Pore Size Distribution and Hydraulic Conductivity Characteristics of Solidified Sewage Sludge

The hydraulic conductivity of solidified sewage sludge is low because of its high organic matter content, which in turn limits the application of solidified sludge to areas where high hydraulic conductivity is needed. In this study, permeability tests and centrifuge tests were conducted investigate the hydraulic conductivity characteristics of solidified sludge in intact and remolded situations and their relationship to variations in pore size distribution. The results show that solidification changed the sludge morphology from loose flocks to small particles with a diameter of around 50 mu m. In addition, the hydraulic conductivity of intact solidified sludge ranged from 10(-7) to 10(-6)cm/s. After remolding, sludge cured with 40% SAC (sulfoaluminate cement) showed an increase in hydraulic conductivity of two orders of magnitude. The fundamental process governing increases in hydraulic conductivity is the formation of a dual-porosity structure in the remolding process.