CAIROX Potassium Permanganate - Case Study

BACKGROUND

The Carbondale Water Treatment Plant (Carbondale, Illinois) with a design capacity of 8 MGD and an average flow of 4.6 MGD draws its water from Cedar Creek Lake. Because of moderately high raw water TOC levels (4.3 - 6.5 mg/L) and low alkalinity (36 - 40 mg/L as CaCO3), Carbondale is required to attain 45 percent TOC removal under the Disinfection/Disinfection By-Product (D/DBP) Rule. Based on their HAA and THM formation potentials (80-200 and 140-260 μg/L respectively), effective treatment is required, especially during summer months when temperatures are high and DBP formation reaches its peak. Carbondale personnel investigated a number of treatment options to minimize DBP formation and proactively achieve the Stage 2 limit of 30 μg/L for HAAs. These options included replacing chlorine with CAIROX® potassium permanganate as the pre-oxidant. In addition to DBP control, pre-oxidation with CAIROX potassium permanganate was evaluated for manganese, and taste and odor (T&O) problems.

CAIROX EVALUATION

The evaluation of CAIROX potassium permanganate was conducted in the Spring and Summer of 1999. By using CAIROX as the pre-oxidant, and still feeding chlorine above the sludge blanket, HAA levels were maintained below 30 μg/L even at elevated water temperatures, a result not obtained with chlorine alone1.

CONCLUSIONS AND OBSERVATIONS

CAIROX potassium permanganate effectively:

• Replaced chlorine as a pre-oxidant.
• Controlled HAA formation in the plant and distribution syste m.
• Lowered pre-aeration levels of THMs.
• Controlled periodic T&O and Mn episodes.