A remote municipal wastewater collection system that is experiencing high levels of hydrogen sulfide.

Franklin Township Sewer Authority operates a 250,000 gpd pump station near a developed area of the township. Because adequate utilities (electrical power and water) were not readily available at this remote site, the pump station was left untreated. However, the Authority was concerned because periods of low flow at the station were producing hydrogen sulfide readings as high as 82 ppm, even during cool spring weather. Also, the Sewer Authority was receiving frequent neighborhood complaints about strong hydrogen sulfide odors coming from the station.

Due to the lack of adequate utilities, the use of chemical feed equipment for standard CAIROX ® potassium permanganate odor control treatment was impractical. Carus Corporation recommended CAIROX ®-CR, a newly developed product, to control hydrogen sulfide problems at this remote site. As the weather grew hotter in early summer, Carus and Franklin Township personnel conducted a field test of the new controlled release product at the remote pump station. During the field testing in the spring of 1999, approximately 40 lbs. of the CAIROX ®-CR extruded product was placed in a specially designed polyester mesh bag. No mixing of the product was required. The bottom of the bag was then lowered 6 inches below the water level at the inlet to the pump station. The next day a meter was installed to measure hydrogen sulfide in the station. Over the next 24 hours, H2S readings ranged from 0-12 ppm (down from 82 ppm), resulting in a 74% drop in average H2S levels compared to readings obtained in the spring.

Two days later, the CAIROX ®-CR product feed was increased by lowering the bag an additional 2 inches into the water, for a total submersion of 8 inches. No additional product was added to the bag. Five days later, the meter was re-installed and readings were again taken over the next 24 hours. Hydrogen sulfide levels during the period registered from 0-5 ppm. These levels represented an additional 23% drop in average hydrogen sulfide levels, for a total reduction of 97% compared to the spring readings. In fact, application of CAIROX ®-CR reduced hydrogen sulfide to below detectable levels for nearly 19 of the 24 hours and for extended periods of up to 9 hours.

During 10 days of testing at Franklin Township, no additional CAIROX ®-CR was added to the application bag. The testing used only about 1/4 of the original 40 lbs., or approximately 1 lb./day. The average treatment cost was about $3.50 per day.

The experience at Franklin Township clearly demonstrates the effectiveness of the controlled release CAIROX ®-CR extruded potassium permanganate in controlling hydrogen sulfide at remote wastewater sites. Based on such performance, practicality and cost effectiveness, the Franklin Township chose to continue treating their remote pump station with CAIROX ®-CR product. Hydrogen sulfide levels continue to be extremely low and customer complaints have been eliminated.

• Manholes
• Thickeners

• Lift Stations
• Clarifiers

• Toxicity Reduction
• Acid Mine Drainage

Sulfides and other organic and inorganic compounds can form in the biosolids handling operation of a wastewater system due to anaerobic conditions. These gases can be released during the dewatering step causing the rotten egg odor of toxic H2S and other sewage related compounds. Sulfides can react with moisture in the atmosphere to form acids, that will corrode equipment. Aqueous solutions of permanganate will destroy the odors caused by H2S, mercaptans, amines, and other organic nitrogen and sulfur based compounds and prevent the formation of corrosive acids. The result is a safe, odor-free environment that minimizes corrosion due to sulfides. Permanganate will not oxidize ammonia. In the treatment of sanitary sewage, biosolids are separated from the liquid. These biosolids are concentrated and dewatered using filter presses, centrifuges, or other devices. H2S is released during the dewatering operation.

Hydrogen sulfide measurements are made around the dewatering equipment. Permanganate (1% to 20% solution) is then applied at a convenient point either into the biosolids holding tank or directly ahead of the solids transfer pumps. The reaction with sulfides is immediate. Feed rates are adjusted to adapt to changing conditions such as flow and temperature. The direct injection of aqueous potassium permanganate solutions into the wastewater biosolids eliminates odors except ammonia.

For H2S:

For each part of hydrogen sulfide, 4-6 parts of permanganate are required. For biosolids odor control, testing usually starts at 100 ppm KMnO4 (10 lbs. per dry ton). The dosage is normally reduced to 5 to 8 lbs. KMnO4 per dry ton after the system is stabilized.

Employees are no longer subjected to toxic hydrogen sulfide and neighbor complaints about odors are reduced or completely eliminated.

Pisarczyk, K. S., Rossi, L. A., Sludge Odor Control and Improved Dewatering with Potassium Permanganate, 55th Annual Conference of the Water Pollution Control Federation, St. Louis, Mo. (Oct 1982). Carus Form CX #4005

Ficek, K. J., Potassium Permanganate Controls Sewage Odors, (1980). Carus Form CX #4007

Staff, Permanganate Treatment Brings Odor Control Success, WATER/Engineering & Management. Carus Form CX #4009

Pope, R. J. , Weber, R. A., Odor Control With Chemicals, Operations Forum, Vol.11, No. 4, (April 1994). Carus Form CX #3760

Carus Corporation, the CAIROX ® Solution System. Carus Form CX #4900 (1997)

• Taste & Odor Control
• Iron & Manganese Removal

• Industrial Wastewater Treatment
• 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 CAIROX ® potassium permanganate and its treatment for hydrogen sulfide (H2S), contact Carus Corporation at 1-800-435-6856.