Although the PCF effectively treats soils contami-
nated with both organic and inorganic compounds, the
cost of this remediation technology is high because of
the capital cost of the equipment and the labor re-
quirement. The cost per ton for this technology depends
greatly on the waste feed rate to the furnace. For a
feed rate of 500 lb/hr, and an on-line percentage of
70%, the cost is estimated to be $1,816/ton; for a
2,200 lb/hr feed rate the cost becomes $757/ton. 7

|
3.3 Technology Evaluation \

The following discussions utilize all available information
to provide more detailed conclusions on the process, particu-
larly as related to chemical and operational test results. A
summary of the data from the Demonstration Tests is presented
in Appendix C; limited data from other tests conducted on this
technology may be found in Appendix D, “Case Studies.”
Detailed estimates regarding the cost of using this technology
are presented in a separate section of this report, Section 4,

“Economic Analysis.” '

The furnace evaluated during the Demonstration Tests is
a pilot-scale unit designated PCF-6 (the 6 corresponds to the
6-{t diameter of the primary chamber). The feed rate for the
PCF-6 during the Demonstration Tests was approximately
120 lb/hr. This unit has been subjected to the most extensive
testing, A full-scale system, PCF-8, that is designed to operate
at a feed rate of 2,200 Ib/hr, is in the process of being
permitted in Muttenz, Switzerland. For the purposes of this
Applications Analysis Report, only an evaluation of the PCF-
6 has been performed.

The feed soil used for the SITE Demonstration Tests'was
a mixture of metal-bearing soil from the Silver Bow Creek
Superfund site and No. 2 diesel oil. These were blended
together to provide 10% by weight diesel oil and spiked to
provide 28,000 ppm of zinc oxide and 1,000 ppm of hexa-
chlorobenzene. The diesel oil was mixed with the feed soil to
show that the process could treat wastes contaminated with
high levels of organics. Ten percent (10%) was the maximum
Ievel of liquid combustibles that could be fed to the furnace
equipped with the type of feeder present at the test site; levels
of diesel oil greater than 10% ignite in this feeder because of
the heat from the process. It is possible to treat contaminated
wastes with a higher percentage of organics using a different
feeder configuration assuming that the gas treatment system is
sized correctly. Zinc was spiked into the feed soil at the high
level to ensure that a metal was leachable from the feed soil in
sufficient quantities to allow comparisons with the treated
slag leachability. Hexachlorobenzene was spiked as a repre-
sentative stable (chlorinated) organic compound for the purpose
of evaluating the furnace’s ability to thermally destroy organic
hazardous compounds. The spiking level was chosen to ensure
that 99.99% DRE could be positively determined during the
Demonstration Tests.

3.3.1 Toxicity Characteristic Leaching Procedure

‘The PCF is designed to encapsulate inorganic compounds
in the vitrified slag and render the treated soil non-] -leachable.
Testing activities have demonstrated that the process! can

effectively bind inorganic compounds into the treated soil.
For the Demonstration Tests, the Toxicity Characteristic
Leaching Procedure (TCLP) was performed on both the feed
soil and the produced slag. The feed soil was tested to estab-
lish initial values for the leachability of organic and inorganic
compounds. The vitrified slag underwent TCLP to meet the
testing objectives.

For the Demonstration Tests, TCLP analysis of the feed
soil for metals shows that the only elements that exhibited
significant leachability characteristics were: calcium, sodium,
and the spiked zinc (see Table 1). The presence of sodium in
the leachate is not unexpected because of its high concentra-
tion in the soil and the fact that it is a weakly dissociable
metal. This means that sodium, unlike other metals, is readily
soluble. If the solution is even slightly acidic (as in the TCLP)
this phenomenon is enhanced. None of the eight RCRA
characteristic metals found in the feed soil leachate are above
the regulatory limit. The evaluation of the leachability of the
vitrified slag was based on calcium and zinc. Calcium was
chosen, in addition to zinc, because of its tendency to leach
from the feed soil. Sodium was not monitored because of its
unusual solubility characteristics as explained above.

The TCLP metals analysis of the treated soil is also
shown in Table 1. None of the metals, with the exception of
sodium, showed any strong characteristic for leaching. Sodium
is probably present in the leachate for the reasons stated above
and was not considered in this evaluation. Both tracer metals,
calcium and zinc, showed significant reductions in leaching
properties for the treated soil as compared to the feed. In fact,
all of the metals, with the exception of iron and aluminum
showed reduced leachability characteristics. The increase in
leachability of iron in the treated soil is probably because
approximately 100 Ib of mild steel was placed in the furnace
to aid in initiating the arc of the torch. This considerably
increases the iron content of the slag in comparison to the feed
soil. The leachability of the aluminum in both feed and treated
soil is low and the values reported for the treated soil are only
estimates (less than the quantitation limit). Therefore, it is
quite probable that the leachability of aluminum from the feed
soil as compared to that from the treated soil did not change.
TCLP testing on different feed soils by DOE has also shown
that the PCF produces a homogeneous non-leachable slag for
the metallic elements.

The only organic constituents that were found to be
leachable from the feed soil for the Demonstration Tests were
2-methylnaphthalene and naphthalene, as shown in Table 1.
Although the feed soil was spiked with a high level of
hexachlorobenzene (1,000 ppm), it did not leach from the soil.
No organic compounds were found to leach from the treated
slag.

The Toxicity Characteristic Leaching Procedure requires
samples to be ground into small particles. In this manner, a
large amount of surface area is available for leaching. Since
the PCF produces a monolithic slag after treatment, the surface
area per pound of treated soil is much smaller than that of the
feed soil. The TCLP results, therefore, present a conservative
assessment of the actual leachability of the monolithic slag.



Appendix B

Vendor’s Claims

This appendix summarizes the claims made by the devel-
oper, Retech, Inc., regarding the Plasma Centrifugal Furnace,
the technology under consideration. This appendix was gen-
erated and written solely by Retech, Inc., and the statements
presented herein represent the vendor’s point of view. Publi-
cation here does not represent EPA’s approval or endorsement
of the statements made in this section; EPA’s point of view is
discussed in the body of this report.

Retech, Incorporated (Retech), the developer of the Plasma
Centrifugal Furnace (PCF), states that the PCF system offers
three advantages over conventional rotary kiln incineration in
treating wastes. These are:

+ The PCF process produces slag that meets the re-
quirements for delisting and effectively destroys toxic
organic compounds.

The combination of vacuum-tight seals, sub-atmo-
spheric operation, leach-resistant product and high
DRE in the PCF process aids in obtaining community
acceptance.

Although PCF treatment costs are high ($600 to
$1200/ton), the ability to obtain a final solution for a
wide range of feedstocks makes this process cheaper
in many cases than the total costs of other treatments.

Discussion of these claims is presented in the three sec-
tions following: B.1 Treatment Effectiveness, B.2 Community
Acceptance, and B.3 Comparative Economics.

B.1 Treatment Effectiveness

Conventional incinerator ash frequently has identifiable
metallic residues, and the proximate analysis of kiln bottom
ash typically shows unburned carbon in the range of hundreds
to thousands of parts per million. However, in the PCF
process the mixing and intimate contact of unburned materials
with the metal oxides in the slag eliminates all fixed carbon
from the slag through carbon monoxide formation (the CO
subsequently reacts to CO,).

After cooling, the slag product from the PCF may be
glassy (non-crystalline) or crystalline, or a mixture of the two.
The degree of crystallinity is primarily determined by the

nature and proportions of the various metal oxides present in
the glass. The slag samples from the three SITE test runs
reported herein all had a fairly uniform mix and had similar
degrees of crystallinity. As noted in Section 3, all samples
satisfied the TCLP criteria. Retech has done leach tests on
PCF slag having different elemental compositions, resulting
ina wide range of crystallinity; in all cases, the leach resistance
of the slag formed was excellent.

To be delistable, solids must not represent a hazard to
health or the environment due to their form or properties.
Thus, the solids must not only pass TCLP tests in the form
produced, but adverse treatment reasonably expectable should
Not result in so much deterioration that the material would
then fail the tests. In one set of tests performed for Retech to
assess the effect of particle size on leach resistance, slag
crushed to -100 mesh met standards, but that crushed to -400
mesh had one metal in the leachate at an unsatisfactory level.

The SITE tests also evaluated the ability of the PCF-6 to
destroy hazardous organics. Hexachlorobenzene was chosen
as the additive to constitute a Principal Organic Hazardous
Constituent (POHC) because it is high on the list of compounds
hard to destroy, it contains chlorine, and it has a ring structure.

The quantity of hexachlorobenzene surviving was below
the detection limit in every sample taken during the three
tests. The sensitivity of the test was highest in the third SITE
Demonstration Test, sufficient to show the DRE was at least
“six 9’s”, i.e., >99.9999%. Furthermore, no Product of In-
complete Combustion (PIC) was found at a concentration
higher than permissible. The total hydrocarbon content of the
gas was congruent with this observation, well under 10 ppm.

The effluent stream in the Butte SITE tests was unsatis-
factory in one respect - dust. This was a result of inadequate
filtering. A production-size unit at Muttenz, Switzerland, was
measured in a government-supervised trial burn to have an
effluent dust load of 0.014, 0.0004, 0.0004, and 0.0004 grains
per dry standard cubic foot (converted from metric measure-
ment values of 14.0, 0.9, 0.9, and 0.9 mg/N°m*). Other mea-
surements in the trial burn showed NO, levels of 19 to 23 ppm
at the stack (downstream of NO, removal equipment). All the
government requirements on effluent were met in this test.

27



4.3.8 Effluent Treatment and Disposal Costs

One effluent stream is anticipated from the Plasma Cen-
trifugal Furnace process. This is the wastewater generated
from the scrubber system. The slag generated by the PCF
process is assumed to be a residual; see “Residuals and Waste
Shipping, Handling and Transport Costs”. Assuming the
implementation of an improved scrubber it is estimated that 4
Ib of scrubber discharge (a sludge) per ton of soil treated will
be generated.

Onsite facility costs are restricted to onsite storage of the
wastewater or sludge and assumed to be the obligation of the
site owner or responsible party. It is assumed that the waste-
water or sludge will be stored in approved 55-gal drums.

Off-site facility costs consist of wastewater disposal fees
and are assumed to be the obligation of the responsible party
(or site owner), not Retech. The disposal fee of both scrubber
water or sludge is estimated at $100/55 gal drum. The volume
of scrubber effluent generated will be less with a new and
more efficient scrubber, thus lowering the disposal cost; how-
ever the capital cost and other costs dependent upon the
capital cost will be higher. At a feed rate of 120 Ib/hr and 50%
on-line condition the overall treatment cost (including disposal
cost) of the PCE-6 varies little whether it is configured with
the scrubber used during the Demonstration Tests or a new
improved scrubber in operation. At higher feed rates and
higher on-line percentages, replacing the scrubber with a
more efficient scrubber produces a significant cost savings
over operating the PCF-6 with the old scrubber (if disposal
costs are included in the overall treatment costs). The PCF-8
already has a more efficient scrubber system than the one used
in the PCF-6 system during the Demonstration Tests.

Disposal cost of the scrubber effluent with the scrubber
used in the Demonstration Tests in place are estimated at
$455/ton of waste treated. With the new scrubber (discussed
above) in place the disposal cost of scrubber effluent is
estimated at $1/ton of waste treated. These are only estimates.
Disposal costs are highly dependent upon the type and volume
of hazardous waste generated.

43.9 Residuals and Waste Shipping, Handling
and Transport Costs

Waste disposal costs include storage, transportation and
treatment costs and are assumed to be the obligation of the
responsible party (or site owner). It is assumed that the only
residual or solid wastes generated from this process is the
slag. Landfill is the anticipated disposal method for this
material.

The slag generated by the furnace is anticipated to be
non- leachabie. If the slag can be delisted, it is assumed that it
may be disposed of for $10/ton of slag. Delisting costs are
highly dependant upon the type of waste being treated. If the
slag can not be delisted, it will be considered a hazardous
waste, and disposal cost may be much higher (dependant upon
the type of waste).

4.3.10 Analytical Costs

No analytical costs during operations are included in this
cost estimate. Standard operating procedures for Retech do
not require planned sampling and analytical activities. Periodic
‘spot checks may be executed at Retech’s discretion to verify
that equipment is performing properly and that cleanup crite-
ria are being met, but costs incurred from these actions are not
assessed to the client. The client may elect, or may be required
by local authorities, to initiate a sampling and analytical
program at their own expense.

The analytical costs associated with environmental moni-
toring have not been included in this estimate due to the fact
that monitoring programs are not typically initiated by Retech.
Local authorities may, however, impose specific sampling
and monitoring criteria whose analytical requirements could
contribute significantly to the cost of the project.

4.3.11 Facility Modification, Repair and
Replacement Costs

Maintenance costs are assumed to consist of maintenance
labor and maintenance materials. Maintenance labor and ma-

Table 7. Summary of Estimated Labor Costs In $/Ton for Varlous Feed Rates and On-line Operating Conditions

Treatment of 2,000 tons of Contaminated Soil

POF-6 PCF-6 POF-6 POF-8
120 Lb/Hr 500 Lb/Hr 1,000 Lb/Hr 2,200 Lb/Hr
On-line Factor On-line Factor On-line Factor On-line Factor
# of

oper.per Rates 50% 60% 70% 50% 60% 70% 50% 60% 70% 50% 60% 70%

Operators shift ($/hr) Labor Cost (#/ton) Labor Cost ($/ton) Labor Cost ($/ton) _ Labor Cost ($/ton)
Feed Operators 2 25 1,667 1,389 1,190 400 333 286 200 167 143 a1 76 65
Maintenance Operators 1 30 1,000 833714 240 200 171 120 100 86 55 45 39
System Operators 2 40 2,667 2,222 1,905 640 533 457 320 267 229 145 121 104
Total 5,334 4,444 3,809 1,280 1,066 914 640 534 458 291 242 = 208

23



i
for the Volatile Organic Sampling Train (VOST) is identical
in each case. These results are summarized and discussed in
Section 3, Table 2.

C.3 Acid Gas Removal and Particulate
Emissions i

Measured HCl emission rates ranged from 0.0007 to
0.0017 Ibfhr with an average emission rate of 0.0009 Tb/hr.
The chlorine concentration in the feed soil, as determined
during Test 1, was low, 0.066%. The regulatory requirement
of less than 4 Ib/hr was met. The HCl removal. efficiency was

As shown in Table 3 in the body of this report, particulate
emissions during the three tests range from 0.24 to’ 0.42
grains/dscf (uncorrected for 7% O,) with an average of 0.374
grains/dscf. This exceeds the Rt regulatory limit of 0.08
grains/dscf. Even higher values are expected when correcting
the results for 7% O, (see Section 3). The poor efficiency of
the scrubber with respect to particulate temoval is demonstrated
by the fact that there was less than 0.5% total solids in the

i
Table C-1. Stack Gas Composition
18/100 Ib
feed

scrubber sump tank, an amount insufficient for sampling and
analysis.

C.4 Air Emissions

The air emissions were chiefly comprised of products of
incomplete combustion (PICs) and particulates. Table C-1
presents a summary of the semivolatile organic compounds
emitted in the stack gas. The most dominant semivolatile
organic compound released in the stack gas was benzoic acid
at an average concentration of approximately 4 ppm. A group
of nitrated compounds was detected at levels less than 0.3
ppm. Other compounds such as the phthalate groups and
naphthalene were also present, but were found in the field
blanks as well. Some Tentatively Identified Compounds
(TICs) were present in the gas stream. No TICS could be
positively identified for Test 1, but it appears that some of the
unknowns contained oxygen somewhere in the molecular
structure and some of the unknowns are nitrogen-containing
compounds. In Test 2, several higher molecular weight
compounds were detected. The TIC data indicates that these
compounds were unidentifiable carbonic acids. Compounds

Somivolatites:
Acetaophenone
Banzolc Acid
Benzyl Alcohol
Butylbenzylphthalate
Dibutylphthalate
Diathlyphthalate
30 uiroiphano! ‘hala

is(2-Ethlyhexyl)phthalate
Naphthalene
Nitrobenzene
2-Nitrophenol
4-Nitrophenol

Metals:
Aluminum
Antimony
Arsanic
Barium
Beryllium
Cadmium
Calcium
Chromium

<2.15E-06
3.77E-04
<4.95E-07
<3.28E-07
<9.93E-07
<5.41E-05
2.13E-05
7.36E-05
1.68E-05
<3.13E-07
<8.56E-06
1.15E-05

CeCUDeoD
CoC Donon

5.02E-04
1.18E-05,
1.88E-03
4.26E-05
1.63E-07
1.76E-05
8.41E-04
3.39E-04
1.63E-03
1.51E-02
9.28E-04
2.01E-04
1.14E-04
1.38E-06
6.65E-05
3.76E-03
5.02E-06
2.88E-06
2.26E-03
5.52E-06
2.76E-05
3.01E-02

aD
BD

i]
—mb-

tron

inesium
Manganese
Mercury
Nickel
Potassium
Selenium
Silver
Sodium
Thallium
Vanadium
Zine

DoDHDHonon
DHDDHOHODHH

80.325

Ceoocd
BH Doan

DD
Do
Do

BoOHHDHHDHOH
DoODDODDOD
DHHHHDDHDHH
DOHDDHHOH

B

E- 0.091
5.53E-02 B_ 111.008

836E-02 B 163248 B

B Indicates that this compound was detected ina blank. |
J Estimated result. Indicates that result is less than the
<  Notdatected at or above the detection limit.

itation limit. Quantitation limit is five times the instrument detection limit.

32





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PCF-6 Data Plot

Test: ACT 2

Test Date: 7/3/91

Start Time: 8:40:0

Stack Gas Total Hydrocarbons
[

120 | 240
Time (min)

Figure D-1. Typical THC and CO Plot during ACTs.

PCF-6 Data Plot

Test: ACT 2

Test Date: 7/3/91

Start Time: 8:40:0

Stack Gas CO (Dry Meter) |

180 240

| Time (Min)

Figure D-2, Typical CO Plot during ACTs.



and hexachlorobenzene were spiked to provide 28,000|and
1,000 ppm, respectively, in the mixed soil. (The correspond-
ing amount of zinc is 22,500 ppm.)
Analysis of the feed soil showed that it contained volatile
compounds consistent with those associated with diesel fuel:
benzene, toluene, ethyl benzene, and xylene (BTEX). The
semivolatile compounds found most predominantly in, the
feed soil are the spiked hexachlorobenzene and 2-methyl-
naphthalene. Other diesel-based compounds were also found
in the soil but at levels that could not be accurately quantified
by SW-846 Method 8270. Gas chromatography/mass spec-
trometry (GC/MS) analysis also indicated the presence of
large numbers of TICs. These TICs were typical of those
found in diesel oil and consisted mainly of compounds of
naphthalene and benzene. The metals found most abundantly
in the feed soil were aluminum, calcium, iron, potassium,
sodium, and zinc. i

Volatile organic analysis was not performed on the treated
soil as no volatile compounds were considered to exist in the
slag after it had reached its melting point temperature. 'The
only semivolatile organic compounds found in the treated soil
were low levels of two phthalate compounds which were
probably sampling or analytical contaminants. This agrees
with the TCLP analysis of the slag discussed earlier in which
no semivolatile compounds leached from the slag. H

For the first Demonstration Test, 480 Ib of feed soil were
fed to the reactor and a steel “doughnut” weighing 74.5 Ib was
added. As the feed soil contained 10% organics, which appeared
to have been destroyed, a calculated 506.5 Ib of slag should
have been poured into the collection chamber. The mass of
treated soil collected in the slag chamber was 277 Ib, the
remainder being retained within the reaction chamber to
vide a “skull” for the next test. (A skull is a layer of melted
material around the interior of the primary chamber which
reduces the chamber’s volume and acts as an insulator to
protect the refractory.) Therefore, a mass balance that yields
meaningful results cannot be performed on this technology
since a Portion of material from each test can Potentially
remain in the reactor at the end of treatment, It is possible,
though, to compare the concentrations of the inorganic elements
in the feed soil with that of the collected slag, taking into
account the destruction of the 10% organics and assuming that
none of the elements are concentrated in the poured slag.
Table 4 gives the concentrations of the metals in the slag for
all three of the tests. The feed is an average of all feed samples
from the three tests, This table shows that a large percentage
of the metals from the feed soil are retained within’ the
vitrified slag. Exceptions to this trend are generally the vola-
tile metals: arsenic, lead, mercury, and zinc. These volatile
metals, as stated earlier, have been found to be exiting the
system through the exhaust stack. In addition, some of these
metals can be found in the scrubber liquor. '

To evaluate the fate of the feed soil metals, a comparison
can be made of the behavior of a non-volatile metal such as
aluminum to that of a volatile metal such as zinc. Test 3
provides a good basis for examination since 600 Ib of waste
were fed into the furnace and 595 Ib were poured. The feed
soil utilized during Test 3 contained 29.6 lb of aluminum. A

10

total of 26.0 pounds were detected in the treated soil. This
represents 88% of the aluminum originally present in the feed
soil. Traces of aluminum (0.00340 pounds total) were also
detected in the stack gas. A small increase in the aluminum
concentration from the pre-test scrubber liquor to the post-test
scrubber liquor was also noted. The remainder of the aluminum
which has not been accounted for may be due to sampling and
analytical variations.

