Hydraulic management of a soil moisture controlled SDI wastewater dispersal system in an Alabama Black Belt soil

Rural areas represent approximately 95% of the 14000 km(2) Alabama Black Belt, an area of widespread Vertisols dominated by clayey, smectitic, shrink-swell soils. These soils are unsuitable for conventional onsite wastewater treatment systems (OWTS) which are nevertheless widely used in this region. In order to provide an alternative wastewater dosing system, an experimental field moisture controlled subsurface drip irrigation (SDI) system was designed and installed as a field trial. The experimental system that integrates a seasonal cropping system was evaluated for two years on a 500-m(2) Houston clay site in west central Alabama from August 2006 to June 2008. The SDI system was designed to start hydraulic dosing only when field moisture was below field capacity. Hydraulic dosing rates fluctuated as expected with higher dosing rates during warm seasons with near zero or zero dosing rates during cold seasons. Lower hydraulic dosing in winter creates the need for at least a two-month waste storage structure which is an insurmountable challenge for rural homeowners. An estimated 30% of dosed water percolated below 45-cm depth during the first summer which included a 30-year historic drought. This massive volume of percolation was presumably the result of preferential flow stimulated by dry weather clay soil cracking. Although water percolation is necessary for OWTS, this massive water percolation loss indicated that this experimental system is not able to effective control soil moisture within its monitoring zone as designed. Overall findings of this study indicated that soil moisture controlled SDI wastewater dosing is not suitable as a standalone system in these Vertisols. However, the experimental soil moisture control system functioned as designed, demonstrating that soil moisture controlled SDI wastewater dosing may find application as a supplement to other wastewater disposal methods that can function during cold seasons.     

Experimental study of recirculating flows generated by lateral shock waves in very large channels

Due to the lack of data on hydraulic-jump dynamics in very large channels, the present paper describes the main characteristics of the velocity field and turbulence in a large rectangular channel with a width of 4 m. Although a hydraulic jump is always treated as a wave that is transversal to the channel wall, in the case of this study it has a trapezoidal front shape, first starting from a point at the sidewalls and then developing downstream in an oblique manner, finally giving rise to a trapezoidal shape. The oblique wave front may be regarded as a lateral shockwave that arises from a perturbation at a certain point of the lateral wall and travels obliquely toward the centreline of the channel. The experimental work was carried out at the Coastal Engineering Laboratory of the Water Engineering and Chemistry Department of the Technical University of Bari (Italy). In addition to the hydraulic jump formation, a large recirculating flow zone starts to develop from the separating point of the lateral shock wave and a separate boundary layer occurs. Intensive measurements of the streamwise and spanwise flow velocity components along one-half width of the channel were taken using a bidimensional Acoustic Doppler Velocimeter (ADV). The water surface elevation was obtained by means of an ultrasonic profiler. Velocity vectors, transversal velocity profiles, turbulence intensities and Reynolds shear stresses were all investigated. The experimental results of the separated boundary layer were compared with numerical predictions and related work presented in literature and showed good agreement. The transversal velocity profiles indicated the presence of adverse pressure gradient zones and the law of the wall appears to govern the region around the separated boundary layer.     

Hypsographs: Basic tools for lake management and monitoring

Hypsographs are graphic depictions of the vertical distributions of volumes or masses of water in lakes, ponds, or reservoirs. Quantitative limnological science or engineering must use a hypsograph, or a more complex equivalent system, to undertake calculations of water constituent concentration data by mathematical weighting. Construction of the graph is simple and described. Exemplary uses of the hypsograph are presented.     

以最经济输水为原则 调整高压输水泵及工艺

简这了炼油厂更新高压输水泵，调整输水工艺、降低输水成本的方法。     

水力负荷对辐流式初沉池污染物去除效果的影响

以沉砂池出水为原水,在沉淀试验研究颗粒截留速度u0基础上,通过动态试验考察水力负荷对辐流式初沉池污染物去除效果的影响。研究结果表明无机悬浮固体(FSS)分离和总悬浮固体(TSS)高效去除的颗粒截留速度u0分别为0.025 m/min和0.05 m/min。由于泥层截留作用,水力负荷qA在46.3 m3/(m2.d)时,辐流式初沉池污染去除最高效,TSS、总氮(TN)和总磷(TP)去除率分别达到81%,23%,59%。     

