muench wrote: Oh and I still disagree with Florian's "laissez-faire" approach when it comes to definitions of terms.

Well, this discussion illulstrates your point well, Elisabeth, so I guess you're right. Indiscrimate use of terms results in a lot of confusion. But then, Joe could really have made clear by now what exactly he means when talking about ecosan.

A few more reactions to Joe's comments here.

joeturner wrote: I am not suggesting that the risk should be 0 and the studies I have pointed out do not work on that basis. In fact the way to assess systems microbiologically is using Quantative Microbiological Risk Assessment which is based on acceptable dose rates, which is calculated by the socially acceptable number of infections in a community.

We have a quite detailed WHO guideline, which precicely uses these concepts to define health based targes and deduces standards and guidance on reuse of excreta. All the talk about multi-barrier systems is based on these guidelines.

joeturner wrote: It is possible to have toilets and even improved sanitation but without standards to determine when faeces is treated, it is impossible to say whether any system is really safe.

Again here is your exclusive focus on treatment (in toilets). UDDT toilets (asuming we still talk about this) are just part of a system. The complete system involves other treatment steps (like your prefered "meso-scale composting") or other protection measures (e.g. the ones listed by Christoph). You have to look at the whole system to determine if it's safe or not. Only looking at one component of the system, the toilet, is nonsense.

To come back to the example of Europe. As I said, the treatment is not safe at all and wastewater treatment plants discharge quite a lot of pathogens to the surface waters, but still the whole system certainly is quite safe. Why? Not because we have no pathogens in wastewater, as you assumed (we do!), but because plenty of other barriers are in place. The most important barrier is that nobody drinks directly from rivers, but that all drinking water is disinfected. Another safty measure is that bathing waters are monitored and flagged red when risks are present. And in some situations when it is really needed for safety, wastewater is indeed disinfected (e.g. when the discharge point is just upstream of a popular bathing spot).

So, treatment is just one safety measure in a system of multiple barriers. The decision on the treatment performance (pathogen removal rate) needed depends on the other components of the system and on economic and social considerations. Sometimes this may be 100 % pathogen removel, sometimes not.

Christoph, I am talking about any system of dispersed sanitation whereby users collect, treat and handle their own faeces.

Of course ecosan systems are not limited to such systems, as other have pointed out, but even such systems can be perfectly safe. E.g. a familiy owned UDDT toilet, where users store feces removed from chambers for addtional time before reusing it, or reuse it directly in the way Christoph described it, or just bury it somehwere in the garden.

Why this can't be a safe system? The critical part is that people have to handle fecal material which may still contain some pathogens, agreed. But handling dried fecal material, that has been in a chamber for half a year without addition of fresh feaces, is much less dangerous than cleaning a toilet when a family member has diarhoea, or changing diapers of your sick child. So why should we trust in people being able to wash their hands after cleaning their toilet, but not after removing dried feces from a vault?

Btw, same is true for reuse practice. People handle all sorts of very dangerous stuff (pesticides, fertilizers) when growing crops. It's commonly accepted that the risk can be reduced to acceptable levels by appropriate protection measures. Why should this be different for fertiser containing some residual pathogens?

UDDTs are designed primarily to do three things when it comes to faeces: to contain the faeces, to dry them and with the addition of woodash (high pH KOH) following each defecation, reduce flies, odor and pathogens. Once one of the 2 vaults is full it is topped up with woodash and left for 6 months. The risks in emptying such a toilet (each vault is emptied once every 12 months) are much lower than emptying pit latrines and septic tanks that preserve pathogens in the cool moist/wet environment. Once emptied the dried mass from a UDDT is then taken to a green compost to undergo thermal treatment up over 50-60 degrees celsius. The UDDTs in the Sahel countries and other dry and hot climates are even greater successes since they become almost pathogen-free within just a few months under the furnace-like dry conditions within the raised above-ground vault. Fossa alternas and Arbor loos are soil-composting ecosan toilets and also are given long cycles (one year and upwards) to reduce pathogens. The intestinal bacteria are no competition to the adapted and aggressive soil bacteria plus all the other organisms in soil. The eggs of helminth worms can theoretically persist in most environments but will die off at temperatures above 60 degrees celsius. But with high pH (from woodash), dryness and temperature ca 45 degrees, they can be killed off. www.sciencedirect.com/science/article/pii/S0043135412004101 . No other sanitation system comes close to UDDTs in the fight against Helminth parasites. That we have upwards of 2 billion humans that live with round worms is living proof that our hygienic practices in high exposure areas require much improvement.

