DEVELOPMENT OF A POLYMERIC CEMENTING AND ENCAPSULATING
PROCESS FOR MANAGING HAZARDOUS WASTES
By
H. R. Lubowitz
R. L. Derham
L. E. Ryan
G. A. Zakrzewski
CONTRACT NO. 68-03-2037
Program Manager: H. R. Lubowitz
EPA Project Officer: C. Wiles
Environmental Protection Agency
Cincinnati, Ohio 45268
Prepared for
Environmental Protection Agency
TRW
rnrtm i
ONE SPACE PARK REDONDO BEACH CALIFORNIA 90278
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DEVELOPMENT OF A POLYMERIC CEMENTING AND ENCAPSULATING
PROCESS FOR MANAGING HAZARDOUS WASTES
By
H. R. Lubowitz
R. L. Derham
L. E. Ryan
G. A. Zakrzewski
CONTRACT NO. 68-03-2037
Program Manager: H. R. Lubowitz
EPA Project Officer: C. Wiles
Environmental Protection Agency
Cincinnati, Ohio 45268
Prepared for
Environmental Protection Agency
TRW
SYsriMS **our
ONE SPACE PARK REDONDO BEACH CALIFORNIA 90278
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ABSTRACT
This report provides method, materials, evaluations and engineering
for managing wastes hazardous to man and other life by localization em-
ploying an organic, polymeric cementing and encapsulating process (TRW
process). Specimens, of cubic dimensions three inches on edge, consisting
of wastes cemented with 3 to 4% by weight polybutadiene binder and encap-
sulated by 1/4 inch polyethylene jackets, were fabricated with selected
wastes and subjected to exacting leaching conditions and mechanical testing.
They were found to exhibit excellent retention of contaminants in leaching
by a broad spectrum of aqueous solutions and to withstand degradation under
high compressive and impact mechanical forces.
Engineering study yielded a process flow diagram, a product design, and
examined process economics parametrically. The former included a poten-
tial plant design and mass and energy balances. Cost effective products
were characterized as follows: dimensions, cubic, approximately two feet
on edge; weight, in the range 800 to 1000 pounds; jacket, about 1/4 inch
thick polyethylene resin; encapsulated hazardous waste agglomerate cemented
by 3% w/w polybutadiene resin and jacketed by 4% w/w polyethylene resin.
The cost of waste passivation was estimated at $91 per ton at 20,000 tons
per year throughput. The parametric study related cost to various para-
meters and indicated that the most cost sensitive area was cost of resins,
accounting for approximately 50% of the total cost.
There is a spectrum of difficult to manage hazardous waste for which
the TRW process of agglomeration and polymeric encapsulation appears to be
uniquely applicable. Specific examples of such wastes are: some wastes
contain contaminating compounds in the form of alkali metal salts, e.g.,
sodium metaarsenate, that resist "fixation" by resins (inorganic as well
as organic) and may be readily dispersed by dissolution from resin localized
waste (unencapsulated) into the ecology. Others contain non-soluble com-
pounds such as arsenic trisulfide which may be disseminated by physical
dispersion. In addition, unencapsulated wastes localized satisfactorily
ii
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by resins under certain conditions may, however, maintain resistance to
delocalization over a range of environmental conditions more limited than
that realizable by encapsulation.
This report is submitted in fulfillment of Contract No. 68-03-2037
under the sponsorship of the Environmental Protection Agency. Work was
completed in July 1975.
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TABLE OF CONTENTS
ABSTRACT ii
LIST OF FIGURES vii
LIST OF TABLES x
ACKNOWLEDGMENTS xii
CONCLUSIONS xiii
RECOMMENDATIONS xv
SECTIONS
1. INTRODUCTION 1
2. IDENTIFICATION, SELECTION AND CHARACTERIZATION OF 6
WASTE STREAMS
2.1 WASTE IDENTIFICATION 6
2.2 SELECTION 9
2.3 CHARACTERIZATION 10
3. APPLICATION OF LOCALIZATION PROCESS TO SELECTED WASTES 12
STREAMS
3.1 PROCESS CONCEPT 13
3.2 GENERAL APPLICABILITY 18
3.3 METHOD OF WASTE AGGLOMERATING AND ENCAPSULATING 19
3.3.1 Procedure for Passivation of Wastes 25
3.3.2 Additional Waste Passivation Study 30
3.4 SPECIMENS PREPARED FOR TESTING 33
4. LEACHING TESTS 36
4.1 LEACHING PROCEDURE FOR COMPOSITE HEAVY METAL WASTES 36
4.1.1 Trace Metals Assay Methods 36
4.1.2 Compilation of Test Results 40
4.1.3 Explanation of Leaching Tables 40
iv
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TABLE OF CONTENTS (CONTINUED)
Page
4.2 LEACHING PROCEDURE FOR ARSENIC CONTAINING WASTE 50
4.2.1 Arsenic Assay Method 50
4.2.2 Explanation of Table 52
4.3 ASSAY OF ENCAPSULATED SODIUM CHLORIDE 52
4.4 DISCUSSION OF LEACHING TESTS 52
5. MECHANICAL TESTS 54
5.1 COMPRESSION 54
5.2 FREEZE-THAW TESTING 54
5.3 IMPACT STRENGTH 55
5.4 PUNCTURABILITY 55
5.5 BULK DENSITY 56
5.6 RESULTS OF MECHANICAL TESTING 56
5.7 DISCUSSION OF RESULTS 58
6. DEVELOPMENT OF THE GENERAL PROCESS AND PROCESS ECONOMICS 61
MODEL
6.1 PROCESS DEVELOPMENT 61
6.1.1 Determination of the Dimensional Nature of 63
Products
6.1.2 Process Flow Diagram 67
6.1.3 Mass and Energy Balances 69
6.1.4 Equipment Costs 71
6.2 PROCESS ECONOMICS COMPUTER MODEL 71
6.2.1 Parametric Studies 73
7. IDENTIFICATION OF MANAGEABLE WASTES 90
7.1 METAL MINING 93
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TABLE OF CONTENTS (CONTINUED)
Page
7.2 INDUSTRIAL INORGANIC CHEMICALS 93
7.3 PHARMACEUTICALS 96
7.4 PAINT AND ALLIED PRODUCTS 97
7.5 . ORGANIC CHEMICALS, PESTICIDES, AND EXPLOSIVES 97
7.6 PETROLEUM REFINING 97
7.7 PRIMARY METALS 98
7.8 ELECTROPLATING 98
7.9 PRIMARY AND STORAGE BATTERIES 99
8. FURTHER OBSERVATIONS 102
APPENDIX A AT!
A-1 ORGANIC RESIN ENCAPSULATION A-2
A-2 ENVIRONMENTAL TESTING A-17
APPENDIX B B-l
VI
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FIGURES
No. Page
1 Areas of Application 2
2 Waste 200 Residue (Electroplating Sludge) Magnification ^
100X, Scale Division"0.5 Mil
3 . Waste 700 Residue (Pigment Production Sludge) Magnification 11
100X, Scale Division 0.5 Mil
4 Polybutadiene Coated Residue of Sludge 200 20
5 Fused Residue of Sludge 200 20
6 Polybutadiene Coated Residue of Sludge 300 21
7 Residue of Sludge 300 Fused at 310°F 21
8 Polybutadiene Coated Residue of Sludge 500 22
9 Fused Residue of Sludge 500 22
10 Polybutadiene Coated Residue of Sludge 700 23
11 Fused Residue of Sludge 700 23
12 Polybutadiene Coated Residue of Sludge 900 24
13 Fused Residue of Sludge 900 24
14 Agglomerated Hazardous Waste Residue Emerging from Mold 26
15 Hazardous Waste Agglomerate Positioned for Resin Jacketing 27
16 Agglomerate Submerged in Powdered Polyethylene 27
17 Non-Jacketed Side Seen on the Free Standing Agglomerate 28
After the First Jacketing Step
18 Five-Side Jacketed Agglomerate Resting on Mold Pedestal 28
19 Powdered Polyethylene Seen Free Flowing Under Gravimetric 29
Force
20 Non-Jacketed Side of Agglomerate Seen Positioned for Final 31
Resin Jacketing
21 Encapsulated Hazardous Waste After Final Resin Jacketing 31
Step
vii
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FIGURES (CONTINUED)
Np_. Page
22 Encapsulated Agglomerate Seen After Final Resin Jacketing 32
Step
23 View of Cross Section of Encapsulated Hazardous Waste 32
24 Close-up View of Cross Section of Encapsulated Hazardous 33
Waste, a Blend Described in Section 2.2
25 Cross View of Encapsulated Arsenic Containing Waste 34
26 Polyethylene Jacketed Agglomerates of Sodium Chloride in 34
Cross Section
27 Polyethylene Jacketed Agglomerates of Sodium Chloride in 35
Cross Section
28 Close View of Encapsulated Wastes Under Aqueous Solutions 37
29 Jig Used for Puncturability Testing 57
30 Load-Deflection Curve for Compression Testing of Jacketed 58
Block Specimen
31 Jacketed Specimen After Impact Testing 59
32 Process Concept 62
33 Time Required for Center to Reach 300°F as a Function of 65
Agglomerate Size
34 Oven Volume and Jacketing Resin Required as a Function of 66
Agglomerate Size
35 Process Flow Diagram 70
36 Computer Logic Diagram 74
37 Comparative Effect of Parameter Changes on Operating 80
Cost for the Encapsulation Process
38 Operating Cost as a Function of Plant Size 81
39 Operating Cost as a Function of Raw Material Costs 83
vm
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FIGURES (CONTINUED)
No. Page
40 Operating Cost as a Function of Raw Material Costs 84
41 Operating Cost as a Function of % PB in Agglomerate 85
42 Operating Cost as a Function of Labor Force 86
43 Operating Cost as a Function of Dewatering Costs 88
IX
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TABLES
Page
1 Waterways Wastes 8
2 Atomic Absorption Parameters 39
3 PPM Cation Concentrations in the Distilled Water 41
Leaching Solution
4 PPM Cation Concentrations in the Simultated Ocean 42
Leaching Solution
5 PPM Cation Concentrations in the NH.OH Leaching Solution 43
6 PPM Cation Concentrations in the NaOH Leaching Solution 44
7 PPM Cation Concentrations in the Ammonium Sulfide Leaching 45
Solution
8 PPM Cation Concentrations in the Citric Acid Leaching 46
Solution
9 PPM Cation Concentrations in the HC1 Leaching Solution 47
10 PPM Cation Concentrations in the 10% Dioxane Leaching Solution 48
11 pH Values of Leaching Solutions 49
12 PPM Arsenic and Sodium Concentrations in Distilled Water 51
and HC1 Leaching Solutions
13 Mechanical Testing Program for Hazardous Waste Encapsulation 55
Program
14 Mass Balance 70
15 Installed Equipment Cost 72
16 Computer Program Listing 75
17 Sample Computers Economics Simulation 78
18 Operating Costs - $10007Year 79
19 Industries Currently Under Study 94
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TABLES (CONTINUED)
Page
20 Summary of Land Destined Hazardous Wastes From Inorganic 95
Chemical Industry
21 Annual Heavy Metal Wastes Generated by the Pharmaceutical 96
Industry
22 Estimated Total National Wastes from Electroplating and Metal 99
Finishing Job Shops, Metric Tons Per Year
xi
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ACKNOHLEDGMENTS
The authors wish to express their indebtedness to Mr. C. Wiles, the
Environmental Protection Agency's Program Monitor, for his constant
cooperation and valuable comments, and for his guidance of this work to
providing a viable response to problems in passivation of hazardous wastes
difficult to manage by current means.
The authors wish to acknowledge the valuable contribution of
Dr. R. Ottinger in indentifying problem areas in waste management re-
quiring new technological approaches.
The authors wish to acknowledge their indebtedness to Drs. E.
Koutsoukos and J. Blumenthal of TRW for their valuable inputs to the report.
Special thanks are due to Mr. R. S. Thorpe for work in the experi-
mental portion of this project.
Also to Mr. D. B. Kilday for work in the area of analytical determina-^
tions.
And to Mrs. V. R. Butler for the stenographical preparation of this
document.
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CONCLUSIONS
This work concerning organic, polymeric cementation and encapsulation
of hazardous wastes (TRW process) led to the following conclusions:
t Cementation of particulated solid waste containing heavy
metal contaminants such as Cu, Cr, Zn, Ni, Cd, Hg, and As,
and other metals such as Na, Ca and Fe can be readily
carried out with polybutadiene resin yielding agglomerates
having 94 to 97% by weight waste.
t Agglomerates can be securely encapsulated with 1/4 inch
thick polyethylene jackets by fusing powdered polyethylene
onto agglomerate surfaces, yielding passivated hazardous
waste.
Passivated hazardous waste, experimental products prepared
in the laboratory by the TRW process exhibit excellent re-
tention of hazardous contaminants in leaching by a broad
spectrum of aqueous solutions.
Products show high compressive strengths and withstand
freeze-thaw and mechanical impact.
A cost effective, high performance product would be
characterized as follows: dimensions, cubic, approximately
two feet on edge; weight, in the range 800 to 1000 pounds;
jacket, about 1/4 inch thick polyethylene resin; encapsu-
lated hazardous waste agglomerate cemented by 3 to 6% by
weight polybutadiene resin, and jacketed by about 4% w/w
polyethylene resin. Total resin required is about 8% w/w.
Passivation costs are estimated to be about $91 per ton in
a processing operation yielding 20,000 tons per year.*
1C
Costs are based upon price of virgin resins vended by resin producers.
XUT
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Resin costs account for more than 50% of the product
production costs.
t Difficult to manage wastes designated for disposal in
landfill, deep well, etc., were assessed to be amen-
able to successful localization by the TRW process,
such wastes containing, for examples, sodium
metaarsenate and arsenic trisulfide.
High performance localization of waste may be maintained
by TRW process products under ambient conditions more
varied and severe than those which define the limits of
stability of wastes passivated by current means employing
resins or waste "fixation" additives.
The TRW process exhibits general applicability in passi-
vation of dry particulated waste, i.e., no prior treatment
of waste nor adjustment of the process is required.
xiv
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RECOMMENDATIONS
Fabrication of commercial application scale prototypes is required in
order to carry out chemical and mechanical characterization of cost ef-
fective products. This information is necessary for correlating performance
of laboratory test specimens with that of full-scale products. Thus a
more complete and accurate picture is provided for product performance
under service conditions.
The agglomerated test specimens fabricated in this study from resin
coated, particulated contaminants were "hardened" thermally throughout so
that equivalent products would be realized for comparative evaluation
purposes. The need for such thorough hardening is questionable, in our
opinion, for realization of high performance of encapsulated waste. Yet
production costs were based upon such a procedure because it was desirable
to base the costs upon application scale products which approximate the
test samples fabricated and characterized in the study. By producing
products having a partially cured agglomerate where the surface and the
region immediately below is characterized by particulates fused hard and
the interior by material exhibiting a rubbery consistency rather than
products having an agglomerate that is thoroughly hardened, it would be
possible to markedly advance the rate of production of products. It also
may be possible to eliminate certain items of capital equipment.
Within the framework of the above considerations, additional appli-
cation scale prototypes are required for chemical and mechanical character-
ization. With such information in hand, the product fabrication procedure
should be restructured in order to minimize production costs consistent
with high product performance.
Finally, prototypes should be fabricated with impure and scrap resins.
For the sake of convenience and the constraints of the study, virgin,
commercial resins were utilized. In our opinion, an impure cementing resin
would be very satisfactory in formation of agglomerates. Although the
quality of resin employed for encapsulating the agglomerate should not be
xv
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compromised significantly, the cost of this material may be reduced by use
of resin fillers and extenders. Fortunately, room for greater latitude
in resin quality lie in the higher cost cementing resin. Thus significant
impact upon product production costs could be realized by employing lower
cost resins yet maintain high product performance.
In summation, advancement of this work requires:
t Evaluation of full-scale prototypes.
Investigation of prototypes with agglomerates surface
hardened to various depths.
0 Examination of the utility of products fabricated
. with impure and scrap resins.
xvi
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1. INTRODUCTION
Under Section 212 of the Resource Recovery Act of 1970, the Environ-
mental Protection Agency was charged with the preparation of a Report to
Congress defining and describing various aspects of hazardous waste
management. Of particular concern are those wastes which possess the
potential of harm to man and/or the environment. The hazardous wastes
may be either in the solid state or mixed with a liquid, most often water,
in the form of sludges, slurries or slimes. Almost any branch of modern
industry, metallurgical, chemical, ceramic, mineral, f&od processing,
metal treatment, petroleum refining, treatment of municipal sewage, etc.,
leaves behind some kind of wastes; described varyingly as tailings, scraps,
rubble, garbage, refuse, residue, sludge, slime, slurry, mud, etc. These
wastes often contain toxic compounds including arsenic, lead, mercury,
selenium, beryllium, cadminum, zinc, and chromium. The potential hazard
is increasing rapidly due to the greater quantities of concentrated toxic
solids and sludges being produced by policies and equipment designed to
limit air and water pollution.
The Report to Congress was based upon specific contract efforts de-
signed and programmed to provide information and insight necessary to the
presentation of a complete and accurate picture. The first contract effort,
initiated in July 1971, identified a number of hazardous materials, their
sources and quantities, and the technology utilized for their treatment.
The second contract effort, initiated by TRW in December 1971, had three
concurrent objectives: (1) refine the listing of hazardous wastes based on
further information, (2) analyze and assess current hazardous waste disposal
technology, and (3) define research and development necessary to provide
information or adequate technology. This effort culminated in a final
report delivered in February 1973.
The TRW work indicated that among the areas of application used in
waste elimination, Figure 1, the one pertaining to elimination of non-
destructible wastes (localization) in particular required extra emphasis
in additional development. Certain wastes contain hazardous, heavy metals,
1
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WASTE ELIMINATION SCHEDULE
HAZARDOUS WASTE
RECYCLABLE
NON-RECYCLABLE
DIRECT DISPOSAL
LOCALIZATION
LANDFILL
. DEEP WELL DISPOSAL
, OCEAN DISPOSAL
DETOXIFICATION
CONTAINERS
MATERIAL MATRICES
TRW PROCESS
(HYBRID CONTAINER-
MATRIX SYSTEM)
INCINERATION
BIOLOGICAL
DEGRADATION
CHEMICAL
ALTERATION
-ELECTRO-MAGNETIC
WAVE
MODIFICATION
Figure 1. Areas of Application
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e.g., arsenic, lead, mercury, selenium, beryllium, cadmium, zinc, and
chromium, others contain fluorides, bromides and iodides, which can be
controlled only by localizing the materials, or isolating and then local-
izing the contaminants. Present containerization and matrix incorporation
methods that were employed did not assure high performance localization.
Successful localization signifies that the probable release of toxic
materials from localized waste solids and sludges is at a level consistent
with both short-term and long-term environmental protection.
In July of 1973, the scope of the TRW study was expanded to include
initial bench-scale process development efforts with the objective of de-
monstrating the feasibility of a new toxic waste localization process
(TRW process, Hybrid Container - Matrix System).* In the process, dry
wastes are agglomerated by cements which yield stiff, strong composites
with very high waste contents. Subsequently, the agglomerates are en-
capsulated by jackets of selected materials. These jackets are designed
to adhere to the surface of the agglomerate and to exhibit mechanical
advantages as well as the desired chemical ones.
Wastes localized in this fashion were Assessed to consume minimal
amounts of "fixing" material and yet withstand more effectively than
current localization methods the mechanical and chemical stresses of
various disposal schemes, such as landfill, deep well disposal, and ocean
disposal or alternative management for sufficient periods of time to en-
sure safety and protection. Thus, wastes localized by the TRW process
were expected to exhibit load bearing properties in advance of those
characterized by containers with non-agglomerated contents. The products
of the new process, however, retain the singular advantage of containers
by providing a distinct material discontinuity at the interface of the
waste and the environmental stresses. In the non-containerization method,
localization of wastes into material matrices, such as blending wastes
into molten resins followed by solidification of the melt, leaves unpro-
tected wastes at the interface subject to delocalization by water leaching
and other dispersion forces. As increasing concentration of wastes are
localized in material matrices in order to conserve the amount of
"fixing" material employed, performance properties are compromised due to
increasing concentration of waste exposed to environmental stresses. With
*
See Section 3.1 for detailed description of concept of TRW process.
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delocalization of surface exposed waste, more waste is exposed due to the
resulting increased surface area; delocalization then proceeds into the
body of the product.
»
The initial phase of the TRW process development program under
Contract No. 68-03-0089 to the Solid and Hazardous Waste Research Labora-
tory of the National Environmental Research Center, Cincinnati, Ohio, was
designed to determine information on three important process character-
istics: (1) the technical behavior of agglomeration and encapsulation;
(2) the ability of the method to passivate hazardous wastes; and (3) the
process economics. In this program waste simulants were used to ease the
handling problems and to insure a known baselipe for the processing and
environmental tests. A number of different organic and inorganic cements
and jacketing substances were investigated in various proportions in order
to identify suitable materials. The effectiveness of waste localization
was determined on the basis of leach tests using various solutions in
which passivated waste blocks were immersed. A preliminary design and
economic analysis was determined for both the organic and inorganic
cementation processes based on the process data developed in the laboratory.
This effort culminated in a final report delivered in November 1974.
Organic cements were favored over inorganic ones, such as Portland
Cement and Piaster of Paris, because they were found to cure more rapidly
and to "fix" higher concentrations of waste. Details concerning organic
cementation is given in Appendix A. A feature of this work was the
identification of a resin binder system which agglomerated high concentra-
tion of hazardous waste, and two resins that readily encapsulated the
agglomerates with tough, high performance jackets. The binder system was
based upon carboxyl terminated oligomers of 1,2 polybutadiene and epoxide
chain extenders. It was found to stabilize dry, particulated waste in
concentrations as great as 96 to 97% by weight. The resulting aggregates
of waste were dimensionally stable and strong in compression. They were
readily encapsulated by 1/4 inch jackets employing polyvinyl chloride
plastisols and powdered polyethylene. These jacketing resins, particularly
the latter, are mechanically tough and chemically stable, and were found
to undergo upon processing minimal penetration into the agglomerate. This
4
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made the jackets more effective as barriers by allowing the bulk of the
resins, about 1/4 inch thick, to concentrate upon the surface, yet there
was sufficient penetration to provide desirable mechanical locking of the
jacket to the substrate. The above and other features, such as the
realization of high performance products, coupled with the ease of the
processing, indicated that the TRW process was a cost effective means for
hazardous waste localization.
This report provides the results of additional study for the Solid
and Hazardous Waste Research Laboratory on the localization of
wastes containing heavy metals by employing organic resins for formation
of heavy metal waste agglomerates and for jacketing the agglomerates.
Based upon the results of the previous study, cost effective, high per-
formance resins selected for employment on this work were polybutadiene
for agglomerate formation and high density polyethylene for jacketing the
agglomerates. The three major objectives of this work were: (1) to show
general applicability of the above resins in the TRW process to passi-
vation of dry, heavy metal wastes notwithstanding their chemical compositions
and material consistencies, and provide an encapsulation method suitable
for large scale operations, (2) to demonstrate the high performance
character of the products under exacting environmental stresses, and (3)
to provide initial process designs and cost estimates for localization
of wastes.
This report is set forth as follows: Section 2 provides the se-
lection, identification, and characterization of wastes for localization
by the TRW process, in Section 3, demonstration is provided with respect
to general applicability of the passivation process; the laboratory
method, developed and employed for localizing wastes, is given in detail.
Section 4 shows the results of Teaching localized waste products by a
broad and exacting series of aqueous leaching solutions. The mechanical
characterization of products is given in Section 5. Section 6 shows pro-
cess designs, the general process economics model, and the determined
costs for localizing wastes. In Section 7, industrial wastes are analyzed
with respect to localization by the TRW process. Section 8 gives gen-
eralizations of and potential modifications to the accomplished work.
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2. IDENTIFICATION, SELECTION, AND CHARACTERIZATION OF WASTE STREAMS
The major thrust of this portion of the work was to identify hazard-
ous, heavy metal containing wastes with broadly varying chemical compositions
and material consistencies for localization by the TRW process. Such wastes
were required in order to demonstrate viability of the premise that the TRW
process is applicable to dry wastes generally without need for tailoring
the process to the specific waste. (Waste types are discussed in Sections
7 and 8.) With this objective in view, the selection of waste was geared
to those constituting the largest output from industrial sources. The
selection criteria, however, were compromised in certain cases because some
wastes could not be made available for investigation within the time scope
of the program.
