438 Organic waste reuse and recycling: technology and management
Runoff from a land treatment site might be a potential pathway for pathogens
transport; but this is not a problem in RI system. Groundwater contamination
has the highest potential for RI system due to the high hydraulic loading rate
and coarse texture of the receiving soils.
Table 8.15 Tentative recommendations for excreta storage periods in warm climates
Storage period Hygienic quality acheived
2 days Inactivation of Clonorchis and Opisthorchis eggs
1 month Complete inactivation of viruses, bacteria and protozoa
(except, possibly, Salmonella on moist, shaded soil);
inactivation of schistosome eggs
4 months Inactivation of nematode (roundworm) eggs e.g. hookworm
and whipworm (Trichuris); survival of a certain percentage
(10-30%) of Ascaris eggs
12 months Complete inactivation of Ascaris eggs
From Strauss (1986); reproduced by the permission of IRCWD
Figure 8.13 Pathogen survival on crops vs. vegetable growth periods in warm climates
(from Strauss 1986; reproduced by permission of IRCWD, Switzerland)
1) Determined under widely varying conditions
2) Maturation period from transplanting or from sowing if not transplanted1