NB: there are a few alternatives to composting to kill pathogens in sludge ... to be accurate with my posts:

I've attached an extensive document which gives lots of details on various methods. None are time based alone. The regimes are:

A) proven methods, time and temperature monitoring with record keeping, and indicator organism checking (for assurance, like E.coli). Ample science to support the assured process of time / temperature destruction of pathogens.

B ) non proven methods (low temperature), meet basic parameters (like VS reduction to show that something is actually happenings) followed by full pathogen testing (E.coli, Salmonella, virus, and helminth ova). Virus testing and helminth ova testing are very expensive tests and few labs in North America even do this. Full pathogen testing is done because non proven methods all have influence by site conditions and no assurance of process. The costs of testing full pathogens make this nearly impossible at remote and decentralized individual or community toilets. This is why Jenkins is all about batch thermophilic process... because heating and mixing a few times is many many times safer than leaving shit in a pile for years.

Again, one key question that nobody has addressed:

Is Susana (and the forum) a popular public access forum for people to share their opinions, or does it have purpose / a mandate to protect public health and guide development with this as a guiding principle.

If the first (public open forum) this forum is well populated with full spectrum of opinions, people can read and make their own mind up.

If the second (with mandate to protect human health), someone needs to step in and help draw conclusions and make statements.

If the second, Susana needs to define what compost means to them, with regards to their mission and mandate. Is it the rotting of organic waste in a pile to make soil conditioner? Or is it an engineered process with controls and critical check points to be sure to minimize risk and provide high confidence to low-skill, minimal PPE wearing operators, and un-informed end-user (subsistence farmers).

In the USA (and other countries) there is a an agency called the EPA which protects public health. Composting sludge is defined and regulated within. To minimize infectious disease transference, biosolids (even those treated anaerobically through industrial facility) need to be thermophilically composted to reduce risk to the point at which substance can be sold or used without restrictions.

www3.epa.gov/npdes/pubs/chapt_02.pdf
nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=200046QX.TXT

Is it in Susana's interest to define compost and composting to protect public health, or not?

As sometimes happens I wonder if this discussion is getting bogged down (excuse the pun) in semantics.

I have just looked up the word compost in an online dictionary and it says: "decayed organic material used as a fertilizer for growing plants".
As a gardener that seems to me a reasonable definition and it is one with which most people would be familiar.

At an earlier stage in this thread I notice that Dr Geoff Hill defines compost more technically: "The definition of compost is a material that has been thermophilically and mesophilically treated to reduce pathogens by 4 logs."

Obviously the risk is that the dictionary definition could lead CT owners or managers to think that CTs produce compost which is safe for growing food plants.

My company advises against the use of compost from toilets on food crops. Our assumption is that although harmful bacteria and viruses are likely to have gone as a result of one year's composting there is a risk of parasites surviving.

Dear Dean and others.
We are appreciative of the efforts made by varied team Members .
An important objective still needs to be done, is to how to ascertain that faecal sludge is safe, well secure to be used in application on land ie at agri farms.
Just for eg we have Scientists carry out 'bio assay' tests to test out safe waters by use of 'sacrificial fish'
I may be wrong to suggest, could we have some tests which can easily be done by practicing communities to ascertain this 'parameter'. Etc.
Well wishes for extending efforts.

Faeces "composted" at low temperatures has not decomposed.

The listed survival of helminths in the WHO standards for soil have no relevance to faeces. Clearly it has been shown many times that the survival time they have for faeces is much too low.

I'm not contributing to an irrational attack on researchers who are testing systems in use because someone else insists that there is some lengthy storage time that will kill all Helminths.

With respect to what Elizabeth says, that's all I am going to say.

Joe, I acknowledge that one study looked at 6 months and the other study looked at 12 months. However, neither of these provide useful data on how long an EcoSan compost should rest for, despite that system being available for 18 years.

Some quotes from "Inactivation of pathogens in EcoSan latrines"

It was found that pathogen concentrations were significantly related to time in months. As storage time increased, there was a reduction in log concentration of pathogens per gram of sludge.

Since EcoSan sludge has been found to still contain high Hookworm eggs, E. coli and Salmonella even after the waiting period of more than 12 months, protection during handling and use in agriculture is important. Storage time of 12 months or more is recommended.

What the community actually need to know is how long it takes to inactivate pathogens. We don't want to know that they are not all inactivated after 12 months. That is not a result.

What we need to know is how long it takes for die off of pathogens in decomposed human excreta. Not how long once the vault is closed, because there is an unknown period of time for decomposition to take place (especially of the contents at the top). I have been careful to say this all along, "pathogen levels reduce over time in decomposed human excreta", not something like "pathogen levels reduce over time in stored human excreta". Yet the study didn't measure decomposition. At what point in that 6 months or 12 months was decomposition complete?

One could say that because the pathogens weren't all inactivated after 12 months that this is evidence that they will never be inactivated, but that is an untested hypotheses. The scientist seeks to answer the question and in this case the testing should have continued well past 12 months, to model the pathogen survival curves. Why didn't it?

Seems to me the community remains in the dark. The users of these latrines don't know how long EcoSan compost should rest once decomposed and so the risk remains. How did the researchers come up with "Storage time of 12 months or more is recommended." I don't see the science to support that assertion. Conclusions need results that support them.

That it took 17 years to refute the 6 month "safe" storage period is a black mark on the sanitation community. That we still don't know how long it should rest is a travesty.

