Potassium permanganate has a long history of successfully treating drinking water. It is widely used by facilities to help remove impurities, such as iron and manganese in water, to help adhere to regulatory guidelines.

Queensboro Water Treatment Plant in Bear Mountain, New York has an average flow of 150,000 GPD. In the summer of 2000, the plant personnel replaced chlorine with permanganate as a pre-oxidant to control taste and odor, color, turbidity, iron, and manganese in their drinking water. CARUSOL ® Liquid Permanganate was chosen over the granular potassium permanganate, since it could be easily stored and handled. The feed equipment was simplified and the manpower needed would be minimized.

• Effectively replaces chlorine as a pre-oxidant
• Significantly reduces true color, turbidity levels, iron, and manganese in water
• Improves taste and odor
• Enhances floc settling, aids in coagulation, and reduces polymer usage
• Controls THM and HAA formation at the beginning of the treatment process

Carus Corporation would like to acknowledge the efforts of Paul Christian of the Queensboro Water Treatment Plant, Bear Mountain, New York.

Permanganate is used in the removal of iron (Fe) and manganese (Mn) in surface water and ground water systems with filtration. Permanganate oxidizes soluble iron and manganese to insoluble precipitates. The precipitates are removed from the water supply in the clarification and filtration processes.

Factors that affect removal efficiency include water chemistry, pH, temperature, and application point. Reaction times are rapid under normal conditions of temperature and pH. Generally, temperatures <35°F, and pH values <5.5 require reaction times longer than two minutes. In most cases, 5 to 10 minutes of reaction time is sufficient.

Oxidized precipitates like iron and manganese are removed more easily in hard water than soft water. Sufficient time (approximately 30 minutes) is required for coagulation of the oxidation by-products. The preferred location for feeding potassium permanganate is the point that gives the longest contact time ahead of coagulation, usually at the intake of the plant.

Iron and Manganese:

1 mg/L of soluble iron requires 0.94 mg/L of potassium permanganate.
1 mg/L of soluble iron requires 0.84 mg/L of sodium permanganate.

1 mg/L of soluble manganese requires 1.92 mg/L of potassium permanganate.
1 mg/L of soluble manganese requires 1.71 mg/L of sodium permanganate.

Proper feed equipment specially designed to handle permanganate is recommended and available from Carus. For proper removal of Fe or Mn, the utility must have filtration or coagulation/filtration to remove the MnO2 and Fe(OH)3 formed during oxidation. In addition, alkalinity and hardness > 50 mg/L are recommended for proper coagulation of these precipitants.

Permanganate quickly oxidizes Fe2+ and Mn2+ in most cases without pH adjustment. The freshly precipitated iron or manganese floc will further adsorb metal ions and organic compounds while enhancing the effectiveness of the coagulation process.

• helps control tastes and odors,
• aids in the coagulation process, and
• acts as a substitute oxidant to chlorine in a disinfection by-product control program.

Knocke, W. R., Van Benschoten, J.E.. Kearney, M., Soborski, A., Reckhow, D. A., Alternative Oxidants For The Removal of Soluble Iron And Manganese. AWWA Research Report, (March 1990)

Ficek, K. J., Manganese Removal Using Potassium Permanganate in Low pH, Low Hardness Waters. AWWA Annual Conference, Washington D.C., (1985). Carus Form CX #3004

• Taste & Odor Control
• Iron & Manganese Removal

• Biosolids Odor Control
• Arsenic & Radium Removal

Carus Corporation has technical assistance available to answer questions, evaluate treatment alternatives and perform laboratory testing. Our laboratory capabilites include; Feasibility Studies, Treatability Studies and Analytical Services.

As an integral part of our technical support, Carus provides extensive on-site treatment assistance. We offer full application services, including technical expertise, supervision, testing, and feed equipment design and installation in order to accomplish a successful evaluation and/or application.

Standard feeders are designed specifically for CAIROX ® potassium permanganate. Various options and accessories are available to meet a wide range of applications. Custom-Engineered Feed Systems are complete, pre-engineered and prepackaged systems. They provide efficient, dust-free methods of storing, mixing, and feeding CAIROX ® potassium permanganate. System designs are customized to meet specific applications and customer needs.

During its more than 90-year history, Carus’ ongoing reliance on research and development, as well as its emphasis on technical support and customer service, have enabled the company to become the world leader in permanganate, manganese, oxidation, and base-metal catalyst technologies.

For further information on CARUSOL ® -20 Liquid Permanganate product characteristics and availability, and its treatment of iron and manganese in water, contact Carus Corporation at 1-800-435-6856.