Comparing potassium permanganate, chlorine dioxide, and chlorine oxidation for manganese control of a volcanic island surface water treated with a conventional coagulation, sedimentation, and filtration process

Abstract

AbstractA comparison of the effectiveness of potassium permanganate (KMnO4), chlorine dioxide (ClO2), and chlorine (Cl2) oxidation pretreatment for manganese (Mn) control from a surface water reservoir on the volcanic island of Guam has been completed. Source water dissolved Mn content was determined to be 7.34 μg/L at a reservoir intake depth of 10 ft, 9.85 μg/L at a depth of 20 ft, 41.6 μg/L at a depth of 30 ft, and 775 μg/L at a 40 foot depth. For the intake depth of 10 ft, it was found that a ClO2 dose of 1.1 mg/L reduced Mn by an average of 98.7%, as compared to an average of 95.9% using a KMnO4 dosage of 1.75 mg/L. Cl2 was found not to reduce dissolved Mn to any extent at dosages of 1.25 mg/L. It was determined that pink water formation occurred with less than 0.5 mg/L of a permanganate overdose. Additionally, a 1.1 mg/L ClO2 dose produced an average chlorite and chlorate by-product concentration of 780–1,080 μg/L, respectively. Results demonstrated that ClO2 would be the preferred oxidant for Mn co...