UV/sulphite as alternative for UV/H2O2 for micropollutant degradation in drinking water

The UV/SO32– process can be applied to convert organic micropollutants (OMP). The reaction is induced by UV photolysis of sulphite (preferably using a medium pressure (MP) UV lamp). Although in general it is assumed that the UV/SO32− process is an advanced reduction process, our results show degradation of OMP under both anoxic and oxic conditions. Several recalcitrant OMP even show higher degradation rates under oxic conditions than under anoxic conditions. This conversion is affected by the presence of dissolved organic carbon (DOC), HCO3− and NO3−, and thus was more effective in drinking water than in Milli-Q water. The reaction rate constants of the oxic UV/SO32− process in general are lower than those of a UV/H2O2 process, but in cases where the use of H2O2 is not preferred, the UV/SO32− process may be an interesting alternative.