Effect of varying water content and applied voltage on the performance of electroosmotic dewatering

¹ Department of Civil, Environmental and Mining Engineering, The University of Western Australia, Perth, WA, 6009, Australia.
² Department of Mechanical Engineering, The University of Western Australia, Perth, WA, 6009, Australia.

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

Electroosmotic (EO) dewatering is a technology that may be employed for the treatment of fine-grained soils with undesirable geotechnical characteristics, such as high compressibility and low undrained shear strengths. Historically, the soil types that have been subjected to EO treatment encompass a broad variety of soils ranging from soft clays with initial water contents close to the liquid limit to low solids content slurries (e.g., dredged sludge and slurry deposited tailings), which typically have a water content far higher than the liquid limit. Despite being a fundamental factor that governs the consolidation behaviour of each soil type, the effect of variation of the pre-treatment water content, to the overall performance of the EO treatment process, has not been quantified. In this study, EO dewatering laboratory-scale experiments were performed considering three consistency levels, corresponding to the water content values of 1, 1.5 and 2 times the liquid limit. The results indicated that the effectiveness of the EO treatment increased with the increase in pre-treatment water content, in terms of proportion of water removed and relative strength gain changes. A major finding of the present study is that the EO dewatering effectiveness significantly increases after the water content of the material increases beyond 1.5 times the liquid limit. Additionally, a new approach to evaluate the energy consumption is presented. The influence of adopted voltage gradient and initial water content on the energy consumption is then evaluated using the results of this study.