## 3 Results and Discussion
### Effects of O3 on S. typhimurium Inactivation
Specifically, in medium, hard wheat, _Tritcium aestivum_ L., ozone gas levels at 5 mg/L at 3.3 L/min in time intervals of 0, 0.5, 1.0, 1.5, and 2.0 h were influential in the degradation of the wheat endosperm starch granule but not against the protein or fat contents in the wheat (\(p<0.05\)) [72]. In foods, ozone treatments of 0.35 ppm for 3 days at 2 \({}^{\circ}\)C were partially effective in preventing fungal growth in strawberries [73] and reduced _E. coli_ and _Listeria_ spp. in spinach when it came in contact with ozone exposure of 1 ppm for 10 min and 10 ppm for 20 min [64]. Other studies have shown that ozone treatments were efficacious against multiple pathogenic bacterial strains such as _Escherichia coli_, _Staphylococcus aureus_, _Enterococcus faecalis_, _Klebisella pneumoniae_, _Acinetobacter baumannii_, and _Pseudomonas aeruginosa_. The concentrations of the O\({}_{3}\) treatments were split into separate groups: an ozone-oxygen mixture group containing 20 \(\upmu\)g of O\({}_{3}\)/mL for 5 min, 100% oxygen group for 5 min, and a baseline group where no gas was used. As a result, the ozone-oxygen mixture stopped all the bacterial strains present [74]. Ozone treatments have also been proved to reduce antibiotic resistance genes and pathogenic bacteria in wastewater [73; 74; 75; 76; 77]. Using 1 g of ozone/g, the ozonation reduced the micro-pollutants like antibiotic drugs or biocides and effectively removed approximately 2 log units of the micro-pollutants [40]. Previous studies have tested the effectiveness of a domestic ozone generator in reducing bacterial and fungal species of _E coli_, _Proteus_ sp., _Pseudomonas aeruginosa_, _Serratia_ sp., three strains of _Staphylococcus aureus_, _Candida albicans_, and _Aspergillus fumigatus_ using ozone concentrations of 0.3 to 0.9 ppm for 4 h. In these conditions, there was a bactericidal effect in all of the species except _Candida albicans_ which showed more resistance. In other experiments that dealt with 0.9 ppm ozone exposure for 0-4 h, bacteria was most rapidly reduced in _S. aureus_ within the first few hours until the bactericidal effect rate was slowed significantly. At 1 ppm, ozone effectively reduced the bacterial numbers of most of the tested species by 95% [78]. Pathogen reduction by ozone treatment is likely to be affected by the type of material to be treated, its physical properties, and the mode of application. In a previous study [53], we designed an ozone chamber to expose solid poultry litter to ozone gas. Because liquid dairy manure has a higher amount of moisture, the current research needed substantial modification in previous experiments for diffusing ozone uniformly inside the liquid manure. In contrast to the liquid dairy manure treatment experiment presented here, diffusion of ozone inside of poultry litter was not needed because poultry litter moisture content was considerably low, and poultry litter was in the form of solid pellets. Published results showed that pathogen reduction was reduced when moisture level was increased [53], which indicates that the ozone impacts on pathogen removal may vary from one material to another depending on moisture level and type of material (liquid vs. solid surface). In addition to bacteria removal, ozone treatments are also proven suitable for virus removal. For example, several human pathogenic viruses in sewage were reduced to undetectable levels, when sewage was exposed to ozone treatment suggesting that ozone can be a promising technique for reducing the transmission of human viruses [21].