منابع مشابه
Can Earthworms De-Clog Sand Filters?
Two species of earthworms, Lumbricus terrestris and Eisenia fetida, were used to de-clog sand filters purifying domestic sewage. The experimental set-up consisted of 6 filtration columns (4 research filters and 2 control filters) filled with fine sand (d60=0.2 mm, d10=0.1 mm). The sewage parameters at inflow to the filters were typical of the septic tank effluent. The filters were fed about 5.5...
متن کاملEffects of dynamic operating conditions on nitrification in biological rapid sand filters for drinking water treatment.
Biological rapid sand filters are often used to remove ammonium from groundwater for drinking water supply. They often operate under dynamic substrate and hydraulic loading conditions, which can lead to increased levels of ammonium and nitrite in the effluent. To determine the maximum nitrification rates and safe operating windows of rapid sand filters, a pilot scale rapid sand filter was used ...
متن کاملOn the size distribution of sand
A model is presented of the development of the size distribution of sand while it is transported from a source to a deposit. The model provides a possible explanation of the log-hyperbolic shape that is frequently found in unimodal grain size distributions in natural sand deposits, as pointed out by Bagnold. It implies that the size distribution of a sand deposit is a logarithmic normal-inverse...
متن کاملGranular size segregation in underwater sand ripples.
We report an experimental study of a binary sand bed under an oscillating water flow. The formation and evolution of ripples is observed. The appearance of a granular segregation is shown to strongly depend on the sand bed preparation. The initial wavelength of the mixture is measured. In the final steady state, a segregation in volume is observed instead of a segregation at the surface as repo...
متن کاملIntegration of CAD and rapid manufacturing for sand casting optimisation
In order to reduce the time and the costs of the products development in the sand casting process, the SMC Colombier Fontaine company has carried out a study based on a tooling manufacturing with a new rapid prototyping process. This evolution allowed the adequacy of the geometry used for the simulation to the tooling employed physically in the production. This allowed a reduction of the wall t...
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ژورنال
عنوان ژورنال: American Journal of Public Health
سال: 1922
ISSN: 0271-4353
DOI: 10.2105/ajph.12.1.44