Case Studies: Full-Scale Operations and Delivery Systems - Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes - page 355

was suitable for local, sanitary landfill as a non-toxic solid. The waste contained
high levels of dissolved organics and salts as well as dissolved antimony.

13.4.3.2 Treatability Studies

The waste was a low-viscosity, semi-clear solution with very little suspended solids.
The dissolved antimony (234 ppm) was the main hazard. While there were no
applicable federal standards at that time for metal leachability, or even a standard
leaching test, the state of Louisiana was willing to allow disposal of this waste in a
local landfill if it was converted into a stable, workable solid with reduced antimony
leachability. Table 13.7 gives the results of the waste analysis before treatment. The
S/S process used a combination of portland cement and sodium silicate solution to
quickly set and then harden the liquid waste. Prior to the addition of S/S reagents,
the waste was pretreated with hydrated lime to precipitate, or expel from aqueous
solution, some of the dissolved organics. This aided in solidifying the waste by
reducing the dissolved organic interference to cement setting, and by providing more
suspended solids, and thereby reduced the requirements for the S/S reagents.
After S/S treatment and curing, the solid was tested for strength using a
penetrometer and was leached in a vendor-developed column-leaching test. This
test required crushing the solid into pieces about 3 / 8 in. in maximum size, placing
the crushed solid in a glass column approximately 2 in. in diameter, and allowing
deionized water to pass through the material slowly and in such a way as to assure
complete contact between the waste and the leachant. The test was continued until
the equivalent of 100 in. of simulated rainfall had permeated the waste, usually a
time of several days or more. The permeate was then analyzed for leached con-
stituents. This test was similar to other experimental procedures used at the time
until EPA mandated the Extraction Procedure Toxicity Test (EPT) and later the
TCLP.

TABLE 13.7
Analysis of the Raw Waste -
Case Study #3

Concentration
(wt%) Contaminant

Ethylene glycol 6.6

Diethylene glycol 0.2

Sodium terephthalate 2.5

Sodium chloride 8.3

Sodium sulfate 0.9

Ammonium chloride 1.1

Antimony 0.0234