低温贫营养好氧反硝化细菌SY13的反硝化特性

从底泥中分离出1株低温贫营养好氧反硝化细菌SY13,经常规生理生化鉴定和16SrDNA测序,鉴定出细菌SY13属于Acinetobactersp．。考察了温度、pH、C／N比及接种量对菌株SY13硝酸盐还原活性的影响,初始硝酸盐浓度为15mg／L左右,温度为15℃时低温贫营养好氧反硝化细菌SY13的硝酸盐去除率为49．26％,在中性环境适应性较强,pH值为7．0时72h的硝氮去除率达到58．08％,随着C／N比不断增加,菌株SY13硝酸盐的去除效果逐渐增强,接种量为10％时,菌株SY13培养72h后的硝氮去除率可达到59．62％。     

一株贫营养异养硝化-好氧反硝化菌的筛选及脱氮特性

为了探究并优化菌剂应用于微污染水源水体修复的机制和条件,主要针对水库沉积物内筛选出的贫营养好氧反硝化菌进行了菌种鉴定及脱氮特性研究,考察菌株在不同环境条件下的脱氮效果,明确了该菌株的最适宜生长条件,并基于水库水体中贫营养条件对菌株进行水源水库原水的驯化培养试验研究,以期实现该菌株对微污染水源水库原水中氮源污染物的脱除,为原位投菌技术实际工程应用提供理论依据。从微污染水源水库沉积物中驯化筛分出一株高效异养硝化-好氧反硝化菌A14,通过扫描电镜观察、生理生化特征、16S rRNA基因测序和Biolog GenⅢ鉴定,确定该菌株为革兰氏阴性短杆菌,鉴定为皮特不动杆菌（Acinetobacter pittii）。在好氧条件下,菌株细胞内表达反硝化功能基因napA,以NO3-为唯一氮源进行反硝化作用时,36 h时NO3-去除率为78.89%。以NH4+为唯一氮源时,48 h NH4+去除率为95.25%,TN去除率达80.42%,TOC去除率达98.30%,表明该菌株具有异养硝化-好氧反硝化特性。在改变环境条件过程中,该菌株在以乙酸钠为碳源,温度为30℃,C/N为12,pH为7,接种量为10%时,NO3-去除率最高为86.62%,并且在10℃下脱氮率达到40.18%。在水源水库原水脱氮实验中,接种处理TN去除率为50.95%,NO3-去除率为80.25%。结果表明,菌株A14在微污染水源水体菌剂脱氮修复中具有良好的应用潜力。     

一株轻度嗜盐反硝化菌的分离鉴定及特性

从处理高盐度废水的成熟活性污泥中分离筛选得到1株轻度嗜盐反硝化细菌YL-1.通过对该菌株的形态观察、生理生化实验以及16SrDNA基因序列分析,确定该菌株为迪茨氏菌(Dietziasp.).盐度影响实验表明,该菌株能在盐度为0～10%的培养液中生长,盐度为3%时D600nm达到最大,为2.002;当初始硝态氮浓度为120mg/L左右时,DO值对该菌株的反硝化效果几乎没有影响,NOX——N去除率均在90%以上,表明该菌为好氧反硝化菌;适于在碱性环境中生长,最适pH为7.5～8.5;能利用乙酸钠、蔗糖、葡萄糖、柠檬酸钠、丁二酸钠为碳源进行反硝化,以蔗糖为碳源时反硝化效果最好,NOX——N去除率达到99.8%;在25～30℃的温度范围内反硝化效果较好,30℃时菌株的NOX——N去除率超过90%.该菌在一定盐度下具有较好的反硝化作用,能为高盐度废水的生物处理提供一定的参考价值.     