In cases of patients with dangerous viruses like Ebola, Coronaviruses (SARS), Polio, etc. toilets with containment and heat are necessary (eg dry incinerator toilets www.siriuseco.no/en-us/frontpage.aspx) in order to provide 100% safety from faecal transmission. But these are not available or affordable in most parts of the world. So to provide both safe containment and treatment, the brick vault UDDT toilet combined with heat treatment using hot coals to reach temperatures of over 60 celsius in the vault would be an appropriate methodology to eliminate transmission via faeces. This to my knowledge has not yet been tried at scale. Along with sterilized surfaces and hand-washing transmission would be further reduced.

I apologise for dribbling. Are all dispersed systems ecosan? No. Are all ecosan systems dispersed? Yes - because I do not consider meso-scale composting to be ecosan. I think the problem is that they are dispersed and unmonitored.
I have seen a study looking at the risks to sanitation workers from emptying UDDTs, I will try to find it again tomorrow - the point is not whether gloves reduce the risks but whether the risks are reduced to acceptable levels.

Unless there are agreed standards of risk, I cannot really see how anything can be said other than that relative risks are reduced to one set of at-risk groups.

I think meso/medium/community/village scale sanitation is possible but that small unmonitored dispersed systems are not killing pathogens to safe levels. Small/household scale systems which claim to be treating faeces are not.

I would also point out that I was responding to the blog from the Gates Foundation (see sanitation.joetnr.net/sanitation-good-in-parts/ and forum.susana.org/forum/categories/80-glo...anitation-indicators ) which pointed to the importance of treated faeces. At present we have a division between Open Defecation, Unimproved Sanitation and Improved Sanitation. It is possible to have toilets and even improved sanitation but without standards to determine when faeces is treated, it is impossible to say whether any system is really safe.

Sorry Joe, but you are (uncommonly) dribbling with words!
a)

I am talking about any system of dispersed sanitation

You consider any dispersed sanitation system = Ecosan? I am sure you know the difference.
b)
As for the barriers. This depends on the point of view. The first two are for me the most important barriers in terms of sanitation, as they bring the fecal matter to a level where it is MUCH less dangerous as for instance fecal sludge. Than you come to the emptying. I hope you agree that cleaning out a UDDT (with gloves and mouth protection) is WAY more secure than pumping out a fecal sludge tank with handpumps or manual cleaning of pits (even with protection). Therefore the second barrier had large influence.
And for the final destination....I am totally with you (and I think that is the point where we really have the same view) that a centralized collection system would be the best way to go.

c)
There you write about vermicomposting - from my knowledge (i guess we already discussed that somewhere) vermicomposting does not have any influence on the pathogen aspect.

So please indicate better what is the point which makes you so upset.
Is it the lack of centralized systems for ANY sanitation ...most of us feel with you although this for me has nothing to do with Ecosan or sustainable sanitation. You can do a centralized system wasting a lot of energy and other resources and therefore not complying with criteria of sustainability nor ecological aspects but having a safe sanitation system.

I like this discussion as it points to some basic conflicts which still exist (although I did not expect them from your side)

Yours
Christoph

Christoph, I am talking about any system of dispersed sanitation whereby users collect, treat and handle their own faeces. In my view that includes UDDTs, composting toilets - but not systems such as meso scale [monitored] co-composting sites. Most ecosan systems would fit within that, would you not agree?

In terms of the barriers, your first two points are not additional barriers because that is the normal operation of the UDDT. Research from South Africa suggests that normally operated UDDTs do not reduce pathogens to safe levels. In my view this is because it is impossible to tell if stored faeces in a UDDT has been consistently subject to the drying effect and therefore pathogens persist.

The use of safety equipment is a barrier to at-risk workers emptying the UDDTs however they are not always available or foolproof. Also this is not a barrier to other at-risk groups. But yes, risk is reduced if safety equipment is used.

Again placement of the treated faeces can be a barrier, but this depends on consistent practice and knowledge of risky behaviours.

