Characterization and removal of organic contaminants in ultrapure water systems.

Abstract

Ultrapure water is becoming increasingly important to the semiconductor, pharmaceutical and power industries. Stricter industrial requirements concerning water purity can be realized from pilot scale research. Such a system was designed and operated to determine improved methods to characterize and remove organic contaminants in industrial scale ultrapure water systems. Theoretical modelling of the polishing loop was performed for variable order kinetics; intrinsic reaction parameters were developed, and are potentially scaleable to larger systems. Application of the population balance to the actions of process components on organic particle distributions generated novel oxidation and fragmentation parameters that are scaleable to larger systems. Optimization of bacterial growth media resulted in the increased detection of viable bacterial concentrations. A significant fraction of TOC in the polishing loop was found to exist as assimilable organic carbon; the action of process components, thought to remove contaminants, can generate bacteria nutrients from more complex organics. The situating of a polymeric filter before a UV unit resulted in increased removal of organic contaminants; reversing the sequence enhanced the removal of low molecular weight and low charge to mass ratio compounds. The combination of UV-185 and dissolved ozone resulted in synergistic removal of organic contaminants from ultrapure water. The invention of a novel catalytic filter designed to physically separate and then oxidize contaminants resulted in enhanced removal of organics from ultrapure water. A study of viruses in ultrapure water showed that UV-185 and ozone effectively removed viruses, yet ion exchange gave only two orders of magnitude removal in viable counts. This research may be used to augment present systems and/or design new systems. Continued research along the lines specified in this document will generate further understanding of ultrapure water and ultrapure water systems.