一株好氧反硝化菌的分离鉴定及其混合应用特性研究

采用溴百里酚(BTB)鉴定培养基和稀释平板法从南京市某市政污水处理厂曝气池污水样本中分离筛选得到1株好氧反硝化细菌,经16S rDNA序列同源性比较和系统发育分析初步鉴定为反硝化产碱杆菌(Alcaligenes denitrificans),并将其命名为菌株BMB-N6.研究了菌株BMB-N6在不同浓度亚硝态氮条件下的反硝化能力,运用正交试验设计探讨了该菌株最适的好氧反硝化条件,并且在实验室和大田条件下分别考察了菌株BMB-N6与蛋白质降解菌BMB-LA和氨氮脱除菌BMB-HKF复配形成的混合菌制剂的反硝化能力.结果表明,菌株BMB-N6在8 h内对亚硝态氮的去除率可达94%,其最适亚硝态氮去除条件为摇床转速50 r·min-1,C/N比值4,pH 6,温度35 ℃.在实验室条件下以菌株BMB-N6为基础制成的混合菌制剂在12 h内可去除90%的亚硝态氮,在大田应用中7 d内可去除80%的亚硝态氮.     

一株好氧反硝化茵的分离鉴定及其混合应用特性研究

采用溴百里酚（BTB）鉴定培养基和稀释平板法从南京市某市政污水处理厂曝气池污水样本中分离筛选得到1株好氧反硝化细菌,经16SrDNA序列同源性比较和系统发育分析初步鉴定为反硝化产碱杆菌（Alcaligenes denitrificns）,并将其命名为菌株BMB—N6。研究了菌株BMB—N6在不同浓度亚硝态氮条件下的反硝化能力,运用正交试验设计探讨了该菌株最适的好氧反硝化条件,并且在实验室和大田条件下分别考察了菌株BMB—N6与蛋白质降解菌BMB-LA和氨氮脱除菌BMB—HKF复配形成的混合菌制剂的反硝化能力。结果表明,菌株BMB—N6在8h内对亚硝态氮的去除率可达94％,其最适亚硝态氮去除条件为摇床转速50r·min^-1,C／N比值4,pH6,温度35℃。在实验室条件下以菌株BMB-N6为基础制成的混合菌制剂在12h内可去除90％的亚硝态氮,在大田应用中7d内可去除80％的亚硝态氮。     

固定化反硝化菌在低污染水处理中脱氮性能研究

在面源低污染水的原位修复领域,人工湿地生物脱氮过程受温度、p H波动影响以及NO2--N积累抑制反硝化脱氮效果等问题,因此强化系统脱氮性能在实际工程应用中具有重要意义。固定化微生物技术具有环境变化适应能力以及耐毒害能力强等优点。该研究通过分离筛选高效反硝化菌,对其进行DNA序列分析鉴定及其种属和系统发育地位分析,并以包埋法加以固定,考察固定化反硝化菌在不同温度、p H、DO和C/N下的反硝化性能,分析各因素变化对固定化反硝化菌脱氮效果的影响,探究各影响因素对固定化反硝化菌脱氮性能的作用机理,以期为固定化反硝化菌强化人工湿地脱氮性能提供参考。经反硝化能力测定,筛选得到的高效反硝化菌株对NO3--N、TN的去除率分别为98.83%、98.36%,NO2--N积累量仅为0.28mg·L~(-1),24 h内脱氮效率为8.59 mg·L~(-1)·h~(-1),经16S r RNA测序结果表明该菌株与Pseudomonas stutzeri A1501的最大相似度为99.7%。采用PVA、SA为材料包埋固定该菌株,固定化反硝化菌的生物量为15.67 g·L~(-1),颗粒密度为0.93 g·m L~(-1)。通过对固定化反硝化菌处理低污染水的性能研究得知,p H、T、DO的波动对固定化反硝化菌的脱氮效果影响均小于游离反硝化菌,固定化反硝化菌在p H为7,θ为30℃,DO为0.87~1.54 mg·L~(-1),C/N为5时的脱氮效果最好。     

