间歇曝气A2/C氧化沟工艺处理城市污水中试研究

为降低氧化沟工艺的运行成本,研究了连续进水间歇曝气缺氧(Anoxic)-厌氧(Anaerobic)-Carrousel氧化沟(A2/C)工艺.采用A2/C氧化沟模型运用连续进水间歇曝气模式对城市污水处理进行了研究.结果表明,增强外源反硝化是提高脱氮效率的关键.在一定范围内加大回流比,能够提高间歇频率,减小各污染指标在反应系统中的积累.在曝气1 h,停止曝气3 h,回流污泥比200%的模式下(模式Ⅱ),出水CODcr,NH4 -N和TN分别为40～50 mg·L-1、3.0～5.7 mg·L-1和10.2～12.5 mg·L-1.3个模式在1个周期内平均曝气量分别为连续曝气过程的66%、50%、44%.模式Ⅱ中在线监测仪表数据分析显示,曝气过程中出现NH4 -N氧化的终点--在pH曲线上表现为出现"氨谷",若利用在线监测仪表在曝气阶段采用自动控制,则可避免过量曝气.采用实际城市污水,应用中试试验模型,能够为实际生产提供重要技术参数,为原有氧化沟工艺技术改造提供支持.     

天津市经济—环境系统的物质流分析

利用物质流分析工具对天津市经济—环境系统中的物质流进行了分析,分析结果表明:2004年天津市的物质需求总量达到8.68亿t,且增长趋势明显,其中基础设施建设对环境造成了较大扰动,进口物质大于出口物质;城市环境容量总体处于饱和状态,水体污染严重;物质消耗强度不断增长,资源的利用效率处于较低水平。最后,针对存在的问题,提出相应的措施和建议。     

Applications of Venturi Principle to Water Aeration Systems

The concentration of dissolved oxygen is an important indicator of water quality because aquatic life lives on the dissolved oxygen in the water. Aeration can increase dissolved oxygen when levels become deficient. Hydraulic structures can significantly improve dissolved oxygen levels by creating turbulent conditions where small air bubbles are carried into the bulk of the flow. Recent researches have focused on developing measurement and predictive techniques for oxygen transfer at hydraulic structures to maintain and enhance water quality. However, reviewing existing studies on aeration performance of hydraulic structures, it seems that there are not too many studies on venturi aeration. The present paper shows applications of venturi principle to water aeration systems. The aeration characteristics of venturi nozzle, venturi conduit and venturi weir are analyzed. The results indicate that venturi aeration might contribute significantly to air entrainment and aeration efficiency. Therefore, venturi device can be used as highly effective aerator in aeration processes.     

猪粪混合堆肥过程中重金属含量的变化

在猪粪混合堆肥中，采用不同的通风方式和填充料，分析该过程中重金属总量和DTPA提取的重金属含量变化。结果表明，通过猪粪混合堆肥，重金属总量不会降低，但重金属生物有效性可降低；在猪粪与木屑混合堆肥中，加入树叶或鸡粪均能显著降低重金属的生物有效性，强制通风 机械翻堆比单一机械翻堆更能降低重金属的生物有效性。     

Vocalizations and courtship intensity correlate with mounting success in marginated tortoises<Emphasis Type="Italic"> Testudo marginata</Emphasis>

The courtship and mounting behaviour of tortoises is elaborate, and based on a multiple signalling system involving visual, olfactory and acoustic signals. Vocalizations related to mounting seem to be particularly significant because tortoises vocalize mainly at this time. Vocalizations and courtship behaviour may be costly for males, and if these costs increase differentially for different males, then the potential exists for vocalizations and displays to reveal male individual quality. In this correlative study, we analysed relationships between male mounting success and morphological and behavioural traits, particularly acoustic signals, exhibited by male marginated tortoises (Testudo marginata) during courtship, in a group of 94 individuals breeding in semi-natural enclosures. For each male, we estimated general body condition, courtship intensity and mounting success; calls of mounting males were recorded and four sonagraphic features were measured. Calls differed significantly among males, and two features varied according to body condition. Male mounting success significantly increased according to the male/female size-ratio, suggesting the existence of a size-based assortative mating. Mounting success was also highly correlated with courtship intensity, measured as number of bites and rams given to females before mounting, and with number of calls emitted during mounting. Finally, mounting success was negatively related to call duration. To our knowledge, this is the first study in which features of tortoise vocalizations are shown to convey reliable information about male quality in socio-sexual contexts.Communicated by T. Czeschlik     

