57) With reference to Table 4, list the chemical disinfectants in order of most effective to least effective. Include in the list the Ct values for each chemical for 90 percent (1.0 log) inactivation of Giardia lamblia cysts at 10C and pH 7.

20C [(mg/l). min) 0.5 TABLE 4 ct Values for 0.5-log and 1.0-log Inactivation of Giardia lamblia Cysts Water Temperature Log 0.5C 5C 10C 15C PH Inactivation [(mg/l) - min] [(mg/l). min) [(mg/l). min) [(mg/l). min) Free chlorine 25 18 13 9 1.0 49 35 26 18 0.5 35 25 19 13 1.0 70 50 37 25 0.5 51 36 27 18 1.0 101 72 54 36 Preformed chloramine 6-9 0.5 640 370 310 250 6-9 1.0 1300 740 620 500 Chloride dioxide 6-9 0.5 10 4.3 4.0 3.2 6-9 1.0 21 8.7 7.7 6.3 Ozone 6-9 0.5 0.48 0.32 0.23 0.16 6-9 1.0 0.97 0.63 0.48 0.32 667788 ORORO o in bin bin 7 13 9 18 14 27 in 190 370 2.5 5.0 0.12 0.24 "Free chlorine values are based on a residual of 1.0 mgl. Source: Adapted from Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems Using Surface Water Sources. U.S. Environment Protection Agency