Synchronous pre-oxidation-coagulation for the efficient treatment of organic compounds by UV/sodium percarbonate

The essential step to improve the coagulation efficiency is to select and optimize the pre-oxidation process. Ultraviolet/sodium percarbonate (UV/SPC) can be employed as an alternative system to UV/H₂O₂ in drinking water treatment plant operation, benefiting from the solid stability properties with the equivalent effect. At present, the studies on UV/SPC, and other UV/advanced oxidation processes (UV/H₂O₂, UV/persulfate, UV/chlorine, etc.), mostly focus on the advanced water treatment after filtration. This study notes that UV/SPC has advantages in the pre-oxidized organics. UV/SPC improving the effect of coagulation on dissolved organic carbon (DOC) elimination by up to 25 %, the optimal UV dose and SPC dosage are 600 mJ/cm² and 20 mg/L verified by a pilot experiment; the decomposition degree and conversion of organics which is most conducive to follow-up coagulation treatment is obtained through the detailed comparison of the influence range of UV dose or the C_SPC on the molecule structure of organics; the disparate role of UV was unraveled in UV photolysis pre-oxidation and UV/SPC pre-oxidation and coagulation, including the influence regularity of UV transmittance (UVT) and processing flow rate on UV dose; confirm that UV/SPC alleviates the risk of the generation of disinfection by-products (DBPs) to 51.15 %. This study corroborates the potential of UV/SPC as a pre-oxidation technology at the application level.