EPA/600/R-02/019
September 2001
Stabilization and Testing of Mercury
Containing Wastes: Borden Catalyst
by
Linda A. Rieser, Paul Bishop, Makram T. Suidan,
Haishan Piao, Renee A. Fauche, and Jian Zhang
Department of Civil and Environmental Engineering
University of Cincinnati
Cincinnati, Ohio 45221-0071
Contract No. 68-C7-0057
Task Order #20
Task Order Manager
Paul Randall
Land Remediation and Pollution Control Division
National Risk Management Research Laboratory
Cincinnati, Ohio 45268
National Risk Management Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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Notice
The U.S. Environmental Protection Agency, through its Office of Research and Development, funded
and managed the research described here under contract number 68-C7-0057, Task Order #20 to the
University of Cincinnati. It has been subjected to the U.S. EPA' s peer and administrative review and has
been approved for publication as an EPA document. Mention of trade names or commercial products does
not constitute an endorsement or recommendation for use.
11
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Foreword
The U.S. Environmental Protection Agency is charged by Congress with protecting the Nation' s land, air,
and water resources. Under a mandate of national environmental laws, the Agency strives to formulate
and implement actions leading to a compatible balance between human activities and the ability of natural
systems to support and nurture life. To meet this mandate, EPA' s research program is providing data and
technical support for solving environmental problems today and building a science knowledge base
necessary to manage our ecological resources wisely, understand how pollutants affect our health, and
prevent or reduce environmental risks in the future.
The National Risk Management Research Laboratory is the Agency' s center for investigation of
technological and management approaches for preventing and reducing risks from pollution that threatens
human health and the environment. The focus of the Laboratory's research program is on methods and
their cost-effectiveness for prevention and control of pollution to air, land, water, and subsurface
resources; protection of water quality in public water systems; remediation of contaminated sites,
sediments and ground water; prevention and control ofindoorairpollution; and restoration of ecosystems.
NRMRL collaborates with both public and private sector partners to foster technologies that reduce the
cost of compliance and to anticipate emerging problems. NRMRL's research provides solutions to
environmental problems by: developing and promoting technologies that protect and improve the
enviro nment; advancing scientific and engineering information to support regulatory and policy decisions;
and providing the technical support and information transfer to ensure implementation of environmental
regulations and strategies at the national, state, and community levels.
This publication has been produced as part of the Laboratory's strategic long-term research plan. It is
published and made available by EPA' s Office of Re search and Development to assist the user community
and to link researchers with their clients.
E. Timothy Oppelt, Director
National Risk Management Research Laboratory
111
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Abstract
This report was submitted by the University of Cincinnati (UC) in fulfillment of Contract No. 68-C7-
0057 under the sponsorship of the U.S. Environmental Protection Agency (EPA). This report covers a
period from June 1999 through July 2000; laboratory work was completed as of July 2000. This report
evaluates the chemical stability of spent mercuric chloride catalyst in an aqueous environment before and
after treatment with stabilizing agents. The stabilizing agents evaluated in this study are sulfide and
phosphate.
Samples obtained by UC and EPA personnel at the Borden Chemicals and Plastics (BCP) plant on June
10, 1999 were characterized for total mercury content, pH, and acidity prior to performing the leaching
tests on untreated waste. Leaching tests and analytical work performed by UC and their contract
laboratories included the toxicity characteristic leaching procedure (TCLP), solid stability in water, and
leaching at constant and variable pH values.
After completing the baseline tests on untreated waste, the spent mercuric chloride catalyst was treated
with sulfide and phosphate binders to evaluate the effectiveness of these additives on reducing the
concentration of mercury in the leachate. The mercuric chloride waste was crushed and combined with
the binders at various molar ratios and pH ranges prior to performing the identical leaching tests noted
above.
Measured mercury concentrations in the generated leachates indicate that sulfide treatment lowers the
aqueous mercury concentration, while phosphate treatment has little effect on decreasing the mercury
concentration. Analytical results for individual leaching methods carried out over apH range of 2 to 12
do not define a consistent trend for mercury concentrations as a function of pH. However, samples treated
with moderate to large amounts of sulfide (i.e., a S/Hg molar ratio greater than 3) released less mercury.
IV
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Table of Contents
Foreword iii
Abstract iv
1.0 Background 1
1.1 Waste Characterization 1
1.2 Leaching Tests 1
1.3 Treatment Reagents 1
2.0 Characterization of BCP Catalyst 2
3.0 Leaching Tests 2
3.1 Solid Stability in Water for Untreated Catalyst 2
3.1.1 Introduction 2
3.1.2 Procedure 3
3.1.3 Results 3
3.1.4 Data Quality Discussion 4
3.2 Acidity of Untreated Catalyst 4
3.2.1 Introduction 4
3.2.2 Procedure 5
3.2.3 Results 5
3.2.4 Data Quality Discussion 6
3.3 Toxicity Characteristic Leaching Procedure 6
3.3.1 Introduction 6
3.3.2 Procedure 6
3.3.3 Results 7
3.3.4 Data Quality Discussion 7
3.4 UC Constant pH Leaching Test 8
3.4.1 Introduction 8
3.4.2 Procedure 8
3.4.3 Results 8
3.5 RU-SR002.1 (Solubility and Release as a Function of pH) 9
3.5.1 Introduction 9
3.5.2 Procedure 9
3.5.3 Results 10
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Table of Contents, Continued
4.0 Stabilization Treatments 11
4.1 Stabilization of BCP Catalyst by Sulfide 11
4.1.1 Introduction 11
4.1.2 Procedure 11
4.1.3 Results 12
4.1.4 Discussion 18
4.2 Stabilization of BCP Catalyst by Phosphate 19
4.2.1 Introduction 19
4.2.2 Procedure 20
4.2.3 Results 20
4.2.4 Discussion 23
5.0 Data Quality 24D
5.1 Background Characterization 24D
5.2 Leaching Tests 24D
5.3 Acidity 27D
5.4 Treatment Reagents 27D
6.0 Conclusions 33D
Appendices
Al Analytical Data - Environmental Enterprises Inc. - Provided upon request, Paul Randall, USEPA,
Cincinnati, OH, 513 569-7673 or email Randall.Paul@epa.gov
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List of Tables
2.1 Chemical Characterization of Untreated BCP Catalyst 2
3.1 Solid Stability in Water for Untreated Spent Catalyst 4
3.2 Acidity Results 5
3.3 TCLP Resultsfor Untreated Catalyst 7
3.4 Constant pH Leaching Results for Untreated Catalyst 9
3.5 RU-SR002.1 Leaching Results for Untreated Catalyst 10
4.1 Sample Test Matrix 12
4.2 Mercury Results for Sulfide Stabilization 13
4.3 Stabilization Efficiency (%) 15
4.4 TCLP Mercury Results (mg/L) for Sulfide Stabilization 16
4.5 Stabilization Efficiency for TCLP Data 17
4.6 Mercury Results for Phosphate Stabilization 21
4.7 TCLP Mercury Results (mg/L) for Phosphate Stabilization 23
5.1 Laboratory QC Data for EEI Total & TCLP Mercury Results 25
Background Data
5.2 Laboratory QC Data for EEI Total Mercury Results 26
Solid Stability in Water
5.3 Laboratory QC Data for EEI Total Mercury Results 26
University of Cincinnati pH Test
5.4 Laboratory QC Data for EEI Total Mercury Results 27
Rutgers University pH Test
5.5 Laboratory QC Data for EEI Total Mercury Results 29
Sulfide and Phosphate Stabilization
5.6 Laboratory QC Data for EEI TCLP Mercury Results 31
Sulfide and Phosphate Stabilization
5.7 Experimental QC Data for Test Duplicates 32
Sulfide and Phosphate Stabilization
Vll
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List of Figures
3.1 Acidity of Untreated Catalyst vs. Sample Solid 6
4.1 Mercury Results for Sulfide Stabilization as a Function of pH 14
4.2 Stabilization Efficiency(%) 15
4.3 TCLP Mercury Results for Sulfide Stabilization 16
4.4 Stabilization Efficiency for TCLP Data 17
4.5 Distribution of the Various Hg-H-S Species as a Function of pH 19
4.6 Mercury Results for Phosphate Stabilization 21
4.7 TCLP Mercury (mg/L) Results for Phosphate Stabilization 22
Vlll
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1.0 Background
The Borden Chemicals and Plastics plant (BCP) in Geismar, Louisiana
produces, among other chemicals, vinyl chloride. The vinyl chloride synthesis
employs a mercuric chloride catalyst, which is the subject of this study.