For zinc, 13.9 Ib were fed to the furnace in the feed soil
during Demonstration Test 3. A total of 5.24 Ib (38%) was
retained in the treated soil. The stack gas contained 0.332 Ib of
zinc. A large portion of the zinc plated out as particulate
matter in the blower and the long exhaust gas duct. Again,
sampling and analytical variation may have contributed, in
part, to the apparent discrepancy between the zinc in the feed
soil and the zinc in the treated soil and the stack gas.

The increase in iron concentration can be explained by
the initial presence of the carbon steel doughnut. The concen-
trations of both chromium and nickel increase in the treated
slag because, prior to the Demonstration Tests, stainless steel
had been incorporated into the reactor to form part of the
skull. Additionally, the feeder chute used during these tests
was fabricated of stainless steel. The increase in the copper
concentration is probably because of the melting of portions
of the copper throat during treatment. In addition, soil treated
prior to the Demonstration Tests, and hence part of the skull,
had been high in calcium, manganese, and potassium.

Only the treated soil (not the feed soil) was analyzed for
PCDDs and PCDFs during the Demonstration Tests. The
levels of PCDDs and PCDFs in the treated soil for the
Demonstration Tests were very low. However, as described
earlier for the stack gas emissions, the detection limits for the
blank samples are higher than the amount of PCDDs and

Table 4. Metals In the Feed Soll and Treated Soil

Average
Feed
(ppm)
49,429
201

Test 3
(ppm)

43,667
. 1

Element Test 1

(ppm)
B 51,250
12

Test 2
(ppm)

46,000
16

Aluminum
Arsenic
Barium
Calcium
Chromium
Copper
Iron

Lead
Magnesium
Manganese
Mercury
Nickel
Potassium
Sodium
Vanadium
Zine

508 523
12,500 28,750
2 °* 500
780
36,929 B 160,000
426 98
5,725
1,850

ND

270
15,500
8,175

60
6,475 ©

4,650
814

1

NA

19,357
10,171

80
23,214

B indicates that this compound was detected in a blank

NA = Not Analyzed

ND = Not Detected

* = Detected at less than the quantitation limit. The quantitation limit
is defined as 5 times the instrument detection limit.

** = Instrument detection limit for mercury is 0.133 ppm.



i
|
|
|

The data from the Swiss tests show that the slag product
meets the requirements for delisting, and that toxic organic
compounds are destroyed effectively. SITE demonstration
testing data also support this claim (see Appendix C).

B.2 Community Acceptance

One of the problems associated with conventional ‘her-
mal treatment of hazardous wastes (i.e., rotary kilns) is that
pressure excursions (alias “puffs”) occur occasionally. Emit-
ted fumes can contain incompletely burned, and thus poten-
tially hazardous, substances. H

‘The gas seals on rotary kilns operate at high tempera-
tures, and essentially limit the flow to a quantity proportional
to the square root of the pressure difference between the kiln
interior and the outside atmosphere. The pressure difference
at usual operating conditions is typically a few inches of water
(4 in. of water column corresponds to 10 millibars or 1/100 of
Standard atmospheric Pressure). Any pressure surges more
than 10 millibars then result in leakage outward through the
hot seal,

The PCF furnace chamber, in contrast, has gas-tight seals
that do not permit untreated gas to escape, even at excess
pressures of 1,000 millibars (14.7 psig) or more. Thus the risk
of worker and community exposure is markedly reduced.

Retech’s experience in locating its SITE test program is
quite concordant with the statement above. After initial pre-
sentation of the concept to community leaders in August of
1988, newspaper stories described plans, and a media infor-
mation day was organized in mid-November which Started a
public comment period. No significant adverse reaction was
recorded. :

A larger-scale plant (PCE- 8) has been permitted in
Muttenz, Switzerland, again with no significant community
objection, In contrast, a plan by public authorities for siting a
regional rotary kiln incinerator encountered so much resistance
that the plan has been shelved. :

As the developer, we believe the inherent features of the
PCF process will help prospective users of the technology
obtain the consent of local communities for siting aPCF facility.

B.3 Comparative Economics

The cost per ton of material fed into the PCF depends not
only on the nature of the feed, but on the scale of the
equipment and the circumstances of the treatment (e.g.. ae \short
orlong program ata Superfund site, or permanent installati tion).
The sections below discuss the effects of scale, treatment
costs with the PCF-8 (a larger unit than the pilot-scale PCF-6
used for the SITE Demonstration) and the costs of alternative
treatments for the wastes for which PCF treatment is appro-
Priate,

B31 Effects of Scale

Retech’s first PCF had a tub diameter of only 18 in. (Le.,
a PCF-1.5, since the number in the furnace designation tefers

to the tub diameter measured in feet). We first operated it in
September 1987 and learned quickly that a very leach-resis-
tant slag was made when contaminated soils were placed in
the furnace. A large number of tests have been made in the
PCF-1.5 since then. The feeder system was improved to
enable more uniform feeding of solids. Operating with air at
about 150 kW, we found we could feed about 40 Ib/hr of dirt.
The specific energy consumption is then 3.8 kWh/per pound
melted.

With the pilot-size PCF-6, operators at Butte found, in a
series of shakedown runs, that they could melt about 500 Ib/hr
of soil with a torch power of 500 to 600 kW. The specific
energy consumption at 500 kW and 500 Ib/hr is then 1.0 kWh/
Ib. The SITE Demonstration tests were run at a significantly
lower feed rate (only 120 Ib/hr) to be compatible with a longer
run time (8 hr) for demonstrating operability. (Total feed for
the three replicate runs was limited to about 3,000 Ib, in order
to retain enough material for a fourth run (if one of the first
three was found to be unusable.) The specific energy con-
sumption during the three SITE runs, at 500 kW and 120 lb/
hr., is 4.2 kWh/lb. With the PCF-8 in Muttenz, the feed rate
with 1200 kW of torch power is one metric tonne per hour
(2,200 Ib/hr). At this size, the specific energy consumption is
0.55 kWh/Ib.

It is clearly desirable to consider whether substantial
further improvements are still possible. For this, we use two
pieces of information. Large-scale in situ vitrification tests
conducted by Battelle’s Pacific Northwest Laboratories and a
successor organization, Geosafe, resulted in a specific energy
requirement of 0.7 kWh/kg or 0.32 kWh/Ib. This is close to
the value of about 1,000 Btu/Ib. (0.29 kWh/Ib) obtained from
thermochemical data on typical soil constituents.

Table B-1 summarizes the above data and calculations.
Considering the losses inherent in a water-cooled wall furnace,
only modest further improvements in specific energy re-
quirement can be expected at sizes larger than the PCF-8.

Because the feed rate with the PCF-8 is four times as high
as the present configuration of the PCF-6, remediation times
would be much more acceptable with the PCF-8. We believe
it appropriate to use cost data for the PCF-8 when comparing
PCF economics with alternatives.

B.3.2 Treatment Costs with the PCF-8

The PCF technology is useful both for onsite remediation
and offsite treatment at a permanent location. The cost-per-
ton treatment is a function of the quantity treated per setup for

Table B-1. Specific Energy Data for Various Types of
Equipment

Equipment Type ific Energy

(kWh/b)

Melt Diameter
(ft)

1.2

POF-6 45 1.0
PCOF-8 7 0.55
isv


Foreword

The Superfund Innovative Technology Evaluation (SITE) Program was authorized in
the 1986 Superfund Amendments and Reauthorization Act (SARA). The Program is a joint
effort between EPA’s Office of Research and Development (ORD) and Office of Solid
‘Waste and Emergency Response (OSWER) to enhance the development of hazardous waste
treatment technologies necessary to implement new cleanup standards that require greater
reliance on permanent remedies. This is accomplished through technology demonstrations
designed to provide engineering and cost data on selected technologies.

This project consists of an analysis of the Retech, Inc. Plasma Centrifugal Furnace. A
series of Demonstration Tests took place at the Department of Energy's Component
Development and Integration Facility located in Butte, MT. The demonstration effort was
directed at obtaining information on the performance and cost of the process in order to assess
the potential applications at other hazardous waste sites. The Technology Evaluation Report
describes the field activities and laboratory results from the Demonstration Tests. This
Applications Analysis Report provides an interpretation of the available data, an economic
analysis, and a discussion of the potential applicability of the technology.

Additional copies of this report may be obtained at no charge from the EPA’s Center for
Environmental Research Information, 26 West Martin Luther King Drive, Cincinnati, OH,
45268, using the EPA document number found on the report’s front cover. Once this supply
is exhausted, copies can be purchased from the National Technical Information Service,
Ravensworth Bldg., Springfield, VA, 22161, 703-487-4600. Reference copies will be
available at EPA libraries in their Hazardous Waste Collection. You can also call the SITE
Clearinghouse hotline at 1-800-424-9346 or 202-382-3000 in Washington, D.C. to inquire
about the availability of other reports.

E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory



Cost in $/Ton , Feed Rate of 500 Ib/hr (PCF-6)

Supplies
Site Preparation

Facility Modification

Consumables

Equipment

Startup and Fixed

—

$500

$0

50% 60%

Figure 1. Summary of cost breakdown for 12 cost categories.

Cost in $ton I 2,200 ter (Pcr-8)
1,000 lb/hr (POF-6)

500 lb/hr (PCF-6)

EZ 120 lb/hr (PCF-6)

Percent On-Line

Figure 2, Summary of overall treatment costs of a PCF-6 and a PCF-8.

21



Table 1. TCLP Results for Demonstration Tests

Treated Soil Leachate Concentration

Average Feed Soil
Compound Leachate Concentration Test 1 Test 2 Test 3 Regulatory Limit*
(mg/l) (mg/L) (mg/t) (mg/h) (mgt)
Metals:
Aluminum 0.23"* 0.45** 0.41"* 0.32** NR
Barium 0.14 0.08 0.08 0.07 100.0
Cadmium 0.07 ND ND ND 1.0
Calcium 176 ai 25" 2.05** NR
Copper 46 0.15 0.35 0.3 NR
Jron 0.06 25 2.95 31.1 NR
Magnesium 8.12 ND ND ND NR
Manganese 4.82 0.06 0.06 0.24 NR
Nickel 0.02 ND 0.01** OT NR
Potassium 4.57 ND ND ND NR
Sodium 1,475 1,500 1,400 1,400 NR
Vanadium 0.1 ND ND ND NR
Zine 982 0.45 0.36 0.3 NR
Semivolatiles:
Napthalene 0.397 ND ND ND NR
2-Methyinapthalene 0.262 ND ND NDS NR
Hexachlorobenzene ND ND ND ND 0.13

ND = not detected
NR = Not Regulated
* = 40 OFR (07/01/90 Edition) §261.24, Table 1

* Detected at less than the quantitation limit. The quantitation limit is defined as 5 times the instrument detection limit.

3.3.2 Destruction and Removal Efficiency

The DRE, used to determine organic destruction, is de-
termined by analyzing for the Principal Organic Hazardous
Compound (POHC) in the feed soil and the stack gas. DRE
may be calculated as follows:

mass in - mass out

DRE (%) = X 100%

mass in

DREs have only been determined for this technology
during the SITE Demonstration Tests. For these tests, the
POHC was hexachlorobenzene. The mean level of hexachloro-
benzene, based on all the feed soil samples for the three
Demonstration Tests was 972 ppm. The 95% confidence
interval for the estimated mean was 864ppm to 1,080 ppm. No
hexachlorobenzene was detected in the stack gas, therefore,
all hexachlorobenzene DREs determined are based on the
detection limit from the appropriate tests. Table 2 gives these
DREs based on the 95% confidence interval of the feed soil
and the detection limit for each test.

As can be seen from Table 2, the estimated average DRE
values for these tests ranged from >99.9968% to >99.9999%
for a highly chlorinated compound, hexachlorobenzene. It can
be reasonably assumed that this level of DRE (if measurable)
can be achieved for most chlorinated or halogenated com-
pounds.

Analysis of the feed soil indicated that 2-methyInaphtha-
lene, another semivolatile compound, was present at suffi-
ciently high levels in the feed to determine a significant DRE
for each test. The 95% confidence interval for 2-methylnaph-

thalene was 390ppm to 526 ppm. This level of contamination
in the feed soil leads to the DREs given in Table 2, again
‘based on detection limits because none of this compound was
detected in the stack gas.

Total xylenes, a group of volatile compounds, were also
found in sufficient quantities in the feed soil to determine a
significant DRE. The 95% confidence interval for the esti-
mated mean of the total xylenes was 128ppm to 139 ppm. The
DREs associated with this confidence interval for the three
tests were >99.9929% to >99.9934%. Throughout each of the
Demonstration Tests, multiple Volatile Organic Sampling
Train (VOST) samples were taken. The DREs presented are
an average over all three tests based on the 95% confidence
interval of xylenes in the feed soil. Averages of all the DREs
can be taken because the detection limits obtained are the
same for all the VOST samples.

Overall, the PCF appears to be very efficient in destroy-
ing both volatile and organic semivolatile compounds when
both the primary reaction chamber and the afterburner are
operating.

3.3.3 Acid Gas Removal and Particulate
Emissions

Measured HCI emission rates for the Demonstration Tests
ranged from 0.0007 to 0.0017 lb/hr. The chlorine concentra-
tion in the feed soil for Test 1 was 0.066%. This leads to an
HCI removal efficiency of 98.5%. Because of the low chlorine
input, the regulatory requirement of no greater than the larger
of either 4 Ib/hr or 99% removal [40 CFR (07/01/90 Edition)
§264.343(b)] was met. The removal efficiency may not be



Generally, any site that can tolerate the construction of a
facility to accommodate the furnace is suitable for this tech-
nology.

3.4.7 Utility Requirements

The utility requirements include electricity, water, natu-
ral gas, and other gases. The basic electrical requirement for
accommodating the installation and operation of the furnace
is a 1,600-amp, 480-volts, 3-phase power supply for the PCF-
6. This requirement is increased to 2,000 amps and 600 volts
(3-phase) for the PCF-8. A plant cooling water supply (cooling
tower system) is necessary at a flowrate of 350 gpm for the
PCF-6 and 450 gpm for the PCF-8. Deionized water is
required for the torch cooling circuit and 150 gallons is
required for each charge. Five scfm of natural gas are needed
for the afterburner. The oxygen lance requires 30 scfm of
gaseous oxygen at 92 psia and 25 scfm at 92 psia of gaseous
argon is required for seal protection and clearing of viewports.

3.4.8 Size of Operation

The capacity of the Retech Plasma Centrifugal Furnace
system utilized during the Demonstration Tests (PCF-6) was
120 Ib/hr feed. soil input. However, this capacity can be
increased to 500 Ib/hr using the same torch and furnace if
modifications are made to increase the size of the feeder and
the slag collection pig. The ability to supply and remove
process gases must also be increased to accommodate a
higher feed rate. The gas treatment system will also require
optimization depending on the organic and water content of
the feed. The facility constructed for this pilot-scale furnace
was approximately 25 ft by 18 ft by 40 ft, a three tier
structure. The two upper tiers housed the soil processing
equipment, and the lowest tier housed the gas treatment
system.

The Retech process can be retrofitted to a variety of
facility sizes according to process design capacity. The
equipment layout is restricted by vertical alignment of the
reaction chamber, secondary combustion chamber, and the
collection chamber. The minimum height requirement for
this vertical alignment for the PCF-6 is 30 ft. The gas
treatment system may be placed accordingly to meet an
optimum facility design plan.

3.5 Applicable Wastes

The Retech furnace can be used to treat wastes contain-
ing either hazardous organic or inorganic compounds, or a
combination of both. The level of total organics in the feed is
not limited. However, the level of organics does influence
the choice of furnace feeder. Accordingly, the gas treatment
system has to be sized to match the organic content of the
waste. Liquid wastes can be fed to the furnace by means of a
liquid injection lance. The selection of feeder is also depen-
dent on whether the feed has been containerized or has been
excavated and stockpiled.

For the Demonstration Tests on the PCF-6, a screw
feeder in which the screw flights were welded to the interior

of a rotating drum was used to introduce the soil into the
primary reaction chamber. The upper limit of particle size fed
to the furnace for this feeder was 4 in. X 4 in. because of the

. clearance available in the feeder and the torch stand off. The

torch and primary chamber ‘themselves are not restricted to
this size limitation and may handle larger debris so long as the
performance of the torch is not affected (loss of arc).

The operation of the feed system on the PCF-8 is com-
pletely different. This unit operates by feeding 55-gal drums
to the furnace. The feed system operates as follows: the drum
enters from the drum storage area on a conveyor. The first
stop is a piercing station where, under a cover of nitrogen with
removal of the gases to the furnace, the drum is pierced. A
barrel pump is used to remove the major portion of any liquid
in the drum. This liquid is pumped directly to the liquid
injection lance in the furnace.

Pierced drums can then be placed on the feeder. After 5
drums have been charged to the feeder, the door is closed and
the space inside the drum feeder is purged with nitrogen. A
water-cooled and refractory-lined gate separates the feeder
chamber from the furnace. When it is time to treat a new
drum, the gate is raised, the conveyor moves one drum into
the furnace and a mechanism at the tip of a drum manipulator
pierces and clamps the lid. After the drum is clamped, it is
taised a little, the feeder conveyor retracts, and the gate is
closed. The manipulator then lowers the drum to a position
where the Rototrode® can cut it up. The Rototrode® is a
spinning water-cooled copper electrode. An arc between the
Rototrode® and the steel drum cuts the drum from the bottom.
The operator slices the drum so as to deposit a moderate
amount of waste at a time into the furnace. Prior to charging
any solids, holes are pierced at several levels of the drum to
remove any remaining liquid. After the drum has been cut up,
the top part of the drum which remains on the manipulator is
pushed off the manipulator. The drum is then melted as part of
the feed and becomes part of the slag.

