9875580 Harrington The objective of this project is to investigate the influence of water treatment processes that reduce concentrations of disinfectant demanding substances such as natural organic matter on the effectiveness of disinfectants such as ozone and chlorine for inactivation of cryptosporidium species of pathogenic significance in water. The investigator plans on using completely mixed flow-through reactors to evaluate inactivation of cryptosporidium oocysts as a step toward development of mathematical models of the inactivation processes that can be used in engineering design of water treatment processes. The research will be conducted in cooperation with the Wisconsin State Laboratory of Hygiene, which will provide the cryptosporidium species used and will perform determinations of viability. The combined vital dye/flow cytometry approach to be used will permit a larger matrix of experiments than would be possible with other alternatives such as observartions of animal infectivity. The proposal leading to this award was submitted in response to the Faculty Early Career Development (CAREER) Program which emphasizes combining discovery of new knowledge with inspired teaching and enthusiastic learning. the research component of this project is expected to provide knowledge that can be applied in engineering design of processes and systems to inactivate cryptosporidium species from water supplies. The educational component is expected to provide undergraduate and graduate students with access to techniques for study of microbial inactivation processes for water treatment of significance in environmental engineering practice. The investigator's private-sector experience in consulting practice is expected to provide students with practical experiences in relating results of research to utility in engineering practice, in fostering creative thinking and emphasizing communication skills. ***