A Rheological Approach for the Evaluation of Geotechnical Use of Water Treatment Sludge

Author(s)

Tsugawa, Juliana K. ; Romano, Roberto C. de O. ; Pileggi, Rafael G. ; Boscov, Maria Eugenia G. ; Zhan, L ; Chen, Y ; Bouazza, A

• Document type: Journal article
• Source: PROCEEDINGS OF THE 8TH INTERNATIONAL CONGRESS ON ENVIRONMENTAL GEOTECHNICS, VOL 1: TOWARDS A SUSTAINABLE GEOENVIRONMENT; v. N/A, p. 9-pg., 2019-01-01.

Abstract

Demand on freshwater tends to increase in the next years; consequently, the production of water treatment sludge (WTS) shall increase as well. Beneficial reuse of WTS as a geotechnical material may be an important strategy to reduce the environmental impacts due to improper WTS disposal. However, even after dewatering WTS consistency is closer to fluids rather than soils. Aiming to the reuse of WTS at considerable amounts, the incorporation of additives to stabilize WTS may be an interesting alternative in the future. For this purpose, the knowledge of rheological characteristics of WTS in fresh state is mandatory. This paper presents a brief about viscoelasticity and rheology concepts, preliminary results of WTS rheological behavior, and two different methods, rotational rheometry and laboratorial miniature Vane test, to evaluate WTS behavior. Rheological tests indicated that Cubatao WTS presents shear thinning behavior at low shear rate, shear thickening at high shear rate, and suggested thixotropic behaviour at low shear rates. Rotational rheometry may be a powerful tool to characterize rheological behavior of WTS, since is very fast method, adapted to pastes and fluids, and can be applied to different conditions of solicitation. Vane test is limited to high water content materials, and higher quantities of sample is needed, but is standardized, and a minimum disturbance of sample occurs. Both methods may be appropriated to characterize WTS and the choosing of the best method depends on the research purpose. (AU)