一株异养硝化细菌的脱氮特性及其初步应用

氮素超标是导致水体富营养化的重要原因之一,生物除氮是去除水体中氮元素的有效途径。从垃圾填埋场土壤中分离得到菌株WS-2,经16S rDNA鉴定为土壤杆菌(Agrobacterium sp.)。该菌可在42 h内去除95.8%的铵态氮,氮气、硝态氮和细胞内氮为主要产物,分别占初始氮量的42.4%、23.8%和19.4%。同时,该菌可在84 h内去除80.5%的硝态氮和97.1%的亚硝态氮,其中生成的氮气和细胞内氮分别占初始氮量的50.2%~51.0%和17.0%~17.8%。由此可见,菌株WS-2的优势在于不仅可以同步进行硝化和反硝化过程,而且还具有较高的氮气生成率和较低的细胞内氮积累量。进一步将该菌用于处理富营养化水体,发现将菌体固定于聚氨酯载体材料并辅以曝气措施,其对CODCr、总氮、铵态氮和总磷的去除率分别可达84.3%、71.3%、94.7%和55.6%,表明该菌具有修复富营养化水体的潜力。     

磁性壳聚糖凝胶微球固定反硝化菌去除地下水中硝酸盐氮

本研究从活性污泥中分离出氢自养反硝化细菌,在厌氧条件下利用氢气作为电子受体,将硝酸盐氮污染物彻底还原为氮气.通过原位共沉淀/柠檬酸钠交联法制备了一种磁性壳聚糖微球,将氢自养反硝化菌固定于磁性壳聚糖微球上组成固定化微生物反硝化体系.利用16SrDNA菌种鉴定、扫描电镜(SEM)、傅里叶红外光谱(FTIR)对固定化前后的材料进行了表征,并与游离的氢自养反硝化菌进行对比,同时进行静态批实验考察了在不同影响因素下硝酸盐去除效果.结果表明,分离出的氢自养反硝化菌属于陶厄氏菌属(MK928401),且被成功固定在磁性壳聚糖微球上;相同时间内,固定化氢自养反硝化菌对硝酸盐氮去除率高出游离细菌59%,说明固定化菌克服了由于游离菌易团聚而限制反硝化速率的缺点;磁性壳聚糖微球的加入,在一定程度上拓宽了氢自养反硝化菌对硝酸盐氮浓度的适应范围,同时拓宽了氢自养反硝化菌对pH的耐受范围;固定化氢自养反硝化菌经5次重复利用后,仍能高效还原硝酸盐氮,相比于游离细菌具有可回收和循环利用性.以上结果得出,以磁性壳聚糖微球固定氢自养反硝化菌,为高效去除地下水中的硝酸盐氮提供了一种更有效的途径.     

水库贫营养异养硝化-好氧反硝化菌Sxf14的脱氮特性

为利用生物强化法降低微污染源水中的氮素,从水库沉积物中筛选到一株好氧反硝化细菌Sx f14.通过扫描电镜和16S r RNA序列分析,鉴定其为不动杆菌属(Acinetobacter sp.),命名为Acinetobacter sp.Sxf14.同时,对该菌株脱氮特性进行研究,并将其接种到C/N(总有机碳与总氮的比值)为1.2的微污染水库源水中,以探究其对实际源水总氮的去除效果.结果显示:Sxf14能以硝酸盐和亚硝酸盐为唯一氮源进行好氧反硝化.反应48 h后,NO3--N和NO2--N的去除率分别达74.84(±0.86)%和40.52(±1.49)%,TN去除率最高达到65.07(±1.56)%和41.33(±0.98)%;在以NH4Cl为氮源的异养硝化系统内,该菌在48 h内使NH4+-N浓度由3.73(±0.08)mg/L降到1.28(±0.20)mg/L,氨氮去除率达到65.63(±1.39)%.72 h内,微污染水库源水的TN浓度由2.46(±0.02)mg/L降到1.68(±0.01)mg/L,去除率达到31.7(±0.14)%.因此,菌株Acinetobacter sp.Sxf14具有反硝化能力,能承受较低的碳氮比,降低微污染源水中的氮素,本研究可为微污染水体的菌剂修复技术提供科学依据.     