LI Waste Characterization
Spent mercuric chloride catalyst samples collected at the BCP plant
werecharacterized for total mercury content, pH and acidity by UC and a contract
laboratory prior to initiating the leaching tests. A summary of this information is
provided in Section 2.0.
1.2 Leaching Tests
A variety of leaching tests were carried out with the untreated and treated
mercuric chloride waste to evaluate the physiochemical controls on mercury mobility
(e.g., dissolution, diffusion and/or solubility). The liquid/solid mass ratio was varied
from 20 to 200 to investigate diffusion gradients, TCLP tests were used to evaluate
the suitability of disposing of untreated and treated waste in landfills, and constant and
variable pH tests were used to examine the leaching behavior of mercury over the pH
range of 2 to 12. Section 3.0 presents the procedures and results for all test sequences.
1.3 Treatment Reagents
Treatment reagents applied to the spent catalyst consisted of sodium sulfide
and sodium phosphate. The treated waste forms were prepared at various molar ratios
(e.g., S/Hg = 1, 3, 5 and 7) and then leached at pH values that were initially set at 2,
4, 6, 8 and 10. Results are provided in Section 4.0.
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2.0 Characterization of BCP Catalyst
On June 10, 1999 UC and EPA personnel collected samples of spent
mercuric chloride catalyst from 5 5-gallon drums staged at the Geismar,
Louisiana BCP plant. Approximately 10 kilograms (kg) of waste was
collected and homogenized prior to performing the baseline characterization.
The waste was homogenized by tumbling in a five gallon container for 24
hours before sampling. Observations of the homogenized waste detected no
visual heterogeneity. The samples were analyzed for total mercury, pH and
acidity (Table 2.1) to establish baseline conditions for the waste prior to
initiating the leaching tests. Laboratory QC data associated with the reported
mercury results are presented and discussed in Section 5.1.
Table 2.1 Chemical Characterization of Untreated BCP Catalyst
Chemical Parameter
Total Mercury
(2 grab samples)
pH
Acidity
Concentration
20,800 mg/kg
22,300 mg/kg
2.10
0.54mgCaCO3/g
Method of Analysis
SW-846-747QA1
SW-846-7470A1
pH electrode2
Standard Methods
(1) Analysis performed by Environmental Enterprises Incorporated, Cincinnati, Ohio
(2) Analysis performed by University of Cincinnati, Cincinnati, Ohio
3.0 Leaching Tests
3.1 Solid Stability in Water for Untreated Catalyst
3.1.1 Introduction
This test varies the liquid/solid mass ratio to study the effect of the
aqueous contaminant concentration on the diffusion of contaminants from
the waste form. If the amount of contaminant released from the waste form
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decreases as the liquid-solid ratio decreases, then the contaminant
concentration in the leachate may be great enough to reduce the
concentration gradient between the leachate and the waste form and impede
its diffusion from the waste.
3.1.2 Procedure
Samples of spent mercuric chloride catalyst were dried at room
temperature for 24 hours in an exhaust hood.(1) Four tests were run using
10, 20, 50 and 100 grams of waste. Each solid sample was placed in a 2-
liter Nalgene HDPE bottle and then filled with 2 liters of deionized water.
The bottles were capped and tumbled for 18 hours and then each leachate
sample was filtered through a 0.45 |j,m filter and placed in a sample
container. Each leachate sample was acidified to a pH of less than 2 with
HNO3 and stored at 4°C until analyzed within the 28 day holding-time
requirement. Mercury concentrations were measured by cold vapor atomic
absorption spectroscopy (CVAAS).
3.1.3 Results
As shown in Table 3.1, the aqueous mercury concentration
increased and the percent of total mercury leached from the waste
decreased as the liquid/solid mass ratio decreased (i.e., the mass of solid
increased). In terms of total mercury leached from the waste, Sample 1
released over 4 times more mercury than Sample 4. This observation,
along with the higher aqueous concentration seen in Sample 4, suggests that
a reduction in the concentration gradient between the leachate and waste
may impede the diffusion of mercury from the waste form. Alternatively,
the similarity in aqueous concentration for Samples 3 and 4 may indicate a
This represents a change from the QAPP oven drying method. Assuming that moisture
could still be present in the catalyst, values obtained could be conservative as compared to
the oven dry, dry weight basis. Moisture content analysis, however, showed no moisture
present in the catalyst.
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solubility limit is controlling the amount of mercury released from the
waste.
Table 3.1 Solid Stability in Water for Untreated Spent Catalyst1
Liquid / Solid Mass Ratio
Spent Catalyst (g/L) / Mercury (mg)
Mercury in Leachate (mg/L)
Total Mercury Leached (%)
Sample
1
200:1
5/108
2.88
2.7
Sample
2
100:1
10/216
4.34
2.0
Sample
3
40:1
25/539
6.30
1.2
Sample
4
20:1
50/108
6.76
0.6
(1) Mercury Analysis performed by Environmental Enterprises Incorporated, Cincinnati, Ohio
3.1.4 Data Quality Discussion
The solid stability-in-water test provides only single point estimates.
As leachates were measured at a single time point (18 hours), there is no
information on whether the interval was sufficient to establish mercuric
equilibrium between the solid and solution phases. Section 5.2 provides the
data quality analysis for Solid Stability in Water Results.
3.2 Acidity of Untreated Catalyst
3.2.1 Introduction
Acidity is related to the capacity of a material to react with a strong
base. An acidity titration was run on each leachate produced from the solid
stability tests to assess the acidic content of the spent catalyst. Each sample
was titrated with a strong base to an end point pH of 9 to obtain a smooth
titration curve. Construction of the titration curve identifies the inflection
points and determines the buffering capacity of the leachate.
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3.2.2 Procedure
A known volume of leachate (40 mL) from the solid-stability-in-water
test was placed in a breaker and a 0.1N sodium hydroxide titrant was added
to the sample in incremental amounts until the end point was obtained. The
amount of sodium hydroxide required to neutralize the acidity of the sample
is expressed as equivalent milligrams (mg) of CaCO3 relative to a liter (L) of
leachate and normalized to a gram (g) of the spent catalyst. An Orion
electrode was used to measure the pH of the leachate.
3.2.3 Results
The resulting acidity for each sample is shown in Table 3.2, and Figure
3.1 shows measured acidity in the leachate versus mass of spent catalyst. The
plot is linear, indicating that acidity is dependent on the amount of spent
catalyst available for leaching.