The gas clean-up system must be sized to match the
organic content of the feed. The gas scrubbing unit used on
the PCF-6 for the Demonstration Tests is described in Appen-
dix A. The air pollution control device used on the PCF-8
utilizes different technologies to meet regulatory standards
and reduce disposal costs. The PCF-8 system operates by first

. mixing the exhaust from the secondary combustion chamber
_ with air to reduce the gas to a temperature of approximately

13

2,200°F. Downstream of the mixer is a heat exchanger which
recovers heat for use later in the process. The exhaust gases
then pass through a quench where water is added to reduce the
gas temperature to below 194°F, Beyond the quench is a pre-
wash and 2-stage ionizing wet scrubber. Both particulate and
acid gases are designed to be removed by the water in the
quench and ionizing wet scrubber. An exhaust blower forces
the gases to the section where NO, are removed. A heat ex-
changer, which uses oil as the heat transfer medium between
the hot gas heat exchanger and the heat exchanger utilized to
temove NO, raises the temperature of the gas from approxi-
mately 85°F to approximately 575°F. Ammonia is added to a
catalyst bed to reduce the NO, to design levels of below 50
ppm.



Table 2. DRE Results for Demonstration Tests

Compound Test 1 Test1 Test 2 Test 3 Regulatory Limit*
Duplicate

Hexachlorobenzene

Lower 95% Confidence Interval >99.9964 299.9982 >99.9990 >99.99989

Mean >99.9968 299.9984 299.9991 >99.99990 99.99

Upper 95% Confidence Interval 299.9971 >99.9986 >99.9992 >99.99991

(2-Methylnapthalene

Lower 95% Confidence Interval 299.9853 >99.9930 >99.9958 >99.99960

Mean 299.9872 299.9939 >99.9964 >99.99965 99.99

Upper 95% Confidence Interval >99.9891 299.9948 >99.9969 >99.99970

* 40 CFR (07/01/90 Edition) §264.343{a)(1)

chromatogram for the second test contained nitrogen and
oxygen within their molecular structure.

The third test data was very similar to the TIC informa-
tion gathered from Test 1. In general, for the three Demonstra-
tion Tests, only low levels of semivolatile organic compounds
were identified in the gas stream.

Very low levels of volatile organic compounds were
detected in the exhaust gas stream during the Demonstration
Tests. The most common of these compounds was benzene at
an average concentration of approximately 19 ppbv. DOE
testing of inert soils mixed with diesel oil has also resulted in
the detection of low levels of benzene in the stack gas.
Benzene and substituted benzenes are prevalent in many
forms throughout diesel oil and hence benzene is a readily
formed PIC. Other identified compounds in the stack gas
tended to be very low levels of chlorinated organics which
were not identified in the feed soil at the detection limits
achieved for the testing and therefore can possibly be PICs.

Sampling and analysis for polychlorodibenzodioxins
(PCDDs) and polychlorodibenzofurans (PCDFs) in the ex-
haust gas stream was accomplished during the Demonstration
Tests. The results of these analyses indicated that no PCDDs
or PCDFs were formed in the stack gas. Although some
PCDDs and PCDFs were detected in some of the samples
analyzed, the levels detected were lower than the corresponding
blank sample detection limit. For example, a particular isomer
ofa PCDD was detected with 10 picograms of catch; however,
the field blank reported a nondetect with a detection limit of

Table 3, Particulate Results for Demonstration Tests

Test! Test? Test2 Test3 Regulatory
Duplicate Limit

Particulate
Concentration 0.34 0.24 0.42 0.41 0.08
(grains/dscf)
Particulate
Emissions 0.34 0.24 0.42 0.42 ”
(lb/hr)

* 40 CFR (07/01/90 Edition) §264.343(c)
** Dependent on stack gas flowrate

20 picograms of catch. The variation of the detection limits is
a function of the matrix being analyzed and the resolution of
the analytical instruments used to quantify the samples,

Metal emissions during the Demonstration Tests were
almost exclusively in the solid phase; very little of the metals
were found in the impingers of the sampling trains. The only
significant vapor. phase metals detected were calcium and
mercury. A very volatile metal such as mercury is expected to
be found in the vapor phase. Zinc, copper, iron, potassium,
arsenic, and lead were in abundance in the stack gas in the
solid phase. The presence of iron in the stack gas, at 66 ppm,
was a consequence of the high levels of this element in the
feed soil and the need for using a mild steel “doughnut” for
Start-up purposes. The copper in the stack gas is suspected to
originate from the throat of the furnace and the torch electrode
as copper is not present in high quantities in the feed soil.
Lead, at approximately 4 ppm in the stack gas, and arsenic, at
6 ppm, were not retained in the treated soil as they are volatile
metals (arsenic sublimates) and most probably evaporated
from the soil while it was being treated in the furnace. The
high level of zinc in the stack gas, at approximately 125 ppm,
was a consequence of the high spiking level of this element
and the high volatility of this metal in the temperature range
encountered within the furnace. Additionally, the presence of
chlorine with the zinc at this temperature range rapidly in-
creases the volatility of zinc. In all cases, (except mercury) the
air pollution control system should have captured the metals.
As shown later, the scrubber liquor did not contain high levels
of metals after each of the tests.

Based on the results from the Demonstration Tests, it
appears that not all of the volatile metals are captured in the
molten soil at the completion of treatment. If this is the case,
then these volatile metals should be captured by the gas
treatment system (assuming it is correctly designed). A per-
centage of the volatile metals originally found in the soil
would appear in the scrubber liquor, therefore, possibly re-
quiring treatment of the liquor prior to disposal.

3.3.5 Test Soil and Treated Slag

As stated previously, the feed soil for the Demonstration
Tests consisted of a mixture of Silver Bow Creek Superfund
Site soil, which is classified as a high metal-bearing soil, and
10% by weight No. 2 diesel oil. Into this mixture, zinc oxide



i =(v- id+ip
Capital Recovery = (V - Vs) aae-1
Where V_ is the cost of the original equipment,
Vs_ is the salvage value of the equipment,
n__ is the equipment life (15 years), and
i is the annual interest rate (6%) [2,3].

4.3.4 Startup and Fixed Costs

For each project the PCF is commissioned (prior to the
commencement of treatment) a period of one week is required
for waste-specific testing of the furnace. This includes check-
ing out each of the systems individually for the particular
waste to be treated, prior to starting up the entire PCF. Seven
workers are required for 12 hr/day, 5 days/wk during the
waste-specific equipment testing. Costs of initial equipment
tests is limited to labor charges at a rate of $40/hr.

Working capital i is based on the amount of money cur-
rently invested in supplies and consumables. The working
capital costs of supplies and consumables is based on main-
taining a one-month inventory of these items. (See “Supplies
Cost” and “Consumables Cost” for the specific amount of
supplies and consumables required for the operation of the
PCE, These quantities were used to determine the amount of
supplies and consumables required to maintain a one- -month
inventory of these items.)

Insurance and taxes are usually approximately 1% and2
to 4% of the total equipment capital costs, respectively. |The
cost of insurance of a hazardous waste process can be several
times more than this. Insurance and taxes together are assumed
for the purposes of this estimate to be 10% of the equipment
capital costs [3].

The cost for the initiation of monitoring programs has not
been included in this estimate. Depending on the site and the
fixed facility of the PCF, however, local authorities may
impose specific guidelines for monitoring programs. |The
stringency and frequency of monitoring required may have
significant impact on the project costs.

Acontingency cost of 10% of the equipment capital costs
is allowed for any unforeseen or unpredictable cost: conditions,
such as strikes, storms, floods, and price variations [3,4].

43.5 Labor Costs

Labor costs are limited to salaries. Personnel required per
shift is estimated at: 2 feed operators at $25/hr, 2 system
operators at $40/hr and one maintenance operator at $30/hr.
Rates include overhead and administrative costs. It is assumed
that personnel will work an average of 40 hr/wk, thus there
will be 3 shifts for a 24-hr 5-day/wk operation. Table 7 shows
the labor costs for operating a PCF-6 with feed rates of 120,
500, and 1,000 Ib/hr and a PCF-8 with a feed rate of 2,200 Ib/

4.3.6 Supplies Costs

Based on data from previous operations, over a period
that reflects operating conditions similar to those experienced
during the Demonstration Tests, the costs for chemicals, spare
parts, and office/general supplies that are actually used to treat
each ton of waste are estimated at $20. Chemicals consist of
caustic soda for the neutralization of the scrubber liquor and
flocculent for water treatment.

4.3.7 Consumables Costs

Natural gas is required at approximately 4 scfm during
startup and while the PCF-6 is on-line. The cost of natural gas
for these cost estimates is assumed to be $5.00/million BTU,
with no monthly fee. The PCF-6 also requires 16 scfm of
oxygen and 11 scfm of argon. The cost of oxygen and argon is
estimated at $0.252/100 cf and $0.435/100 cf, respectively.

The full-scale PCF-8 operating at 2,200 lb/hr does not
require this 4 scfm of natural gas, but requires supplementary
fuel to startup the furnace and oxygen to promote combustion,
both available for an estimated cost of $40/ton of waste
treated.

The cooling water systems utilized by the PCF are all
assumed to be closed, therefore the only water required is for
the initial charge to the cooling water systems. With the
scrubber system used during the Demonstration Test, it is
estimated that 250 gal of scrubber wastewater per ton of waste
treated will be generated. With a new scrubber in place, it is
estimated that nearly all of the scrubber water will be recycled
back into the scrubber sump. For these cost estimates it is
assumed that an improved scrubber is in operation and the
PCF will require 50 gal of water per ton of waste treated.

For the purposes of these cost calculations the following
water rates, available for commercial use in Butte, MT are
used:

first 1,000 cf
next 4,000 cf
next 5,000 cf
next 60,000 cf
next 930,000 cf

$1.47/100 cf
$1.38/100 cf
$1.17/100 cf
$1.10/100 cf
$0.89/100 cf

The electricity required for the PCF is limited to the
electricity utilized by the plasma torch. During the Demon-
stration Test the torch used approximately 430 kW of elec-
tricity. These cost estimates assume that the PCF will require:

+ 430 kW for 120 Ib/hr feed rate;

* 600 KW for 500 lb/hr feed rate;

* 800 kW for 1,000 Ib/hr feed rate; and
* 1,200 kW for 2,200 lb/hr feed rate.

These cost estimates assume a flat rate of $0.06/kWh and no
monthly charge.



addition, there are limits to conclusions regarding Superfund
applications that can be drawn from a single field demonstra-
tion. A successful field demonstration does not necessarily
assure that a technology will be widely applicable or fully

developed to the commercial scale. The Applications Analy-
sis Report attempts to synthesize whatever information is
available and draw reasonable conclusions. This document
will be very useful to those considering the technology for
Superfund cleanups and represents a critical step in the de-
velopment and commercialization of the treatment technol-

ogy.

2.3 Key Contacts
For more information on the demonstration of the Retech

Plasma Centrifugal Reactor technology, please contact: '

1, EPA Project Manager concerning the SITE Demon-
stration:

Laurel Staley

US. EPA

Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268

(513)569-7863

Vendor concerning the process:

Max Schlienger
Retech, Inc.

P.O. Box 997
Ukiah, CA 95482
(707/462-6522



Tables

TCLP Results for Demonstration Tests....

DRE Results for Demonstration Tests ......

Particulate Results for Demonstration Tests

Metals in the Feed Soil and Treated So’

Estimated Costs in $/Ton of the PCF-6

Summary of Estimated Costs in $/Ton for Various Feed Rates and On-!
Condition:

Summary of Estimated Labor Costs in $/Ton for Various Feed Rates and On-line Operatin;
Conditions ..........044

Specific Energy Data for Various. Types of Equipment

Stack Gas Composition

Organic Compounds in the Feed Soil

Results of Scrubber Liquor Analysis for Metals ..

Summary of Test Resulsts and Land Disposal Restrictions

Summary of Stack Gas Resulsts and Regulatory Limits

Swiss Leach Test Results ..



Operations are assumed to be 24 hr/day (3 shifts), 5
days/wk, and 50 wk/yr. Based on an expected 60-hr
average lifetime of the torch electrode, there will be
2 cold startups per week: 1 startup at the beginning of
the week and the other to replace the torch electrode.
Site preparation and initial equipment testing opera-
tions are assumed to be 12 hr/day, 5 days/wk. Exca-
vation activities for site preparation will take place
concurrent with treatment. Waste-specific equipment
testing will take place before treatment is begun and
is assumed to be one week long. These cost calcula-
tions are based on treating a total of 2,000 tons of
waste.

Transportation costs of the waste feed from a con-
taminant waste site to a fixed facility of the PCF are
site- and waste-specific, and have not been included
in these cost calculations.

Operations for a typical shift require five workers:
two feed operators, one maintenance operator, and
two system operators. Each shift is assumed to be
eight hours.

Capital costs for equipment are not used directly, and
are limited to the cost of the furnace and any additional
equipment such as a feeder, a torch, a power supply,
and a scrubber. Percentages of the total equipment
cost are used for estimating purposes.

Many actual or potential costs that exist were not in-
cluded as part of this estimate. They were omitted because
site-specific engineering designs, that are beyond the scope of
this SITE project, would be required. Certain functions were
assumed to be the obligation of the responsible party or site
owner and were not included in the estimates.

4.2 Results of Economic Analysis

Data gathered during the Demonstration Test indicates
that a weekly prorated on-line factor of approximately 70%
most closely represents the operating conditions during this
period of time. The furnace was off-line to respond to opera-
tional problems and to bring the temperature of the furnace up
to operating temperatures. This on-line percentage is prorated
for one week operating 24 hr/day, 5 days/wk, and with 2
startups. Typical on-line percentages of the PCF range from
50% to 70%, thus cost calculations were performed for 50%,
60%, and 70% on-line conditions. The feed rate during the
Demonstration Test was approximately 120 Ib/hr. For this
feed rate, and a total treatment volume of 2,000 tons of
contaminated waste, the results of the analysis show a cost-
per-ton range from $7,037 to $9,611 for 70% and 50% on-line
conditions, respectively. These costs are considered to be
order-of-magnitude estimates as defined by the American
Association of Cost Engineers, with an expected accuracy
within +50% and -30%; however, because this is a new
technology, the range may actually be wider. Since the PCF-6
is currently at the pilot-scale level, the cost per ton of soil
treated is very high. If the PCF-6 is adapted to operate at a 500
Tb/hr or 1,000 Ib/hr feed rate, and with on-line conditions from
50% to 70%, the cost-per-ton range is far less; from $1,816 to

$2,447 and from $1,015 to $1,342, respectively. For the full-
scale unit (PCF-8), the cost-per-ton ranges from $757 to $978
for 70% and 50% on-line conditions, respectively. A PCF
operating at 120, 500, 1,000, and 2,200 Ib/hr will take ap-
proximately 9.4, 2.4, 1.1, and 0.5 years to cleanup 2,000 tons
of waste, respectively.

Figure 1 presents a breakdown of the costs for each of the
twelve cost categories for a feed rate of 500 lb/hr. Figure 2
presents the relative treatment cost of a PCF operating at a
feed rate of 120 to 2,200 Ib/hr and on-line conditions of 50%,
60%, and 70%. Both Figures 1 and 2 are based on treating a
total of 2,000 tons of contaminated waste. The results show
that, for a feed rate of 500 Ib/hr, the technology is labor-
intensive with approximately 52% of the total cost attributed
to labor. For higher treatment rates of the PCF-6, the percentage
of labor cost contributing to the total cost decreases, but the
technology is still labor-intensive. The startup and fixed costs
of the PCF-8, operating at 2,200 Ib/hr, make up approximately
33% of the total cost, while labor makes up approximately
29%. Together labor and startup and fixed costs make up
771%, T4%, 70%, and 62% of the total operating cost of a PCF
operating at 120, 500, 1,000, and 2,200 Ib/hr, respectively.

. These costs can be reduced by increasing the on-line percentage

and feed rate, thus increasing the actual treatment rate and
decreasing the treatment time required.

4.3 Basis for Economic Analysis
The cost analysis was prepared by breaking down the
overall cost into 12 categories:

Site and facility preparation costs,

Permitting and regulatory costs,

Equipment costs,

Startup and fixed costs,

Labor costs,

Supplies costs,

Consumables costs,

Effluent treatment and disposal costs,

Residuals and waste shipping, handling, and trans-
port costs,

Analytical costs,

Facility modification, repair, and replacement costs,
and

+ Site restoration costs.

The 12 cost factors examined as they apply to the Plasma
Centrifugal Furnace process, along with the assumptions em-
ployed, are described in detail below. Except where specified,
the same assumptions were made for the costs of operating a
PCF at 120, 500, 1,000, and 2,200 Ib/hr.

4.3.1 Site and Facility Preparation Costs

For the purposes of these cost calculations “site” refers to
the location of the contaminated waste and “facility” refers to
the fixed location where the PCF is operated. The contaminant
‘waste must be transported from the site to the fixed facility of

the PCF,

19



3.7.2 Health and Safety

The health and safety issues involved in using the Retech
system for waste immobilization are generally the same as
those that apply to all hazardous waste treatment facilities as
detailed in 40 CFR 264 Subparts B through G, and Subpart X.
Specific issues including high temperature operation induced
by the plasma torch and high voltage must also be taken i into
consideration.

3.7.3. Emergency Response l

‘The emergency response training for using the Retech
system is the same general training required for operating a
treatment, storage and disposal (TSD) facility as detailed in 40
CER 264 Subpart D. Training must address fire and coniain-
ment-related issues such as extinguisher operation, hoses,
sprinklers, hydrants, smoke detectors and alarm systems, self-
contained breathing apparatus use, hazardous material spill
control and decontamination equipment use, evacuation,
emergency response planning, and coordination with outside
emergency personnel (e.g., fire/ambulance).

3.8 Summary

The Retech, Inc. Plasma Centrifugal Furnace is an inno-
vative thermal technology that can treat wastes contaminated
with both organic and inorganic compounds. For this reason,

this technology may be useful in the treatment of Superfund
site wastes.

The main disadvantages of this system are high particu-
late emissions, high NO, concentrations in the stack gas, and
the cost of remediation. The problem of the high particulate
emissions can easily be rectified by means of a more efficient
gas scrubbing system. The high NO, levels in the stack gas
Tesult from the use of air as the torch and purge gases.
Altemate torch and purge gases may negate or substantially
reduce NO, emissions. This will be investigated as part of
DOE portion of these studies. The NO, levels in the exhaust
stream may be of concern with state and regional regulatory
agencies. Many states have more stringent requirements than
that of the Federal Government. Federal requirements state
that the NO, emission rate must be less than 9.2 Ib/hr (40 tons/
yr based on operation 365 days/yr, 24 hr/day). In some
severely polluted areas of the country, this may be reduced to
2.2 Ib/hr (10 tons/yr per based on operation 365 days/yr, 24 hr/
day.) The PCF-6 does not exceed this 9.2-Ib/hr standard, but
the concentration in the stack gas is high. Many state and
tegional authorities are basing the NO, level requirements on
concentration not emission rates. These stringent require-
ments will necessitate the installation of expensive NO, con-
trol devices for the PCF, further increasing the cost of
remediation. A full discussion of the costs of this technology
is presented in Section 4.



Contents

Acknowledgments...

