United States
 Environmental Protection
 Agency
EPA/540/SR-94/531
March 1995
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
 Emerging Technology
 Summary

 Bench-Scale Testing of
 Photolysis, Chemical  Oxidation,
 and  Biodegradation of  PCB
 Contaminated  Soils, and
 Photolysis of TCDD
 Contaminated  Soils
   The tests reported herein were con-
 ducted by IT Corporation, Knoxville, TN,
 to investigate the feasibility of a two-
 phase detoxification process that would
 potentially have application to the treat-
 ment of soils contaminated with PCBs
 and 2,3,7,8-tetrachlorodibenzo-p-dioxin
 (TCDD). The first step in the process
 was to degrade the organic contami-
 nants by using ultraviolet (UV) radia-
 tion. The source of UV radiation was
 either artificial UV light or natural sun-
 light, but generally photolytic processes
 are more rapid with artificial UV light.
 Alternatively, advanced oxidation pro-
 cesses, such as iron catalyzed hydro-
 gen peroxide (Fenton's Reagent), were
 used to provide  primary contaminant
 degradation. Both photolysis and
 chemical oxidation  were expected to
 convert contaminants to more easily
 biodegradable compounds. Biological
 degradation, the second step, was then
 used to further destroy organic con-
 taminants and detoxify the soil. Bio-
 degradation is enhanced by the addition
 of microorganisms and nutrients to the
 UV-treated soil.
   The results of bench-scale testing on
 degradation of TCDD by using UV pho-
tolysis, and PCB degradation by using
both UV photolysis and chemical oxi-
dation, indicate that there was no ap-
parent destruction of the dioxin on the
soil, 23% to 69% destruction of PCBs
in UV Tests, and 0% to 53% reduction
in chemical oxidation tests.
  Bioslurry experiments evaluated the
biological reduction of PCB congeners
in surfactant/UV-treated and untreated
soils. Experiments were also conducted
to evaluate the impact of PCB-blodeg-
radation inducers, biphenyl and 4-
bromobiphenyl, on congener removal.
Bioslurry treatment did not provide sig-
nificantly different results for the UV-
treated surface  soil  versus the
untreated soil.
  This Project Summary was developed
by EPA's Risk Reduction Engineering
Laboratory, Cincinnati, OH, to announce
key findings of the SITE emerging tech-
nology that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).

Introduction
  Polychlorinated dioxins, furans, and bi-
phenyls (PCBs) are the  most recalcitrant
                                           Printed on Recycled Paper

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vvEPA
                          United States
                          Environmental Protection
                          Agency
EPA/540/SR-94/531
March 1995
                         SUPERFUND INNOVATIVE
                         TECHNOLOGY EVALUATION
                          Emerging  Technology
                          Summary

                          Bench-Scale Testing of
                          Photolysis,  Chemical  Oxidation,
                          and  Biodegradation  of PCB
                          Contaminated Soils, and
                          Photolysis  of TCDD
                          Contaminated Soils
                           The tests reported herein were con-
                          ducted by IT Corporation, Knoxville, TN,
                          to investigate the feasibility of a two-
                          phase detoxification process that would
                          potentially have application to the treat-
                          ment of soils contaminated with PCBs
                          and 2,3,7,8-tetrachlorodibenzo-p-dioxin
                          (TCDD). The first step in the process
                          was to degrade the organic contami-
                          nants by using  ultraviolet (UV) radia-
                          tion. The source of  UV radiation was
                          either artificial UV light or natural sun-
                          light, but generally photolytic processes
                          are more rapid with  artificial UV light.
                          Alternatively, advanced oxidation pro-
                          cesses, such as iron catalyzed hydro-
                          gen peroxide (Fenton's Reagent), were
                          used to provide primary contaminant
                          degradation. Both  photolysis  and
                          chemical oxidation were expected to
                          convert contaminants to more easily
                          biodegradable compounds. Biological
                          degradation, the second step, was then
                          used to further  destroy organic  con-
                          taminants and detoxify the soil. Bio-
                          degradation is enhanced by the addition
                          of microorganisms and nutrients to the
                          UV-treated soil.
                           The results of bench-scale testing on
                          degradation of TCDD by using UV pho-
tolysis, and PCB degradation by using
both UV photolysis and chemical oxi-
dation, indicate that there was no ap-
parent destruction of the dioxin on the
soil, 23% to 69% destruction of PCBs
in UV Tests, and 0% to 53% reduction
in chemical oxidation tests.
  Bioslurry experiments evaluated the
biological reduction of PCB congeners
in surfactant/UV-treated  and untreated
soils. Experiments were also conducted
to evaluate the impact of PCB-blodeg-
radation inducers, biphenyl and 4-
bromobiphenyl, on congener removal.
Bioslurry treatment did not provide sig-
nificantly different results for the UV-
treated surface  soil  versus  the
untreated soil.
  This Project Summary was developed
by EPA's Risk Reduction Engineering
Laboratory, Cincinnati, OH, to announce
key findings of the SITE emerging tech-
nology that is fully documented in a
separate report of the same title (see
Project Report ordering  information at
back).