Table 3.2 Acidity Results1
Liquid/Solid Ratio (w/w)
Spent Catalyst (g/L)
Acidity (as mg CaCO3/L)
Normalized acidity(mg CaCO3/g)
20:1
50
51.25
1.03
40:1
25
22.50
0.90
100:1
10
8.75
0.88
200:1
5
7.50
1.50
(1) Analysis performed by University of Cincinnati, Cincinnati, Ohio
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60
a =o.5n
50 -I R'= 0.9874
^ 40 -
O
(TS
I3M
••^s
^
^S 20 J
10 -
20 40 60 80 100 120
Sample(g)
Figure 3.1: Acidity of Untreated Catalyst vs Sanple Solid
3.2.4 Data Quality Discussion
Data generated in acidity analyses consist of single point estimates.
Section 4.5.6 provides the data quality analysis for the Acidity data.
3.3 Toxicity Characteristic Leaching Procedure (TCLP)
3,3,1 Introduction
This test is used to determine the potential mobility of contaminants
in an acetic acid solution that is intended to serve as simulated leachate under
landfill conditions.
3.3.2 Procedure
Prior to performing the TCLP analysis, an initial pH measurement of
the waste must be made to determine the appropriate pH of the extraction
fluid (4.93 or 2.88) that must be used in the test. The pH of the untreated BCP
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spent catalyst is 2.10. This pH value is well below pH 5, thus the TCLP
method dictates that the extraction fluid corresponding to a pH of 4.93 must
be used.
A total of 100 grams of dried spent catalyst were added to a 2-liter
container with 2 liters of extraction fluid to yield essentially no head space in
the container. The containers were sealed and then rotated end-over-end for
18 hours. Each leachate sample was then filtered through a 0.70 |j,m filter and
placed in a sample container. The leachate samples were acidified to a pH of
less than 2 with HNO3 and stored at 4°C until analyzed within the 28 day
holding-time requirement. Mercury concentrations were measured by
CVAAS.
3.3.3 Results
Table 3.3 summarizes the analytical results for the TCLP test and
indicates that both samples of untreated catalyst had mercury leachate
concentrations orders of magnitude above the TCLP limit of 0.2 mg/L.
Table 3.3 TCLP Results for Untreated Catalyst1
Sample
TCLP (mg/L)
Total Mercury (mg/kg)
Limit
0.2
1
123
20,800
2
120
22,300
(1) Mercury analysis performed by Environmental Enterprises Incorporated, Cincinnati, Ohio
3.3.4 Data Quality Discussion
The relative percent difference for the TCLP duplicate is 2.47%.
Laboratory QC data associated with the reported mercury results are
presented and discussed in Section 5.1.
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3.4 UC Constant pH Leaching Test
3.4.1 Introduction
Constant pH leaching tests are a means to determine the effect pH has
on mobilizing contaminants found in waste samples. The basic premise of this
test is to leach samples in a constant pH solution, adjusting the sample pH to
the set point as necessary.
3.4.2 Procedure
The leaching tests were run at pH values of 2, 4, 6, 8, 10 and 12 using
500 mL of deionized water and 25 grams of dried solid to produce a
liquid/solid mass ratio of 20:1. A duplicate test was run at a pH value of 8.
The samples were stirred using stirring bars on stir plates throughout the
experiment. The pH was maintained at the initial value for a 24 hour period,
with samples being extracted for analysis at 2, 10 and 24 hours. The samples
were filtered through a 0.7 jam glassfiber filter, acidified to a pH of less than
2 with HNO3 and stored at 4°C until analyzed within the 28 day holding-time
requirement. All samples were analyzed via CVAAS.
3.4.3 Results
Table 3.4 summarizes the reported mercury concentrations for each
distinct pH test carried out. At a pH of 2, a steady-state condition may have
been reached between 10 and 24 hours, as the mercury concentrations for
these time intervals are within 10 percent of each other. For other pH values,
it is hard to tell if a steady-state condition was reached because mercury
concentrations continued to increase through the entire time interval. A longer
testing period is recommended for future research. In any event, the mercury
concentrations are highest at the low and high pH values, with the minimum
values observed at a pH of 8. All sample test blanks are below the method
detection limit of 0.0005 mg/L, indicating cross-contamination of the
experimental samples is not evident. Laboratory QC data associated with the
reported mercury results are presented and discussed in Section 5.2.
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Table 3.4 Constant pH Leaching Results for Untreated Catalyst1
2 hr
10 hr
24 hr
Blank
Mercury (mg/L)
pH 2
13.8
19.2
17.6
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3.5.3 Results
Table 3.5 summarizes the reported mercury concentrations for each pH
test. Leaching of the spent catalyst lowered the pH of all leachate samples,
except for the test carried out at a pH of 12. The pH 12 test also produced a
significantly higher mercury concentration relative to the other tests.
Observation of the mercury concentrations and corresponding pH values
indicates that there is no positive or negative trend between the two
parameters. These results are somewhat different than those reported in
Section 3.4, where a minimum mercury concentration is observed to occur at
a pH of 8. Other notable observations on the data in Table 3.5 are the poor
replication of results for the pH 10 test and the high mercury concentration
measured in the blank. Poor replication of the pH 10 test may indicate
heterogeneity in the distribution of mercury in the spent catalyst, which may
also account for the scatter of measured concentrations across the tested pH
range. The elevated mercury concentration in the experimental blank indicates
that some cross-contamination may be present in the reported results, although
this is not a significant bias given the high mercury concentrations reported for
the leachate samples. Laboratory QC data associated with the reported
mercury results are presented and discussed in Section 5.2.
Table 3.5 RU-SR002.1 Leaching Results for Untreated Catalyst1
Initial pH
Final pH
Mercury (mg/L)
Initial pH
Final pH
Mercury (mg/L)
12
12.9
190
6
3.29
19.4
11
8.28
15.1
5
3.41
16.3
10
7.87
17.6
27.7<2)
4
2.17
14.8
9
6.41
29.7
3
0.89
59.1
59.0<2)
8
4.69
23.3
Natural
2.10
10.4
7
3.95
22.8
Blank
5.47
0.38
(1) Mercury analysis performed by Environmental Enterprises Incorporated, Cincinnati, Ohio
(2) Indicates test duplicate
(3)As received.
10
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4.0 Stabilization Treatments
4.1 Stabilization ofBCP Spent Catalyst by Sulfide
4.1.1 Introduction
Sulfide is one of the most widely used reactants for stabilizing mercury
waste streams because of the low solubility of mercuric sulfide. The mechanism
of sulfide-induced treatment is expected to be precipitation. However, due to the
complexity of mercury-sulfide chemistry and the compositional variability in
mercury waste streams, the process of sulfide-induced stabilization of mercury
wastes has not been sufficiently developed. Therefore, further research is needed
to optimize process-controlling parameters. In this study, pH and sulfide dosage
were varied to test their effects on the stabilization of spent BCP mercuric
chloride catalyst.
4.1.2 Procedure
The procedure and test matrix for sulfide stabilization of spent BCP
mercuric chloride catalyst is briefly described below:
1. Weigh 20 g of catalyst (approximately 431 mg of mercury) and an amount of
Na2S-9H2O sufficient to meet the indicated S/Hg molar ratio (Table 4.1).
Place the solids into HDPE bottles.
2. Add 200 mL of deionized Ultra-filtered (D.I.U.F) water into the bottles (a
liquid/solid mass ratio of approximately 10 is maintained due to the
complete dissolution of the sodium sulfide).
