Experimental rheological procedure adapted to dewatered sludge up to 45% dry matter

Abstract : Sludges are characterized by complex rheological properties, strongly dependent on the moisture content and the temperature. This affects in particular the hydrodynamic modelling of dryers where the total solids content (TS) is increasing over the process from around 25% to sometimes up to 90 %. Until now, the literature was mostly focused on the rheological characterization of sludge at low and moderate solids concentration (TS<8-12 %) and a limited attention was paid to pasty and highly concentrated sludge due to the difficulty to carry out the measurements. In consequence, for concentrated sludge, rheological measurements may not be always fully representative of the material properties. This work demonstrates how cracks and fractures can be successfully controlled in classical rotational rheometry in order to obtain intrinsic rheological parameters of highly concentrated sludge. Indeed, a well-controlled experimental procedure is developed to allow the exact determination of the surface really sheared. This surface is calculated during the test by scattering a classical stress sweep with measurements at a reference strain value. The implementation of this procedure shows that pasty and highly concentrated sludges present similarities with granular material (dilatancy or jamming) and that the surface correction is independent of TS in the studied range (14-45 %), resulting in a master curve. In the future, the developed procedure will be implemented to the study of TS effect on the corrected rheological parameters and the evolution of the different regimes observed to fully model the hydrodynamics of dryers.
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Conference papers
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https://hal-mines-albi.archives-ouvertes.fr/hal-01696040
Contributor : Imt Mines Albi Ecole Nationale Supérieure Des Mines d'Albi-Carmaux <>
Submitted on : Tuesday, January 30, 2018 - 8:59:22 AM
Last modification on : Wednesday, October 16, 2019 - 10:40:02 AM

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Mohamed Amine Mouzaoui, J.C. Baudez, Martial Sauceau, Patricia Arlabosse. Experimental rheological procedure adapted to dewatered sludge up to 45% dry matter. SLUDGETECH 2017 - The IWA Specialist Conference on Sludge Management, Jul 2017, London, United Kingdom. 8 p. ⟨hal-01696040⟩

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