&EPA
                               United States
                               Environmental Protection
                               Agency
                          Risk Reduction
                          Engineering Laboratory
                          Cincinnati, OH 45268
Office of
Research and Development
Cincinnati, OH 45268
                                                         EPA/540/S-92/006
                                                   September 1992
Engineering Bulletin
Supercritical  Water
Oxidation
 Technology Status

    Supercritical water oxidation (SCWO) has existed as an
 emerging waste treatment technology for approximately 10
 years [1]. There are currently no full-scale SCWO systems in
 operation, but  considerable bench- and pilot-scale data are
 available. The largest existing SCWO system can process waste
 at a rate of approximately 4 gallons per minute (gpm)[2].

    Several universities and research institutes are studying
 SCWO.  The U.S. Air Force is investigating SCWO for destruc-
 tion of rocket fuels and explosives. The U.S. Department of
 Energy is considering SCWO for treatment of wastes generated
 at its nuclear plants [3].  SCWO is also  being considered by
 National Aeronautics  and Space Administration (NASA) for
 waste treatment during extended space missions [4][5].

    The Defense Advanced Research Projects Agency (DARPA)
 is also investigating SCWO. Ongoing work under a DARPA
 contract includes the design and construction of a mobile
 SCWO  unit for the destruction of military wastes.  General
 Atomics is the prime contractor for this project and the Univer-
 sity of Texas (UT) Balcones Research  Center and Eco Waste
 Technologies (EWT) are subcontractors [6].

    EWT is currently developing a proprietary SCWO system
 which operates above ground (surface  SCWO).  Besides its
 involvement in the DARPA project, EWT is also designing a 5-
 gpm commercial demonstration unit for a small chemical manu-
 facturing facility [6].

    Modell Development Corporation (MODEC) is also devel-
 oping a proprietary surface SCWO system. MODEC hopes to
 have a 5 dry ton/day pilot plant completed in 1992 and small
 commercial units available in 1993 [7].

    MODAR, Inc. owns and operates the 4-gpm SCWO sys-
 tem mentioned previously [2]. MODAR conducts surface SCWO
 research and development in conjunction with its licensor, ABB
 Lummus Crest [8][9].

    GeneSyst International is developing a proprietary SCWO
system called a "Gravity Pressure Vessel" which is designed to
operate below ground (subsurface SCWO) [10].
* [reference number]
                              Vertech was involved in the development of subsurface
                          SCWO reactors, but it was purchased by Wijnanin N.V., which
                          has Air Products and Chemicals as its U.S. licensee. It is not clear
                          whether Wijnanin N.V. or Air Products and Chemicals plans to
                          pursue SCWO development.

                              Oxidyne (previously Vertox) was also involved in subsur-
                          face SCWO development. Oxidyne developed plans for a full-
                          scale, subsurface subcritical water oxidation reactor in Houston,
                          Texas at Sims Bayou Sewage Treatment Plant. Construction of
                          the reactor was initiated but was not completed due to insuffi-
                          cient funding [11][12][13].  Oxidyne is no longer involved in
                          SCWO research and therefore sold a number of its patents and
                          designs to City Management Corporation (CMC). CMC has no
                          immediate plans to continue SCWO research [14]. The Oxidyne
                          work in Houston is important because the design of that sub-
                          critical system may serve as a basis for the design of subsurface
                          systems which operate at supercritical conditions.

                              Research currently being conducted by various firms and
                          universities focuses on a better  understanding of  the SCWO
                          process  and  will be used in the design of full-scale  systems.
                          Specific  research topics include kinetics, the mechanisms of
                          SCWO, and fluid flow characteristics [15][16].
                          Technology Description

                             In SCWO, decomposition occurs in the aqueous  phase
                          above the critical point of water (374°C/221  atmospheres or
                          atm). A schematic of a generic SCWO process is provided in
                          Figure 1. As shown in this figure, the feed stream is typically an
                          aqueous waste.  An oxidant such as air, oxygen, or hydrogen
                          peroxide must be provided unless the waste itself is an oxidant.