3. Adjust the pH of the above mixtures to the initial pH values (2, 4, 6, 8 and
10) using IN NaOH and/or 2N HNO3
4. Tumble the mixtures for 24 hours and then take a final pH measurement.
5. Filter the mixtures through a 0.45 mm glass fiber filter and collect a 100 mL
filtrate sample.
6. Acidify the sample to a pH of less than 2 with HNO3 and store at 4°C (up to
28 days) until analyzed for total mercury by CVAAS.
11
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7. Dry the filter cakes (i.e., the stabilized spent catalyst) in an oven at 40 °C
until the mass is stable to within +/- 0.01 g (overnight is generally sufficient
to obtain the required control).
8. Weigh 10 g of the stabilized and dried spent catalyst and submit the samples
for TCLP testing and analysis by CVAAS.
Table 4.1 Sample Test Matrix
S/Hg Ratio
0 (Blank)
1
3
5
7
pH 2
X
X
X
X
X
pH4
X
X
X
X
X
pH6
X
X
X
X
X
pH 8
X
X
X
X
X
pH 10
X
X
X
X
X
4.1.3 Results
Table 4.2 and Figure 4.1 summarize the results for sulfide-stabilized BCP
spent catalyst. Experimental duplicates were runfor S/Hg = 3/pH = 6 and S/Hg
= 5/pH = 4 (Table 4.2). Results are expressed as measured mercury concentration
in the leachate and as the percent of total mercury leached from the untreated and
treated spent catalyst [e.g., ((92.8 mg/L * 0.2 L) / 431 mg) * 100 = 4.31 %].
Mercury concentrations in the filtered leachate obtained from treated spent
catalyst are well below those obtained from the untreated waste, with the
exception of the pH 8 and 10 results for a S/Hg molar ratio of 3. The anomalous
mercury value of 207 mg/L for these two samples exceeds the highest mercury
value reported for leachate obtained from the untreated waste, indicating
problems may have occurred with filtration of the samples. Therefore, these data
points are rejected. Laboratory QC data and experimental duplicates associated
with the reported mercury results are presented and discussed in Section 5.2.
Below a pH of 5, there is no improvement in the stabilization of mercury
in the spent catalyst when using an S/Hg molar ratio above 3. Above a pH of 5,
analytical results appear to be quite scattered for S/Hg molar ratios of 3,5 and 7.
12
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There are no clear trends toward increasing or decreasing mercury concentrations
over the pH interval of 6 to 10 for the individual S/Hg molar ratios of 3, 5 and 7.
However, there is an overall trend toward decreasing mercury concentrations at
pH 8 and 10 as sulfide increases, suggesting the mercuric sulfide solubility
product is controlling mercury concentrations.
The above observations are also reflected in the calculated values for
percent total mercury released to the leachate. In a 24-hour period, 4.0 to 6.5
percent of the mercury is released to leachate that contacts the untreated waste.
The addition of sulfide to the spent catalyst suppresses the release of mercury to
the leachate for all treated samples, except the two anomalous sample results at
S/Hg = 3. Again, this is consistent with the precipitation of mercuric sulfide from
the leachate as it contacts the treated waste forms.
Table 4.2 Mercury Results for Sulfide Stabilization
| Target | Molar Ratio |
| pH | S/Hg = 0 | S/Hg = 1 | S/Hg = 3 | S/Hg = 5 | S/Hg = 7 |
2
4
6
8
10
pH»»
2.01
4.31
7.12
7.96
9.83
Hg
mg/L'2)
92.8
140
101
86.8
88.1
Hg
%m
4.31
6.50
4.69
4.03
4.09
pH">
1.96
3.93
5.87
7.59
8.86
Hg
mg/L12)
12.3
4.40
3.87
3.71
5.93
Hg
%'"
0.571
0.204
0.180
0.173
0.276
pH">
2.02
3.38
3.99
7.83
9.36
Hg
mg/L'2)
0.0310
0.0129
13.6 '"
13.9
207
207
Hg
%'"
0.001
0.001
0.635
9.61
9.61
pH"'
2.14
3.58
5.44
8.68
9.55
Hg
mg/L'2>
0.120
0.0428'4'
0.0402
0.0260
37.3
8.03
Hg
%'"
0.006
0.002
0.001
1.73
0.373
pH">
2.22
4.51
5.40
8.99
9.54
Hg
mg/L12'
0.0314
0.0970
0.266
1.58
0.0561
Hg
%'"
0.001
0.005
0.012
0.073
0.003
(1) The pH values were taken after a 24 hour treatment period.
(2) Concentration in the leachate after filtering.
(3) Percentage of total mercury released from untreated (S/Hg = 0) and treated spent catalyst.
(4) Test duplicates.
13
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1000
I
£
u
El
O
hi
K
0.01
5 6 7 8 9
pH of Stabilization
10 11 12
Figure 4.1 Mercury Results for Sulfide Stabilization as a function of stabilization pH
Table 4.3 and Figure 4.2 show the efficiency of the sulfide-stabilization process based
on the percentage of total mercury released from the untreated and treated waste. The
stabilization efficiency is defined as:
(°/° Hguntreatedwaste- %Hgtreated waste) / (%Hguntreated waste) * 100%
The efficiency calculations indicate that treatment of the spent catalyst with sodium
sulfide is very effective in lowering mercury concentrations in the leachate. In general, over 90
percent of the mercury released from the untreated waste was retained in the treated waste, with
three exceptions noted in Table 4.3. Approximately half of the treated samples retained over
99 percent of the mercury released from the untreated waste.
14
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Table 4.3 Stabilization Efficiency (%
Target
pH
2
4
6
8
10
Molar Ratio
S/Hg = 1
pH(1)
1.96
3.93
5.87
7.59
8.86
Efficiency
86.75
96.86
96.17
95.73
93.27
S/Hg = 3
pH(1)
2.02
3.38
3.99
7.83
9.36
Efficiency
99.97
99.99
86.44
(2)
(2)
S/Hg = 5
pH(1)
2.14
3.58
5.44
8.68
9.55
Efficiency
99.87
99.97
99.97
57.03
90.89
S/Hg = 7
pH(1)
2.22
4.51
5.40
8.99
9.54
Efficiency
99.97
99.93
99.74
98.18
99.94
(1) The pH values are taken after a 24 hour treatment period.
(2) Efficiency cannot be calculated due to rejected data points.
56789
pH of Stabilization
10 11 12
Figure 4.2 Stabilization efficiency(%)
TCLP results for mercury are shown in Table 4.4 and on Figure 4.3. Experimental
duplicates were run for S/Hg = 0/pH = 6 and S/Hg = 3/pH = 6 (Table 4.4). At S/Hg molar ratios
of 1, 3 and 7, mercury concentrations generally decreased as pH increased, whereas this trend
is not evident for results associated with S/Hg = 5. Although the sulfide treatment substantially
lowers the mercury concentrations relative to untreated samples, only 5 samples (bold boxes in
Table 4.4) passed the TCLP limit of 0.2 mg/L. Results might be improved if the treated solids
were dried at 100°C, rather than 40°C, prior to undergoing TCLP testing. A higher drying
temperature might promote a higher degree of crystallinity in the mercuric chloride precipitate,
with an expected decrease in the amount of mercury leached from the solid. Laboratory QC data
15
-------
and experimental duplicates associated with the reported mercury results are presented and
discussed in Section 5.2.
