水准测量允许误差的确定

本文主要依据误差传递理论,对水准测量成果精度进行了分析,从而得出了水准测量允许误差的理论根据。     

Determination of the dynamics of the odour release from a pig house, using an electronic odour sensor.

The widely fluctuating operating conditions in pig husbandry, due to climatic and biological changes (changes in temperature and air flowrate between day and night, as well as between summer and winter, increasing animal mass during the fattening process, etc.) exert a significant influence on the amount of actual odour emission. The project presented here comprised the measurement of seasonal (fattening course), daytime-related, and short-term (feeding) dynamic effects of odour release, as well as the identification of potential factors which influence the amount of odour emitted. In parallel with "classic" olfactometry, an electronic odour sensor with a chemosensor array of ten metal oxide sensors was employed. The highest odour emissions are measured on hot summer days, while the lowest emissions were determined on cold winter days. On the one hand, the sensor signals of the electronic odour sensor exhibited considerable differences on days with large volume flow alterations. On the other hand, continuous measurement with the electronic odour sensor allowed changes in the gas- and odorant composition of the exhaust air during feeding times to be shown. From the measurement results, recommendations for odour sampling, the consideration of seasonal odour emission fluctuations, and the use of electronic odour sensors for the evaluation of odour emissions have been derived.     

松嫩平原河流水位方程的确定及应用

本文从松嫩平原的特定水文地质条件出发,分析了该地区的地下水和地表水水位变化关系及规律,利用Surfer软件采集主要河流各水文站水位数据及河流各点坐标数据,再利用Excel绘制河流某一时刻的水位(H)-河长(L)曲线,并得到四归方程.通过河流H-L方程,合理地插补没有观测点处的河流水位,使绘制的松嫩平原的潜水等水位线图与实际流场更好地拟合,从而为地下模拟系统(GMS)中建立水文地质结构模型奠定了良好的基础.     

察尔森水库汛限水位过程线的确定

本文针对察尔森水库及其所处流域的实际情况,应用模糊水文学理论方法推求出水库汛限水位过程线,解决了水库在实际运行中难以实现分期抬高汛限水位期望值的关键问题,进一步增加了水库蓄水量和汛后蓄满的几率,更好地发挥了水库兴利效益。     

沙坪水电站正常高水位的确定

沙坪水电站正常高水位的确定主要考虑天然落差的利用、库区淹没、综合利用等因素，并按全面的经济评价判据来确定。表2个。     

粒状活性炭在管道分质供水口感改善中的作用研究

口感是评价管道分质供水质量的一项关键指标,它直接影响消费者对管道分质供水的接受程度。研究了影响管道分质供水口感的主要因素及粒状活性炭对口感改善所起的作用。结果表明,净水中余氯浓度、TOC含量及VOCs含量均会对净水口感产生影响;粒状活性炭过滤可有效降低管道分质供水中净水余氯浓度、TOC与VOCS含量,明显改善净水口感,而对其他水质指标无不良影响。结合试验结果与工程实例,提出了应用粒状活性炭改善管道分质供水口感的技术参数,并建议采用粒状活性炭过滤器作为管道分质供水的终端过滤。     

Treatment of taste and odor material by oxidation and adsorption.

Massive blooms of blue-green algae in reservoirs produce the musty-earthy taste and odor, which are caused by compounds such as 2-MIB and geosmin. 2-MIB and geosmin are rarely removed by conventional water treatment. Their presence in the drinking water, even at low levels (ng/L), can be detected and it creates consumer complaints. So those concentrations have to be controlled as low as possible in the drinking water. The removals by oxidation (O3, Cl2, ClO2) and adsorption (PAC, filter/adsorber) were studied at laboratory and pilot plant (50 m3/d) to select suitable 2-MIB and geosmin treatment processes. The following conclusions were derived from the study. Both of the threshold odor levels for 2-MIB and geosmin appeared to be 30 ng/L as a consequence of a lab test. For any given PAC dosage in a jar-test, removal efficiencies of 2-MIB and geosmin were increased in proportion to PAC dosage and were independent of their initial concentration in raw water for the tested PAC dosages. In comparison of geosmin with 2-MIB, the adsorption efficiency of geosmin by PAC was superior to that of 2-MIB. The required PAC dosages to control below the threshold odor level were 30 mg/L for geosmin and 50 mg/L for 2-MIB at 100 ng/L of initial concentration. Removal efficiencies of odor materials by Cl2, ClO2, and O3 were very weak under the limited dosage (1.5 mg/L), however increased ozone dosage (3.8 mg O3/L) showed high removal efficiency (84.8% for 2-MIB) at contact time 6.4 minutes. According to the initial concentrations of 2-MIB and geosmin, their removal efficiencies by filter/adsorber differed from 25.7% to 88.4%. For all those, however, remaining concentrations of target materials in finished waters were maintained below 30 ng/L. The longer run-time given for the filter/adsorber, the higher the effluent concentration generated. So it is necessary that the run-time of the filter/adsorber be decreased, when 2-MIB or geosmin occurs in raw water.     

