Comparison on Coagulation Characteristics of Three Inorganic Coagulants for Removing Total Phosphorous from Bioreactor Influent in Sewage Treatment Plant

The selection and dosage location of inorganic coagulants in a sewage treatment plant are very important in removing phosphorus. This study evaluated total phosphorous (T-P) removal by three inorganic coagulants, aluminum sulfate (Alum), poly aluminum chloride (PAC), and polyferric sulfate (PFS). The bioreactor influent in anoxic (tank) condition was used as raw water. Inorganic coagulants were injected at different concentrations of 40 ppm, 60 ppm, 80 ppm, and 100 ppm. At least 80 ppm for Alum, 60 ppm for PAC, and 100 ppm for PFS should be provided to the sewage treatment plant to achieve the T-P removal efficiency of over 70%, the minimum effluent water quality standards in Korea. Also, Alum 8% out of them was estimated to have the lowest operating cost such as 365,368 KRW/day.