Advanced sewage treatment with ozone under excess sludge reduction, disinfection and removal of EDCs

A new advanced treatment system, which consists of biological nutrient removal process combined with reduction of excess sludge by ozonation and phosphorus recovery by crystallization and polishing-up ozonation process, was developed based on the fundamental studies and demonstrated by the demonstration plant set in AICHI EXPO 2005. Reduction of withdrawn excess sludge by 90% and phosphorus recovery by 70% were accomplished without any adverse effects on biological nutrient removal. The concentrations of SS, BOD, T-P and T-N in the effluent were less than 1.0, 3.0, 0.5 and 10 mg/L, respectively. EDCs were reduced to almost undetectable level and 2-log disinfection of Bacillus subtilis was established. The energy amount required for the operation was saved by 40% when compared with a conventional system to get the same level of water quality.