15.0 10.0 5.0 Treated water: Average 5.3 mg/L 0.0 U天与 502 Raw water. Average 0.219 cm reated water: Average 0.097 cm 强强 Date of sampling(in 2004) Figure 5 TOC and UV254 removal by DOF separator both the low aromaticity of the raw water and the low ozone dose, 1. 6 mg/L, which may not be enough to decompose organic matter. The organic removal was mainly achieved by coagulation and flotation. Bacteria and coliform inactivation. Figure 6 shows the total bacteria and total coliform counts in the treated water. The dof achieved a 3-log removal of total bacteria and 2.3- log removal of total coliform in comparison with the bacteria counts shown in Table 1 Due to the limitation of ozone supply capacity of the experimental system, investigation could not be conducted for bacteria and coliform removal at an ozone dose higher than 1.6 mg/L. However, the DOF separator showed its advantage in fulfilling simultaneous disinfection and removal of other pollutants, even at an insufficient ozone dose of 1. 6 mg/L Effect of ozone dose. In the DOF separation process, ozone-rich air is the air source for flotation and ozone also plays the function of oxidation. Figure 7 shows the influence of 口 Total bacteria (mL Total colifom《100mL) Sample number Figure 6 Inactivation of microorganisms by dOF separatorboth the low aromaticity of the raw water and the low ozone dose, 1.6 mg/L, which may not be enough to decompose organic matter. The organic removal was mainly achieved by coagulation and flotation. Bacteria and coliform inactivation. Figure 6 shows the total bacteria and total coliform counts in the treated water. The DOF achieved a 3-log removal of total bacteria and 2.3- log removal of total coliform in comparison with the bacteria counts shown in Table 1. Due to the limitation of ozone supply capacity of the experimental system, investigation could not be conducted for bacteria and coliform removal at an ozone dose higher than 1.6 mg/L. However, the DOF separator showed its advantage in fulfilling simultaneous disinfection and removal of other pollutants, even at an insufficient ozone dose of 1.6 mg/L. Evaluation of the DOF separation process Effect of ozone dose. In the DOF separation process, ozone-rich air is the air source for flotation and ozone also plays the function of oxidation. Figure 7 shows the influence of 0.0 5.0 10.0 15.0 TOC (mg/L) Raw water: Average 11.3 mg/L Treated water: Average 5.3 mg/L 0.0 0.1 0.2 0.3 5-Oct 10-Oct 15-Oct 20-Oct 25-Oct 30-Oct 4-Nov 9-Nov 14-Nov 19-Nov 24-Nov 29-Nov 4-Dec 9-Dec 14-Dec 19-Dec 24-Dec Date of sampling (in 2004) UV254 (cm–1) Raw water: Average 0.219 cm–1 Treated water: Average 0.097 cm–1 Figure 5 TOC and UV254 removal by DOF separator 0 10 20 30 40 50 12 34 Sample number cfu Total bacteria (/mL) Total coliform (/100mL) Figure 6 Inactivation of microorganisms by DOF separator P.K. Jin et al. 155