Relations entre caractéristiques de la pollution particulaire et paramètres optiques dans les eaux résiduaires urbaines

Abstract : Sampling techniques commonly used for monitoring urban wastewater quality cannot provide a real time or extensive knowledge of the pollution loads conveyed in sewer systems. But needs for continuous monitoring are increasing, and optical measuring methods seem to be suitable for that purpose. Turbidity allows an indirect estimation of the concentration of suspended solids (88) in effluents. But the calibration of turbidity sensors for 88 measurements is not an easy task, and a better knowledge of the relations linking the characteristics of suspended solids and the absorption and scattering of light would be useful. A theoretical approach, based on Mie theory for spherical particles, provides information about some parameters governing absorption of light: nature and size of the particles. But the application to experimental results raised major difficulties to get a proper description of suspended particles. Using the same assumption of spherical particles, two techniques have been compared to analyse the particle size distribution, laser light scattering and sieving. Significant differences have been found, and results could not be interpreted in relation with the model. In addition, the relation between the absorption of light and the concentration of suspended solids appeared very similar for many samples collected from different sites under different circumstances, provided a standardised procedure was applied. A few other samples, all of them coming from one particular combined sewer overflow, did display different calibrating curves. However, these variations could not be linked with measured size distributions. Other factors are still to be investigated, as the density of individual particles, and of their aggregates, as well as the influence of their shape.
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http://docnum.univ-lorraine.fr/prive/INPL_T_2000_MARECHAL_A.pdf
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Submitted on : Thursday, March 29, 2018 - 12:47:39 PM
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Amélie Maréchal. Relations entre caractéristiques de la pollution particulaire et paramètres optiques dans les eaux résiduaires urbaines. Alimentation et Nutrition. Institut National Polytechnique de Lorraine, 2000. Français. ⟨NNT : 2000INPL052N⟩. ⟨tel-01750495⟩

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