Charles N. Kurucz

Decomposition of aqueous solutions of phenol using high energy electron beam irradiation—A large scale study

High-energy electron-beam irradiation was used to remove phenol from aqueous solution. The variables that affected phenol decomposition were solute concentration, absorbed dose and total alkalinity. Experiments were conducted at large scale (480 L min−1), at solute concentrations of 10.6, 106 and 531 μmol L−1 (1, 10 and 50 mg L−1) over the pH range 5–9, and in the presence and absence of solids (3% w/w kaolin clay). Absorbed doses ranged from 0–7 kGy (0–700 krad). At low absorbed doses, catechol, hydroquinone and resorcinol were identified as the major reaction byproducts. These compounds are consistent with hydroxyl radical (OH·) addition to phenol. Subsequent ring cleavage of hydroxylated phenolic radicals and continued oxidative processes resulted in the formation of formaldehyde, acetaldehyde, glyoxal and formic acid. At high doses only trace amounts of the carbonyl derivatives were observed. Two recirculation experiments were conducted at higher phenol concentrations (≈950 μmol L−1) and it was shown that phenol was removed while the total organic carbon of the solution decreased only slightly. These results suggest that phenol was not mineralized but, rather, that irradiation resulted in the possible formation of higher molecular weight polymers.

The Miami Electron Beam Research Facility: a large scale wastewater treatment application

The Electron Beam Research Facility (EBRF) located in Miami, Florida houses a 1.5 MV, 50 mA electron accelerator. Extensive large scale (460 1 min−1) research on the use of electron beams for the treatment of water and wastewater has been conducted at this facility over the last several years. Initial research focused on determining the disinfection kinetics of bacteria in different wastewater streams at large scale. Our most recent experiments have focused on evaluating the effectiveness of electron beam irradiation in treating industrial wastes and contaminated groundwaters. The latter has been accomplished by dissolving toxic organic compounds of interest in large quantities of potable water (groundwater). The contaminated groundwater simulant is then treated with the electron beam. This paper provides a detailed description of the EBRF, including equipment and layout, experimental protocols used for the research, reliability and maintenance performance estimates based on our operational experience, and treatment cost estimates.

High energy electron beam generation of oxidants for the treatment of benzene and toluene in the presence of radical scavengers

Abstract High energy electron beam irradiation of benzene and toluene in aqueous solution results in their destruction and the formation of highly oxidized reaction byproducts. The product distribution depends upon absorbed dose and pH and results from the reaction of benzene and toluene with the hydroxyl radical (OH.), followed by continued oxidation of intermediate by-products. The dose required to remove 99% (D0.99) of the benzene from solution, at an initial solute concentration of 17.0 μM (1.3 mg l−1), was 95 krad (0.95 kGy, [OH.] ≈ 2.7 × 10−4 M). In the presence of a known radical scavenger, i.e. 3.3 mM methanol, a dose of 1510 krad ( 15.1 kGy, [OH . ] ≈ 4.2 × 10 −3 M ) was required to achieve the same removal. Toluene showed greater removal, in the absence of methanol, than benzene under similar experimental conditions. The D0.99 required to destroy an initial toluene concentration of 47.7 μM (4.4 mg l−1) was 165 krad (1.65 kGy, [OH.] ≈ 4.6 × 10−4 M), whereas the D0.99 for an initial toluene concentration of 16.4 μM (1.5 mg l−1), in the presence of 3.3 mM methanol, was 2074 krad (20.7 kGy, [OH.] ≈ 5.8 × 10−3 M).

Kinetic modeling of carbon tetrachloride, chloroform and methylene chloride removal from aqueous solution using the electron beam process

An innovative treatment process using high energy electrons has been shown to be effective for the destruction of various toxic (regulated) organic chemicals. This paper presents data for the destruction of chlorinated methanes, carbon tetrachloride, chloroform and methylene chloride in treated groundwater. The studies were conducted at pilot scale, using a 75 kW electron beam at a flow rate of 0.38 m3 min−1. This study examined the effect of solute concentration and total alkalinity on removal efficiency. A kinetic model was used to describe the results of single solute experiments of the three chlorinated methanes. These model predictions were then compared to experimental results and showed a varying degree of predictability for the three compounds. These calculations suggest that the initial reactions which eventually lead to the mineralization of the three chlorinated methanes result primarily from aqueous electron initiated reactions. The subsequent reaction between O2 and the carbon centered radicals with the formation of alkyl peroxides also appears important for their ultimate decomposition.