好氧同时硝化-反硝化菌的分离鉴定及系统发育分析

从土壤中分离到一株好氧同时硝化-反硝化菌,编号为SDN,该菌株革兰氏染色呈阳性,球状或杆状,菌落颜色橙红色.该菌株以硝酸钠为氮源时能进行好氧反硝化作用;以乙酸钠和硫酸铵分别为碳源和氮源能进行异养硝化作用,能以乙酰胺为唯一碳源和氮源进行生长.部分长度的16S rDNA序列分析表明,分离菌株SDN与Rhodococcusruber的16SrDNA序列具有99%相似性.并用PHYLIPS程序将该菌株与报道的相关微生物进行了系统发育分析.图4表1参13     

碳源及碳氮比对异养反硝化微生物异养反硝化作用的影响

碳源(甘油和柠檬酸钠)及碳氮比对纯培养的异养反硝化菌HP1 (Pseudomonasalcaligenes)异养反硝化能力影响的试验表明,碳源种类对硝酸还原酶活性没有明显影响,对氧化亚氮还原酶活性有影响。批式培养方式下最适C/N为8,菌株HP1可以利用NO-3 作为唯一氮源进行反硝化作用,证明HP1至少有2种硝酸还原途径。连续培养方式下温度对菌株HP1异养反硝化作用中间产物的积累有影响,不同C/N时均有NH+4 积累,C/N为3时还有NO-2 的积累。     

应用在线传感器实现前置反硝化工艺生物脱氮的过程控制

为了实现前置反硝化工艺硝化反硝化反应的过程控制,系统地研究了硝化反硝化过程中DO、pH和ORP的变化规律,并考察了它们作为硝化反硝化过程控制参数的可行性.结果表明,pH值在缺氧区的变化分为下降型和上升型,从而指示系统反硝化反应进行的程度以及内循环回流量是否充足;缺氧区末端ORP值和硝酸氮浓度具有较好的相关性;好氧区第1格室的DO浓度可以指示进水氨氮负荷高低;pH值在好氧区的变化也可分为下降型和上升型,可指示系统硝化反应进行的程度、曝气量和碱度是否充足;好氧区末端ORP值与出水氨氮、硝酸氮浓度具有很好的相关性.在此基础上建立了硝化反硝化反应在线控制系统,从而实现曝气量、内循环回流量和外碳源投加量的在线控制,提高系统出水水质、降低运行费用.图7表1参8     

复合自养反硝化材料处理低碳氮比硝酸盐污水

作为一种典型的硝酸盐污水,低碳氮比硝酸盐污水的存在具有广泛性,且对生态环境和居民健康带来的危害日益突出。本研究构建了复合硫自养反硝化(CSAD)体系,基于硫-碳酸钙型复合材料与微生物,进行低碳氮比硝酸盐污水的深度处理,分析了材料投加量、粒径以及进水硝酸盐浓度对CSAD的影响,并探究了硝酸盐去除的动力学行为。结果表明,体系中NO₃^--N去除率为52.7%—99.9%,NO₂^--N在NO₃^--N浓度降低至5 mg·L^-1左右时由积累转变为迅速下降;复合材料投加量较低(1 g·L^-1)时,自养阶段体系内电子供体数量不能满足微生物反硝化需求;增大投加量可提高NO₃^--N去除速率并降低反应过程中NO₂^--N积累量。当粒径大于2.5 mm时,复合材料利用效率显著降低。Michaelis-Menten方程拟合表明,投加量增大提高了酶与底物亲和力,促进V_max增大,粒径减小增大了亲和力,但V_max却减小。进水NO₃^--N浓度增大至50 mg·L^-1时,亲和力显著降低,但V_max增大可能与微生物数量增多有关。本研究从动力学角度上揭示了不同工艺参数对复合材料反硝化过程的影响,同时也为基于复合自养反硝化材料的低碳氮比污水深度处理的实际工程应用提供参考。     

