Energy consumption in a large- scale 3D electro-osmosis-hydraulic synergism system for sludge consolidation

The 3D electro-osmosis-hydraulic synergistic consolidation method is proposed based on the theory of electroosmosis and consolidation to solve the problem of the high energy consumption and large-scale simulation of practice conditions for low permeability and high-water content soils. A set of multi-functional catchment drainage systems combining the synergistic action of the cathode-catchment-intermittent pumping mode is developed. Consolidation of two types of Taihu lake sediments from the Gonghuwan wetland and Baimao Storage site are investigated using this system. Two key indicators of energy consumption per unit volume and displacement per unit volume of the 3D electro-osmosis-hydraulic synergistic consolidation system and the traditional 1D electroosmosis system are analyzed to illustrate the advantage of the 3D system. The results show that the design of water collecting well can greatly reduce the resistance near the soil cathode, intermittently improve the system current, improve the drainage efficiency and reduce the energy consumption. Intermittent pumping can intermittently reduce the system current, and maintain the continuity of system seepage by using the electric and hydraulic synergistic effect. A decrease-increase periodic decrease mode of the current for the 3D electrohydraulic seepage consolidation system is observed. The decrease rate of the current is slower than that of the 1D electro-osmotic system, especially for the soil with high organic matter content, the current in the electroosmotic process is maintained at a relatively higher level, which improves the drainage consolidation efficiency. The energy consumption per unit volume and displacement per unit volume of the 3D electro-hydraulic seepage consolidation system are about 2/3 and 1/30 that of the 1D electro-osmotic system, respectively. The 3D electro-hydraulic seepage consolidation system has remarkable energy saving effect in consolidation and drainage of soft soil with high water content. The 3D electroosmosis-hydraulic consolidation system can greatly improve the drainage consolidation efficiency, greatly reduce energy consumption and better guide the application of the proposed method to the electro-osmotic consolidation of high-water content sludge and another related field.