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

A 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 control as compared to KMnO₄ or Cl₂ for the volcanic water supply evaluated in this study. The research also verified that a 0.10-micron filter produced more accurate dissolved Mn results than the standard method use of 0.45-micron filter in laboratory procedures.

Keywords:

• Oxidation
• Manganese
• Chlorine
• Chlorine dioxide
• Potassium permanganate
• Surface water

Acknowledgments

The work was supported by Naval Facilities Engineering Command (NAVFAC) A-E Contract N62742-11-D-0101 (Pearl Harbor, HI) as administered by Brown and Caldwell (Honolulu, HI) through UCF Funding Agreement 16208121. The authors would also like to express their gratitude to the DZSP21 laboratory staff in Santa Rita, Guam. Without their help the project would have not been possible. The authors would also like to express gratitude to Brown and Caldwell, specifically Doug Lee, Bill Persich and Lynn Williams for their guidance throughout the course of this research. Also, the significant assistance of Maria Lewis of NAVFAC, Guam, Marianas Islands, in this research was greatly appreciated.