Technology Description: Irradiation of aqueous solutions

with high-energy electrons results in the formation of the aqueous

electron, eaq

, hydrogen radical, H·, and the hydroxyl radical, OH·.

These reactive transient species initiate chemical reactions capable 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 transformer (ICT) electron accelerator generates electrons and accelerates them to approximately 97% the speed of light. These

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 mixtures 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, trans-1,2-

dichloroethene, cis-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-dichlorobenEmerging Technology Bulletin

Electron Beam Treatment for Removal of Trichloroethylene and

Tetrachloroethylene from Streams and Sludge*

Florida International University and the University of Miami

Vault Exhaust Fan

Window 

Exhaust Fan

5-Ton 

Crane

Voltage Regulator

Step-up 

Transformer

Capacitor 

Bank

Influent Spreader

Scanner

Vault Exhaust Duct

1.5 MeV 50 

mA ICT 

Electron 

Accelerator

Influent Line

Treated Effluent 

Sampling Area

ICT Controls

Influent 

Controls

Trench

Figure 1. Elevation of the Electron Beam Research Facility, Miami, FL.

* This is the first in a series of bulletins which will report results of research

conducted through this cooperative agreement.

United States

Environmental Protection

Agency

EPA/540/M5-92/009

September 1992
zene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, m-xylene, o-xylene, dieldrin, and phenol.

Test Results: Several different experiments with electron beam

irradiation of aqueous streams were conducted. These experiments had as their focus the effect of water quality, solute concentration 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 L-1 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 HCl

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 addition 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 compared 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 removal efficiency when the initial solute concentration approached

10 mg L-1).

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

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EPA

PERMIT No. G-35

United States

Environmental Protection Agency

Center for Environmental Research Information

Cincinnati, OH 45268

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