                             A supplemental fuel source should also be available.  Be-
                          cause oxidation  is exothermic, SCWO is self-sustaining for a
                          waste stream  with an adequate  chemical oxygen  demand
                          (COD).  According to developers, SCWO is self-sustaining pro-
                          vided the waste stream has a COD of approximately 15,000
                          mg/L or higher [15]. Theoretically, SCWO may be self-sustaining
                          for CODs as low as 5,000 mg/L [10].  At startup and for dilute
                          wastes that will not autogenically sustain combustion, a supple-
                          mental fuel such as waste oil is added [17]. Alternatively, some
                                                                                      Printed on Recycled Paper

-------
                                                      Figure 1
                                                 SCWO Schematic
Aqueous Waste
Supplemental Fuel (opt.)
Oxidant

Supercritical
Water
Oxidation
	 ^ 	 1
^-



Solid/Liquid
Separation





Cooling

-



Depressurization,
Vapor/Liquid
Separation



^ Liquids

dilute wastes can be dewatered until they are concentrated
enough to sustain SCWO without supplemental fuel [18]. Con-
centrated wastes, on the other hand, must be diluted if the
oxidation of the waste will generate more heat than can be
readily removed from the SCWO processing vessel [18].

    The streams entering  an SCWO reactor must be heated
and pressurized to supercritical conditions.  Influent streams are
frequently heated by thermal contact with the hot effluent.
Both influent pressure and backpressure (often a restriction  of
the outlet) must be provided. The influent streams are then
combined at supercritical conditions and oxidation occurs.

    Certain properties of supercritical water make it an excel-
lent medium for oxidation.  Many of the  properties of water
change drastically near its  critical point: the hydrogen bonds
disappear and  water becomes similar to  a moderately polar
solvent; oxygen and almost all hydrocarbons become com-
pletely miscible in water; mass transfer occurs almost instanta-
neously; and the solubility of inorganic salts drops to the parts
per million (ppm) range [19]. Because inorganic salts (as well as
certain other solids) are  nearly insoluble in supercritical water,
solids removal  must be  considered in the design of a SCWO
reactor [7][20][21].

    The  liquid effluent from  SCWO is cooled  (often by heat
exchange with the influent) and returned to ambient pressure.
As the effluent is cooled and depressurized, compounds such
as carbon dioxide and  oxygen will vaporize.  According  to
SCWO developers,  the effluent contains relatively innocuous
products. Organic materials produce carbon dioxide and wa-
ter; additional products depend upon the components of the
waste.  Nitrogen compounds principally produce ammonia
and nitrogen as well as  small amounts  of nitrogen oxides
(NOX); halogens produce the corresponding  halogen acids;
phosphorus produces phosphoric acid; and sulfur  produces
sulfuric acid [18].

    Vendors are currently developing both surface and subsur-
face SCWO systems.  Figure  2 is a schematic of a subsurface
SCWO reactor. As shown in Figure 2, subsurface SCWO reac-
tors will consist of columns of aqueous waste which are deep
enough that the material near the bottom is subjected to a
pressure of at least 221 atm [22]. To achieve this pressure solely
through  hydrostatic head, a water column depth of approxi-
mately 12,000 feet will be required [10]. The  influent and
effluent will flow in opposite directions in concentric vertical
tubes [13].  In  surface SCWO  systems, the majority of the
pressure is provided by a source other than gravity, and the
reactor is on or above the earth's surface.
Applicability

    Surface and subsurface SCWO systems may have slightly
different applications. Because subsurface SCWO systems are
below ground, developers claim that the earth will provide
protection in the event of a catastrophic reactor failure. Subsur-
face designs have additional advantages over surface SCWO
systems, including fewer mechanical parts (which should lead
to lower maintenance) and pressure provided by hydrostatic
head [13].

