Purification of polluted river water by ultrafiltration-ozonization-biological activated carbon filtration

The main Nakdong river water mixed with polluted Kumho river was used as raw water in this research. The removal efficiencies of TOC and UV₂₅₄ nm absorbance in the ultrafiltration process were both approximately 15% higher than those in the coagulation/rapid sand filtration process. In the biological activated carbon filter, the ammonia nitrogen removal efficiency goes up to over 90% after 35 days of operation in the early spring at empty bed contact time (EBCT) of 25 min. At EBCT of 25 min, the removal of TOC and UV₂₅₄ nm absorbance were higher by about 5% and 10%, respectively, than at EBCT of 10 min. By the combination of ozonization to ultrafiltration-biological activated carbon process, the AOX and THM formation potential were effectively reduced.