Promoting Hydroxyl Radical Production during Ozonation of Municipal Wastewater

Hydroxyl radical (HO center dot) production during ozonation of municipal wastewater was investigated with and without liquid or solid-phase promoters. For liquid-phase promoters, an ozone dose threshold was observed, below which addition of H2O2 yielded no discernible increase in the rate of HO center dot production. This threshold occurs because ozonation of bulk organics in wastewater promotes HO center dot due to the presence of ambient promoters. Although solid-phase catalysts are reported to promote oxidation of contaminants, ozonation of effluent over TiO2 or GAC was no more effective on trace organic removal than over inert surfaces.