Table 4.4 TCLP Mercury Results (mg/L) for Sulfide Stabilization
Target
pH
2
4
6
8
10
Molar Ratio
S/Hg = 0
pH(1)
2.01
4.31
7.12
7.96
9.83
TCLP Hg
129
160
130 <2'
150
139
128
S/Hg=l
pH(1)
1.96
3,93
5.87
7.59
8.86
TCLP
Hg
57.5
52.9
39.0
39.7
37.5
S/Hg = 3
pH(1)
2.02
3.38
3.99
7.83
9.36
TCLP Hg
13,4
8.34
4.22 (2>
4.09
7.55
3.01
S/Hg = 5
pH(1)
2.14
3.58
5.44
8.68
9.55
TCLP
Hg
2.27
0.191
0.343
1.51
0.531
S/Hg = 7
pH(1)
2.22
4.51
5.40
8.99
9.54
TCLP Hg
0.476
0.161
0.191
0.0336
0.0185
(l)The pH values are taken after a 24 ho ur treatment period and represent the pH of the treatment mixture
prior to drying the solid and conducting the TCLP test.
(2) Test duplicates.
200 -
ifin «
5 /"^ ^ ^-^ __
a ro ^ ~~*
**-s
a
« 80
hJ
u
H 40
A—- A .
-\ I* 1 •— T — * 1— ;* 1 1 1 * /P*B i i i
1 2 3 4 5 6 7 8 9 10 11 12
pH of Stabilization
— * — S/Hg=0
S/Hg=l
^*^S/Hg=3
^»^S/Hg=5
^^S/Hg=7
Figure 4.3 TCLP Mercury Results for Sulfide Stabilization
16
-------
Stabilization efficiencies for the TCLP results are shown in Table 4.5 and in Figure 4.4.
The efficiency was calculated as noted above. Except for the stabilization scenarios with S/Hg
= 1, the stabilization efficiencies were higher than 90% for all other S/Hg molar ratios.
However, the most successful treatment is noted at neutral to high pH for S/Hg = 7, as all these
samples passed the TCLP test (Table 4.4).
Table 4.5 Stabilization Efficiency for TCLP Data
Target
pH
2
4
6
8
10
Molar Ratio
S/Hg = 1
pH(1)
1.96
3,93
5.87
7.59
8.86
Efficiency
55.43
66.52
74.34
71.44
72.01
S/Hg = 3
pH(1)
2.02
3,38
3,99
7.83
9.36
Efficiency
89.61
94.55
97.37
94.57
97.72
S/Hg = 5
pH(1)
2.14
3.58
5.44
8.68
9.55
Efficiency
98.25
99.88
99.78
98.89
99.59
S/Hg = 7
pH(1)
2.22
4.51
5.4
8.99
9.54
Efficiency
99.64
99.90
99.88
99.97
99.99
(1) The pH values are taken after a 24 hour treatment period and represent the pH of the treatment
mixture prior to drying the solid and conducting the TCLP test.
^
a
o
£ ^
w ^
a >— '
o
.a
i
£
Hg Stabilization Efficiency
Calculated from TCLP Hg
tin
100
90
80
70
60
en
Afi
123 45678 9 10 11
pH of Stabilization
S/Hg = 1
-+- S/Hg = 3
-^- S/Hg = 5
-x- S/Hg = 7
Figure 4.4 Stabilization Efficiency for TCLP Data
17
-------
4.1.4 Discussion
Mercuric sulfide (HgS) is very insoluble in water, with a solubility
product (Ks) of 10"52 (Bard, 1966)1. However, the solubility of HgS in water can
be increased by association with various hydrogen sulfide species to form a
number of mercuric-hydrogen-sulfide ions that enhance the solubility of HgS in
water (Clever et a/., 1985)2. These associations can lead to the formation of
HgS-2H2S°, Hg(HSV, HgS-2HS', and HgS22' (Figure 4.5). HgS-2H2S° is the
dominant aqueous specie at pH values less than 6.2, while Hg(HS)3" is the
dominant form between the pH values of 6.2 and 7. HgS-2HS" is the most
abundant mercury complex between the pH of 7 and 8.3, and HgS22" dominates
above a pH of 8.3. In fact, the concentration of HgS22" increases linearly with
the hydroxyl ion concentration for pH values over 8.3 (Figure 4.5).
According to Figure 4.5, mercury and sulfide reach their highest
concentrations above neutral pH by forming complexes with HS" and S2".
However, the results in Figure 4.5 cannot be reconciled with the experimental
results because some of the lowest mercury concentrations were measured at pH
8 and 10 when the S/Hg molar ratio was 7 (1.58 and 0.056 mg/L, Table 4.2).
This observation may indicate that the sulfide-stabilization did not reach
equilibrium within the 24 hour period. Based on our preliminary research on
the formation kinetics of sulfide and mercury surrogates(data not report here),
sulfide-stabilization of mercury waste cannot reach equilibrium within 24 hours
when high pH and high sulfide dosage are applied. Therefore, a much longer
reaction time is recommended for future research.
'Bard, A.J., Chemical Equilibrium, Harper and Row, Publishers, New York, 1966. D
Clever, H.L., S.A. Johnson, and M.E. Derrick, "The Solubility of Mercury and Some SparinglyD
Soluble Mercury Salts in Water and Aqueous Electrolyte Solutions," J. Phy s. Chem. Ref. Data, Vol. D
14, No. 3, 1985.D
18
-------
-5.QO
-LOO
•-2OQ
4.O
IQ.O
Figure 4.5 Distribution of the various Hg-H-S species as a function of pH
4.2 Stabilization of BCP Spent Catalyst by Phosphate
4.2.1 Introduction
Phosphates have been shown to be effective in stabilizing heavy metals (Cotter-
Howells et.al, 19961; Eighmy et.al, 19972; Ma et.al., 19953; O'Hara et.al., 19884).
Mercury phosphates also have very low solubility (Qvarfort-Dahlman, 19755; Clever
et.al., 19856). However, there has been little work done on phosphate-stabilization of
mercury waste forms. This experiment was designed to investigate the effect of
phosphate on mercury stabilization. In this experiment, variables such as pH and
phosphate dosage were tested for their effects on phosphate-induced BCP catalyst
stabilization.
19
-------
4.2.2 Procedure
The procedure and test matrix for phosphate stabilization of spent BCP mercuric
chloride catalyst is briefly described below:
1. Weigh 20 g of catalyst (approximately 431 mg of mercury) and an amount
of NajHPCW sufficient to meet the indicated P/Hg molar ratio (Table 4.6).
Place the solids into HDPE bottles.
2. Add 200 mL of D.I.U.F water into the bottles (a liquid/solid mass ratio of
approximately 10 is maintained due to the complete dissolution of the
sodium phosphate).
3. Adjust the pH of above mixtures to the initial pH values (3,6, 8,10 and 12)
using IN NaOH and/or 2N HNO3
4. Tumble the mixtures for 24 hours and then take a final pH measurement.
5. Filter the mixtures through a 0.45 mm glass fiber filter and collect a 100
mL filtrate sample.
6. Acidify the sample to a pH of less than 2 with HNO3 and store at 4°C (up
to 28 days) until analyzed for total mercury by CVAAS.
7. Dry the filter cakes (i.e., the stabilized spent catalyst) in an oven at 40 °C
until the mass is stable to within +/- 0.01 g (overnight is generally
sufficient to obtain the required control).
8. Weigh 10 g of the stabilized and dried spent catalyst and submit the
samples for TCLP testing and analysis by CVAAS.
