Discussion
107
from microbiological contamination after washing, peeling and cooking. But because of the increasing
use being made of raw vegetables as food it was now necessary to take into account these changing
habits.
E. Lund, Denmark.
In the examination of sludge sample from digesters where the average retention time was 3 weeks
and the temperature 50°C I have repeatedly found poliovirus (types 1,2 and 3) that could not be
vaccine strains. Dr. Sproufs comments on the minimum retention time is important, because when
you take digested sludge in the laboratory and treat it for 24 hours at 50°C, you will probably not
find virus.
107
from microbiological contamination after washing, peeling and cooking. But because of the increasing
use being made of raw vegetables as food it was now necessary to take into account these changing
habits.
E. Lund, Denmark.
In the examination of sludge sample from digesters where the average retention time was 3 weeks
and the temperature 50°C I have repeatedly found poliovirus (types 1,2 and 3) that could not be
vaccine strains. Dr. Sproufs comments on the minimum retention time is important, because when
you take digested sludge in the laboratory and treat it for 24 hours at 50°C, you will probably not
find virus.