The object of this was to investigation the effect of continuous mechanical mixing on the disinfection of settled domestic of settled domestic sewage with iodine. The variable investigated was the power input to the system which was a function of mixing intensity. Five experiments were run usfrtt a six-bladed turbine agitator in a fully baffled tank. The mixing intestines of the first three experiments were 0.292, 0.00748, and 0.0641 foot pounds per second per 1,000 gallons, respectively. The mixing was contInuous throughout the experiment. The last two experiments employed a mixing intensity of 0.000876 foot pounds per second per 1,000 gallons. Most Probably Number determinations of Escherichia coli were made at time intervals of 0, 0.5, 1.5, 2, 3, 4, 6, 8, and 10 minutes respectively, for each experiment. All ten minute Iodine residuals were in the range of 1.70 to 1.80 parts per million. Alt experiments were conducted at 20 degrees centigrade. Similar rates of disinfection were obtained at mixing intestines of 0.292, 0.0641, and 0.00748 foot pounds per second per 1,000 gallons. The disinfection rate at 0.000876 foot pounds per 1,000 gallons was inferior to that of the previously mentioned rates. The following conclusions were made after comparing these results with a previous investigation. 1. Similar continuous mixing disinfection occurred in the range of power to volume ratio of 0.00748 to 148 foot pounds per second per 1,000 gallons. 2. Inferior continuous mixing disinfection·occurred at the power to volume ratio of 0.000876 foot pound per second per 1,000 gallons and under the condition of no mixing. 3. A system operating at the power to volume ratio of 0.00748 foot pounds per second per 1,000 gallons for one minute·appears to provide for complete blending of iodine with the sewage under the conditions of the present Investigation. The suggested power requirement is equivalent to 9.46 x 10⁻⁶ horsepower per million gallons per day. / Master of Science