Introduction
  Polychlorinated dioxins,  furans, and bi-
phenyls (PCBs) are the most recalcitrant
                                                                   Printed on Recycled Paper

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environmental  contaminants. To  remove
or destroy  contamination on  soils, rela-
tively high-temperature thermal treatment
or harsh chemical treatment is required.
These treatments are  expensive and can
significantly alter  the  composition of the
soil.
  The use  of UV light to destroy dioxins
or RGBs in solutions has long been known.
More recently, the use of UV  light to de-
stroy these compounds  on  soils  was in-
vestigated. Typically, the reaction is aided
by the presence of a solvent or solubiliz-
ing  aid, such  as a surfactant, which  is
transparent to the UV  radiation in the re-
gion  of activity (generally 254 nanometers)
and which has increased solubility for the
contaminants being destroyed. The irra-
diation process can be performed on ex-
cavated soils or in situ with  the use  of
enhanced radiation from lamps or natural
sunlight. The process usually involves the
continued application  of the  solubilizing
aid and continued exposure of fresh sur-
face  to the irradiation source. The solubil-
ity aid helps to transfer the contaminant
from the pores of the soil to  the surface of
soil where the reactions can take place.
The surfactant or solubilizing aid may also
act as a medium for the degradation pro-
cess by providing labile protons to allow
the reaction to proceed more easily.
  Chemical oxidation by Fenton's Reagent
has  been used to destroy  organic com-
pounds  such as formaldehyde, azo dyes,
and  chlorinated phenols in  groundwaters
and  wastewaters. The reaction is ideally
performed at a  pH of 2 to 4 by  using
hydrogen peroxide as the oxidant in the
presence of a ferrous salt. Ferrous ions
catalyze the decomposition of hydrogen
peroxide. In the process of decomposi-
tion,  the reactive  hydroxyl radical is pro-
duced,  and it  is  capable of oxidizing
organic  contaminants.  If, however, the de-
sired oxidation reaction is slow, significant
amounts of hydrogen peroxide can be con-
sumed in unproductive decomposition in-
stead  of  participating  in  the desired
process. Reaction conditions must be es-
tablished to provide useful  rates of con-
taminant oxidation with efficient use  of
hydrogen peroxide reagent.
  Aerobic biodegradation of the lower chlo-
rinated PCB congeners (1 to 3 chlorines)
has  been well documented.  The  more
highly chlorinated congeners are, however,
generally resistant to  microbial attack, al-
though there have been reports of micro-
bial degradation of the higher-chlorinated
PCB congeners (>4 chlorines). Biological
degradation of PCB congeners is highly
affected by the chlorination pattern and
the number of chlorines per  biphenyl. Fur-
ther hindering microbial biodegradation of
PCB is their hydrophobicity, which inhibits
their bioavailability. To increase the rate
and  extent of PCB biodegradation, two
conditions are necessary: the bioavailability
of the PCB should be increased, and the
chlorination level per biphenyl ring should
be decreased. This study  addressed the
bioavailability and microbial attack of PCB
after the combined surfactant/UV  treat-
ment of highly contaminated PCB soil.

