Composting toilets do not produce compost - true or false? And is "composting toilet" a misnomer?

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  • Boyercutty
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  • Owner builder, three houses as far. Owner of a waterless toilet. Current interest and reason for joining Susana.org is in large scale Clivus Multrum systems. Currently living in Timor Leste, a country badly in need of thousands of toilets and safe disposal of end products.
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Re: [SuSanA Forum] Composting toilets do not produce compost - true or false? And is "composting toilet" a misnomer? (Composting toilets, Arborloos)

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.
Keith CJ Schekkerman
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  • KaiMikkel
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Re: [SuSanA Forum] Composting toilets do not produce compost - true or false? And is "composting toilet" a misnomer? (Composting toilets, Arborloos)

I found the following, which arrived earlier today in my inbox, particularly instructive/insightful:

oaec.org/first-compost-toilet-research-samples/

Here's a highly motivated group of people with all kinds of resources available to them and, still, they run into all kinds of problems with a mass-produced (so-called) "composting toilet". If these folks encounter the problems they did, just imagine what the general public goes through when trying to manage a non-source separating waterless ecological toilet.
Kai Mikkel Førlie

Founding Member of Water-Wise Vermont (formerly Vermonters Against Toxic Sludge)
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  • bowenarrow
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Re: [SuSanA Forum] Composting toilets do not produce compost - true or false? And is "composting toilet" a misnomer? (Composting toilets, Arborloos)

My reading of this is that these are minor problems, bureaucratic and the like, and the real tests will be the results in a few years time. We must remember that the alternative to "composting" toilets is the flush toilet and these, whilst being mainstream, are no real answer. You never see the results of tests by municipal authorities (if any) of the "quality" of what is dumped into our Oceans, forgetting the ever increasing value of water used to flush.
I am encouraged by this report.
Ross
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  • geoffbhill
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  • Dr. Hill Waterless human waste researcher Toilet Tech director Engineered Compost Systems director
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Re: [SuSanA Forum] Composting toilets do not produce compost - true or false? And is "composting toilet" a misnomer? (Composting toilets, Arborloos)

The 'samples' were of wood shavings as they said in their post and can be seen in the bags. Correct me if I'm wrong here.

Looks like the unit can take 1-2 cubic yards of wood shavings and sawdust (similar to other color compost toilet chamber brands), which is usually shipped dry (light weight). Lets assume there is 500kg of dry wood product as a starter. Moisture is 30%. It can absorb up to 70% moisture before it hits its saturation point and starts letting black water down. So the plug of wood could hold an input of about 550kg of water (urine) before it started leaching. At a generation rate of 0.2l urine per user, this is around 3000 uses to load the system to its saturation point. How many users use the toilet per year currently? Once at the saturation point, the material will change in character. After the 1-2 cubic yards of saturated wood shavings are removed, then you get down to the feces mixed with saturated wood (urine saturated) and this this is the third phase of the toilet (finally in full operation). This can take many years at low use sites. Then this is the 'compost' which I sampled in the 10-12 units throughout North America in 2010-2012; all samples were wet (urine), very high ammonia, high E.coli, looked like turds coated in wood shavings. If people don't use the toilets to pee, and pee on trees instead, and don't use that much woody stuff, the system would work much better (less waste mass and better decomposition). For sites used heavily for urination there is an excessive need to add bulking agent to soak up the water lest it just become a soupy mess, but this does not resolve the excessive nitrogen issue, and the biochemical pathway results in ammonia generation which is pretty much toxic to the mesophilic decomposer organisms (bugs or otherwise) that would consume the feces and wood. The nitrogen is all highly available but the carbon in a chunk of wood is not very 'available' or interesting and does not get used well in mesophilic temperatures.

Excerpt:
"For the real eco-sanitation geeks, you may be interested to know that these first samples were taken from what could be called the “starter” or “pre” batch – the chambers were initially filled with wood chips and shavings to provide a base of carbon material upon which to build the compost. This is to say that the test results for this first round may not be representative of what future batches will look like because these will likely contain a much higher ratio of total carbon."
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  • joeturner
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Re: [SuSanA Forum] Composting toilets do not produce compost - true or false? And is "composting toilet" a misnomer? (Composting toilets, Arborloos)

As geoff says, much of the carbon in wood chips are in lignin which takes a long time to breakdown, and is resistant to the microbes you actually want to be growing in faecal compost. Also if it is chips, the surface area is low. It would be better, but probably still not great, to use sawdust.

It still puzzles me why anyone could possibly imagine that this could sanitise anything. In the worst scenario, it might actually incubate/increase the worst pathogen loads.

Faecal composting needs a lot of air, a lot of easy carbon and low nitrogen. Why hasn't this simple formula and basic microbiology become widely understood?
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  • AndyWarren
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  • I'm the Managing Director of NatSol Ltd, Composting and Remote Toilet Specialists. We operate almost exclusively in the UK and design and manufacture our own products. These are supplied to sites such as allotments, rural churches, public parks and campsites.
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Re: [SuSanA Forum] Composting toilets do not produce compost - true or false? And is "composting toilet" a misnomer? (Composting toilets, Arborloos)

Geoff is certainly right about the lignin in wood. We have often recommended Hemcore (or similar - that's a proprietory name) which comes from industrial hemp and breaks down more easily. However, it's not so easily available. If wood is to be used we recommend shavings as these create more air spaces in the pile and it is far less likely to become anaerobic. We know that from experience. We urine separate of course.
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  • AjitSeshadri
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  • Marine Chief Engineer by profession (1971- present) and at present Senior Faculty in Marine Engg. Deptt. Vels University, Chennai, India. Also proficient in giving Environmental solutions, Prof. Ajit Seshadri, Environment Consultant located at Chennai, India
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Re: [SuSanA Forum] Composting toilets do not produce compost - true or false? And is "composting toilet" a misnomer? (Composting toilets, Arborloos)

