Investigation of Effective Parameters in the Combined System of Microstrainer and Ozonation in the Removal of Algae from Raw Water

The presence of algae in the water treatment process is problematic. The best way to control algae is to remove the algae cell intact without rupturing the cell, as most common methods cause disinfection by-products, which are often very dangerous. The aim of this study was to evaluate the efficiency of microstrainer and ozonation systems in combined removal of algae from raw water. For this purpose, Box-Behnken Design was used in the Response Surface Methodology by Design Expert software. Experimental variables included input turbidity (50-150 NTU), microstrainer surface load (10.8-18 m/h) and injectable ozone dose (1-3 mg/L). Based on the experimental conditions, the algae removal efficiency in the integrated microstrainer and ozonation system was 39.64-88.76%. The parameters of inlet water turbidity, injected ozone dose and micro-strainer surface load with effect coefficients of 15.37, 8.98 and 4.01, respectively, had the greatest effect on system efficiency in algae removal. Increasing the turbidity and surface load of the microstrainer decreased the algal removal efficiency and increased the injection ozone dose increased the efficiency. The final model based on the desired parameters was obtained as a quadratic equation with correlation coefficient, modified correlation coefficient and predicted correlation coefficient equal to 0.948, 0.928 and 0.868, respectively.