4.2.3 Results
Table 4.6 and Figure 4.6 summarize results for the phosphate treatment of spent
mercuric chloride catalyst. Experimental duplicates were run for P/Hg = 0.5/pH = 8 and P/Hg
= 1/pH = 10 (Table 4.6). The measured mercury concentrations indicate that the addition of
phosphate has virtually no effect on stabilizing mercury in the waste form. Over the pH range
tested, mercury concentrations in the leachate derived from treated samples were close to those
of untreated (P/Hg = 0) samples. Laboratory QC data and experimental duplicates associated
with the reported mercury results are presented and discussed in Section 5.3.
20
-------
ocn
J ncn .
DJ
900 -
t?
c
o i^n
tJ iau -
DJ
1100 -
0 -
/{j>
/$
^^1^^ Xx^
"^^^^^
-+- P/Hg=0
P/Hg=0.1
^i^ P/Hg=0.5
-•- P/Hg=1
-»- P/Hg=0.3
0 1 2 3 4 5 6 7 8 9 10 11 12 13
pH of Stabilization
Figure 4.6 Mercury Results (mg/L) for Phosphate Stabilization
Table 4.6 Mercury Results for Phosphate Stabilization
Molar Ratio
Target
pH
2
4/3
6
8
10
12
P/Hg=0
pH(1)
2.01
4.31
7.12
7.96
9.83
12.00
Hg
mg/L<2)
92.8
140
101
86.8
88.1
222
P/Hg=0.1
pH(1)
3.12
5.95
7.89
9.68
12.01
Hg
mg/L<2)
107
127
107
88.9
290
P/Hg=0.3
pH(1)
3.19
6.33
7.93
9.83
12.00
Hg
mg/L(2)
95.4
100
89.1
99
244
P/Hg=0.5
pH(1)
3.22
5.9
7.87
9.67
11.93
Hg
mg/L<2)
115
100
96.2 (3
84.5
79.5
230
P/Hg=l
pH(1)
3.06
5.56
7.71
9.32
12.11
Hg
mg/L(2)
104
110
92.8
123(3)
117
252
(l)The pH values are taken after a 24 hour treatment period.
(2) Concentration in the leachate after filtering.
(3) Test duplicates.
21
-------
Table 4.7 and Figure 4.7 show TCLP results for phosphate-stabilized catalyst.
Experimental duplicates were run for P/Hg = 0.5/pH = 8 and P/Hg = 1/pH = 10 (Table 4.7).
Obviously, all samples failed the TCLP test. Phosphate-stabilized samples have
approximately the same TCLP results as the untreated catalyst. Laboratory QC data and
experimental duplicates associated with the reported mercury results are presented and
discussed in Section 5.3.
ocn
ZDU
onfi
ZUU
_;
Bi
E-i ^ri
1 DU
tj
c
S -i nn
u I UU
O)
I
en
DU
n
x-""^*
.x ^jv^
<^^'^S^>^.
*~~^ '\\ »
\
-+- P/Hg=0
P/Hg=0.1
-i- P/Hg=0.3
-^- P/Hg=0.5
-s.e- P/Hg=1
u n i i i i i i i i i i i i
0 1 2 3 A 5 6 7 8 9 10 11 12 13
pH of Stabilization
Figure 4.7 TCLP Mercury (mg/L) Results for Phosphate Stabilization
22
-------
Table 4.7 TCLP Mercury (mg/L) Results for Phosphate Stabilization
[
Molar Ratio
3
6
8
10
12
P/Hg=0
145
140
139
128
101
P/Hg=0.1
159
172
172
173
105
P/Hg=0.3
123
148
104
115
69.7
P/Hg=0.5
176
213
137 <"
123
133
99
P/Hg=l
169
163
173
118("
135
53.7
(1) Test duplicates
4.2.4 Discussion
The spent mercuric chloride catalyst will release chloride ions during the
leaching tests. It has been reported that the presence of chloride ion decreases the
formation of mercury phosphate precipitates (Feicket.aL, 19727; Wang et.al., 19918),
due to the formation of strong aqueous mercury chloride species. This is hypothesized
to be the reason why the phosphate treatment was ineffective in this study. Although
the same mercury chloride species form in the presence of the sulfide-treated waste, the
very low solubility of HgS appears to overcome the association constants of the
aqueous mercury chloride
species.
23
-------
5.0 Data Quality
5.7 Background Characterization
Table 5.1 summarizes the laboratory QC data for the total mercury and
TCLP results reported in Tables 2.1 and 3.3. The calibration curve was established
using mercury standards of 0.50, 2.00, 5.00, 10.00 and 40.00 mg/L, with a
corresponding correlation coefficient of 0.9998. Initial and continuing calibration
standards and the LCS (Laboratory Control Sample) were within the laboratory
control limit of 85 to 115 percent. The initial and continuing blank samples were all
below the reporting detection limit of 0.0005 mg/L. Results for the laboratory
duplicate and spike are within the stated QAPP control limits of ±25 percent
(duplicate) and 75 to 125 percent (spike recovery).
5.2 Leaching Tests
Table 5.2 summarizes the laboratory QC data for the total mercury results
reported in Table 3.1. The calibration curve was established using mercury standards
of 0.50, 2.00, 5.00, 10.00 and 40.00 mg/L, with a corresponding correlation
coefficient of 0.9996. Initial and continuing calibration standards and the LCS were
within the laboratory control limit of 85 to 115 percent. The initial and continuing
blank samples were all below the reporting detection limit of 0.0005 mg/L. Results
for the laboratory duplicate and spike are within the stated QAPP control limits of
±25 percent (duplicate) and 75 to 125 percent (spike recovery).
Table 5.3 summarizes the laboratory QC data for the total mercury results
reported in Table 3.4. The calibration curve was established using mercury standards
of 0.50, 2.00, 5.00, 10.00 and 40.00 mg/L, with a corresponding correlation
coefficient of 0.9999. Initial and continuing calibration standards and the LCS were
within the laboratory control limit of 85 to 115 percent. The initial and continuing
blank samples were all below the reporting detection limit of 0.0005 mg/L. Results
24
-------
for the laboratory duplicate are within the stated QAPP control limit of ±25 percent.
A post-digestion spike was not reported for this batch of samples.