Dear Andy Warren.
Its hard to bio degrade FS, we have seen that co composting with veg market waste and some agri waste helps.
After initial anaerobic process in coverd pits for 1- 2 weeks, have vermi process composting in open pits, Worms shifting to newer and fresh matter within pit, would reveal that the bio matter is getting to be totally composted in 2- 3 weeks . Then the bio -matter is removed for drying and for packaged ready for use.
Worms when exposed to open areas gets worms seekers pilfer the stock and some take away worms for use as fish- bait.
This process is hardy but realises good compost, nutrient, N P K and minerals rich .. well wshes ..
Prof. Ajit Seshadri, Senior Faculty in Marine Engg. Deptt. Vels University, and
Environment Consultant (Water shed Mngmnt, WWT, WASH, others) Chennai, India
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  • AndyWarren
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  • I'm the Managing Director of NatSol Ltd, Composting and Remote Toilet Specialists. We operate almost exclusively in the UK and design and manufacture our own products. These are supplied to sites such as allotments, rural churches, public parks and campsites.
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Re: [SuSanA Forum] Composting toilets do not produce compost - true or false? And is "composting toilet" a misnomer? (Composting toilets, Arborloos)

Hi Ajit,

Thanks. - though didn't understand 'FS'.

We have always advised people not to put veg waste in toilets as it attracts fruit flies (Drosophila). However, out toilets are almost all in temperate regions and have long slow decomposition cycles. If the composting cycle is shorter perhaps that's not an issue.

Andy
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  • joeturner
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Re: [SuSanA Forum] Composting toilets do not produce compost - true or false? And is "composting toilet" a misnomer? (Composting toilets, Arborloos)

FS is presumably faecal sludge. We don't tend to use the word "sludge" around here as in industrial countries it might imply a mix of industrial and household wastewater solids.

Long slow decomposition does not kill pathogens.

It may be enough in countries where pathogen incidence is low and where other barriers exist.

As has been well known for at least 40 years, faeces compost needs to reach a high temperature for a minimum period. Most experts think this needs to be at least 50 degrees c. Some think that it should be much higher and for a longer period.

All agree that sanitation only occurs of the entire contents of the co-composting reach that temperature.

It is highly unlikely that a slow unmonitored temperate composting system in temperate regions would ever reach those kinds of temperature. Hence I cannot see that the contents could ever be described as fully sanitised to any international standard.


Edit: it is quite frustrating that these obvious, well known facts need repeating multiple times.
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  • BrianReed
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  • A trainer in WASH with over 20 years experience of capacity building globally.
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Re: [SuSanA Forum] Composting toilets do not produce compost - true or false? And is "composting toilet" a misnomer? (Composting toilets, Arborloos)

If you want a core text on excreta and health, have a look at

documents.worldbank.org/curated/en/70404...astewater-management

it has charts showing the pattern of pathogen die -off related to temperature and time (i.e. pathogens take a longer time to die off under lower temperatures).

I did read the question in a different way however. I am a gardener as well as a WASH trainer, so I focused on the word "compost". Yes the other posts did mention the need for a good C:N ratio (or brown/ green mix as gardeners might see it) to get a good result. My attention however was on the use that this compost might be put to. The NPK ratios of composted faeces are not great from a fertiliser perspective - it's the urine that has the nutrients. Well composted faecal matter might be fine as a soil improver - but composted green waste is also very good and without the health concerns. There is also the issue of harvesting / dormant seasons and the storage of urine especially. So are you seeing compost as a way of disposing of excreta or a positive contribution to soil health? Personally I use urine as a compost activator mixed with garden and vegetable waste - and the pathogen rich faecal matter goes down the sewer. It can depend on what your perspective is.

I have come across reports of composting latrines being used, but the "product" just being dumped as transport/ fertility/ yuk factor was against its use. The people were using the toilets however as they were designed to be emptied easily so made maintenance cheaper.

hope this is helpful!

Brian Reed
Brian Reed
BSc (Hons)(Dunelm), PGDip (Lond), MSc (N’cle), CEng, CEnv, C.WEM, MICE, MCIWEM, FHEA
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  • AndyWarren
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  • I'm the Managing Director of NatSol Ltd, Composting and Remote Toilet Specialists. We operate almost exclusively in the UK and design and manufacture our own products. These are supplied to sites such as allotments, rural churches, public parks and campsites.
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Re: [SuSanA Forum] Composting toilets do not produce compost - true or false? And is "composting toilet" a misnomer? (Composting toilets, Arborloos)

Thanks for the link to the Richard Feachem document 'Sanitation and Disease'. That's my bed time reading sorted for 6 months.

I too use urine from my own urine separating toilets as a plant food, and in composting of high carbon/low nitrogen waste material e.g. cardboard. We had a client who wanted us to install a collection tank for urine from a toilet we supplied so that they could do the same. But they are Soil Association registered and the SA don't allow that, so it got dropped.
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  • vijuhegde
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Re: [SuSanA Forum] Composting toilets do not produce compost - true or false? And is "composting toilet" a misnomer? (Composting toilets, Arborloos)

Hi, I have friends who use a compost toilet and yes, it produces compost. It's a dry toilet.
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