The characterization of wastes was limited mainly to information
offered by the suppliers. The chemical compositional makeup of some
wastes employed in preparing test specimens, however, were assayed; the
results are provided in Section 4, Leaching Tests.
2.1 WASTE IDENTIFICATION
Two types of wastes were sought for evaluation in the TRW process:
t One characterizing composition of heavy metal contaminants
issued by chemical industry and waste sequestering opera-r
tions.
Another characterizing composition soluble in water wherein
soluble salts are laced by small concentrations of heavy
metal.
The former can be viewed as product of heavy industry while the
latter stems from fine industry such as pesticide production. The latter
material will also test the performance of the TRW process in passivation
of contaminants such as salts of fluorides, cyanides and bromides.
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The U.S. Army Corps of Engineers, Vicksburg Experimental Station
supplied to this study ten waste sludges of the first type. The sources
of the wastes and the major contaminants in their contents are indicated
in Table 1.
Additional sludges were sought from other sources, but those received
(described below) were not used because they were similar to Waterways
electroplating and pigment production sludges.
Electroplating sludge, consisting of 5 gallons of a liquid con-
taining less than 1% solids, was obtained from Ajax Hardware in the City
of Industry, California. The major contaminants were zinc, copper and
cyanide. U.S. totals of electroplating wastes produced each year includes
2 million pounds of copper and 21 million pounds of cyanide.* It is our
understanding that these wastes normally are disposed of through the sewer
systems.
Paint sludges were provided by Sinclair Paint Company of Los Angeles
in two forms, water-based and organic solvent. The major contaminants in
the water-based sludge sample, which stem from the production of enamels, were
chromium and mercury. The U.S. production total for this type of sludge is
26 million pounds per year.* The second sample received from Sinclair
Paints was solvent-based sludge from flat vinyl paint production. The
major contaminants were lead, chromium, cadmium and cyanide. The paint
industry produces 36 million pounds per year of this type of sludge.*
Both forms of sludge are usually disposed at sanitary landfills in 55
gallon drums.*
Concerning the latter type waste, monosodium methanearsonate con-
taining waste was obtained from operations of the Ansul Chemical Company
in Marinette, Wisconsin. Other identified wastes contained cacodylic acid
and sodium cacodylate, but the monosodium methanearsonate waste was more
TRW Report #21485-6013-RU-OO prepared for the Environmental Protection
Agency, Recommended Methods for Reduciton, Neutralization, Recovery or
Disposal of Hazardous Wastes, Volume XIV.
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TABLE 1. WATERWAYS WASTES
Code No. Source Major Contaminants
TOO SO scrubber sludge, lime process, eastern Ca, SO/"/SO,~
coal
200 Electroplating sludge Cu, Cr, Zn
300 Nickel - Cadmium battery production sludge Ni, Cd
400 SOX scrubber sludge, limestone process Cu, S04~/S03~
eastern coal
09 500 SOX scrubber sludge, double alkali process, Na, Ca, S04~/S03~
eastern coal
600 SO scrubber sludge, limestone process, Ca, S0.~/S03~
western coal
700 Pigment production sludge Cr, Fe, CN
800 Chlorine production brine sludge Na, Cl", Hg
900 Calcium fluoride sludge Ca, F~
1000 SOX scrubber sludge, double alkali process, Cu, Na, S04~/S03~
western coal
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prevalent. Since the above compounds come from one industry, pesticide
manufacturing, it was decided to sample the waste produced in larger
quantities. The waste sample contained 1-1/2% by weight monosodium
methanearsonate, 49% sodium chloride and 49% sodium sulfate. Such arsenic
containing wastes are presently stored on-site at Ansul in concrete vaults.
Arsenic trioxide containing waste is recovered in large amounts from
the flue dust of metal smelting operations. Many smelters send this waste
to American Smelting & Refining Company (ASARCO) in Tacoma, Washington.
After recovering metals of value, ASARCO has been storing the arsenic tri-
oxide. Presently, the compound is recycled to industry. Since ASARCO ships
only in carload lots, it was not practical to obtain this material in sample
quanities.
2.2 SELECTION
The wastes selected for agglomeration study, Section 3.2, were those
designated in Table 1 as 200, 300, 500, 700, and 900. These materials
differ significantly in chemical composition and material consistency.
Furthermore, they stem from a broad spectrum of sources in the chemical
industry, each source issuing significant quantities of waste. A blend of
equal parts by weight of 200, 300, 500, 700, 800, and 900 were employed in
encapsulation of wastes, Section 3.3, and for detailed leaching and mechanical
property studies, Sections 4 and 5. The blend contained the following atoms:
Cu, Cr, Zn, Ni, Cd, Na, Ca, Fe, Hg.
The waste with monosodium methanearsonate was also selected for en-
capsulation and study. The arsenic contaminant, existing as a sodium salt
in a mixture of sodium salt compounds, is expected to be very water soluble.
As such, specimens from this material for aqueous leaching studies would
provide an exacting test of the ability of the encapsulation method to
passivate such wastes. Passivated sodium chloride was also studied, there-
by gaining some insight of the ability of the TRW process to passivate
alkali metal cyanides, fluorides, and similar compounds.
-------
2.3 CHARACTERIZATION
Five gallon quantities of aqueous sludges 200, 300, 500, 700, 800 and
900 were dewatered to a consistency that exhibited no mobile water by ex-
posing the material to the atmosphere and sunlight. The resulting residues
were then heated in an oven at 300°F for about 1/2 hour. The residues
thereafter granulated readily with mechanical stirring. A uniform con-
sistency, i.e., absence of gross aggregates, was sought in particulation.
No attempt was made to obtain a particular particle grind because various
material consistencies were desired for agglomeration and encapsulation.
Demonstrating successful passivation would indicate that it is not necessary
to reduce wastes with different particulation characteristics to a specific
grind, nor is it necessary to reduce a given waste repeatedly to the same
grind. In some cases, mechanical stirring was not necessary, Residues of
sludges 500 and 900 did not require stirring to obtain uniform material
consistencies suitable for encapsulation.
The following two figures show the particulated residues of 200 and 700
under 100 times magnification.
The residues appeared as agglomerated fines. The average dimensions
of the agglomerates ranged between 5 to 15 mils. Sparkle exists in Figure
3 and it is not evident in Figure 2. This may be due to highly reflecting
surfaces; such ordered surfaces characterize crystal faces. It appears
that crystals of such magnitude may be absent in sludge 200 residue.
With respect to the monosodium methanearsonate containing waste, it
was grey-white in color and exhibited the consistency of sugar. As a sodium
chloride source for this work, table salt was employed.
10
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Figure 2. Waste 200 Residue (Electroplating Sludge)
Magnification 100X, Scale Division 0.5 Mil
Figure 3. Waste 700 Residue (Pigment Production Sludge)
Magnification 100X, Scale Division 0.5 Mil
11
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3. APPLICATION OF LOCALIZATION PROCESS TO SELECTED WASTES STREAMS
The resins employed for localization of wastes described in Section
2.2 were modified polybutadiene and polyethylene. Their selection resulted
from earlier work under Contract No. 63-03-0089. The modified polybutadiene
resin for waste agglomeration was assessed to provide the following advan-
tages: blends readily with and contains large quantities of heavy metal
wastes; remains shelf stable; agglomerates wastes by fast chemical reaction
that is not sensitive to waste composition; yields tough agglomerates, aug-
ments dewetting from mold; provides chemical sites for desirable interaction
with jacketing resin; and fashions readily from butadiene, a commodity used
for making rubber for tires. The jacketing resin, high density polyethylene,
was expected to show the following advantages: excellent chemical stability,
nonbiogradable, tough and npnpermeable to metal ions and other waste
permeants, functional over a wide temperature range, low cost, and com-
mercially available in pulverized form allowing for ready envelopment of
agglomerated wastes with resin jackets.
The above resins in combination were assessed to yield high perfor-
mance, cost effective passivated waste products. This assessment could not
be applied distinctly to other resin systems, consequently, the polybutadiene-
polyethylene resin systems are unique, in our opinion, for fabricating pas-
sivated wastes by agglomeration and encapsulation. Included in the asess-
ment were product processing techniques. Technological barriers to ready
reproducible processing of encapsulated wastes are, in our opinion, markedly
reduced by the physical and chemical character of these resins.
Employing the above resins, the major thrust of this portion of the
work was to demonstrate and realize the following:
The general applicablity of the TRW process to local-
ization of dry, heavy metal wastes without need for
process modification.
12
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t A method for agglomerating and encapsulating wastes
that can be readily carried out and yields products
with seam free resin jackets adhering tenaciously
to the waste agglomerate.
0 A set of specimens for laboratory testing to demon-
strate the performance capabilities of the passivated
wastes.
3.1 PROCESS CONCEPT
Prior to providing in the following sections the experimental work of
this study, the process concept and the attendant advantages are outlined
here. The thrust of the experimental work is to provide proof that the
anticipated advantages are readily realizable.
In the TRW process, unconfined particulate waste is first agglomerated
and a container is then fabricated about it, thus yielding an encapsulated
product. Conventionally, particulate waste is entered into a container
and the waste is sealed by fixing a lid onto the receptacle. In effect
the TRW process is the reverse of the conventional process, and this gives
rise to a very significant benefit: in the event the product is subject
to an applied mechanical load, such as that stemming from overburden in a
landfill or from stacking products in transporting, that load is sustained
by the product contents rather than the product walls. Since the walls
need not be structured to be load bearing, an increased number of types of
material are thus made suitable for encapsulating waste. Most importantly,
it makes possible the use of softer materials such as plastics in the
fabrication of high performance products rather than hard, stiff metallic
ones. As a class, it is well recognized that plastics are more resistant
to chemical corrosion than metals. With cost considerations, plastics
have no metallic counterparts vis-a-vis chemical stability.
t
Another important advantage of the TRW process in contrast to con-
ventional containers concerns the nature of sealing the waste content.
Fixing a lid onto a receptacle in order to effect a proper seal usually
13
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involves the use of materials different than those employed in receptacle
and lid fabrication. These materials are usually gaskets, o-rings,
sealants etc. The use of dissimilar materials requires skill in their
utilization for effecting proper closure. Even then, containers are usually
observed to fail at the juncture of receptacle and lid. However in the
TRW process, a single material is employed for encapsulation of wastes and
the product is characterized by being seam free.
With anticipated performance advantages characterising an agglomerated
waste encapsulated seam free by plastic, it remains to select the specific
plastic; one that is low cost, readily processable, mechanically tough
and chemically resistant to both the chemical action of the agglomerate
and the disposal environment. Under Contract No. 68-03-0089 the preferred
resins were found to be polyvinyl chloride plastisols and powdered poly-
ehtylene. Since plasticizers are employed in the manufacture of the
plastisols, and these are potentially Teachable from the plastic, the
choice was narrowed to powdered polyethylene. Of particular importance
in the choice of this polyolefin was the commercial availability of its
powdered form from several large plastic producers. It is very desirable
to utilize the powder because it makes possible ready fabrication of thick
elements of plastic onto agglomerates without need for heavy duty equip-
ment by the novel means to be described later. With thick elements, one
gains mechanical advantages as well as the expected chemical ones. This
realization of thick coatings upon substrates is not readily attainable
through the art of coatings technology.
The desired product of the TRW process should consist of a tough,
chemically stable plastic jacket encapsulating an agglomerate of waste and
furthermore tenaciously adhering to its surface. A product with a properly
adhered plastic jacket is expected to exhibit greater resistance to
mechanical stresses than one not so characterized. In the former case,
the substrate reinforces the plastic, for examples, with respect to re-
sisting puncture, abrasion, and mechanical impact. Without this reinforce-
ment, the plastic per se must withstand the mechanical stress thus giving
rise to products of lessor performance.
14
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Up to this point, the advantages are presented concerning a product
characterized by a resinous jacket encapsulating and adhering to an ag-
glomerated waste. Attention must be given now to the nature of the
agglomerated waste in order to realize ease of processing and high
performance products. It is desirable for particulate waste to be treated
with resin for subsequent cementing without employing heavy duty equipment.
It is necessary for the treated material to be shelf stable. (Thus the
agglomerating steps can be carried out at ones convenience rather than in
adherence to a given time schedule, a constraint that arises in use of
shelf unstable material. Specified time intervals between process steps
i.e., resin coating the waste particulates followed by cementing them
together, limits the flexibility of the agglomerating operation.) It is
obviously advantageous to have agglomeration occur rapidly upon its
initiation. During the agglomeration, it is important for the waste
particulates not to settle out but remain homogeneously dispersed in the
agglomerate in order to realize optimal mechanical properties. And to
reduce cost, the resin employed for waste particulate agglomeration must
be capable of stabilizing a high content of waste.
The resin system selected for cementing waste particulates into
agglomerates was based upon 1,2-polybutadiene. This material is readily
prepared in polar organic solvents by elemental sodium polymerization of
butadiene, a well known material in making of synthetic rubber. Sodium
not only causes butadiene polymerization, but in addition allows the
positioning of chemically functional groups at the terminal ends of the
polybutadiene chain. (The nature and role of the functional groups will
be discussed later.) It is pointed out here that the 1,2 configuration
is considered to be important for the purposes of this study mainly because
it is inherently stabile in air. Other configurations of polybutadiene such
as 1,4 cis and trans do not exhibit this advantage. The later materials
unstabilized, will oxidize readily when exposed to air. In commercial
practice the cis configuration, which is very important in truck tire
manufacture, is stabilized with antioxidants. Such stabilization is not
suitable when polybutadiene is geared for use as a cement for rapidly
fabricating a stiff product because the high degree of chemical condensation
15
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required quickly would not be readily realizable when it is carried out in
the presence of antioxidants. Antioxidants interfer with the condensation
reaction. Thus the stability in air of 1,2 not only yields shelf stable
resin coated waste particulates but also ones that chemically condense
readily.
The chemical condensation of 1,2 occurs with peroxide initiation. The
required peroxides are well known in rubber vulcanization technology and
are commonly employed and commercially available. The use of the peroxides,
however, requires an elevated temperature (about 320°F) in order to initiate
chemical condensation. Unfortunately, upon heating a mixture of particulates
with 1,2-polybutadiene resin, the resin becomes fluid and the particulates
then tend to settle out. In order to preclude such an event the functional
groups of the polymer is invoked.
The functional groups are geared to react with a chain extender that
is added to the cement formulation of resin and peroxide at temperatures
lower than 320°F. This reaction increases the viscosity of the resin
mixture thus counteracting the thermally induced fluidity. Under these
circumstances, the particulates are expected to remain fixed and homoge-
neously dispersed in the resulting agglomerate. Such properties, and the
nonpolar nature of 1,2-polybutadiene, allow incorporation of high concen-
trations of waste into the resin cement with minimal sacrifice of performance.
The technical advantages given above, shelf stability, fast reactivity,
high solid content, coupled with the desirable ready demolding character of
polybutadiene products and low cost cannot, in our opinion, be duplicated
in any other organic cement.
The preferred functional groups are carboxyl ones. These are readily
fixed to 1,2-polybutadiene by blowing carbon dioxide into reaction vessel after
the sodium induced polymerization of butadiene has taken place followed by
acid neutralization. The resin is isolated if desired upon vaporization of
the solvent. (Although the isolated resin was used in this work because
it was available in this form from the vendor, use of the isolated resin is
not required, nor indeed desirable from a cost viewpoint. In practice, the
16
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polymerization solution is expected to be treated with peroxide and chain
extenders and then employed as such to wet hazardous waste particulates.
The solvent will exhibit the property of being readily vaporizable, it will
be condensed and then reemployed for additional polymerization.) The pre-
ferred chain extenders are epoxides, particularly the well known and most
commonly employed one, the diglycidyl ether of bis phenol A.
It is pointed out here that all the materials except for the 1,2 polymer
employed in the stabilization of hazardous waste stem from large scale
commercial operations. Indeed it is the objective of this study to employ
only prevalent low cost materials. The 1,2-polybutadiene polymer with
terminal carboxyl groups is not available generally in the U.S., the
material is made commercially at the present time in Japan, but the art is
well known and the preparation easily carried out. The major expense in
preparing commercial 1,2-polybutadiene lies in purification of the material,
that generally involves freeing the material from the products of acid
neutralization, which is required because it is geared for electrical and
coatings use. For the purpose of cementing waste such a pure material is
not necessary (although employed here because it was available) and a crude
polymer, in our opinion, will serve equally well.
The TRW process, although employing well known materials, employes
them in unique combination. This combination is geared to yield products
having high performance yet requiring minimal amounts of material in their
fabrication. (The materials per se are of the lowest cost consistent with
realization of high performance.) It is estimated that total resin re-
quired will be about 7 to 8% w/w with 3 to 4% employed in cementing about
4% employed in encapsulating the resulting agglomerates.
The fabrication of products is readily carried out. Particularly
advantageous, no heavy duty equipment is required. The process is geared
to be carried out by unskilled workmen and it does not require adherence
to a strict routine.
17
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3.2 GENERAL APPLICABILITY
Residues of dewatered Wasterway sludges 200, 300, 500, 700, and 900,
isolated as described in Section 2.3, were selected for demonstrating gen-
eral applicability of the waste passivation process. They were coated by
an acetone solution of modified polybutadiene. The solution was combined
with about 160 grams of residue and mechanically stirred in a two gallon
Hobart mixer. This blending operation required five minutes. After blend-
ing, a constant weight material was obtained in about two hours by leaving
the material exposed to the atmosphere. The resin content of the grind
was about 4% by weight.
Prior to agglomerating the resin coated particulated wastes, it was
considered important to observe the free flowing character of the particu-
lates and their shelf stability. Free flowing particulates facilitate
loading of large molds for subsequent thermal fusion of particulates into
large agglomerates.* The property of shelf stability places essentially
no time constraints upon initiating fusion operations. These advantages
contribute to ease of making passivated products. The product performance
is consequently less sensitive to the mechanics of product fabrication.
Agglomeration of the particulates was carried out under moderate mechan-
ical pressures in the temperature range of 250 to 400°F and at various
time intervals after the resin coating operation. The details of agglom-
eration and encapsulation are provided in Section 3.3. Here demonstrations
were sought which showed different wastes readily agglomerating over a wide
temperature range from free flowing resin coated waste particulates stored
at various time intervals.
Determination of size of cost effective, passivated wastes is given in
Section 6.1.1, Determination of Dimensional Nature of Products.
18
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The following figures show samples of resin coated wastes 200, 300, 500,
700, and 900 as free flowing particulates and fused agglomerates. The coated
particulates flowed readily through the stem of a glass funnel, Figures 4,
6, 8, and 10. No residue was noticed on the funnels after flowing the sam-
ples. Figure 12 exhibits the discrete nature of the particulates. In the
above operations, and after storing in containers, the particulates remained
discrete and free flowing.
The agglomerated particulates, Figures 5, 7, 9, 11 and 13, yielded hard,
tough specimens, some exhibiting a glossy finish. Agglomeration was carried
out on resin coated particulates after time intervals of five minutes to
thirty days. All the specimens showed hardness values greater than Shore
A 100.
This work verified the premise that highly loaded agglomerates can be
fashioned from different wastes over a wide temperature range, and that
resin coated wastes can exist as free flowing particulates which exhibit
shelf stable properties.
3.3 METHOD OF WASTE AGGLOMERATING AND ENCAPSULATING
The purpose of this element of work was: (1) to establish an agglom-
eration and encapsulation method that could form a basis for large scale
production of agglomerated wastes weighing 500 to 1500 pounds with one-
fourth inch thick resin jackets,* and (2) to fabricate specimens to demon-
strate the performance capabilities of the passivated wastes. The specimens
for testing were fabricated as cubes 3 inches on edge, characterized by a
Rationale for size of passivated waste products is given in Section
6.1.1, Determination of the Dimensional Nature of Products.
19
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Figure 4. Polybutadiene Coated Residue of Sludge 200
Figure 5. Fused Residue of Sludge 200
20
-------
Figure 6. Polybutadiene Coated Residue of Sludge 300
Figure 7. Residue of Sludge 300 Fused at 310°F
21
-------
Figure 8. Polybutadiene Coated Residue of Sludge 500
Figure 9. Fused Residue of Sludge 500
22
-------
Figure 10. Polybutadiene Coated Residue of Sludge 700
ft.
Figure 11. Fused Residue of Sludge 700
23
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1
"*
I 7
Figure 12. Polybutadiene Coated Residue of Sludge 900
Figure 13. Fused Residue of Sludge 900
24
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1/4 inch thick resin jacket adhering to a cubic agglomerate of waste, 2-1/2
inches on edge. The densities of the agglomerate wastes depended upon the
nature of the materials. Agglomerated particulates of residues of 200 and
300 with 4% by weight binder were determined to be 98 lb/ft3 and 110 lb/ft3.
3
A working value of 100 lb/ft was employed for estimating dimensions of
large passivated waste products.
The passivated waste products must be characterized by seam-free, en-
capsulating resin jackets, and by tenacious adhesion of jacket to agglom-
erate in order to realize high performance products. Seam-free jackets were
readily fabricated according to the method given below. Tenacious adhesion
of jacket to agglomerate occurred in all cases due to an incremental pene-
tration of the jacketing resin into the agglomerate, which formed a mechanical
lock between jacket and agglomerate. Although chemical adhesion between
jacket and agglomerate binder was also expected to occur due to the chemical
nature of the adherends, it was not possible to assess the respective contri-
butions of the mechanical lock and the chemical bond to the strength of the
adhesive bond.
The method of agglomeration and encapsulation, utilizing the blend of
sludge residues described in Section 2.2, is provided here in a pictorial
sequence. The encapsulated products are shown in cross section.
3.3.1 Procedure for Passivation of Wastes
Figure 14 shows the agglomerated waste blend emerging after molding.
The agglomerate slipped readily from the mold even though it contained high
solid loadings, i.e., about 95% by weight wastes. Facile mold release can
be attributed to the non-polar chemical nature of polybutadiene and to
agglomerate contraction from shrinkage of the material while undergoing a
thermosetting reaction and subsequent cooling. In some cases, however,
slippage did not occur readily. Further exploratory work showed that 0.1%
by weight powdered polyethylene incorporated into the agglomerate would
enhance slippage in all cases. With respect to molding 500 to 1500 pound
agglomerates, the agglomerates would be removed by slipping the mold up-
ward as described in Section 6 rather than by extracting the agglomerate
from the mold as shown in Figure 14.
25
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.
Figure 14. Agglomerated Hazardous Waste
Residue Emerging from Mold
In Figure 15 the agglomerate is shown positioned for resin jacketing;
Figure 16 shows the agglomerate submerged in powdered polyethylene.
Figures 17 and 18 show the five-sided resin jacketed agglomerate after
being removed from its mold upon completion of thermal fusion of the powder-
ed resin at 350°F followed by solidification of the melt.
An indented configuration was selected in the design of the mold be-
cause it secured the agglomerate during the five-sided jacketing step. The
figures show a "step" in the jacket at the "lips". In addition, when the
final jacketing step was carried out, the step of solidified polyethylene
contributed to faster penetration of heat at the lips than at other points.
Thus, the added powdered polyethylene at the lips melted first thereby
allowing displacement of entrapped air upward and through the non-fused
material. By this method, seam-free fusion was readily carried out.
26
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Figure 15. Hazardous Waste Agglomerate Positioned
for Resin Jacketing
Figure 16. Agglomerate Submerged in Powdered Polyethylene
27
-------
r
Figure 17. Non-Jacketed Side Seen on the Free-Standing
Agglomerate After the First Jacketing Step
Figure 18. Five-Side Jacketed Agglomerate
Resting on Mold Pedestal
28
-------
Particular attention was given in this work element to understanding
the process for introducing the resin for agglomerate jacketing. In the
laboratory operation, the powdered resin was hand packed into the cavity;
this procedure would be cumbersome and possibly costly in a production
operation. With respect to jacketing 500 to 1500 pound blocks of agglom-
erate, a powdered resin would be sucked into the area between the mold and
the agglomerate with a vacuum system. The resin would then be fused onto
the agglomerate by heating through the mold. As presently visualized, a
port would be provided at the bottom of the mold shown in Figure 15 and a
vacuum line would be attached. A cover plate with port for powdered resin
delivery from a flexible tube would be affixed and suction applied. The
suction port would be under the agglomerate; this would prevent entry of
powdered resin into the suction tube. Nevertheless, sufficient air chan-
nels are expected to exist to allow ready displacement of the air.
