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

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/S(2)O(8)(2- )limit the interest in the process. Experiments were also carried out on a mixture of pharmaceuticals leading to similar conclusions.

Automated summary

This study compares UVA and UVC radiation for the removal of micropollutants in treated wastewater through the activation of H2O2 or S2O82-. The results indicate that UVC radiation leads to faster degradation rates, and S2O82- is photolyzed faster than H2O2. In treated wastewater, the presence of organic matter inhibits the degradation of estrogen, with stronger inhibitions observed in S2O82- processes.