1. Executive Summary...

1.1 Introduction
1.2 Conclusions
13 Results...

2. Introduction...

2.1 The SITE Program
2.2. SITE Program Reports
2.3 Key Contacts .....

3. Technology Applications Analysis
3.1 Introduction
3.2 Conclusions
3.3 Technology Evaluation

3.3.1 Toxicity Characterist
3.3.2 Destruction and Removal Efficiency ....
3.3.3 Acid Gas Removal and Particulate Emissions
3.3.4 Air Emissions...
3.3.5 Test Soil and Treated Slag .
3.3.6 Scrubber Liquor ..
3.3.7 Continuous Emission Monitors ..
3.3.8 Furnace Operation ....
,3.4 Ranges of Site Characteristics Suitable for the Technology .
. 3.4.1. Site Selection .....
3.4.2 Surface, Subsurface, and Clearance Requirements
3.4.3 Topographical Characteristics
3.4.4 Site Area Requirements
3.4.5 Climate Characteristics
3.4.6 Geological Characteristic:
3.4.7 Utility Requirements
3.4.8 Size of Operation

3.5 Applicable Wastes...

3.6 Regulatory Requirements
3.6.1 Federal EPA Regul
3.6.2 State and Local Regulations

‘3.7 Personnel Issues ....
3.7.1 Operator Training ..
3.7.2 Health and Safety ..
3.7.3 Emergency Response.

3.8 Summary

4. Economic Analysis



Abstract

This document is an evaluation of the performance of the Retech, Inc. Plasma Centrifu-
gal Furnace (PCF) and its applicability as a treatment for soils contaminated with organic
and/or inorganic compounds. Both the technical and economic aspects of the technology
were examined,

A demonstration of the Retech furnace was conducted under the SITE Program at the
Department of Energy's Component Development and Integration Facility in Butte, MT.
Operational data, along with sampling and analysis information, were carefully compiled to
establish a data b ase against which other available data, as well as the vendor's claims for the
technology, have been compared and:evaluated. Conclusions concerning the technology's
suitability forusein immobilizing contaminantsin the feed soil werereached, and extrapolations
regarding applications at other sites with different contaminants and soil types were made.

The following were derived mainly from the results of the Demonstration Tests and
supported by other available data: (1) the treated soil did notleach any RCRA metals at levels
above the regulatory limits; (2) the process achieved a Destruction and Removal Efficiency
(DRE) of greater than 99.99% for the Principal Organic Hazardous Constituent (POHC),
hexachlorobenzene; (3) the air pollution control system did notreduce the level of particulate
emissions to below the RCRA limit; (4) a high percentage of the metals fed to the furnace are
encapsulated in the treated soil; (5) the PCF is advantageous over conventional incineration
technologies in that it can successfully immobilize heavy metals in the slag. However, this
treatment option can be comparatively more expensive.



Section 3

Technology Applications Analysis

3.1 Introduction

This section of the report addresses the applicability of
the Retech Plasma Centrifugal Furnace (PCF) to treat various
potential soil contaminants and types of soils based primarily
upon the results obtained from the SITE demonstration as
well as additional tests performed by DOE. Since the results
of the Demonstration Tests provide the most extensive data
base, conclusions on the technology’s effectiveness and ap-
Plicability to other potential cleanups are based mainly on
those results, which are presented in detail in the Technology
Evaluation Report. Additional information on the Retech
technology, including vendor's claims, a brief process de-
scription, a summary of the Demonstration Tests results, and
reports on outside sources of data using the Retech technology
are provided in Appendices A through D.

Following are the overall conclusions drawn on the Retech
technology. The “Technology Evaluation” subsection dis-
cusses the available data from the Demonstration Test, the
Department of Energy (DOE) tests, and Retech provided
literature. This subsection also provides more details on the
conclusions and applicability of the Retech process.

3.2. Conclusions

The effectiveness of the PCF in encapsulating heavy
metals and destroying organic compounds was tested at The
Component Development and Integration Facility (CDIF) in
Butte, Montana. The CDIF is a DOE facility operated by
MSE, Inc. DOE is evaluating the PCF to determine if this
technology is suitable for remediation of contaminated soils
and sludges at the Idaho National Engineering Laboratory.

In general, this innovative technology is successful in
producing a monolithic slag that is non-leachable for inorganic
compounds and, in the process, destroying organic compounds
by the extreme heat of the process. The limiting factor in the
process with the present configuration is the gas treatment
system. The scrubber did not remove particulates generated or
volatilized metals from the exhaust gas during the treatment
process for the Demonstration Tests. However, this shortcom-
ing can be rectified by replacing the existing system with a
proven gas treatment system. The overall cost of treatment for
this technology is high but it can treat media contaminated
with both organic and inorganic compounds.

The conclusions drawn from reviewing data on the Re-
tech PCF are:

+ The PCF process can treat media contaminated with
both organic and inorganic compounds, producing a
slag in which the regulated contaminants are non-
leachable.

. The Destruction and Removal Efficiency (DRE) of
organic compounds is greater than 99.99% (the regu-
latory limit).

«Particulate emissions generated by the process, as
determined during the Demonstration Tests, exceed
0.08 grains/dscf, the RCRA regulatory limit.

. Although NO, concentrations in the stack gas are
high, emission rates fall within regulatory limits be-
cause of the low flow rates of the stack gas.

. The vitreous slag captures and retains a high percent-
age of the metals from the feed soil. A fraction of the
more volatile metals evolves from the feed and passes
through the furnace and the gas scrubbing system
without being captured.

+ The scrubber used for the Demonstration Tests was
inadequately designed for effective capture of volatile
metal elements and removal of particulates.

+ The PCF can treat a wide range of soil and sludge
types and contaminants. The feeder selection is dic-
tated by the type of feed. Liquids can be processed by
feeding the waste through a liquid injection lance.

. The PCF used during the Demonstration Tests (PCF-
6) is not mobile. Retech estimates that setup time for a
commercial unit will be approximately 2 months. This
time is required for installation, erection, and shake-
down of all equipment prior to operation of the system.

+ The system, as presently designed and operated, must
be erected within an enclosed facility. Onsite support
such as adequate power supply (at least 1 MW),
cooling water, and cranes for lifting are also required.



Figures

Summary of Cost Breakdown for 12 Cost Categories ..
Summary of Overall Treatment Costs of a PCF-6 and PCF-:
Schematic of the Plasma Centrifugal Furnace
Typical THC Plot During ACTs
Typical CO Plot During ACTs....

vii



PCDFs detected in the samples. It is therefore reasonable to
conclude that no PCDDs or PCDFs were formed by the
treatment process, and if any dioxins/furans were in the feed
soil they were destroyed by the intense heat of the process.

3.3.6 Scrubber Liquor

The pre-test scrubber liquor for each of the three Demon-
stration Tests contained very little in the way of organic
compounds. A metals scan on the pre-test scrubber liquor
showed that, generally, only low levels of inorganic elements
were present. This was expected since, prior to each test, the
scrubber sump was flushed and filled with deionized water.

The post-test scrubber liquor did not contain any signifi-
cant quantities of organic compounds. Nitrated compounds
and phthalates were the only compounds present. The nitrated
compounds were most likely produced from the high levels of
NO, in the exhaust gas reacting with the water from the
scrubber and any organic compounds present. The phthalates
and volatile organic compounds probably entered the scrubber
sump from the scrubber make-up liquor. The lack of organic
compounds in the scrubber liquor and, as stated earlier, the
absence of volatile or semivolatile organic compounds in the
exhaust gas, indicates that combustion of the organic com-
pounds was complete,

The scrubbing unit is very inefficient in the capture of the
inorganic compounds. The scrubber did capture some of the
volatile metal elements but not at the levels that would typically
be expected from a well-designed system. As stated previ-
ously, the exhaust gas contained a variety of metals that
should have been captured by the scrubbing unit. The types of
metals found in the scrubber liquor were similar to those
found in the stack gas; that is, zinc, iron, and arsenic were the
elements in abundance. High sodium levels found in the
liquor were probably a consequence of the scrubber make-up
(sodium hydroxide).

3.3.7 Continuous Emission Monitors

Throughout each of the three Demonstration Tests, CO,
CO,, O,, NO,, and total hydrocarbons (THC) were monitored
continuously to present a real time image of the combustion
process and to determine if regulatory standards were being
exceeded. SO, was also measured but the data collected was
not considered suitable. High levels of NO, in stack gas are
known to interfere with SO, meters, and the interference in-
dicates the presence of SO, when none is actually present.
MSE, Inc. has also monitored the same combustion products
for DOE during shakedown tests and other testing of the PCF.

Since the installation of the afterburner in the secondary
combustion chamber, the level of total hydrocarbons exiting
the system has been low (<4 ppm) even with at least 10%
organics in the feed soil. This gives a good indication that
effective thermal destruction of the organic compounds is
occurring. Another indication of the ability of the process to
treat organic contaminated media is the low levels of CO in
the exhaust (approximately 1.4 ppm) and the level of co,
(approximately 8%). O, monitors show significant variation
throughout the treatment process as pure O, is fed to the pri-

ll

mary chamber at approximately 18 scfm while waste is being
fed to the furnace.

High levels of NO, are a consequence of this process if
air is used as the torch gas. The torch gas passes through the
extremely hot arc of the plasma, thus oxides of nitrogen are
readily formed. Testing to date has shown that the average
concentration of NO, in the stack gas is approximately 5,000
ppm (uncorrected 10 7% O, as explained earlier). The oxygen
lance operated intermittently rather than continuously during
Tests 1 and 3. During Test 2, however, the oxygen was fed at
a steady rate over the entire treatment time, so the NO, values
corrected to 7% O, may be easily calculated for this test, if
desired. This correction is not required by RCRA regulations
because the system operates under oxygen enrichment. The
average uncorrected NO, value during Test 2 was 5,467 ppm;
the average NO, value corrected to 7% O, was 8,514 ppm.

The uncorrected average NO, value for testing (5,000 ppm)
corresponds to an emission rate of 2.6 lb/hr. The low emission
rate is because of the low flowrate of the exhaust gas (ap-
proximately 110 scfm). This flowrate is dependent on the size
of the torch used. The feed rate of the soil does not influence
the level of NO, in the exhaust assuming the same torch is
used for the different feed rates. This is because the torch uses
the same amount of torch gas regardless of the feed rate of
soil. If a torch larger than that used in the Demonstration Tests
is to be employed, then the use of an NO, reduction technol-
ogy should be investigated.

3.3.8 Furnace Operation

Since all three Demonstration Tests were designed to be
identical in nature, operating conditions during the tests were
telatively constant. The feed material was identical in each
case, a mixture of Silver Bow Creek soil and 10% by weight
No. 2 diesel oil, spiked to provide 28,000 ppm zinc oxide
(22,500 ppm zinc) and 1,000 ppm hexachlorobenzene. The
feed rate for each test was 120 lb/hr. Although the mass of
material to be fed during each test was anticipated to be 960
Ib, the actual weight of the feed was 480, 360, and 600 Ib for
Tests 1, 2, and 3, respectively. The corresponding weight of
the treated soil generated during the tests was 277, 265, and
595 Ib. The difference between the mass fed and the mass
poured during each test can be accounted for by the retention
of material inside the chamber as part of the skull as described
in Section 3.3.5. As demonstrated by these values, the skull
was progressively built up throughout the course of the
Demonstration Tests.

The torch power ranged from an average of approximately
410 KW during Test 3 to nearly 460 kW during Tests 1 and 2.
The total power consumption of the torch ranged from 3,308
kWh (Test 1) to 4,720 kWh (Test 3). As anticipated, the total
power consumption for Test 3 was greater than the other two
tests because of the extent of its duration. The torch gas in
each case was air with a flowrate of 23 to 24 scfm.

The furnace is operated so that a minimum temperature of
2,100°F is achieved in the primary reaction chamber and a
minimum temperature of 1,800°F is reached in the afterburner
before feeding of the waste is initiated. The reactor chamber



United States Office of Research and EPA/B40/A5-91/007

Environmental Protection Development June 1992
Agency Washington DC 20460

Retech, Inc.,
Plasma Centrifugal Furnace

Applications Analysis Report
rd ,
‘oe if

SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION



‘The post-test scrubber liquor did not contain any significant
quantities of organic compounds. Only nitrated compounds and
phthalates were present. The scrubbing unit was very inefficient
in the capture of the inorganic compounds. Table C-3 shows
that the scrubber did capture some of the metal elements, but not
near the expected levels for a well-designed system.’ The
distribution of metals in the scrubber liquor is similar to that
found in the stack gas. This is a clear indication of the poor
ability of the scrubbing system to remove the inorganic con-
taminants from the exhaust gas stream. The sodium is a
consequence of the scrubber make-up (sodium hydroxide) and
the silicon is most likely from the sandy nature of the soil.

C.7 Continuous Emission Monitoring

Throughout each of the Demonstration Tests, emissions
including CO, CO,, O,, NO,, and total hydrocarbons (THC)
if

were continuously monitored. SO, was also monitored, but
the data collected was not considered valid (see Section 3).

The THC level exiting the system was low (<4 ppm)
during the Demonstration Tests. This indicates that thermal
destruction of the organic compounds was occurring effec-
tively. Other indicators of this include the low levels of CO
and CO, in the exhaust gas (approximately 1.4 ppm and 8%,
respectively.) O, levels demonstrated wide fluctuations cor-
responding to the inlet of pure O, during feeding of the test
soil. High levels of NO, (approximately 5,000 ppm
uncorrected to 7% O,, see Section 3) were observed during
these tests since air was utilized as the torch gas. Because of
the low flowrate of the exhaust gas, the corresponding
emission rate is 2.6 lb/hr.



Maximum contaminant Levels Goals
Milligrams

National Ambient Air Quality Standards
National Pollutant discharge Elimination System
Office of Research and Development

Office of Solid Waste and Emergency Response
Plasma Arc Fumace Experiment
Polychlorodibenzodioxin
Polychlorodibenzofuran’

Plasma Centrifugal Furnace

Product of Incomplete Combustion

Principal Organic Hazardous Constituent
Publicly Owned Treatment Work

Parts per billion, by volume

Parts per million

Parts per trillion

Prevention of Significant Deterioration

Pounds per square inch, ‘absolute

Pounds per square inch, gauge

Percent

Resource Conservation and Recovery Act
Science Applications International Corporation
Superfund Amendment and Reauthorization Act
Standard cubic feet per minute

Safe Drinking Water Act

Superfund Innovative Technology Evaluation
Standard Soil Matrix
2,3,7,8-Tetrachlorodibenzodioxin
2,3,7,8-Tetrachlorodibenzofuran
Tetrachloroethylene

Toxicity Characteristic Leaching Procedure
Total Hydrocarbons :

Tentatively Identified Compound

Treatment Storage, and Disposal

Volts

Volatile Organic Sampling Train

Week

Year



ACL
AQMD

BDAT
BTEX
CAA
CDIF
CEM
CERCLA
cf

CWA
DAS

Abbreviations and Symbols

Amps

Alternate Concentration Limit

Air Quality Management District

Applicable or relevant and Appropriate Requirements
Best Demonstrated Available Treatment
Benzene, Toluene, Ethyl benzene, and Xylene
Clean Air Act

Component Development and Integration Facility
Continuous Emission Monitor
Comprehensive Environmental Response, Compensation, and Liability Act
Cubic feet

Code of Federal Regulations

Clean Water Act

Data Acquisition System

Department of Energy

Department of Transportation

Destruction and Removal Efficiency

Dry standard cubic feet

US. Dollar

Environmental Protection Agency

degree Fahrenheit

Feet

Federal Water Quality Criteria

Gallons

Gallons per Minute

Grains

Hour

Idaho National Engineering Laboratory
Kilograms

Kilowatts

Pounds

Liters

meters





Table 5. Estimated Costs In $/Ton of the PCF-&

On-Line Factor
Factor Feed Rate of 500 Ib/hr, Treating a total of 2,000 Tons 60%

Rasiduals & Waste Shipping, Handling & Transport Costs
Proparation 1 _
Waste disposal _—

Total Residuals & Waste Shipping, Handling & Transport Costs _

Analytical Costs
rrattic

Environmental monitoring
Total Analytical Costs

Facility Modification, Repair, & Replacement Costs
Dasign adjustments
Facility modifications
Schedulad maintenance (materials)
Equipment replacement
Total Facility Modification, Repair, & Replacement Costs

Site Restoration Costs :
Site cleanup and restoration . _
Permanent storage 0
Total Site Restoration Costs i 0

Total Operating Costs($/Ton) i 2,447 2,079 1,816

* Cost for treating a total of 2,000 tons of contaminated soil. |

* This cost is reported in “$", not “$/ton’. It is not used directly, but is used for estimating other costs (ie., annualized equipment cost,
insurance and taxes, scheduled maintenance, and contingency).

¢ This cost is estimated at less than one dollar per ton of waste treated.

Table 6. Summary of Estimated Costs in $/Ton for Various Feed Rates and On-line Operating Conditions
PCF-6 i PCF-6 PCF-6 PCF-8
120 Lb/Hr ' 500 Lb/Hr 1,000 Lb/Hr 2,200 Lb/Hr
On-line Factor On-line Factor On-line Factor On-line Factor

Treatment of 2,000 Tons of ‘|
Contaminated Soil 50% 60% 70% 50% 60% 70% 50% 60% 70% 50%

‘Sita Preparation Costs 179 154 137 61 56 49 46 44
Pormitting and Regulatory !
‘osts _ _- - - - - -

Equipment Costs 998 713
Startup and Fixed Costs 1,808 1,552 405 273° 239
Labor Costs 5,334 4,444 3,809 914 534 458
Supplies Costs 20 20 20 20 20 20 20
Consumables Costs 599 581 575 120
Effluent Treatment and

Disposal Costs oO 0 oO : oO 0
Rasiduals & Waste Shipping, .

Handling & Transport Costs - _ - -
Analytical Costs oO oO oO 0
Facility Modification, Repair,

& Replacement Costs 323 269 H 38
Site Demobilization Costs 0 0 0 0

Total Operating Costs($/Ton) 9,611 8,107 2447 2,079 1,816 1,342 1,150 1,015

In order for the PCF-6 to operate at a fixed facility, secondary cooling water system; a 45 ft high indoor
the facility must have a secondary cooling water facility; and 2,000 A, 600 V, 3-phase electrical power.
system of 350 gpm; an indoor structure to operate the For these cost calculations it is assumed that the
furnace with a minimum vertical height of 30 ft; and fixed facility will support all of these requirements of
1,600 A, 480 V, 3-phase electrical power for; the the PCF, The cost of preparing a facility to meet
main furnace. The PCF-8 requires at least a 450 gpm these requirements can be very high.



Appendix D

Case

D.1 Preliminary Testing

D.1.1 Description

Prior to the Demonstration Tests, a series of Preliminary
Tests were conducted by SAIC, as part of the SITE program,
to assess the performance of Retech’s Plasma Centrifugal
Furnace (PCF) [1]. Three tests were originally scheduled,
however, Preliminary Test 2 was only partially completed due
to equipment failure. Preliminary Test 1 utilized 550 Ib of
unspiked synthetic soil matrix (SSM) prepared by EPA. Pre-
liminary Test 3 utilized 200 Ib of SSM spiked with the
following compounds:

Volatiles:
* 1,200 ppm tetrachloroethylene (TCE)

Semivolatiles:
* 1,800 ppm anthracene
4,000 ppm bis(2-ethylhexyl)phthalate

Metals:
* 1,000 ppm chromium
16,000 ppm zinc.

The Preliminary Testing activities included sampling and
analysis of the feed soil, the treated soil, the scrubber liquor,
and the stack gas. The stack gas was also monitored throughout
the tests using Continuous Emission Monitors (CEMs).

D.1.2 Testing Protocol

Test 1 was conducted to evaluate background contami-
nation levels of phthalates in the feed soil, scrubber discharge,
and stack gas, so as to allow accurate determination of bis(2-
ethylhexyl)phthalate in these matrices during subsequent tests.
This was necessary since phthalate contamination is prevalent
from a wide variety of sources. In addition, the stack gas was
monitored for emissions of CO, CO,, O,, NO,, and THC.