Figure 19 shows the free flowing nature of the powdered polyethylene
employed in jacketing agglomerates. This material, flowing gravimetrically
or pushed pneumatically, is expected to readily fill and intimately occupy
an air evacuated cavity.
Figure 19. Powdered Polyethylene Seen Free Flowing
Under Gravimetric Force
29
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Figure 20 shows the five-sided resin jacketed agglomerate positioned
for final resin jacketing. Powdered resin was applied and then fused onto
the non-jacketed side.
Figure 21 shows the encapsulated hazardous waste emerging from the
mold. Note the gap between encapsulated waste and mold walls. This was
due to shrinkage of molten resin upon cooling, and it contributed to easy
removal of the product.
Figure 22 shows a free-standing encapsulated waste.
Note the resin "flash" on the surface of the jacket about two-thirds
down from the top of the product. Since only the non-jacketed side (as
seen in Figure 20) was heated in the final jacketing step, some molten
resin flowed into the gap between the relatively cool five-side jacketed
agglomerate and the mold walls. During the final step, no appreciable
heating of the resin jacket of the five side jacketed portion of the
agglomerate occurred, and therefore it prevented expansion and possible
distortion of the product. This advantage was due to the poor heat con-
ducting property of the agglomerates. Were this fortuitous property not
present, and agglomerates good thermal conductors, it would not be readily
possible to localize sufficient thermal energy required for fusion of resin
in the final jacketing step onto the agglomerate without product distortion.
The resulting "flash", however, did not mitigate product performance.
Figure 23 shows a cross section of encapsulated hazardous waste.
Figure 24 provides a close-up view of the cross section.
Inspection of the cross section and interface provided no visual evi-
dence of seams in the resin jacket and showed intimate and tenacious adhesion
of the resin jacket onto the agglomerate.
3.3.2 Additional Waste Passivation Study
The agglomeration and encapsulation method was applied to the arsenic
containing waste described in Section 2.2 and to sodium chloride, the simu-
lated waste material employed in prior work under Contract No. 68-03-0089.
30
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Figure 20. Non-Jacketed Side of Agglomerate Seen
Positioned for Final Resin Jacketing
Figure 21. Encapsulated Hazardous Waste After Final
Resin Jacketing Step
31
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Figure 22. Encapsulated Agglomerate Seen
After Final Resin Jacketing Step
Figure 23. View of Cross Section of Encapsulated
Hazardous Waste
32
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Figure 24. Close-up View of Cross Section of Encapsulated
Hazardous Waste, a Blend Described in Section 2.2
The sodium chloride, as well as the arsenic containing waste, was used to
evaluate the passivation method with respect to retaining contents of en-
capsulants characterized by highly water soluble salts.
With respect to both of the above materials, agglomeration and en-
capsulation were readily carried out. The nature of the passivated pro-
ducts is given in Figures 25, 26, and 27. Visual inspection of cross
sections of encapsulated agglomerates of very water soluble materials pro-
vided no evidence of seams in the jacket. An interface area between
agglomerate and jacket can be observed, this phenomenum resulting from
partial penetration of jacketing resin into the agglomerate.
3.4 SPECIMENS PREPARED FOR TESTING
Employing the method described above, 32, 3 inch cubical encapsulates,
containing the waste blend described in Section 2.2, were prepared for the
testing regimes of the following two sections. The encapsulates were charac-
terized by 1/4 inch resin jackets encasing cube shaped agglomerates 2-1/2
inches on edge, with contents of 96% by weight heavy metal wastes. Of the
same character, two encapsulates from the arsenic containing waste given in
Section 2.2, and two encapsulates of sodium chloride were also prepared.
33
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Figure 25. Cross View of Encapsulated Arsenic
Containing Waste
Figure 26. Polyethylene Jacketed Agglomerates of
Sodium Chloride in Cross Section
34
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I
I
2l '3l 4\
Figure 27. Polyethylene Jacketed Agglomerates of Sodium Chloride
in Cross Section (Nearer View)
35
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4. LEACHING TESTS
The purpose of leaching tests was to demonstrate high performance capa-
bility of TRW encapsulated heavy metal wastes to withstand delocalization by
ambient aqueous solutions stemming either from the ecological environment or
industrial operations. Consequentially, a broad spectrum of aqueous solu-
tions was employed for fashioning leaching baths, thereby encompassing solu-
tions of exacting acidic and basic strengths, a simulant for ocean water, and one
containing organic matter. Into these baths 3" x 3" x 3" blocks of encap-
sulated wastes, prepared as described in Section 3, were submerged and
samples of bath solutions were withdrawn periodically for chemical analysis.
This work, described in detail below, indicated that encapsulation provided
high performance localization of heavy metals during leaching by exacting
aqueous solutions.
4.1 LEACHING PROCEDURE FOR COMPOSITE HEAVY METAL WASTES
The composite heavy metal waste described in Section 2.2, i.e., the
combined residues of sludges designated by Vicksburg Experimental Station
(Waterways sludges 200, 300, 500, 700, 800, and 900 from Table 1), were
agglomerated and encapsulated. Sixteen blocks of encapsulated waste were
employed. The blocks were placed in 2 liter beakers and submerged in dupli-
cate in aqueous solutions. Figure 28 shows the encapsulated wastes under
leaching conditions.
4.1.1 Trace Metals Assay Methods
The experimental procedure, analytical method, instrumentation and
parameters used to determine the concentrations of the metal ions in the
leaching baths are described as follows. The calibration graphs are given
in Appendix B.
i
<
4.1.1.1 Technique
Environmental leaching studies were begun with the exposure of sixteen
blocks to eight aqueous solutions: distilled water, 10% ammonium sulfide,
36
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Figure 28. Close View of Encapsulated Wastes under
Aqueous Solutions
1.5 N HC1, 0.1 N citric acid, 1.25 N NaOH, 0.1 N NH4OH, a simulated ocean
solution, and 10% dioxane. All the leaching beakers, sampling glassware,
and sample storage bottles were cleaned to prevent contamination from their
use. They had a thorough wash with Alconox and were rinsed thoroughly with
tap water. The glass beakers were washed with 3:1 HC1-HN03 (Aqua Regia),
the glass volumetric flasks with concentrated FLSO, warmed to 60°C and the
plastic sample storage bottles with HC103 (20%) solution. The glassware
was then rinsed thoroughly with distilled water. The sixteen blocks of
encapsulated wastes were washed with distilled water and a brush to remove
any surface contaminants.
Four liters of each solution were prepared using quantitative tech-
niques. The initial pH and concentrations of the cations (Cu, Cr, Zn, Ni,
Cd, Na, Ca and Hg) were determined for each solution. The blocks were then
separated into two groups to provide duplicate determinations at alternate
37
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data points. The encapsulated wastes were each immersed in 1200 ml of
leaching solution. The solutions were sampled after 1, 2, 5, 10, 20, 30,
45, 60, 90 and 120 days. The remaining solutions were used to prepare
calibration curves (see Appendix Figures B-l through B-8) and to maintain
the volume of the leaching solutions to a level of total encapsulated
waste immersion.
4.1.1.2 Testing Method
The Jarre!1-Ash 810 Atomic Absorption Spectrophotometer was used for
the determination of the concentration of all the cations with the ex-
ception of mercury. The mercury concentrations were determined using a
LDC UV Monitor, Model 1205, and a stannous chloride reduction procedure.
At each time interval (1, 2, 5, 10, 20, 30, 45, 60, 90 and 120 days)
100 ml samples were drawn from the leaching beakers. The concentration ef-
fects involved with withdrawing samples were considered when calculating the
concentration of the cations over the sampling period. When the volume of
solution reached 700 ml, the blocks were still totally immersed; 100 ml of
new solution was then added after each sample withdrawal, and the dilution
effects were accounted in the concentration calculations.
The pH of the samples for atomic absorption analysis was adjusted to
2, wherever necessary, with nitric acid; the samples were analyzed using
the parameters listed in Table 2. Four data points were determined for
each element. Calibration curves, given in the Appendix, were established
for each element in each solution.
The mercury content was determined by a cold vapor trap method. The
mercury in the sample is reduced to the elemental state using a 10% stannous
chloride solution and aerated from the system into the UV cell. The mercury
vapor absorbs the UV (254 NM) according to its concentration in the fixed
cell path. Absorbance (peak height) is measured as a function of mercury
concentration and recorded in the usual manner. The mercury calibration
curves(Appendix, Figure A8) were established for all the solutions with the
exception of the 10% ammonium sulfide. In order to liberate the mercury
38
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TABLE 2. ATOMIC ABSORPTION PARAMETERS
Element
Cu
Cr
Zn
Ni
Cd
Na
Ca
Hg
Slit (nm)
Width
1.0
0.2
1.0
0.2
0.4
0.4
1.0
UV Monitor
Analytical
Wavelength (nm)
324.7
357.9
213.9
323.0
228.8
589.0
422.7
254.0
Background
Wavelength (nm)
323.4
351.9
210.0
231.6
226.5
-
-
Gas
Mixture
Air acetylene
NpO acetylene
Air acetylene
Air acetylene
Air acetylene
Air acetylene
N20 acetylene
Detection Limit-ppm
in Aqueous Medium
.003
.005
.003
.01
.003
.01
.005
.0003
co
-------
with this solution a special procedure would have to be established. Dif-
ficulty was also encountered with the simulated ocean solution and a pre-
treatment procedure was established. The procedure treats the solutions
with the following oxidizing agents: 2 ml of 5% KMn04 and 2 ml of 5%
KpSpCL. It was also necessary to use a 20% stannous chloride solution.
The sodium content was not determined in the NaOH, NH^OH, ocean and
ammonium sulfide solutions. The calcium content was not determined in the
ocean and ammonium sulfide solutions.
4.1.2 Compilation of Test Results
Tables 3 through 10 present heavy metal analytical determination of
the selected leaching solutions in contact with duplicate samples of
encapsulated waste over a period of 120 days. One set of determinations
on each table shows heavy metal concentration of leaching solutions in
contact with dry, untreated waste (unencapsulated waste). Although the con-
centrations of eight metals were sought, Cu, Cr, Zn, Ni, Cd, Na, Ca, Hg,
some determinations were not possible due to interferences of substances in
some of the leaching solutions.
4.1.3 Explanation of Leaching Tables
The tables give the mean cation concentrations in ppm and the stan-
dard deviation of the four readings that were conducted at each data point.
These concentration values have been calculated from the calibration data
generated for each leaching solution. The concentrations listed under the
heading "Blank" give apparent values for the cations in the leaching
solution before the immersion of the blocks. The values reported under
"Unencapsulated Waste" are the cation concentration levels obtained by a 400
gram waste sample (approximately equal to the quantity of waste encapsulated)
in 12uO ml of the particular leaching solution. The comparative data will
dec..y demonstrate the effectiveness of the encapsulation in preventing
the solutions from solubilizing the waste materials. Table 11 reports the
pH values of the solutions over the sampling time period.
40
-------
TABLE 3. PPM CATION CONCENTRATIONS IN THE DISTILLED WATER LEACHING SOLUTION
Cations
Cu
Cr
Zn
Ni
Cd
Na
Ca
Hg
Blank
.0025+. 0038
.0025+. 0038
.035+. 01
.035+. 01
. 008+_. 006
.008+. 006
.055+_.023
.055+. 023
.009+. 005
.009+. 00 5
.001 +.002
.001+.002
.003+. 003
.003+_.003
.0003+. 0003
.0003+^.0003
LEGEND
Day
1
0.005+_.005
.0025+. 0038
.035+. 01
.035+_.01
.014+. 007
.009+_.007
.125+. 084
.082+^.046
.012+_.008
.012+_.008
.085+. 004
.103+. 004
.061 +.009
.246+. 021
.0002+_.0002
.0004+. 0003
Day
2
.0025+. 0038
.035+. 01
.004+_.004
0.059+_.05
. 005+_. 003
.073+_.009
.105+. 009
'.0003+.0003
Day
5
. 0084+_. 04
.01 37+. 0075
.035+. 01
.035+. 01
. 009+_. 006
. 007+ . 003
.065;+. 05
.029+. 01 2
.004+. 003
.015+. 004
.396+. 002
.067+_.001
.093+. 006
.330+. 01 5
.0003+. 0003
.0003+. 0003
Day
10
.005+. 005
.035+_.01
.011 +.007
.018+. 01 5
.011+_.009
. 054+.. 002
.068+. 009
. 0003+.. 0003
"Day" These numbers refer to the number of d
the encapsulated waste has been immers
"Unencapsulated These values were detenl)1ned for 400
Day
20
.0025+. 003
.009+. 0038
.035+_.01
.035+. 01
.008+. 006
.003+_.001
.004+_.004
.088+. 051
.013+. 004
.022+. 004
.938+. 01 2
.063+. 003
.069+. 006
.314+. 009
.0002+. 0003
.0004+. 0003
Day
30
.0025+_.003
.035+. 01
.005+. 003
.023+. 01 6
.017+. 005
.001+.. 002
.086+_.007
.0004+. 0003
Day
45
.008+. 003
.007+_.003
.035+. 01
.035+. 01
.008+_.003
.010+. 003
.032+. 01 6
.055+. 023
.015+_.006
.042+. 003
.072+_.004
.057+. 004
.069+. 01 5
.347+. 009
.0004+_.C003
.0004+. 0003
Day
60
. 0025+ . 0038
.017+. 005
.012^.004
057+_.029
.007+_.002
.161 +.003
.022+_.004
.0007+_.0003
Day
90
. 0025+_. 0038
.0025+. 0038
.015+_.0001
.035.01
.016+. 005
.013+. 003
.077+. 068
.061 +.002
.028+. 005
.053+. 002
. 1 66+ . 002
. 1 24+ . 002
.OT5+7U06
.178+. 01 4
. 001 +_. 0003
. 001 6+_. 0003
Day
120
.006+. 006
.012+_.0001
.015+_.008
.055+_.023
.017+. 009
.218+_.004
. 020+.~007
. 0011 +_. 0003
Unencap-
sulated Waste
0.33
325.20
.033
5.00
21.54
5,334.4
18,237.0
.0024
Dry
Analysis (W/W)
76,923.0
153,847.0
770.0
153,847.0
384,616.0
76,923.0
1-53,847.0
154.0
COMMENTS ON LEACHING SOLUTION
These encapsulated waste concentration values are
within the variation of the background "instru-
mental noise".
Same as above.
Same as above.
Same as above.
Same as above.
The sodium variations are probably due to con-
tamination introduced from handling.
These' variations are probably due to surface con-
tamination. There is no apparent change from
Day 1 to Day 120.
Some leaching may be occurring, however, at 90 days
0.0015 ppm Mercury was found_>n a beaker of HC1 fron
laboratory exposure only so it is difficult to
ascribe the Hg source.
ays "Dry Analysis" Part per million value of cation
ed. concentrations in the solid waste
sample based on a Weight/Weight
rams ratio.
of unencapsulated waste on 1200 ml of leach-
ing solution, which is equal to the encap-
-sulated material.
All values are reported as parts per mil'ion, PPM.
"Unencapsulated Wastes" refer to raw wastes subjected only to drying.
4]
-------
TABLE 4. PPM CATION CONCENTRATIONS IN THE SIMULATED OCEAN LEACHING SOLUTION
CATIONS
Cu
Cr
Zn
Ni
Cd
Hg
BLANK
.003+. 003
. 003+. 003
. 030+.. 028
.030+. 028
.016+. 001
.016+. 001
.004^.001
.004+. 001
.033+. 008
.033+_.008
.0003+.. 0003
.0003+. 0003
DAY
. 003+. 003
.003+. 003
.037+.. 037
.037+. 037
.008+_.005
.005+. 003
.055+. 021
.055+. 020
.021 +.004
.021+. 004
. 0007+ . 0003
. 001 4+_. 0003
DAY
2
. 003+_. 003
. 068+ . 003
. 007+.. 003
.107+.. 080
.020+.. 003
.0011 +.0003
DAY
.010+.. 003
.008+. 004
.07 7+.. 003
.051+. 025
.002+. 001
.019+. 003
.077+. 045
.079+. 034
.029+. 003
. 01 4+ . 003
.0011 +.0003
.0042+.. 0003
DAY
. 007+.. 003
.069+.. 005
.01 5+.. 004
.086+. 01 7
.025+.. 002
. 002+ . 0003
DAY
.008+.. 003
.010+. 003
.037+. 037
.046+. 023
.002+.. 001
.004+. 002
.033+. 025
.077+. 031
.01 7+.. 003
.012+.. 005
.0008+.. 0003
.0066+. 0003
DAY
.040+. 005
.028+_.028
.001 +.001
.037+.. 028
.016+.. 004
. 001 +_. 0003
DAY
45
.ooe+_.oo6
.007+. 003
.055+.. 028
.028+. 028
.005+. 004
.001 + . 001
.031 +.026
.023+. 023
.015+.. 001
.019+.. 004
. 001 1+_. 0003
.008C+.OOC3
DAY
60
.003+. 003
.030+. 028
.011 +.004
.004+. 001
. 025+.. 002
.0016+. 0003
DAY
90
. 003+ . 003
.003+. 003
.030+. 028
.025+. 025
.007+.. 002'
.007+. 003
. 055+_. 029
.004+. 001
.042+. 007
.031 +.003
. 0008+_. 0003
. 0068+_. 0003
DAY
120
.003+.. 003
.030+. 028
. 007+. 003
.004+.. 001
.042+.. 009
.0017+. 0003
UNENCAPSU-
LATED WASTE
91.40
0.34
1.50
0.40
983.5
1.05
DRY
ANALYSIS (W/W)
76,923.0
153,847.0
770.0
153,847.0
384,616.0
154.0
COMMENTS ON LEACHING SOLUTION
These encapsulated waste concentration values are
within the variation of the background "instru-
mental noise".
Same as above.
Same as above.
Same as above.
Same as above.
Jhe higher valjjes in the second samgle are probabl,y_
due to surface contamination. They level off at
Days 20, 45 and 90.
LEGEND
"Day"
These numbers refer to the number of days
the encapsulated waste has been inmersed.
These values were determined for 400 grams
of unencapsulated waste on 1200 ml of leach-
ing solution, which is 'equal to the encapsu-
lated material.
"Dry Analysis" Part per million value of cation
concentrations in the solid waste
sample based on Weight/Weight ratio.
NOTES:
All values are reported as parts per million, PPM.
"Unencapsulated Wastes" refer to raw wastes subjected only to drying
42
-------
TABLE 5. PPM CATION CONCENTRATIONS IN THE NH4OH LEACHING SOLUTION
CATIONS
Cu
Cr
In
t:i
Cd
Ca
He,
BLANK
. 008+_. 004
. -.008+. 004
.0031-003
.003+_.003
.001+.OC1
.CC1+.OC1
.C24+_.OC7
.C24+_.OC7
.001+.. 001
.OOH.001
.003+_.OC4
.003+. 004
.0003+. 0003
. 0003+ . 0003
DAY
1
.003+_.003
.003+_.003
.C06+_.C06
.ooe+_.ooe
.005+_.C02
.CC5+_.004
.024+_.OC7
.024+. 075
.001 +.001
.C14+.Cf3
.OSO+..CO-'
.C55+_.033
-CC03+_,C003
.COC3+..CG03
DAY
2
.005+_.005
. 005+.. 005
.001 +.001
.C52+_.022
.012+. 005
.056+. 004
.00041-0003
DAY
5
.009+_.G02
.012+. 003
.09G+.049
.098+_.0<9
.001 +.001
.007+. 003
.069+. 037
.022+. 01 3
' .013+. 006
.COG+.004
.044+.. 007
.05C+.025
.C004+.CC03
.CCC3+_.OOC3
DAY
10
. C06+ . 003
.OOS+_.004
. 005+_. 004
.025+_.011
. CC7+ . 003
.024+_.OC3
. 0004+.. CCC3
DAY
20
.C13+.003
.009+.. 003
.004+. 004
.098+. O'S
..C04+_.OG3
.C01+.001
.016+_.016
.C24+_.024
.CC6+_.003
.COS+_.G03
.(X7+.OG5
.050+. 025
-CCC7+.C003
.0005+_.0003
DAY
30
.008+_.006
.009+. 005
.CC1 + .001
.040+.. 028
.C20+_.004
.032+_.002
.001H.003
DAY
45
.008+_.008
.008+. COG
.005+. OOb
.003+. 003
.005+_.003
.OOH.OOl
.024+. 01 3
.022+. 01 5
.013+. 004
.009+. 003
.044+_.007
.065+_.025
.OOC5+_.0003
.0005+_.0003
DAY
60
.008+_.004
. 0033+_. 001
.OOH.001
.001 +.001
. 065+_. 046
.003+. 002
.028+. 004
.0008+. 0003
DAY
90
.008+. 004
. 008+_. 004
.0030+. 001
.003+. 003
.001 +.001
.09H.066
.032+_.032
.017+. 004
.013+. 002
.018+_.001
-050+_.025 '
.0015+. 0003
.001 4+.. 0003
DAY
120
.036+_.015
.003+_.003
.001 +.001
.088+. 044
.010+. 004
. 01 6+ . 003
. 001 3+_. 0003
UNENCAPSU-
LATED WASTE
414.0
710.9
17.4
1.0
94.0
23.0
0.26
DRY
ANALYSIS (W/W)
76,923.0
153,847.0
770.0
153,847.0
384, 61 6. -0
153,847.0
154.0
COMMENTS ON LEACHING SOLUTION
These encapsulated waste concentration values are
within the variation of the background "instru-
mental noise".
Same as above.
Same as above.
Same as above.
Same as above.
These variations are probably due to surface
contamination. There is no apparent change from
Day 1 to Day 120.
Some leaching may be occurring.
"Day" These numbers refer to the number of days
LEGE_ND the encapsulated waste has been immersed.
Waste" These values were determined for 400 grams
of unencapsulated waste on 1200 ml of leach-
ing solution, which is equal to the encap-
sulated material.
"Dry Analysis" Part per million of cation
concentrations in the solid waste
sample based on a Weight/Weight
ratio.
NOTES:
All values are reported as parts per million, PPM.
"Uncapsulated Wastes" refer to raw wastes subjected only to drying
43
-------
TABLE 7. PPM CATION CONCENTRATIONS IN THE AMMONIUM SULFIDE LEACHING SOLUTION
CATIONS
Cu
Cr
Zn
Ni
Cc!
BLANK
.018+. 002
.018+. 002
.009+. 009
.009+. 009
.006+. 006
.006+. 006
.030+. 030
. 030+_. 030
.073+. 010
.073+.. 010
DAY
1
.002+. 002
.018+. 002
. 01 3+. 006
.009+. 009
.050+_.003
.098+. 001
. 1 1 9+_. 064
.030+. 030
.053+.. 005
.075+.OOE
DAY
2
.G18+_.002
.004+_.002
.031 +.004
.094+. 051
.057+. 006
DAY
5
.002+.. 002
.039+.. 002
.009+.. 009
.004+.. 004
.035+. 004
.163+. 002
.124+. 066
.073+.. 040
.075+. 004
.142+. 006
DAY
10
.002+.. 002
.004+. 002
.028+. 002
.034+. 02 5
.095+. 003
DAY
20
.002+. 002
.002+. 002
.009+.. 009
.009+. 009
.060+. 001
.073+.. 001
.110+_.017
.056+.050
.012+. 07 5
.015+. 001
DAY
30
.018+. 002
. 009+_. 009
.063+. 004
.075+. 025
.006+.. 006
DAY
45
.002+. 002
. 002+. 002
.009+. 009
.009+. 009
. 083+.. 002
.070+. 001
.249+. 030
.060+. 050
.091 +.003
.073+. 010
DAY
60
.018+. 002
.009+. 009
.083+. 002
.249+. 030
.094+.. 003
DAY
90
.054+.. 002
.005+. 002
.009+.. 009
.009+.. 009
.121+. 001
.021 +.002
.233+. 028
.177+.. 023
. 094+. 003
.091^.001
DAY
120
.051 +.002
. 009+.. 009
.114+.. 002
.093+. 043
.096+. 003
UNENCAPSU-
LATED WASTE
2.9
233.4
0.08
2588.9
8.3
DRY
ANALYSIS (W/W)
76,923.0
153,847.0
770.0
153,847.0
154.0
COMMENTS ON LEACHING SOLUTION
These encapsulated waste concentration values are
within the variation of the background "instru-
mental noise".
Same as above.
Same as above.
Same as above.