High Energy Electron Beam Irradiation of Water, Wastewater and Sludge

Research on the use of high energy electrons for treating water, wastewater and wastewater sludge has been under way for approximately twenty years. Much of this work has been supported by the National Science Foundation and an overview of that support has been reported on by Bryan.(1) The results of recent work, especially the most recent project at the Miami Electron Beam Research Facility (EBRF), has stimulated great interest in the area of utilizing this technology for treating environmental problems. This facility is located at the Miami Dade Central District (Virginia Key) Wastewater Treatment Plant in Miami, Florida, and is unique in that it is the only electron beam system set up for large scale treatment of wastewater.

Disinfection of wastewaters: high-energy electron vs gamma irradiation

Abstract A study was undertaken to examine the sensitivity of a wastewater population of coliphage, total coliforms and total flora present in raw sewage and secondary effluent after irradiating with similar doses delivered by a high-energy electron beam and y -radiation. The electron beam study was conducted on a large scale at the Virginia Key Wastewater Treatment Plant, Miami, Fla. The facility is equipped with a 1.5 MeV, 50 mA electron accelerator, with a wastewater flow rate of 8 ls −1 . Concurrent y-radiation studies were conducted at laboratory scale using a 5000 Ci, 60 Co y -source. Three logs reduction of all three test organisms were observed at an electron beam dose of 500 krads, while at least four logs reduction were observed at the same dose utilizing the y-source.

Oxidant reduction and biodegradability improvement of paper mill effluent by irradiation

Abstract Paper mill bleach processing wastewaters represent a large input of hazardous compounds to the environment and these compounds are usually non-biodegradable. A preliminary study using a 5000 Ci 60 Co gamma radiation source as a surrogate for electron beam irradiation, potentially an emerging technology for wastewater treatment, to treat a paper mill bleach effluent showed that for an absorbed dose of 800 krads, chemical oxygen demand (COD) was reduced by 13.5% and 5 day biochemical oxygen demand (BOD 5 ) was increased 58.6%. These changes altered the value of COD/BOD 5 from 14 to 5. For the same dose, the absorbable organic halogen (AOX) was reduced 76.2%. These results suggested the possibility of using the electron beam process to detoxify paper mill effluent thereby generating a more biodegradable wastewater.

High energy electron beam irradiation: An innovative process for the treatment of aqueous based organic hazardous wastes

Abstract The use of high energy electrons for the treatment of aqueous solutions appears to be a promising approach in solving the numerous problems associated with contaminated water. Irradiation of aqueous solutions results in the formation of reactive transient species, e– aq, H•, and HO•. In aqueous solutions of toxic and hazardous chemicals, the transient species react with the contaminants resulting in their removal from solution. The study reported in this paper utilizes a pilot plant capable of treating 120 gpm. The accelerating voltage of the electron accelerator is 1.5 MeV with variable current of up to 50 mA. Influent streams of potable water, and raw and secondary wastewater have been used for this study. The compounds studied include halogenated methanes, ethanes, ethenes, benzene and substituted benzenes. Removal efficiencies range from 85 to greater than 99%.

Empirical models for estimating the destruction of toxic organic compounds utilizing electron beam irradiation at full scale

Abstract The Electron Beam Research Facility (EBRF) located in Miami, Florida houses a 1.5 MeV, 50 mA electron accelerator. Extensive large scale (450 1/min) research on the use of electron beams for the treatment of water and wastewater has been conducted at this facility over the last several years. Recent efforts have focused on developing predictive equations for evaluating the effectiveness of electron beam irradiation for treatment of industrial wastes and contaminated groundwaters. This paper develops descriptive empirical models for estimating the removal of selected organic compounds (benzene, toluene, phenol, PCE, TCE and chloroform) by electron beam irradiation as a function of initial contaminant concentration, pH and the presence or absence of suspended materials. Models to estimate the electron dose required to meet specific treatment objectives are also presented. These dose estimates can be used to evaluate the cost of treatment for treatment systems which utilize electron beam accelerators of various voltages, power, and cost.

Large-scale dosimetry using dilute methylene blue dye in aqueous solution

Abstract The radiolytic bleaching of neat aerated methylene blue solutions is relatively stable, when irradiated to doses in the range of 50 to 500 Gy and measured at the main peak of absorption band of the dye (664 nm). The useful range can be extended up to about 5 kGy if the aqueous dye solution contains about 0.1% ethanol by volume and to 10 kGy with 5 % ethanol. By increasing the concentration of the dye in the presence of 5% ethanol doses up to about 30 kGy can be measured. The spectrophotometric readings have to be made during a period of post irradiation stability of 24 hours, after which there is about a 10% increase in absorbance over the next three days due to regeneration of the dye by spontaneous oxidation. Since the industrial grade monovalent dye salt is very inexpensive and is relatively non-toxic, it may be used for dosimetry studies in quality control tests of electron beam processing of large volumes of waste water, when typical doses in the range of 5–30 kGy are required. The influences of dose, dose rate and solute concentration on the bleaching process have been investigated in terms of the decrease of the absorbance of the dye.