Whats worse is that apparently we haven't even moved forward on understanding conditions that influence survival of pathogens over time, especially temperature and moisture content in stored humus/compost. I want useful results, results that actually contribute to knowledge. The academics need to know our requirements and take these into account in their experimental design.

cheers
Dean

Question by me in my moderator role: I have the feeling that the last few posts have focused on a slightly different topic than what the thread title suggests. What do you think, should I split them off into a separate dedicated thread with a new title (with adding links in both directions)? Or should they stay here?

And I can see a bit of tension building. Please everyone try to remain cool, calm and collected (and friendly) towards each other even if opinions may clash. We want this forum to be a friendly space. Thanks.

Yeah ok Dean. They were tested after 1 year of storage. Do come back to discuss further after you've actually read all three papers.

And it is quite insulting to say things about academics who are taking measurements to test things that you say are happening based only on assertion.

You've no idea what's happening. How could you - you haven't tested anything.

Joe, actually the EcoSan toilets in that paper were rested for only 6 months.

After using the latrine for defecation for 6 months or more, the latrine pit or vault is sealed for another 6 months to allow the pathogens to be killed.

Not surprisingly the results showed this not to be the case, but those results don't take us forward in any way:

More research is required to check if the helminths identified in EcoSan latrines are deactivated after the 6 months treatment period.

So who came up with the notion that Ascaris would be killed from 6 months slow composting? Seems bizarre to me that despite academic literature and WHO guidelines that this was promoted from 2001 till now.

OMG... reading the Malawi paper it gets even worse...

EcoSan latrines owners, where they were found to store their harvested sludge behind their households on bare ground. This led to uncontrolled spreading of manure around the household environment increasing the chances of infection

The WHO guidelines report a normal maximum survival in soil of 2 years for Ascaris (table 3.9). If there is still inadequate research results available now in 2019 to satisfy us then this community has real problems. Problems with academics not knowing what to research, problems with even knowing what conditions induce absolute maximum survival, resulting in an ignorance that allows some practitioners to recommend 6 months resting for EcoSan... Ignorance among sanitation experts who use confirmation bias to justify their position because the work has not been done to objectively quantify the time it takes for die off?

I will repeat myself. Pathogens reduce over time in compost. The scientific literature is very clear that pathogen levels reduce over time in decomposed human excreta.

If I am wrong, or the academics have not yet settled on time periods adequate for producing safe product, then the simple conservative approach is just to extend the period until we have settled it. I'm happy with 2-3 years after decomposition has occurred, but would be willing to design my systems to have 3, 4 or 5 years rest. Joe, you might want to believe that this

is an impossible scenario that is never going to happen anyway

but I disagree. Even twin pits can be designed to rest for that period.

Bill Gates is investing millions of dollars into sanitation, yet we, the sanitation community, apparently don't even know how long compost (decomposed faeces) need to rest before being safe to handle or use in crops? Wow, no wonder ascaris are rampant in Malawi and all those other counties that are relying on the international advisors and academics for sanitation solutions. Yet in 2019 we still don't know how long an EcoSan compost should rest for, despite that system being available for 18 years?

Wow.

Again, maybe you have managed to find a magic "sweet spot" whereby systems that should not logically work somehow do.

I think more likely you operate somewhere that a) does not have endemic nasty pathogens b) has easily accessible multiple barriers including gloves, good healthcare and clean water to wash hands.

The question is then not really about what you call your system - lots of clever names have been suggested - but that systems are taken to be working in "optimum" conditions and then applied to areas where none of the barriers exist. Where the consequences of unmeasured application to vegetables can be much more serious.

Personally I can see no reason to do that anywhere. The gains in terms of the nutrients from the faeces are much lower than the potential costs in terms of infection.

This debate should be measured by the time eternal question. "What are the alternatives ? " There certainly are alternatives but often you need to take into account the cost factor. If the more comprehensive systems are not affordable then we are faced with the worst scenario-
no system at all.
I started building Composting Toilet Systems in 1979 and to date I have only ever had one call out to a system that wasn't functioning. It wasn't mine, but it alerted me to problems associated with mixing urine with faeces and this prompted me to market only urine diverting pedestals.
Most people I deal with use the Pedestals for collection only with the partially composted material stored separately and interned to gardens when considered (unmeasured) to be appropriate. These people are not concerned with pathogen levels as they are dealing with their own family members and some even use the composted material for vegetables. I say composted because it is broken down, does not have odours and is easily spread. Compare this to a flushing district sewer main and the resultant effluent into the Ocean. My local sewer plant uses reverse osmosis and still there is a sludge on our beaches nearest the outfall. They say this is state of the art.
I would like to see more time putting a positive spin on this, rather than heaping criticism on what I consider a suitable and often necessary alternative, regardless of the semantics of appropriate titles.

Dean - most of these points are not really points and have already been established.

Risk is estimated by considering Quantitative Microbiological Risk Assessment (QMRA) and is assessed against standards for acceptable numbers of Ascaris infections.

I invite you to look at the papers I added today to the thread called "Knowledge, attitudes and practices on use of Fossa Alternas and double vault urine diverting dry (DVUDD) latrines in Malawi" here where all of these are discussed in great detail.

In brief, 1 year of storage of these facilities in Malawi was not sufficient to get to safe levels. And there was no measured difference between the ecosan (whether or not one considers them to be "composting toilets" is an open question, perhaps) and other latrines.

There is no guarantee that storage will reduce pathogens to safe levels - whereas if all of the material reaches high temperatures they will be destroyed. Because basic microbiology.

Telling people that faeces from "composting toilets" are somehow safe to handle after six months, one year or even two years flies in the face of the available information.

And we don't know what could theoretically happen after five years. Which is an impossible scenario that is never going to happen anyway.