                        Figure 2
              Subsurface SCWO Reactor
  Influent



A
\
\
\
S
s
s
\
\
\
s
s
\
\
\
\
*v

>

0
k


0

0
>
0



0
0
0 0
0
o
o.
V




T



T
















>



>
'



1



>


>


i


f

t

0


0

Q^

^
0
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o
A
k



0

0
i
h
\f
r
0
o
kc








^




                                           Oxidant
                                              Effluent
'9
\
                                           Downdraft
                                             Reactor
                                                         Engineering Bulletin: Supercritical Water Oxidation

-------
     Surface SCWO systems, however, have several advantages
 over subsurface systems.  Surface systems are  much  more
 accessible (and therefore easier to monitor) than subsurface
 reactors [13]. Developers project that it will not be cost-effec-
 tive to construct subsurface reactors for small waste streams, as
 the drilling cost for the well is significant [10].

     In general, applications of SCWO processes  may include
 liquid wastes, sludges [13], and slurried solid wastes [18]. Po-
 tentially treatable  compounds include  halogenated  and
 nonhalogenated aliphatic and aromatic hydrocarbons; alde-
 hydes; ketones; esters; carbohydrates; organic nitrogen com-
 pounds; polychlorinated biphenyls (PCBs), phenols, and ben-
 zenes; aliphatic and  aromatic alcohols; pathogens and viruses;
 mercaptans, sulfides, and other sulfur-containing compounds;
 dioxins and furans;  leachable metals; and propellant compo-
 nents [12][13][18][22][23]. SCWO has been applied to munici-
 pal and industrial sludges. Tests performed on pulp mill slud-
 ges, for example, showed that SCWO can effectively treat these
 wastes (a total organic carbon destruction  efficiency of 99.3
 percent was achieved).  Further analysis indicated that treat-
 ment of pulp mill sludges by SCWO should be able to compete
 economically with incineration  and, in some  regions, with
 landfilling [7].

     SCWO also compares favorably with wet air oxidation
 (WAO), a commercially available technology which is similar to
 SCWO. In WAO, thermal decomposition and hydrolysis occur
 as well as oxidation.  WAO is conducted in the aqueous phase
 and typically utilizes  temperatures ranging from 150 to 300°C
 and pressures up to 200 atm.  SCWO provides a number of
 advantages over WAO, including higher destruction efficiencies
 (DEs) and lower reaction times [24].  SCWO is also more
 energy-efficient than WAO [25].

    The minimum waste concentration for which  SCWO is
 applicable is waste-specific and can be determined by a cost
 comparison. The costs associated with dewatering the waste,
 operating the SCWO system, and  purchasing  supplemental
 fuel must  be considered.  There is also a  maximum waste
 concentration for which SCWO is applicable because the oxida-
 tion of the waste must  not generate more heat than  can be
 readily removed from the processing vessel [18].  Note, how-
 ever,  that wastes which exceed the maximum concentration
 can be diluted prior to SCWO.  MODAR literature states that its
 SCWO process is most applicable to wastes with hydrocarbon
 concentrations of 1 to 30 percent but it does not specify the
 concentrations of the wastes fed to the SCWO reactor [21 ].

    SCWO developers claim several advantages associated with
 SCWO as a means of destroying wastes:

     •  One vendor plans to design a SCWO system which
        will be transportable and thus applicable to Superfund
        sites [6].
      •  One developer claims that the SCWO process is odor-
        free and extremely quiet [11 ].
     •  According to developers,  SCWO reactions are self-
        sustaining provided the waste stream has a COD of
        approximately  5,000 mg/L or higher [10]. By con-
        trast, self-sustaining incineration requires  a minimum
         COD of approximately 300,000 mg/L [15].
      •  Because SCWO systems operate in a lower tempera-
         ture range (400 to 600°C) than typical incineration
         systems, researchers believe that SCWO will produce
         lower quantities of NO [26].
     Developers claim that SCWO is relatively safe because the
 reaction temperature can be controlled through adjustment of
 the degree of preheating and/or the concentration of the waste
 [7].  The high temperatures and pressures necessary for SCWO
 are potentially dangerous, but designing SCWO reactors with
 large safety factors should  reduce the risk.  One developer
 indicates the failure of a heater tube at approximately 3700 psi
 and 1400°F produced a loud pop and damage to local insula-
 tion, but no injuries and no damage to adjacent equipment or
 instrumentation. The developer further states that fluid  loss
 from the rupture was minimal [6].

