Inactivation of Bacillus spores in decontamination wash down wastewater using chlorine bleach solution.

Bacillus anthracis spores are highly resistant to disinfection. The effectiveness of sodium hypochlorite (bleach) solution for the inactivation of Bacillus atrophaeus subspecies globigii spores (a surrogate for Bacillus anthracis) in wash down wastewater was evaluated by a series of bench-scale and pilot-scale experiments. The wastewater was generated from a simulated decontamination of interior laboratory surfaces and personal protective equipment. A concentration of approximately 5% ( v/ v) bleach solution was adequate for a ≥7 log10 inactivation of Bacillus spores spiked in wastewater after 10 min of contact time at room temperature. This sodium hypochlorite dose is less than the U.S. National Response Team-recommended formulation of 10% ( v/ v) bleach solution with 10% ( v/ v) vinegar. For the wash down waters evaluated, the addition of vinegar was not required. Inactivation of Bacillus spores was faster when a detergent was added to the wash down waters tested. [ABSTRACT FROM AUTHOR]