Influence of thermal effect on vacuum electro-osmosis of Taizhou dredged sediment

Abstract

In recent years, rapid dewatering of dredged sediment has been a key problem in environmental dredging engineering. While vacuum electro-osmosis technology has good application prospects in the treatment of dredged sediment, it has been reported that the thermal effect may improve its efficiency. To further clarify the influence mechanism of the thermal effect of vacuum electro-osmosis, six groups of vacuum electro-osmosis tests under different thermal effects are performed with a homemade test system equipped with a heatable cathode and new electrokinetic geosynthetic (EKG) drainage boards. The obtained results show that the application of a thermal effect at the cathode increases the electro-osmotic flow rate and promotes the drainage process of vacuum electro-osmosis. At the same time, the distribution uniformity of the water content and shear strength after treatment is improved. When the temperature near the cathode is 60 °C, the drainage effect improves. Considering the variation law of the electric permeability coefficient influenced by the thermal effect, the two-dimensional vacuum electro-osmosis consolidation equation is educed. Comparing the observed values with this equation, it is proven that the obtained equation can reasonably reflect the dissipation of excess pore water pressure in vacuum electro-osmosis under the thermal effect.