Thermophilic bioprocessing has a range of definitions, particularly when applied to
waste treatment (Hamer and Zwiefelhofer, 1986). Virtually any temperature above 45 jC
has, on occasions, been described as thermophilic, but for pathogen inactivation, only the
temperature range between 60 and 72 jC can be considered to be potentially effective. At
temperatures only slightly more than 72 jC, process-mediating thermophilic bacteria are
themselves inactivated, placing an operational limit with respect to temperature. While a
temperature of 72 jC will, at appropriate residence times, inactivate many pathogens,
others are able to survive, particularly in the absence of significant hydrolytic activity, or
where dormant forms such as spores are formed.