Is ionizing radiation effective in removing pharmaceuticals from wastewater?

Area of Science:

• Environmental Science
• Water Treatment Technologies
• Chemical Engineering

Background:

• Wastewater effluent is a primary source of water pollution, with pharmaceuticals posing risks due to incomplete removal by conventional treatments.
• Emerging contaminants, including pharmaceuticals, present significant challenges in water quality management.
• Electron beam irradiation (EBI) offers a clean technology for degrading organic compounds and detoxifying pollutants.

Purpose of the Study:

• To assess the efficacy of EBI in degrading aspirin (ASA) and fluoxetine (FLX) in single and mixed solutions.
• To evaluate the impact of EBI on the toxicity of these pharmaceutical contaminants.
• To explore EBI as a potential pre-treatment for wastewater containing pharmaceuticals.

Main Methods:

• Aspirin (ASA) and fluoxetine (FLX) were subjected to electron beam irradiation (EBI) in single and mixed aqueous solutions.
• Degradation percentages were quantified at varying absorbed doses (up to 5.0 kGy).
• Toxicity was assessed using Daphnia similis bioassays to evaluate EBI's impact on contaminant toxicity.

Main Results:

• EBI achieved 98% degradation of single aspirin at 5.0 kGy.
• Aspirin's toxicity to Daphnia similis increased with absorbed dose, likely due to H2O2 and oxidation byproducts.
• Complete degradation of both ASA and FLX was observed in the irradiated mixture.
• Toxicity removal for the pharmaceutical mixture ranged from 56.2% to 58.8% at 1.0 and 2.5 kGy, respectively.

Conclusions:

• EBI is effective in degrading pharmaceuticals like aspirin and fluoxetine in wastewater.
• While EBI degrades contaminants, byproduct formation can transiently increase toxicity.
• EBI shows potential as a pre-treatment method, enhancing the effectiveness of subsequent biological wastewater treatment.