Structure Evolution of Wastewater Sludge During Electroosmotic Dewatering

An experimental investigation was conducted to explore the characteristics of electroosmotic dewatering of wastewater sludge. Inner pore structure images of sludge were obtained by microcomputed tomography (micro-CT) scanning; the 3D pore structures of sludge and its dynamical evolution were studied by means of pore size distribution (PSD), box-counting fractal dimension, and volume change of sludge matrix. Transport of water content inside sludge was also associated with interactions between local capillary stress and global structural force during electroosmotic dewatering; its impact on the change of pore structure was analyzed. As water content decreased, the local capillary force split the pore surface and created cracks, and the global structural force shrank the sludge matrix and constricted the pore surface. Inner water transport and the evolution of pore structure closely depended on the location between the anode and cathode of electroosmosis.