Same as above.
LEGEND
"Day" These numbers refer to the number of days
the encapsulated waste has been immersed.
Waste" These values were determined for 400 grams
of unencapsulated waste on 1200 ml of leach-
ing solution, which is equal'to the encap-
sulated material.
"Dry Analysis" Part per million of cation
sontrations in the solid waste
sample based on a Weight/Weight
ratio.
NOTES:
All values are reported as parts per million,. PPM.
"Unencapsulated Wastes" refer to raw wastes subjected only to drying
44
-------
TABLE 6. PPM CATION CONCENTRATIONS IN THE NaOH LEACHING SOLUTION
CATIONS
Cu
Cr
Zn
Ni
Ccl
Ca
Hg
BLANK
.003+. 004
.003+. 004
.003+. C04
.003+. 004
.003+. 003
.003+. 003
.cm. 01 3
.019+. 01 3
.OIB+.307
.01S+_.007
.OC7+.007
.C07+_.OC7
.0003+. 0003
.0003+. 0003
DAY
1
. 003+_. 004
.OOC+_.005
.C14+_.005
.01C+_.C07
.11G+_.CC4
.104+.. 004
.019+. 01 3
.019+. 01 3
.012+. 006
.005+_.C01
-077+.CC7
-CC2+_.CC£
.0003+. 0003
.0003+_.C003
DAY
2
.013+_.003
.006+.. 005
.121 +.005
-012+_.C12
.OIH.OCC
.C63+_.C03
.OC03+.OOC3
DAY
5
.012+_.OC5
.02H.005
.C06+_.005
.003+_.004
.026+_.004
.04C+.001
.032+. 01 2
.07C+_.040
.004+. 003
.009+_.005
.037+.. 003
.033+_.C05
.0003+. 0003
.0003+_.0003
DAY
10
.024+_.005
.C03+_.004
.052+. 007
.019+_.C13
.C10+_.003
.011+_.C02
.0003+. 0003
DAY
20
.019+. 001
.031+. 010
.010+. 005
.009+. 007
.015^.003
.039+_.OC4
.OOS+_.008
.019+_.013
.005+. 004
.007+. 002
.C04+_.001
.006+. 003
.COC3+.0003
.0003+. 0003
DAY
30
.034+. 034
.003+. 003
.015+. 003
.OOE+_.006
.006+. 002
.030+.. 002
.0003+. 0003
DAY
45
.040+. 040
.OOG+.004
.003+. 003
.003+. 003
.017+. 003
.013+. 003
.006+_.006
. 1 1 9+_. 035
.002+. 001
.001+-. 001
.020+. 003
.019+. 003
.0013+. 0003
.0005+. 0003
DAY
60
.040+. 01 2
. 01 0+ . 004
.018+. 001
.0671-026
.025+. 01 7
012+.003
.006+0.0
.0003+. 0003
DAY
90
.017+. 009
.053+. 008
-014+_.009
.003+. 003
.019+. 003
.011 +.002
.073+. 060
.008+. 007
.005+_.002
.006+0.0
.006+_.006
. 0003+_. 0003
. 0005+_. 0003
DAY
120
.087+. 022
.008+_.001
.021 +.001
. 068+ . 042
.016+_.005
.006+. 006
.0003+. 0003
UNENCAPSU-
LATED WASTE
339.1
5,884.5
15,519.8
not detected
<0.2
1,500.3
44.3
0.005
DRY
ANALYSIS (W/W)
76,423.0
153,847.0
770.0
153,847.0
384,616.0
153,847.0
154.0
COMMENTS ON LEACHING SOLUTION
These encapsulated waste concentration values are
within the variation of the background "instru-
mental noise".
Same as above.
These values are probably due to surface con-
tamination. There is no apparent change from
Day 1 to Day 120.
Same as above.
These encapsulated waste concentration values are
within the variation of the background "instru-
mental noise".
Same as above.
Same as above.
LEGEND
"Day"
These numbers refer to the number of days
the encapsulated waste has been immersed.
"Unencapsulated These values were determined for 400 grams
of unencapsulated waste on 1200 ml of leach-
ing solution, which is equal to the encap-
sulated material.
"Dry Analysis" Part per million of cation
concentrations in the solid waste
sample based on a Weight/Weight
ratio.
NOTES: An values are reported as parts per million, PPM.
"Unencapsulated Wastes" refer to raw wastes subjected only to drying
45
-------
TABLE 8. PPM CATION CONCENTRATIONS IN THE CITRIC ACID LEACHING SOLUTION
CATIONS
Cu
Cr
Zn
Ni
Cd
N'a
Ca
Hg
BLANK
.003+.. 003
.003+. 003
.003+. 003
.003+.. 003
.001+.. 001
.OOH.001
.037+.. 037
.037+.. 037
.OOOC+.0006
.0006+. 0006
.001 +.0005
. 001 +_. 0005
.010+.. 010
.010+. 010
.0003+.. 0003
.0003+.. 0003
DAY
1
.008+. 004
.011+.. 009
.008+. 004
.002+. 001
.002+.. 001
.016+_.OC4
.037+.. 037
.055+.. 055
.03H.002
.09C+_.OOe
.ne+.co4
.255+.006
.061+.. 005
.360+.. 010
.0003+. 0003
. 0003+.. 0003
DAY
2
.005+. 005
.002+. 002
.003+. 001
.072+. 047
.C3H.002
.076+.. 001
.C4H.OOC
.OOC3+.COC3
DAY
5
.007 +.004
.013+.. 003
.004+.. 004
.023+.. 005
.006+.. 005
.01C+_.002
.054+. 031
.038+_.021
.037+.. 009
. 1 23+.. 007
.077+. 001
.224+. 002
.059+^.007
.502+. 020
.0007+. COOS
.0004+. 0003
DAY
10
.010+.. 007
.01H.004
.005+. 001
.C7C+.C20
.048+.. 003
.090+. 001
.ce3+_.oc6
.oooe+.ocos
DAY
20
.009+.. 008
.021 +.007
.005+. 003
.038+.. 004
.005+. 002
.015+. 002
.03C+.030
.C42+.019
.044+. 003
.141+.. 005
.054+.. 001
.249+.. 002
.C85+..006
.541 + .013
.008+.. 0003
.0004+.. 0003
DAY
30
.01 9+.. 004
.008+. 005
.001+..001
.024+.. 01 4
.044+.. 004
.094+.. 003
.207+.. 008
.0011+.. 0003
DAY
45
-011+.004
.022+.. 003
.011+.. 005
.030+. 007
.001 +.0005
.010+.. 002
.031 +..01 9
.065+.. DIG
.042+.. 004
.140+.. 004
.078+.. 003
.135+. 002
.129+. 003
.559+.. 022
.0004+.. 0003
.0006+.. 0003
DAY
60
.010^.005
.014+.. 005
.003+.. 003
.015+. 01 5
.039+. 002
006+ . 001
274+. 002
.0004+. 0003:
DAY
90
. 01 OjK 005
.025+. 004
.013+. 004
.052+^.005
.003+. 003
.018+. 002
.079+. 050
.194+.. 070
.038+. 006
. 086+. 004
.01 4+^.001
.111+.002
.290+.. 01 5
.573+. Oil
.0004+. 0003
.0004+. 0003
DAY
120
.010+. 005
.012+.. 004
.008+,. 003
.055+_.055
.052+. 004
. 035+.. 001
.345+. 01 4
.0005+. 0003
UNENCAPSU-
LATED WASTE
1,803.4
2,524.7
18,270.3
4,719.3
6,401.3
6,085.0
21,537.6
.004
DRY
ANALYSIS (W/W)
76,923.0
153,847.0
770.0
153,847.0
384,616.0
76,923.0
153,847.0
154.0
COMMENTS ON LEACHING SOLUTION
There is no apparent change in Day 1 to Day 120
in one set of data. The other set may represent
surface contamination as this block wa<= discolored
in areas.
Same as above.
These encapsulated waste concentration values are
within the variation of the background "instru-
mental noise".
Same as above.
Same as above.
These concentration values are probably due to
surface contamination. There is no apparent change
from Day 1 to Day 120.
An increasing trend is noted. This could be due to
surface contamination because a similar trend for Na
(above) which would be expected also is not observed
These encapsulated waste concentration values are
within the variation of the background "instru-
mental noise".
"Day" These numbers refer to the number of days
LEGEND the encapsulated waste has been immersed.
"Unencapsulated
Waste" These values were determined for 400 grams
of unencapsulated waste on 1200 ml of leach-
ing solution, which is equal to the encap-
sulated material.
"Dry Analysis" Part per million of cation
concentrations in the solid waste
sample based on a Weight/Weight
ratio.
NOTES: All values are reported as parts per million, PPM.
"Unencapsulated Wastes" refer to raw wastes subjected only to drying
-------
TABLE 9. PPM CATION CONCENTRATIONS IN THE HC1 LEACHING SOLUTION
CATIONS
Cu
Cr
Zn
Mi
Cd
iia
Cs
Hg
BLANK
.0025+. 0038
.0025+. 003S
.035+. 01
.035+.. 01
.005+.. 006
.008+. 006
.055+. C23
.055+.. 023
.OCS+.005
.009+. 005
.001+..OC2
.001 +.002
.OC3+.003
.003+. 003
.0003+. 0003
.0003+. COOS
DAY
1
.010+. 00
.020+. 0
.017+.. 006
.044+.. 01 5
.0123+..001
.024+. 004
.oes+.ceo
.C20+..CC7
.098+. 023
.111+..007
.128+. 002
.097+.. 097
.424+. 009
.OC12+..OC03
.003+. COOS
DAY
2
.009+.. 008
..007+.010
.008+.. 004
.075+. 033
.041+.. 034
.016+.. 008
.328+. 003
.567+.. 020
.OC2+..C003
DAY
5
.002+.. 003
.009+. 001
.023+.. 009
.100+.. 010
.010+. 002
.022+.. 003
.015+.. 01 5
.023+. 007
.117+.. 007
.133+. 001
.202+.. 001
.C75+..015
.363+..02C
.010+.. 0003
.019+. 0003
DAY
10
.001+..001
.017+. 009
.016+. 006
.042+. 021
.1C1+.08C
.029+.. 003
.157+.CC1
.121 + .070
.01C+.CGC3
DAY
20
.003+.. 005
.035+. 005
.01 5+.. 009
.112+.013
.005+.. 002
.022+.. 002
.048+.. 030
.025+.. 002
.117+.. 007
.121+.. 002
1.03+.. 007
.C5C+_.050
-317+..02G
.C1G+.CCC3
.040+. 0003
DAY
30
.013+. 010
.111 +.025
.003+.. 002
.C14+..007
.027+. 01 7
.C20+_.C02
.052+. 007
.062+.. 009
.C13+.OC03
DAY
45
.027+_.004
.046+. 007
.042+. 01 7
.077+.018
.OC4+_.C02
.017+_.002
.017+_.017
..022+_.005
.108+. 003
.356+. 01 3
.07C+.002
.081+_.007
.331+.. Oil
.014+..C003
.031+.OC03
DAY
60
.011 +.007
.030+. 005
.006+. 004
.039+. 022
.01 5+.. 003
.161 +.003
.022+..004
.01 35+. 0003
DAY
90
.028+. 004
.020+_.003
.035+. 01
.071 +..01 2
. 008+ . 003
.020+. 001
-029+_.019
.107+.. 058
.016+^.006
070+_.006
.166+. 002
.124+.. 002
.015+. 006
.1781.014
.0149+^.0003
.025+. 0003
DAY
120
.011 +.004
.035+. 01
.011 +.005
.168+.. 074
.019+. 002
.218+. 004
.01 3+.. 004
.01 89+. 0003
UNENCAPSU-
LATED WASTE
25,035.0
127,390.0
8,231.7
42,352.0
106,416.0
45,098.5
590,650.0
171.5
DRY
ANALYSIS (W/W)
76,923.0
153,847.0
770.0
153,847.0
384,616.0
76,923.0
153,847.0
154.0
COMMENTS ON LEACHING SOLUTION
These concentration values are probably due to
surface contamination. There is no apparent
change from Day 1 to Day 120.
These encapsulated waste concentration values are
within the variation of the background "instru-
mental noise".
Same as above.
Same as above.
Same as above.
These concentration values are probably due to
surface contamination and handling.
These concentration values are probably due to
surface contamination. There is no apparent
change from Day 1 to Day 120.
Some leaching may be occurring, however, at 90 days
0.0015 ppm Mercury was found in a beaker of HC1 from
laboratory exposure only so it is difficult to
ascribe the Hq source.
LEGEND
"Day"
"Unencapsulated
Waste"
These numbers refer to the number of days "Dry Analysis"
the encapsulated '.;aste has been immersed.
These values, were determined for 400 grams
of unencapsulated waste on 1200 ml of leach- MOTES-
ing solution, which is equal to the encap-
sulated material.
Part per million of cation
concentrations in the solid waste
sample based on a Weight/Weight
ratio.
All values are reported as parts per million, PPM.
"Unencapsulated Wastes" refer to raw wastes subjected only to drying
47
-------
TABLE 10.
CATION CONCENTRATIONS IN THE 10% DIOXANE LEACHING SOLUTION
CATIONS
Cu
Cr
Zn
Ni
Cd
Na
Ca
Kg
BLANK
.008+. 004
.008+. 004
.016+. 01 6
.016+. 01 6
.007+_.004
.007+. 004
0+0.0
0.0+0.0
.003+_.003
.003+_.003
.004+. 0035
.004+. 0035
.008+. 004
.008+_.004
.0003+_.0003
.0003+. 0003
DAY
1
.003+_.004
.008+.. 004
.008+_.001
.004+_.004
.014+. 007
.014+. 007
0.002+.001
0.0+0.0
.006+. 004
.011 +.007
1.01S+.010
.172+. 002
.029+_.OOS
.130+_.003
.0003+. 0003
.0003+. 0003
DAY
2
.005+_.005
.006+_.003
.009+_.002
.002+. 001
.006+. 004
.94H.012
.030+. 007
.0003+. 0003
DAY
5
.011 +.003
.007+_.004
.005+. 003
.008+_.001
.014+_.001
.023+. 004
.002+. 001
0
.004+. 002
.004+. 004
.548+. 004
.169+. 003
.012+_.001
.200+_.003
.0003+. 0003
.0003+. 0003
DAY
10
.002+_.002
.OOH.OOl
.006+. 003
.002+. 001
.003+. 001
.426+^.005
.008+. 007
.0003+. 0003
DAY
20
.005+. 005
.002+_.003
.005+_.001
.007+. 001
.003+. 003
.004+. 002
.002+. 001
0
.012+. 004
.005+. 004
.350+. 005
.145+. 001
.008+. 007
0.1 70+. 002
.0003+. 0003
.OOC3+.0003
DAY
30
.008+_.004
.005+. 005
.007+. 004
.002+_.001
.023+. 006
.388+_.009
.094+.. 005
.0003+_.0003
DAY
45
.008+. 004
.008+. 004
.002+. 003
.002+. 003
.007+. 004
.107+. 004
.002+. 001
.002+. 001
.024+. 006
.014+.. 003
.325+. 002
.291 +.002
0.1 03+.. 006
.076+. 005
.0007+. 0003
.0004+.. 0003
DAY
60
.012+. 008
.004+. 004
.010+. 001
.002+. 001
. 034+_. 005
.392+_.006
. 084+_. 004
. 0003+_. 0003
DAY
90
.041 +.01 3
.008+. 005
.004+. 004
.003+. 003
.008+. 001
.007+. 002
.002+. 001
.002+. 001
.046+. 004
.015+_.002
.405+_.005
.^58+. 003
.096+. 006
.015+. 001
. 0003+_. 0003
^0003+^.0003
DAY
120
.014+_.008
.004+. 004
.004+. 001
.002+^.001
.037+.. 005
.610+. 006
.146+. 010
..0003+.. 0003
UNENCAPSU-
LATED WASTE
5.9
71.6
1.6
5.5
19.5
4834.3
134.9
0.002
DRY
ANALYSIS (W/W)1
76,923.0
153,847.0
770.0
153,847.0
384,616.0
76,923.0
153,847.0
154.0
COMMENTS ON LEACHING SOLUTION
These encapsulated waste contamination values are
within the variation of the background "instru-
mental noise".
Same as above.
Same as above.
Same as above.
The cadmium in one sample is increasing. In
the other the values are within the variation
of the background "instrumental noise".
These concentration values are probably due to
surface contamination. There is no apparent
change from Day 1 to Day 120
Same as above.
These encapsulated waste contamination values are
within the variation of the background "instru-
mental noise".
LEGEND
"Day"
These numbers refer to the number of days
the encapsulated waste has been immersed.
"Unencapsulated
Waste" These values were determined for 400 grams
of unencapsulated waste on 1200 ml of leach-
ing solution, which is equal to the encap-
sulated material.
"Dry Analysis" Part per million of cation
concentrations in the solid waste
sample based on a Weight/Weight
ratio.
NOTES: 'All values are reported as parts per million, PPM.
"Unencapsulated Wastes-' refer to raw wastes subjected only to drying
48
-------
TABLE 11. pH VALUES OF LEACHING SOLUTIONS
Solution
Distilled Water
HCL
Citric
NaOH
MH4OH
Ocean
Dioxane
Ammonium
Sulfide
0 Day
6.3
6.3
0.3
0.3
2.2
2.2
11.5
11.5
11.1
11.1
6.1
6.1
4.8
5.3
8.8
8.8
1st Day
6.8
7.0
0.4
0.5
2.5
2.5
12.1
12.1
9.4
9.4
6.5
6.4
4.6
5.1
8.7
8.7
2nd Day
7.0
0.6
2.5
12.1
9.4
6.3
5.0
8.6
5th Day
6.8
6.5
0.7
0.7
2.8
2.8
11.8
12.0
8.8
8.9
8.4
7.5
6.7
6.2
8.7
8.7
10th Day
6.5
1.1
2.3
11.8
8.8
8.2
6.2
8.7
20th Day
6.6
6.8
0.3
0.7
2.1
1.9
12.9
12.5
8.6
8.6
9.4
9.6
6.0
5.7
7.2
6.8
30th Day
6.2
0.5
2.1
12.5
9.0
9.2
4.5
9.1
45th Day
8.5
7.5
0.9
0.8
1.8
2.0
12.7
12.9
8.9
8.8
9.3
7.8
4.7
5.7
8.7
8.8
60th Day
7.0
0.8
1.6
13.0
8.6
7.7<
4.7
9.0
90th Day
5.7
4.5
0.9
0.8
1.6
1.6
12.9
13.0
?.2
9.2
7.5
7.5
3.8
4.0
9.4
9.3
120th Day
6.1
0.8
1.7
13.0
8.2
7.7
4.2
9.2
10
-------
4.2 LEACHING PROCEDURE FOR ARSENIC CONTAINING WASTE
The arsenic waste described in Section 2.1, i.e., the waste containing
1-1/2% by weight monosodium methylarsonate, 49% sodium chloride and 49%
sodium sulfate, was agglomerated and encapsulated. Two blocks were utilized
in the leaching studies. The blocks were placed in 2 liter beakers, one
submerged in distilled water and the other in a 1.5 N HC1 leaching solution.
Table 12 gives data concerning arsenic and sodium concentrations of the
leaching baths over 80 days.
4.2.1 Arsenic Assay Method
The experimental procedure" and the analytical method used to determine
the concentration of the arsenic in the leaching baths is described below.
The sodium content was also determined in these solutions by atomic ab-
sorption spectroscopy using the parameters given in Table 2.
4.2.1.1 Technique
The glassware, blocks and solutions were prepared according to the pro-
cedures used for the composite heavy metals waste samples. The leaching of
arsenic containing blocks were conducted over a period of 80 days with sam-
ples being analyzed for their arsenic content at 1, 2, 5, 10, 20, 30, 45,
60 and 80 day intervals. A sample of the dry, untreated waste material was
also placed in the water and acid solutions and analyzed for its arsenic
content after 80 days of exposure to provide a comparative data point for
establishing the effectiveness of the encapsulation in containing this
hazardous material.
4.2.1.2 Method of Analysis
Inorganic arsenic is reduced to arsine, AsHj, by zinc in acid solution.
The arsenic is then passed through a scrubber containing glass wool im-
pregnated with lead acetate solution and into an absorber tube containing
silver diethyldithiocarbamate dissolved in pyridine. In the absorber,
arsenic reacts with the silver salt, forming a soluble red complex which
is suitable for photometric measurement. The absorption is then measured
50
-------
TABLE 12. PPM ARSENIC AND SODIUM CONCENTRATIONS IN DISTILLED WATER AND HC1 LEACHING SOLUTIONS
Day Day
Solution Blank 1 2
Distilled
Water <.01 <.01 <.01
Arsenic
1.5 N HC1 <.01 <-01 <.01
Distilled
Water .050+. 002 .191 +.005 .1291-003
Sodium
1.5NHC1 .002+. 001 .164+^.001 .076+. 002
Day Day Day Day
5 10 20 30
..o, .,, ,., ..
<.01 <.01 <.01 <.01
Day Day
45 60
,. ,
<.01 <.01
.148+.002 .189+..001 .178+. 001 All available solution
was used in arsenic
determination.
.059+. 003 .069+. 002 .150+. 002 All available solution
was used in arsenic
determination.
Day Unencapsu-
80 lated waste Comments
<.01 2,420 No arsenic was detected
in this leaching solution.
<.01 1,017 Same as above
.21+0 10,085.4 No sodium was detected. Day
1 and Day 80 values are with-
in the variation of the
"instrumental noise".
.176+.. 002 10,918.9 Same as above
LEGEND: Days - These numbers refer to the number of days the encapsulated waste has been immersed.
Unencapsulated Waste - These values were determined for 400 grams of unencapsulated waste
on 1200 ml of leaching solution, which is equal to the encapsulated
material.
Values are reported as parts per million, pptn.
Arsenic was determined by the silver diethyldithiocarbamate method.
Sodium was determined by atomic absorption spectroscopy.
-------
on a spectrophotometer at 535 nrillicrometers. A Beckman DK-2 spectrophoto-
meter was used for these determinations and was calibrated using standards
of 0.2, 0.4, and 0.6 ppm. The limit of detection for arsenic using this
method is 0.01 ppm. Duplicate determinations were conducted for each
analytical run.
4.2.2 Explanation of Table
The data reported in Table 12 for the arsenic levels in a sample of
unencapsulated waste material are equal to the concentrations that would be
obtained for 400 grams of waste in 1200 ml of solution after 80 days, which
is approximately equal to the weight of waste contained in each sample
block. If a zero absorption reading was obtained, the concentration value
was reported as less than 0.01 ppm limit of detection. Due to the nature
of this waste the solutions were also analyzed for their sodium content by
atomic absorption spectroscopy.
4.3 ASSAY OF ENCAPSULATED SODIUM CHLORIDE
Two encapsulated blocks of sodium chloride weighing 538.6 g and 536.8 g
were submerged in water over a period of six months. The blocks were peri-
odically removed and weighed. No weight change of the blocks could be
observed which exceeded the sensitivity of the determinations, i.e., j^O.l g.
4.4 DISCUSSION OF LEACHING TESTS
No definite trend of increasing concentrations of any of the monitored
metals was noted in any of the leaching baths Tables 3 to 10. Mercury may
be an exception in two cases: HC1 and NH.OH solutions. However, laboratory
contamination may account for this increase since 0.0015 ppm mercury was
observed in a blank sample of the HC1 leaching solution after 90 days of
exposure in,the work area. Analogous sample contamination have been ob-
served by others.*
Bothner, M. H. and Robertson D. E.: Analytical Chemistry, Vol. 47,
No. 3, March 1975, page 592.
52
-------
The erratic values observed for the concentrations of any one metal
from one time period to the next are due to the low concentrations present.
This results from analyzing for metal ions at the limits of detection and,
therefore, includes the instrumental noise.
Calcium and sodium in trace amounts appear to be surface contaminants
of tested specimens. Since sodium is present in hand oils and both calcium
and sodium are present in tap water, slight traces of sodium and calcium
could be left as residues on all washed surfaces. Trapped particulates on
the surface may account for some concentration readings, i.e., cadmium in
the distilled water solution, where the ion value after the first day of
immersion is the same as after 120 days.