Factors affecting simultaneous nitrification and denitrification in an SBBR treating domestic wastewater

An aerobic sequencing batch biofilm reactor (SBBR) packed with Bauer rings was used to treat real domestic wastewater for simultaneous nitrification and denitrification. The SBBR is advantageous for creating an anoxic condition, and the biofilm can absorb and store carbon for good nitrification and denitrification. An average concentration of oxygen ranging from 0.8 to 4.0 mg/L was proved very efficient for nitrification and denitrification. Volumetric loads of TN dropped dramatically and effluent TN concentration increased quickly when the concentration of average dissolved oxygen was more than 4.0 mg/L. The efficiency of simultaneous nitrification and denitrification (SND) increased with increasing thickness of the biofilm. The influent concentration hardly affected the TN removal efficiency, but the effluent TN increased with increasing influent concentration. It is suggested that a subsequence for denitrification be added or influent amount be decreased to meet effluent quality requirements. At optimum operating parameters, the TN removal efficiency of 74%–82% could be achieved.     

N fertilization effects on denitrification and N cycling in an aggrading forest.

We investigated N cycling and denitrification rates following five years of N and dolomite amendments to whole-tree harvested forest plots at the long-term soil productivity experiment in the Fernow Experimental Forest in West Virginia, USA. We hypothesized that changes in soil chemistry and nutrient cycling induced by N fertilization would increase denitrification rates and the N2O:N2 ratio. Soils from the fertilized plots had a lower pH (2.96) than control plots (3.22) and plots that received fertilizer and dolomite (3.41). There were no significant differences in soil %C or %N between treatments. Chloroform-labile microbial biomass carbon was lower in fertilized plots compared to control plots, though this trend was not significant. Extractable soil NO3- was elevated in fertilized plots on each sample date. Soil-extractable NH4+, NO3-, pH, microbial biomass carbon, and %C varied significantly by sample date suggesting important seasonal patterns in soil chemistry and N cycling. In particular, the steep decline in extractable NH4+ during the growing season is consistent with the high N demands of a regenerating forest. Net N mineralization and nitrification also varied by date but were not affected by the fertilization and dolomite treatments. In a laboratory experiment, denitrification was stimulated by NO3- additions in soils collected from all field plots, but this effect was stronger in soils from the unfertilized control plots, suggesting that chronic N fertilization has partially alleviated a NO3- limitation on denitrification rates. Dextrose stimulated denitrification only in the whole-tree-harvest soils. Denitrification enzyme activity varied by sample date and was elevated in fertilized plots for soil collected in July 2000 and June 2001. There were no detectable treatment effects on N2O or N2 flux from soils under anaerobic conditions, though there was strong temporal variation. These results suggest that whole-tree harvesting has altered the N status of these soils so they are less prone to N saturation than more mature forests. It is likely that N losses associated with the initial harvest and high N demand by aggrading vegetation is minimizing, at least temporarily, the amount of inorganic N available for nitrification and denitrification, even in the fertilized plots in this experiment.     

Effects of restoration and reflooding on soil denitrification in a leveed Midwestern floodplain.