In Test 3, the feed soil samples, treated soil samples,
scrubber makeup samples, and scrubber liquor samples were
analyzed for organics, metals, EP Toxicity (except scrubber
makeup and liquor), and ash fusion temperature (feed soil
only). The stack gas was sampled for organics, metals, par-
ticulates, and moisture, and was continuously monitored for
CO, CO,, O,, NO,, and THC.

Studies

D.1.3: Major Conclusions Based on Preliminary
Testing

Based on the sampling and analysis results obtained
during the tests, most of the metals detected were more
abundant in the treated soil than in any other sample matrix.
Particulate emissions were well below the RCRA limit of 0.08
grains per dscf. However, the performance of the Retech PCF
did not meet other treatment protocols as described below.

_ The treated slag was leachable and contaminated with
unacceptable levels of organic compounds. It is possible that
the organics in the treated soil were high as a result of raw
feed that inadvertently fell through the reaction chamber into
the slag receiver. Leachability characteristic tests performed
on the waste feed and treated soil samples revealed chromium
to be nonleachable in either the waste feed or the treated soil
and zinc (unregulated) to be leachable in both soil matrices.

The Destruction and Removal Efficiency (DRE) criterion
of 99.99% was not achieved for two of the three TCE samples.
Although 99.99% DRE was achieved for anthracene and
bis(2-ethylhexyl)phthalate, residual concentrations in the
treated soil were greater than 1% of their respective concen-
trations in the feed for these compounds. A significant number
of organic compounds that were not present in the feed were
generated during treatment due to incomplete combustion of
the feed soil contaminants and detected in the stack gas.

The CEM data indicated that process emissions were
promptly affected by disturbances from steady state operation.
Periods of feeding caused CO, CO,, O,, and THC to rise.
During torch outages, the oxygen concentration in the exhaust
gas dropped while all other constituents rose dramatically.
Pouring of the slag also caused the NO, and CO levels to rise
in every case,

A significant amount of copper was detected in all sample
matrices, even though copper was not a spiked compound in
the surrogate waste feed. The abundance of copper found may
be due to breakdown of the plasma torch’s copper electrodes
and from the copper throat of the reactor.

Acceptable treatment results were not obtained during the
Preliminary Tests. Inadequate power input to the system may
have contributed to this. Additional work to address these
problems and develop solutions has been undertaken to deter-

35



Section 4

Economic Analysis

4.1 Introduction

The primary purpose of this economic analysis is to
estimate costs (not including profits) for a commercial-size
treatment utilizing the Retech Plasma Centrifugal Furnace
(PCF) system. The PCF-6 used during the Demonstration Test
is a pilot-scale treatment technology (feed rate of 120 to
200 Ib/hr) and may not be as cost efficient as a full-scale
unit (PCF-8, feed rate of 2,200 lb/hr). The costs associated
with the PCF, as presented in this economic analysis, are
defined by 12 cost categories that reflect typical cleanup
activities encountered on Superfund sites. Each of these cleanup
activities is defined and discussed, forming the basis for the
estimated cost analysis presented in Tables 5 and 6. The costs
presented are based upon installing and operating the PCF at a
fixed facility and treating a total of 2,000 tons of contaminated
waste.

The actual Demonstration Test teated approximately
1,440 _Ib of contaminated soil at a feed rate of 120 Ib/hr and
a weekly prorated on-line percentage of 70% (prorated based
on 2 startups/wk and operating 24 hr/day, 5 days/wk). Typical
on-line conditions of the PCF range from 50% to 70%. With
the feed system used during the Demonstration Tests, the
PCF-6 has reached a maximum feed rate of approximately
200 Ib/hr. By utilizing an improved feed system (such as a
continuous hopper system), a feed rate of 500 Ib/hr is expected.
With such a feeder system, along with a new power supply
and torch, the PCF-6 may reach a feed rate of 1,000 Ib/hr.
Since the PCF-6 used during the Demonstration Tests was
pilot-scale, and therefore was probably not as cost effective as
a full-scale unit, cost calculations were performed for 120,
500, and 1,000 Ib/hr configurations of the pilot-scale PCF-6.
Costs were also estimated for a full-scale PCF-8 (2,200 Ib/hr).
The costs presented in Table 5 are based on:

a feed rate of 500 Ib/hr,

an operating time of 24 hr/day, 5 days/wk, 50 wk/yr,
two starts of the PCF-6 per wk,

50%, 60%, and 70% on-line percentages,

operation of the PCF at a fixed facility, and

treating a total volume of 2,000 tons of waste.

eee eee

The on-line percentage takes into account startup time
and periodic shutdowns to respond to maintenance or opera-
tional problems.

Table 6 shows the costs for a PCF-6 operating with feed
rates of 120, 500, and 1,000 Ib/hr and 50%, 60%, and 70% on-
line conditions. Table 6 also lists the estimated cost of a full-
scale PCF-8 operating at a feed rate of 2,200 Ib/hr and on-line
conditions of 50%, 60%, and 70%. The cost estimates presented
in Table 6 are based on:

an operating time of 24 hr/day, 5 days/wk, 50 wk/ yr,
two starts of the PCF per wk,

operating the PCF at a fixed facility, and

treating a total of 2,000 tons of contaminated waste.

Costs which are assumed to be the obligation of the
responsible party or site owner have been omitted from this
cost estimate and are indicated by a line (—) on Tables 5
and 6. Categories with no costs associated with this technol-
ogy are indicated by a zero (0) on Tables 5 and 6.

Important assumptions regarding operating conditions
and task responsibilities that could significantly impact the
‘cost estimate results are presented below:

+ The cost estimates presented in this analysis are
representative of charges typically assessed to the
client by the vendor and do not include profit. Costs
such as preliminary site preparation, permits and
regulatory requirements, initiation of monitoring
programs, waste disposal, sampling and analyses,
and site cleanup and restoration are considered to be
the responsible party’s (or site owner's) obligation
and are not included in the estimate presented. These
costs tend to be site specific and are left to the reader
to perform the calculations relevant to each specific
case. Whenever possible, applicable information is
provided on these topics so that the reader may
perform the calculations to obtain relevant economic
data.

For hypothetical 100% on-line conditions, the treat-
ment rate is the same as the feed rate of the PCF-6
during the SITE Demonstration Tests; 120 Ib/hr.
Two factors limit the treatment rate: the feed rate and
the on-line percentage. Increasing the feed rate and
the on-line percentage or both greatly reduces the
cost per ton.

17



4.1 Introduction ...
4.2 Results of Economic Analysi:
43 Basis for Economic Analysis
4.3.1 Site and Facility Preparation Costs
43.2 Permitting and Regulatory Costs
4.3.3 Equipment Costs.....
4.3.4 Startup and Fixed Costs...
4.3.5 Labor Costs..
4.3.6 Supplies Costs
4.3.7 Consumables Costs
43.8 Effluent Treatment and Disposal Costs
43.9 Residuals and Waste Shipping, Handling and Transport Costs ..
4.3.10 Analytical Costs
4.3.11 Facility Modification, Repair and Replacement Costs
4.3.12 Site Restoration Costs
44 Future Development of a Transpo
References .....
Appendix A - Process Descriptio:
A.1 Introduction ....
A.2 The Thermal Treatment System
A.3 Exhaust Gas Treatment System
Appendix B - Vendor's Claims ...
B.1 Treatment Effectiveness
B.2 Community Acceptance
B.3 Comparative Economics
B.3.1 Effects of Scale...
B.3.2 Treatment Costs wii
B.3.3. Costs for’ Hazardous Landfill...
B.3.4 Costs for Shredding Plus Kiln Burning Plus Ash Stabilization ..
B.3.5 Summary Statement...
Appendix C. - SITE Demonstration Result
C.1 Toxicity Charactistic Leaching Procedure
C.2 Destruction and Removal Efficiency ..
C.3 Acid Gas Removal and Particulate Emissions
C4 Air Emissions
C.5 Test Soil and T:
C.6 Scrubber Liquor...
C.7 Continuous Emission Monitoring
Appendix D. - Case Studies...
D.1 Preliminary Testin;
D.1.1 Description
D.1.2 Testing Protocol...
D.1.3 Major Conclusions Based on Preliminary Testin;
D.1.4 Data Summary
D.2 MSE Plasma Arc Furna
D.2.1 Description .....
D.2.2 Testing Protocol
D.2.3 Major Conclusions Based on PAFE ACTS ..
D.2.4 Data Summary ..
D.3 Plasmox® Waste Treatment Facility
D.3.1 Description .....
D.3.2. Testing Protocol...
D.3.3 Major Conclusions Based on Plasmox® Waste Treatment Facility
D.3.4 Data Summary
References for Appendices



meaningful because of the low chlorine input. However, it
appears that, even if the chlorine in the feed had been higher,
an HCl removal efficiency of 99% could be achieved.

As shown in Table 3, the particulate emissions during
each of the three Demonstration Tests exceeded the regulatory
limit of 0.08 grains/dscf [40 CFR (07/01/91) §264.343(c)].
These emission rates have not been corrected for 7% oxygen.
The 7% oxygen correction factor is 14/(21-O,%). The oxygen
correction is required by RCRA for all hazardous waste
incinerators except those operating under the condition of
oxygen enrichment. The purpose for correcting for 7% 0, i in
conventional incineration systems is to account for the dilution
factor in the stack gas caused by using excess air for combus-
tion. For the Retech process, pure oxygen is fed to the primary
chamber through an oxygen lance as soon as feeding of the
first batch of soil begins. The O, is continually introduced to
the furnace throughout the remainder of the treatment process.
The O, content of the stack gas when no soil is being fed to the
furnace G.c., between feeding cycles, during recharging of the
feeder) i is in excess of 21%. As stated above, RCRA does not
require the 7% O, correction factor for hazardous waste in-
cinerators operating under oxygen enrichment [40 CFR (07/
01/91) §264.343(c)]. During feeding of the soil to the reactor,
the stack gas O, level drops to approximately 11%. Therefore,
if the correction is to be applied only during the feeding cycle
(when presumably the particulates are being generated), then
the values given in Table 3 should be increased by a factor of
14.

The amount of particulates captured by the air pothution
control system was extremely small. This is demonstrated, in
part, by the low level of scrubber solids present in the sump.
There was less than 0.5% total solids in the scrubber sump
tank, The consequence of the high particulate loading during
the Demonstration Tests was a substantial build-up of par-
ticulate matter in the exhaust blower after the air pollution
control system. The pressure differential across the exhaust
blower was reduced because of the particulate build-up, ‘and
the first two Demonstration Tests were shortened due to this
problem. A larger blower was installed for the third Demon-
stration Test, which was completed as scheduled, but artiou-
late build-up still persisted.

Particulate measurements had not been performed. on the
PCF by MSE, Inc. prior to the Demonstration Tests. ‘The
problem of the high particulate loading in the exhaust blower
had been noticed in previous testing, but not to the extent
found during the Demonstration Tests. The Silver Bow Creek
Superfund Site soil was extremely dry and dusty before it was
mixed with the diesel oil. Even after mixing the soil with the
diesel oil, it was very free-flowing with no standing liquid.
This type of soil had not been treated by the PCF prior to the
Demonstration Tests. It is possible that the fines from |this
feed may not have been retained in the melted soil in the
primary reaction chamber and simply passed through; the
treatment process and the scrubbing unit and into the exhaust
blower and stack gas. If the dust did pass through the treatment
process, it would be expected that a well-designed ;wet
scrubbing system would be capable of capturing the particu-
lates. If the feed soil does not contain any halogenated com-
pounds, then the process does not require a wet scrubbing

system and a baghouse could be used to control the particulate
emissions. Judicious selection of the most suitable air pollu-
tion control device is necessary before implementation of this
technology can be achieved.

3.3.4 Air Emissions

The air emissions during the Demonstration Tests con-
sisted primarily of products of incomplete combustion (PICs)
and Particulates. For the case of the emitted semivolatile
organics, the most dominant compound released in the stack
gas was benzoic acid at an average concentration of approxi-
mately 4 ppm. The occurrence of benzoic acid in the stack gas
is to be expected as both toluene (from the diesel oil) and
chlorine (from the hexachlorobenzene) were present in the
feed soil. These two compounds, with the addition of heat,
readily form benzoic acid as shown in the basic reaction
presented below:

(Toluene) (Benzotrichloride) (Benzoic Acid)
The water and hydroxide required to complete the reaction
were provided by the scrubber.

A group of nitrated compounds was found in the stack
gas at low levels (< 0.3 ppm). These compounds were formed
because of the high levels of NO, and trace quantities of or-
ganic compounds in the stack gas interacting with the scrub-
ber liquor spray. Other compounds such as the phthalate
groups and naphthalene were also present but were found in
the field blanks as well.

In addition to the target compounds identified by the SW-
846 Method 8270 [1] list, the next 20 highest peaks from the
chromatograms were investigated for compound identification
and semi-quantification. A review of the chromatograms and
the spectral data showed that some Tentatively Identified
Compounds (TICs) were present in the gas stream. The first
Demonstration Test yielded a relatively clean chromatogram
that was somewhat comparable to the field blank. No TICs
could be positively identified, but it appeared that some of the
unknowns contained oxygen somewhere in the molecular
structure and some of the unknowns were nitrogen-containing
compounds.

Test 2 data appeared to be notably different from the Test

1 data. The chromatogram indicated that several higher mo-
lecular weight compounds were detected. The TIC data showed
that these compounds were unidentifiable carbonic acids. It
should be noted that there were no positive identifications
made on the specific type of carbonic acid, but the pattern was
present in several of the TICs. Carbonic acids are formed by
Teacting carbon dioxide with water at high temperature. This
may suggest that the torch cooling water leak detected during
Test 3 could have developed during Test 2 (see the Technol-
ogy Evaluation Report for more details). Because of this leak,
Test 3 was aborted early and restarted after the leak had been
repaired. Compounds that eluted in the early stages of the



Appendix A

Process Description

A.1 Introduction

The Plasma Centrifugal Furnace (PCF), developed by
Retech, uses heat generated from a plasma torch to melt and
vitrify solid feed material. Organic components are vaporized
and decomposed by the intense heat of the plasma and are
oxidized by the air used as the plasma gas, before passing to
the off-gas treatment system. Metal-bearing solids are vitrified
into a monolithic nonleachable mass.

The Retech PCF system is comprised of a thermal treat-
ment system and an exhaust gas treatment system, shown
conceptually in Figure A-1. The thermal treatment system
consists of:

a feeder;

a primary chamber;

a plasma torch;

an afterburner;

a secondary chamber; and
a collection chamber.

The exhaust gas treatment system consists of:

a quench tank;

a jet scrubber;

a packed-bed scrubber;
a demister; and

a stack blower.

A.2. The Thermal Treatment System

Hazardous waste is initially loaded manually, from sealed
containers, into a spiral feeder. The waste is fed uniformly and
continuously into the centrifugal reactor through a chute
connecting the feeder to the primary chamber, which is a
Totating tub with a central orifice, or copper throat.

The copper throat, at the bottom of the primary chamber,
is used to strike the arc of the plasma torch. The torch is then
moved slowly up and down the side of the primary chamber
during heat up. Feeding of the waste material begins once the
primary chamber’s temperature is greater than 2,000°F and

Afterburner’

» Secondary Chamber
Collection Chambe

Figure A-1. Schematic of the Plasma Centrifugal Furnace



the secondary chamber’s temperature is greater than 1. :800°F.
Solid material is retained in the tub by centrifugal force: The
primary chamber walls have an inner shell with a water Jacket
welded between. A water/rust inhibitor cooling stream circu-
Tates between the shell and the jacket. At the copper throat, an
area of high heat flux, the cooling water/rust inhibitor flow
area is reduced to increase the cooling in this area. \
The plasma torch uses electrical discharges to add energy
to plasma torch gases in order to increase the gas temperature
beyond that normally attainable by chemical reaction. The
plasma torch produces a transferred arc that directly contacts a
conducting portion (copper throat) of the centrifugal reactor.
The heat generated by the plasma torch brings the waste
material to temperatures sufficient to melt soil (typically on
the order of 3,000°F). The waste is melted by this extreme
heat, incorporating any inorganic and metal components into
a stable material. Organic components are volatilized by the
heat of the plasma and oxidized by the air used as the plasma
gas. Oxygen may also be added from an oxygen lance in the
primary chamber to enhance combustion of organics. |

For this application, the torch uses approximately 20
scfm of air for plasma gas and is rated at 500 kW. It runs on
direct current provided by a power supply that uses 3-phase
input. The torch is cooled by a high velocity flow of distilled
water,

After the feed material adjacent to the copper throat i is
heated to the conducting temperature, the torch is moved
slowly to heat more of the soil on the bottom of the reactor and
eventually the sidewall. As the torch is moved away from the
center of the reactor, the reactor rotation is slowed to allow the
molten soil to run towards the center of the reactor, where it
begins to solidify. This is continued until the entire primary
chamber has been treated by the torch.

Once the complete primary chamber has been treated, the
torch is then used to melt the mass of soil at the copper throat.
When the mass is melted, the reactor spin rate is slowéd to
allow the pool to move inward and the melted soil to pour out
of the bottom of the reactor through the throat, past a natural
gas afterbumer. The afterburner does not operate during the
pouring process,

The afterburner, located just downstream of the primary
chamber, provides an additional heat input (beyond that sup-

plied by the plasma torch) to combust products of incomplete
combustion (PICs). The afterburner operates on a natural gas
flame. The organics that are volatilized and oxidized are
drawn off to the gas treatment system.

A camera port in the secondary chamber allows observa-
tion of the gases and slag exiting the throat. If needed, oxygen
may be added from oxygen jets located in the secondary
chamber to enhance combustion of organics. The secondary
chamber walls have three inches of refractory lining to abate
heat loss and protect the steel walls. These walls also form a
jacketed vessel with cooling water circulating between them
to maintain a safe operating temperature.

The molten mass falls from the secondary chamber into a
heavy pig mold located in the collection chamber. The col-
lection chamber is a cylindrically shaped, water-cooled, jack-
eted vessel. One end is closed off and the other end has a
hinged door, where the pig molds are loaded and unloaded.
Each mold can hold approximately 1,000 Ib of vitrified slag.

A.3 Exhaust Gas Treatment System

Effluent gas treatment equipment is designed to suit
requirements of the feed material. A typical gas treatment
system may consist of: a quench tank, a jet scrubber, a
packed-bed scrubber, and a demister.

A mildly caustic scrubber solution (pH maintained at 8.5)
is used in the quench tank, jet scrubber, and packed-bed
scrubber. The scrubber sump is equipped with a 50-ton chiller
to cool the scrubber water circulating through the exhaust gas
treatment equipment, so that all the moisture can be removed
from the exhaust gases. The chilled scrubber water proceeds
first to the quench tank, where it cools the exhaust gas stream
from approximately 1,000 to 40 °F. From the quench tank, the
scrubber water passes to a jet scrubber, which is designed to
remove particulates and acid gases. A counter-flow packed-
bed scrubber provides additional removal of acid gases. A
demister then removes moisture droplets entrained in the
flow.

The clean gases are emitted to the atmosphere through an
exhaust stack. A stack blower at the exhaust stack maintains a
negative pressure in the reactor system, preventing any leak-
age.





Materials handling requirements for operation of a Re-
tech furnace include containerization and transport to the
process feed, and disposal of the vitrified slag and scrubber
liquor. Retech, Inc. anticipates that the treated soil will meet
delisting requirements and that the slag can be buried in
existing landfills or used as a product (roadfill, ballast, etc.).

