A Comparison of the Performance of the Pre-Ozonation Process and the Use of Coagulants with Ozone in the Removal of Algae from Surface Water

Purifying surface water in moderate-humid climates is challenging due to high levels of organic compounds and diatom algae, which can produce toxic substances. A new method involving chitosan and ferric chloride coagulants, along with pre-ozonation, shows promise for improving water quality. The study examined various conditions, including pH levels and concentrations of chitosan (20–500 mg/L) and ferric chloride (5–100 mg/L), as well as the pH of reaction mixtures (3–11) and ozone concentrations (2–8 mg/L). Optimal results were achieved at a pH of 10 for both coagulants, with 500 mg/L chitosan and 75 mg/L ferric chloride. A pH of 7 for the reaction mixture and an ozone concentration of 8 mg/L were most effective. The pre-ozonation process alone can eliminate 72% of algae, while combining ozone with chitosan and ferric chloride achieved diatom removal rates of 77% and 79%, respectively. These findings highlight the effectiveness of using lower ozone concentrations in conjunction with coagulants for water purification.