United States
Environmental Protection
Agency
EPA/540/M5-92/009
September 1992
&EPA
SUPERFUND INNOmTIVE
TECHNOLOGY EVALUATION
Emerging Technology Bulletin
Electron Beam Treatment for Removal of Trichloroethylene and
Tetrachloroethylene from Streams and Sludge*
Florida International University and the University of Miami
Technology Description: Irradiation of aqueous solutions
with high-energy electrons results in the formation of the aqueous
electron, e~aq, hydrogen radical, H-, and the hydroxyl radical, OH-.
These reactive transient species initiate chemical reactions ca-
pable of destroying organic compounds in aqueous solution, in
most cases oxidizing them to carbon dioxide, water and salt. No
sludge is formed and no pretreatment is necessary. The reaction
by-products are non-toxic and thus this process represents a new
technology for the restoration of contaminated water, soils and
sediments.
At one end of the system, an aqueous solution containing the
hazardous organic chemical(s) is directed over a weir where it
falls in a thin sheet (approximately 4 millimeters thick). At the
other end of the system, a 1.5-million volt insulated core trans-
former (ICT) electron accelerator generates electrons and accel-
erates them to approximately 97% the speed of light. These
* This is the first in a series of bulletins which will report results of research
conducted through this cooperative agreement.
accelerated electrons are propelled in a concentrated beam down
a high-vacuum tube toward a scanner which scans the beam to a
rectangular shape and directs it toward the aqueous solution
which is flowing over the weir. It is at this point, when the
electrons penetrate the waste stream, that treatment occurs. The
studies have been conducted at 120 gal/min, and can be easily
scaled up for larger applications (Figure 1). The process is
essentially pH independent in the range 3-11.
Waste Applicability: This process can treat complex mix-
tures of hazardous chemicals in drinking water, groundwater,
wastewater, and water containing up to 5% suspended solids. It
can be utilized to remove various organic chemicals including
chloroform, bromodichloromethane, dibromochloromethane,
bromoform, carbon tetrachloride, TCE, PCE, frans-1,2-
dichloroethene, c/s-1,2-dichloroethene, 1,1-dichloroethene, 1,2-
dichloroethane, hexachloroethane, 1,1,1-trichloroethane, 1,1,2,2-
tetrachloroethane, hexachloro-1,3-butadiene, methylene chloride,
benzene, toluene, chlorobenzene, ethylbenzene, 1,2-dichloroben-
Vault Exhaust Fan
Window
Exhaust Faif"'
Step-up
Transformei
5-Ton
Crane
V
'o\i
3i
ie Regulator
Capacitor
Bank
Influent Spreade
Scanner
1.5MeV5
mAICT
Electron
Accelerate
Treated Effluent
Samplinq Area
ICT Controls
Influent
Controls
Vault Exhaust Duct
Influent Line
Figure 1. Elevation of the Electron Beam Research Facility, Miami, FL.
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zene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, m-xylene, o-xy-
lene, dieldrin, and phenol.
Test Results: Several different experiments with electron beam
irradiation of aqueous streams were conducted. These experi-
ments had as their focus the effect of water quality, solute con-
centration and irradiation dose on removal efficiency for TCE and
PCE. To develop a more quantitative understanding of the factors
that affect the removal efficiency of TCE and PCE from water by
electron beam, experiments were designed that included the
variables identified as important in the preliminary studies, i.e.
total carbonate alkalinity, bicarbonate/carbonate ion speciation,
solute concentration and the presence and absence of clay. The
water used for the detailed experiments was potable water, and
raw and secondary wastewaters. Potable water is delivered to the
plant with a pH of approximately 9, and an alkalinity of 45 to 60
mg L1 as CaCO3. For these conditions the bicarbonate/carbonate
ion speciation is 7.41 x 10'4M / 4.77 x 10~5 M, respectively. By
lowering the pH of the water, using concentrated HCI, to pH 7, the
speciation is altered to 6.98 x 10'4M / 4.93 x 10~7M. Additional HCI
lowered the pH to 5 and essentially eliminated the carbonate
alkalinity.
To examine the effect of the addition of solids, kaolinite was
added to give a concentration of 3% solids by weight. The addi-
tion of kaolinite resulted in a lowering of pH of the solution to
approximately 7, and therefore only pH 7 and 5 could be directly
compared for the removal of TCE and PCE in the presence and
absence of clay.
In tests to compare the dose required to remove 99% of the TCE
and PCE in three different quality waters at the lower and higher
initial solute concentration, it was apparent that the removal of the
TCE and PCE required a smaller dose in potable water than in
either wastewaters. Although the quality of the three waters were
quite different, there was not a large difference (< two-fold) in the
removal efficiency between the three waters. The removal of PCE
required a higher dose than TCE under equivalent conditions.
This is consistent with the OH- reaction rate constants of the two
compounds.
More detailed studies were conducted at various TCE and PCE
concentrations. The presence of suspended solids up to 3% had
no significant effect on the removal of TCE or PCE when com-
pared to solutions that had no clay. Solute concentration did not
affect removal efficiency at the two lower concentrations studied.
However, higher doses were required to achieve the same re-
moval efficiency when the initial solute concentration approached
10 mg L1).
Reaction by-products were determined for tests containing the
highest concentrations of TCE and PCE. Aldehydes were found
but were at concentrations which accounted for less than 1% of
the total carbon. Formic acid accounted for up to 10% of the
carbon in the TCE and PCE at low doses, but at the higher
doses the percentage conversion resulted in no more than 5% of
the initial solute carbon. The formation of chloroacetic acids in
irradiated solutions of TCE was not observed. Chloride ion mass
balances showed a complete conversion of organic chlorine to
chloride ion.
A paper detailing the results is available and has been submitted
for publication.
For Further Information:
EPA Project Manager
Franklin Alvarez
Office of Research and Development
26 West Martin Luther King Drive
Cincinnati, Oh 45268
(513) 569-7631
Technology Developer Contact:
William J. Cooper
Drinking Water Research Center
VH 326
Florida International University
Miami, FL 33199
(305) 348-3049 FAX (305) 348-3894
Charles N. Kurucz
Departments of Management Science and Industrial Engineering
University of Miami
Coral Gables, FL 33134
(305) 284-6595 FAX (305) 284-2321
Thomas D. Waite
High Voltage Environmental Applications, Inc.
P.O. Box
Miami, FL 33124
(305) 253-9143
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
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