量纲分析对污水近区初始稀释度变化规律的探讨

在上海合流污水二期工程白龙港排放口水力模型试验基础上，根据模型实验的大量数据，采用量纲分析方法对近区初始稀释度的变化规律进行了探讨，得出了描述该区域初始稀释度变化规律的半理论半经验公式，可为实际排海工程的设计提供依据。     

流化BAF处理生活污水的研究

曝气生物滤池是一种新型的水处理技术。选择海绵块作为曝气生物滤池的填料,研究了此种海棉块在曝气生物滤池内的挂膜效果．讨论了不同的水力停留时间对曝气生物滤池处理生活污水效果的影响。结果表明,水力停留时间对处理效能有较明显的影响．缩短水力停留时间使反应器对COD、氨氮和悬浮物的去除率下降。     

Framing Dynamics and Political Gridlock: The Curious Case of Hydraulic Fracturing in New York

‘Fracking’ was on New York's agenda since 2008, yet no decision was made about it until late 2014. The gridlock is an intriguing puzzle given that the Marcellus shale is considered a ‘world class’ energy supply, and development has been aggressive in other US states. While policy scholars typically conceptualize gridlock as policy stability, this paper examines it as a dynamic process by which competing discourse coalitions engage in interactive framing processes that (re)structure the discussion. This suggests that the interaction between contending coalitions influences gridlock. Yet, we lack knowledge about interactive framing between competing coalitions during policy controversies. Our main finding is that a central mechanism of gridlock is the production of conflict through interactive framing dynamics that deny a shared discursive space capable of ushering in a consensus, or reasoned agreement. In New York, this contest evolved from a policy consensus about the economic benefits of fracking to policy negotiation that incorporated environmental threats, and to prolonged policy controversy in which competing discourse coalitions contested notions of fracking in relation to energy production, environmental protection, public health, economic development, and governance. While a ban has been instituted, the failure to bridge discourse coalitions suggests that controversy will persist unless meaning disputes are resolved.     

准噶尔盆地西北部引水工程建设运行的生态环境效益评估

准噶尔盆地西北部引水工程的建成和运行,对工程沿线区域土地资源的利用方式产生了深远的影响,也改变了该区域以土地资源为载体的生态系统的结构和生态环境的价值。以Constanza等人对全球各类生态系统单位面积服务价值的测算为依据,根据准噶尔盆地西北部引水工程沿线影响区2000年和2002年LandsatTM卫星影像解译数据,对工程建设和运行的生态环境效益予以估算。结果表明:引水工程的建设运行使工程影响区内生态系统的生态环境效益增加了2657 14×104 (约合22054 26×104元人民币),其中水域及耕地生态系统生态效益的增加是研究区生态效益增加的主要方面。     

Some properties of a sequencing batch reactor for treatment of wastewater containing thiocyanate compounds

Thiocyanate (SCN) compounds in photo-processing wastewater (PPWW) could be treated by an SBR system without any release of thiocyanate to the atmosphere during the aeration step. An SCN loading greater than 84 g m(-3)d(-1) showed negative effects on the growth of bio-sludge and removal efficiencies of the system. The acclimatization period of the system was increased with an increase in SCN concentration or loading. The COD, BOD(5), TKN, and SCN removal efficiencies were 96.0 +/- 1.6%, 72 +/- 2%, 49 +/- 5%, and 82 +/- 3%, respectively, under an SCN loading of up to 84 g m(-3)d(-1). The removal efficiency of the system was repressed by SCN due to the repressed growth rate of nitrification bacteria. However, the removal efficiency could be increased with an increase in HRT or a decrease in SCN loading. Also, increases in HRT or decreases in SCN loading led to increased sludge age or solid retention time (SRT) and decreased the sludge volume index (SVI) value. The SRT and SVI of the system with synthetic wastewater containing 840 mg l(-1) SCN under an HRT of 3 days (SCN loading of 280 g m(-3)d(-1)) were 3.9 +/- 0.7 days and 65 +/- 4 ml g(-1), respectively, while they were 11.2+/-0.8 days and 55 +/- 6 ml g(-1), respectively under an HRT of 10 days (SCN loading of 84 g m(-3)d(-1)).