Characteristics of stabilized scrubber sludges

Flyash, lime, and silica were added to sludge from a lime scrubbing process to improve handling and stabilization of the sludge for disposal. Addition of flyash did not improve the initial settling velocity of the sludge. Total filter yields and true filter yields were improved partly by addition of flyash. Lime scrubber sludge was stabilized by adding: lime and flyash; or lime, flyash, and silica. The resulting strength is similar to that of overconsolidated clays. New gel or crystal formation was observed in stabilized sludges, and could be responsible for the gain in sludge strength. Fixation of sludge reduced permeability and retarded the mobility of arsenic, boron, calcium, chloride, and other compounds. Lattice complexes formed may help to prevent leaching of these substances. Fixation did not significantly retard mobility of aluminum, cadmium, COD, chromium, copper, lead, phosphate, and other elements. (9 graphs, 3 photos, 17 references, 6 tables)