Process Description
  This two-phase treatment is envisioned
as a potential in-situ process for shallow
contamination on  soils. More probable,
however, is the use of the technology for
ex-situ on-site treatment of excavated soils
in a specially constructed shallow  treat-
ment basin—one meeting the requirements
of the Resource Conservation and Recov-
ery Act (RCRA). The entire process may
require longer treatment times than other
technologies, but have  a trade off  in
economy. In addition, the only residue gen-
erated from this  combination of technolo-
gies is soil  contaminated with surfactants
and the end metabolites of the biodegra-
dation processes. The end metabolites will
depend on the original contaminants, and
the surfactants are common materials used
in agricultural formulations.

UV  Photolysis Performance
  UV photolysis testing was performed on
three soils,  one  containing  TCDD  con-
tamination and two containing PCB con-
tamination.  The  tests were conducted
independently by using a medium-pres-
sure Hg  lamp, a 10-Hz pulsed lamp and
sunlight, and by employing different sur-
factants and surfactant application proce-
dures. Tests  were carried  out with  either
the 450-watt medium pressure  Hg  lamp
or the 70 watts/in, pulsed lamp operating
approximately 10 in. above the soil with a
parabolic reflector above the lamp.
  A composited  TCDD soil from a Vertac
site in Jacksonville, AR, using two surfac-
tant levels, 2.5% and 5% by weight  of the
dry soil, was tested. TCDD concentrations
on the soil ranged from about 200 to 300
ppb. The soil was mixed and sprayed at
1/2-hr intervals with either surfactant solu-
tion or water for  a total irradiation time of
48 hr.  Results from these  tests  indicated
no apparent destruction of the dioxin on
the soil in any of the tests.
  Surface soil from a Texas  Eastern Gas
Pipeline  site in  Armaugh, PA,  contami-
nated  with  about 10,000  ppm  PCBs
(Aroclor  1248)  and a pit soil  from the
same site containing about 200 ppm  PCBs
were tested  under the  same conditions
given above using different surfactants,
application  procedures,  soil  mixing, etc.
The results of all of the experiments are
summarized in Table 1.

Chemical Oxidation
Performance
  Five batch experiments using the H20,/
Fe (Fenton's) reagent system were done
at ambient temperature. All five  used the
same clay/humic surface soil that was used
in the UV photolysis testing. This soil pro-
vided samples  for treatment that ranged
from 5000 to 10,000 ppm PCBs (Aroclor
1248).  Conditions were established to pro-
vide the best opportunity for observing an
effect due to treatment. Each experimen-
tal mixture was pH adjusted to a pH be-
tween  2 and 4 and continuously stirred.
Hydrogen  peroxide  concentration was
monitored throughout each experiment and
additions were made as necessary to maxi-
mize concentration. Reagent-to-soil ratios
were  high, and Fe concentrations were
varied  between experiments to investigate
the effect. The  treated soil  was  analyzed
either at the end of the treatment time or
sampled at selected times throughout the
run if sufficient soil was used in the test.
Results from testing are summarized  in
Table 2.

Biological Treatment
Performance
  The ability  of  selected  organisms  to
biotransform  PCB congeners in surfac-
tant/UV-treated and  untreated  soil was
evaluated  during  two  bioslurry treatment
experiments. The first bioslurry experiment
evaluated  the biological reduction of PCB
congeners in  surfactant/UV-treated and
untreated  soils. A subsequent enhanced
bioslurry experiment evaluated the impact
of PCB-biodegradation inducers on con-
gener removal. Previous studies show that
the addition of biphenyl, 4-bromobiphenyl
(4-BB), 4-chlorobiphenyl, 2-chlorobiphenyl,
or other monochlorobiphenyls  have in-
duced  and  enhanced  aerobic PCB bio-
degradation.
  The bioslurry experiments were con-
ducted under aerobic conditions at 25°C
using PCB-degrading organisms from two
sources. PCB-degrading  organisms were
isolated from an  impacted  New England
Superfund Site soil (BAG 17). In addition,
known-PCB  degrading microorganisms
were obtained from General Electric Cor-
poration (GE; H850). Three PCB-contami-
nated  soils were  evaluated for biological
reduction  of  PCB congeners. Soils em-
ployed were identified as untreated sur-
face soil from the UV  photolysis testing,
surfactant/UV-treated surface soil, and
New England Superfund Site soil. In sepa-
rate tests, each soil was treated with the
bacteria cultures,  BAG 17  and  H850.  In

