Ionizing radiation such as e-beam accelerators (β-rays) and gamma irradiation (γ-rays, 60Co), originally intended for disinfection, is under research for micropollutant degradation. Table 8 lists the facilities in Europe performing wastewater treatment by ionizing radiation.
The gamma irradiation (60Co) dose required for the elimination of estrogen activity below 1 ng L−1 has been found to be about 0.2 kGy (Kimura et al. 2007a (link)). Complete decomposition of DCF (50 mg L−1) in aqueous solutions requires 4.0 kGy (60Co); however, saturation with N2O decreases the dose to 1.0 kGy (Trojanowicz et al. 2012 ). The sterilization dose for DCF sodium salt, as a pharmaceutical raw material, has been found to be 12.4 kGy (60Co) (Ozer et al. 2013 ). Homlok et al. 2011 (link) described complete removal of DCF with 1.0 kGy. When cost is an issue, it is difficult to give a precise price for irradiation systems in advance because of the many factors involved: the kind and amount of pollutants in water, their properties (chemical, biological, etc.), dose-rate to be used, presence of ozone, combined methods of radiation, and conventional techniques. In general, costs decrease with increase of treatment capacity, and it is possible to say that γ-irradiation costs about four times more than e-beam irradiation because of the high cost of 60Co source and the facility (Borrely et al. 1998 (link)).
Major facilities for wastewater treatment by ionizing radiation (Borrely et al. 1998 (link))
| Country | Radiation source | Energy (MeV) | Power (kW)/activity (kCi) | Purpose | Dose (kGy) |
|---|---|---|---|---|---|
| Austria | EBA | 0.5 | 12.5 | TCE, PCE removal | 0.2–2.0 |
| Germany | 60Co | 1.25 | 135 | Disinfection of sludge | 2.0–3.0 |
EBA electron beam accelerator, TCE trichloroethylene, PCE perchloroethylene
The gamma irradiation (60Co) dose required for the elimination of estrogen activity below 1 ng L−1 has been found to be about 0.2 kGy (Kimura et al. 2007a (link)). Complete decomposition of DCF (50 mg L−1) in aqueous solutions requires 4.0 kGy (60Co); however, saturation with N2O decreases the dose to 1.0 kGy (Trojanowicz et al. 2012 ). The sterilization dose for DCF sodium salt, as a pharmaceutical raw material, has been found to be 12.4 kGy (60Co) (Ozer et al. 2013 ). Homlok et al. 2011 (link) described complete removal of DCF with 1.0 kGy. When cost is an issue, it is difficult to give a precise price for irradiation systems in advance because of the many factors involved: the kind and amount of pollutants in water, their properties (chemical, biological, etc.), dose-rate to be used, presence of ozone, combined methods of radiation, and conventional techniques. In general, costs decrease with increase of treatment capacity, and it is possible to say that γ-irradiation costs about four times more than e-beam irradiation because of the high cost of 60Co source and the facility (Borrely et al. 1998 (link)).
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