UV-H2O2 based AOP and its integration with biological activated carbon treatment for DBP reduction in drinking water

The presence of disinfection byproducts (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs) in drinking water is of great concern due to their adverse effects on human health. Emerging regulation limiting the concentration of DBPs in drinking water has increased demands for technologies and processes which reduce the formation of DBPs in drinking water. In this study, UV-H₂O₂ based advance oxidation process (AOP) was used to treat raw surface water. Experiments were conducted using low pressure mercury vapor UV lamps in collimated beam and flow-through annular photoreactors. The effect of UV fluence (0–3500 mJ cm⁻²) and hydrogen peroxide concentration (0–23 mg l⁻¹) in reducing the concentration of THMs and HAAs was examined. The UV-H₂O₂ AOP was then coupled with a downstream biological activated carbon (BAC) treatment to assess the synergetic benefits of combining the two treatments. It was observed that UV-H₂O₂ AOP was only effective at reducing DBPs at UV fluences of more than 1000 mJ cm⁻²and initial H₂O₂ concentrations of about or greater than 23 mg l⁻¹. However, the combined AOP–BAC treatment showed significant reductions of 43%, 52%, and 59% relative to untreated raw water for DBPs, TOC, and UV₂₅₄, respectively.