Agricultural land-use change and ash (<Emphasis Type="Italic">Fraxinus excelsior</Emphasis> L.) colonization in Pyrenean landscapes: an interdisciplinary case study

Changes in agricultural land use are responsible for significant modifications in mountain landscapes. This study is part of an interdisciplinary research on the processes and consequences of spontaneous afforestation of Pyrenean landscapes by ash, and the possibilities for its management. We address the relationships between vegetation dynamics and land-use change from the combination of an agricultural study of change in farm management and an ecological study of grassland colonization by ash. In the framework of a village case study, we characterized parcels management and land-use histories, and analyzed the dynamics of the composition of grassland vegetation communities. From a joint analysis of the results obtained in each discipline, we discuss the limitations and complementarities of the two approaches for the interdisciplinary assessment of the afforestation process.     

恶臭污染及其治理技术

介绍了恶臭物质的来源、对人体的危害及恶臭强度分级方法；综述了常用的恶息物质处理方法。     

A MODEL FOR PREDICTING LAKE SEDIMENT OXYGEN DEMAND FOLLOWING HYPOLIMNTETIC AERATION1

ABSTRACT: Hypolimnetic aeration is a widely used technique for lake restoration and fisheries enhancement. However, system design still depends on application of “safety factors” to observed oxygen demand rates, in large part because actual oxygen demand may be greater after aeration than before. Laboratory incubations of sediment show that sediment oxygen demand (SOD) rates follow mixed order kinetics, with an initial period of zero order reaction, followed by first order kinetics. The transition from zero to first order kinetics may correspond to the transition from laminar to turbulent flow. This suggests that SOD reaction kinetics are governed by thickness of the diffusive sublayer adjacent to the sediments. Therefore, zero and first order reaction regions correspond with oxygen diffusion limitation and substrate limitation, respectively. Such a mechanism would account for the induced oxygen demand observed following hypolimnetic aeration and would reconcile differences in SOD reaction orders noted in the literature. This paper describes development of equations based on laboratory SOD incubations for predicting induced oxygen demand following hypolimnetic aeration.     

PREDICTING PEAK STREAM FLOW FROM AN UNDISTURBED WATERSHED IN THE CENTRAL APPALACHIANS1

ABSTRACT: Data from a small forested catchment were used to model peak stream flow as a function of basic hydrologic variables associated with 112 rain storms. Rainfall depth and initial stream flow rate accounted for 87.1 percent of peak flow variability. Forty expressions of rainfall intensity (describing both the temporal sequence of intensity for 20 equal storm intervals, and maximum intensity for 20 separate interval lengths) were used in an attempt to improve the predictability of basic models. None of the intensity parameters improved predictability by as much as 2 percent, apparently because the most intense rainfall bursts generally occurred near the beginning of storm periods. Mean rainfall intensity for entire storms was generally as effective as any of the shorter interval intensities, and its use helped to linearize the relationship between peak flow and rainfall depth and duration.     

TURBULENCE MEASUREMENT OF A FLOW WITH SUSPENDED SOLID PARTICLES1

ABSTRACT: Success in measuring turbulence in water has been achieved by replacing the hot-wire probe by the hot-film probe. Accordingly, these results have greatly increased knowledge and understanding of hydromechanics. However, there are few published measurements of turbulent properties of flow with suspended solid particles. With this in mind, the authors conducted measurements of turbulent properties of flow with suspended solid particles by using a quartz-coated, wedge-shaped hot-film probe. Turbulent intensities and macroscale of eddy change in the flow with suspended solid particles on a movable bed is discussed.