Design Framework for Electrokinetically Enhanced Dewatering of Sludge

Abstract

Electrokinetic (EK) dewatering involves the application of a (direct current) voltage across sewage sludge, driving water under an electrical gradient from the positive electrode (anode) to the negative electrode (cathode). Researchers have shown the technique to be efficient means of driving off water from the sludge, thus improving strength and reducing volume. This paper presents an integrating framework for EK dewatering under constant voltage and constant current conditions, founded on the mathematics of simple electrical circuits and demonstrated by laboratory experimentation. The derived equations and experimental results showed that electroosmotic flow rate decreases with time when dewatering with constant voltage and is constant when constant current conditions are maintained. Having a linear relationship between flow and time, EK dewatering with constant current not only enhances the sludge dewatering efficiency, but also has the advantage of simplifying design procedures.