Influence of dissolved oxygen concentration and aeration time on nitrite accumulation in partial nitrification process

This study investigated the influence of dissolved oxygen concentration and aeration time on nitrification and nitrite accumulation in an attempt to optimize the recently developed biological-partial-nitritation process for the treatment of strong nitrogen wastewaters. Investigation of dissolved oxygen concentration on ammonium and nitrite oxidation was carried out in a batch reactor. The dissolved oxygen concentration of 0.5 mg O₂/L inhibited both ammonium as well as nitrite oxidation, while increase of dissolved oxygen concentration to ～1 mg O₂/L increased the ammonium oxidation rate and was comparable to that at higher dissolved oxygen concentrations. Experiments were carried out in a sequencing batch reactor for more than 100 days to investigate the influence of aeration time on nitrite accumulation. The dissolved oxygen concentration was controlled at ～1.0 mg O₂/L (in the range of 0.8–1.5 mg/L) during the aeration stage, and volatile suspended solid was maintained at 2.0 g/L while temperature and pH were 30±1°C and 8.3±0.1, respectively. In a typical cycle, complete nitrification occurred at aeration time longer than 6 h. When the aeration time was reduced to 4 h., ～80 % of partial nitritation was achieved. With a further reduction in aeration time to 3 h., nearly 1:1 nitrite/ammonium ratio was yielded. This result revealed that for the reactor design, aeration time determined by feasibility experiments must be considered based on the nitrogen strength in wastewater and biomass concentration in the reactor with dissolved oxygen concentration of ～1.0 mg O₂/L for satisfactory partial nitrification with subsequent processes such as anaerobic ammonium oxidation.     

Analysis of the influence of free ammonia on the accumulation of nitrite in the nitrite nitrification system

Low- and high-concentration nitric wastewater can induce stable nitrite accumulation and realize the nitrification system, with the nitrite accumulation rate between 50% and 90%. In the low-concentration nitrite nitrification system, the average FA concentrations during the period of stable nitrite accumulation remained at 7 to 10 mg/L. In the high-concentration nitrite nitrification system, the nitrogen oxidation activity will not be affected by biomass, the nitrite oxidation activity is related to the system biomass, it is recommended to be measured by FA/MLSS. Keeping the FA sludge load below 0.1 is the precondition of making good nitrite accumulation and nitrogen degradation rate. Nitrite oxidation bacteria cannot be totally eliminated or washed out from the system.     

Correlation between nitrate concentration in groundwater and parameters affecting aquifer intrinsic vulnerability

This paper is the result of a study which was carried out in order to verify if the traditional methods to evaluate the intrinsic vulnerability or vulnerability related parameters, are able to clarify the problem of nitrate pollution in groundwater. In particular, the aim was to evaluate limitations and problems connected to aquifer vulnerability methods applied to nitrate contamination prevision in groundwater. The investigation was carried out by comparing NO₃ ⁻ concentrations, measured in March and November 2004 in the shallow aquifer, and the vulnerability classes, obtained by using GOD and TOT methods. Moreover, it deals with a comparison between NO₃ ⁻ concentrations and single parameters (depth to water table, land use and nitrogen input). The study area is the plain sector of Piemonte (Northern Italy), where an unconfined aquifer nitrate contamination exists. In this area the anthropogenic presence is remarkable and the input of N-fertilizers and zootechnical effluents to the soil cause a growing amount of nitrates in groundwater. This approach, used in a large area (about 10,000 km²) and in several monitoring wells (about 500), allowed to compare the efficiency of different vulnerability methods and to verify the importance of every parameter on the nitrate concentrations in the aquifer. Furthermore it allowed to obtain interesting correlations in different hydrogeological situations. Correlations between depth to water table, land use and nitrogen input to the soil with nitrate concentrations in groundwater show unclear situations: in fact these comparisons describe the phenomenon trend and highlight the maximum nitrate concentrations for each circumstance but often show wide ranges of possible nitrate concentrations. The same situation could be observed by comparing vulnerability indexes and nitrate concentrations in groundwater. These results suggest that neither single parameters nor vulnerability methods (GOD and TOT) are able to describe individually the complex phenomena affecting nitrate concentrations in soil, subsoil and groundwater. In particular, the traditional methods for vulnerability analysis do not analyze physical processes in aquifers, such as denitrification and nitrate dilution. According to a recent study in the shallow unconfined aquifer of the Piemonte plain, dilution can be considered as the main cause for nitrate attenuation in groundwater.     

