Selection of surrogate pathogens and process indicator organisms for pasteurisation of municipal wastewater—A survey of literature data on heat inactivation of pathogens

Pasteurisation is an alternative to other disinfection processes such as chlorination, ozonation and UV treatment. It does not produce harmful by-products and may have a lower pre-treatment requirement than other disinfection processes. Pasteurisation has been trialled and implemented in California under their “Title 22” regulations but there is a lack of peer-reviewed scientific literature to support the selection of appropriate surrogates and indicators for the validation of pasteurisation performance. This paper provides a brief review of the available knowledge on the heat inactivation of enteric bacteria, protozoa, viruses and helminths to inform the selection of appropriate surrogates and indicator organisms for pasteurisation disinfection of municipal wastewater. Based on review of the available literature, native Escherichia coli may be a reasonable surrogate for most organisms of interest, as most of the tested bacteria in the literature displayed a greater sensitivity to heat. Escherichia coli may also make a suitable surrogate for protozoa, helminths and some viruses as these have a higher sensitivity to heat than E. coli. Enterococci and FRNA phage (MS2) were found to be less heat sensitive than E. coli, most viruses, and the tested protozoa and helminth species, and could thus make more conservative surrogates for these pathogens.