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Table 1. Summary ofUV Photolysis Results on PCB Contaminated Soil
Test
1
2
3
4
5
6
7
8
9
10
11
Soil Type
surface
surface
surface
pit
pit
pit
pit
pit
pit
surface
surface
Soil Depth in.
0.25
0.25
0.25
0.5
0.5
0.5
1.0
1.0
1.0
0.25
0.25
Surfactant, %
2
2
2
2
2
2
4.5
2
0
2.5
2.5
Lamp Type
pulsed
medium pressure
pulsed
medium
pressure Hg
medium
pressure Hg
pulsed
pulsed
solar irradiation
solar irradiation
solar irradiation
medium Hg
medium Hg
Temperature
°C
25
28
40
30
28
28
30-40
30-40
30-40


Time (Hr)
12
7
7
16
16
12
25 days
25 days
25 days
20
20
Initial PCB
Cone., ppm
7240
7430
8440
140
157
170
132
159
171
10000
10000
Final PCB
%
Reduction
<15
<15
33
30
13
23
<15
<15
<15
52*
32
'Increase in concentration noted for di-PCBs, decrease in concentration for tetra through hepta-PCBs.
Table 2.  Summary of Chemical Oxidation Testing
Test
1
2
3
4
5
Amount of Soil, g
10
8.0
8.1
170
196
w/surfactant
Water/Soil Ratio
9.7
8.4
9.5
10.1
8.0
pH
2.8
2.5
2.2
3.1
2.9
Fe, % of Soil
2.5
0.1
0.5
.09
.09
H2O2Conc. (%)
Average
.07
1.8
0.87
1.6
0.88
Time (Hr)
162
118
118
845'
184
Percent
Reduction of
Starting PCB
Concentration
44
55
45
35
<,5
'No further decrease in PCB concentration observed after 211 hr.

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addition a killed control sample was pre-
pared for each soil. Table 3 summarizes
the reductions measured for the PCB ho-
mologs after four weeks.
  In the enhanced bioslurry experiment,
the effect of adding 1,000 mg/L biphenyl
inducer and 1,000 mg/L 4-BB  inducer on
PCB biodegradation was investigated. The
BAG  17 culture was used with the New
England Superfund Site soil and  the un-
treated soil because these combinations
demonstrated the highest PCB reductions
in the bioslurry experiment. The soils were
tested with both  inducers. Table  4 sum-
 marizes the reductions measured for the
 PCB homologs after one week.