Of particular importance, Tables 3 to 10 show that the concentration
of any given metal in the encapsulated waste is low and equivalent in all
the leaching baths after 120 days of immersion. Yet the concentration
values of the metals of unencapsulated waste are usually high and vary
widely with the nature of the bath employed. Particularly noteworthy are
the results given in Tables 8 and 9. These show that excellent retention
of heavy metal contaminants was realized even in the presence of strong
solvents such as citric acid and HC1. Table 11 shows that the pH of the
solution did not vary during the leaching period, the slight changes in
the values given being attributed to the margin of error of the deter-
mination. And Table 12 shows that retention of arsenic and sodium was
excellent. Such data indicate that essentially equal effectiveness is
maintained by the resin jacket in retaining a wide range of heavy metal
contaminants under a broad range of leaching conditions.
53
-------
5. MECHANICAL TESTS
Mechanical testing was performed on the .encapsulated blocks of
hazardous waste materials to determine their behavior during handling,
transportations storage and disposal, as well as subsequent environmental
exposure. A test plan was made to evaluate the mechanical properties of
the encapsulated waste (Table 13). Thirteen specimens of a blend of
mixed wastes were employed (composition and fabrication method given in
Section 2.2 and Section 3.3, respectively) and subjected to the mechanical
testing.
5.1 COMPRESSION
The compression test indicates the ability of the specimens to with-
stand loads at the disposal sites. The test is based on ASTM-C-39-71, but
was modified to use cubic specimens. The ultimate compressive stress of
the specimens was defined as the maximum load in the load-deformation
curve (Reihle testing maching) or the maximum indicated load using the
Cal-Tester testing machine, divided by the cross-sectional area of the
specimen.
5.2 FREEZE-THAW TESTING
The test was employed to determine the ability of the jacketed blocks
to withstand thermal cycling in a landfill environment. The test is a
modification of ASTM-C666-71 and consists of thermal cycling of the jack-
eted blocks alternately in a -10°C salt/ice bath and 100°C boiling water.
The cycles were of 15-minute duration (16 full cycles per day) with the
blocks being stored in a freezer during overnight periods. The tests were
continued for 75 half-cycle temperature changes and then they were tested
for ultimate compression strength as discussed in the preceding section.
54
-------
TABLE 13. MECHANICAL TESTING PROGRAM FOR HAZARDOUS WASTE
ENCAPSULATION PROGRAM
#
1
2
3
4
5
Test
Compression
Freeze-Thaw
Impact Strength
Puncturability
Bulk Density
Number of Specimens
Employed
3
3
3
1
3
5.3 IMPACT STRENGTH
This test indicates the ability of jacketed blocks to withstand mechanical
impact as may occur during transportation or dumping of the blocks. While a
standard dart type impact test such as the Izod or Gardner tests would be
desirable for comparison with other materials, these tests require a specimen
of specific geometry using a flat .060" to .125" thickness specimen. There-
fore, a drop test was utilized for the cubic specimens which was a minor
modification of ASTM D997-50-71, Impact Strength of Cylindrical Shipping
Containers. The specimens were dropped onto a steel plate 50 times from
a height of 6 feet, followed by 15 drops from 10 feet and 30 feet.
5.4 PUNCTURABILITY
This test was designed to measure the resistance of the jacketing
material to puncture by sharp objects. Initially, Federal Test Method 101B,
Puncture Resistance, was chosen as the test method, but the configuration of
the specimens and jacket thickness precluded the use of this method to obtain
satisfactory data. A qualitative test was then employed in which a pointed
tip steel fixture was made for use with the compression fixture in the
55
-------
Cal-Tester testing machine. Figure 29 gives the dimensions of this test
fixture. This test is qualitative, but will indicate the general mode of
failure of the tested specimens as well as penetration force. Data were
obtained for the jacketed specimens in the testing. A loading rate of
.050"/minute was used.
5.5 BULK DENSITY
Bulk density measurements were performed on inner core blocks of the
mixed hazardous waste. This was accomplished by carefully weighing and
measuring three blocks and determining an average bulk density and the
deviation from the average for the individual specimens.
5.6 RESULTS OF MECHANICAL TESTING
The results obtained in mechanical testing are provided as follows:
Compressive Strength of Virgin Products 1523 psi (87)^ '
Compressive Strength after Freeze-Thaw 1335 psi (228 r
Impact Strength withstands 30 ft drop'3'
Puncturability 700 pounds' '
Bulk Density of Agglomerate 92 lb/ft3 (.14)^
(1) Standard deviations given in parenthesis. Figure 30 shows
a typical loading deflection curve in compression of en-
capsulated products.
(2) The property determination and observation of specimens
indicated that the encapsulated products are stable in
freeze-thaw.
(3) Figure 31 shows a specimen after cumulative 6 foot, 10
foot, and 30 foot drop exposures.
56
-------
T
.6"
1
Dia. .711"
1-1/2"
Figure 29. Jig Used For Puncturability Testing
(4) It required a 700 pound force to penetrate the 1/4 inch
jacket to the surface of the encapsulated agglomerate.
No fracture on crazing occurred in the vicinity of the
puncture.
(5) Observation of the surfaces of the agglomerates showed
homogeneous distribution of the particulates.
57
-------
14000
12000
10000
6000
4000
2000
5.0 7.5
DEFLECTION ( % OF ORIGINAL BLOCK HEIGHT)
10.0
Figure 30.
Load-Deflection Curve for Compression Testing of
Jacketed Block Specimen
5.7 DISCUSSION OF RESULTS
Within the constraints of the program only preliminary mechanical
evaluations could be carried out. The limited number of tests and specimens
employed does not provide at this point sufficient information to completely
characterize the mechanical performance response of encapsulated wastes
under real life conditions. However, the results do indicate that high
mechanical performance will be achieved.
The magnitude of the compressive strengths showed encapsulated products
to be equivalent in strength to Portland cement. They should be capable of
sustaining the unidirectional pressure of 1500 psi (equivalent to a 3000
foot column of water).
58
-------
Figure 31. Jacketed Specimen After Impact Testing
Excellent product integrity is expected under actual freeze-thaw
conditions. The temperature range employed in this study was greater
than that likely to be encountered in a landfill, yet the products
maintained functional integrity. Furthermore, the products withstood the
additional stress of thermal shock. This stress although not present in
a landfill may be encountered in product fabrication, handling and tran-
sportation.
In the impact test, the products were dropped from appreciable heights.
With the exception of deformation of the edges, the products sustained the
stress of impact without apparent damage. Under use conditions, the pro-
ducts after being dropped from the bed of a truck either in transport or
in charging a landfill should continue to maintain functional integrity.
The requirement of 700 pounds pressure from a directed, pointed metal
jig to penetrate the jacket of the products showed that the products are
characterized by outstanding ability to withstand puncture. Even with
penetration, no cracking, crazing, or indeed any other indication of
59
-------
failure occurred in the vicinity of puncture. The product jacket under
stress of puncture alleviates the stress plasticly, thus conserving the
hazardous consignment. Only with complete penetration of the jacket will
the contaminants be exposed to the environment. And even then, the amount
of exposure will be limited to the area formed in pertrusion by the
puncturing object. No spillage will occur because the contaminants are
confined in a matrix.
The density of the products are in the lower range of the density
characterizing the earth, i.e., 90 to 200 Ibs/ft . Ground phosphate
rock through 8 mesh exhibits about 100 Ibs/ft bulk density.
Observation of the specimens after testing gave rise to the conclusion
that future specimens must be fabricated without sharp edges. All of the
evident damage to the specimens in testing was seen on the edge of the
samples, see Figure 31. The cubic and rectangular shapes are desirable
because they contribute to efficient use of space desired in transporting
and perhaps even in final disposal of the encapsulated wastes. As a
result, it is desirable to retain these configurations as much as possible.
But future specimens must be characterized by rounded rather than sharp
edges. The determination of the optimum shape of an encapsulated waste
product should be addressed in future work.
60
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6. DEVELOPMENT OF THE GENERAL PROCESS AND PROCESS ECONOMICS MODEL
Concurrent with work relative to determining the technical character
of the TRW process and to demonstrating the performance properties of its
products, additional work was directed to defining the nature of a large
scale process and to assessing its associated costs. In this work element,
a mechanical means was set forth for fabrication of large-sized passivated
waste products; and the dimensional nature of cost effective products was
estimated. Attendant equipment required for plant operations, and a plant
operational procedure were summarized in a Process Flow Diagram. Based
upon the structured process, a computer model was provided and it was em-
ployed to perform economic evaluations. From these evaluations, the cost
was determined for producing products; cost sensitive areas were identified
for additional investigation in order to further reduce costs.
6.1 PROCESS DEVELOPMENT
In the development of the engineering process, a mechanical means and
technique suitable for large scale passivation operations was set-forth to
carry out agglomeration and resin jacketing of hazardous wastes. A metal-
lic sleeve that is detachable from a stepped platform (Figure 32) forms a
mold for agglomerating resin coated particulated waste. Thermal energy is
transmitted to the waste while moderate mechanical pressure is applied.
The waste is immobilized by the thermosetting reaction of the resin and a
free standing agglomerate is thus obtained upon withdrawing the sleeve. A
second sleeve of larger dimensions is lowered about the agglomerate followed
by evacuation of the air from the annul us formed between sleeve and agglom-
erate. Powdered polyethylene is then sucked into the annul us. Suction
would be applied through a port beneath the agglomerate. Heat is applied
through the sleeve to melt the plastic and, after cooling, a five-side
jacketed agglomerate is produced. The agglomerate is then righted for
final jacketing. A seamless seal between the "bottom" and "side" jacket
is effected because the "lips" of the "side" jacket are remelted during
the final jacketing operation. The agglomerate is thus thoroughly encap-
sulated by a continuous resin jacket.
61
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Figure 32. process Concept
SLEEVE
AGGLOMERATE
PLATFORM
62
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This agglomeration and encapsulation technique does not require
molten resin to be employed outside the mold. Metallic tubes, screw con-
veyors, and mechanical rams required for molten resin delivery systems are
not necessary. Flexible rubber hoses can be readily employed for delivery
of powdered resin at room temperature to the mold. As a result it is
likely that construction and equipment associated with the latter technique
will be lower with respect to complexity and costs.
With the above described mechanical means for product fabrication in
view, the determinations of dimensions of cost effective products are
given in the following section. This is followed by the section showing
plant operations in the Process Flow Diagram.
6.1.1 Determination of the Dimensional Nature of Products
The dimensional nature of encapsulated waste products was estimated
through determinations of their cost effective size. On the one hand,
it is desirable economically to conserve resin employed for jacketing by
encapsulating larger agglomerates. On the other hand, the expense con-
comitant with larger equipment and the additional time required to complete
agglomerate formation counteract the advantage derived through reduced
resin costs. Thus, the estimations of the size of products were related
to thermal conductivity of the product which determines residence time in
heating, required oven size, and the amount of required jacketing resin.
Heat transfer calculations were carried out on the molding and curing
processes using the graphical solution of the three dimensional heat con-
duction equation.* These calculations assume that the unfused agglomerate
has a thermal conductivity of 0.4 Btu/hr ft2°F/ft and a specific heat of
0.2 Btu/lb°F. These values are typical of insulating materials and were
utilized due to lack of data specific to this area. Oven sizes were
calculated for three agglomerate block sizes, 500, 1000, and 2000 pounds,
Me Adams, William H., Heat Transmission, 1954, Tosho Insatsu Printing
Co., Ltd., Tokyo Japan
63
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based on the heat transfer considerations. (The blocks were assumed to be
cubes and the density based on two hazardous waste determinations was
taken to be 100 lbs/ft3.)
The required curing oven capacity increases as the block size increases
since: (1) the time necessary to heat the block increases, and (2) the
oven capacity increases in proportion to the residence time since the
mass flow rate through the system is constant. The calculated cure time
for various size blocks is presented in Figure 33. (The space between
blocks was assumed to be constant at 1 foot.) Also, the required jacketing
on a pound-per-pound of waste basis was determined for each of the three
block sizes. Both of these parameters, oven size and pounds jacketing/1b
waste, versus block size in pounds are shown in Figure 34. From this
figure it appears that the optimum block size is approximately 1000 pounds,
and is somewhat greater than two feet on edge. This conclusion is based
on the following points:
1. The costs of oven and the jacketing are proportional to the
size of the oven and the amount of jacketing material.
2. The oven size versus block size graph is nearly linear (i.e.,
constant slope for block size less than 1000 Ibs). For
block sizes greater than 1000 Ibs the slope begins to in-
crease and the curve appears to become exponential. There-
fore, any block size less than 1000 Ibs is acceptable with
respect to oven size and the related cost.
3. The jacketing requirement versus block size is nearly
linear for block sizes greater than 1000 Ibs but approaches
exponential form for block sizes less than 1000 Ibs.
Therefore, any block size greater than 1000 Ibs is accept-
able with respect to the jacketing.
64
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20
o
I 18
16
e
o
n
o
(O
8 12
% 10
o>
o
s_
o
Surface Temperature = 400°F
T; = Initial Temperature
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Block Size, Ib
Figure 33. Time Required for Center to Reach 300°F as a Function of
Agglomerate Size
65
-------
ro
O
Ul
O
I I I
,05
=«=
04 =:"
»«
oo
03
02
.01
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
BLOCK SUE, #
Figure 34. Oven Volume and Jacketing Resin Required as
a Function of Agglomerate Size
66
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4. From the points noted above, it is concluded that 1000 Ibs
is the optimum block size with respect to oven size and
jacketing.
6.1.2 Process Flow Diagram
The process flow diagram for the encapsulation of solid hazardous
waste is presented in Figure 35. The mass balances that are detailed later
in Section 6.1.3 are presented alongside the flow diagram and are broken
down into flow rates of the various components.
In the process, dry, particulated hazardous wastes are coated with
a formulated polybutadiene solution. The solvent (acetone was employed
in this work) facilitates the coating of the particulates; subsequently,
the solvent is evaporated and then condensed for recycle. The polybutadiene
solution is prepared in the process by combining delivered, viscous poly-
butadiene liquid resin with solvent and additives.
An alternate method for preparing the polybutadiene solution is to
polymerize butadiene in the solvent recovered from drying of the solution
wetted wastes. This can be readily carried out by employing the Swarc
synthesis method. In this method butadiene rather than viscous resin,
would be delivered to the plant site. This method avoids the handling of
viscous resins, an operation which may be awkward and costly.
The resin coated particulated wastes are agglomerated by heating and
consolidation is complete when the center of the agglomerate reaches 300°F.
The material is then uniformly hard. This consideration was employed in
the process determination and cost estimations. It remains to be deter-
mined, however, whether consolidation to this extent is necessary in order
to realize high performance products. If not, heating agglomerated wastes
in ovens could be eliminated. The operation would be reduced to fusing
compacted resin coated wastes at the surface of the compact. The resulting
agglomerate would then be characterized by a stiff, tough surface encap-
sulating an unfused waste compact. Subsequently, the ensemble would be
67
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resin jacketed by employing the mechanical means described previously. The
processing scheme discussed in the following paragraphs utilizes liquid
polybutadiene resins and curing ovens.
The dry waste is transported from storage to a pug mill by means of
an enclosed conveyor belt. The storage for the waste consists of an under-
ground silo with a hatch through which the silo is filled. To prevent
dust from getting into the air and moisture from condensing in the silo,
check valves to the bag filters and from the condenser are installed; hence,
any exhausted air passes through the bag filters and any inleted air passes
through the condenser. The pug mill coats the dry waste with the acetone-
polybutadiene mixture. The acetone-polybutadiene is mixed in a closed tank
using a propel lor-type agitator. These components are pumped into the
mixing tank from storage and recycled at a 5:1 acetone: polybutadiene
weight ratio.
The coated waste is transported by a screw conveyor to the top of the
rotary tray drier. The coated waste flows downward and is in contact with
hot, rising nitrogen gas which evaporates the acetone completely from the
coated waste. The nitrogen leaves the drier, flows through a bag filter
which removes any particulates, and combines with vent streams from the
pug mill and mixer into an acetone condenser. The liquid acetone is
pumped to the mixer and the nitrogen is reheated using steam and is recycled
(with make-up nitrogen added as needed) through the drier.
The solids (polybutadiene coated waste) leave the drier and are sent
along with particulates recovered from the bag filters to the agglomerate
mold. The residence time in this mold is about twenty-four minutes under
slight pressure and a surface temperature of 400°F. Steam provides the
necessary heat to effect curing of about three inches of the waste block.
The agglomerate block is transferred to the curing oven for about
eleven hours to cure the block completely. Heating is accomplished by
routing stack gases from the steam boiler to the oven. This gas is then
exhausted to the atmosphere through a catalytic converter to remove any
68
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organics. Jacketing the agglomerate is effected with powdered polyethylene
as described previously yielding a five-side jacketed block. The partially
coated (5 sides) block leaves the coating mold and is righted so that the
uncoated surface is on top. The top surface is jacketed and the block is
then sent to storage.
6.1.3 Mass and Energy Balances
Mass and energy balances around the pieces of equipment shown in
Figure 35 were carried out to determine the amount of each component in the
various streams. The mass balance is presented in Table 14. The assump-
tions used were:
(1) 20,000 tons dry waste processed per year.
(2) Density of the waste (compacted in mold) is 100 Ibs/ft ;
this is based on measurements of two hazardous waste samples.
(3) Specific heat and thermal conductivity of the unfused waste-
resin agglomerate is equal to that of insulating brick; hence,
cp = 0.2 Btu/lb.°F
k = 0.4 Btu/hr.ft2-°F/ft
(4) Temperature of process water for condenser is 80°F.
(5) Acetone to polybutadiene ratio is 5:1 by weight.
(6) Steam plant has efficiency of 70%.
(7) Heat efficiency of agglomerate mold is 90%.
(8) Surface temperature of waste agglomerate is 400°F during
block formation.
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(9) Temperature in curing oven is 400°F; efficiency is 90%.
(10) Heat efficiency of drier is 90%; other losses in the drier
system are negligible.
(11) Heat losses in steam pipes negligible.
(12) Blocks are cubes weighing approximately 1000 Ibs (weight
is actually slightly above 1000 Ibs).
(13) Polybutadiene concentration in blocks is 3% by weight.
(14) Vent losses from mixer and pug mill are 2% and 3% re-
spectively.
(15) Solids leaving in nitrogen stream are about 100 Ib/hr.
(16) Efficiency of bag filters is 99%.
6.1.4 Equipment Costs
The installed equipment cost for the process was calculated using the
technique presented by Guthrie. This method applies a "bare module factor"
to the f.o.b. cost of the equipment to give the installed cost. Data from
files, vendors, and other available sources was used to carry out these
calculations. The results are presented in Table 15.
6.2 PROCESS ECONOMICS COMPUTER MODEL
The final task of the engineering effort was the development of the
process economics model and an economic analysis of the process incorpo-
rating the model. This task is described below.
71
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TABLE 15. ; INSTALLED EQUIPMENT COST
Equipment
Acetone Storage Tank (30 days)
Polybutadiene Storage Tank (30 days)
Waste Storage Silo (30 days)
Polyethylene Storage Tank (30 days)
Mixer (260 gallons, closed tank)
Pug Mill
Screw Conveyor
Rotary Tray Drier
Acetone Condenser (Shell and Tube)
Heat Exchanger (Double Pipe)
Bag Filters
Agglomerate Molds (2 required)
Curing Oven
Coating Mold
Block Turnover Mechanism
Coating Cap
Powdered Polyethylene Delivery System
Steam Boiler
Blower (stack gases to oven)
Blower (N2 gas to drier)
Pump (acetone feed)
Pump (acetone recycle)
Pump (PB feed)
Pump (acetone/PB feed)
Enclosed Conveyor Belt (200 ft)
Conveyor Belt (stream 3-4; 500 ft)
Conveyor Belt (stream 4-5; 300 ft)
TOTAL =
Installed Cost, $
5,400
21,000
132,000
24,000
2,900
70,900
6,000
433,000
10,000
1,500
12,900
100,000
30,000
50,000
40,000
15,000
206,400
22,000
1,500
2,700
1,000
1,000
3,000
1,000
62,000
75,000
51,000
$1.38 x 106
72
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A computer program was written in BASIC language to carry out an eco-
nomic study of the encapsulation process. Parameters which can be changed
to study their effect on the cost are: (1) size of the plant, (2) cost
of the raw materials (3) percent polybutadiene binder used, (4) dewatering
cost (associated with sludges), (5) equipment changes in the encapsulation
process, and (6) the labor force. The program was written so that it can
be used simply by following the instructions printed at the terminal.
The computer program was written such that the operator may make de-
sired changes while in contact with the program. A logic flow diagram was
drawn up prior to the actual writing of the program to insure that all
options were included. This logic is presented in Figure 36 and the actual
program listing which is based on the program logic is presented as Table
16. The initial data used in running the program are from the base case
calculations. Each time the operator calls the program from disk storage,
the data are read to insure that each variable has a nonzero value. The
operator may then run the base case or change any parameter. Two options
o
are available with respect to parameter changes: (1) S (plant size/base
plant size), D (dewatering cost), and C(N) (raw material costs) may be
changed simultaneously, or (2) any one of the six parameters previously
listed may be changed individually. After the appropriate change is
entered, the program initiates the necessary calculation scheme and prints
out the results and value of each parameter. To assist the reader in
understanding the program, a typical session along with an explanation of
each step is presented in Table 17.
6.2.1 Parametric Studies
A series of economic evaluations was undertaken to determine the
significant factors in the overall cost of the encapsulation process. A
breakdown of the costs for the base case, which does not account for de-
watering costs, showed that about 50% of the total cost was attributable to
the raw material requirements, about 25% of the cost was attributable to
the labor force requirements (assumed 5 positions per shift) and the re-
maining cost was associated with the equipment costs. The operating costs
for the base case are presented in Table 18.
