Dispersion by Chemical Reaction Testing of
Rocky Mountain Arsenal Basin F Waste Soils
JAMES R. PAYNE AND GILES M. MARION
with a natural fatty acid or other material, a hy-
INTRODUCTION
drophobic reagent can be prepared that preferen-
Many military installations have soil contami-
tially adsorbs any organic (or oil/pesticide phase)
nation problems that range from heavy metals to
in a waste liquid or soil/sludge matrix upon ini-
petroleum products. The Rocky Mountain Arse-
tial mixing. Hydrophilic CaO can also be utilized
nal (RMA) near Denver, Colorado, was established
if special rapid-mixing procedures are used to
in 1942 and was the site for the manufacture of
predistribute the waste onto the CaO before hy-
chemical incendiary devices and demilitarization
dration. After this predistribution of the organic
of chemical munitions (Woodward-Clyde 1989).
phase onto the CaO, it undergoes a delayed exo-
An evaporation basin (Basin F) for discharge of
thermic hydration to produce calcium hydroxide
waste effluents was constructed in 1956 and used
[Ca(OH)2] (eq 1), which is fractured into sponge-
until 1981. In 1988, remediation of Basin F began.
like submicron-sized particles that are homo-
Basin F contains high concentrations of salts (high
geneously charged throughout their internal and
ionic strength), heavy metals, ammonia, urea, and
external cavities with the organic phase:
organics, many of which are unidentified (Wood-
CaO + H2O → Ca(OH)2 + energy ↑.
ward-Clyde 1989).
(1)
Initially developed in Germany by Professor
Friedrich Boelsing of the University of Hannover,
Any oils or organics that were previously
the Dispersion by Chemical Reaction (DCR) pro-
adsorbed on the CaO particles are now dispersed
cess has been widely utilized to treat successfully
and bound within the newly formed and highly
more than one million cubic meters of both or-
adsorptive cavities of the hydrophobized Ca(OH)2
ganic and inorganic wastes in Europe for over 18
crystals. The 30- to 40-fold increase in specific
years (Boelsing 1988, 1994; Payne et al. 1992). Most
surface area ensures that no free liquid phase of
recently it has been used in the United States to
the microencapsulated waste remains, and the
stabilize 26,100 tons of sludges from petroleum
resultant product is a free-flowing solid, which
barge-cleaning operations at the NICOR National
can be compacted into a hydrophobized body of
Louisiana Inc. Impoundment Closure in Belle
soil with outstanding soil-mechanical properties.
Chasse, Louisiana, and 233,000 tons of acid tar
When DCR-treated materials are compacted as
residuals remaining from lubricating-oil refining
subgrade for construction (or in a landfill), the
activities at the Sand Springs Superfund Site in
outside surface of the Ca(OH)2 reacts with CO2 to
Sand Springs, Oklahoma. Recently the DCR pro-
cess was used to remediate asphalt tar and other
(eq 2) while still bound in the original soil matrix.
organic-contaminated soils from Eareckson Air
Ca(OH)2 + CO2 → CaCO3 + H2O .
(2)
Force Station at Shemya, Alaska (Brar and Marion
1995; Marion et al., in press). Like several other
By this process, the soil body forms its own self-
stabilization technologies, the patented DCR pro-
healing CaCO3 crust, and the organics are removed
cess utilizes calcium oxide (CaO) as a reagent;
from the biological environment by a combina-
however, by treating normally hydrophilic CaO
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