Correlation between dissolved He concentration and Cl in groundwater at Äspö, Sweden

Tunnel excavation at Äspö Island, Sweden, has caused severe groundwater disturbance, gradually extending deeper into the tunnel as present-day Baltic seawater intrudes through fractures connecting to the surface. However, the paleo-hydrogeochemical conditions have remained in the deep highly saline waters that have avoided mixing. A correlation has been observed between dissolved ⁴He concentration and Cl⁻ ion concentration, measured every two years from 1995 to 2001 at Äspö. Groundwater mixing conditions can be examined by the correlations between 1/Cl, ³⁶Cl/Cl, and ³H concentrations. Subsurface production is responsible for the majority of the ³⁶Cl and excess dissolved ⁴He of interstitial groundwater in fractures. The secular equilibrium ratio of ³⁶Cl/Cl in rock was theoretically estimated to be (5.05 ± 0.82) × 10⁻¹⁴ based on the neutron flux intensity, a value comparable to the measured ³⁶Cl/Cl ratio in rock and groundwater. The degassing crustal ⁴He flux was estimated to be 2.9 × 10⁻⁸  1.3 × 10⁻⁶ (ccSTP/cm²a) using the HTO diffusion coefficient for the Äspö diorite. The ⁴He accumulation rate ranges from 6.8 × 10⁻¹⁰ (for the in situ accumulation rate) to 7.0 × 10⁻⁹ (ccSTP/(g_water · a) considering both ⁴He in situ production and the degassing flux, assuming ⁴He is accumulated constantly in groundwater. By comparing the subsurface ³⁶Cl increase with ⁴He concentrations in groundwater, the ⁴He accumulation rate was determined from data for groundwater arriving at the secular equilibrium of ³⁶Cl/Cl. The ⁴He accumulation rate was found to be (1.83 ± 0.72) × 10⁻⁸ ccSTP/(g_water · a) without determining the magnitude of degassing ⁴He flux.     

江西乐安江流域稻田土重金属累积变化与德兴矿集区关系

对乐安江流域稻田表层土壤中Pb、Cd、Cu、Zn的分布特征进行分析,按照单因子污染指数法和内梅罗综合污染指数法,依据土壤环境背景值标准和国家土壤环境质量标准对乐安江流域稻田土壤的重金属进行评价。结果表明,矿集区上游水稻田土壤重金属综合污染指数等级尚在安全范围内,矿集区周边Cd和Cu的单项污染指数大于1,综合污染指数达到7.82,属于重污染;矿集区下游接近警戒值。研究表明,矿集区矿业开发释放的重金属元素对乐安江中下游流域水稻田土壤的重金属累积具有重要影响。     

江西乐安江流域稻田土重金属累积变化与德兴矿集区关系

对乐安江流域稻田表层土壤中Pb、Cd、Cu、Zn的分布特征进行分析,按照单因子污染指数法和内梅罗综合污染指数法,依据土壤环境背景值标准和国家土壤环境质量标准对乐安江流域稻田土壤的重金属进行评价。结果表明,矿集区上游水稻田土壤重金属综合污染指数等级尚在安全范围内,矿集区周边Cd和Cu的单项污染指数大于1,综合污染指数达到7.82,属于重污染;矿集区下游接近警戒值。研究表明,矿集区矿业开发释放的重金属元素对乐安江中下游流域水稻田土壤的重金属累积具有重要影响。     

