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通过多种内河水质净化方法的对比,分析了絮凝沉淀法净化内河水质的优势,阐述了絮凝剂投加和絮凝沉淀设备选用的要点,并以福州市安泰河水质净化工程为例,介绍了絮凝沉淀法净化内河水质的应用效果。 相似文献
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植物滞尘分析及其数学表达模式 总被引:1,自引:0,他引:1
在植被的树冠结构分析、植物滞尘机理和粉尘沉降速度半经验公式的基础上,建立了植物滞留大气颗粒物的数学表达式。利用Beta功能函数φθ(X)、叶面的投影面积、叶面积密度a(z)、叶投影面积分布参数Kx、Kz等描述不同植被冠层的结构特征,并分析了冠层内的空气动力变化和树冠内气溶胶的平衡公式。借鉴Slinn的颗粒物沉降半经验公式、Petroffa等的阔叶滞尘计算模式,植物滞尘沉降通量数学表达式以树冠中树叶的位置为变量、由颗粒物在单片树叶上的各物理机制的沉降速度积分而成。结合国内外植物上沉降速度的试验结果和植物滞尘沉降通量公式的分析结果对影响植物滞尘的主要因素进行了比较分析。 相似文献
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Steven W. Effler David A. Matthews 《Journal of the American Water Resources Association》2004,40(1):251-264
ABSTRACT: The magnitudes and patterns of sediment resuspension are assessed in Cannonsville Reservoir, New York, to quantify and characterize this internal source of sediment. The assessment is based on analyses of sediment trap collections from 10 sites over the spring to fall interval of two years. Temporal and spatial patterns in sediment deposition are demonstrated to be driven by resuspension/redeposition processes. Sediment that had been resuspended and redeposited represented 80 to 96 percent, on average, of the depositing solids collected along the main axis of the lake. About 90 percent of the redeposited sediment was inorganic. Increased resuspension caused by drawdown of the reservoir surface and fall turnover resulted in 10 to 50‐fold increases in deposition rates compared to levels observed when the reservoir was full and strongly thermally stratified. Elevated levels of redeposition from resuspension in the reservoir have been driven by both higher water column concentrations of suspended solids and settling velocities. Recurring longitudinal and lateral gradients in resuspension are delineated, establishing that resuspended solids are transported from the riverine to the lacustrine zone and from near‐shore to pelagic areas. Resuspension is demonstrated to cause increases in inanimate particle (tripton) concentrations. Higher tripton levels have been observed in years with greater drawdown. Water quality impacts of the resuspension phenomenon are considered. 相似文献
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Evaluating the Applicability of a Two‐dimensional Flow Model of a Highly Heterogeneous Domain to Flow and Environmental Management
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Kara J. Carr Tongbi Tu Ali Ercan M. Levent Kavvas 《Journal of the American Water Resources Association》2018,54(1):184-197
Two‐dimensional simulation of highly heterogeneous domains, especially those with disparate length scales, roughness conditions, and geometries, often leads to challenges such as long computation times and numerical instability. Simulation of challenging domains is often needed to guide flood management and environmental regulation agencies in operation and potential domain modifications. This work evaluates the ability of a two‐dimensional unsteady hydrodynamic model to represent long‐duration transient flows over a domain with highly heterogeneous roughness, geometric characteristics, and length scales through bed roughness representation. The domain includes 13 km of Cache Creek and the 14.5 km2 Cache Creek Settling Basin, which traps both sediment and mercury. Calibration under different bed roughness methods, validation, and modeling results of bathymetric modification scenarios are presented. The modeling approach's performance supports its application as a tool for management of similar domains, such as settling basins, leveed floodplains, and reservoirs. Accurate representation of flow dynamics can also inform environmental management that involves transport of sediments, nutrients, and heavy metals. This study found that a two‐dimensional unsteady flow model can accurately represent long‐duration transient flow in a large settling basin with highly heterogeneous characteristics without parsing of the domain or flow events simulated. 相似文献
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颤蚓污泥减容效果及其影响因素分析 总被引:6,自引:0,他引:6
通过批沉降实验考察了颤蚓对一系列来源不同、性质不同的活性污泥沉降性能的影响.结果表明,颤蚓污泥减容效果显著.对活性污泥的主要性质指标进行Pearson偏相关分析后.发现污泥本身的污泥沉降比(SV,亦称30min沉降率)和半沉降时间t50是影响颤蚓污泥减容作用的重要因素,而并非污泥浓度TSS和SVI.其中,SV分别与颤蚓作用60min后的污泥减容率η(SV60)及污泥半沉降时间的减少率η(t50)之间显著相关.另外,在污泥性质相同的情况下,颤蚓污泥容积比也是影响颤蚓污泥减容效果的重要因素,单位容积下颤蚓投加量越大,污泥减容率会越高. 相似文献
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