How to avoid evaporation during rheological measurements of dewatered pasty sludge at high temperature

• Published in: Water science and technology Vol. 79; no. 8; pp. 1503 - 1510
• Main Authors: Mouzaoui, M, Baudez, J C, Sauceau, M, Arlabosse, P
• Format: Journal Article
• Language: English
• Published: England IWA Publishing 01.04.2019
• Subjects: Carbon; Chemical and Process Engineering; Composite materials; Configurations; Desiccation; Driers; Drying; Engineering Sciences; Environmental Engineering; Environmental Sciences; Evaporation; Evaporation control; Evaporation reduction; Fluids mechanics; High temperature; Hot Temperature; Light; Mechanics; Mechanics of materials; Photocatalysis; Residence time; Rheological properties; Rheology; Sewage; Sludge; Temperature; Temperature control; Temperature dependence; Temperature effects; Waste Disposal, Fluid - methods; Water loss; rheology; bad data; pasty sludge; evaporation; high temperature
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2019.150

Controlling the residence time in paddle dryers and the drying efficiency imply the knowledge of rheological behaviour of highly concentrated and pasty sludge and its temperature dependency. However, because of perturbing effects such as evaporation, measurements are not fully representative of intrinsic sludge properties. Classical techniques usually considered in the literature for evaporation control are not efficient at high temperatures. This work gives a method to control the evaporation at high temperature that can be used with any commercial rheometer. The configuration concept is to prevent water loss by limiting the contact between the sheared sludge and the environment. This configuration allows preventing evaporation up to 80 °C at least during 2 h. Its efficiency is confirmed at different total solid (TS) contents ranging from 20 to 47 wt.%.