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221.
Robert J. Davies-Colley David G. Smith 《Journal of the American Water Resources Association》1992,28(5):951-957
ABSTRACT: The black disk method for measuring visual water clarity in situ is becoming established as a simple but robust method for optically characterizing natural waters. However, in spite of its virtues, the method is limited by a practical visibility minimum of around 0.1 m and the requirement for direct access to the water body at a point where there is adequate lighting for the visual observations. A method has been devised for measuring black disk clarity off-site on samples of waters, diluted if necessary, and contained in a trough constructed of galvanized steel. In 23 streams, rivers, and lakes of diverse optical and physical character, measurements of visual clarity of water samples contained in troughs agreed closely with in situ measurements and correlated well (inversely) with the beam attenuation coefficient measured by transmissometer. Therefore, at sites where in situ measurement is difficult, visual clarity of waters can be measured offsite on a water sample. Furthermore, the visibility of samples diluted with tap water of known clarity was predictable from a simple balance on light attenuation. This means that useful visual clarity measurements on very turbid waters and effluents can be made in a trough containing volumetrically diluted samples, so extending application of the black disk method to very low visual ranges. 相似文献
222.
This article aims to describe the influence of di use pollution on the temporal and spatial characteristics of natural organic matter
(NOM) in a stratified dam reservoir, the Daecheong Dam, on the basis of intensive observation results and the dynamic water quality
simulation using CE-QUAL-W2. Turbidity is regarded as a comprehensive representation of allochothonous organic matter from di use
sources in storm season because the turbidity concentration showed reasonable significance in a statistical correlation with the UV
absorbance at 254 nm and total phosphorus. CE-QUAL-W2 simulation results showed good consistency with the observed data in terms
of dissolved organic matter (DOM) including refractory dissolved organic carbon (RDOC) and labile DOC and also well explained the
internal movement of constituents and stratification phenomenon in the reservoir. Instead turbidity and NOM were related well in the
upper region of the reservoir according to flow distance, gradually as changing to dissolved form of organic matter, RDOM a ected
organic matter concentration of reservoir water quality compared to turbidity. To control the increase of soluble organic matters in the
dam reservoir, appropriate dam water discharge gate operation provided e ective measurement. Because of the gate operation let avoid
the accumulation of organic matter within a dam reservoir by shorten of turbid regime retention time. 相似文献
223.
通过对污水处理厂二沉池出水的后置化学除磷试验研究,分析了药剂种类、二沉池出水磷浓度和浊度对化学除磷效果的影响。实验结果表明,聚合硫酸铁的化学除磷效果略优于聚合氯化铝。随着进水磷浓度的升高,投加Fe/去除P的摩尔比会明显降低,这可能与化学除磷沉淀物的吸附和络合作用有关。二沉池出水浊度对后置化学除磷具有竞争性影响,较高的出水浊度将增大药剂消耗量。因此,污水处理厂采用化学加药后除磷工艺时,应根据二沉池出水总磷和浊度范围进行最佳投药量试验,并采取自动控制措施根据出水水质调节加药量,确保出水总磷稳定达标。 相似文献
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沼液中悬浮物对乙醇发酵的影响及其絮凝处理的研究 总被引:1,自引:0,他引:1
乙醇-沼气双发酵耦联工艺的应用有望实现乙醇工业工艺废水"零排放"的目标.本研究对该耦联工艺的回用配料水——中温沼液中的悬浮物对乙醇发酵的影响进行了考察,并对其去除方法进行了确定.结果表明,沼液中悬浮物的存在会促进酵母细胞的繁殖,提高发酵速率,但副产物甘油及小分子有机酸的量大幅上升,而主产物乙醇的生成量减少,悬浮物对乙醇合成的临界抑制浓度为0.35 g·L-1(干重).采用不同的絮凝剂及絮凝方式对沼液中的悬浮物进行去除,发现絮凝剂聚合氯化铝(PAC,300 mg·L-1)与阳离子聚丙烯酰胺(CPAM,2 mg·L-1)协同处理时效果最佳,对沼液浊度、色度的去除率分别为92.4%、23.7%,所得上清液的悬浮物粒径小于2μm,PAC、CPAM的残留量分别为0.82、0.03mg·L-1.絮凝处理后消除了悬浮物对乙醇合成的抑制作用,且絮凝处理后沼液回用的发酵性能略优于离心所得沼液回用的发酵水平,达到了预期的目的. 相似文献
227.
Carl F. Cerco Mark R. Noel Ping Wang 《Journal of the American Water Resources Association》2013,49(5):1091-1102
The shallow‐water component of the Chesapeake Bay Environmental Model Package emphasizes the regions of the system inside the 2‐m depth contour. The model of these regions is unified with the system‐wide model but places emphasis on locally significant components and processes, notably submerged aquatic vegetation (SAV), sediment resuspension, and their interaction with light attenuation (Ke). The SAV model is found to be most suited for computing the equilibrium distribution of perennial species. Addition of plant structure and propagation are recommended to improve representation of observed trends in SAV area. Two approaches are taken to examining shallow‐water Ke. The first compares observed and computed differences between deep‐ and shallow‐water Ke. No consistent difference in observations is noted. In the preponderance of regions examined, computed shallow‐water Ke exceeds computed deep‐water Ke. The second approach directly compares Ke measured in shallow water with modeled results. Model values are primarily lower than observed, in contrast to results in deep water where model values exceed observed. The shortfall in computed Ke mirrors a similar shortfall in computed suspended solids. Improved model representation of Ke requires process‐based investigations into suspended solids dynamics as well as increased model resolution in shallow‐water regions. 相似文献
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