REACTION ENGINEERING ANALYSIS OFCRYPTOSPORIDIUM PARVUM INACTIVATION IN ALABORATORY-SCALE STATIC MIXER OZONATION SYSTEM

摘要

Performance assessment of full-scale ozonation systems for reduction of pathogens indrinking water relies on engineering analysis and successful scale-up. The objective of this workwas to model inactivation of Cryptosporidium parvum oocysts in a small-scale experimentalozone contactor using reaction engineering principles and to compare model predictions toinactivation measured in challenge experiments. The experimental system was comprised of astatic mixer and short bubble column for rapid ozone dissolution and a reactive flow segment, inthe form of a long pipe, for dissolved ozone contact. Inactivation of C. parvum in theexperimental contactor was measured as infectivity reduction using a CD-1 neonatal mousemodel. Although no inactivation was measured within the static mixer itself, this studydemonstrated that efficient C. parvum inactivation can be achieved in when a static mixer isintegrated into a continuous-flow contacting system. Furthermore, inactivation was adequatelypredicted using a simple model based on a published non-linear kinetic model of C. parvumoocyst inactivation by ozone and assuming ideal plug flow. Segregrated flow analysis and theexperimental results showed that the laminar macro-mixing pattern in the pipe did notsignificantly reduce the efficiency of inactivation. A CFSTR-in-series model did not adequatelydescribe the macro-mixing pattern and under-estimated inactivation.