Landfill Management for Double Alkali Sulfur Dioxide Scrubber Sludge

Based on the results of extensive laboratory tests on two different scrubber sludges from double alkali sulfur dioxide control systems and observations and measurements made at two different field sites, various alternative schemes are presented to dispose of this material in managed landfills. The dry density of loosely placed material ranges from about 25 pcf to 35 pcf (400 kg/m³ to 560 kg/m³), but a small compactive effort usually increases the dry density to 50 pcf or 60 pcf (800 kg/m³ to 960 kg/m³). The addition of fly ash to the scrubber sludge significantly increases its strength and decreases its compressibility, but fixation is not needed to provide sufficient mechanical stability to construct a landfill in much the same manner as followed with a number of soils. Although the coefficient of permeability is on the order of 10⁻⁴ cm/s to 10⁻⁶ cm/s (depending on the dry density), the effect of leachates and associated ground-water contamination can be minimized or virtually eliminated by proper landfill management during and after the disposal operation; impermeable seals may not be required.