Characteristics of Stabilized Scrubber Sludges

Fly ash, lime, and silica were added to sludge from lime scrubbing process to improve handling and stabilization of sludge for disposal. The addition of fly ash alone does not improve the sludge settling, but does improve sludge filtration. Direct shear tests were made to observe the strength properties of treated sludges as a function of curing time. The lime scrubber sludge was stabilized by adding: (1)Lime and fly ash; or (2)lime, fly ash, and silica. The resulting strength is comparable to that of overconsolidated clays. The pozzolanic reaction and the new gel or crystal formation observed in the stabilized sludges was identified by X-ray diffractometry, scanning electron microscopy, and energy dispersive X-ray analyses. Leachate tests and permeability measurements were performed on raw and stabilized sludges to assess the possible contamination of ground water by toxic elements.