Evaluation of Escherichia coli O157:H7 and Salmonella enterica inactivation in water by several treatment technologies

Water treatment technologies are necessary for microbial pathogen removal from potable water. Human activities, including large industries in agriculture and manufacturing, produce massive amounts of waste that invariably end up in water supplies. There will always be a need for water treatment technologies that evolve and progress as waste volume and complexity increases. Further exploration and development of current treatment methods will be necessary to match this demand. In this study, wintergreen essential oil, physical filtration, iodine and chlorine dioxide tablets, sunlight, artificial UV light, and TiO2 photocatalyst treatment methods and their effects on waterborne pathogens Escherichia coli O157:H7 and Salmonella enterica are evaluated. The effect of wintergreen essential oil derived from Gaultheria procumbens was analyzed against E. coli and S. enterica in concentrations of 5 μL/1.5 mL, 2.5 μL/1.5 mL, and 1 μL/1.5 mL (wintergreen/sterilized deionized water). Experiments of UV lamp exposure, with and without immobilized TiO2 photocatalyst, were performed to determine pathogen inactivation efficiency. Sunlight alone and with immobilized TiO2 photocatalyst were studied for pathogen inactivation potential as well. Lastly, physical filtration via portable backpacking pump filter and purification by emergency chlorine dioxide and iodine tablets were tested for removal and purification efficiencies against E. coli and S. enterica. Bacterial viability was quantified by serial dilution and viable plate counting. Preliminary experiments were also done to develop methods and procedures, including the effect of refrigerated storage on E. coli viability in Tryptic Soy Broth and the development of E. coli and S. enterica growth curves by optical density at 600 nm (OD 600 ) with spectrophotometry measurements. Results of these experiments are discussed and compared. Statistical analysis via one-way ANOVA with a post-hoc Tukey HSD was used to analyze difference in treatments for significance. Results showed pathogen removal for all technologies studied, to varying degrees. Some examples include: 5-log reduction was achieved in E. coli with sunlight-only at 6 hours; 3-log reduction was achieved in S. enterica with sunlight-only at 7.5 hours, E. coli UV lamp-only at 8 hours, E. coli and S. enterica with sunlight/TiO2 at 6 and 7.5 hours, respectively, and E. coli with a 5 μL concentration of Wintergreen essential oil at 50 minutes; 3-log reduction in E. coli was observed when the 5 μL concentration of wintergreen essential oil was applied for 50 minutes, 2-log reduction in E. coli was observed after 50 minutes of 2.5 μL concentration treatment, while the 1 μL concentration of wintergreen essential oil achieved only a 40% reduction in E. coli at 50 minutes. The results from this research may influence further pursuit in one or combinations of these water treatment technologies.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Agricultural & Biological Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Miller, Matthew Robert

Contributors dc:contributor

• Davidson, Paul C
• Kalita, Prasanta K
• Bhattarai, Rabin

• Escherichia coli O157:H7
• Salmonella enterica

Statement dc:rights

• Copyright 2021 Matthew Miller

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/113353

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/113353