Start-up of halophilic nitrogen removal via nitrite from hypersaline wastewater by estuarine sediments in sequencing batch reactor

Nitrogen removal from hypersaline wastewater was successfully started up by inoculating estuarine sediments for 140 days. Efficient ammonia and total nitrogen removal was sustained under specific ammonia loading of 0.016–0.139 kg N/[kg VSS day] in a sequencing batch reactor. Stable nitrite accumulation was observed during nitrification. The specific ammonia consumption rate was higher than the value of freshwater activated sludge and salt-acclimated freshwater activated sludge. With methanol as carbon source, specific nitrite reduction rate of halophilic denitrifiers was much less than the freshwater counterpart. Halophilic activated sludge was characterized as good settling and flocculation prosperity with small floc size and net-like sludge structure. The abundance of ammonia-oxidizing bacteria outnumbered ammonia-oxidizing archaeas in both estuarine sediments and the activated sludge. Nitrifier population was dominated by the halophilic members of genus Nitrosomonas. This study demonstrated the application of mixed halophilic consortia for efficient nitrogen removal, overcoming the limits and difficulties of applying freshwater bacteria for saline wastewater treatment.     

Changes in the characteristics of organic compounds depending on the nitritation efficiency

This study focused on nitritation reactions for the removal of highly concentrated nitrogen from water recycled by a MWTP (Municipal Wastewater Treatment Plant) for the preparation of effluent standards which will be strengthened. To examine the changes that occur during a nitritation reaction with a variety of SRT operations when inducing a stable nitritation reaction, a reactor was operated on a laboratory scale in this study. Digestion tank supernatant flowed into a laboratory-scale reactor and organic matter in the effluent under various operation conditions was classified into four types according to ASM standards using the test known as the OUR (Oxygen Uptake Rate)-test. Most organic matter in the digestion tank supernatant appeared to consist of mainly the S_I component out of non-biodegradable organic matter. During the operation period of the effluent in the laboratory-scale reactor, if a nitritation reaction occurs in a stable manner, most biodegradable organic matter is removed, consisting of mainly the S_I component, like the influent. Particularly, nitrogen was removed after the S_S was removed from the organic matters. Moreover, through a multiple correlation analysis between the operation results from a laboratory-scale reaction bath and the organic composition of the effluent, a method to predict the organic composition of effluents that relies on the operation result of the effluent is proposed.     

Correlation between joint orientation and geophysical stresses in a test area on the Canadian Shield

SummaryCorrelation Between Joint Orientation and Geophysical Stresses in a Test Area on the Canadian Shield It is contended that the orientation of the geophysical stress field in an area can be deduced from an analysis of the orientation of the joints which it has produced. As a test area, a reasonably homogeneous region of the Canadian Shield in the vicinity of Three-Mile-Lake in Ontario (roughly lat. 45° 10N and longitude 79° 25W) was chosen for analysis. It was found that the stresses were indeed homogeneous over an area of about 10 × 4 km with the exception of a small area which also shows petrographic and geomorphic peculiarities. Thus, local tectonic anomalies can immediately be recognized in the joint patterns.

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ZusammenfassungKorrelation zwischen der Lage von Klüften und dem geophysikalischen Spannungsfeld in einem Testgebiet im kanadischen Schild Es wird die Hypothese aufgestellt, daß die Hauptachsenrichtungen des geophysikalischen Spannungsfeldes aus der Lage der von ihm verursachten Klüfte abgeleitet werden kann. Um die Hypothese zu prüfen, wurde ein verhältnismäßig homogenes Gebiet des kanadischen Schildes in der Nähe vom Three-Mile-See in Ontario (ungefähr 45° 10N Breite und 79° 25W Länge) ausgewählt. Es wurde festgestellt, daß das abgeleitete Spannungsfeld über ein Gebiet von 40 km² tatsächlich homogen ist, mit Ausnahme einer kleinen Fläche, welche auch petrographische und geomorphologische Anomalien aufweist. Es können daher tektonische Anomalien sofort in den Klüftediagrammen erkannt werden.