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TABLE 16. COMPUTER PROGRAM LISTING
1 VARoZERO
2 STRING A$,Z$
5 DIM B<20>,X<20>
10 FOR 1=1 TO 13
15 READ B(I)
20 NEXT I
25 DATA 182.4,29.2, 3, 12. 4, 70. 9, 450* 2. 9* 245. 5* 65. 10O, 12.9* 3.5*200
30 REM BCD IS BASE COST OF ENCAP EQMNT,K$; 4= SCREW CON, 13=MLTN PE DELIV.
35 FOR 1=1 TO 13
40 READ X(I)
45 NEXT I
50 DATA .60, .70*. 52, .75* 66, . 45* . 50* .65,0, 1,. 68* . 8 5* . 40
55 REM XCI) IS SIZE EXPNT; XC9>=0 IN ALL CASES FOR S2/S1, 4.8,X<10i=1
60 FOR N=l TO 4
65 READ R(N)
70 NEXT N
75 DATA 1.236E6, 1.386E6, 7.92E3, 1.228E6
80 REM R=AMT RAW MTRL, #/YR, BASE CASE; 1 = PB, 2=PE* 3=ACETONE, 4=N2, SCF/YR.
85 FOR N=l TO 4
90 READ C9 THEN 160
155 LET T=T+B(I)*2
157 NEXT I
160 LET T=T+B(I)*StX(I)
162 NEXT I
165 LET M1»T*F1
170 M2=F2*M1,F4=F2*M1
175 LET D1 = F3*M1
180 LET L2=L*S
185 LET U1 = U*S
190 LET C1 = CC1)*P3*S*R(1)
195 FOR N=2 TO 4
200 LET C1 = C1 + C(N)*S*R(N)
205 NEXT N
210 REM T=INST EQ CST,M1=MFG CAP,M2=MNT CST, F4=F. I ., Dl= DEP,L2=LBR, Ul-UTI
+ L,C1=RAW MAT CST
75
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TABLE 16. (CONTINUED)
215 LET W=/CS*S1>
220 LET W1 = W+D
225 IF Ll=l THEN 265
226 PRINT
227 PRINT
230 PRINT"RAW MATERIALS COSTl PB* PE* ACETONE*NITROGEN* IN KS/BASE UNIT"
235 FOR N=l T04
240 PRINT C(N)
245 NEXT N
246 PRINT
250 PRINT"SIZE=":S*Si;"% PBs"»P3*Pl; "DEWATERING COST»"l D; "LABOR»"tL2
251 PRINT
255 PRINT"COST LESS DEWATERING* $/TON="* W* "COST* $/TON»"» Wl
256 PRINT
257 PRINT
260 GO TO 345
265 PRINT"EQUIPMENT CHANGE MADE AS FOLLOWS"
270 FOR K=l TOP
275 PRINT Y$*X
305 NEXT I
310 FOR N= 1 TO 4
315 PRINT R(N)*C
320 NEXT N
325 PRINT D*U*L*F1*F2*F3*S*P3
330 PRINT"IF YOU WANT TO RUN ENTER 1*CHNGE DATA* 2, END RUN* 3"
335 INPUT F
340 ON F GO TO 145*345*610
345 PRINT"ENTER 1 FOR 1 PARAMETER CHNG* 2 FORM CHNG*OR 3 TO END RUN"
350 INPUT M
355 ON M GO TO 390*360*610
360 PRINT "ENTER S*D*CCN>"
365 INPUT S*D
370 FOR N=l TO 4
375 INPUT C(N)
380 NEXT N
385 GO TO 145
390 PRINT"WHICH PARAMETER DO YOU WANT TO CHANGE?"
395 PRINT"ENTER D FOR DEWATERING COSTS* C FOR RAW MAILS COSTS"
396 PRINT"P2 FOR % PB IN AGGLOMERATE* E FOP EQUIPMENT CHANGE"
397 PRINT"S2 FOR SIZE IN KTONS DRY WASTE THRU PUT PER YEAR"
398 PRINT"L FOR LABOR FORCE CHANGE"
400 INPUT ZS
405 IF Z$o"D" THEN 425
410 PRINT"ENTER DEWATERING COST IN S/TON D. S.W."
415 INPUT D
420 GO TO 220
425 IF Z$<>"C" THEN 470
430 PRINT"ENTER Jt J=NUMBER OF RAW MATLS COSTS TO BE CHANGED"
76
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TABLE 16. (CONTINUED)
435 INPUT J
440 PRINT-ENTER N AND CCN>; N=NTH COMPONENT/ CCN )= COST ,KS/UNIT"
445 LET J=J-1
447 INPUT N
450 INPUT CCN)
460 IF J<>0 THEN 440
465 GO TO 190
470 IF Z$o"Pg" THEN 515
475 PRINT-ENTER % PB IN AGGLOMERATE;RECALC BASE COST EQj 1= 1, 4* 7, 8"
480 INPUT P2
485 LET P3=P2/F1
487 PRINT-INPUT 1=1*4,7*8 ON NEXT LINE"
490 FOR H=l TO 4
495 INPUT I
500 LET BCI>=BCI>*P3tXCI>
505 NEXT H
510 GO TO 145
515 IF Z$<>"E" THEN 560
517 LET Ll=l
520 PRINT "ENTER K; K=NUMBER OF EQUIPMENT CHANGES TO BE MADE"
525 INPUT K
530 LET P=K
532 PRINT-ENTER I, BC I >,XC I >> Y$CK>; I=ITH COMPNT* YA»CHNG DESCPTN"
535 INPUT I
540 INPUT B(I)jX(I),Y$(K)
545 LFT KfK-1
550 IF K=0 THEN 145
555 GO TO 532
560 IF Z$<>"S2" THEN 585
565 PRINT-ENTER PLANT SIZE IN KTONS D.S.W. PER YEAR"
570 INPUT S2
575 LET S=S2/S1
580 GO TO 145
585 IF Z$<>"L" THfcN 130
590 PFINT"ENTER. NUMBER OF POSITIONS TO BE FILLED PER SHIFT"
595 INPUT G
600 LET L2=95*G
605 GO TO 215
610 END
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TABLE 18. OPERATING COSTS - $1000/YEAR
Utilities
Labor
Maintenance
Depreciation
Factory Indirects
Raw Materials
Cost = $1818.7/20 = $90.93/Ton
Cost = $90.93/Ton
Cost * $91/Ton
Each of the parameters given in Section 6.2 was varied holding all
other parameters constant to determine individual effects on the overall
cost, to determine the relative effect of the parameters, a plot of the
nondimensionalized operating cost (operating cost/base operating cost) vs
nondimensionalized parametric values (value/base value) was constructed.
Since the base cost of dewatering was taken as zero, the dewatering para-
meter could not be presented in this fashion. The graph (Figure 37) shows
that increasing size will decrease cost; decreasing the values of the
other parameters will also lower the cost. Raw materials cost (total) is
shown to be the most effective means of lowering the operating cost; labor,
equipment cost, and amount of polybutadiene in the agglomerate all have
about the same effect on the operating cost. The following paragraphs
deal with each study separately. It should be noted, however, that
dewatering costs are not included except in the case where dewatering cost
effects are examined.
The cost of encapsulation as a function of plant size, where size is
amount of dry waste processed per year, was investigated for two cases:
(1) 3% polybutadiene binder, and (2) 5% polybutadiene binder. The results
are plotted in Figure ;38. The results show that the change in binder con-
tent had no effect on the shape of the cost vs size curve. The results
79
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C/1
O
CD
a:
LiJ
a.
o
to
o
LLl
O_
O
.5
Parameter
Varied
Graphical
Representation
Size
PB Cost
PE Cost
% PB in Agglomerate)
Labor >
Equipment Cost )
Raw Materials Cost
Base
Value
20,000 tons/yr
40<£/lb
26<£/lb
3%
5 positions/shift
1.382 million dollars
864K dollars/yr
VALUE/BASE VALUE
Figure 37. Comparative Effect of Parameter Changes on
Operating Cost for the Encapsulation Process
(Nondimensionalized Values Plotted)
80
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140
oo
oc
o
cc.
UJ
a.
8
130
120
no
100
90
80
70
20 40 60 80 100 120 140
PLANT SIZE, K TONS DRY WASTE PER YEAR
160
180
200
Figure 38. Operating Cost as a Function of Plant Size
-------
also show that the plant should be sized between 20,000 tons per year and
60,000 tons per year. This range was arrived at because building a plant
capable of handling more than 60,000 tons per year will not significantly
reduce the cost of the process, and building a plant smaller than 20,000
tons per year causes a significant increase in cost.
Since the raw materials cost accounted for about 50% of the total
cost (base case), a study of cost as a function of the individual raw
material costs was undertaken. Preliminary results showed that the
acetone and nitrogen costs were negligible; hence, only the polyethylene
and polybutadiene costs were investigated. Results of the study are pre-
sented in Figures 39 and 40 for a process using 3% and 5% polybutadiene,
respectively. For the 3% polybutadiene process, changing the cost of
either material by the same amount changes the operating cost by nearly
the same amount (PE has slightly larger effect). In the case of a pro-
cess using 5% binder, however, the effect of changing the polybutadiene
price causes a greater change in the operating cost than does an equiv-
lent change in the polyethylene price.
Another point that was checked was the effect of the percent poly-
butadiene binder on the cost assuming a constant price (40<£/lb). Figure
41 presents the results which show that a decrease of 1% polybutadiene
binder (i.e., 3% to 2%) in the agglomerate causes about a $10 drop in the
process cost. Of course, for'lower priced material the effect is less.
The cost due to the labor force requirements was also studied. The
base case assumed five positions per shift and an average rate of $9.00/
hour. The results are shown in Figure 42 for a plant sizes of 20,000 tons
per year and 100,000 tons per year. In the first case a charge of one
position (equivalent to $95,000/yr) results in about a $7.25 change in
operating cost, but for the second case this causes only a $1.00 change
in operating cost. Even if the labor force is reduced by the same per-
centage, the effect is still greater for the smaller plant.
82
-------
ce
LU
a.
o
Q
I/O
O
O
13
a.
o
0
3% Polybutadiene Resin in Agglomerate
120
140
20 40 60 80 100
RAW MATERIAL COST, CENTS PER POUND
Figure 39. Operating Cost as a Function of Raw Material Costs
83
-------
o:
Q
a:
UJ
D-
co
a:
o
a
co
O
o
CD
a.
o
no
100
90
80 .
70
60
5% POLYBUTADIENE RESIN IN AGGLOMERATE
0 20 40 60 80 100 120
RAW MATERIAL COST, CENTS PER POUND
Figure 40. Operating Cost as a Function of Raw Material Costs
84
-------
no
ce.
a
a:
LU
o.
1/1
o
a
to
o
o
a.
o
70 '
60
SIZE = 20,000 TONS PER YEAR
0 12 34 56
% PB IN AGGLOMERATE
Figure 41. Operating Cost as a Function of % PB in Agglomerate
85
-------
90
80
a
o
Oi
LU
CL.
O
o
oo
O
O
LU
Q_
O
70
60
50
40
12
16
20
24
NUMBER OF POSITIONS PER SHIFT
Figure 42. Operating Cost as a Function of Labor Force
86
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Dewataring cost effects were studied as it was felt that not only
solid wastes but also sludges might be handled by this encapsulation pro-
cess. The literature indicated that the cost of dewatering tends to
range from 6 to 20 dollars per ton of dry waste (1); therefore, this
range was looked at and expanded. Since the dewatering in the literature
deals with nonhazardous sludges, the costs are probably lower than would
be encountered for handling sludges containing heavy metals. To fully
analyze the dewatering cost a process needs to be developed and costed
in a manner similar'to the procedure used in arriving at encapsulation
costs. The results presented in Figure 43 show that dewatering costs
could account for as much as 50% of the total cost. It should be pointed
out that the dewatering cost will be greatly dependent on the solids con-
tent; hence, streams containing high solids will cost less to dewater than
streams containing low solids.
The parametric studies pointed out that small changes in raw materials
cost (actual dollar values) have a significant effect'on the change in
operating cost. The size of the labor force needed will also have a
significant impact on the cost of the encapsulation process. Equipment
costs were not studied in depth since a substantial price reduction
(actual dollars) is required to substantially reduce the operating cost.
The area which appears to have the greatest effect on the operating cost
is raw materials. Not only the price, but also the amount of these ma-
terials required, has a significant effect on the overall cost. A decrease
in the binder content from 3% to 2% coupled with a price decrease of 10<£/
pound would lower the operating cost by about $12/ton dry waste. Therefore,
primary efforts to decrease cost should be focused on the raw materials with
secondary efforts aimed at decreasing equipment cost and labor force. The
general conclusions of the economics study are as follows:
Raw materials account for about 50% of the operating cost for
encapsulation.
Labor costs and factors associated with equipment cost each
account for about 25% of the operating costs.
87
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cc.
UJ
Q_
OO
o;
o
a
oo
o
o
160
150
140
130
120
110
100
90
80
70
60
10 20 30 40 50 60
DEWATERING COST, DOLLARS PER TON DSW
70
Figure 43. Operating Cost as a Function of Dewatering Costs
-------
Dewatering cost may be as high or higher than 50% of the
total processing cost.
An in-depth study of dewatering is required to determine
the order of magnitude of this cost.
Primary effort should focus on factors associated with raw
materials in lowering operating costs; secondary efforts
should be placed on labor and equipment cost.
The capacity of the plant should be between 20,000 and
60,000 tons dry waste per year. In this size range costs
do not vary significantly.
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7. IDENTIFICATION OF MANAGEABLE WASTES
The purpose of this work element is to provide guidelines relative to
employment of the TRW process for passivation of hazardous heavy metal con-
taining wastes. In addition, estimates are given of the amount of heavy
metals discarded by U.S. industry. Hazardous wastes are divided into three
divisions: the first defining wastes for which the TRW process may be
uniquely applicable; the second wherein higher passivation performance may
be realized; and third, areas of application which require precaution in
application of the TRW encapsulation method.
From the viewpoint of realizing high performance localization, certain
hazardous, difficult to manage wastes destined for disposal into the eco-
logical environment can be very effectively passivated, in our opinion, by
the TRW process. (See Section 8 for further discussion.) Other, less
hazardous, wastes currently passivated by incorporation in resin matrices
(inorganic or organic material matrices) may exhibit stability only in a
narrow range of environmental conditions. For such wastes, the TRW process,
in our opinion, can assure higher performance localization under a broader
range of exacting conditions than that of "matrix" passivation. Finally,
some wastes exist for which the TRW process may not be applicable; in these
cases, it may be necessary to test the process with respect to the specific
waste.
The identification of difficult to manage wastes which are expected
to be particularly applicable to disposal by the TRW process was related,
as follows, to constituents present in the wastes. These consituents de-
termine the suitability of passivation processes with respect to realizing
high performance waste localization.
The TRW process may be uniquely applicable to wastes con-
taining, for example, sodium antimonide, sodium metaarsenate,
sodium pyroarsenate, sodium arsenate fluoride, sodium chromate,
sodium cyanide, sodium cyanocuprate, sodium fluoantimonate,
sodium fluoberyllate, sodium fluoborate, sodium fluoride,
90
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sodium iodide, sodium plumbate, sodium selenate, sodium
selenide, sodium thiocyanate, sodium thioantimonate,
lithium antimonide, lithium orthoarsenate, lithium fluoride,
lithium iodide, lithium selenide, potassium antimonide,
potassium orthoarsenate, potassium orthoarsenite, potassium
cacodylate, potassium cadmium cyanide, potassium cynate,
potassium cyanide, potassium cyanocadmate, potassium
cyanocobaltate, potassium cyanocuprate, potassium cyano-
mercurate, potassium ferricyanide, potassium fluoberyllate,
potassium hexofluorophosphate, potassium lead chloride,
postassium magnesium selenate, potassium mercury tartrate,
potassium selenate, potassium selenite, potassium seleno-
cynate, potassium selenothionate, potassium sodium antimony
tartrate, potassium thioarsenate, potassium thioarsenite,
potassium thiocyanate, arsenic selenide, arsenic oxide,
beryllium selenate, cadmium selenate, copper triarsenide,
copper selenide, copper antimonide, lead orthoarsenate,
mercury oxide, selenium oxide.
t The TRW process may advance the range of stability of wastes
currently passivated in resin matrices containing, for ex-
ample, arsenic bromide, arsenic disulfide, arsenic penta-
sulfide, arsenic trisulfide, beryllium acetate, beryllium
bromide, beryllium fluoride, beryllium chloride, beryllium
sulfate, beryllium acetate, beryllium carbide, cadmium
pyrophosphate, cadmium metasilicate, cadmium sulfate, copper
tetraammine nitrate, copper carbonate, lead acetate, lead
bromide, lead chlorate, lead fluoride, lead phosphide,
mercury bromide, mercury fluoride, mercury iodide, selenium
chloride, selenium monobromide trichloride.
The TRW process as presently constituted was applied to
wastes free of mobile water and highly volatile compounds.
The presence of absorbed water and organic matter, however,
should not preclude the application of the process.
91
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Organic matter containing mercaptans may affect the extent
of resin reaction in agglomerate formation, however, it
is most unlikely that sufficient mercaptan will be present
to prevent rigidification of waste. This is due to the
high functionality of the agglomerate binding resin where-
in low extents of reaction will give rise to three
dimensional structures. In the event agglomeration does
not take place, flowers of sulfur in small quantities
admixed into the resin should assure rigidification.
Sulfur curing was not employed in this work because it
may, in our opinion, compromise ready demolding of the
agglomerate after its formation. Demolding is a de-
sirable property which facilitates waste passivation
processing. Encapsulation of the resin agglomerated
wastes, on the other hand, should not be effected by the
chemical composition of the waste
In the preparation of encapsulated specimens in the
laboratory, volatile matter in the agglomerate needed
to be excluded in order to carry out effective encapsu-
lation. Preparation of large, cost effective encapsu-
lated waste products, described in Section 6, should
not be sensitive to the presence of some volatile matter
in the agglomerate. Thermal energy required for carrying
out encapsulation heats only the extremities of the
agglomerate, thus volatile matter produced will condense
in the unheated bulk of the agglomerate.
Estimations of the quantity of heavy metals discarded by U.S. industry
as waste is provided here. These estimations were based upon extracts of
unpublished reports prepared in response to a program being carried out by
the Office of Solid Waste Management Programs, U.S. Environmental Protec-
tion Agency, concerning an assessment of industrial waste practices. This
program will provide reports reflecting waste generation and disposal
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practices by industry as given in Table 19. The finalized reports will
yield extensive information in respect to the nature and the amount of
heavy metal waste produced by U.S. industry. Unfortunately, chemical com-
positions were not given of the compounds containing heavy metal atoms.
Such information is desirable for assessing the utility and specificity
of the TRW Process with respect to specific wastes.
The following paragraphs provide information concerning heavy metal
wastes from industries designated by the paragraph titles:
7.1 METAL MINING
The wastes of metal mining usually consist of overburden, waste rock,
and tailing. These materials do not contain toxic materials concentration
greater than the land in which they are disposed. Thus they do not con-
tribute generally to the potential hazards.
Ore concentration, however, can give rise to "tailings" which may con-
tain toxic substances in higher concentrations than the land on which they
are disposed. Of particular concern is pyrite (FeS2) due to its formation
of sulfuric acid in the presence of air and water. The acid could then
leach toxic metals from the waste. Of further concern are tailings from
the uranium industry, (SIC 1094) the lead/zinc industry (SIC 1031), and
the copper industry (SIC 1021). These tailings contain the following
heavy metals: Copper, lead, zinc, cadmium, radium, arsenic, selenium and
beryllium. Adequate waste treatment and land-disposal methods for poten-
tially hazardous wastes, however, were reported to be available to the
metal mining companies.
7.2 INDUSTRIAL INORGANIC CHEMICALS
The nature and amount of heavy metal wastes stemming from the inorganic
chemical industry are given in Table 20. About 12000 metric tons (0.6 per-
cent of the total) go into secured landfill. On-site storage and disposal
such as deep welling, currently accounts for over 75% of the total waste
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TABLE 19. INDUSTRIES CURRENTLY UNDER STUDY
1. Industry: Metals Mining
SIC Codes: 1021; 1031; 1092; 1094; 1099
Contractor: Midwest Reserach Institute
Completion: February 1975
2. Industry: Industrial Inorganic Chemicals
SIC Codes: 281
Contractor: Versar, Inc.
Completion: November 1974
3. Industry: Pharmaceuticals
SIC Codes: 283
Contractor: A.D. Little, Inc.
Completion: February 1975
4. Industry: Paint and Allied Products
SIC Codes: 285
Contractor: WAPORA, Inc.
Completion: February 1975
5. Industry: Organic Chemicals, Pesticides, and Explosives
SIC Codes: 286, 2879; 2892
Contractor: TRW Systems Group
Completion: February 1975
6. Industry: Petroleum Refining
SIC Codes: 291
Contractor: Jacobs Engineering Company
Completion: December 1974
7. Industry: Primary Metals
SIC Codes: 331; 3321; 3322; 3324; 333; 3341; 3399
Contractor: Calspan Corporation
Completion: January 1975
8. Industry: Electroplating
SIC Codes: 3471
Contractor: Battelle Columbus Laboratories
Completion: February 1975
Industry: Primary and Storage Batteries
SIC Codes: 3691; 3692
Contractor: Versar, Inc.
Completion: November 1974
93
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TABLE 20. SUMMARY OF LAND DESTINED HAZARDOUS WASTES FROM INORGANIC
CHEMICAL INDUSTRY (SIC 281) (DRY BASIS)
Metric Tons/Year to Land Disposal
Current 1977 1983
SIC 2812 Hazardous Constituents (1) 7,000 7,500 4,200
Total Waste Stream 57,000 56,000 45,000
SIC 2813 Hazardous Constituents (2) 0 0 0
Total Waste Stream 00 0
SIC 2816 Hazardous Constituents (3) 4,700 5,800 6,900
Total Waste Stream 160,000 230,000 320,000
SIC 2819 Hazardous Constituents (4) 52,000 53,000 66,000
Total Waste Stream 1,800,000 2,000,000 2,400,000
SIC 281 Hazardous Constituents 64,000 66,000 77,000
Total Waste Stream 2,000,000 2,300,000 2,800,000
(1) From Alkalies and Chlorine Industry; asbestos, chlorinated
hydrocarbons, lead, mercury.
(2) From Industrial Gases Industry; no hazardous constituents.
(3) From Industrial Pigments Industry; antimony, arsenic;
cadmium, chromium, cyanide, lead, mercury, zinc.
(4) From Industrial Inorganic Chemicals; arsenic, fluoride,
chromium, nickel, phosphorus.
95
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generated by the industry. Since treatment/disposal costs were reported
to be a relatively low percentage of the product selling price, more ef-
fective means of waste localization may be employed with respect to im-
proving performance and, perhaps, without impacting adversly upon product
price.
7.3 PHARMACEUTICALS
Table 21 gives the nature and the amount of heavy metal wastes generated
by the pharmaceutical industry.
TABLE 21. ANNUAL HEAVY METAL WASTES GENERATED BY THE PHARMACUETICAL
INDUSTRY
Waste Type
Zinc
Arsenic
Chromium
Copper
Selenium
Mercury
Waste Lbs/year
5,000,000
1,000,000
50,000
10,000
400,000
1,500
Heavy Metal in Wastes Lbs/year
2,000,000
20,000
20,000
3,000
1,000
600
Source: ADL, Inc. Estimates
Most of the hazardous wastes are organic in nature and are disposed by
incineration. Heavy metal containing residues may not be readily recycle-
able economically, therefore localization is required for their passivation.
96
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7.4 PAINT AND ALLIED PRODUCTS
Hazardous wastes which could stem from the paint and allied products
industry contain arsenic, beryllium, cadmium, chromium, copper, lead,
mercury, selenium, zinc. The first eight elements are materials which EPA
believes, on the basis of initial analysis, to have the potential for pro-
ducing serious public health,and environmental problems. The contractor
added the following elements with toxic chemical potential: antimony,
barium, and cobalt. With respect to the above list of heavy metals no
plant surveyed was found to employ arsenic and beryllium.
7.5 ORGANIC CHEMICALS, PESTICIDES, AND EXPLOSIVES
No appreciable amount of heavy metal wastes was found to stem from
the organic chemicals industry.
7.6 PETROLEUM REFINING
Wastes generated from the petroleum refinery industry as sludges,
solids and slurries are estimated to be 1.3 million metric tons per year.
In 1977 and 1983 the projected estimates are 1.4 million and 1.5 million
metric tons per year, respectively. The proximate analysis of the aggre-
gate waste has a moisture content of 59%, an oil content of 8%, and an
ash content of about 33%.
The total amount of hazardous constituents is approximately 250
metric tons/year (dry basis). Chromium and zinc represent 62% of all
potentially hazardous constituents found in the refinery total. Copper,
nickel, vanadium, and lead are the next four highest constituents in terms
of total amounts of potentially hazardous waste representing 29%. These
four additions to chromium and zinc account for 90% of the total weight of
hazardous constituents.
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7.7 PRIMARY METALS
The principal potentially hazardous constituents found in primary and
secondary smelting residuals are heavy metals, including arsenic, cadmiura,
lead, zinc, copper, chromium, antimony, and nickel. Because of trace
amounts in the concentrates and ores from which the metals are recovered,
the primary base metal smelting and refining industries (i.e., lead,
copper, zinc, antimony, mercury, tungsten, and tin) produce a wider
variety of heavy metals in residues, including arsenic, cadmium, lead,
zinc, copper, antimony, nickel and mercury.
The predominant practices used in the primary and secondary non-ferrous
smelting and refining industries for disposal of residuals are lagooning
and open dumping. Slags and other solid residues are generally open dumped
on land. Scrubwater from wet emissions control and process wastewater with
or without lime treatment is generally routed to unlined settling pits or
to unlined lagoons. Settled sludge is often dredged from pits or lagoons
and stored or disposed of on land. Industries which produce relatively
small quantities of sludge will often leave sludges permanently in lagoons
The use of unlined settling pits and lagoons is the predominant practice.
Although the presence of potentially hazardous constituents in slags
sludges and dusts has been shown, it is generally not known if these
materials are leached in disposal environments. In the event that signifi-
cant leaching is demonstrated, a number of recommendations are made with
respect to practices for adequate health and environmental protection. It
is suspected that sludges and dusts may leach heavy metals and other
potentially hazardous constituents to a greater extent than most slags
because of fine particle size and consequent susceptibility to weathering
processes.
7.8 ELECTROPLATING
Table 22 provides an estimate of total national waste from electro-
plating and metal finishing.
