Background and objectives: The performance of ozone in water disinfection depends on process factors as well as the design parameters of the ozone unit that improper design of ozonation unit and an imbalance between ozone doses with the quality of the water used is causing changes in water quality. The overall goal of this study is to investigate the effect of ozonation process factors on drinking water quality parameters.
 
Methods: This study is on a pilot scale in four different scenarios to evaluate the effectiveness of ozonation process factors on the simulated water quality parameters (turbidity, color, chlorophyll a, pH and TOC) was performed. In all scenarios, ozone doses between 1 and 5 grams per hour are considered. Contact time (minutes), temperature (degrees Celsius) and pH are equal in scenarios 1 to 4, respectively; 5, 23.9 and 5.6-4 (Scenario 1), 10, 23.8 and 6.8-5.6 (Scenario 2), 15, 23.8 and 6.8 (Scenario 3) and 20, 23.6 and 8.6 (Scenario 4).
Results: The results of data in different scenarios showed that, injectable ozone dose, ozone contact time with water, pH and temperature it has the greatest effect on ozonation performance. The average removal rate of turbidity, TOC, color  and chlorophyll a parameters in scenarios 1 to 3 is equal to; (Scenario 1; 12.85, 1.05, 5.3 and 41.8%), (Scenario 2; 14.35, 12.3, 12.75 and 60), (Scenario 3; 31.65, 16.3, 18 and 67.3) . Studies showed that in scenario 4 with an alkaline pH (10.6) and an average temperature of 23.6 ° C with an injection ozone dose of 5 grams per hour and a contact time of 20 minutes, the removal rate of quality parameters of water samples including; Turbidity, TOC, color and chlorophyll a was higher than other scenarios and are equal to: 44.07%, 32.6%, 39.8% and 92.7%, respectively.
Conclusion: The results showed that among the process factors governing ozonation, temperature and pH have the greatest effect on water ozonation, So that with the decrease of temperature and increase of pH, the removal rate of parameters increases. The contact time and the dose of injected ozone have a direct effect on the removal of parameters, So that the effect of these two parameters depends on the hydraulic conditions of the ozonation tank and the quality of raw water. Reviews various scenarios showed that in the optimal ozonation conditions, the highest removal rate of parameters is related to chlorophyll a, turbidity, color and TOC, respectively.