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Título del libro: World Water Congress 2005: Impacts Of Global Climate Change - Proceedings Of The 2005 World Water And Environmental Resources Congress
Título del capítulo: Probabilistic approach to residence-time distribution in water treatment units

Autores UNAM:
ALEJANDRA MARTIN DOMINGUEZ;
Autores externos:

Idioma:

Año de publicación:
2005
Palabras clave:

Hydraulic behavior; Residence time distribution function; Stirred tank reactors; Treatment efficiency; Hydraulics; Laplace transforms; Probability distributions; Water treatment


Resumen:

Imperfect hydraulic behavior of water treatment units, expressed by stagnation zones and bypassing, may substantially reduce the treatment efficiency. Flow tracing residence-time distribution based techniques are commonly used to identify if such undesirable effects take place inside the unit and what is their extent. A probabilistic approach to obtain the theoretical residence-time distribution function for a series of continuously stirred tank reactors with possible stagnation zones and bypassing is presented in. this paper. It is shown that binomial probability distribution can be used to describe the passage of a particle through the series of N reactors with possible bypassing at each individual reactor. The well known residence-time distribution functions for one or several continuously stirred tank reactors with no stagnation zones and no bypassing, are also shown to be obtained in terms of probability. Applying these principles, the residence-time distribution function is derived providing some physical insight. The result is identical to that obtained earlier by Laplace transform technique. An optimization procedure, implemented in MSExcel, is then used to obtain the number of tanks, and the fraction of stagnation zones and bypassing minimizing the difference between tracer test data and unit's residence-time distribution function. Results were compared with experimental data obtained from actual drinking-water treatment plants in Mexico. © copyright ASCE 2005.


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