3.6 Regulatory Requirements

Operation of the Retech Plasma Centrifugal Furnace for
treatment of contaminated soil requires compliance with cer-
tain Federal, state, and local regulatory standards and guide-
lines. Section 121 of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) re-
quires that, subject to specified exceptions, remedial actions
must be undertaken in compliance with Applicable or Rel-
evant and Appropriate Requirements (ARARs), Federal laws,
and more stringent promulgated state laws (in response to
releases or threats of releases of hazardous substances, pol-
lutants, or contaminants) as necessary to protect human health
and the environment, i

The ARARs which must be followed in treating Super-
fund waste onsite are outlined in the Interim Guidance on
Compliance with ARARs, Federal Register, Vol. 52, (PP
32496 et seq. These are:

+ Performance, Design, or Action-Specific Requirements.
Examples include RCRA incineration standards and
Clean Water Act pretreatment standards for discharge to
Publicly Owned Treatment Works (POTWs). These re-
quirements are triggered by the particular remedial ' ace
tivity selected to clean a site.
Ambient/Chemical-Specific Requirements. These. 1 set
health-risk-based concentration limits based on pollut-
ants and contaminants, e.g., emission limits and ambient
air quality standards. The most stringent ARAR must be
complied with, i
Locational Requirements. These set restrictions on. ac-
tivities because of site location and environs.

Deployment of the Retech system will be affected by
three main levels of regulation:

«Federal EPA air and water pollution regulations,
state air and water pollution regulations, and
local regulations, particularly Air Quality Management
District (AQMD) requirements

.

‘These regulations govern the operation of all technolo-
gics. Other Federal, state, and local regulations are discussed
in detail below as they apply to the performance, emissions,
and residues evaluated from measurements taken during the
Demonstration Tests.

3.6.1 Federal EPA Regulations

3.6.1.1 Clean Air Act

The Clean Air Act (CAA) establishes primary and sec-
ondary ambient air quality standards for protection of public
health, and emission limitations for certain hazardous; air

14

pollutants. Permitting requirements under the Clean Air Act
are administered by each state as part of State Implementation
Plans developed to bring each state into compliance with
National Ambient Air Quality Standards (NAAQS). The am-
bient air quality standards listed for specific pollutants are
applicable to operation of the Retech system due to its poten-
tial emissions, notably CO and NO,, Other regulated emis-
sions may also be produced, depending on the waste feed. It is
likely, then, that a PCF built in any state will be required to
obtain an air permit. The allowable emissions will be estab-
lished on a case-by-case basis depending upon whether or not
the site is in attainment of the NAAQS. If the area is in
attainment, the allowable emission limits may still be cur-
tailed by the available increments under Prevention of Sig-
nificant Deterioration (PSD) regulations. This can only be
determined on a site-by-site basis.

3.6.1.2. Comprehensive Environmental Response,
Compensation, and Liability Act

The Comprehensive Environmental Response, Compen-
sation, and Liability Act (CERCLA) of 1980 as amended by
the Superfund Amendments and Reauthorization Act (SARA)
of 1986 provides for Federal funding to respond to releases of
hazardous substances to air, water, and land. Section 121 of
SARA, entitled Cleanup Standards, states a strong statutory
preference for remedies that are highly reliable and provide
long-term protection. It strongly recommends that remedial
action use onsite treatment that “...permanently and signifi-
cantly reduces the volume, toxicity, or mobility of hazardous
substances.” In addition, general factors which must be ad-
dressed by CERCLA remedial actions are:

long-term effectiveness and permanence,
short-term effectiveness,
implementability, and

cost.

The Retech system has demonstrated that organic con-
taminants in the feed stream can be destroyed with at least
99.99% DRE. This illustrates both long- and short-term ef-
fectiveness with respect to organic compounds. The Plasma
Centrifugal Furnace also demonstrated that heavy metals are
immobilized in a non-leaching vitrified slag based on toxicity
characteristic leaching procedure analyses performed on the
treated soil. The long-term effectiveness and permanence of
the Retech treatment system will not be evaluated by subse-
quent analyses because this is not in the scope of work for this
project. It is anticipated, however, that the components in
treated soil will remain stable in the vitrified slag indefinitely.

The short-term effectiveness of the Retech system may
be evaluated by examining analytical data obtained from the
stack gas and the scrubber liquor. These data indicate that the
Plasma Centrifugal Furnace is effective with respect to some,
but not all, regulated emissions and that the scrubbing system
is not very effective.

The implementability of the system appears favorable.
The assembled system is, however, relatively permanent. This
lack of mobility indicates that the system is better suited for
facilities where ongoing treatment is required rather than for



- Notice

The information in this documenthas been funded by the U.S. Environmental Protection
Agency under Contract No. 68-C0-0048 and the Superfund Innovative Technology
Evaluation (SITE) Program. It has been subjected to the Agency’s peer and administrative
review, and it has been approved for publication as an EPA document. Mention of trade
names or commercial products does not constitute an endorsement or recommendation for
use,



that eluted in the early stages of the chromatogram contained
nitrogen and oxygen within their molecular structures. Test 3
data was very similar to that of Test 1. Generally, only low
levels of semivolatile organic compounds were identified in
the gas stream.

Very low levels of volatile organic compounds were
detected in the exhaust gas stream. The most common of
these compounds was benzene. Other identified compounds
tended to be chlorinated organics which were not present in
the feed soil and therefore can positively be identified as PICs.

No _ polychlorodibenzodioxins (PCDDs) or
polychlorodibenzofurans (PCDFs) were detected above the
blank sample detection limits. This indicates that PCDDs and
PCDFs are not formed by the process when treating a highly
chlorinated feed material. The detection limits for the blank
samples were well within the levels defined by the SW-846
Method 8290.

The metals emissions in the stack gas were almost exclu-
sively in the solid phase. Table C-1 summarizes these results.
The only metals present in significant amounts in the vapor
phase were calcium and mercury. Arsenic, copper, iron, lead,
potassium, and zinc were in abundance in the solid phase in
the stack gas. The air emission data shows that the air
pollution control system did not capture the metals with any
degree of efficiency. This is further displayed by the analysis
of the scrubber water which did not contain high levels of
metals at the conclusion of the tests.

C.5 Test Soil and Treated Slag

The feed soil consisted of a mixture of Silver Bow Creek
Superfund Site soil (a heavy metal-bearing soil) and 10% by
weight No. 2 diesel oil. One thousand ppm of hexachloroben-
zene and 28,000 ppm of zinc oxide (corresponding to 22,500
ppm zinc) were spiked into this mixture. The estimated
means of the organic constituents of the feed are presented in
Table C-2 and are based on all three Demonstration Tests
since the feed soil was homogenized prior to testing. Metals
concentration in the feed soil for all three Demonstration
Tests is presented in Table 4 in Section 3.

Table C-2, Organic Compounds In the Feed Soll

Compound 1b/100 Ib ppm
feed

Volatiles*:

Benzene 9.91E-05 0.99

Ethyl Benzene 2.84E-03 28

Toluene 1.81E-03 18

Xylene 1.34E-02 134

Semivolatiles**:

Hexachlorobenzene 9.72E-05 972

2-Mathylnaphthalene 4.58E-05 458

Naphthalene 1,82E-05 150

Phenanthrene 6.62E-06 66

B Indicates that this compound was detected in a blank.

* — 1,2-Dichloroethane and methyl ethyl ketone were both detected
in small amounts, but not in all sets.

** — Other compounds were detected at low levels, but notin all

sets.

Volatile organic analysis was not performed on the treated
soil as no volatile compounds were considered to exist in the
slag after it had reached its melting point temperature. The
only semivolatile organic compounds found in the treated soil
were low levels of two phthalate compounds. These com-
pounds were likely sampling or analytical contaminants. This
corresponds with the TCLP analysis of the slag discussed
earlier in which no semivolatile compounds leached from the
slag. Table 4 (Section 3) presents the concentration of the
metals in the slag for all three tests. Comparison of these data
to the pre-treatment data show that a large percentage of the
metals from the feed soil were retained within the vitrified
slag. Exceptions to this trend are generally the volatile
metals: arsenic, lead, mercury, and zinc. These volatile
metals have been shown to be exiting the system through the
stack gas. In addition, some of these metals can be found in
the scrubber liquor as shown by Table C-3.

The treated slag (but not the feed soil) was sampled and
analyzed for PCDDs and PCDFs using SW-846 Method 8290.
Again, no PCDDs or PCDFs were found at levels above those
found in the blank samples. It is likely that if all the feed soil
had reached molten temperatures in the furnace, then any
dioxins/furans present in the feed soil would have been ther-
mally destroyed.

C.6 Scrubber Liquor

The pre-test scrubber liquor for each of the three Demon-
stration Tests contained only small amounts of organic com-
pounds. A metals scan of the pre-test scrubber liquor indicated
only low levels of metals as well. Table C-3 summarizes this
information. The only organic compound identified and
accurately quantified was benzoic acid in one of the samples
from Test 2. Other compounds can be identified, but are
present at less than five times the detection limit.

Table C-3 Results of Scrubber Liquor Analysis for Metals

Pre-Test Post-Test

Compound mg/L mg/L
Aluminum 0.89 1.9
Antimony <0.30 <0.30
Arsenic 24 38
Barium 0.45 0.13
Beryllium <0.00050 <0.0050
Cadmium 0.38 0.076
Calcium 71 8.6
Chromium 11 11
Copper 23 44
tron 29 35
Lead 0.98 23
Magnesium 1.4 1.8
Manganese 0.32 0.53
Mercury 0.0075 0.064
Nickel 0.48 0.38
Potassium a 23
Selenium 0.014 0.075

0.026 0.044
Sodium 580 2400
Thallium <0.0016 <0.0016
Vanadium 0.056 0.01f
Zinc 31 100

<  Notdetected at or above the detection limit.

33-



Appendix C

SITE Demonstration Results

This section summarizes the results of the SITE demon-
stration of the Retech Plasma Centrifugal Furnace (PCF)
system as they pertain to the evaluation of the developer’s
claims. These results are further discussed in Section 3 of this
report. A more detailed account of the demonstration is found
in the companion Technology Evaluation Report.

The demonstration activities consisted of three separate
tests using the same feed soil throughout. Sampling of all
process input and output streams was carried out in accordance
with the Demonstration Plan [1].

These test results focus primarily on the leachability
characteristics of the waste along with the Destruction and
Removal Efficiency (DRE) achieved by the technology. Acid
gas removal and particulate emissions, air emissions, con-
tinuous emission monitoring, test soil and treated soil charac-
terization, and scrubber liquor characterization are also
addressed.

C.1 Toxicity Characteristic Leaching
Procedure

The Toxicity Characteristic Leaching Procedure (TCLP)
was performed on both the feed soil and the produced slag.
These results are discussed in detail in Section 3 of this report
and summarized in Table 1. Testing activities indicated that
the process effectively bound inorganic compounds into the
treated soil. TCLP analysis of the feed soil for metals shows
that the only elements exhibiting significant leachability
characteristics during the Demonstration Tests were calcium
and the spiked zinc; therefore, these compounds were selected
as tracer compounds. (Sodium was present, but was not
selected as a tracer compound because it does not behave in
the same manner as other regulated metals.) None of the
TCLP characteristic metals found in the feed soil leachate
were above the regulatory limits.

Both tracer metals, calcium and zinc, showed significant
reduction in leaching properties for the treated soil as compared
to the feed. In fact, all of the metals, with the exception of
aluminum, iron, and sodium showed reduced leachability
characteristics. It is likely that the leachability of aluminum
did not actually change, since the concentration in the leachate
from both the feed and treated soil is low, and the values
reported for the treated soil are only estimates (less than 5

31

times the quantitation limit). The increase in leachability of
iron in the treated soil was due to the utilization of supplemen-
tary steel to aid in the start-up procedures, increasing the iron
content of the feed considerably. Sodium leachability is
discussed in greater detail in Section 3.

Although the feed soil was spiked with high levels of
hexachlorobenzene (1,000 ppm), the only organic constituents
that were found to be leachable from the feed soil were
naphthalene and 2-methylnaphthalene. No organic compounds
were found to leach from the treated slag.

C.2 Destruction and Removal Efficiency

Hexachlorobenzene was spiked into the feed soil at a
level of 1,000 ppm. The DRE (used to determine organic
destruction) was calculated for hexachlorobenzene, the Prin-
cipal Organic Hazardous Compound (POHC), by analyzing
the feed soil and the stack gas for this compound. The estimated
mean level of hexachlorobenzene, based on all the feed soil
samples for the three tests, was 972 ppm. The 95% confidence
interval for the estimated mean was 864 to 1,080 ppm.
Hexachlorobenzene was not detected at all in the stack gas.
DRE calculations were, therefore, based on the stack gas
detection limits from each of the tests.

DREs were also determined for 2-methylnaphthalene, a
semivolatile contaminant, and total xylenes, a group of vola-
tile compounds present in the feed soil. In both cases, DRE
determinations were again based on detection limits since the
compounds were not detected in the stack gas. The estimated
mean level of 2-methylnapthalene in the feed soil was 458
ppm with a 95% confidence interval of 390 to 526 ppm.

For the Demonstration Tests, the estimated average DRE
values for hexachlorobenzene ranged from >99.9968% to
>99.9999%. Table 2 (Section 3) summarizes the DREs for
each test based on the confidence interval of the feed soil and
the detection limit for that particular test. For 2-methylnaph-
thalene, estimated average DREs ranging from >99.9872% to
>99.9996% were attained during the Demonstration Tests.
Total xylenes were present in the feed soil at an estimated
mean level of 134 ppm (95% confidence limit of 128 to 139
ppm). The DREs determined for total xylenes were thus
>99.9929% to >99.9934%. This range represents an average
over all three Demonstration Tests since the detection limit



Section 1

Executive Summary

1.1 Introduction

This report summarizes the findings of an evaluation of
the Plasma Centrifugal Furnace (PCF) developed by Retech,
Incorporated (Retech). The study was conducted under the
Superfund Innovative Technology Evaluation (SITE) Pro-
gram. A series of Demonstration Tests of the technology were
performed by EPA as part of this Program. The results of
these tests, along with supporting data from other testing
performed by the U.S. Department of Energy (DOE) and
other background information, constitute the basis for this
Teport.

The Plasma Centrifugal Furnace is a thermal technology
which uses the heat generated from a plasma torch to treat
metal and organic contaminated waste. This is accomplished
by melting metal-bearing solids and, in the process, thermally
destroying organic contaminants. The molten soil forms a
hard, glass-like non-leachable mass on cooling.

1.2 Conclusions

A number of conclusions may be drawn from the evalua-
tion of this innovative technology. The most extensive data
were obtained during the SITE Demonstration Tests; data
from other testing activities have been evaluated in relation to
SITE Program objectives. The conclusions drawn are:

. The technology can process media contaminated with
both organic and inorganic regulated compounds which
become non-leachable after treatment.

. The Destruction and Removal Efficiency (DRE) of
organic compounds is greater than 99.99%.

. Based on a series of Demonstration Tests, particulate
emissions from the process exceed the RCRA regula-
tory limit of 0.08 grains/dscf.

. NO, concentrations in the stack gas are high, how-
ever, emission rates fall within regulatory limits be-
cause of the low gas stream flow rates.

. A high percentage of the metals from the feed soil are
captured and retained in the vitreous slag. A propor-
tion of the more volatile metals evolve from the feed
and pass through the furnace and the gas scrubbing
system.

. The scrubber used for the Demonstration Tests was
not effectively designed for capture of volatile metal
elements or removal of particulate matter from the
exhaust gas stream.

+ The process can treat a variety of soil and sludge types
and contaminants. The type of feed dictates the selec-
tion of the feeder. Liquids can be processed by feed-
ing the waste through a liquid injection lance.

+ The PCF used during the Demonstration Tests (PCF-
6) is not mobile. Retech estimates that setup time for a
commercial PCF will be approximately 2 months.
This time is required to install, erect, and shakedown
all equipment prior to operation of the system.

+ The present furnace must be erected within an en-
closed facility. Onsite requirements include adequate
power supply, cooling water, and cranes for lifting.

+ The Plasma Centrifugal Furnace is effective for treat-
ing soils contaminated with both metal and organic
compounds. However, the cost of this remediation
technology is high because of the capital cost of the
equipment and the labor requirements. The cost per
ton for this technology is very dependent on the feed
rate of the contaminant to the furnace. For a feed rate
of 500 Ib/hr and an on-line factor of 70%, the cost is
estimated at $1,816/ton; for a feed rate of 2,200 Ib/hr
(70% on-line factor) the cost becomes $757/ton.

1.3 Results

The focus of the Applications Analysis is to assess the
ability of the process to comply with Applicable or Relevant
and Appropriate Requirements (ARARs) and to estimate the
cost of using the technology to remediate a Superfund site.
Where appropriate, ARARs are presented along with the
reported data for comparison. To evaluate this technology, the
leachability characteristics of treated waste along with DREs
achieved by the technology are appraised as part of this report.
Other results regarding acid gas removal and particulate
emissions, air emissions, continuous emission monitoring,
test soil and treated soil characterization, and scrubber liquor
characterization are also addressed. Appendix C presents a
full discussion of the Demonstration Test results and is sup-



Section 2

Introduction

2.1 The SITE Program

In 1986, the EPA’s Office of Solid Waste and Emergency
Response (OSWER) and Office of Research and Develop-
ment (ORD) established the Superfund Innovative Technol-
ogy Evaluation (SITE) program to promote the development
and use of innovative technologies to clean up Superfund sites
across the country. Now in its fifth year, SITE is helping to
provide the treatment technologies necessary to implement
new federal and state cleanup standards aimed at permanent
remedies, rather than quick fixes. The SITE program is com-
posed of three major elements: the Demonstration Program,
the Emerging Technologies Program, and the Measurement
and Monitoring Technologies Program.

The major focus has been on the Demonstration Program,
which is designed to provide engineering and cost data on
selected technologies. To date, the demonstration projects
have not involved funding for technology developers. EPA
and developers participating in the program share the cost of
the demonstration. Developers are responsible for demon-
strating their innovative systems at chosen sites, usually Su-
perfund sites. EPA is responsible for sampling, analyzing, and
evaluating all test results. The result is an assessment of the
technology’s performance, reliability, and cost. This infor-
mation will be used in conjunction with other data to select the
most appropriate technologies for the cleanup of Superfund
Sites.

Developers of innovative technologies apply to the Dem-
onstration Program by responding to EPA’s annual solicita-
tion. EPA will also accept proposals at any time when a
developer has a treatment project scheduled with Superfund
waste. To qualify for the program, a new technology must be
at the pilot or full scale and offer some advantage over
existing technologies. Mobile technologies are of particular
interest to EPA.

Once EPA has accepted a proposal, EPA and the devel-
oper work with the EPA Regional Offices and state agencies
to identify a site containing wastes suitable for testing the
capabilities of the technology. EPA prepares a detailed sam-
pling and analysis plan designed to thoroughly evaluate the
technology and to ensure that the resulting data are reliable.
The duration of a demonstration varies from a few days to
several months, depending on the length of time and quantity
of treated waste needed to assess the technology. After the

completion of a technology demonstration, EPA prepares two
teports, which are explained in more detail below. Ultimately,
the Demonstration Program leads to an analysis of the
technology’s overall applicability to Superfund problems.

The second principal element of the SITE Program is the
Emerging Technologies Program, which fosters the further
investigation and development of treatment technologies that
are still at the laboratory scale. Successful validation of these
technologies could lead to the development of a system ready
for field demonstration. The third component of the site
program, the Measurement and Monitoring Technologies
Program, provides assistance in the development and demon-
stration of innovative technologies to better characterize Su-
perfund sites.