Table 5.1 Laboratory QC Data for EEI Total & TCLP Mercury Results
Background Data
Sample ID
True
mg/L
Found
mg/L
PereenRPD]
Recover^ |
Dilution
Factor
Reported Result
mg /kg (mg /L)
Work Order 80-04-319: Total Mercury Results
ICV
CCV1
CCV2
CCV3
CCV4
LCS
ICB
CCB1
CCB2
CCB3
CCB4
01A
OlA-duplicate
05A-spike
5.00
5.00
5.00
5.00
5.00
10.00
<0.50
<0.50
O.50
<0.50
<0.50
na
na
5.00
5.18
4.89
4.82
4.84
4.87
10.34
<0.50
<0.50
<0.50
<0.50
<0.50
6.68
5.03
5.36
104
97.8
96.4
96.8
97.4
103
na
na
na
na
na
na
na
107na
na
na
na
na
na
na
na
na
na
na
na
98 9
na
na
na
na
na
na
na
na
na
na
na
100,000
100,000
na
na
na
na
na
na
na
na
na
na
na
na
668,000
503,000
na
Work Order 80-04-31 9: TCLP Mercury Results
ICV
ccvi
CCV2
CCV3
CCV4
LCS
ICB
CCB1
CCB2
CCB3
CCB4
22A
22A-duplicate
22A-spike
5.00
5.00
5.00
5.00
5.00
10.00
<0.50
O.50
<0.50
<0.50
<0.50
na
na
5.00
5.13
5.02
5.10
5.50
4.97
10.80
<0.50
<0.50
<0.50
<0.50
<0.50
12.08
11.86
6.03
103
100
102
110
99.4
108
na
na
na
na
na
na
na
121
na
na
na
na
na
na
na
na
na
na
na
1 84
na
na
na
na
na
na
na
na
na
na
na
na
10,000
10,000
na
na
na
na
na
na
na
na
na
na
na
na
(121,000)
(119,000)
na
na = not applicable
Lab reports that a spike was run on diluted sample, post digestion
25
-------
Table 5.2 Laboratory QC Data for EEI Total Mercury Result
Solid Stability in Water
Sample ID
True
ng/L
Found
mg/L
PercenRPD
Reco\^
ry
Dilution
Factor
Reported Result
mg/L
Work Order 99-10-276: Total Mercury Results
icv
CCVl
CCV2
LCS
ICB
CCB1
CCB2
05A
OSA-duplicate
05A-spike
5.00
5.00
5.00
10.00
<0.50
<0.50
<0.50
na
na
0.00
4.94
4.62
4.62
9.91
0.53
<0.50
<0.50
3.14
3.15
9.01
98.8
92.4
92.4
99.1
na
na
na
na
na
90.1na
na
na
na
na
na
na
na
0.32
na
na
na
na
na
na
na
2
2
na
na
na
na
na
na
na
na
6.28
6.30
na
na = not applicable
Table 5.3 Laboratory QC Data for EEI Total Mercury Result
University of Cincinnati pH Test
Sample ID
True
mg/L
Found
mg/L
PercerRPD
Recove*^
Dilution
Factor
Reported Result
mg/L
Work Order 99-10-211: Total Mercury Results
ICV
CCVl
CCV2
CCV3
CCV4
CCV5
LCS
ICB
CCB1
CCB2
CCB3
CCB4
CCB5
27A
27A-duplicate
5.00
5.00
5.00
5.00
5.00
5.00
10.00
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
na
na
4.82
4.81
4.52
4.58
4.45
4.63
9.72
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
0.88
0.90
96.8
96.2
90.4
91.6
89.0
92.6
97.2
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
2.7.5
na
na
na
na
na
na
na
na
na
na
na
na
na
2,000
2,000
na
na
na
na
na
na
na
na
na
na
na
na
na
1,760
1,800
na = not applicable
Lab reports that a spike was not run due to reported result exceeding 1,000 mg /L
Table 5.4 summarizes the laboratory QC data for the total mercury results
reported in Table 3.5. The calibration curve was established using mercury
standards of 0.50, 2.00, 5.00, 10.00 and 40.00 mg/L, with a corresponding
26
-------
correlation coefficient of 0.9998. Initial and continuing calibration standards and
the LCS were within the laboratory control limit of 85 to 115 percent. The initial
and continuing blank samples were all below the reporting detection limit of 0.0005
mg/L. Results for the laboratory duplicate and spike are within the stated QAPP
control limits of ±25 percent (duplicate) and 75 to 125 percent (spike recovery).
Table 5.4 Laboratory QC Data for EEI Total Mercury Result
Rutgers University pH Test
Sample ID
i
True
ng/L
Found
mg/L
PercerRPD
Recover^
Dilution
Factor
Reported Result
mg/L
Work Order 99-12-045: Total Mercury Results
ICV
CCVl
CCV2
CCV3
LCS
ICB
CCB1
CCB2
CCB3
01A
OlA-duplicate
OlA-spike
5.00
5.00
5.00
5.00
10.00
<0.50
<0.50
<0.50
<0.50
na
na
5.00
4.81
4.66
4.75
4.63
10.40
<0.50
<0.50
<0.50
<0.50
8.95
10.00
4.65
96.2
93.2
95.0
93.0
104
na
na
na
na
na
na
93.0
na
na
na
na
na
na
na
na
na
1 1.1
na
na
na
na
na
na
na
na
na
na
20,000
20,000
na
na
na
na
na
na
na
na
na
na
179,000
200,000
na
na = not applicable
Lab reports that a spike was run on diluted sample, post digestion
5.3 Acidity
Prior to the titration, the pH meter was calibrated using a two-point
calibration with certified calibration standards, pH 4 and pH 10. The calibration
efficiency is defined as the measured value divided by the known value, and the
value of 1.02 is in the range of 1.05 to 0.95, per the QAPP.
5.4 Treatment Reagents
Table 5.5 summarizes the laboratory QC data for the total mercury results
reported in Tables 4.2 and 4.6. The calibration curves were established using
mercury standards of 0.50, 2.00, 5.00, 10.00 and 40.00 mg/L, with corresponding
27
-------
correlation coefficients of 0.999665 and 999693. Initial and continuing calibration
standards and the LCS were within the laboratory control limit of 85 to 115 percent.
The initial and continuing blank samples were all below the reporting detection limit
of 0.0005 mg/L. Results for the laboratory duplicate and spike are within the stated
QAPP control limits of ±25 percent (duplicate) and 75 to 125 percent (spike
recovery).
28
-------
Table 5.5 Laboratory QC Data for EEI Total Mercury Result
Sulfide and Phosphate Stabilization
Sample ID
True
mg/L
Found
mg/L
Percent
Recovery
RPD
%
Dilution
Factor
Reported
Result
mg/L
Work Order 80-05-219: Total Mercury Results
ICV
ccvi
CCV2
CCV3
CCV4
CCV5
CCV6
LCS
ICB
CCB1
CCB2
CCB3
CCB4
CCB5
CCB6
07A
07A-duplicate
07A-spike
ICV
CCVI
CCV2
CCV3
CCV4
CCV5
CCV6
CCV7
CCV8
CCV9
LCS
LCS
ICB
CCB1
CCB2
CCB3
CCB4
CCB5
CCB6
CCB7
CCB8
CCB9
24A
24A-duplicate
24A-spike
5.00
5.00
5.00
5.00
5.00
5.00
5.00
10.00
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
na
na
50.0
5.00
5.00
5.00
5.00
5.00
5.00
5.00
5.00
5.00
5.00
10.00
10.00
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
na
na
5.00
4.86
5.15
4.92
4.63
4.90
4.75
4.65
10.60
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
22.24
22.13
57.7
5.15
4.62
5.15
4.99
4.79
5.19
4.97
4.89
4.96
5.07
9.62
10.06
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
7.56
8.51
5.37
97.2
103
98.4
97.8
98.0
95.0
93.0
106
na
na
na
na
na
na
na
na
na
115
103
92.4
103
99.8
95.8
104
99.4
97.8
99.2
101
96.2
101
na
na
na
na
na
na
na
na
na
na
na
na
107
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
0.495
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
11.8
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
10,000
10,000
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
1,000
1,000
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
222,000
221,000
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
7,560
8,510
na
29
-------
45A
45A-duplicate
45A-spike
na
na
5.00
11.77
11.67
5.78
na
na
116
n XST,
na
10,000
10,000
na
118,000
117,000
na
na = not applicable
Lab reports that a spike was run on diluted sample, post digestion
Table 5.6 summarizes the laboratory QC data for the TCLP mercury results
reported in Tables 4.4 and 4.7. The calibration curves were established using
mercury standards of 0.50, 2.00, 5.00, 10.00 and 40.00 mg/L, with corresponding
correlation coefficients of 999693 (Work Order 80-050219), 999691 and 999836.
