷氧化微生物等方面的研究进展,阐明了这些氮素转化微生物在氮循环过程的代谢途径和酶促反应,并从标准测定方法构建、不同方法的联用及跨学科结合和检测方法的简易化这3个方面展望了分子生物学方法的技术突破及其在污水生物处理系统中的应用前景。本综述从系统角度全面认识脱氮微生物群落及其结构,为未来污水处理生物脱氮微生物的研究提供了新方向。 相似文献
16.
海岸带地区的固氮、氨化、硝化与反硝化特征 总被引:9,自引:2,他引:9
海岸带是海洋环境中受人类活动影响最大、生物地球化学循环最为活跃的地区。这一地区氮的生物地球化学循环包括 :生物固氮、有机氮的氨化、氮的硝化、反硝化等 4个主要过程。概括性地介绍了有关这四个过程的发生机制、环境影响因素及研究方法等方面的研究动态、进展、存在的科学问题与今后的研究方向。过去十几年来 ,固氮主要集中在对束毛藻属的研究上 ,其间有两个重要发现 ,一是生物固氮在海洋氮循环中的作用远比人们以前的想象要重要得多 ;二是蓝细菌已经在海洋中存在了 2 0亿年 ,它们有可能调节大气中的 CO2 ,进而影响全球气候。由于有机物的结构千差万别 ,含氮有机物的氨化过程可能是一个简单的矿化反应 ,也有可能是一系列复杂的代谢过程 ,在水解酶的作用下含氮有机物降解为下一级化合物。硝化过程分两步进行 ,氨的硝化为反硝化细菌提供了重要的硝酸盐来源 ,通常采用同位素方法来研究硝化过程。发生在沉积物中的反硝化过程是氮循环的关键步骤 ,反硝化过程一方面减少了海水中初级生产者可利用的氮 ,另一方面产生了终结产物 N2 和 N2 O,而 N2 O是一种温室气体 ,可能影响全球气候变化 相似文献
17.
污水地下渗滤系统脱氮效果及动力学过程 总被引:2,自引:0,他引:2
建立了模拟污水地下渗滤过程的中试系统,重点考察了水力负荷对系统脱氮效率的影响情况,建立了描述地下渗滤系统微生物脱氮过程的动力学模型.结果表明:地下渗滤系统脱氮效果好,抗水力负荷冲击能力强,处理最佳水力负荷0.125m3· m-2· d-1,出水中氮浓度低于《城市污水再生利用——景观环境用水水质》标准( GB/T 18921-2002).地下渗滤系统硝化过程符合一级动力学模型NE=Noe-0.4812t,温度是影响硝化速率的主要因素,两者的关系是KT=0.2218×1.035(T-20);出水硝态氮浓度与水力停留时间之间呈负指数关系,可描述为C=16.3475e-0.2548t,碳源是引起反硝化速率变化的主要因子.在基质层垂直深度65 cm处二次补加生活污水,反硝化速率常数由0.0355提高到0.0488.强调地下渗滤系统的污水净化功能而忽视其生态服务功能,是系统运行中普遍存在的认识误区,过高的水力负荷不利于硝化-反硝化反应的顺利进行.地下渗滤系统运行应采取适宜的水力负荷方式,促进硝化-反硝化作用. 相似文献
18.
Pollution from concentrated animal feeding operations (CAFOs) are the most serious pollution source in China now, and swine wastewater contains high concentrations of nutrients such as chemical oxygen demand (COD), biochemical oxygen demand 5 (BOD5), ammonium, and emergent contaminants related to public health. Biological processes are the most popular treatment methods for COD and ammonium removal. Considering the low operation cost, easy maintenance and high removal rate of contaminants in recent years, nitrogen removal via nitrite and real-time control processes using oxidation-reduction potential (ORP) and/or pH as parameters to control the aerobic and anaerobic cycles of a system has received much attention for animal wastewater treatment. During the biological treatment process, the emergent contaminants such as estrogen, antibiotics, and disinfec-tion reagents have been the focus of research recently, and degradation bacteria and resistance bacteria have also been extracted from activated sludge. The microbial analysis technique is also advancement in the field of biodegrada-tion bacteria and resistance bacteria. All of these advance-ments in research serve to improve wastewater treatment and decrease environmental hazards, especially for using manure as a fertilizer source for crop production. 相似文献
19.
The development of simultaneous partial nitrification, ANAMMOX and denitrification (SNAD) process in a single reactor for nitrogen removal 总被引:2,自引:0,他引:2
The simultaneous partial nitrification, ANAMMOX and denitrification (SNAD) process was validated to potentially remove ammonium and COD from wastewater in a single, oxygen-limited, non-woven rotating biological contactor (NRBC) reactor. An ammonium conversion efficiency of 79%, TN removal efficiency of 70% and COD removal efficiency of 94% were obtained with the nitrogen and COD loading rate of 0.69 kgN/m(3)d and 0.34 kg/m(3)d, respectively. Scanning electron microscopy (SEM) observation and fluorescence in situ hybridizations (FISH) analysis revealed the existence of the dominant groups of bacteria. As a result, the aerobic ammonia-oxidizing bacteria (AOB), with a spot of aerobic heterotrophic bacteria were mainly distributed in the aerobic outer part of the biofilm. However, ANAMMOX bacteria with denitrifying bacteria were present and active in the anaerobic inner part of the SNAD biofilm. These bacteria were found to exist in a dynamic equilibrium to achieve simultaneous nitrogen and COD removal in NRBC system. 相似文献
20.
Challenges for simultaneous nitrification, denitrification, and phosphorus removal in microbial aggregates: mass transfer limitation and nitrous oxide production 总被引:10,自引:0,他引:10
The microbial community composition and activity was investigated in aggregates from a lab-scale bioreactor, in which nitrification, denitrification and phosphorus removal occurred simultaneously. The biomass was highly enriched for polyphosphate accumulating organisms facilitating complete removal of phosphorus from the bulk liquid; however, some inorganic nitrogen still remained at the end of the reactor cycle. This was ascribed to incomplete coupling of nitrification and denitrification causing NO(3)(-) accumulation. After 2 h of aeration, denitrification was dependent on the activity of nitrifying bacteria facilitating the formation of anoxic zones in the aggregates; hence, denitrification could not occur without simultaneous nitrification towards the end of the reactor cycle. Nitrous oxide was identified as a product of denitrification, when based on stored PHA as carbon source. This observation is of critical importance to the outlook of applying PHA-driven denitrification in activated sludge processes. 相似文献