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RésuméCorrelation entre l'orientation des clivages et les contraintes tectoniques dans une région d'épreuve du bouclier Canadien L'hypothèse est maintenue que l'orientation du champ des contraintes tectoniques peut être déduite par une analyse de l'orientation des clivages qu'il a produite. Comme région d'épreuve, une région à peu près homogène du bouclier Canadien dans le voisinage du Lac-des-Trois-Miles (45° 10N, 79° 25W) a été choisie. Il est démontré que les contraintes sont actuellement homogènes dans une région de 40 km², y exceptée une petite région où l'on observe aussi des péculiarités pétrographiques et géomorphologiques. Ainsi, les anomalies tectoniques locales peuvent être reconnues immédiatement dans les dessins du clivage.

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With 14 Figures     

Correlation method of detecting and measuring weak signals (Asynchronous accumulation)

A method of asynchronous accumulation of signals is described in this pamphlet, its theoretical basis is given and circuit diagrams of various modifications of such devices are cited together with the results of their application in radar, radio-astronomy, geophysics and other fields of science and engineering. Systems for seismic detection and for deep probing of the earth's core are described in detail. — V. S. Voyutskiy.     

Ammonia adsorption and nitritation in sediments derived from the Three Gorges Reservoir,China

The influences of suspended particles (SPs) on NH₄ ⁺ adsorption and nitritation occurring in the water system of the Three Gorges Reservoir (TGR) were evaluated in this study. The results indicated that the adsorption of NH₄ ⁺ was significantly affected by the SPs concentration under the conditions typically present in the TGR. The amount of ammonia adsorbed per unit weight of suspended particles was inverse proportional to the concentration of suspended particles. However, the influences of the particle size and the organic matter concentration existing in SPs were insignificant under the experimental conditions. The effects of suspended particles on nitritation were determined by the use of ammonia-oxidizing bacteria (AOB) strain SW16, identified as Nitrosomonas nitrosa, which was isolated from sediment samples of the TGR. Suspended particle concentration in water–sediment solution played an important role in the nitritation process. The rate of nitritation enhanced with the increase of the suspended particle concentration. It was found that the critical factor controlling ammonia oxidizing rate was the AOB biomass resulting from the AOB growth rate. Moreover, results demonstrated that both particle size and organic matter content showed little effect on the nitritation process under the experimental conditions.     

论油气成藏与金属成矿的关系及综合勘探

从油气藏及金属矿藏的来源、运移、成藏/成矿等方面对油气成藏和金属成矿之间的关系进行了论述,指出油气藏和沉积金属矿藏均来自于相同的烃源岩/矿源层。一些金属(铀、黄铁矿等)的存在,有可能对有机质向烃类的转化起到了积极的催化作用,而烃类中的有机酸对金属元素具有溶解、螯合作用,有利于金属元素随烃类和成矿流体的析出。烃类和成矿流体在水-油-岩共存体系,在近乎相同的运移机制和路径中,能够一起溶解、萃取其路径上的金属元素,有利于金属元素的运移。油气与成矿流体可以在圈闭中聚集、成藏或者由于物理化学条件的变化,金属矿物独立沉淀成矿。油气与金属的成藏/成矿在时间和空间上也具有某些相似性。因此油气成藏和金属成矿具有非常密切的关系,有利于对二者进行综合勘探和利用,具有非常重要的现实意义。     

塔里木与四川盆地震旦系—寒武系油气成藏条件对比与启示

塔里木盆地与四川盆地是中国海相深层6000 m以深油气勘探的重点地区,已发现多个深层超深层大中型油气田,而且有一批重点探井见到了良好的油气显示,预示着该领域有巨大的勘探潜力.本文从沉积建造和后期构造改造两个方面对比了塔里木盆地和四川盆地震旦系寒武系油气成藏条件,并依据勘探与研究进展,提出了深层—超深层油气勘探建议.研究...     