Initial and continuing calibration standards and the LCS were within the laboratory
control limit of 85 to 115 percent. The initial and continuing blank samples were
all below the reporting detection limit of 0.0005 mg/L. Results for the laboratory
duplicate and spike are within the stated QAPP control limits of ±25 percent
(duplicate) and 75 to 125 percent (spike recovery).
Table 5.7 summarizes the experimental precision associated with the results
for test duplicates (Tables 4.2, 4.4, 4.6 & 4.7). The precision between test
duplicates is better than ±15 percent, which exceeds the precision required for
duplicate analytical measurements. Therefore, the experimental reproducibility is
considered acceptable.
30
-------
Table 5.6 Laboratory QC Data for EEI TCLP Mercury Result
Sulfide and Phosphate Stabilization
Sample ID
True
mg/L
Found
mg/L
PercenBLPD
Recovei^
Dilution
Factor
Reported Result
mg /L
Work Order 80-05-219: TCLP Mercury Results
ICV
CCV1
CCV2
CCV3
CCV4
CCV5
CCV6
LCS
ICB
CCB1
CCB2
CCB3
CCB4
CCB5
CCB6
42A
42A-duplicate
42A -spike
5.00
5.00
5.00
5.00
5.00
5.00
5.00
10.00
<0.50
<0.50
<0.50
<0.50
O.50
<0.50
<0.50
na
na
500
4.86
5.15
4.92
4.63
4.90
4.75
4.65
9.83
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
1.65
1.60
450
97.2
103
98.4
97.8
98.0
95.0
93.0
106
na
na
na
na
na
na
na
na
na
90.0
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
•* 07
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
100,000
100,000
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
165,000
160,000
na
Work Order 80-05-218: TCLP Mercury Results
ICV
ccvi
CCV2
CCV3
CCV4
LCS
LCS
ICB
CCB1
CCB2
CCB3
CCB4
01A
OlA-duplicate
OlA-spike
16A
16A-duplicate
16A-spike
ICV
CCVI
CCV2
CCV3
CCV4
CCV5
CCV6
LCS
LCS
ICB
CCB1
CCB2
CCB3
CCB4
CCB5
CCB6
5.00
5.00
5.00
5.00
5.00
10.00
10.00
<0.50
<0.50
<0.50
<0.50
<0.50
na
na
5.00
na
na
5.00
5.00
5.00
5.00
5.00
5.00
5.00
5.00
10.00
10.00
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
5.18
5.23
5.04
4.97
4.98
9.87
9.92
<0.50
<0.50
<0.50
<0.50
<0.50
1.37
1.21
5.38
4.25
4.18
5.13
5.11
5.14
5.19
5.21
5.04
5.00
4.93
10.06
10.08
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
<0.50
104
105
101
99.4
99.6
98.7
99.2
na
na
na
na
na
na
na
108
na
na
103
102
103
104
104
101
100
98.6
106
108
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
124
na
1 66
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
100,000
100,000
na
1,000
1,000
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
137,000
121,000
na
4,250
4,180
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
31
-------
31A
31A-duplicate
31A-spike
41A
41A-duplicate
41A-spike
na
na
5.00
na
na
5.00
1.66
1.75
5.13
1.67
1.70
4.94
na
na
103
na
na
98.8
<\ if.
na
1 78
na
100,000
100,000
na
100,000
100,000
na
166,000
175,000
na
167,000
170,000
na
na = not applicable
Lab reports that a spike was run on diluted sample, post digestion
Table 5.7 Experimental QC Data for Test Duplicates
Sulfide and Phosphate Stabilization
Sample ID [True
|ng/L
Found
mg/L
Work Order 80-05-219: Total Mereur
15
16
20
21
na
na
na
na
13.57
13.89
42.84
4.02
PereerRPD]
Recove^ |
Dilution
Factor
Reported Result
mg/L
y Results for Sulfide Stabilization (Table 4 2)
na
na
na
na
2.33
6.79
1,000
1,000
1
10
13,600
13,900
42.8
40.2
Work Order 80-05-218: TCLP Mercury Results for Sulfide Stabilization (Table 4.4)
3
4
15
16
na
na
na
na
1.30
1.50
4.09
4.22
na
na
na
na
Work Order 80-05-219: Total Mercury Results for Phos
37
38
44
45
na
na
na
na
9.62
8.45
12.34
11.72
na
na
na
na
14.3
3.13
100,000
100,000
1,000
1,000
130,000
150,000
4,090
4,220
phate Stabilization (Table 4.6)
13.0
5.15
10,000
10,000
10,000
10,000
96,200
84,500
123,000
117,000
Work Order 80-05-218: TCLP Mercury Results for Phosphate Stabilization (Table 4.7)
44
45
37
38
na
na
na
na
1.18
1.35
1.37
1.23
na
na
na
na
13.4
10.8
100,000
100,000
100,000
100,000
118,000
135,000
137,000
123,000
na = not applicable
32
-------
6.0 Conclusions
It is concluded from the sulfide-stabilization results that the addition of
sodium sulfide to spent BCP mercuric chloride catalyst substantially reduces the
amount of mercury released from the waste when it is leached. Mercury stabilization
efficiencies exceeded 99 percent and passed the TCLP test at pH values of 4, 6, 8
and 10 at a S/Hg molar ratio of 7. The treatment performance might be increased
by allowing more reaction time between the sulfide/waste mixture and by increasing
the drying temperature of the treated solid prior to running the TCLP test.
Phosphate failed to effectively stabilize mercury in the BCP spent catalyst.
It is hypothesized that the high concentration of chloride ion in the leachate
decreases the formation of mercury phosphate precipitates, due to the formation of
a strong aqueous mercury chloride complex.
Cotter-Howells, J. and Caporn, S., "Remediation of contaminated land by formation of heavy
metal phosphates," Applied Geochemistry, 11,335-342, 1996.
2Eighmy, T.T., Crannell, B.S., Butler, L.G., Cartledge, F.K., Emery, E.F., Oblas, D., Krzanowski,
J.E., Eusden, J.D., Jr., Shaw, E.L., and Francis, C.A., "Heavy metal stabilization in municipal
solid waste combustion dry scrubber residue using soluble phosphate," Environmental Science
and Technology, 31, 3330-3338, 1997.
3Ma, Q. Y., Logan, T. J. and Traina, S. J., "Lead immobilization from aqueous solutions and
contaminated soils using phosphate rocks," Environmental Science and Technology, 29, 1118-
1126, 1995.
4O'Hara, M.J. and Surgi, M.R., "Immobilization of lead and cadmium in solid residues from the
combustion of refuse using lime and phosphate," U.S. Patent No. 4,737,356, 1988.
5Qvarfort-Dahlman, I., "On some phosphate equilibria," Chemica Scripta, 8(3), 112-125, 1975.
6Clever, H.L., Johnson, S.A., and Derrick, M.E., "The solubility of mercury and some sparingly
soluble mercury salts in water and aqueous electrolyte solutions," J. Phys. Chem. Ref. Data,
14(3), 631-680, 1985.
7Feick, G., Home, R.A., and Yeaple, D., "Release of mercury from contaminated freshwater
sediments by the runoff of road deicing salt," Science, 175, 1142-1143, 1972.
33
-------
8Wang, J.S., Huang, P.M., Liaw, W.K., and Hammer, U.T., "Kinetics of the desorption of
mercury from selected freshwater sediments as influenced by chloride," Water, Air, and Soil
Pollution, 56, 533-542, 1991.
34
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