     A second danger involves the possibility that the process
 could  be interrupted, causing an incomplete reaction which
 could  produce dangerous offgases.   SCWO systems can be
 designed to provide an emergency shutdown option and  it is
 known that at least one pilot-scale system includes such a
 provision [6]. Note that the above are only potential dangers,
 as no safety problems were documented in the literature re-
 viewed.
 Limitations

    The density of water drops rapidly between 300 and 400°C,
 and SCWO systems typically operate at or above 400°C.  The
 low densities associated with the supercritical temperatures can
 result in the deposition of salts and pyrolytic chars. Deposition
 may result in plugging problems or added cleaning  require-
 ments. Some researchers prefer near-critical water oxidation at
 approximately 300°C, as the density of water is higher and salts
 and chars are more likely to remain dissolved [27].   Other
 developers prefer SCWO and are researching solutions to the
 deposition problem.

    Possible problems due to corrosion must be examined
 when SCWO is considered.  Several studies have been con-
 ducted regarding the minimization of corrosion in SCWO sys-
 tems. Titanium, stainless steel 316, Hastelloy C-276, and Monel
 400 were considered as alternative materials of construction for
 SCWO reactors.  The results of  these studies indicated  that
 titanium had excellent corrosion resistance but its  structural
 properties were unsatisfactory.   Stainless steel 316  exhibited
 adequate corrosion resistance for use at low supercritical tem-
 peratures and moderate pH levels and chloride concentrations;
 a hastelloy (or another nickel-chrome alloy) is recommended
for more corrosive conditions (low pH levels or high chloride
concentrations). The monel had poor corrosion resistance and
 is therefore not recommended for SCWO reactor construction
 [25]. The use of ceramics and ceramic coatings in conjunction
with the above metals has also been proposed [10].

    High-temperature flames which have been observed dur-
ing SCWO may present an additional equipment problem in
both surface and subsurface SCWO systems. Research is being
Engineering Bulletin: Supercritical Water Oxidation

-------
conducted to determine what factors influence these "hydro-
thermal" flames because there is some concern that these
flames will cause "hot spots" which could weaken SCWO ves-
sels [1].

    Other drawbacks associated with SCWO (as well as other
oxidation technologies) include the slow oxidation rate of many
polyhalogenated hydrocarbons and the production of dioxins
from the oxidation of certain halogenated organ ics [27]. The
production of dioxins may not present a significant problem,
however, as the destruction of dioxins by SCWO has  been
documented [7].

    Acetic acid is generally considered one of the most refrac-
tory byproducts of the SCWO of industrial wastes [28]. The
acetic acid  DEs shown in Table 1  reflect a portion  of the
performance data collected on this compound.

    Ammonia, a second refractory compound, is produced by
water oxidation of nitrogen-containing wastes at temperatures
of 300 to 400°C [19].  Water oxidation does not degrade
ammonia at any significant rate at these temperatures.  If a
water oxidation system is to be operated at or below 400°C,
the ammonia  may be removed  by steam stripping or some
other method. Above 425°C, organic nitrogen and ammonia
in an SCWO system will decompose at a significant rate [19].
The primary products of  this decomposition (below 650°C)
are N2  and N2O, which further decompose to form N2 and
02[12].
                                                     Table 1
                                            SCWO Performance Data
Pollutant
1,1,1 - Trichloroethane
1 ,1 ,2,2 - Tetrachloroethylene
1,2- Ethylene dichloride
2,4 - Dichlorophenol
2,4 - Dichlorophenol
2,4 - Dichlorophenol
2,4 - Dichlorophenol
2,4 - Dichlorophenol
2,4 - Dichlorophenol
2,4 - Dimethylphenol
2,4 - Dinitrotoluene
2,4 - Dinitrotoluene
2 - Nitrophenol
2 - Nitrophenol
Acetic acid
Acetic acid
Acetic acid
Acetic acid
Acetic acid
Acetic acid
Activated sludge (COD)
Activated sludge (COD)
Ammonium perchlorate
Biphenyl
Cyclohexane
DDT
Dextrose
Industrial sludge (TCOD)
Methyl ethyl ketone
Nitromethane
Nitromethane
Nitromethane
o - Chlorotoluene
o - Xylene
PCB1234
PCB 1254
Phenol
Phenol
Temp.
(deg. C)
495
495
495
400
400
450
450
500
500
580
410
528
515
530
400
400
450
450
500
500
400
400
500
450
445
505
440
425
505
400
500
580
495
495
510
510
490
535
Pressure
(atm.)









