Inactivation of legionella pneumophila by potassium permanganate

Potassium permanganate (KMnO₄) was investigated for its ability to inactivate cultures of agar‐grown Legionella pneumophila in a phosphate buffer (pH 6.0 and pH 8.0) at 7°C At pH 6.0, significantly higher inactivation rates, k values, (0.300 log₁₀ reduction min⁻¹ of L. pneumophila were observed compared to those at pH 8.0 (0.032 log₁₀ reduction min⁻¹). By exposure to 5.0 mg L⁻¹ KMnO₄ more than 99% (2 log₁₀ cfu mL⁻¹) reduction in the bacterial numbers was achieved within 10 minutes at pH 6.0; however, at pH 8.0, at least 60 min was required for 99% reduction. KMnO₄ was significantly more effective at 5.0 mg L⁻¹ compared to 2.5 and 1.0 mg L⁻¹. Water systems with KMnO₄ may gain disinfection credits as proposed by the U.S. Environmental Protection Agency.