Determination of fragrances at ng/L levels using CLSA and GC/MS detection.

Polycyclic and nitro musks and two fragrances (Acetyl cedrene and Amberonne) have been determined and quantified in influent and effluent waste water, river water and tap water samples from different European countries by closed loop stripping analysis (CLSA) as a method of preconcentration and GC/MS operating in the SIM mode. Limits of detection; precision expressed as repeatability and reproducibility relative standard deviations of the method; matrix effects and the estimation of the uncertainty have been evaluated. All samples contained different musks at ng/l levels being the polycyclic musks Galaxolide and Tonalide and both fragrances, Amberonne and Acetyl cedrene the most abundant. Removal of these main compounds is achieved partially in all waste water treatment plants studied. These results suggest the importance of studying and controlling the presence of these ubiquitous environmental compounds in water systems.     

Optimal performance of an immersed membrane bioreactor equipped with a draft tube for domestic wastewater reclamation.

One of the options to prevent membrane fouling is to implement air lifting that can improve the cake removal from the membrane surface. This study presents the results of tests that were carried out at the Institutes for Desert Research, Kiryat Sde-Boker, Israel, and focused on the influence of hydrodynamic conditions on fouling in a pilot-scale immersed membrane bioreactor (IMBR) using a hollow fiber membrane module of ZW-10 (Zenon Environmental, Canada) under ambient conditions. In this system, the cross-flow velocities across the membrane surface were induced by one conical and four cylindrical draft-tubes. The relationship between the crossflow velocity and the aeration intensity, the influence of the crossflow on fouling rate under various hydrodynamic conditions were investigated and optimal operating conditions were obtained. Optimal operating conditions were reached during the long-term experiment period (70 days) for the treatment of domestic wastewater. The system was stable without external chemical cleaning. The results showed that the permeate was of high quality, and the removal of COD and BOD was 94.0% and 98.8%, respectively.The crossflow near the membrane surface reveals a major contribution for minimizing membrane fouling, and could offer guidelines for future design of similar systems.     

西江河床式电站尾水位的确定

在低水头大流量的河床式电站设计中,如何确定尾水位是值得重视和研究的新课题。桓仁西江电站可行性研究成果表明,按通常作法,直接采用大河稳定水位作为电站尾水位是不适宜的。本文就如何确定西江电站尾水位做进一步探讨和论述。     

Determination of the level of seismic danger and design seismic loads for large hydrotechnical structures

A local network of sensitive high-accuracy seismological stations has to be created for seismological observations near a hydrotechnical structure and on the banks of the storage reservoir. The layout of the network is chosen with allowance for the configuration of the reservoir and for the location of the seismogenerating zone relative to the structure. __________ Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 11, November 2005, pp. 16–26.     

Determination of reaction rate constants for phenol oxidation using SnO2/Ti anodes coupled with activated carbon adsorption in the presence of TiO2 as catalyst

Series of experiments for phenol degradation with assistance of TiO2 catalyst at pH of 6.5 and temperature of 25 degrees C were conducted using a lab-scale electrochemical reactor constructed in our laboratory. According to the results, at the presence of the TiO2 catalyst the removal of phenol was increased and first-order kinetics could describe the evolution of phenol concentration. For inspecting the relationship between rate constants and dosage of TiO2, two possible kinetics were proposed in this study. Contrasted to the abundant experimental data, a reasonable kinetics was obtained for the estimation of phenol concentration effluent during continuous flow of raw wastewater, especially when the TiO2 dosage was less than 0.5g L(-1). The model obtained from these experiments could employed for the calculation of rate constants at different TiO2 dosage and the necessary dosage of catalyst when a discharge standard was designed.     

利用水量平衡法确定白洋淀最低补水水位的探讨

近年,白洋淀多次面临干淀危机,"引黄济淀"等应急工程措施进行人为补水已经成为现实且运行多年。本文以出、入淀水量为零为前提,依据充分的水文资料和文献成果,采用水量平衡法动态地进行逐月分析计算,得到白洋淀枯水期的理论退水水位过程,从而取得枯季任一时间的最低补水水位,以此作为调水决策依据。选取典型代表年的部分月份实测资料进行了对比分析验证,并指出了该演算结果存在的不足。     

弯肘型尾水管非定常涡旋流动数值模拟

本文采用有限体积法求解用代数雷诺应力模型封闭的雷诺平均N—S方程组,对湖北清江隔河岩水电站l号发电机组的尾水管,在部分负荷工况运行时的非定常涡旋流动进行了数值分析。结果表明,在水轮机部分负荷运行,特别是负荷为40％左右时,尾水管内形成了明显的旋转涡带。数值模拟得到的尾水管中压力脉动的频率,与湖北中试所在隔河岩进行测试的结果基本一致。     

Suppression of vortex rope oscillation and pressure vibrations in Francis turbine draft tube using various strategies

The vortex rope usually occurs in the draft tube of the Francis turbine operated under part-load conditions,to induce strong low-frequency pressure vibrations,a...     