443
443
287
443
430






272
306
374






374
374
374




389
416
DE
99.99
99.99
99.99
,33.7
99.440
63.3
99.950
78.2
>99.995
>99
83
>99
90
>99
3.10
61.8
34.3
92.0
47.4
90.9
90.1
94.1
99.85
99.97
99.97
99.997
99.6
>99.8
99.993
84
>99
>99
99.99
99.93
99.99
99.99
92
>99
React
Time
(min.)
4
4
4
2
1
2
1
2
1
10
3
3
10
15
5
5
5
5
5
5
2
15
0.2
7
7
4
7
20
4
3
0.5
0.2
4
4
4
4
1
10
Oxidant
Oxygen
Oxygen
Oxygen
Oxygen
^2°2
Oxygen
HO2
Oxygen
H,O2
KO2+O
Oxygen
Oxygen
Oxygen
H2°2+°2
Oxygen
H O
Oxygen
KO
Oxygen
H2°2


None
Oxygen
Oxygen
Oxygen
Oxygen
Oxygen
Oxygen
None
None
None
Oxygen
Oxygen
Oxygen
Oxygen
Oxygen
Oxygen
Ref.
13
13
13
13
13
28
28
28
28
29
29
29
29
29
13
13
28
28
28
28
30
30
18
13
13
13
13
19
13
18
18
18
13
13
13
13
29
29
Feed
Cone.
(mg/L)



2,000
2,000
2,000
2,000
2,000
2,000
135
84
180
104
104
2,000
2,000
2,000
2,000
2,000
2,000
62,000
62,000
12,000






10,000
10,000
10,000




1,650
150
                                                       Engineering Bulletin: Supercritical Water Oxidation

-------
 Performance Data

     Significant bench- and pilot-scale SCWO performance data
 are available.  Typical DEs for a number of compounds are
 summarized in Table 1. Although several low DEs are included
 in this table to illustrate the fact that DE is proportional to both
 temperature and residence time, DEs in excess of 99 percent
 can be achieved for nearly all the pollutants studied.

     Studies have been conducted to examine the effects of
 various parameters on SCWO DEs. The operating parameters
 studied include temperature,  residence time, pressure, feed
 concentration, amount of oxidant (as a multiple of stoichiornet-
 ric requirements), and type of oxidant [13][16][28].

    As noted above, DE was found to increase with operating
 temperature and residence time. DE also increases with operat-
 ing pressure, but only slightly [28]. Recent studies also indicate
 that the addition of catalysts such as potassium permanganate,
 manganous sulfate, copper, and iron can enhance DEs [13].

    In at least one study, DE was found to increase slightly with
 feed concentration. The relationship between DE and amount
 of excess oxidant provided has also  been examined.  DE in-
 creases with increasing amounts of oxidant from 100 to 300
 percent of the stoichiometric requirements; adding over 300
 percent of the stoichiometric  amount of oxidant  does not
 significantly affect DEs [16][28].

    Early SCWO systems used either oxygen or air as oxidants.
 Bench-scale studies were conducted to compare the DEs result-
 ing from the use of air and oxygen, but no statistical difference
 was found [13]. In 1987, Welch and Siegwarth developed and
 patented a  variation of SCWO which uses hydrogen peroxide
 as the oxidant. In Welch and Siegwarth's system,  liquid hydro-
 gen peroxide is mixed with  the influent wastewater or slurry
 [13].

