Revision history [back]
The problem
• a shitty field
• a shortage of space
• lots of people
Possible solutions
• Don’t use it – but the alternative may be worse so Chris will have to weigh up risks
• Best solution – scrape if off – may not be possible – we are talking about say 20cm and even then no guarantee that there is not some pollution left
• Next best – cover it – same problems as scraping it off – a lot of earth
In-situ treatment needs:
o High pH – lime would help but would not disinfect only reduce the time required by a modest percentage through raising the pH
o High temperature – but Feachem et al quote for composting figures of 62C for 1 hour, 50C for 1 day, 46C for 1 week, 43C for 1 month and 42C for 1 year for the inactivation of all excreted pathogens with the possible exception of Hepatitis A
o Low humidity – almost certainly a challenge in Sri Lanka and little that can be done?
o Time – measured in months, see above – we assume that Chris does not have this luxury
o So on balance any on site treatment may be tokenism with the exception of scraping or covering
Karen and I are well aware that we have not come up with a magical solution, but unless someone else does, perhaps the best we can offer is confirmation that one does not exist - apart from scraping or covering.
Tim Foster
2 |
No.2 Revision
|
|
The problem
• a shitty field
• a shortage of space
• lots of people
Possible solutions
• Don’t use it – but the alternative may be worse so
Chris
you
will have to weigh up risks
• Best solution – scrape if off – may not be possible – we are talking about say 20cm and even then no guarantee that there is not some pollution left
• Next best – cover it – same problems as scraping it off – a lot of earth
In-situ treatment needs:
o High pH – lime would help but would not disinfect only reduce the time required by a modest percentage through raising the pH
o High temperature – but Feachem et al quote for composting figures of 62C for 1 hour, 50C for 1 day, 46C for 1 week, 43C for 1 month and 42C for 1 year for the inactivation of all excreted pathogens with the possible exception of Hepatitis A
o Low humidity – almost certainly a challenge in Sri Lanka and little that can be done?
o Time – measured in months, see above – we assume that
Chris does not
you don't
have this luxury
o So on balance any on site treatment may be tokenism with the exception of scraping or covering
Karen and I are
I'm
well aware that we have not come up with a magical solution, but unless someone else does, perhaps
the best we can offer is confirmation that one does not exist - apart from scraping or covering.
Tim Foster