AOP DEGRADATION OF EMERGING ORGANIC CONTAMINANTS: IONIZING RADIATIONS, ULTRASOUNDS, UV-TIO2 HYBRID TECHNIQUES AND THEIR SCALE-UP

Emerging organic contaminants are becoming a concern because they pass through the regular wastewater treatment plants. Ultraviolet disinfection plants could be easily implemented to advanced oxidation processes by adding appropriate photo-catalysts, enhancing lamp power, and coupling them to ultrasound. Several emerging contaminants (ofloxacin, dicolofenac, carbamazepine, benzophenone-3, benzophenone-4, and triton X-100) among the most frequently detected in the environment have been selected on the base of their chemical characteristics. Lab-scale tests with electron-beam, ultraviolet light (9 W), ultrasounds (37 or 80 kHz and 30 - 120 W), and TiO2 micropearls (10 - 100 mg L-1) have been carried out in order to evaluate cost-benefit of these synergetic techniques. The processes, initiated both by electronbeam and g-rays on ofloxacin or on a multi-component solution, show that pollutants are removed according to a first order process vs. dose. The mineralization process demonstrated to be equally feasible both under fully oxidative (H2O2 present) and under simultaneous oxidative-reductive conditions (no additive), although electron-beam process shows a lesser mineralization efficiency than g-treatment. By controlling dose rate and/or by adding H2O2, the dose was changed over 7 order of magnitude. By using ultrasounds and UVTiO2, the full degradation of the contaminants has been achieved but the mineralization was poor. The energy consumption of ultrasounds does not justify the increasing of the degradation. A 5 L photo-reactor equipped with ultraviolet lamps (144 W), about 0.25 m2 TiO2, and a recycle pump has been built and tested reaching 38% of mineralization in 6 hours.