My reply will not address the storage of dry matter, but the secondary treatment of waste from both UDD and other waterless toilets.
I'm not giving myself out as an expert, and we learn by trial and error as we are the only company in South Africa currently subscribing to the composting process of human waste.
We have been composting the waste from our "sawdust- based" waterless toilets for the past 24 months with great results. We maintain temperatures of between 45 - 55 C during the first 8 days of the composting process which effectively kills pathogens and latent ova. The temperatures can be maintained for longer - depending on the other materials you use in the process (C/N) and the volume of liquid (urine, grey water) you use in the process.
Because we do these processes on a decentralised basis, and specifically in informal settlements we have now engaged with a SA University to assist with a study where we can combine the composting with a biogas process. Biogas digesters optimal performance takes place at approx 32-34C, and the temperature isn't high enough to neutralise pathogens.

I'm not going to elaborate on the topic, but we are interested in knowing if other companies and/or universities are use composting and/or biogas as a field of study (we are familiar with the SOIL study in Haiti - Berkeley Univ), and other research material on pathogens and their behaviour under different temperatures.
A collaborative study may provide different outcomes, and possible solutions to northern and southern hemisphere challenges.

Hi KaiMikkel,

Just in case you do not know this publication:
www.ecosanres.org/pdf_files/Microbial_Ex...logies_&_Systems.pdf
I guess the best overview on microbial exposure and hygiene studies.
In Annex 7 not a graph but all related literature to UDDT

Best regards
Claudia

A UDDT is not necessarily a dry toilet. Water can be added from handwashing or in doses or misdirected urine (it happens). It then can become a composting toilet, particularly with the adding of composting worms and soil fauna... If the container is big enough it can be subject to long term composting. There is data on this, see for example www.compostera.eu/tests.html .

CWendland - thanks for your response (and thanks everyone else as well!). However, the guidance I was looking for isn't met by either of the documents you referenced (both of which I did have previous knowledge of). What I was hoping for was something in the way of new information. So, to reiterate, is there a similar graph (or other graphical data presentation) that shows the results of a long term study into what happens when desiccated feces is left undisturbed in ambient conditions for multiple years in a northern climate? I'm curious about how effective a long term "leave it and forget it" approach to treatment might be. What I mean is five years in storage. Or ten. Or even more. Obviously, the time of storage becomes impractical at some point (one only has so much room for storage) but surely five years is doable for, say, a small family or for even just a single person or couple.

Another way of approaching this might be to look at how long an ascaris egg or helminth egg or e Coli, etc., can survive if prevented from becoming "wetted". Obviously ambient humidity levels fluctuate but I'm not knowledgeable enough to know whether high ambient humidity levels on their own meaningfully contribute to prolonging the dormant lifespan of these pathogens.

It is often mentioned that desiccation is not a form of "treatment" but is that really true under a scenario of long term storage? I suspect that most studies into this topic were looking at fairly narrow scenarios, like a double vault UDDT or co-compositing scheme - some deliberate "means to an end" where there were limitations (like only having two vaults or needing to produce a marketable or usable product in as short a time as possible, etc.) and where the "end" was achieving efficient pathogen inactivation (leaving desiccated feces around for multiple years probably isn't seen as very "efficient"). Plus, I doubt that the "what if" proposition in most of these assumed cases was not, "what if we just leave this desiccated feces alone for five years in a northern climate?" or "what if we leave this <insert pathogen> alone in a desiccated state for ten years, what happens?" After all, in many if not most scenarios, storage times of this length are impractical, so if it exists the kind of study I'm inquiring about may not have been conducted under the scenario of a sanitation scheme but, instead, perhaps as part of some work into basic bacteriology or pathology or the like. I'm just guessing here, of course.

So, another way of asking this is: is there a storage time (practical or not in length) under ambient conditions in a northern climate that will render desiccated feces safe to handle? And, is there an easily understood graphic that displays what this length of time is?

Hi Ross and ecosan fans

from the World Health Organization there are Guidelines from 2006:
Guidelines for the safe use of wastewater, excreta and greywater in agriculture Vol 4
www.who.int/water_sanitation_health/publications/gsuweg4/en/

In tables 1-3 they give details on treating urine and faecal matter in cold and warm climate.
Still I agree that an additional post-treatment increases safety that it why we recommended post-composting for the dried faecal matter from the faecal chambers (even of the double vault system).

