Christophe wrote:Did67 wrote:For example, in an anaerobic digestion plant, all "biological" waste (kitchen scraps, slaughterhouse waste) must be pasteurized before entering the digester, in order to be able to spread the digestate at the outlet on commercial crops.
I had also heard that the digestate had to be "disinfected" after leaving the digester for use in spreading ...
Pasteurization is done at high temperature 60-70 °>
breathing then gradually raises the temperature to 60 ° C - 70 ° C, leading to the replacement of mesophilic microorganisms by thermophiles and thermo-tolerants.
by their breathing, micro-organisms deplete the oxygen of the mass in composting and make the environment anaerobic. Anaerobic germs then develop, leading to a lowering of the temperature because their metabolism is less thermogenic. They are also responsible for the release of foul-smelling volatile compounds (methane, ammonia, hydrogen sulfide, etc.).
To avoid this putrefaction, it is necessary to restore the aerobic conditions of the medium (see aeration below). Thus it will be possible to prolong the fermentation at high temperature. Pathogens, parasites and weed seeds will be destroyed by the high temperature, unpleasant odors will be avoided, decomposition will be faster. As soon as the temperature no longer increases after aeration, it can be considered that the degradation is complete.
Source: wiki
Using wastewater directly does not destroy pathogens and can be transmitted to plants and then to humans.