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TABLE 22. ESTIMATED TOTAL NATIONAL WASTES FROM ELECTROPLATING
AND METAL FINISHING JOB SHOPS, METRIC TONS PER YEAR
(72 HOUR WEEK BASIS)
1975
Degreaser Sludge 5,579.69
Water Pollution Control Sludge 57,864.76
Other Solid Waste 118.348.27
Total 181,792.72
1977
Degreaser Sludge 5,579.69
Water Pollution Control Sludge 109,163.88
Other Solid Waste Tl8,348.27
Total 232,616.10
Metal hydroxides found in sludges are: Fe (OH)2, Cu (OH)2, Zn (OH)2>
Ni (OH)2, Al (OH)3, Cr (OH)3, Cd (OH)2> Sn (OH)2 and Pb (OH)2-
7.9 PRIMARY AND STORAGE BATTERIES
s
Large quantities of lead, cadmium, zinc, and mercury are used in
battery manufacture and thus appear in the wastes produced by the industry,
though they are present in only 5%-of the wastes destined for land disposal
and in low concentrations. The amounts of heavy metals which are reported
by the U.S. Bureau of Mines (1973) for battery production in the U.S. are
698,038 kkg lead (50% of U.S. consumption), 848.3 kkg cadmium (15% of U.S.
consumption), 408.2 kkg mercury (22% of U.S. consumption) and 27,210 kkg
zinc|(20% of U.S. consumption).
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The land destined wastes from the battery industry contain a small
percentage of heavy metals compared to the industry's total consumption.
Only 0.007% of the total lead used by these industries is lost as waste,
while 0.3% of the total cadmium, 0.5% of the total mercury, and 1.5% of
the total zinc are lost.
The storage battery industry (SIC 3691) currently disposes of 47.3
kkg of potentially hazardous constituents on land in a total waste stream
of 9,235 kkg consisting of water effluent treatment sludges and rejected
and scrap cells. Projections for 1977 for land disposal indicate that
these figures will grow to 467 kkg of hazardous constituents contained in
a total waste stream of 162,800 kkg. By 1983, land disposal of hazardous
wastes will increase to 625 kkg in a total waste stream of 207,700 kkg.
The greatest amount of wastes destined for land disposal from this
industry stems from lead-acid battery production. A large increase in
hazardous waste for 1977 and 1983 is'projected on the basis of future
wastewater treatment guidelines. These projections are based on infor-
mation obtained from industry on future growth of the industry along with
possible changes in the wastewater treatment area, which will affect the
amount of wastes destined for land.
The primary battery industry (SIC 3692) currently disposes of 448 kkg
of potentially hazardous constituents in a total waste stream of 1,202 kkg;
the waste consists primarily of rejected and scrap cells, together with
water effluent treatment sludges and furnace residues. By 1977, pro-
jections indicate that 514 kkg of hazardous constituents in a total waste
stream of 1,500 kkg will be destined for land. By 1983, projections indi-
cate that 502 kkg of hazardous constituents in a total waste stream of
1.350 kkg will be land disposed. The decrease of wastes going to land from
1977 to 1983 is due to projections concerning recovery of valuable scrap
from the waste stream and a projected decrease in hazardous wastes from
mercury cell production.
100
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The wastes from battery production are generally not water soluble,
and would normally have only minimal migration in a landfill environment.
However, solubility varies greatly with small changes in pH, and pH varies
in soils, groundwaters, and necessarily in landfill environments. For
this reason those wastes containing heavy metals in any form or concen-
tration have been considered potentially hazardous due to the possibility
of leaching into surface or groundwater.
The prevalent method of treatment and disposal for potentially hazard-
ous wastes from the storage batteries industry is land storage of waste-
water treatment sludges and reclaimation, where possible, of reusable
heavy metals such as lead, nickel and cadmium scrap. The best available
technology currently used for the wastes from this industry is a segregated
landfill equipped with leachate collection and treatment. Disposal in
secured landfills is considered an environmentally adequate level of tech-
nology for small volume wastes with a relatively large hazardous waste
content. Disposal of large volume sludges with a lower hazardous waste
content in approved disposal facilities, with leachate treatment and
monitoring, is also considered environmentally adequate.
For the primary batteries industry, the prevalent method of treatment
and disposal is in a simple landfill. The best available techno-
logy currently used for the wastes from this industry is segregated land-
fill equipped with leachate monitoring. Disposal in secured landfill is
considered an environmentally adequate technology for the small volume,
relatively high levels of hazardous wastes from this industry.
The cost of disposing of the small volume wastes in secured landfills
does not appear to have significant economic consequences to the industry.
The only area where relatively large costs are involved is the disposal of
calcium sulfate water treatment sludges containing lead from the lead-acid
storage battery industry.
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8. FURTHER OBSERVATIONS
This work showed that the TRW process for passivation of dry, heavy
metal waste may be employed generally without need to tailor the process
with respect to the nature of the waste. When the passivated wastes were
subjected to a broad range of exacting leaching solutions, all the heavy
metal wastes investigated in this study exhibited high performance local-
ization. Similar results should be expected for other heavy metal wastes
as wel1.
Certain heavy metal wastes, in our opinion, can not be successfully
passivated by means other than the TRW process. Such wastes would contain,
or could yield with certain compounds, heavy metal atoms in the anionic
moiety of salt compounds wherein the counter ions are alkali metals. Such
compounds are usually very soluble in water. In the anion, heavy metals
usually exist in chemical conjunction with other atoms as coordination com-
plexes, thereby realizing electron saturation of their electron orbitals.
Consequentially, it is not possible to fashion the insoluble coordination
complexes with selected resins that would give rise to stable localization
of heavy metals in resin matrices without prior chemical treatment of the
contaminants. The effectiveness of most current passivation processes
in this respect may be questionable because they depend upon the forma-
tion of such complexes.
Furthermore, the TRW process may be uniquely applicable to other types
of wastes. Such wastes would contain water insoluble heavy metal salt and
covalent compounds. Although these wastes resist heavy metal dispersion
into the ecology by dissolution, they may be subject to such dispersion
in particulate form by ecological forces. Encapsulation, in our opinion,
may be the most effective means for precluding such occurrences.
Resins can be tailored, however, to passivate heavy metals when such
metals exist as cations of salt compounds. Heavy metal cations in many
such cases contain electron orbitals which give rise to stable coordination
102
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complexes with certain resins, e.g., polysilicic acids. Yet even here
high performance localization may exist only in a narrow range of environ-
mental chemical conditions.
Although it would be desirable to rate heavy metal wastes with respect
to their receptibility to passivation by different passivation processes,
the lack of knowledge concerning the nature of the heavy metal compounds
in the waste, and the complexity of the wastes per se, percludes such a
rating. In our opinion, however, all heavy metal compounds without respect
to their chemical state, with the possible exception of those yielding
gaseous compounds, would be effectively localized by the TRW process.
Nevertheless, certain wastes may be more suitable to localization by other
means when relating heavy metal waste passivation to a cost-performance
framework.
The mechanics of processing and the materials required determine the
cost of products stemming from the TRW process. An estimate of $91 a ton
was provided. This estimate was based upon processing and materials in a
large scale operation that follows the operation as carried out in the
laboratory. But in this work the laboratory operation was directed to
fashioning specimens for performance evaluations, and not to determining
means for reducing costs. Yet it is meaningful to estimate the initial cost
in this fashion because it relates cost to products whose performance have
been characterized. Additional work should be directed to decipher means
for reducing costs, and this work will, in our opinion, yield meaningful
economic gain while maintaining production of high performance products.
Agglomeration, for example, can be effected by thermally hardening
the resin coated waste merely at the faces of the agglomerate rather than
throughout. Thus, partial hardening, which can occur in the mold, may be
sufficient to carry out subsequent, effective resin jacketing of the
agglomerate. Wastes with volatile matter will be more readily processable
because the volatiles would readily condense in the innards of the agglom-
erate rather than being vented into the atmosphere. The ovens shown in
the work for hardening agglomerates throughout could be eliminated.
103
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The commercial resins employed in this work are resins of quality in
advance of that required for fashioning high performance products. Crude
polybutadiene resin for making agglomerates, in our opinion, are sufficient;
and the higher cost, electrical grade, commercial resin, employed here for
convenience sake, is not necessary. The use of lower grade resin should
make a significant impact on price due to the greater costs associated
with production of electrical grade resins. Lower grades of commercial
polyethylene may also be employed for jacketing agglomerates, although
greater care may be required when compromising the resin quality of
polyethylene than that of polybutadiene. However, low cost filler and resin
extenders may be employed for reducing cost without sacrificing product
performance.
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APPENDIX A*
*
From work performed under Contract No. 68-03-0089
A-l
-------
A-l. ORGANIC RESIN ENCAPSULATION
INTRODUCTION
The purpose of passivation is to limit the release of hazardous waste
components to acceptable levels. Since water is usually both the
solvent and the transport medium for wastes disposed to the land, the
most effective techniques for effecting passivation are expected to be
those which best isolate the wastes from water. Plastics have
particular appeal for this application because of the well known
aversion most plastic systems have for water.
*
Early efforts with plastic systems involved mixing the waste materials
with molten plastics which solidify upon cooling. The high viscosity
of the molten plastics generally limited the quantity of waste that
could be loaded into the plastic matrix. The incorporation method
was also limited by the inability of the matrix to isolate the waste
from the environment. A highly loaded matrix exposed some waste at
the surface of the block directly to the environment where it could be
leached. Leaching exposed further surface area and so forth.
The TRW organic cementation process differs considerably from the simple
incorporation or one step techniques tested previously. The TRW technique
is a "two step" process which involves mixing the waste with an unfinished
prepolymer, curing the polymer, to a finished plastic, then jacketing the
resulting agglomerate in order to isolate it from the environment. This
procedure uses significantly less resin than the previous technology (95+%
loadings as opposed to 30% loadings) and furthermore, the hazardous
materials are better isolated from the environment by a uniform coating
rather than the random packing typical of the "one step" method.
The organic cementation process involves three.basic operations as
shown in .Figure A-l: (1) coating the solid particulates with a pre-
polymer dissolved in an organic solvent, (2) compacting the particulate/
prepolymer system into a block by application of pressure and curing
(thermosetting) the thermoset resin with heat, and (3) jacketing
A-2
-------
sludge
w
dewater
participate
^-
- .1 ^
resin
coated
parti cul ate
i
GO
solvent
evaporation
fc^
parti cul ate/
resin
agglomerate
compacting
by thermo-
setting
k-
cemented
waste
block
stabilized
waste
disposal
Figure A-l. Schematics of Organic Cementation Process for Stabilization of Hazardous Wastes
-------
(encapsulation) the resin cemented waste block with coating resin by
fusion.
In the remainder of this section the various process studies made during
this phase on the organic cementation technique are discussed. The selec-
tion of resins for the matrix and jacket is described. The experimental
efforts on both the core and jacketing are also discussed in the following:
SELECTION OF ORGANIC RESINS FOR AGGLOMERATION OF SOLID WASTE PARTICLES
In the selection of resins suitable for agglomeration of solid particulates
the following criteria were applied:
High loading ability, i.e., small amounts of resin must be
capable of agglomerating and cementing large amounts of waste
particulates.
Chemical stability of the agglomerate waste.
Ability to readily wet solid waste particulate.
Easy and rapid formation of resin coated waste agglomerate
for a wide variety of waste materials.
Uniform distribution of resin in the agglomerate.
High heat distortion temperature (HOT) to allow for wide selection
of resin for jacketing; fusion of coating resin to the cemented
waste core should not cause any dimensional distortion of the
compacted core block.
Low cost.
Stability under normal conditions: no special precautions
for resin storage.
Satisfactory fluidity of waste/resin agglomerate particulates
for fast and thorough filling of mold for compacting by
thermosetting.
Long "pot life" to allow the processing time to vary widely.
Since they can be formulated to meet all of the above criteria hydro-
carbon resin systems are excellent binders for passivation of heavy metal
compounds by agglomeration and thermosetting cementation. They
A-4
-------
are non-polar and provide a resinous matrix for embedding the waste
participates. The heavy metal salts are not soluble in the hydro-
carbon resins and consequently they affect neither their rhelogical
properties nor the chemical reactions which occur during thermosetting.
Within the general category of hydrocarbon resin systems certain of
the polybutadiene resins appear particularly attractive for cementation
of hazardous waste particulates. Butadiene, the monomer from which
the resins are synthesized, is a major product of the petrochemical
industry. It is readily available and relatively low in cost and is
expected to remain so despite the shortages of petroleum. Butadiene
.is a major component of rubber tires and therefore must remain a
commodity chemical.
The monomer polymerizes to yield polybutadienes of various stereo
configurations depending upon the conditions of polymerization.
Polybutadienes of certain configurations were found to be unsuitable
for use as agglomerate binders. The unstabilized high 1,4 cis, and
high 1,4 cis/trans materials were found to be susceptible to oxidation
under atmospheric conditions.
The high 1,2 stereoregular, and high 1,4 trans are solids melting at
high temperature. The polybutadienes found to be particularly applic-
able for agglomerate formation were those with stereoconfigurations
high in 1,2 atactic. These materials are liquid and they polymerize
easily because of the high content of unsaturated bonds.
Atactic 1,2 polybutadiene resins without chemically functional grouos can
be synthesized as polymers of relatively low molecular weight, i.e., about
1000 to 2000. They are quite fluid when heated to temperatures of about
320°F, the temperature required to bring about rapid thermosetting of the
resin. This fluid state, unfortunately, contributes to resin drainage in
the course of transition of the compacted waste to the agglomerated state.
Consequentially, the resulting agglomerates may not exhibit uniform dis-
tribution of waste in cross section.
A-5
-------
Two methods may be used to decrease the fluidity of the polybutadiene
resins during thermosetting. One is to utilize polybutadienes of
substantially greater molecular weights. The other is to utilize
polybutadienes of similar molecular weights which contain chemically
functional terminal groups. The latter approach was selected in this
work since it combines high fluidity at the time of initial resin
coating of the waste with reduced fluidity during thermosetting.
The chemically functional polybutadienes selected for this work were
those containing carboxyl groups. Hydroxyl groups and mercapto groups
were also considered. The advantage of the carboxyl groups was that
they are readily attached, react with epoxide resins to reduce fluidity
during thermoset and are stable in air. The mercapto groups react with
epoxide resins but they are labile under atmospheric conditions. The
hydroxyl groups are oxidatively stable, but they do not react readily
with the epoxide resins. Hence, both mercapto and hydroxyl groups were
discounted in this work.
Epoxide resin (for viscosity control) was added to a solution of carboxyl-
terminated polybutadiene containing a small amount of catalyst peroxide
for use in resin thermosetting. A small amount of organic base was
also added in order to promote the desired linear extension of the
polybutadienes through the carboxyl-epoxy reaction. This solution was
found to have excellent shelf stability. The resin coated wastes were
made by solution wetting of the waste, followed by evaporation of the
solvent. They were also found to have excellent shelf stability and
excellent "pot life" so long as the material was not exposed to sunlight
for prolonged periods.
SELECTION OF ORGANIC RESINS FOR JACKETING
Jacketing or encapsulation of the agglomerated waste/resin core with
a layer of coating resin is designed to separate the core content from
environmental forces which might disperse the toxic components into
the environment. The resins selected for jacketing must meet certain
requirements; the most important are:
A-6
-------
Resistance to water
Chemical stability
Thermal and mechanical stability
Good adhesion to the jacketed waste core
Easy processability onto the surface of the core
Low cost
t Non-biodegradable
Resistant to weathering
Three resins meeting the above criteria were utilized in the jacketing
experiments:
Polyvinyl chloride plastisols (PVC) are liquid and may be
readily fashioned into thermally stable material by
heating.
t Polybutadiene modified epoxides produced by Goodrich Rubber
Company. Preliminary experiments indicated that upon
altering of the rheological properties of these resins
good coatings may be obtained.
Polyethylene resins treated with polybutadiene resin
(PE/PB). The polyethylene particles coated with functional
polybutadiene resin yielded a more homogeneous coating
which exhibited upgraded thermal stability, mechanical
strength and diffusion resistance. The combination of
chemically functional polybutadiene with polyethylene is a
unique and novel plastic system developed during this work.
EXPERIMENTAL ORGANIC CEMENTATION STUDIES
Experimental Studies on Compacting of Solid Particulates into Blocks
by Cementation with Resins
Feasibility studies on the applicability of the organic resins for cemen-
tation of solid particles were usually performed using sodium chloride
as a waste simulant. The hazardous waste simulant used for the inorganic
testing was also used for some tests. The procedure for agglomeration
of solid particles was as follows:
A-7
-------
the constituents of the cementing resin were dissolved in a solvent,
usually acetone (the amount of solvent by volume was about 4 times the
volume of resin). The solid particles were mixed with the resin solu-
tion in a Hobart mixer. After intimate blending the solvent (acetone)
was evaporated with gentle heating leaving behind resin covered
agglomerates of solid particles. These agglomerates were transferred
into detachable rectangular aluminum molds. There, the agglomerate was
squeezed with a plunger'under low pressure, the plunger was removed
and the agglomerate in the mold was heated to 350°F for 30 minutes.
The agglomerate consolidated into a block of cemented solids due to
thermosetting of the resin. After removal from the mold the warm
block was ready for jacketing.
The various organic cementation experiments are summarized in Table A-l.
Various resin systems were formulated and applied to the test solids.
As shown in the result summary the formulations were applied in varying
proportions to the solids. Since limiting the amount of resin while
achieving satisfactory performance would keep costs down, the studies
were concentrated in the range of 93 to 99 percent solids excluding
solvent. For example, in experiment 1 five different solids loadings
were examined over the range from 95 percent solids (5 percent resin)
to 99 percent solids (1 percent resin).
An interesting and important feature of the solids/resin systems is
the free-flowing consistency of the resin coated solid particles (Figure
A-2). This characteristic allows for fast and uniform filling of the mold.
The cemented block, however, is a very stable structure (Figure A-3).
Experimental Studies on Jacketing Cemented Blocks With Organic Resins
Jacketing with polyvinyl chloride plastisol: in general, the jacketing
was performed using commercial polyvinyl chloride plastisol in dioctyl
phthalate (OOP) solution, (Brand PK 5581A*). For a coating thickness of
1/8 inch the curing conditions are 350°F for a half-hour. Thicker coatings
were cured at 400°F for a half-hour.
*Product of Chemical Product Corporation, Western Division, Burbank, California.
A-8
-------
TABLE A-l. ORGANIC CEMENTATION EXPERIMENTAL RESULTS
Exp.#
1
2
3
4
5
Resin Formulation
Carboxyl terminated 1 ,2 polybutadiene
MW ^1000 ("Hystl" C-1000)3
Epoxy resin (Epon 828}
Dicumyl peroxide (DI-Cup R)c
Benzyl dimethyl ami ne (BDMA)
Hydroxyl terminated polybutadiene
"Hystl" G2000
pV-diphenylmethane dlisocyanate
(DDI)d
Trlethylene diamine (TEDA)
Dicumyl peroxide (Di-Cup R)
Polybutadiene ARCO
Toluene diisocyanate (TOI)
Dicumyl peroxide (Di-Cup R)
Polybutadiene "Hystl" G2000
Toluene diisocyanate (TDI)
Dicumyl peroxide (Di-Cup R)
Carboxyl terminated 1,2 polybuta-
diene MW 1000 "Hystl"
C1000
Epoxy resin - Epon 828
Dicumyl peroxide (Di-Cup R)
Benzyl dijpetbylanrine . (BJ3MA)
arts by
Weight
100
21
5.1
0.6
100
34
0.135
5.36
100
7.0
1.1
100
7.05
1.00
100
21
5.1
0.6
Cemented
Material
sodium
chloride
sodium
chloride
sodium
chloride
sodium
chloride
solid
waste
Percent
of Resin
1
2
3
4
5
2
3
4
5
1
2
3
4
5
1
2
5
7
Process
Conditions
350°F
30 min
200 °F
30 min
and
350°
1 hr
350°F
30 min
350°F
350°F
30 min
Results
Weak, brittle
Selfsustaining
Good
Good
Good
Selfsustaining
Good
Good
Good
Brittle
Selfsustaining
Good
Good
Good
Block fell apart
Block fell apart
Good
Good
Distributed by Dynachem Corp., Santa Fe Springs, California
Bisphenol A - Epichlorohydrin, produced by Shell Chemical Corp.
Hercules Inc., Chemical Dept.
General Mills Chemical Co. or Mobay Chemical Corp.
-------
Figure A-2. Solid Waste Particles Coated with Polybutadiene Resin
Figure A-3. Solid Waste Specimens Cemented with PB Resin: Left Uncoated;
Right Coated with PVC
A-10
-------
Agglomerated blocks were jacketed by placing them in a metal mold and
pouring resin into the annul us. The jacket was fashioned in a two-
stage operation; in the first stage approximately 5/6 of the surface
area was covered. The resulting partially coated block rested upon the
jacketed surface while additional resin was thermally fused onto the
uncoated area. The two-stage operation allowed venting of any residual
volatiles that may be present in the block prior to the completion of
the jacketing procedure. The seam at the juncture contact of the first
and second stage jacketing was found to be tough and flaw-free. Such
results were expected because usually a given resin adheres to itself.
The blocks jacketed with PVC plastisols were found to demold easily.
No sticking or crumbling was observed. A freshly removed block and
its mold are shown in Figure A-4.
A cross section of a jacketed block, shown in Figure A-5, exhibits the
interface between the jacket and the agglomerate. The jacketing resins
partially penetrated into the agglomerate. Mechanical locks were
formed between the jacket and the agglomerate.
Figure A-6 shows cemented sodium chloride blocks jacketed with PVC resin
before and after application of a compression stress of about 1000 psi.
Although yielding in accommodation to the highly distorted cemented
block, the jacket did not undergo break or rupture.
Jacketing with polybutadiene/epoxide resins: Goodrich Chemical resins
consisting of polybutadiene treated epoxides were evaluated as jacketing
resins. These resins yield tough flexible products. The presence of
polybutadiene in their compositions imparts desirable chemical as well
as mechanical locking of jackets onto the surfaces of the agglomerated
wastes. The properties of the jacket can be readily varied through
judicious formulation of Goodrich resin compositions. In this work,
the Goodrich resins became quite fluid at the jacketing fusion temp-
erature and penetrated appreciably into the body of the salt-containing
agglomerate. They did not yield "neat" resin jackets. It is expected
that this could be controlled given further study.
A-ll
-------
Figure A-4. Mold and Freshly Removed Waste Block
Figure A-5. Interface of Jacket and Block Showing Partial
Penetration of Plastic Jacket into the Aggregate Block
A-12
-------
Figure A-6. Dimensional Distortion of Jacketed Agglomerates
Under High Unidirectional Mechanical Loads
A-13
-------
Jacketing with polyethylene resins: a thermoplastic resin, polyethylene,
was investigated for use as a jacketing material. Powdered polyethylene
sold by U.S.I, under the trade name Petrothene was used in the experimenta-
tion.
The powdered thermoplastic was tamped into the annul us between the
block and the metallic mold. Simple application of heat was found not
to cause intimate knitting of the powdered resin into a homogeneous
jacket. Consequently, a metallic tube was machined and inserted into
the annul us. Mechanical pressure was applied by this tube during heat-
ing of the resin yielding homogeneous jackets.
The final application of the thermoplastic resin in the two-stage
jacketing procedure was accomplished by thermally fusing additional
resin while cooling the other surfaces onto the agglomerate. Mechanical
pressure was again applied through a metal rod. A product stemming
from these operations is shown on the left side of Figure A-7.
The purpose of modifying the polyethylene with polybutadiene was to
advance the dimensional stability of polyethylene at elevated temperatures.
In order to realize tough, homogeneous, high performance products,
various polybutadiene-polyethylene formulations were investigated. The
composition shown in Table A-2 provided the most satisfactory results.
The modification of polyethylene with polybutadiene resin was per-
formed in acetone solution. Liquid polybutadiene resin was dissolved
in acetone. Polyethylene powder and other additives were added and
the composition was mixed. The acetone was evaporated. The polyethylene
powder coated with polybutadiene resin was compacted and fused under
pressure at 320°F onto the cemented solid block. The procedure assured
chemical as well as physical bonding of the jacketing resin with the
jacketed core. The jacketing composition maintained rigidity to 350°F
(the highest temperature tested) after fusion. At this temperature
unmodified polyethylene was found to flow as readily as a molten candle
wax. Excellent protective jackets were obtained in this way. A
specimen jacketed with polyethylene resin modified with polybutadiene
is shown on the right hand side of Figure A-7.
A-14
-------
Figure A-7. Polyethylene Jacketed Agglomerated Solids,
Left: Polyethylene Jacket. Right: Poly-
butadiene Modified Polyethylene Jacket.
A-15
-------
TABLE A-2. POLYBUTADIENE-POLYETHYLENE COMPOSITION
Constituents
Parts by
Weight
Carboxyl terminated 1,2 polybutadiene MW 1000
Epoxy resin - Epon 828
Dicumyl peroxide - Di-cup R
Benzyldimethylamine (BDMA)
Polyethylene - petrothene
100
21
5
0.6
570
While the coating on the right has a milk white, waxy appearance, the
one on the left is translucent. This effect probably stems from the
loss of polyethylene crystal!inity due to the presence of the thermoset
polybutadiene within the resin composition.
