An investigation of Cryptosporidium parvum and silica surface forces in relation to water treatment

Cryptosporidium oocysts have worldwide distribution in water supplies, and frequent outbreaks of cyrptosporidiosis over the last few decades have prompted authorities to explore solutions for improving their removal during water treatment. The research presented in this thesis examined at a fundamental level the charge characteristics and the forces of interaction between silica, used to model the media used in sand bed filtration, and C. parvum oocysts under various environmental conditions (addition of polyelectrolyte (PE) with varying charge densities (CDs); dosing schedule of polyelectrolyte addition).; Microelectrophoretic studies were performed to determine the charge characteristics for silica and C. parvum oocysts. The iso-electric points (IEPs) were determined for each, as a function of PE concentration, indicating optimum PE dosages. These experiments indicated the optimum concentration of PE to conduct AFM studies to. The gradual addition of PE neutralized the negatively charged silica and C. parvum oocysts and eventually completely reversed the charge. (Abstract shortened by UMI.)...