Organic Waste Recycling

Composting 91

Figure 3.1 Influent of time and temperature on selected pathogens in night soil and
sludge (Feachem et al. 1983; reproduced by permission of the World Bank). Note: The
time represents conservative upper boundaries for pathogen death that is, estimates of
time-temperature combinations required for pathogen inactivation. A treatment process
with time-temperature effect falling within the “safety zone” should be lethal to all
excreted pathogens (with the possible exception of hepatitis A virus – not included in the
enteric viruses in the figure – at short retention time). Indicated time-temperature
requirements are at least: 1 h at • 62 °C, 1 day at • 50 °C and 1 week at • 46 °C

Safety zone

Vibrio cholerae

Entamoeba

histolytica

Ascaris

salmonella

Taenia

Shigella

Enteric

viruses

Temperature (°C)

Time (h)