A-16
-------
A-2. ENVIRONMENTAL TESTING
Cementation and encapsulation of hazardous wastes prior to ultimate
disposal is designed to prevent or limit the dissipation of toxic elements
or their compounds into the environment for an indefinite period. In order
to anticipate the behavior of the cemented and coated hazardous solid
wastes and sludges in ultimate disposal environments, laboratory pre-
pared specimens were subjected to a series of tests. The test program
was designed to provide preliminary data as to the expected behavior of
the encapsulated wastes when subjected to environmental stress. Of par-
ticular interest was the ability of the encapsulated material to resist
mechanical attack, such as, crushing and attack by aqueous solutions.
Major stress was placed on the qualitative behavior of the systems there-
fore, quantitative modelling of the results was not attempted. The
chemical analysis were designed to detect the ions of interest in the 1 ppm
regime. This corresponds to losses of mass to the cemented blocks of the
order of one-thousandth of a gram. Since the experiments are not directly
correlated to actual environments no conclusions can be drawn as to
toxicity implications. x
Mechanical Testing: the mechanical testing of cemented uncoated and
coated specimens included the determination of: (a) bulk density, (b)
surface hardness, and (c) compression strength. The bulk density was
determined by dividing the weight of the specimens by their bulk volume.
The surface hardness was determined using Type D durometer, Pandux, Model
307 which conforms to ASTM D 1484 and ASTM D 1706.* The compression
strength was determined on the testing machine "Cal-Tester."**
Visual Observation: the visual observation of the uncoated and coated
specimens included examination under the microscope of the specimens
*
Produced by Pacific Transducer Corporation, Los Angeles, California.
**
Produced by Pacific Scientific Company, Anaheim, California.
A-17
-------
before and after leaching. Particular emphasis was placed on the interface
boundary between cemented waste specimens and coating. For this purpose
the coated specimens were crosscut after leaching.
Leaching Experiments; the leaching of each specimen was conducted in 750
ml of aqueous solution at room temperature. The solutions were agitated
mildly twice a day and prior to withdrawing of samples in order to eli-
minate concentration gradients. Accidental contamination of the leaching
solutions was prevented by wrapping the tops of the beakers with plastics.
The following leaching solutions were used:
Distilled water
Saturated carbonic acid; COp bubbling at a rate about
60 ml/min. Approximate pH <3.8 - 4.0.
0.1M sodium sesquicarbonate solution (Na2C03/NaHC03).
Approximate pH ^10.1.
t Landfill leachate simulant having the following composition:
Sodium acetate 4.0 g/1
Potassium acetate 3.5 g/1
Ammonium acetate 3.0 g/1
Calcium acetate 30.0 g/1
Magnesium acetate 3.0 g/1
Ferric chloride 3.0 g/1
Sodium nitrate 0.1 g/1
Tannic acid 2.0 g/1
Glucose 2.0 g/1
Leachate Analysis: the leachates of the mainstream of uncoated and coated
specimens were analyzed after 1, 2, 4, 8, 15, 22, 30 and 60 days of leaching.
A-18
-------
The physico-chemical testing of the leachate included the determination of
pH and the determination of the specific conductance. Chemical analyses
determined the concentration of the toxic elements: As, Hg, Se, Cd,
Cr, Pb for those samples containing these elements or the concentra-
tion of Na for the cemented sodium chloride compacts.
The analytical procedure consisted of the following steps: 1) all solu-
tions were mechanically mixed prior to removal of a 25 ml sample, 2)
this 25 ml was then replaced with de-ionized water, the pipet rinsed and
the next sample taken, and 3) one ml of concentrated HN03 was added to
each solution as a preservative and in addition all samples were refrigerat-
ed if there was a significant .time delay between sampling and analysis.
The elemental composition was determined by atomic absorption (AA). The
operating parameters are summarized in Table A-3. AA standards were made
using the neat extraction solutions. This was done to minimize any in-
herent magnification or suppression of the analytical signal due to matrix
effects.
TABLE A-3. ATOMIC ABSORPTION OPERATING PARAMETERS
Element
Na
Hg
As
Se
Cr
Cd
. Pb
Flame
Conditions
Air-acetylene
Air-hydrogen
Argon-hydrogen
Argon-hydrogen
Air-acetylene
Air-acetylene
Air-acetylene
Analytical
Wavelength A
'8890
2536
1937
1960
3529
2288
2833
Slit
Width A
4
10
4
10
4
4
4
Lower Limit
of Detection (ppm)
0.01
5.0a
0.3
0.5
0.06
0.02
0.3
By using a flameless technique this value can be reduced to 0.01 ppm.
However, the time required for the analysis is significantly higher.
A-19
-------
ENVIRONMENTAL TESTING OF ORGANIC CEMENT SAMPLES
The following 2x2x2 inch specimens were used in environmental testing:
t Sodium chloride cemented with 2% by weight of
polybutadiene resin.
t Sodium chloride cemented with 3% by weight of
polybutadiene resin.
t Sodium chloride cemented with 4% by weight of
polybutadiene resin.
t Sodium chloride cemented with 5% by weight of
polybutadiene resin.
Sodium chloride cemented with 5$ by weight of
polybutadiene resin and coated with polyvinyl
chloride plastisol.
Hazardous simulant cemented with 7% by weight of
polybutadien resin.
Hazardous simulant cemented with 7% by weight of
polybutadiene resin and coated with polyvinyl
chloride plastisol.
t Sodium chloride cemented with 5% by weight of
polybutadiene resin and coated with polyethylene/
polybutadiene coat.
The sample preparation followed the methodology described in Section 2.
A-20
-------
Testing of Sodium Chloride Compacts Cemented With Polybutadiene Resin
Table A-4 presents the mechanical properties of uncoated sodium chloride
compacts cemented with different amounts of PR resin. The data refer to
the specimens not subjected to leaching. The compression strength and
hardness of these specimens was very good. After leaching of parallel speci-
mens for 60 days in water they lost about 70% of their sodium chloride con-
tent, became lighter than water and floated on it. The concentration of
sodium chloride in water was about 18%, i.e., approximately 50% of the
saturation value. After removal from the leaching solution the specimens
appeared very soft. The water, which replaced the sodium chloride at leach-
ing, could be squeezed out. No mechanical testing was possible on these
specimens at this stage.
Table A-5 presents the mechanical properties of sodium chloride compacts
cemented with 5% PB resin and PVC coated following removal from leachinq
solution. The compression strength of the specimen coated with oolyvinyl
chloride after leaching is satisfactory. A parallel specimen before leaching
exhibited compression strength 714 psi, i.e., 2-1/2 times greater. The
compression strength of the PE/PB coated specimen was excellent before and
after leaching, in excess of the range of the testing machine (5000 Ib)
which corresponds to about 900 psi for the size of this specimen. No
mechanical deterioration of any kind was observed on the coated specimens
during and after leaching, however small amounts of water were soaked through
or into the coating. This gain of weight was about 1.46% for specimens
coated with PVC after 60 days of exposure to solution and about 0.60% for
specimen coated with PE/PB after 30 days of exposure to leaching solution.
Figure A-8 presents the cross section of a sodium chloride specimen cemented
with 5% PB resin and coated with PE/PB coat after it has been leached a dense
and strong coating encompasses the cemented sodium chloride core.
Table A-6 presents the recorded changes of pH, electrical conductance and
concentration of sodium in the solution during the entire leaching period.
From the uncoated specimens sodium chloride diffused into the solution very
quickly, but from the coated specimens very slowly. The PE/PR coating was
superior to the PVC coating in preventing the diffusion of sodium chloride.
A-21
-------
TABLE A-4. MECHANICAL PROPERTIES OF SODIUM CHLORIDE COMPACTS CEMENTED
WITH POLYBUTADIENE RESIN, UNCOATED, BEFORE LEACHING*
Exp.
No.
1
2
3
4
Specimen Designation
Sodium chloride cemented
with 2% PB resin, uncoated
Sodium chloride cemented
with 3% PB resin, uncoated
Sodium chloride cemented
with 4% PB resin, uncoated
Sodium chloride cemented
with 5% PB resin, uncoated
Mechanical Properties
Hardness
45
57
59
60
Compression
Strength
psi
420
1230
1020
975
Bulk
Density
g/cm3
1.34
1.40
1.40
1.37
After leaching in water the specimens became soft and spongy and
no measurements were possible.
TABLE A-5. MECHANICAL PROPERTIES OF SODIUM CHLORIDE SPECIMENS CEMENTED
WITH POLYBUTADIENE RESIN AND COATED, AFTER LEACHING IN WATER
Exp.
No.
5
30
Specimen Designation
Sodium chloride cemented
with 5% PB resin and coated
with PVC
Sodium chloride cemented
with 5% PB resin and coated
with PE/PB system
Mechanical Properties
Hardness
55
30
Compression
Strength
psi
291 a
»900b
Bulk
Density
g/crn^
1.38
1.36
Parallel specimen before leaching exhibited compression strength 714
psi, bulk density 1.24 g/cm3 and hardness 55.
Before and after leaching the compression strength of this specimen
exceeded the range of the testing machine, i.e., about 900 psi for
its size.
A-22
-------
TABLE A-6. pH, ELECTRICAL CONDUCTANCE AND CONCENTRATION OF SODIUM IN WATER DURING
LEACHING OF SODIUM CHLORIDE SPECIMENS CEMENTED WITH POLYBUTADIENE RESIN (PB)
Exp.
No.
1
2
3
4
5
30
Specimen Designation
Sodium chloride cemented with
2% PB uncoated
Sodium chloride cemented with
3% PB uncoated
Sodium chloride cement with
4% PB uncoated
Sodium chloride cemented with
5% PB uncoated
Sodium chloride cemented with
5% PB and coated with PVC
Sodium chloride cemented with
S% PB and coated with PE/PB
system
Property
pH
x umhos/cm
Cone Na ppm
PH
x umhos/cm
Cone Na ppm
PH
X ymhos/cm
Cone Na ppm
pH
x pmhos/cm
Cone Na ppm
pH
x pmhos/cm
Cone Na ppm
PH
x ymhos/cm
Cone Na ppm
Days of Leaching
0
6.3
13.2
6.3
13.2
6.3
13.2
6.3
13.2
6.3
13.2
6.3
13.2
1
8.5 ,
2.5 x 10J
20300
9-5
80 x 103
11400
9-8
80 x 103
11400
9'6 *
9.4 x 103
11600
6.6
310
70
6.8
0.19
2
X
X
20700
X
X
13200
X
X
12900
X
X
12500
X
X
90
X
X
X
4
9.5 ,
141 x 10J
24700
9.4
133 x 103
14900
9-1 ,
136 x 103
15200
9-5 ,
164 x 103
23600
6.5
640
152
X
X
X
8
9J 7
169 x 103
29200
9.0
113 x 103
15100
8.8
169 x 103
22600
8.9
160 x 103
29300
6.3
1.1 x 103
154
5.6
141
4.25
15
9.0
179 x 103
30100
9.0
141 x 103
19100
9.1
179 x 103
34400
9.2
160 x 103
29800
6.8
1.9 x 103
216
5.6
94
5.00
22
9-0
179 x 103
31360
8.8
151 x 103
18700
8.9
188 x 103
35100
8.9
169 x 103
30000
6.3
2.8 x 103
302
X
X
X
30
8.6
188 x 103
32800
8.7
151 x 103
30400
8.9
113 x 103
39800
8.8
169 x 103
30200
9.5
4.7 x 103
540
4.7
46
5.10
60
8.8
94 x 103
54300
8.6
56 x 103
39800
8.6
66 x 103
68400
8.9
103 x 103
35300
8.5
6.6 x 103
760
ro
GO
-------
Figure A-8. interface Boundary Between Cemented Sodium Chloride
Compact and PE/PB Coat. (Magnification 4X)
The solutions resulting from leaching the uncoated specimens became alkaline.
This may be the result of a faster diffusion rate for sodium ion than for
chloride ion, there may be some chloride retention capacity of the cementing
PB resin. After about 4 days of leaching, the pH of the solution, which
exceeded 9, started to drop slowly. The solution resulting from leaching
the specimen coated with PVC followed generally the same pattern with
regard to the change of pH, but it took about a month to reach the pH level
of 9, undoubtedly due to the reduced diffusion rate through the coating
barrier. The change of pH of the solution resulting from leaching the
specimen coated with PE/PB system was quite different, after few days of
leaching the pH shifted in the acidic direction.
The electrical conductance of the solutions grew rapidly at the beginning
of the leaching. After some time the conductance leveled off and even
started to drop*
A-24
-------
Table A-7 presents the calculated diffusion rates of sodium ions into the
2
solution (grams/day/m ) for different time intervals. For uncoated
specimens the initial diffusion rate through the surface varied between
2
500 and 1000 grams/day/m at the beginning and dropped to the value below
2
50 grams/day/m after 30 days. The diffusion rate of sodium through the
applied coatings were negligible. Particularly effective was the PE/PB
coat. The initial diffusion rate of sodium ions through it was about
2
lg/day/m .
Testing of Hazardous Simulant Compacts Cemented with Polybutadiene Resin
Table A-8 presents the mechanical properties of hazardous simulant speci-
mens cemented with 7% polybutadiene resin, both uncoated and coated,
after exposure to leaching solution for a period of 60 days. In all
tested solutions the specimens behaved satisfactorily, no disintegration
of any kind was observed during the entire period of testing.
Table A-9 presents the recorded values of pH, electrical conductance and
concentration of toxic elements in the leaching solutions during the test
period. In the aqueous and acidic solutions (Solutions A and B) shift of
pH towards alkalinity could be observed; pH changed little, if any, in the
alkaline and simulated solutions (Solutions C and D). There was a substantial
increase of the electrical conductance resulting from the leaching of the
uncoated specimen and only small changes resulting from the leaching of the
coated specimens.
Only arsenic and selenium diffused into the solution in significant
amounts fram the uncoated specimen leached in water. After 60 days of
leaching cadmium was found in concentrations below 3 ppm. Other elements
were not detected at all or appeared only in trace amounts.
The cemented and coated hazardous simulant specimens exhibited generally
satisfactory leaching resistance with regard to all tested elements except
selenium and mercury. Relatively high concentrations of selenium were
found in the alkaline leaching solution (Solution C) and of mercury in
the simulated leachate solution (Solution D).
A-25
-------
TABLE A-7. AVERAGE RATE OF DIFFUSION OF SODIUM IONS FROM SODIUM
CHLORIDE COMPACTS CEMENTED WITH PB RESIN INTO WATER
Exp.#
1
2
3
4
5
30
Specimen
Designation
Sodium chloride
cemented with
2% PB uncoated
Sodium chloride
cemented with
3% PB uncoated
Sodium chloride
cemented with
4% PB uncoated
Sodium chloride
cemented with
5% PB uncoated
Sodium chloride
cemented with
5% PB and coated
with PVC
Sodium chloride
cemented with
5% PB and coated
with PE/PB system
2
Average Rate of Diffusion g/day/m Between Days of Leaching
0 - 1
982
563
533
521
3.0
0.67
1 - 2
22
89
71
42
0.86
2 - 4
96
41
54
251
1.34
4 - 8
54
23
87
63
0.02
4.0
8-15
6.2
28
79
3.2
0.38
0.38
15-22
8.3
-
4.7
1.3
0.53
22 - 30
9.1
_
27
1.1
1.28
0.04
30 - 60
35
15
44
7.7
0.31
i
ro
-------
TABLE A-8. MECHANICAL PROPERTIES OF HAZARDOUS SIMULANT SPECIMENS CEMENTED WITH
7% PB RESIN FOLLOWING LEACHING IN DIFFERENT SOLUTIONS
i
po
Exp.
No.
6
7
8
9
10
Specimen Designation
Cemented, uncoated
Cemented, coated with PVC
As above
As above
As above
Leaching
Solution
A
A
B
C
D
Mechanical Properties
Hardness
35
30
40
Comp.
Strength
psi
211
333
537
141
268
Bulk
Density
g/cc
1.76
1.75
1.63
1.54
1.55
-------
TABLE A-9. PH, ELECTRICAL CONDUCTANCE AND CONCENTRATION OF TOXIC ELEMENTS
IN THE LEACHING SOLUTIONS OF HAZARDOUS SIMULANT SPECIMENS
CEMENTED WITH 7% PB RESIN
Exp.
No.
6
7
a
9
10
Specimen
Designation
Cemented
Un coated
Cemented
and
Coated
uith Dur
HI in rvi
Ceirenteu
and
Coated
HI tn PVC
Cemented
and
Coated
With PVC
Cemented
and
Coated
NUh PVC
Leaching
Solution
A
A
D
C
0
Property
pH
l.umhos/cm
cone. As ppm
conc.Hg ppm
conc.Se ppm
Cd
« Cr
n Pb ..
pN
x,umhos/cm
cone. As ppm
cone. Hg ppm
cone. Cd ppm
cone. Cr ppm
cone. Pb ppm
pH
i,umhos/cm
cone. As ppm
cone. Sc ppm
pH
X,umhos/cm
cone. 5e ppm
cone. Cr ppm
PH
x,umhos/cm
cone. As ppm
cone. Hg ppm
cone Se ppm
Days of Leaching
0
6.3
13.2
X
X
X
X
X
X
6.3
13.2
X
X
X
X
X
3.8
56.9
X
X
10.2
21.6
x!03
X
5.3
24.5
x!03
X
X
X
1
6.8
160
10.5
0.0
33.5
1.83
0.00
0.03
6.4
29.2
0.0
0.0
0.03
0.00
0.02
4.1
74.2
0.0
1.5
10.1
20.7
x!03
5f
0
0.00
5.3
24.5
x103
0.0
o.o
0.0
2
X
X
15. 2
0.0
X
X
X
X
X
X
0.0
0.0
X
x
X
X
X
X
X
X
X
X
X
*
X
X
X
4
6.7
254
23.0
0.0
X
X
X
X
6.3
27.3
0.0
0.0
X
X
X
4.2
75.5
X
X
10.0
18.7
xl03
X
5.3
24.5
xlOJ
X
X
X
8
6.8
420
31.3
0.0
167.6
3.10
0.02
0.15
6.4
12.2
0.0
0.0
0.07
0.01
0.03
4.2
49
0.0
0.0
10.0
21.6
xlO3
0.00
5.4
24.5
xlO3
0.0
C.O
0.0
15
6.9
611
27.5
0.0
165.7
3.16
0.00
0.10
6.4
44.2
1.0
0.0
0.11
0.00
0.02
4.2
65.9
0.8
3.0
9.9
18.8
xlO*
X
5.2
23.5
xlo3
0.0
0.5
0.0
22
7.5
790
27.9
0.0
X
X
X
X
7.6
56.5
1.1
0.0
X
X
X
4.5
96.0
X
X
10.1
19.8
xlO*
X
5.4
23.5
x!03
X
X
X
30
7.5
941
31.4
0.0
380
3.20
0.00
6.05
8.1
141
0.0
0.0
0.05
0.01
0.09
4.6
179
0.0
2.8
9.9
19.8
x!03
8.2
0.00
5.3
23.5
xlO3
0.5
2.0
0.0
60
7.8
941
118
0.0
450
2.55
0.00
0.80
7.9
141
0.0
0.0
2.6
0.14
0.00
0.10
5.2
179
0.0
2.8
10.0
18.8
XlO3
8.2
0.00
5.5
19.8
xlO3
0.0
5.4
0.0
0. I. Hater"
No Specimen
60 Days
6.7
282
0
0
0
0
0
0
6.7
282
0
0
0
0
0
X
X
X
X
X
X
X
X
X
X
X
X
X
0. I. Utttr*
With
Uncemented
Haste*
60 Days
9.4
1790
420
6.1
6.20
0.27
16.90
9.4
1790
420
6.1
6.20
0.27
16.90
X
x
X
x
X
X
X
X
X
X
X
X
a Reference (01 -
b iMg of hazardous
delonlzed water)
Haste dispersed In 750 ml water.
A-28
-------
Figures A-9, A-\0, and A-ll show the interface boundaries between the cemented
waste cores and the PVC coatings for specimens leached in acidic, alkaline
and simulated leachate solutions.
Some distortion occurred on the interface boundary in the alkaline solution
(Figure A-10), but none in the acidic or leachate solution. The alkaline
environment therefore appeared to reoresent the most aqaressive condition
among the tested solutions.
Figure A-9. Interface Boundary Between the Hazardous Simulant
Core Cemented with 7% PB Resin and Coated with PVC
After 60 Days of Leaching in Acidic Solution
(Magnification 6X)
A-29
-------
Figure A-10. Interface Boundary Between the Solid Waste Core Cemented
With 7% PB Resin and Coated with PVC After 60 Days of
Leaching in Alkaline Solution (Magnification 6X)
Figure A-11. Interface Boundary Between the Solid Waste Core Cemented
With 7% PB Resin and PVC Coating After 60 Days of Leaching
in Leachate Solution (Magnification 6X)
A-30
-------
DISCUSSION OF RESULTS OF ENVIRONMENTAL TESTING
Organic Cementation
Environmental testing revealed that polybutadiene resin is an adequate
cementing agent for the consolidation of solids. To the extent of the
testing performed both polyvinyl plastisol and polyethylene resin made
jackets suitable for separation of the hazardous compounds embedded
in the cemented core from the environment. Only traces of hazardous
elements other than selenium appeared in the solutions following 60 days
of leaching for specimens jacketed with polyvinyl chloride. Polyethylene
resin modified with polybutadiene yielded jackets superior to the polyvinyl
chloride suppressing diffusion of the sodium ions through the jacket;
however, this coating, developed at the end of the research period, was
not tested for penetration of heavy metal ions.
A-31
-------
APPENDIX B
B-l
-------
APPENDIX B
Figures B-l through B-8 are the calibration curves that were established
for each leaching solution. They were determined by a standard addition
analytical method. All concentration values for the cations in the leaching
test solutions were calculated from these curves. These calibration curves
are plotted through the average slope for each set of data points. The
scatter of these points is indicated on the graphs. The mercury calibration
data is listed, for all the solutions on one graph.
B-2
-------
Ha
Zn
11.0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Concentration (P.P.M.)
Figure B-l. Calibration Curves for the Cations in HCL and
Distilled Water Solution
B-3
-------
11.0
0.3 0.4 0.5
Concentration (P.P.M.)
0.7 0.8
Figure B-2. Calibration Curves for the Cations in the Citric
Acid Solution
B-4
-------
Zn (-12.18)
11.0
0.1 0.2
.3 0.4 0.5
Concentration (P.P.M.)
0.6 0.7 0.8
Figure B-3. Calibration Curves for Cations in NaOH Solution
. B-5
-------
c
f
o
01
11.0
10.0:
2.0
1.0
0.1
07?
0.
3 0.4 0.5
Concentration (P.P.M.
0.6
0.7
0.8
Figure B-4. Calibration Curves for Cations in NH4OH
B-6
-------
Zn Cd
11.0
Cr
Zn
0.3 0.4 0.5
Concentration (P.P.M.)
Figure B-5. Calibration Curves for Cations in Ocean Solution
B-7
-------
Na Zn Cd
11
Cr
T±m±J:t±-
rn i. iXLb-.Ti'l" r^bbtirr!" trr ~~~r_i:
;: j: :'-1-"-'-, --.::i:r;.L::----rc^-;~Fc_^;:,: rrrrn;^
L...li " L'L^' J. ' '~~c~-~-i.jr~ ," \~-frr<~'.~----r\"~"-~:(JT''
. [ - j r, ' r ~.'r' i -j^~ ~" ~if |~ ..! '. jr^";
0.1 0.2 0.3 0.4 0.5 0.6 0.7
Concentration (P.P.M.)
0.8
Figure B-6. Calibration Curve for the Cations in 10% Dioxane
Solution
B-8
-------
Zn Cd
11.0
, 0 3 0.2 '073 7 0.4 » 0.5 " ' 0.6 u 0.7 »
Concentration (P.P.M.)
Figure B-7. Calibration Curve for the Cations in the Ammonium
Sulfide Solution
B-9
-------
11.0
Ocean
1 (Others
345
Concentration (P.P.B.)
Figure B-8. Calibration Curves for Mercury in Leaching Solutions
(Except Ammonium Sulfide)
B-10
------- |