title: Rheological characterization of digested sludge by solid sphere impact.
abstract: An impact method was applied to investigate the rheological characteristics of digested sludge and reveal its transient dynamics. A high-speed camera allowed visualizing the dynamic impact process and observing interaction between impacting sphere and targeted sludge. A damping oscillation was observed after the impact. The crater diameter followed an exponential function, while the crater depth varied as a logarithmic function of both sphere diameter and free fall height. Furthermore, the viscosity and elasticity of digested sludge were evaluated by establishing a simplified impact drag force model. The impact elastic modulus was consistent with the Young's modulus measured by a penetrometer. The impact viscosity was reasonable as the estimated impact shear stress was greater than the yield stress of digested sludge resulting in the formation of crater. The impact method offers an alternative way to reveal the viscoelasticity of digested sludge through a dynamic process.
authors.affiliation: Laboratory of Reactions and Process Engineering, University of Lorraine, CNRS, 1, rue Grandville, BP 20451, 54001 Nancy Cedex, France; CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei 230026, China.
authors.forename: Jiankai
authors.initials: J
authors.lastname: Jiang
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wu
authors.affiliation: Laboratory of Reactions and Process Engineering, University of Lorraine, CNRS, 1, rue Grandville, BP 20451, 54001 Nancy Cedex, France.
authors.forename: Souhila
authors.initials: S
authors.lastname: Poncin
authors.affiliation: Laboratory of Reactions and Process Engineering, University of Lorraine, CNRS, 1, rue Grandville, BP 20451, 54001 Nancy Cedex, France. Electronic address: Huai-Zhi.Li@univ-lorraine.fr.
authors.forename: Huai Z
authors.initials: HZ
authors.lastname: Li
mesh_terms: D055119:Elastic Modulus; D008962:Models, Theoretical; D012212:Rheology / Q000379:methods*; D012722:Sewage / Q000737:chemistry*; D013314:Stress, Mechanical; D014783:Viscosity
chemical_list: D012722:Sewage
keywords: Crater; Digested sludge; High-speed camera; Impact method; Rheological characterization