title: The viscoelastic behaviour of raw and anaerobic digested sludge: strong similarities with soft-glassy materials.
abstract: Over the last few decades, municipal and industrial wastewater treatment activities have been confronted with a dramatically increasing flow of sewage sludge. To improve treatment efficiency, process and material parameters are needed but engineers are dealing with vast quantities of fundamentally poorly understood and unpredictable material Thus, accurate prediction of critically important, but analytically elusive process parameters is unattainable and is a matter of grave concern. Because engineers need reliable flow properties to simulate the process, this work is an attempt to approach sludge rheological behaviour with well-known materials which have similar characteristics. Sludge liquid-like behaviour is already well documented so, we have focused mainly on the solid-like behaviour of both raw and digested sludge by performing oscillatory measurements in the linear and non-linear regimes. We have shown that the viscoelastic behaviour of sludge presents strong similarities with soft-glassy materials but differences can be observed between raw and digested sludge. Finally, we confirm that colloidal glasses and emulsions may be used to model the rheological behaviour of raw and anaerobic digested sludge.
authors.affiliation: Rheology and Materials Processing Centre, School of Civil, Environmental and Chemical Engineering, RMIT University, Victoria 3001, Australia. jean-christophe.baudez@irstea.fr
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Baudez
authors.forename: Rahul K
authors.initials: RK
authors.lastname: Gupta
authors.forename: Nicky
authors.initials: N
authors.lastname: Eshtiaghi
authors.forename: Paul
authors.initials: P
authors.lastname: Slatter
mesh_terms: D000693:Anaerobiosis; D019563:Mechanics; D012212:Rheology; D012722:Sewage / Q000737:chemistry*; D055682:Viscoelastic Substances; D014865:Waste Disposal, Fluid / Q000379:methods
chemical_list: D012722:Sewage; D055682:Viscoelastic Substances