Mechanisms for synergistic oxidation of organics in ultrapure water systems

A mechanistic model is developed for the distribution, oxidation, and removal of organic impurities in typical polishing loops of ultrapure water (UPW) plants. The model is applied to the case of the oxidation of organics by ultraviolet (UV), ozone, and a unique method of adding ozone to the UV unit. The model is validated with direct experimental measurements using various oxidation tests. In particular, the accumulation problem related to the recalcitrant (hard to remove) impurities in the UPW systems with recycle is explained. The model is also used to analyze the dynamic behavior of polishing and reclaim/recycle loops. The results show the potential oscillatory behavior of UPW loops in case of impurity surges. This behavior is important and needs to be prevented to avoid metrology and control problems.