Removal of Dimethylamine by Ozone Combined with Hydrogen Peroxide (O3/H2O2)

Ozonation of dimethylamine (DMA), the most direct and common precursor of high carcinogenic disinfection by-product N-nitrosodimethylamine (NDMA), in aqueous solutions and in the presence of H₂O₂ was studied at ozone doses of 1.8 mg/L. The removal ratio of DMA increases from 46.7% to 77.1% with the dosage of H₂O₂ increasing from 0 to 1 mM, and the removal rate can be improved by increasing pH. According to the results of H₂O₂ addition time experiments, hydroxyl radicals might play important roles in the destruction of DMA during combined oxidation process. With the treatment of O₃/H₂O₂ for 24 h (containing 0.5 mM DMA), the yield of NDMA formation was below our detection limit (0.1¿g/L) and the yield of NDMA formation after chloramination (24 h) of DMA containing water could be reduced by 90%.