Consolidation of High Ash Papermill Sludges

Experimental laboratory results for one-dimensional compression behavior of dewatered pulp and papermill sludges are presented. Data were obtained with a fixed-ring oedometer and a pressurized consolidation cell on a secondary fiber mill sludge in the natural state, at different organic contents, and with lime or flyash admixtures. Conclusions include: compression index remained constant for load increment ratios of 1.0 to 0.25, showed a linear decrease with increase in initial solids content by weight, and had a linear relationship with organic content for comparisons at the same solids content by volume; for small load increments measured pore pressures dissipated more rapidly than predicted by theory; the rate of secondary compression per unit pressure increased with decrease in load increment ratio; lime or flyash admixtures increased the coefficient of consolidation; temperature increase reduced the equilibrium void ratio, altered the coefficient of consolidation, and increased secondary compression rates.