Effect of Ozone Enhanced Flocculation on the Treatment of Secondary Effluent

Due to poor removal efficiency of refractory organic compounds, color and total phosphorous (TP) residual in the secondary effluent by the conventional advanced treatment technology, effect of ozone (O3) enhanced coagulation on the treatment of the secondary effluent was investigated in this research. The results showed that ozone could improve the pollutant removal efficiency. After ozonation, the pollutant removal rate by the coagulation and filtration process increased. O3 pre-treatment could extend the operation cycle of the variable void deep filter. In case of O3 dosage of 1.5 mg/L, PAC dosage of 4 mg/L, flocculation time of 15 min and the filter operation cycle of 16 h, the average removal rate of turbidity, COD, UV254, TP and color by the combination of O3 enhanced microflocculation and variable void deep filtration process (combination technology) was 79.0%, 46.5%, 56.6%, 30.8% and 69.2%, respectively, higher than that by the traditional combination of microflocculation and filtration process (traditional technology). In summary, the combination technology is an effective treatment technology in the tertiary treatment of the secondary effluent.