Background: Ozone can be used as a single technology or in combination with other processes to improve the coagulation- flocculation or biodegradability in order to remove pollutants in natural water treatment. Methods: In this study, the effects of pre-ozonation with coagulant substances on the quality parameters of drinking water were investigated using humic acid, kaolin, clay, and green algae in a pilot scale. This study was conducted under laboratory conditions (at both acidic and alkaline pH in different dosages of ozone and coagulant at ozone contact time with simulated water sample (5-20 minutes) in different scenarios). Results: The highest removal efficiency of parameters in the state of pre-ozonation alone and preozonation with a coagulant was observed at contact time of 20 minutes, ozone dosage of 5 g/h, coagulant dosage of 25 mg/L, at alkaline pH along with a decrease in temperature. So that, the average removal rate of turbidity, total organic carbon (TOC), color, and chlorophyll a in contact time of 20 minutes was 76.9%, 52.8%, 66.6%, and 85%, respectively. However, compared to ozonation under similar conditions, the reduction in turbidity, TOC, color, and chlorophyll a was 36.13%, 24.4%, 32.13%, and 79.6%, respectively. Also, it was revealed that pre-ozonation with coagulant could effectively improve the removal of parameters. Conclusion: However, since pre-ozonation can be effectively used to improve the coagulation efficacy in the drinking water treatment, the pre-ozonation combined with coagulation is proposed as an alternative to conventional coagulation to improve the process of drinking water treatment plant.

The study investigated the effects of pre-ozonation on the parameters such as turbidity, color, chlorophyll a and TOC on a pilot scale. The investigation results indicate that the amount of required ozone to remove TOC, color and turbidity depends on the quality of inlet water, and the efficiency of water ozonation depends on the process factors such as ozone dose, temperature, pH and ozone-water contact time. The study likewise shows that the lower amount of turbidity, TOC, temperature and higher alkaline pH of sample water boost the ozonation effect on removing the variables in question. The results also demonstrate a direct relationship between pH, ozone dosage and contact time, as well as an indirect relationship between temprerature and the removal of parameters.

Background and objectives:Pre-ozonation in water treatment is used for various purposes such as; improving the coagulation process, reducing the production of trihalomethanes, color removal, removal of iron and manganese, control of microorganisms, and removal of organic matter. The main objective of this paper is to investigate the effects of pre-ozonation on the physical, chemical, and biological properties of drinking water.Methods:This study on a real scale was conducted on the pre-ozonation unit of the Koohsabz drinking water treatment plant for 6 months. In this study, sampling of raw water entering the pre-ozonation unit and ozonized water was done randomly with glass sampling containers. 4 samples per month and a total of 24 samples were taken to evaluate the trends of changes in the parameters. The necessary tests according to the method presented in the standard method book (twentieth edition) on the samples have been done to investigate the effects of pre-ozonation on the physicochemical and biological parameters. Results :The studies showed that the turbidity and TOC (Total Organic Carbon) removal efficiency in the pre-ozonation process of the Koohsabz drinking water treatment plant was about 62% and 18. 83%, respectively, and it has no effect on pH. Also, the removal rate of Fe and Mn in the pre-ozonation process was 91.5 and 82%, respectively. Evaluate the effectiveness of pre-ozonation in watercolor removal showed that, by increasing the dosage and the concentration of ozone injection, significant changes did not occur on further reduction of color and color precursors and the removal rate of color precursor compounds, such as the chlorophyll a, is about 21%. Conclusion:The results indicated that ozone could not change any physical parameters such as pH and color, but it has a significant effect on the chemical properties and reduced biological parameters by about 21%.

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