Designing and performing experiments for model calibration using an automated iterative procedure.

Optimal experimental design for parameter estimation involves complex mathematical and practical steps in order to obtain a model with sufficiently accurate parameters. This paper proposes a methodology where user interaction is only required at the beginning of the experimental design procedure. All subsequent steps are carried out automatically, including: (1) finding the optimal experiment, (2) performing the experiments in practice, and (3) recalibrating the model. A software extension to an existing modelling and simulation package which performs this automatic procedure is also presented. Finally an illustration for the calibration of a one-step nitrification model using respirometric data is given. In this case, the application of the proposed procedure resulted, after three iterations, in considerably better confidence intervals on the parameter estimates, within the desired boundaries.     

Development of a coliforms monitoring system using an enzymatic fluorescence method.

A coliforms monitoring system in treated effluent of a wastewater treatment plant has been developed. In order to achieve rapid monitoring within 1 hour, an enzymatic fluorescence method without a culturing process was introduced to this system. It converts the increase rate of fluorescence intensity as enzymatic activity into the number of coliforms instead of converting fluorescence intensity itself. A flow injection analysis is used in this system for automatic measurement. Moreover, it is equipped with the pre-filtering unit to remove the interfering substances in the suspended solids causing deterioration in measurement precision. The good relationship (correlation coefficient of 0.90) between the obtained values using this system and the analysed values using the conventional direct counting method was observed in a test at an existing wastewater treatment plant.     

Optimal maintenance of constructed wetlands using an environmental decision support system.

Constructed wetlands (CWs) are artificial wastewater treatment systems appropriate for small communities because of their affordability, operability and reliability. These qualities are true whenever CWs are designed and constructed properly, and as long as the necessary operation and maintenance procedures are carried out correctly. Experience shows that the operation and maintenance procedures, and the frequencies with which these procedures are carried out, differ from one CW to another. With this in mind, and along with a projected increase in CWs in Catalonia, the Catalan Water Agency (Agència Catalana de l'Aigua) has developed an Environmental Decision Support System (EDSS) which proposes guidelines for monitoring and maintenance, according to the characteristics of each CW. This EDSS was developed following a methodology based on five steps: (i) problem analysis; (ii) collecting data and knowledge acquisition; (iii) model selection; (iv) model implementation and (v) validation. This paper describes the methodology followed to build the decision support system and presents some examples of the information provided by this EDSS.     

Co-removal of hexavalent chromium through adsorption during copper precipitation.

A systematic study was conducted to assess the mechanisms involved in the co-removal of hexavalent chromium during chemical precipitation of divalent copper. Batch tests were used to assess the precipitation phenomena in both pure copper solutions and also mixed copper-Cr(VI) solutions with progressive addition of sodium carbonate to increase pH and induce precipitation. It was found that the co-removal of Cr(VI) was caused by two distinct mechanisms: coprecipitation of copper with Cr(VI) at pH 5.0 to 5.2, leading to the formation of CuCrO4 precipitates. Once the fine crystallites of CuCrO4 were formed, the test solution became heterogeneous and this accelerated the production of copper-carbonate precipitates, mainly in the form of CuCO3 Cu(OH)2, at pH 5.2 to 6.2. The latter precipitates were negatively charged at pH below 7.5, and thus they were able to adsorb a considerable amount of the remaining chromate ions [HCrO4- and CrO4(2-)]. The extent of adsorption depended on both pH and surface loading. Besides electrostatic attraction, ligand exchange was also found to play some role. Maximum adsorption occurred at pH 6.5. When pH was raised to 10.0, approximately 25-30% of the adsorbed chromium could become desorbed due to a surface charge reversal on the adsorbent.     

Evaluation of an optimal fill strategy to biodegrade inhibitory wastewater using an industrial prototype discontinuous reactor.

This work presents the results and discussions of the application of an optimally controlled influent flow rate strategy to biodegrade, in a discontinuous reactor, a synthetic wastewater constituted by 4-chlorophenol. An aerobic automated discontinuous reactor system of 1.3 m3, with a useful volume of 0.75 m3 and an exchange volume of 60% was used. As part of the control strategy influent is fed into the reactor in such a way as to obtain the maximal degradation rate avoiding inhibition of microorganisms. Such an optimal strategy was able to manage increments of 4-chlorophenol concentrations in the influent between 250 and 1000 mg/L. it was shown that the optimally controlled influent flow rate strategy brings savings in reaction time and flexibility in treating high concentrations of an influent with toxic characteristics.