 Conclusions
   UV photolysis treatment gave  no de-
 tectable decrease in soil TCDD  concen-
 tration in the tests conducted and minimal
 reduction  of  PCBs. The  PCB reductions
 ranged from less than 15% to a maximum
 of 52%  The decreases  in concentration
 were highest for  higher level chlorinated
 PCBs (tetra through hepta-PCBs). In some
 cases greater decreases in concentration
 of lower chlorine level PCBs  were noted.
 These were  suspected to have been lost
 due to volatilization in tests  at increased
 temperatures caused by the heat gener-
  ated by the UV lamp, along with the high
  soil surface area exposed.
    Chemical  oxidation with  Fe catalyzed
  hydrogen peroxide also provided minimal
  reduction of PCBs on the highly contami-
  nated surface soil tested. The PCB con-
  centration reductions ranged from less than
       15% to a maximum of  55%  in reaction
       times of well over 100 hours.  Highest re-
       ductions were observed with higher Fe-to-
       soil ratios and maximized concentrations
       of hydrogen peroxide, up to 2%, by peri-
       odic additions. Where concentrations were
       reduced, the losses of PCBs were ob-
       served more from  the lower chlorinated
       homologs (di and tri-PCBs) and less from
       the  higher  chlorinated homologs  (tetra
       through hepta-PCBs).                .
          Bioslurry treatment did not provide sig-
       nificantly different results for the UV-treated
       surface soil versus the untreated soil. This
       was not surprising since UV treatment was
        not successful  in significantly degrading
        the higher chlorine level  PCB homologs.
        Percent reductions of PCBs were highest
        for  a New England Superfund Site  soil
        that had a significantly  lower concentra-
        tion of  PCB  contamination. The culture
        isolated from the New England soil gave
        70% 20% and 30% reduction of the di,
        tri  and tetra-PCBs, respectively,  in the
         New England soil. PCB reductions less-
         ened with increasing level of chlormation
         with  no significant reduction noted for
         penta, hexa, or hepta-PCBs.  Similar re-
         sults were obtained with inducer additions
         to  the soils. Biphenyl addition gave even
         greater reduction  in PCB concentrations
         for the New  England  site soil with reduc-
         tions of 82%, 54%, 63% and 16% for di,
         tri, tetra, and penta-PCBs, respectively.

         Recommendations
            Although the percent of PCB degrada-
         tion was low, meaningful destruction rates
                                 may have been masked by the high con-
                                 centration of PCBs in the surface soil that
                                 was used in many of these tests. Although
                                 the lower PCB concentration pit soil was
                                 used in some of the photolysis tests with
                                 little difference in results, a more detailed
                                 analysis  of the  processes would be al-
                                 lowed if soils with lower, but still practical
                                 PCB concentrations (<1000 ppm), were
                                 used in this early phase of testing.
                                    High amounts of surfactant were car-
                                 ried  through the treatment  process and
                                 may have been inhibitory to bacterial ac-
                                 tivity or promoted non-PCB degrading ac-
                                 tivity. Likewise, the treated soil had a pH
                                 of 5.5, which may have been inhibitory  to
                                 the bacteria and probably was a result  of
                                  surfactant addition. An additional soil wash-
                                  ing  step may  be necessary to remove/
                                  recycle surfactant from the  soil and neu-
                                  tralize the pH before biological treatment.
                                    In addition, correlations of PCB-degrad-
                                  ing activity with soil type, PCB concentra-
                                  tion  and composition, biphenyl/PCB
                                  concentrations, and bacterial populations
                                  need  to be explored.
                                    Both  of  these processes may  be en-
                                  hanced by adding surfactants to the soil
                                  to solubilize the contaminants and to pro-
                                  vide a medium for reaction mass transfer
                                  processes.                     .
                                    The full report was submitted in fulfill-
                                   ment of Cooperative  Agreement  No.
                                   CR816817-02-0 by IT Corporation under
                                   the sponsorship of the U.S. Environmen-
                                   tal Protection Agency.
   Table 3. Percent Loss of Homolog Groups at Four Weeks Bioslurry Evaluation
   Dichlorobiphenyl

   Trichlorobiphenyl

   Tetrachlorobiphenyl

   Pentachlorobiphenyl

   Hexachlorobiphenyl

   Heptachlorobiphenyl
24

0

0

0

0

0
21

16

 0

 0

 0

 0
                                                                     Untreated Soif
67

 0

 0

 0

 0

 0
0'

0

0

0

0

0
                                                                                                       New England So//0
70

20

30

 0

 0

 0
40

 0

 0

 0

 0

 0
    *Surfactant/UV-treated surface soil - 4000 mg/Kg total PCB.
    "Untreated surface soil - 8400 mg/Kg total PCB.
    'New England Superfund Site soil - 350 mg/Kg total PCB.

    " Segrad^on /ess tnan 15% is not considered significant and is reported as zero..

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