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 results in the following:

H2O -/ \ / -> 2.7 OH• + 2.6 eaq + 0.6 H• + 2.6 H3O+ + 0.45 H2 + 0.7 H2O2

This process is unique, in comparison to other advanced oxidation processes (AOP), in that it generates equal concentrations of

highly oxidizing (OH•) and highly reducing (eaq

) species. The

reactive transients initiate thousands of chemical reactions capable 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 necessary. The reaction by-products are formed at relatively low concentration and are non-toxic. This process, therefore, represents

a new ultimate disposal technology for the remediation of contaminated 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, dibromochloromethane, bromoform, 1,1,1-trichloroethane, 1,1,2,2-

tetrachloroethane, carbon tetrachloride, TCE, PCE, trans-1,2-

dichloroethene, cis-1,2-dichloroethene, 1,1-dichloroethene,

hexachloro-1,3-butadiene, hexachloroethane, methylene chloride,

benzene, toluene, phenol, o-, m-, p-xylene, o-, m-, p-dichlorobenzene, chlorobenzene, nitrobenzene, 4-nitrophenol, pentachlorophenol, ethylbenzene, dieldrin, dimethylmethylphosphonate (DMMP),

diethylmethylphosphonate (DEMP), diisopropylmethylphosphonate

(DIMP), acetone, glyoxal, methylglyoxal, acetaldehyde, formaldehyde, methylphosphonic acid, acetic acid, o-, m-, pdihydroxyphenol, o-cresol, and formic acid.

Test Results: The removal of benzene and toluene from aqueous solution has been evaluated as a function of solute concentration, absorbed dose, pH, and total solids content. Table 1

summarizes the doses required to remove 99% (D0.99) of benzene

and toluene from solution (a dose of 418 krad raises the temperature of the water 1oC). The removal efficiency, D0.99, 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 experimental conditions. Most likely this indicates that the solution

containing 3% w/w solids is essentially transparent to the electron 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

EPA/540/F-93/502

April 1993

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

United States

Environmental Protection

Agency

Table 1. Variation of D0.99 versus Concentration, pH and Clay Content

for Experiments with Benzene and Toluene

pH init D0.99 init D0.99 init D0.99

conc krad conc krad conc krad

mg L-1 mg L-1 mg L-1

Benzene

5 0.13 62 1.50 86 6.79 210

0.10 63 1.88 83 1.82 166

7 0.14 48 1.17 39 6.58 211

0.16 47 1.17 39 1.91 184

9 0.15 51 1.67 87 2.22 199

0.09 65 1.32 95 2.84 231

5a 0.10 48 1.47 94 1.94 142

7a 0.09 50 1.22 98 5.96 220

Toluene

5 0.03 59 0.68 44 3.76 167

0.04 55 0.63 44 4.86 166

7 0.03 57 0.69 95 5.61 166

0.05 54 0.55 44 6.06 170

9 0.04 55 0.83 74 6.11 178

0.04 58 0.74 89 4.39 165

5a 0.07 67 0.33 44 3.56 150

7a 0.07 52 0.42 45 4.28 165

aaddition of 3% w/w Kaolin (EPK) clay.
BULK RATE

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EPA/540/F-93/502

krad. Presumably the remaining organic carbon is mineralized to

CO2

 and water or to as yet unidentified reaction by-products.

Two papers are available (1 published, 1 submitted for publication) 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, FL 33199

(305) 348-3049 FAX (305) 348-3894

Charles N. Kurucz

University of Miami

Coral Gables, FL 33134

(305) 284-6595 FAX (305) 284-2321

Thomas D. Waite

High Voltage Environmental Applications, Inc.

Miami, FL 33124

TEL & FAX (305) 253-9143