What temperature and time to kill pathogens?

  • paulv
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What temperature and time to kill pathogens?

Is there a recommended temperature and time to heat fecal matter to kill pathogens and make it safe from a human health perspective?
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  • JKMakowka
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Re: What temperature and time to kill pathogens?

In the USA you will need to treat it according to EPA "Class A (EQ) biosolid" regulations, which includes methods for heat pasteurization as far as I know.

Krischan Makowka
Microbiologist & emergency WASH specialist
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  • nazimuddin
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Re: What temperature and time to kill pathogens?

I have also the similar question:I am working in Mongolia on fecal composting. Lowest temperature is -40 degree C.

Under which low temperature e.coli or salmonella can be killed or partially destroyed?

Thank you

Nazim

Sayed Mohammad Nazim Uddin, PhD
Post-Doctoral Fellow & Sessional Instructor
University of Victoria
Victoria, BC, Canada
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Re: What temperature and time to kill pathogens?

As far as I know, low temperatures will for the most part (save for some cellular damage due to ice crystals forming) not really kill any bacteria. It will prevent them from multiplying but otherwise pretty much conserve them.

What could be interesting in a cold but dry country like Mongolia though might be sun based UV treatment. I am speculating a bit here, but under the right conditions and with the cellular DNA repair mechanisms pretty much shut down due to the cold, direct sunlight (e.g. limited cloud-cover) especially at higher sub-tropical altitudes might be quite efficient in killing bacteria.

Krischan Makowka
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  • F H Mughal
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Re: What temperature and time to kill pathogens?

The attached paper on Bacterial Die-off Kinetics in WSP might help.

F H Mughal

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  • groverhmc
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Re: What temperature and time to kill pathogens?

I hope this graph helps you to have an idea.



Source: Decentralised sanitation and reuse. Lens, Zeeman and Letinga 2001

Kind regards

Grover

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  • F H Mughal
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Re: What temperature and time to kill pathogens?

Dear Mr. Grover,

That is a very useful and interesting graph. Could you kindly upload the full publication?

Regards,

F H Mughal

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  • paulv
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Re: What temperature and time to kill pathogens?

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Re: What temperature and time to kill pathogens?

Thanks, pal. I appreciate

Best,
F H Mughal

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Karachi, Pakistan
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  • smecca
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Re: What temperature and time to kill pathogens?

Yes, most bacteria will go dormant at such temperatures. I just noticed a pathogen kill graph posting that should help on the question. In the S-Lab at Providence College US we are experimenting with several options for killing pathogenic bacteria including: SOLDIS, NH3 from urine, slow sand filtering and carbon filtering (this is just getting underway. Our work is related to our Microflush toilet which produces a small amount of blackwater that we are seeking to treat ( forum.susana.org/forum/categories/106-us...mit=12&start=12#5616 ).
There is a project in the UK on a nano membrane technology and this has been reported on the SuSanA forum.
( forum.susana.org/forum/categories/105-pr...nfield-university-uk )

Stephen Mecca, Ph.D.
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Department Engineering-Physics-Systems
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Providence College
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  • maryanneleblanc
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Re: What temperature and time to kill pathogens?

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Re: What temperature and time to kill pathogens?

Just a note of caution - even if those temperatures are definitive, the whole volume of the faeces would have to be raised to that temperature for that time for the pathogens to be completely sanitised.

Using a temperature probe to find areas of high temperature may not be enough if there are also areas where the pathogens survive. It will depend on the treatment system as to whether this is a problem in any given situation.
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