2.2 SITE Program Reports

The analysis of technologies participating in the Demon-
stration Program is contained in two documents: the Tech-
nology Evaluation Report and the Applications Analysis
Report. The Technology Evaluation Report contains a com-
prehensive description of the demonstration sponsored by the
SITE program and its results, It gives a detailed description of
the technology, the site and waste used for the demonstration,
sampling and analysis during the test, the data generated, and
the quality assurance program.

The scope of the Applications Analysis Report is broader
and encompasses estimation of the Superfund applications
and costs of a technology based on all available data. This
report compiles and summarizes the results of the SITE
demonstration, the vendor’s design and test data, and other
laboratory and field applications of the technology. It discusses
the advantages, disadvantages, and limitations of the technol-
ogy.

Costs of the technology for different applications are
estimated in the Applications Analysis Report, based on avail-
able data on pilot- and full-scale applications. The report
discusses the factors, such as site and waste characteristics,
that have a major impact on costs and performance.

The amount of available data for the evaluation of an
innovative technology varies widely. Data may be limited to
laboratory tests on synthetic waste, or may include performance
data on actual wastes treated at the pilot or full scale. In



EPA/540/A5-91/007
June 1992

Retech, Inc., Plasma Centrifugal Furnace

Applications Analysis Report

Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268

& Printed on Recycled Paper



i
terials costs vary with the nature of the waste and the perfor-
mance of the equipment. Maintenance labor has previously
been accounted for under “Labor Costs”. For estimating pur-
poses the annual maintenance materials cost is assumed to be
3% of equipment capital costs. Costs for design adjustments,
facility modifications, and equipment replacements are in-
cluded in the maintenance costs.

4.3.12 Site Restoration Costs

Site cleanup and restoration is limited to the removal of
all excavation equipment from the site. Filling, grading or
recompaction requirements of the soil will vary depending on
the future use of the site and are assumed to be the obligation
of the responsible party. i

4.4 Future Development of a Transportable
PCF

Retech plans to develop a transportable PCF that will be
able to treat hazardous waste onsite, rather than having to
transport the contaminated waste from a hazardous waste site
to the fixed facility of the PCF. The PCF-6 and the PCF-8 are
expected to fit on 5 and 6 transportable trailers, respectively.
This will replace the installation cost of a fixed PCF and the
transportation cost of the waste feed from the site to the fixed
facility of the PCF with: transportation; reassembly; and
disassembly costs of the PCF at each site the furnace is
commissioned to treat contaminated waste. Labor costs for a
transportable PCF would have to include both salaries and
living expenses. Living expenses depend upon several factors:

the duration of the project, the number of local workers hired,
and the geographical location of the project. Depending on the
length of the project, Retech may elect to hire local personnel
and train them to operate the furnace, thus eliminating living
expenses,

The cost of operating a PCF as a transportable technology
would be approximately 30% higher than the cost of operating
the PCF at a fixed facility (if only the costs calculated in this
report are considered). This is an approximate estimate, based.
on treating a total volume of 2,000 tons of waste and a per
diem of $60/day/operator.

References
1. Test Methods for Evaluating Solid Waste, U.S. En-
vironmental Protection Agency. Office of Solid Waste
and Emergency Response. U.S. Government Printing
Office: Washington, D.C., November 1986, SW-
846, Third Edition, Volume IB.

. Douglas, James M. Conceptual Design of Chemical
Processes; McGraw-Hill, Inc.: New York, 1988.

Peters, Max S.; Timmerhaus, Klaus D. Plant Design
and Economics for Chemical Engineers; Third Edi-
tion; McGraw-Hill, Inc.: New York, 1980.

Garrett, Donald E. Chemical Engineering Econom-
ics; Van Nostrand Reinhold: New York, 1989.



temperature, once it stabilized, achieved an average value of
approximately 2,250°F. The afterburner temperature aver-
aged around 1,800°F (slightly higher during Test 3) once the
system reached operating range. The off-gas flowrate was
maintained at approximately 110 scfm during all three Dem-
onstration Tests.

‘The scrubber liquor generated during each of Tests 1 and
2 was close to 150 gal. During Test 3, this value was greatly
exceeded duc to frequent blowdowns of the scrubber in attempt
to reduce particulate loading on the blower downstream.
Nearly 800 gal of scrubber liquor were generated during Test

The PCF-6 is a high maintenance process that is subject
to frequent stoppage because of equipment failure. During the
first Demonstration Test a stoppage occurred when a scrubber
sump pump overheated and tripped the system. The test was
also shortened because of particulate build-up in the exhaust
blower. This same problem caused the second Demonstration
Test to be stopped prior to treatment of all the feed. While
‘warming up the primary chamber for the third Demonstration
Test, the torch developed a cooling water leak. This led to,the
furnace being out of operation for approximately 3 hr while
the leak was repaired. Experience of operating the PCF-6 has
shown that secondary arcing within the primary chamber is
the most common form of equipment breakdown. Torch
cooling water leaks result when this occurs, and the torch ram
need to be welded, plugging these pinhole leaks. With regard
to preventive maintenance, torch electrode replacement is the
most regular of the procedures that need to be carried out to
ensure uninterrupted operation. The electrodes have to, be
replaced every 60 to 100 hr.

‘The plasma torch provides a substantial amount of ther-
mal energy to the feed. However, to protect the equipment
from being damaged by this heat cooling circuits are utilized.
For the PCF-6 the cooling circuits that remove the highest
percentage of the heat from the process are the torch cooling
circuit (31%), the primary chamber cooling circuit (39%), and
the scrubber unit (10%). For optimum operation of the furnace,
it would be anticipated that the majority of the heat removed
from the system would be from the collection chamber and the
scrubbing unit. For the Demonstration Tests, the specific
energy consumption was approximately 8 kWh/Ib. Physical
data indicates that, ideally, a specific energy requirement for
the melting of soils is approximately 0.3 kWh/Ib. Therefore,
there is considerable room for improvement in the design ‘and
operation of the PCF system.

3.4 Ranges of Site Characteristics Suitable for
the Technology

3.4.1 Site Selection

The selection of sites with potential for utilization of the
Retech Plasma Centrifugal Furnace system is not entirely
restricted by the geological features of the site as the equipment
may be erected within the confines of the contaminated area
or placed so that the waste can be transported to the furnace.
Obviously, operation is most cost-effective if the furnace is

erected on-site. The site should be suitable for construction of
a climate controlled building to house the furnace with ap-
propriate access as described below.

3.4.2. Surface, Subsurface, and Clearance
Requirements

Surface requirements for the operation of the Retech
Plasma Centrifugal Furnace include a level, graded area capable
of supporting the equipment and the facility housing this
equipment. Foundations are required to support a weight of
65,500 Ib of furnace, for the PCF-6, in addition to the weight
of the power supply, ancillary equipment, and structural steel.
The weight of the PCF-8 furnace including all ancillary
equipment except the gas clean-up system is 200,000 Ib.

The site must be cleared to allow construction of and
access to the facility. Macadam roads are necessary to provide
support for oversize and heavy equipment.

3.4.3 Topographical Characteristics

Since the treatment process takes place in an enclosed
environment, topographical characteristics of the site need
only be suitable for construction of a facility to house the
furnace and all the ancillary equipment (oxygen tanks, argon
tanks, etc.) In addition, the power requirements for this tech-
nology are substantial (see Section 3.4.7), therefore, the sup-
plying of this electricity has to be taken into consideration.

3.4.4 Site Area Requirements

The site requires sufficient space for a 20-ft X 20-ft
facility to house the PCF-6 furnace. The PCF-8 furnace requires
a20-ft X 30-ft pad. Additionally, space outside of this facility
must be available for storage of any. waste generated during
the treatment process. If mixing of the feed is necessary prior
to treatment, an area onsite for mixing activities is advanta-
geous. The shape of the site is inconsequential to treatment
activities as the furnace can be configured into any position,
the only requirement being that of 30 ft height for the PCF-6
and 45 ft clearance for the PCF-8. The equipment should be
situated in a manner to facilitate convenient access.

3.4.5 Climate Characteristics

Climate characteristics suitable for this treatment tech-
nology cover a broad range, since operation takes place in a
climate controlled facility. Prolonged periods of freezing
conditions may hamper excavation of the contaminated soil.
However, this would not affect the operation of the furnace
itself.

3.4.6 Geological Characteristics

Major geological constraints that can render a site un-
suitable for Plasma Centrifugal Fumace technology include
landslide potential, volcanic activity, and fragile geological
formations that may be disturbed by heavy loads or vibrational
stress,

12





|

mine the potential for the technology to adequately, treat
hazardous waste. Other systems have been confi igured to
include a greater power supply. H

D.1.4 Data Summary

Tables D-1 and D-2 summarize the important results
obtained from the Preliminary Tests. Information is also pro-
vided regarding regulatory limits and restrictions.

The average levels of the contaminants detected in the
treated soil are presented in Table D-1. These contaminants
include those compounds spiked into the feed soil and copper
likely from torch electrodes or the furnace throat, as stated
previously). The levels of organic contaminants in the treated
soil may be higher than anticipated due to the presence of
untreated soil within the treated slag. Leachability character-
istic testing revealed that the amount of zinc that leached from
the treated soil was approximately 0.6% of the total zinc in the
test soil. The chromium values were determined to be insig-
nificant. The relevance of the low chromium values in the
treated soil leachate is diminished by the fact that chromium
‘was not found to be leachable in the feed soil either.

‘The post-treatment scrubber liquor and solids were ana-
lyzed together since insufficient scrubber solids were ob-
tained for independent analysis. Copper and zinc were the
most abundant elements detected. Copper was detected at 720
mg/L in the post-test liquor, compared to 350 mg/L in the pre-
test liquor, while chromium was reported as 3.7 mg/L in the
pre-test and 9.1 mg/L in the post-test. Similarly, zinc was 280
mg/L in the post-test liquor and 160 mg/L in the pre-test. Both
TCE and bis(2-ethylhexyl)phthalate were detected in the
scrubber liquor, but the amounts were each less than their
respective quantitation limit (5 times the detection limit).

The emissions from the stack were analyzed for volatiles,
semivolatiles, metals, particulates, and moisture. For Test 3,
the DREs calculated for the TCE samples were <99.57%,
<99.93%, and 99.9995%. The DREs for the semivolatile
compounds [anthracene and bis(2-ethylhexyl)phthalate] and
particulate concentrations in the stack gas were within federal
regulations (see Table D-2). The most abundant metals in the
stack gas were copper and zinc.

D.2. MSE Plasma Arc Furnace Experiment

D.2.1 Description

During July 1991, prior to the SITE Demonstration Tests,
MSE, Inc. conducted a series of Afterburner Commissioning
Tests (ACTs) as part of their Plasma Arc Furnace Experiment
(PAFE) on Retech’s PCF to evaluate the operation of the
newly installed afterburner and associated chiller [2]. Four
ACTs were planned using identical operating conditions, with
the exception that the feed rate for ACT-1 and ACT-2 was 100
to 300 Ib/hr and the feed rate for ACT-3 and ACT-4 was 120
lb/hr. The feed utilized for these tests was soil obtained from
Idaho National Engineering Laboratories (INEL) mixed with
10% by weight No. 2 diesel fuel. Testing objectives included:

* Monitor upper and lower baffle temperatures to de-
termine optimum operating conditions (with the up-
per baffle thermocouple port and throat camera port
plugged with refractory for ACT-3 and ACT-4.)
Check out afterburner and chiller under actual oper-
ating conditions (and determine automatic controller
setpoints for ACT-3 and ACT-4.)

Personnel training.
Develop operating techniques.

Table D-1. Summary of Test Results and Land Disposal Restrictions*

Scrubber Liquor
{mg/L)

Treated Soil Leachate**
(mg/l)

Treated Soil***
(mg/kg)

Average
Measured
Value

Regulatoly
Limit ©

Paramater

Average
Measured

Average
Measured
Value

Regulatory

Regulatory
Limit Limit

Value

Volatiles:

Tatrachloroathylene 0.056 «

i
ND 0.059 |
0.018 0.28

ND

Bie(2.ethylhoxy/)phthalata

Metals:
Chromium
Copper

Zine

oT
720
280

5.0
1.3
NR

NR 0.001 5.6

NR
NR

—_ 103 4.0
—_ 17 2B
ND

315
21.5

5.0
NR
NR

252
315
893

NR
NR
NR

* — Land disposal restrictions taken from 40 CFR 268.41 and 40 CFR 268.43, November 7, 1986 with documented Federal Register changes

through June 8, 1989.

** During the Proliminary Tests, EP Toxicity analysis was used rather than TCLP analysis. Average measured values reported for Treated
‘Soll Leachata are EP Toxicity values. Compounds with no reported values are not included in the standard EP Toxicity analysis.
Lovels reported are the total concentrations of analytes based on a complete digestion of the treated soil

ND
NR

Not Detected
Not Regulated



It is assumed that preliminary site preparation will be
performed by the responsible party (or site owner). The amount
of preliminary site preparation will depend on the site. ‘Site
preparation responsibilities include site design and layout,
surveys and site logistics, legal searches, access rights. and
roads, preparations for support and decontamination facilities,
utility connections, and auxiliary buildings. Since these costs
are site-specific they are not included as part of the’ site
preparation costs in this estimate.

Additional site preparation requirements peculiar to the
plasma centrifugal reactor are assumed to be performed by the
prime contractor (Retech). These site preparation activities
include excavation of hazardous waste from the contaminated
site and storing the waste in sealed containers prior to treatment
by the furnace.

Cost estimates for site preparation are based on operated
heavy equipment rental costs, labor charges and equipment
fuel costs. It is assumed, to achieve an excavation rate of
approximately nine tons/hr, the minimum rental equipment
required is: three excavators, one box dump truck, and! one
backhoe. An excavator is available for $1,260/wk, a'box
dump truck is available for $525/wk, and a backhoe is avail-
able for $585/wk. The minimum labor required is one super-
visor at $40/hr, three excavator operators at $30/hr each, one
‘box dump truck operator at $30/hr,, and one backhoe operator
at $30/hr. Diesel fuel consumption is estimated at three gal/hr/
excavator, two gal/hr/box dump truck, and three gal/nr/back-
hoe, Diesel fuel prices fluctuate with supply and demand and
current market prices, however, for these calculations it is
assumed to be $1/gal. It is assumed that excavation activities
will operate on a 12 hr/day and a 5 day/wk basis. :

‘Transportation costs of the contaminated waste from the
site to the fixed facility of the PCF are very site- and waste-
specific and have not been included in these cost calculations.

For the purposes of these cost calculations installation
costs are limited to transportation and assembly costs of the
PCF. The installation cost has been annualized based on a 15-
year life of the equipment and a 6% annual interest rate.|The
annualized installation cost is based upon the writeoff of the
total installation cost, using the following equation: '

Annualized
Installation Cost

Where V

i(l+iy
(+p -1

is the cost of installation (assumed to

be limited to transportation and assembly costs),
n isthe equipment life (15 years), and

i is the annual interest rate (6%).

‘Transportation costs are limited to trucking costs. Truck-
ing charges include drivers and are based on a 40,000 Ib, 48-1 ft
long, 8-ft high legal load, Five tractor/trailers are required to
transport the PCF-6 and six trailers are required to transport
the PCF-8, A 1,000 mile basis is assumed at a rate of $1.65/
mile/legal load. i

Assembly consists of unloading the PCF from the trailers,
assembling the furnace, and shakedown testing of the PCF to

check out each of the furnace subsystems individually. As-
sembly costs include laying foundations, installation of
structural steel, piping, wiring, and instrumentation, as well as
other miscellaneous installation tasks. Assembly costs are
assumed to be $250,000. This assumption is based on the
assembly of the PCF-6 at the Component Development and
Integration Facility (CDIF) during spring of 1989.

Utility connections and auxiliary buildings required for
the PCF to operate at a fixed facility can be very expensive,
These costs depend on the fixed facility where the PCF is
installed, and must be considered in site-specific cost calcula-
tions.

4.3.2 Permitting and Regulatory Costs

Permitting and regulatory costs are generally the obliga-
tion of the responsible party (or site owner), not that of the
vendor. These costs may include actual permit costs, system
monitoring requirements, and the development of monitoring
and analytical protocols. Permitting and regulatory costs can
vary greatly because they are site- and waste-specific. No
permitting costs are included in this analysis, however de-
pending on the treatment site, this may be a significant factor
since permitting activities can be very expensive and time-
consuming.

4.3.3, Equipment Costs

Equipment costs include major pieces of equipment (the
plasma centrifugal furnace), purchased support equipment (a
small mobile crane), and rental equipment (none). Support
equipment refers to pieces of purchased equipment necessary
for operation.

The plasma furnace used during the Demonstration Tests
is a pilot- scale unit, with a maximum feed rate of about 200
lb/hr. The equipment cost of this PCF-6 is $1,538,000. Re-
placement of the current scrubber with an improved version,
in order to reduce the volume of scrubber effluent, would add
approximately $400,000 to the equipment cost. To increase
the feed rate to approximately 500 lb/hr a new feeder would
be required. The cost of a larger capacity feeder (500 Ib/nr),
with a hopper for loading waste would be approximately
$100,000. With this new feeder and a new power supply and
torch, it is estimated that the PCF-6 could reach a feed rate of
1,000 Ib/hr. The cost of a new power supply and torch would
be approximately $250,000. For the purposes of these cost
calculations, it is assumed that an improved scrubber is in
place, thus making the cost of a PCF-6 operating at 120, 500,
and 1,000 lb/hr a total of $1,938,000, $2,038,000, and
$2,288,000, respectively. Retech has already developed a
larger furnace that has an estimated feed rate of 2,200 lb/hr
(PCF-8), and an approximate equipment cost of $5,000,000.

The annualized equipment cost is based on a 15-yr life of
the equipment and a 6% annual interest rate. The annualized
equipment cost is based upon the writeoff of the total initial
capital equipment cost and scrap value [2,3] (assumed to be
10% of the original equipment cost) using the following
equation:

20



onsite remediation. A brief cost analysis for treating the same
hypothesized waste at a permanent location, at a Superfund
site with 10,000 tons to treat, and at a Superfund site with
2,000 tons to treat is presented in the paragraphs below. The
waste is assumed to average about 10% of contained organic
by weight.

Assumptions: feed rate is 1 metric tonne/hr (1.1 short
tons/hr), available operating time is six 24-hr days/wk for 50
wk/yr, material treated during 75% of the available operating
time. Power consumption is assumed to be 1,500 kW, 1,200
KW as torch power and 300 kW for auxiliary equipment.
Operations in Switzerland with the PCF-8 indicate that torch
electrodes should be changed at the end of each one week run.

Then, per operating day:

Amount treated - 1.1 X 24 X 0.75 = 19.8 ton

Power at 8/kWh - 1500 X $0.08 X 24 X 0.75 = $2,160
Parts & chemicals - $20 X 24 X 0.75 = 360
Suppl. fuel & oxygen - $40 X 24 X 0.75 = 720
Labor (incl. maint.) at $40/hr - 5 X $40 X24= 4,800

Material handling @ $40/ton = 7190
$8,830
$/ton $446

Capital cost is estimated at $8 X 10° for 5 yr. Payback,
treating each year 19.8 tons X 50 X 6 = 5,940 TPY; the 5 year
output would be 29,700 tons. Thus, for a permanent installa-
tion, the treatment cost would be $446 plus $269 cost of
capital or $715/ton.

To treat 10,000 tons would take 505 operating days or
about 84 weeks. The time to demobilize, transport and re-
install a transportable unit (on 6 or 7 trailers) is estimated at 9
weeks with a dollar outlay of about $300,000. Then the total
cost per ton becomes:

Operating $446
Capital $8 X 10° X (84 + 9)/(250 X 10,000) 298
Setup $300,000/10,000 30

$774

To treat 2,000 tons would only take 101 operating days or
about 17 weeks. The cost is then estimated as:

Operating $446
Capital $8 X 10° X (17 + 9)(250 X 2,000) 416
Setup $300,000/2,000 —150

$1,002

29

The above calculations assume that the capital cost for a
permanent location are comparable with the costs of making
the equipment transportable.

