Coliform and virus removal by filtration processes. Figure 7 compares the efficiencies of the three filtration methods for the removal of total coliform faecal coliform and CoxB3 virus from the secondary effluent. There were no data available regarding removal by O3-BAC process due to difficulty of virus seeding to the raw wa biological treatment. It can be seen from Figure 7 that O3-BAC and coagulation-fil nater f are not so effective in coliforms removal(approximately only 2 to 3-log decrease), while UF shows an excellent effect of almost complete removal of both total coliform and faecal coliform. However, regarding the seeded CoxB3 virus, UF shows almost no advantage over coagulation-filtration. The UF membrane used in this study has a molecular cut off of 30,000 Daltons. Its pore size should be much smaller than the size 因CoXB3國T.Co口F.col oQO=E6=6O 9 O3-BAC Coagulated treated Figure 7 Comparison of three filtration processes for coliforms and virus removal CoxB3图Tco口Fco a5-6Eo 922 8 Chlorine dose/mg/L o5-6E6= Figure 8 Comparison of chlorination and ozonation for coliforms and virus removalColiform and virus removal/inactivation Coliform and virus removal by filtration processes. Figure 7 compares the efficiencies of the three filtration methods for the removal of total coliform, faecal coliform and CoxB3 virus from the secondary effluent. There were no data available regarding CoxB3 removal by O3-BAC process due to difficulty of virus seeding to the raw water for biological treatment. It can be seen from Figure 7 that O3-BAC and coagulation-filtration are not so effective in coliforms removal (approximately only 2 to 3-log decrease), while UF shows an excellent effect of almost complete removal of both total coliform and faecal coliform. However, regarding the seeded CoxB3 virus, UF shows almost no advantage over coagulation-filtration. The UF membrane used in this study has a molecular cut off of 30,000 Daltons. Its pore size should be much smaller than the size 0 2 4 6 8 Coliform or TCID50/log CoxB3 T. Coli F. Coli No data available ND ND Raw water O3-BAC treated Coagulated UF treated Figure 7 Comparison of three filtration processes for coliforms and virus removal 0 2 4 6 8 0 0.11 0.52 1.05 2.1 Ozone dose/mg/L Coliform or TCID50/log ND ND ND 0 2 4 6 8 0 3 4.5 6 8 Chlorine dose/mg/L Coliform or TCID50/log CoxB3 T.Coli F.Coli NDNDND ND ND ND Figure 8 Comparison of chlorination and ozonation for coliforms and virus removal X.C. Wang et al. 218