Validating waste management equipment in an animal biosafety level 3 facility

Abstract

The Duke-NUS Medical School's animal biosafety level 3 facility is fitted with 3 types of equipment for waste decontamination: autoclaves, a tissue digester, and an effluent decontamination system (EDS). Validation of the effectiveness of the decontamination systems and process was done through simulated loads of waste. Biological indicators (BIs) were used to test the efficacy of the decontamination process. Geobacillus stearothermophilus log 106 was used for autoclaves and the tissue digester, while Bacillus subtilis and bacteriophages were used for validating the EDS. The loads tested in the autoclave included laundry, solid waste, and animal cages, with BIs placed in locations that were a challenge for steam penetration. The tissue digester was validated with frozen chickens from the supermarket, with BIs placed in the abdominal cavity of the carcass. The optimal weight of sodium hydroxide was that which achieved no growth in the BIs and, on visual inspection, no flesh or marrow on the bony remnants. Liquid waste from the shower, sinks, and downdraft table was routed to the EDS, which was validated with B subtilis and bacteriophage. Bleach was used for decontamination at a concentration >700 ppm of total chlorine. In high-containment facilities, factory and onsite testing and commissioning of waste management systems need to be supplemented by adequate validation processes to ensure the effectiveness of decontamination for the types and amount of waste generated in the facility. This is critical to ensure that no material leaves the facility until it is properly decontaminated.