Thermal Inactivation of Causative Agent

Many materials of composting contain some seeds and causative agents that are harmful to human beings. Urban sludge is a typical material that carries causative agent. During composting, we can control the growth of those microorganism through heating. Therefore, one advantage of high-temperature composting is that this process can devitalize seeds and causative agents.

 If the enzyme of cells got devitalized under high temperature, the cells would die soon. The thermal inactivation of the enzyme is not invertible. Without enzyme, cells would lose functions and die soon. Only a few enzymes can still be alive under high temperature.

Some researches indicate that high temperature can kill the pathogen. Usually, spore bacteria can be inactivated in 60 ~ 70 ℃ ( under hot and humid condition) for 5 to 10 minutes. Through heating sterilization, the pathogen in sludge can be eliminated if it is under the temperature of 70 ℃ for 30 minutes. However, at a lower temperature (50 ~ 60 ℃), some pathogens need 60 days to be inactivated. Thus, in the process of composting, it is a must to make sure temperature is above 60 ℃ for some time.