Effect of O3 pre-oxidation on AOC

Ozone was selected in studying the variation of AOC in preoxidation process. AOC was increased by 86.9% with the increase of oxidant dosages after coagulation. The AOC was increased by 33.5% only in preoxidation before coagulation. More AOC-NOX, which represents carboxylic acids, was formed and constituted about 40% of AOC during O₃ preoxidation. The AOC/TOC ratio, which indicated assimilation ability of organic carbon, was increased from 8.2% to 16.7% in the preoxidations. The variation of TOC during O₃ preoxidation resulted from the variation of BDOC. The concentration of NBDOC changed little with the increase of oxidant dosages in the preoxidation processes. O₃ preoxidation exhibited better coagulation effect with the dosage less than 1.0 mg·L^-1.