Pilot-scale assessment of the viability of UVA radiation for H2O2 or S2O82− activation in advanced oxidation processes

International audience ; UVA and UVC radiation were compared for the activation of H2O2 or S2O82− to remove micropollutants remaining in treated wastewater with a view to optimising the cost and/or the efficiency of the commonly studied UVC/H2O2 process. Experiments were carried out in a dynamic laboratory pilot (20 L). In a simple matrix, UVA radiation were able to produce oxydative radicals from H2O2 or S2O82−, although faster degradation of the estrogens was observed under UVC radiation (up to 55-fold). With both UV radiation, S2O82− was photolyzed faster than H2O2, resulting in faster estrogen degradation (up to 12-fold). Coupling UVA to H2O2 was considered not to be viable because <4 % of the compounds were degraded at 1000 mJ cm−2. In a treated wastewater, estrogen degradations were inhibited due to organic matter and stronger inhibitions were observed with S2O82− processes (up to 80 % inhibition compared to simple matrix). The UVC/S2O82−-process still achieved the fastest degradation rate, but is roughly comparable to the UVC/H2O2-process. Very low degradation rates obtained with UVA/S2O82− limit the interest in the process. Experiments were also carried out on a mixture of pharmaceuticals leading to similar conclusions.