Correlation between length and offset in strike-slip faults

Strike-slip faults in continental crust are shown to exhibit non-linear positive correlation between length and offset. This correlation can be empirically explained as the combined effect of the changes in the growth rates of offset and length during the time of tectonic activity of a fault.     

Correlation between geochemical environments and controlling factors in the metallation of porphyrins

Experimental study on metallation of tetrapyrroles in biphasic systems showed that complexation with metal cations of the first transition series is a feasible under chemical environments similar to the naturally occurring ones. The metal transport from the aqueous media to the organic, which is a novel approach using naturally occurring fatty acids hydroxy aromatic compounds and thiols, is demonstrated. Selectivity between Ni²⁺ and VO²⁺ complexation is achieved under sulfurous rich conditions. The kinetic implications are discussed in view of their geoenvironmental applicability.     

浅析张家口地区降水与地下水的相关性

地下水埋深发展趋势与当地降水情况息息相关,但因诸多因素影响,地下水埋深与降水的关系并不是必然性。张家口地区水资源的污染和短缺问题已越来越严重化,通过分析张家口地区降水与地下水相关关系,提出保护水资源的第一个举措则是要充分做好地下水资源监测工作,控制人为因素的影响,特别是地下水开采量的合理安排和控制,对研究地下水生态系统有着重大意义。     

Relationships between DOC concentration,molecular size and fluorescence properties of DOM in a stream

The patterns of dissolved organic matter (DOM) fluorescence properties were examined in a Precambrian shield stream over a seven-month field study. Unique spatial and temporal patterns of simultaneous changes were observed in dissolved organic carbon concentration (DOC), humic-like fluorescence intensity, maximum excitation and emission wavelengths and fluorescence index (the ratio of the emission intensity at a wavelength of 450 nm to that at 500 nm at an excitation wavelength of 370 nm). The spatial change indicates the alteration of DOM along the length of the stream, and temporal change corresponded to a drought event in August. In contrast to humic-like fluorescence, the protein-like fluorescence shows considerable variability, suggesting its ephemeral nature. There were strong relationships between humic-like fluorescence intensity, fluorescence index, maximum Ex/Em wavelengths, DOC concentration and molecular size of DOM. This study has significant implications to the understanding of the nature and biogeochemical cycling of DOM.     

石西油田石炭系水动力特征及其与含油性关系

利用油层流体的物化参数对油藏所处的水动力环境、油气运移方向及断层的封闭性进行了分析判断。研究结果表明，石西油田供水区在石007井东断裂西侧，并且由西向东渗人；石007井东断裂具有良好的封闭性，断裂东侧较西侧封闭，水动力也较西侧弱，使东断块油气较西侧易于保存，东断块含油显示也明显好于西断块。石西油田原油的物理性质与水动力环境有一定关系，但在平面上原油性质的变化主要受油气运移层析效应的控制。西断块水动力强，原油性质变化速率大；东断块水动力弱，原油性质变化速率小。油气运移方向为东、东北向西、西南，原油性质也沿该方向降低。     

Correlation between nickel and sulfur abundances in Orgueil phyllosilicates

Sympathetic variations in nickel and sulfur abundances, on a scale of micrometers, in Orgueil phyllosilicates apparently reproduce similar correlations among matrices of different carbonaceous chondrites (McSween and Richardson, pp. 1145–1161, this issue). In Orgueil this effect probably results from aqueous alteration of a NiSi-bearing phase on the parent body.     

赣皖边境地区青白口纪地层划分与对比

1:5万区调填图中系统调研了江西省内都昌县马涧桥、波阳县燕窝一带新发现的青白口纪地层岩石组合与层序、岩相特征,获得部分微古植物化石及847±38Ma的同位素测年数据,重新厘定并新建马涧桥组,据其特征认为可与毗邻的皖南青白口纪地层对比。四堡运动后,本区与皖南都曾经历过裂陷时期,具有相同的构造背景。