Photocatalytic oxidation, GAC and biotreatment combinations: an alternative to the coagulation of hydrophilic rich waters?

This study investigated the photocatalytic oxidation of a raw water rich in hydrophilic natural organic matter ( NOM) and the impact on the removal of: dissolved organic carbon (DOC), UV absorbance at 254 nm ( UV 254) and trihalomethanes formation potential ( THMFP). Dissolved organic carbon and UV 254 removals were 40% and 55%, respectively, after 1 min irradiation time and 1 g L-1 dose of TiO2. The THMFP content was reduced from 305 mu g L-1 in raw water to 144 mu g L-1 after 10 min treatment, whereas chlorine reactivity was stable with treatment. The results showed that larger molecular weight species were preferentially degraded during the process. Dissolved organic carbon and THMFP removals reached 60% and 70%, respectively, after photocatalytic oxidation and granular activated carbon ( GAC) columns.