Table 2. Descriptive chemical charac-
stabilization approaches) achieves its greatest
terization of RMA Basin F liquid*
technological advantage with wastes containing
very high (> 1030%) levels of organics (e.g., die-
(highest historical data).
sel oil residuals and waste oils) because such ma-
Constituent
mg/L
terials facilitate transfer of the contaminants of
Water
620,000
concern onto the hydrophobic CaO reagent be-
fore the dispersion by chemical reaction takes
Major metals
Sodium (Na)
65,000
place. It was apparent that there would not be
Copper (Cu)
5,860
sufficient free organic (oily) phase in the sludge/
Potassium (K)
2,900
soil matrix for optimum DCR processing. It was
Major inorganics
determined in a wettability study that addition of
Chloride (Cl)
159,000
a benign food additive (Archer Daniels Midland
Ammonia (NH3)
60,900
[ADM] regular soy oil soap stock) at 10% of soil
Sulfate (SO4=)
27,000
weight significantly improved the water repel-
Total phosphorus
16,200
Nitrate (NO3)
1,300
lency of the resultant product, so its addition was
implemented as a standard procedure for all fur-
Additional components
ther tests.
Urea
143,000
Dimethylmethylphosphonate
2,000
Following the initial scoping studies completed
in the first week after sample receipt, 0.7-kg scale
* From R.F. Weston Document 1212WG.APA
(12/17/90).
batch preparations were undertaken to generate
sufficient DCR-treated material for independent,
addition to significant levels of pesticides, the
third-party laboratory testing. The initial DCR
Basin F Liquid (later mixed with clean soil to yield
product prepared for outside laboratory analyses
the "soil-amended Basin F sludge") contained
was generated from 55% CaO addition to lime-
very high concentrations of inorganic salts [e.g.,
milk pretreated soil plus 10% ADM soy oil. The
NaCl, NH4Cl, and (NH4)2SO4] as well as 14% urea
total CaO reagent requirement (including that
(Table 2).
used to generate the lime milk slurry) for this
It was determined that the high levels of sulfate
sample was 64.7%. This material and a sample of
(and possibly urea) in the waste (Table 2) were
the raw untreated waste soil were packaged for
interfering with the CaO hydration inherent to the
shipment and transferred under chain of custody
DCR process. As a result, uneconomically high
to the Environmental Lab. The following analy-
levels of CaO reagent were required to obtain an
ses were performed: FID GC (Diesel Range Total
acceptable product. To circumvent this problem,
Petroleum Hydrocarbon Screening, EPA Method
additional tests were undertaken to see if the waste
8015M), ECD GC (EPA Method 8081, Pesticide and
could be pretreated with lime milk [hydrated
PCB Analyses), GC/MS (EPA Method 8270, Total
Ca(OH)2] to tie up the sulfate (for example as gyp-
Waste Analyses), TCLP (EPA Method 1311 Extrac-
sum, CaSO4.2H2O) and also remove the urea.
tion for Pesticides, EPA Method 8081).
These tests were very successful, and it was found
Subsequent to sample shipment, several addi-
that addition of 30% lime milk slurry in H2O
tional larger-scale (1.5 kg) scoping experiments
[Ca(OH)2 at approximately 1013% of contamin-
were completed with SOUND/epic's high inten-
ated soil weight] was sufficient to tie up all the sul-
sity Eirich Mixer. Through these later determina-
fate as gypsum. Then with subsequent addition of
tions, it was found that at the larger batch size
dry CaO for the DCR reaction, it proceeded with-
and with more aggressive mixing, an acceptable
out delay and at economically feasible reagent
product could be obtained with only a 23% CaO
addition levels. The lime milk pretreatment also
addition to lime-milk pretreated soil (total CaO
proved to be an excellent way to remove ammonia
addition, including preparation of lime milk was
by volatilizing any ammonium originally present
27.4%). Because the 27.4% CaO addition is more
as ammonium sulfate and catalyzing the hydroly-
representative of what might be utilized in field
sis of urea to CO2 and ammonia. In field applica-
applications, samples of this DCR-treated mater-
tions, this approach could be used to release and
ial were compacted into a Proctor cylinder for
reclaim ammonia through a specially designed
physical testing. A portion of this compacted cyl-
emissions control capture system on the transport-
inder was allowed to cure and was set aside for
able treatment unit prior to DCR processing.
additional chemical analyses to assess the effects
The DCR process (unlike other pozzolan-based
of lower DCR reagent utilization and sample
6
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