    Welch, Siegwarth, and other researchers have shown that
 the use of hydrogen peroxide as an oxidant in SCWO systems
 produced DEs which were significantly higher than those ob-
 tained from the use of air or oxygen for the compounds tested
 [13][28]. Oxidation with hydrogen  peroxide and oxidation
 with oxygen or air proceed by different  mechanisms.  This
 difference may result in higher DEs for either hydrogen perox-
 ide or oxygen depending on the particular organic compounds
 being degraded [28]. Several other factors may influence the
 choice  between oxidants. Hydrogen peroxide is significantly
 more expensive than oxygen but aqueous hydrogen peroxide
 is easier to pump, requires a less expensive feed  system, and
 may be combined with the influent more readily than oxygen
Process Residuals

    In general, residuals from SCWO processes include gases,
liquids, and solids. The gaseous effluent from the bench-scale
treatment of pulp mill sludges was found to primarily consist of
oxygen and carbon dioxide, with small concentrations of nitro-
 gen [7]. Gaseous effluent from the bench-scale treatment of
 propellant components was also analyzed and found to contain
 nitrous oxide (N2O) and oxygen.  Analysis by mass spectros-
 copy did not detect the presence of chlorine (CI2), nitrosyl
 chloride (NOCI), or nitrogen dioxide (NO2). These are positive
 results because they indicate that SCWO avoided the hazard-
 ous products such as CI2 and NOCI formed in typical thermal
 decomposition. In addition, SCWO appears to produce rela-
 tively little NOX [18].

    The aqueous effluent from the SCWO of pulp mill sludge
 had a total organic concentration (TOC) of only 27 ppm. The
 major inorganics present were calcium, chlorine  (as chloride
 ion), nitrogen (as ammonia), sodium, and sulfur (as sulfate).
 The minor elements identified were all present at concentra-
 tions below Environmental Protection Agency (EPA)  ground-
 water pollution criteria [7]. Liquid effluent from the SCWO of
 propellant components contained sodium chloride (NaCI),  ni-
 trite, and nitrate.  The developer believes that the majority of
 the chlorine from the propellant exists as NaCI, but a chlorine
 mass balance has not yet been attempted [18].

    Limited data describing solid residue from SCWO are avail-
 able. When a bench-scale SCWO system was used to treat pulp
 mill sludges, benzene and lead were the only pollutants which
 the toxicity characteristic leaching procedure (TCLP) detected
 at concentrations above EPA groundwater limits. Benzo(a) pyrene
 and PCB, however, had detection limits above the groundwa-
 ter limit. Based on these results, the developer believes that the
 solid residue from SCWO should easily qualify for disposal in
 any sanitary landfill [7]. Before disposal in a sanitary landfill will
 be allowed, however, the residue must be delisted.
Technical Contact

    Technology-specific questions regarding SCWO may be
directed to:

     Dr. Earnest F. Cloyna
     University of Texas at Austin
     Balcones Research Center
     10100BurnetRoad
     Austin, TX 78758
     (512)471-7792

EPA Contact

    Technology-specific questions regarding SCWO may be
directed to:

     Ronald Turner
     U.S. Environmental Protection Agency
     Risk Reduction Engineering Laboratory
     26 West Martin Luther King Drive
     Cincinnati, OH  45268
     (513) 569-7775
Engineering Bulletin: Supercritical Water Oxidation

-------
 Acknowledgments

     This bulletin  was prepared for the U.S.  EPA, Office  of
 Research and Development (ORD), Risk Reduction Engineering
 Laboratory (RREL), Cincinnati, Ohio, by Science Applications
 International Corporation (SAIC) under EPA Contract No. 68-
 C8-0062.  Mr. Ronald Turner served as the  EPA Technical
 Project Monitor. Mr. Thomas Wagner was SAIC's Work Assign-
 ment Manager.   This bulletin was written by Ms.  Sharon
 Krietemeyer of SAIC.
     The following Agency, contractor, and vendor personnel
 have contributed their time and comments by peer reviewing
 the document:

     Mr. Thomas Wagner, SAIC
     Mr. Michael Carolan, City Management Corporation
     Mr. L. Jack Davis, Eco Waste Technologies
     Dr. Earnest F. Cloyna, University of Texas at Austin
     Mr. Glenn T. Hong, MODAR, Inc.
     Mr. James Titmas, GeneSyst International
                                                 REFERENCES
 1.  Supercritical Oxidation Destroys Aqueous Toxic Wastes.
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 2.  Letter from Glenn T. Hong of MODAR, Inc. March 13,
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 3.  New Process Purifies Waste Simply, Safely, Experts Say.
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 4.  Oleson, M., T. Slavin, F. Liening, and R.L. Olson. Con-
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    Physiochemical Waste Management Systems Evaluation.
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 5.  Tester, J.W., G.A. Huff, R.K. Helling, T.B. Thomasson, and
    K.C. Swallow.  Prepared by Massachusetts Institute of
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    Administration, Washington, DC. 1986.

