| The research presented in this thesis examined the passage of C. parvum and potential surrogates for C. parvum through granular media filters during periods of optimal and non-optimal filter operation. A thorough review of the relevant filtration and C. parvum literature emphasized the difficulty in accurately enumerating C. parvum from water samples. A relatively simple analytical method for concentrating and enumerating C. parvum during filtration studies was implemented and optimized. Then, to address the uncertainty or reliability of C. parvum concentration and removal data, a new quantitative tool that incorporated several sources of error (representative sampling, random analytical error, and non-constant analytical recovery) was developed. The statistical model assumed a Poisson distribution for the true sample counts, a binomial distribution for modeling the recovered fraction of oocysts, and a Beta distribution for describing the uncertainty of oocyst recovery. A numerical technique (Gibbs sampler) was then applied to the statistical model to determine confidence intervals for C. parvum concentration and removal data. This method of describing the uncertainty associated with C. parvum data (confidence intervals calculated via the Gibbs sampler) was used throughout this thesis research because it allowed for comparison between different data sets with, in some cases, different analytical recoveries.; Bench-scale experiments were performed to determine if viable and chemically-inactivated C. parvum oocysts were similarly removed by granular media filters at a variety of operating conditions. These experiments were critical because of the potential health risks associated with the experimental use and release of viable oocysts.; Pilot-scale experiments represented the majority of the experimental efforts and focused on investigating design and operational strategies for maximizing C. parvum removal by filtration. Multiple research platforms permitted investigation of different types of raw waters, water temperatures, coagulation regimes, and filter designs. Formalin-inactivated C. parvum oocysts were seeded at all of the experimental locations. In addition to turbidity and particle concentration evaluations, polystyrene microspheres were evaluated as potential surrogates for C. parvum because they were similar to oocysts in size and easy to identify and enumerate.; The pilot-scale investigations resulted in several operational and design implications and strategies for maximizing C. parvum removal by granular media filtration, the most notable of which were the importance of optimized chemical pretreatment (coagulation prior to filtration) and the potential for increased pathogen passage during end-of-run operation. (Abstract shortened by UMI.)... |
