United States
Environmental Protection
Agency
EPA/540/F-93/502
April 1993
©EPA
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Emerging Technology Bulletin
Electron Beam Treatment for the Removal of Benzene and
Toulene from Aqueous Streams and Sludge
Florida International University and the University of Miami
Technology Description: The electron accelerator utilized in
this treatment process has a potential of 1.5 MeV, rated from 0 to
50 mA, providing radiation doses of 0-850 krad (0-8.5 kGy). The
horizontal electron beam is scanned at 200 Hz and impacts the
waste stream as it flows over a weir approximately 1.2 m (48")
wide. The influent streams (460 L min~1, 120 gal min"1 which can
be easily scaled up for larger applications) connected to the
accelerator are potable (drinking) water, secondary wastewater
effluent, and anaerobically digested sewage sludge.
High energy electron beam irradiation of aqueous solutions re-
sults in the following:
H2O -A/ -> 2.7 OH- + 2.6 e-^ + 0.6 H- + 2.6 H3O* + 0.45 H2 + 0.7 H2O2
This process is unique, in comparison to other advanced oxida-
tion processes (AOP), in that it generates equal concentrations of
highly oxidizing (OH«) and highly reducing (e~ ) species. The
reactive transients initiate thousands of chemical reactions ca-
pable of destroying hazardous compounds in aqueous solution,
in most cases, mineralizing them to carbon dioxide, water, and
salt. The process is essentially pH independent in the range 3-
11. No residual sludge is formed and no pretreatment is neces-
sary. The reaction by-products are formed at relatively low con-
centration and are non-toxic. This process, therefore, represents
a new ultimate disposal technology for the remediation of con-
taminated water, soils, and sludge.
Waste Applicability: This process has demonstrated the ability
to treat complex mixtures of hazardous chemicals in drinking
water, groundwater, wastewater, sludge, and water containing up
to 5% w/w suspended solids. It has been shown to be effective in
removing chloroform, bromodichloromethane, dibromo-
chloromethane, bromoform, 1,1,1-trichloroethane, 1,1,2,2-
tetrachloroethane, carbon tetrachloride, TCE, PCE, frans-1,2-
dichloroethene, c/s-1,2-dichloroethene, 1,1-dichloroethene,
hexachloro-1,3-butadiene, hexachloroethane, methylene chloride,
benzene, toluene, phenol, o-, m-, p-xylene, o, m-, p-dichloroben-
zene, chlorobenzene, nitrobenzene, 4-nitrophenol, pentachlorophe-
nol, ethylbenzene, dieldrin, dimethylmethylphosphonate (DMMP),
diethylmethylphosphonate (DEMP), diisopropylmethylphosphonate
(DIMP), acetone, glyoxal, methylglyoxal, acetaldehyde, formalde-
hyde, methylphosphonic acid, acetic acid, o-, m-, p-
dihydroxyphenol, o-cresol, and formic acid.
Test Results: The removal of benzene and toluene from aque-
ous solution has been evaluated as a function of solute concen-
tration, absorbed dose, pH, and total solids content. Table 1
summarizes the doses required to remove 99% (D099) of benzene
and toluene from solution (a dose of 418 krad raises the tem-
perature of the water 1°C). The removal efficiency, D , for
benzene and toluene does not appear to be affected by solution
pH. In addition, 3% w/w Kaolin clay did not appear to significantly
affect the removal efficiency of either benzene or toluene at pH 7
and 5, compared with the absence of Kaolin under similar experi-
mental conditions. Most likely this indicates that the solution
containing 3% w/w solids is essentially transparent to the elec-
tron beam.
Reaction by-products identified for benzene include phenol, 1,2-,
1,3-, and 1,4-dihydroxybenzene, formaldehyde, acetaldehyde, and
glyoxal. The reaction by-products for toluene include, o-cresol,
formaldehyde, acetaldehyde, glyoxal, and methylglyoxal. In all
cases, the sum of the reaction by-products identified, as well as
any unreacted solute, accounted for less than 9% of the total
carbon mass balance for benzene and less than 2% of the total
carbon mass balance for toluene at an absorbed dose of 200
Table 1. Variation of Dosg versus Concentration, pH and Clay Content
for Experiments with Benzene and Toluene
pH
init Do.99
cone krad
mg L-1
init
cone
mg L-1
krad
init Do.99
cone krad
mg L-1
Benzene
5
7
9
5^
7*
0.13
0.10
0.14
0.16
0.15
0.09
0.10
0.09
62
63
48
47
51
65
48
50
1.50
1.88
1.17
1.17
1.67
1.32
1.47
1.22
86
83
39
39
87
95
94
98
6.79
1.82
6.58
1.91
2.22
2.84
1.94
5.96
210
166
211
184
199
231
142
220
Toluene
5
7
9
53
73
0.03
0.04
0.03
0.05
0.04
0.04
0.07
0.07
59
55
57
54
55
58
67
52
0.68
0.63
0.69
0.55
0.83
0.74
0.33
0.42
44
44
95
44
74
89
44
45
3.76
4.86
5.61
6.06
6.11
4.39
3.56
4.28
167
166
166
170
178
165
150
165
aaddition of 3% w/w Kaolin (EPK) clay.
Printed on Recycled Paper
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krad. Presumably the remaining organic carbon is mineralized to
COj and water or to as yet unidentified reaction by-products.
Two papers are available (1 published, 1 submitted for publica-
tion) detailing all experimental results.
For Further Information:
EPA Project Manager
Franklin Alvarez
Risk Reduction Engineering Laboratory
USEPA 26 West Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7631
Technology Developer Contact:
William J, Cooper
Drinking Water Research Center
Florida International University
Miami, FL33191
(305) 348-3049 FAX (305) 348-3894
Charles N. Kurucz
University of Miami
Coral Gables, Ft 33134
(305) 284-6595 FAX (305) 284-2321
Thomas D, Waite
High Voltage Environmental Applications, Inc.
Miami, FL33124
TEL & FAX (305) 253-9143
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
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