| Algae bloom is the main cause of taste, odor and increased levels of disinfection by-products (DBP) in Winnipeg tap water. Dissolved air flotation (DAF) is effective in removing algae. In this study, a bench-scale continuous DAF unit combined with coagulation and flocculation units was constructed and operated with tap water in Winnipeg at the University of Manitoba. The hydraulic loading rate was 2.2 m/hr, recycling ratio was 8% and saturator pressure was 90 psig (620 kPa). Three different dosages of alum were applied: 41.7 mg/L, 25.5 mg/L and 15.5 mg/L. The coagulation time was 2 minutes and flocculation time was 16 minutes for all three dosages. Besides the regular measurements of turbidity, color, pH commonly conducted in water treatment, the variation of particle size distribution (PSD) in the process was investigated using a microscope and computerized image analysis system. (Abstract shortened by UMI.)... |
