IRON AND MANGANESE REMOVAL WITH OZONE.

An extensive pilot study was conducted in the Moscow, Idaho municipal water system. The study demonstrated that ozone effectively oxidized the iron and manganese to an insoluble form which could be filtered from the water. The manganese was more difficult to oxidize than the iron. Treating the raw water (iron and manganese concentration of 9. 5 and 1. 2 mg/l, respectively) with an ozone dosage rate of 8. 8 mg/l removed all the iron and manganese to below Public Health Drinking Water Standards. Reducing the dosge to 6. 3 mg/l still removed the iron but a 0. 1 mg/l manganese residual remained. Complete oxidation of the mineral required a reaction time of 30 seconds. Filtration studies indicated that a relatively fine medium is required to remove the oxide precipitation. Cost comparisons with other treatment systems showed that the ozone process was an economically attractive treatment.