Greetings all,
As a very recent subscriber to SuSanA, I invite people who are taking part in this interesting discussion to comment on sketch plans for a Clivus Multrum type of toilet. With very dodgy internet and few resources Timor Leste is not an easy place to work from.

My thread is at , forum.susana.org/241-composting-toilets-...ion-from-timor-leste

With lots of building experience but little in the finer design points of dry toilets, your input is of great value to me.
Cheers Keith Schekkerman, Timor Leste, Baucau.

I/we (NatSol) have always assumed that thermophilic composting was less reliable than long term mouldering because of the difficulty of ensuring all parts of a pile get to temperature – unless, of course, a more industrial approach is used. However, I fully accept that long term mouldering will not deal with helminths.

Ok maybe he's changed his tune. It was a while back I read his book in fairness.

Anyway, it doesn't really matter - he still apparently advocates a basically random addition method with no monitoring. Without having a good idea of the C:N ratio and without proper monitoring of oxygen levels and without a programme of regular turning, it is still guessing.

Which still isn't a way to do faecal composting. It is still to advocate magic.

I read one of Joe's first books and he describes failures within "composting toilets" (as in boxes under toilets that were magically supposed to hit the key criteria for thermophilic composting). I didn't know he moved towards support of the magic reactor black box. My biz partner spoke to him at one point, and he was very much more about making a good mix of stuff with a shovel before 'composting' efforts were applied.

Geoff

To get hot composting temperatures, the C:N ratio must be within specific values and there must be sufficient oxygen to allow the thermophilic microbes to grow.

Even if sufficiently high temperatures are achieved within part of a heap or windrow (usually easily achievable in the top-middle), the challenge is to ensure that all of the faeces has reached temperature.

So with the high amounts of carbon, sufficient oxygen and the necessity to turn the material, it is impossible to imagine anyone doing this reliably without any monitoring equipment. Any material produced in this way would need microbial testing to show it was safe. I highly doubt it would be.

It is beyond imagination to think it could be done in a space below a toilet without any oxygen or proper accounting of carbon and nitrogen.

The only part I disagree with Geoff is the idea that Jenkins talks about secondary treatment. In fact he goes to great lengths to try to prove that collecting faeces in buckets with chippings will compost into safe material.

Anyway, I have no interest in further discussing Jenkins or his misguided ideas.

I agree fully with Joe.

Urine diversion toilets are not so high on their horse to imagine poop doing much other than drying a bit in a UD DT. This is why most don't pretend with a facade of 'composting' in front of their name.

We are debating about the definition of compost again. It has been defined in the USA as something that is safe, stable, having been through thermophilic temperatures, with monitoring. Boxes under toilet hole will never achieve this.

Composting toilets are a misnomer.

Composting mixed human waste, after, separately, is Joe Jenkins style, and can be done well. This is the composting of human waste.

Vermicomposting does not destroy hook worm ova or render them in-viable.
www.researchgate.net/publication/2557338...micomposting_toilets
Other paper attached here for non commercial means.

Verimicomposting does not make compost. No high temperature step.


Geoff

Well they are systems which collect material below toilets in a confined space with regular additions of carbon rich material. Without any temperature or any other kind of monitoring.

That is what most people understand as a "composting toilet".

It is fairly clear from Save's work that the toilets in question are neither "dehydrating" nor "composting".

And it further seems to follow that "ecosan" systems designed in this way are therefore not reliable ways to sanitise faeces, whether they are said to be "dehydrating" or "composting" - functionally it makes no difference.

I feel like I have said it before on this thread - but it is much like making beer or cheese without any understanding of the microbiological and physical systems involved - in spaces where it is plainly impossible and where studies show it cannot work - adding random amounts of ingredients and then imagining that a product will come out the end that is not actually lethal.

Yes - the product needs to be safe. Whatever the system is called and whatever magic is supposed to be happening, if it doesn't produce a safe product it is useless.

We can call it whatever we like, but faeces plus carbon in a confined space beneath a toilet does not make a safe product. Ever.

Thanks, Joe, for your quick response..

I agree that Save Kumwenda's work is very interesting and detailed but it does not relate to composting toilets, but to UDDTs which he sometimes also calls ecosan-toilets. UDDTs are NOT composting toilets as the name says. They are 'de-hydrating' toilets which in my understanding is a different process, or?

I understand 'composting' is the degradation of organic matter at specific temperatures, moisture content and under aerobic conditions.

But maybe 'composting' can also be described by the product which comes out of it where I would not know how to describe it. But then the de-hydrated faeces from an UDDT can eventually be named as 'compost' which is why some people call it a 'compost' toilet?

Therefore I am also not sure whether vermi-digestion can also be called vermi-composting because eventually the resulting humus falls within the material description of compost?

Nevertheless, I think not enough research has been done to evaluate the safety of vermi-composting. We had a discussion in a different thread here about the topic. And in spite of the many research sources quoted by Prof Rajiv Sinha in his two papers, I am not sure about the safety of the humus from vermi-composting.

ciao
Hajo

I personally think it is highly unlikely that unmonitored micro vermicomposting systems reliably destroy pathogens. I believe, having read far too many studies now, that there are no systems at all for unmonitored (primary) below-toilet collection/treatment that are reliable.

The key point here is about reliability. If we can't be sure that an unmonitored system actually destroys pathogens to safe levels then I don't believe it can be described as sustainable sanitation.

The small number of studies which have calculated the risk of infection using known microbiological methods have shown that the chances of catching an infection when handling materials from an unmonitored composting toilet is extremely high. Way beyond what is acceptable in places where few barriers to infection exist.

See Save Kumwenda's work that concluded

"The risk of 5.6× 10−1 means that about 6 out of 10 (60%) people using FAs or UDDTs will be infected by A. lumbricoides during a year or at an individual level; it means that out of ten exposures to sludge 6 times will result in infection. The risk obtained was above the WHO recommendation of between
10−4 and 10−3 infections per year"

forum.susana.org/uddts-for-particular-si...d-latrines-in-malawi

I don't believe there is any significant difference between the toilets in these studies and the general understanding of a "composting toilet" as per wikipedia.

hello Joe,

I agree with you that we have to differentiate between primary and secondary composting... and that 'composting toilets' should be understood as primary composting 'system' where the composting is supposed to take place in a 'vessel/vault' under the toilet.

And you are of the opinion that primary composting under the toilet, producing safe compost, free of pathogens has not yet been achieved. Did you have a look at vermi-composting/-filtration/-culture ?

The worms seem to destroy most pathogens reliably producing a safe and nutritional humus. It is still questionable whether ascaris are also destroyed or only be washed out with the effluent. But at least the humus should be free of pathogens. I express this all with caution as I have not heard of/read a report which confirms one or the other. But maybe you have information about this.

ciao
Hajo

No I was referring to studies looking at systems "composting" materials in vessels below toilets.

The efficiency of secondary composting treatment (where collected material is composted somewhere else) is a whole other issue.

As I said above, I don't believe the majority of people who look at the "Composting toilet" page on Wikipedia are thinking that it means collection and secondary treatment.

There is a mountain of published research about many different secondary faecal composting systems - which, given the right conditions, destroys pathogens reliably.

There are some new studies of material collected beneath toilets - where it is euphemistically described as composting - where pathogens have not been reliably destroyed.

Unfortunately I don't have time at the moment to work on the Wikipedia page, but the papers are not difficult to find.
Secondary faecal composting can work. Primary faecal composting beneath toilets is a misnomer.