 6.  Letter from L. Jack Davis of Eco Waste Technologies.
    March 27,1992.

 7.  Modell, M. Treatment of Pulp Mill Sludges by
    Supercritical Water Oxidation: Final Report. Prepared for
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 8.  Chemical & Engineering News. Letter to the Editor from
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9.  Chemical & Engineering News. Letter to the Editor from
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 10. Letter from James Titmas of GeneSyst International, Inc.
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 11. Scarlett, H. Hot Water, Pressure Process Can Destroy
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 12. Gloyna, E.F., and K. Johnston. Supercritical Water and
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 13. Adrian, M. A Partial Literature Survey on Supercritical
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    1991.

 14. Letter from Michael Carolan of City Management
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 15. Gloyna, E.F.  Supercritical Water Oxidation, Deep-Well
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    Prepared for the U.S. Environmental Protection Agency,
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    1991.

 16. Wilmanns, E., L. Li, and E.F. Gloyna. Supercritical Water
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 17. Staszak, C, K. Malinowski, and W. Killilea. The Pilot-Scale
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    Environmental Progress.  6(1): 39,1987.

 18. Buelow, S.J., R.B. Dyer, C. K. Refer,  J. H. Atencio, and J. D.
    Wander. Destruction of Propellant  Components in
    Supercritical Water. Submitted to the Workshop on the
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    National Laboratory for the U.S. Department of Energy.
    May 1990.

 19. Shanableh, A. and E.F. Gloyna. Supercritical Water
    Oxidation- -Wastewaters and Sludges. Presented at
    International Association for Water Pollution Research and
    Control Conference, Kyoto, Japan.  August 1990.

20. MODAR Marketing Brochures. Circa 1987.
                                                        Engineering Bulletin: Supercritical Water Oxidation

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 21.  Lawson, M New Technology Tackles Dilute Wastes.
     Chemical Week, October 1986.

 22.  GeneSyst International, Inc.  The Gravity Pressure Vessel.
     June 1990.

 23.  Technology Screening Guide for Treatment of CERCLA
     Soils and Sludges. Office of Solid Waste and Emergency
     Response, Office of Emergency and Remedial Response,
     EPA/540/2-88/004, U.S. Environmental Protection
     Agency, Washington, DC. September 1988.

 24.  Lee, D.S., A. Kanthasamy, and E.F. Gloyna.  Supercritical
     Water Oxidation of Hazardous Organic Compounds.
     Prepared for Presentation at AlChE Annual Meeting,
     November 20-24,1991.

 25.  Matthews,  C.F., and E.F. Gloyna. Corrosion Behavior of
     Three High-Grade Alloys in Supercritical Water Oxidation
     Environments. July 1991.
26. Discussion of Waste Destruction Results (from MODAR
    Marketing Literature).

27. Mill, T. and D. Ross. Effective Treatment of Hazardous
    Waste Under Hydrothermal Conditions.  1991.

28. Lee, D., L. Li, and E.F. Gloyna. Efficiency of H2O2 and O2
    in Supercritical Water Oxidation of 2,4-Dichlorophenol
    and Acetic Acid. Submitted for presentation at AlChE
    Spring  National Meeting, Orlando, Florida, March 18-22,
    1990.

29. Lee, D. and E. F. Gloyna.  Supercritical Water Oxidation -
    a Microreactor System. Presented at WPCF Specialty
    Conference, New Orleans. April 1989.

30. Hartmann, G. et.al.  Water Oxidation of Sludges and
    Toxic Wastes.  Presented at ASCE Conference, Austin
    Texas.  July 1989.
                                                                               'U.S. Government Printing Office: 1992 — 646-080/60037
Engineering Bulletin: Supercritical Water Oxidation

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