Experience of ozone-biological aerated filter process in advanced wastewater treatment

An ozone-biological aerated filter process was operated for more than one year to evaluate its feasibility in polishing the secondary effluent of domestic wastewater treatment. The average effluent COD, UV254, color, turbidity, NH3-N were 33.8 mg/L, 0.148 cm^-1, 12.6, 1.3 NTU and 6.4 mg/L with the corresponding removal rates 51.9%, 26.6%, 77.2%, 76.4%, 78.0% respectively. Main operational parameters were: ozone dosage 16 mg/L, ozone reaction time 15 min, hydraulic retention time of the biological aerated filter 1 h, ratio of air to water 3:1. The filtration bed of the biological aerated filter was filled with 1 m high 1~1.2 mm quartz sand. All results showed excellent performance of the ozone-biological aerated filter process. Experiences proved that the operation parameters such as dosage of ozone should be changed with the influent quality to acquire the best quality of the effluent.