I think these are pretty poor barriers to infection risk from faeces where it is unknown how well pathogens have been destroyed and depend on correct use and behaviour by everyone all of the time.

I do not know about other systems, I assume the problem with a lack of safety standards is the same.

That said it seems to me that it is much more likely that processes can be developed in meso scale composting, vermiculture and other systems with some monitoring to reduce risk to acceptable levels than small dispersed unmonitored systems.

Joe I´m with you on many aspects of not beeing safe for reuse but as Florian pointed out ...for many here that is not the main focus .....and for me the ECOSAN = UDDT discussion is of the past decade.

in most ecosan systems

But you always want us to be precise and now you begin with a sentence like the above.
Could you define ecosan systems better? I have the impression you mean UDDT.

If you ask for the multiple barriers of UDDT, my view is as followes:

• the feces fall into a separated chamber (barrier one)
• they stay there until dried out to a good level which makes handling easy (second barrier)
• the cleaning out should be done with mask and gloves (third barrier)
• and burying with a cover of 30 cm should be done (fourth barrier)

Is this less save than a treatment lagoon which delivers without disinfection (most do not comply with fecal coliforms criteria - but yes normally for helminth eggs)

Yours
Christoph

I would also say that the multiple barrier system is a good one, but what barriers exist in most ecosan systems?

I am not suggesting that the risk should be 0 and the studies I have pointed out do not work on that basis. In fact the way to assess systems microbiologically is using Quantative Microbiological Risk Assessment (QMRA) which is based on acceptable dose rates, which is calculated by the socially acceptable number of infections in a community.

Therefore talking about a risk of zero is not only impossible but not the point I am making - which is that the sector needs acceptable standards so that it is possible to tell when faeces is treated and when it is not and when the risks of handling and spreading are acceptable. Again, studies which use the best information and are based on QMRA suggest that UDDT and composting toilets do not reliably kill pathogens to safe levels.

In Europe the calculation is totally different due to the standards of healthcare available and the lack of endemic faecal diseases.

Good you join the discussion!

joeturner wrote: Advocates of 'humanure' insist that composting toilets kill pathogens when they cannot possibly do so.

You're right that most on-site sanitation technologies do not reduce pathogens to 0. But you are fighting windmills in insisting that everybody here thinks othererwise.

I think "advocates of 'humanure'" usually rather say that different on-site technologies reduce pathogens to very low levels, so that with some additional measures (multi-barrier concept!) the materiales can be safely reused (or disposed off safely).

Let me give you another example: I assume you live in Europe. So you are useing a sanitation system, whose treatment in most cases does not bring down pathogen levels to 0. Most modern wastewater treatment plants in Europe have no disinfection and thus a much lower pathogen removel rate as, for instance, a good UDDT toilet. But that's not a problem at all, as there are good other saftey measures in place.

I think the important part is that ecosan implies dispersed systems without any form of testing

Properly controling individual sanitation systems is indeed a challenge. But again, in Europe or the US, there are very good systems in place to manage dispersed individual sanitation systems. So it is possible to do this safely.

On the other hand, in many countries where monitoring and management of dispersed system is bad, because of weak capacities of administrations there, the very same happens also with centralised sanitation systems.

So if sanitation systems are safe or not, is not a questions of centralised vs dispersed, or ecosan vs. something else. The question is how to make things work.

Note by moderator (EvM): to make it easier to follow, I have separated out the following 13 posts from their original thread which was a discussion on the definition of ecosan:
forum.susana.org/forum/categories/39-any...it=12&start=12#10039
The multiple barrier concept to safe reuse was mentioned in that thread and led to the discussion below.


++++++++++++

I think the important part is that ecosan implies dispersed systems without any form of testing, which is then encouraged to be used in agriculture. Advocates of 'humanure' insist that composting toilets kill pathogens when they cannot possibly do so.

There are good quality studies which show the faeces from UDDTs and composting toilets are not safe to handle and use in this way because they do not kill sufficient pathogens.

Ultimately I don't think you can claim systems are safe if they are not being tested regularly.

It seems to me that few actually want to discuss the microbiological safety of their in-situ systems and the risks involved with telling people to reuse their own faeces.

I have collected a few studies which have considered the microbial safety of ecosan systems on my blog sanitation.joetnr.net/ecosan