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

-------
         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

-------
                     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

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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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