A number of useful Information on UDDT you also find here:
www.wecf.eu/download/2015/November/Web_2015UDDTManual.pdf

Claudia

Hi Tore,

There are new papers on pathogen die off. The chart refers to relatively constant temperatures.

That insert is ready to go. It is just pointed away from the camera.

Best wishes,
Chris

I see your response in my email but I was not able to find it SUSANA. I printed it below.
This is the only time/temperature chart that I have been able to locate. If anyone has friends in the biology department at a university there is a great project for grad students to amplify on the chart by looking at how much time at lower temperatures it takes to sanitize feces. The chart I use in my website only states temperature for a period of time. Does that mean continuous or can it be several hours each day? Need to dig deeper.
As for long term at ambient temperatures I don't know. Below freezing some bacteria can last years. If you have an insulated enclosure with a window to the south you can still get high temperatures inside when the outside temperatures are brutal. There is such a fear that even one bacteria remains alive that many organizations go way overboard in their recommendations on sanitizing feces.

Ecowaters - Regarding the graph that you referenced earlier (thank you for that BTW), I'm curious if you can point me in the direction of a similar graph (or other graphical data presentation) that shows Time/Temperature requirements needed to kill pathogens in desiccated feces where the time frame is measured in multiple years and the temperatures are ambient (as opposed to artificially elevated). What I would like to know is how many years in a northern climate desiccated feces needs to be stored (assuming year-round, outside storage in a water-tight HDPE barrel) before the contents can be considered safe. I understand that it is ECOSANRES' recommendation that desiccated feces undergo an extra biological treatment step (like co-composting). However, what if such a step is unwanted or otherwise impractical? Is there a period of time (measured, say, in multiple years) that desiccated feces can be dry-stored in ambient conditions that will make it safe to handle and use?

Thanks for picking up the citation.* The same chart is under "Sanitation" subheading "Sanitize Feces and Urine" and there he is cited. I will add the citation to the first chart. Are you familiar with any other time/temperature studies to eliminate the pathogens?
On the basin that you show I assume that you would have to drill a 4" hole in the center for the feces and a hole in the urine side.


+++++++
* Note by moderator: Tore is refererring to this statement by Chris in the other thread: Also, on your webpage, I recommend you cite Feachem on that graph and maybe try to find newer sources.

Comment by moderator: I have now split off the last few posts into a new thread as the conversation moved away from the original topic. (Kai: no worries about "hijacking" a thread - that's what I am here for - to split off posts into new threads as the need arises. )

I also wanted to point out two previous threads that were also talking about the temperature-time graphs to kill pathogens. They are:
- Strauch (1991) 'Pathogen Safety Zone Graph' - collated the thermal death curve of a number of enteric organisms - forum.susana.org/technologies-for-treatm...of-enteric-organisms
- What temperature and time to kill pathogens? - forum.susana.org/technologies-for-treatm...me-to-kill-pathogens

(but I don't think they fully address Kai's question about multiple years in cool temperatures)

As a broad, sweeping statement: I would never rely solely on treatment (time, temperature) but always think of a multiple barrier approach to reuse or disposal. The more barriers the safer it is.

Regards,
Elisabeth

Ecowaters - (I don't want to hijack this thread so please feel free to contact my privately.) Regarding the graph that you referenced earlier (thank you for that BTW), I'm curious if you can point me in the direction of a similar graph (or other graphical data presentation) that shows Time/Temperature requirements needed to kill pathogens in desiccated feces where the time frame is measured in multiple years and the temperatures are ambient (as opposed to artificially elevated). What I would like to know is how many years in a northern climate desiccated feces needs to be stored (assuming year-round, outside storage in a water-tight HDPE barrel) before the contents can be considered safe. I understand that it is ECOSANRES' recommendation that desiccated feces undergo an extra biological treatment step (like co-composting). However, what if such a step is unwanted or otherwise impractical? Is there a period of time (measured, say, in multiple years) that desiccated feces can be dry-stored in ambient conditions that will make it safe to handle and use?

Heat and time are wonderful ways to kill the pathogens. There is a chart on my website www.sanitationhealthintransition.com that shows the time and temperature required to kill pathogens and make the product available as a soil conditioner.

It was by Aussie Austin of CSIR in South Africa. I think it is referenced in one of my books, because we met him at the GTZ-organized eco-san conference in Bonn. I'll try to dig it up.

It confirmed what my coauthor, David Del Porto, suspected about dried feces, even with lime.

It further supported Ecosanres's position that endproduct from UDDTs (versus composting toilets and composting, a biological process) must have secondary processing, ideally composting.