Evaluation of USEPA time-temperature requirement for Escherichia coli destruction by standard culture method and flow cytometry

摘要

USEPA time-temperature requirements for fecal coliform destruction were evaluated by both the standard culture method and flow cytometry to investigate if insufficient thermal treatment was the reason for fecal coliforms reactivation observed in a field digester. Results showed that complete inactivation (8-log) of cells can be achieved well below the regulatory requirement. Destruction was found to be permanent where no recovery of viable cell was observed upon further storage up to 2 weeks. Overall, time-temperature treatment is found sufficient to completely inactivate coliform cells but stressors prior to thermal treatment may increase their resistance.