B.3.3 Costs for Hazardous Landfill

As of fall 1991, there still existed at least one landfill
accepting hazardous waste at $800/ton (not including trans-
portation). This might be economically preferred to PCF
treatment for quantities less than 2,000 tons, unless one were
to take into account the risk of having to remove and treat at
some time in the future. If one were to assume the risk to be as
low as 10% and the cost of removal and treatment as $2,000/
ton, the comparative cost would be $1,002 for PCF at 2,000
tons versus $1,100 for hazardous landfill ($800 fee + $100
transportation to fill location + $200 for potential retreatment).

B.3.4 Costs for Shredding Plus Kiln Burning
Plus Ash Stabilization

The PCF-8 can treat drummed waste (which most sites
have a significant amount of), while acceptable kiln treatment
would require shredding. For wastes where the kiln ash does
not pass TCLP requirements, stabilization (making into con-
crete) can be done to meet the requirements, but the stabilized
ash weighs more than the original ash (perhaps twice) and
must still go into a landfill (however at considerably lower
cost than the untreated material). The costs for such a trans-
portable system are rather conjectural. We assume $200/ton
for a shredder cost, $400/ton for the incineration cost and
$150/ton of ash stabilized for stabilization cost. We assume
the cost of admitting the stabilized material to a landfill is
$100/ton of stabilized material (=$200/ton of original ash).
Then the total cost for the alternative treatment would range
from the value for 20% ash (200 + 400 + 0.2 X 350) = $670 to
a value for 80% ash (200 + 400 + 0.8 X 350) = $880.

B.3.5 Summary Statement

The PCF system is least costly only when the subject
material is difficult to treat or when many different types of
material need to be treated by one process. The analysis above
shows that when conventional methods do not provide a final
solution in a one-step process, the PCF system can be less
expensive.

The above statement is in accord with Retech’s customer
contacts. The greatest interest is shown by companies whose
waste problems involve: a) both heavy metals and hard-to-
destroy toxic organics, b) radioactive metals and organics
together, or c) a wide variety of wastes to be treated in one
facility.



facilities where short-term or small-scale treatment is re-
quired,

Based on the Economic Analysis of the Retech PCF
system (see Section 4), the cost of this technology is compara-
tively high with respect to alternative incineration methods.
However, certain types of waste which are not remediable by
other techniques (i.¢., metal and organic contamination, di-
oxin-containing, radioactive) may possibly be rendered
nonhazardous by this technology. Additional testing is re-
quired to evaluate this potential.

3.6.1.3 Resource Conservation and Recovery Act

The Resource Conservation and Recovery Act (RCRA) is
the primary Federal legislation governing hazardous waste
activities. Subtitle “C” of RCRA contains requirements for
generation, transport, treatment, storage, and disposal of haz-
ardous waste, most of which are also applicable to CERCLA
activities.

Depending on the waste feed and the effectiveness of the
treatment process, the Retech system generates two potentially
hazardous waste streams: the scrubber liquor and the treated
slag. For this treatment process with a suitably designed
scrubbing system, the scrubber liquor constitutes the primary
hazardous waste stream. The scrubber liquor contains any
metal contaminants which were volatilized during the treatment
process along with particulate matter removed from the gas
stream,

For generation of any hazardous waste, the site respon-
sible party must obtain an EPA generator identification num-
ber and comply with accumulation and storage requirements
for generators under 40 CFR 262 or have a Part B Treatment,
Storage, and Disposal (TSD) permit of interim status. Com-
pliance with RCRA TSD requirements is required for CERCLA
sites. A hazardous waste manifest must accompany offsite
shipment of waste. Transport must comply with Federal De-
partment of Transportation (DOT) hazardous waste transpor-
tation regulations. The receiving TSD facility must be permitted
and in compliance with RCRA standards.

Technology or treatment standards have been established
for many hazardous wastes; those appropriate for the Retech
process will be determined by the type of waste generated.
The RCRA land disposal restrictions, 40 CFR 268, mandate
that hazardous wastes which do not meet the required treatment
standards receive treatment after removal from a contaminated
site and prior to land disposal, unless a variance is granted. If
either the scrubber liquor or the vitrified slag is a hazardous
waste which does not meet its pertinent treatment standard,
additional treatment will be required prior to land disposal.
Incineration may be the Best Demonstrated Available Treat-
ment (BDAT) prior to disposal of any solid residue in a
certified landfill. Precipitation and/or carbon adsorption may
be necessary for any waste scrubber liquor.

3.6.1.4 Clean Water Act

The Clean Water Act (CWA) regulates direct discharges
to surface water through the National Pollutant Discharge

15

Elimination System (NPDES) regulations. These regulations
require point-source discharges of wastewater to meet estab-
lished water quality standards. Typical operation of the Retech
system does generate liquid discharge streams. Occasionally,
the system cooling water circuits are flushed. It is anticipated
that this cooling water will be discharged into the sanitary
sewer. Discharge of wastewater to the sanitary sewer requires
a discharge permit or, at least, concurrence from state and
local regulatory authorities that the wastewater is in compliance
with regulatory limits. The cooling water may contain rust
inhibitor or other water conditioners at unregulated levels.

3.6.1.5 Safe Drinking Water Act

The Safe Drinking Water Act (SDWA) establishes primary
and secondary national drinking water standards. Provisions
of the Safe Drinking Water Act apply to remediation of
Superfund sites. CERCLA Sections 121(d)(2)(A) and (B)
explicitly mention three kinds of surface water or groundwa-
ter standards with which compliance is potentially required -
Maximum Contaminant Level Goals (MCLGs), Federal Wa-
ter Quality Criteria (FWQC), and Alternate Concentration
Limits (ACLs) where human exposure is to be limited.
CERCLA describes those requirements and how they may be
applied to Superfund remedial actions. The guidance is based
on Federal requirements and policies; more stringent, pro-
mulgated state requirements may result in application of even
stricter standards than those specified in Federal regulations.

3.6.2 State and Local Regulations

Compliance with ARARs may require meeting state
standards that are more stringent than Federal standards or
may be the controlling standards in the case of non-CERCLA
treatment activities. Several types of state and local regula-
tions which may affect operation of the Retech system are
cited below:

* permitting requirements for construction/operation,
prohibitions on emission levels, and
nuisance rules.

3.7 Personnel Issues

3.7.1 Operator Training

Training required for an operator of the Retech system
includes that required by all hazardous waste incinerator
operators plus training specific to the Retech plasma furnace.

The training required of all hazardous waste incinerator
operators is detailed in 40 CFR 264 Subpart B, Section
264.16, Subpart C on preparedness and prevention, as well as
Subpart D on contingency plans and emergency procedures
that also present issues central to personnel training.

Additional operator training, specific to the Retech sys-
tem, is also required. This is necessary in order to develop a
safe and effective operating technique for this unique treat-
ment operation. Use of the plasma torch and high voltage also
demand special operator training.



Acknowledgments

This report was prepared under the direction and coordination of Laurel Staley, EPA

. Superfund Innovative Technology Evaluation (SITE) Program Manager in the RiskReduction

Engineering Laboratory (RREL), Cincinnati, Ohio. Contributors and reviewers for the report

were Kim Lisa Kreiton, Randy Parker, and Robert Stenburg of EPA-RREL, Cincinnati,

Ohio; Ron King and the staff of the U.S. Department of Energy, Technology Development

and Integration Division, Idaho Falls, Idaho; and Dan Battleson, Corry Alsberg, Steve
Kujawa, and the staff of MSE, Inc., Butte, Montana.

This report was prepared for EPA’s SITE Program by the Process Technology Division
of Science Applications International Corporation (SAIC) for the U.S. EPA under Contract
No. 68-C0-0048.

xi



Table D-2. Summary of Stack Gas Results and Regulatory Limits

Average
Measured Regulatory
Parameter Value Limit
Volatiles:
Tetrachloroethylene DRE (%)
Sample 1 <99.57" 99.99
Sample 2 <99.93° 99.99
Sample 3 99.9995 99.99
Semivolatiles:
Anthracene DRE (%) >99.999"" 99.99
Bis(2-ethylhexyl)phthalate DRE (%) 99.998"* 99.99
Emissions:
Particulate (gr/dscf, corrected to 7% O2) 0.041 0.080
Hydrogen Chloride Exiting Stack (Ib/hr) — <0.0005 40
Nitrogen Oxides Exiting Stack (Ib/hr) 1.22" = NR
Nitrogen Oxides Exiting Stack
(lb/hr, corrected to 7% O,) 4270" 9.2

The tetrachloroethylene DREs for Samples 1 and 2 were
determined from stack gas emission rate values that exceeded
the saturation level of the analyses. These values are qualified
with a ‘less than” symbol.

Concentrations of these compounds in the treated soil were
greater than 1% of the concentrations in the feed soil.

The concentration of NO, in the stack gas averaged
approximately 6,500 ppm.

The concentration of NO, in the stack gas (corrected to 7% O,)
averaged approximately 19,250 ppm.

Not Regulated. Regulations apply to emissions corrected to 7%
Oo,

NR

Testing objectives were met for each test.

D.2.2 Testing Protocol

During the Afterburner Commissioning Tests, sampling
and analysis did not take place. Instead, parameters were
monitored periodically by the Data Acquisition System (DAS)
to provide information regarding system operation. CEMs
were also utilized to trace the behavior of the system exhaust
gas. A number of parameters were calculated by the DAS
throughout the tests to provide additional operating informa-
tion. During ACT-3 and ACT-4, the upper baffle thermocouple
port and the throat camera port were plugged with refractory
to assist in raising the secondary combustion chamber tem-
perature. Material was not fed during ACT-3 because of the
unavailability of oxygen, however, testing was conducted to
determine the temperatures that could be achieved in the
secondary chamber.

D.2.3: Major Conclusions Based on PAFE ACTs

During ACT-1, ACT-2, and ACT-4, the afterburner was
utilized to provide additional combustion gas flow. Because
of this, the blower operated at approximately maximum ca-
pacity throughout these three tests. Peak primary chamber
temperatures ranged from 2,287 to 2,334 °F, and peak second-
ary chamber temperatures ranged from 1,778 to 2,241 °F
during ACT-1, ACT-2, and ACT-4. Peak primary chamber
temperature was 2,244°F, and peak secondary chamber tem-
perature was 1,919°F during ACT-3.

37

D.2.4 Data Summary

Figure D-1 shows a typical plot of total hydrocarbons
(THC) during these testing operations. The notable peaks
present represent instances of torch flameout (loss of arc) and
testart. Figure D-2 shows a typical plot of carbon monoxide
(CO). Here again, the peak near the end of treatment coincides
with flameout and restart conditions. Both of these plots
demonstrate low values throughout treatment and effective
combustion of organic compounds.

D.3 Plasmox® Waste Treatment Facility

D.3.1 Description

A hazardous waste treatment facility utilizing a PCF
designed by Retech, Inc. has been constructed in Muttenz,
Switzerland [3]. The facility is devised to treat drummed
waste in a manner minimizing potential exposure to the waste
and to any incompletely burned products, while turning solid
components, including the drum itself into a non-leaching
slag. The Plasmox® facility is owned and operated by MGC
Plasma, Ltd.

The furnace is designated PCF-8 (plasma centrifugal
furnace with an 8-ft diameter primary chamber). The basic
treatment concept is similar to that employed by the PCF-6
during the Demonstration Tests and uses an electric arc in a
sealed, sub-atmospheric environment to vitrify solid constitu-
ents of the feed while organic components are partly burned in
a spinning reaction chamber. The combustibles finish burning
in a secondary combustion chamber. The effluent is cleaned in
a comprehensive gas treatment system, while vitrified material
is periodically tapped into a mold.

The system throughput is about 1 metric ton/hr (usually 4
to 5 drums). Two plasma torches are used for heat input. The
main power is provided with an RP-600T, which uses a power
supply rated at 2,000 amps and 600 volts. This torch is used to
vitrify solid material charged to the rotating tub. A smaller
torch, the RP-250T, is directed at the edge of the throat. It
ensures that no glass is left on the surface of the copper rim of
the throat after material is discharged and adds plasma heat to
the gases entering the secondary combustion chamber.

The burning is accomplished in both the primary cham-
ber and the secondary chamber. Oxygen is added to the
primary chamber through an oxygen lance. Additional air
and/or oxygen is added between the throat and the secondary
combustion chamber to facilitate complete combustion. A
temperature of at least 2,200°F is achieved in the secondary
combustion chamber. Residence time at full flow conditions
is about 2.5 seconds.

The reaction chamber also possesses two liquid injection
lances. During the preheat period, fuel oil is burned to raise
the furnace temperature to 2,200°F before initiating toxic
feed.

A separate building has a comprehensive water treatment
system for cleaning, purifying, and recycling the water which
is used in the quench and ionizing wet scrubbers. At typical



operating conditions, the waste water cleaning plant produces
about 18 kg/hr of filter cake and 4 m*/hr of purified water. The
purified water meets all Swiss standards for discharge into
streams.

D.3.2 Testing Protocol

In order to measure the capacity of the slag to tie up
heavy metals in a non-leaching form, tests were conducted on
March 7, 1991 in which four metals were spiked into the
waste feed. The waste feed was comprised of approximately
175 kg of dirt and 35 kg of steel. The spiked metals included
chromium (17.1 kg), lead (1.9 kg), nickel (0.9 kg), and zinc
(4.0 kg). Operating current in the furnace was 2,000 amps at
600 to 700 volts. Off-gas dust samples were not taken during
this test. The slag generated during this test was chipped from
the furnace and subsequently tested for leach resistance. The

, Swiss standard leach test uses carbon dioxide as the primary
active agent, in contrast to the U.S. TCLP test which uses
acetic acid. The MGC plasma X-ray fluorescence instrument
was used to measure elemental concentrations in the slag.

D.3.3 Major Conclusions Based on Plasmox®
Treatment Facility

The opacity of the off-gas was well under the Swiss
requirement, and emitted NO, averaged about 40 ppm. The
NO, upstream of the deNO, unit ranged from 750 to 900 ppm.
The Swiss requirements for off- '-gas composition were all met.
The leachability characteristics of the slag with respect to the
spiked metals were all within the Swiss regulatory limits.

39

D.3.4 Data Summary

Table D-3 summarizes the results of the analysis of the
slag for the metals spiked into the feed. The Swiss regulatory
limits for these compounds are also provided in this table.
Off-gas composition data collected during these tests was not
available.

Table D-3. Swiss Leach Test Results

Swiss
Compound Test 1 Test 2 Regulatory Limit
(mg/l) (mg/t) (mg/l)
Chromium <0.05 <0.05 0.05
Lead 0.1 <0.1 01
Nickel <0.1 <0.1 0.2
Zine <0.05 0.07 05

References for Appendices

1. Science Applications International Corporation. July 11,
1991. “Demonstration Plan for Centrifugal Plasma Reactor
Technology.”

2. MSE, Inc. July, 1991. “Afterburner Commissioning Tests,
Tests Number ACT-1 through ACT-4.”

3. Fiinfschilling, M. R., W. Bernhard, and R. C. Eschenbach,
“Test Results with the Plasma Centrifugal Furnace at Muttenz,
Switzerland.” Presented at the 1991 Incineration Conference
in Knoxville, Tennessee May 14-16, 1991.



ported by the data presented in the Case Studies in Appéndix

With regard to inorganic compounds, the Demonstra-
tion Test feed soil only exhibited significant leach-
ability characteristics for calcium (175 mg/L) and the
spiked zinc (982 mg/L). Sodium was also present in
the leachate at 1,475 mg/L, but was not selected as a
tracer compound since it behaves differently from
typical metals. None of the TCLP characteristic 'met-
als found in the feed soil were above the regulatory
limit. The treated soil did not exhibit strong leachabil-
ity characteristics for any metals except sodium which
Ieached at approximately the same level as in the feed
soil. Both tracer metals, calcium and zinc, showed
significant reductions in leaching properties as a result
of treatment.

The only organic constituents that were found to be
leachable from the Demonstration Test feed soil were
2-methylnaphthalene and naphthalene. Although the
feed soil was spiked with high levels of
hexachlorobenzene (1,000 ppm), it did not leach from
the soil. No organic compounds were found to leach
from the treated slag.

For the Demonstration Tests, the mean level of
hexachlorobenzene, the Principal Organic Hazardous
Constituent (POHC), based on all the feed soil samples
was 972 ppm. The 95% confidence interval for the
estimated mean was 864 to 1,080 ppm. No hexachlo-
robenzene was detected in the stack gas, therefore, all
DREs determined were based on the detection limit
from each of the tests. For the POHC, hexachloro-
benzene, the average DRE values ranged from
799-9968% to >99.9999% for all the Demonstration
‘ests.

During the three Demonstration Tests, the average
DREs determined for 2-methylnaphthalene ranged
from >99,9939% to >99.99965%.

For total xylenes, the DREs associated with the 95%
confidence interval for all three Demonstration Tests
were >99.9929% to >99.9934%,.

Measured HCI emission rates during the Demonistra-
tion Tests ranged from 0.0007 to 0.00173 Ib/hr. The
HCI removal efficiency of the system was calculated
to be at least 98.5%,

An average of 0.37 grains/dscf of particulate were
emitted in the stack gas throughout the Demonstration
Tests. This exceeds the RCRA regulatory limit of 0.08
grains/dscf, ‘

During the Demonstration Tests, NO, levels were high
(5,000 ppm), however, NO, mass emissions averaged
approximately 2.5 Ib/hr.

The most dominant semivolatile organic compound
released in the stack gas as a product of incomplete
combustion (PIC) during the Demonstration Tests
was benzoic acid. Nitrated compounds were also found
in the stack gas at low levels (<0.3 ppm). Other
oxygenated compounds were detected, but not posi-
tively identified in the stack gas.

The most common volatile organic compound de-
tected (at very low levels) in the Demonstration Test
exhaust gas stream was benzene. Other identified
volatile compounds (PICs) tended to be chlorinated
constituents.

Copper, iron, lead, potassium, and zinc were in abun-
dance in the solid phase in the stack gas emitted
during the Demonstration Tests. The only significant
vapor phase metals were calcium and mercury.

Continuous emission monitoring of the exhaust gases
showed only low levels of total hydrocarbons (<4
ppm) and CO (<2 ppm), thus indicating that efficient
combustion of the organic contaminants was occur-
ting.

The Demonstration Test feed soil contained volatile
compounds consistent with those associated with die-
sel fuel. Volatile organic compound analysis was not
performed on the treated slag. The semivolatile com-
pounds found most predominantly in the feed soil
were the spiked hexachlorobenzene and 2-methyl-
naphthalene. No semivolatile compounds were de-
tected in the treated soil. The metals found most
abundantly in the feed soil were aluminum, calcium,
iron, potassium, sodium, and zinc. Zinc was spiked
into the feed soil at a nominal level of 22,500 ppm. A
high percentage of these elements, except the volatile
metals, were retained in the vitrified slag. The volatile
metals exited the system mainly in the stack gas.

During the Demonstration Tests, the only organic
compound positively identified at a quantifiable level
in the pre-test scrubber liquor was benzoic acid. Addi-
tionally, only low levels of inorganic elements were
present in the pre-test scrubber liquor. The post-test
scrubber liquor did not contain any significant quan-
tities of organic compounds. Nitrated compounds and
phthalates were the only compounds present, but at
Jow levels.