River floodplains have the potential to remove nitrate from water through denitrification, the anaerobic microbial conversion of nitrate to nitrogen gas. An important factor in this process is the interaction of river water with floodplain soil; however, many rivers have been disconnected from their historic floodplains by levees. To test the effect of reflooding a degraded floodplain on nitrate removal, we studied changes in soil denitrification rates on the Baraboo River floodplain in Wisconsin, USA, as it underwent restoration. Prior to this study, the site had been leveed, drained, and farmed for more than 50 years. In late fall 2002, the field drainage system was removed, and a gate structure was installed to allow controlled flooding of this site with river water. Soil moisture was extremely variable among zones and months and reflected local weather. Soil organic matter was stable over the study period with differences occurring along the elevation gradient. High soil nitrate concentrations occurred in dry, relatively organic-poor soil samples and, conversely, all samples with high moisture soils characterized by low nitrate. We measured denitrification in static cores and potential denitrification in bulk samples amended with carbon and nitrogen, one year before and two years following the manipulation. Denitrification rates showed high temporal and spatial variability. Static core rates of individual sites ranged widely (from 0.00 to 16.7 microg N2O-N x [kg soil](-1) x h(-1), mean +/- SD = 1.10 +/- 3.02), and denitrification enzyme activity (DEA) rates were similar with a slightly higher mean (from 0.00 to 15.0 microg N2O-N x [kg soil](-1) x h(-1), 1.41 +/- 1.98). Denitrification was not well-correlated with soil nitrate, organic matter content, or moisture levels, the three parameters typically thought to control denitrification. Static core denitrification rates were not significantly different across years, and DEA rates decreased slightly the second year after restoration. These results demonstrate that restored agricultural soil has the potential for denitrification, but that floodplain restoration did not immediately improve this potential. Future floodplain restorations should be designed to test alternative methods of increasing denitrification.     

Effects of stream restoration on denitrification in an urbanizing watershed.

Increased delivery of nitrogen due to urbanization and stream ecosystem degradation is contributing to eutrophication in coastal regions of the eastern United States. We tested whether geomorphic restoration involving hydrologic "reconnection" of a stream to its floodplain could increase rates of denitrification at the riparian-zone-stream interface of an urban stream in Baltimore, Maryland. Rates of denitrification measured using in situ 15N tracer additions were spatially variable across sites and years and ranged from undetectable to >200 microg N x (kg sediment)(-1) x d(-1). Mean rates of denitrification were significantly greater in the restored reach of the stream at 77.4 +/- 12.6 microg N x kg(-1) x d(-1) (mean +/- SE) as compared to the unrestored reach at 34.8 +/- 8.0 microg N x kg(-1) x d(-1). Concentrations of nitrate-N in groundwater and stream water in the restored reach were also significantly lower than in the unrestored reach, but this may have also been associated with differences in sources and hydrologic flow paths. Riparian areas with low, hydrologically "connected" streambanks designed to promote flooding and dissipation of erosive force for storm water management had substantially higher rates of denitrification than restored high "nonconnected" banks and both unrestored low and high banks. Coupled measurements of hyporheic groundwater flow and in situ denitrification rates indicated that up to 1.16 mg NO3(-)-N could be removed per liter of groundwater flow through one cubic meter of sediment at the riparian-zone-stream interface over a mean residence time of 4.97 d in the unrestored reach, and estimates of mass removal of nitrate-N in the restored reach were also considerable. Mass removal of nitrate-N appeared to be strongly influenced by hydrologic residence time in unrestored and restored reaches. Our results suggest that stream restoration designed to "reconnect" stream channels with floodplains can increase denitrification rates, that there can be substantial variability in the efficacy of stream restoration designs, and that more work is necessary to elucidate which designs can be effective in conjunction with watershed strategies to reduce nitrate-N sources to streams.     

Advanced nitrogen removal by pulsed sequencing batch reactors (SBR) with real-time control

The feasibility of pH and oxidation reduction potential (ORP) as on-line control parameters to advance nitrogen removal in pulsed sequencing batch reactors (SBR) was evaluated. The pulsed SBR, a novel operational mode of SBR, was utilized to treat real municipal wastewater accompanied with adding ethanol as external carbon source. It was observed that the bending-point (apex and knee) of pH and ORP profiles can be used to control denitrification process at a low influent C/N ratio while dpH/dt can be used to control the nitrification and denitrification process at a high influent C/N ratio. The experimental results demonstrated that the effluent total nitrogen can be reduced to lower than 2 mg/L, and the average total nitrogen (TN) removal efficiency was higher than 98% by using real-time controll strategy.