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

  • geoffbhill
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Which composting toilet to choose - recommendations, please?

Composting toilets do not make compost. Do not be fooled by the advertisements. My peer reviewed papers on available on this topic. Additional ones can be found in the literature.

There are mixed waste dry toilets (waterless) and urine diverting dry toilets (also waterless). Neither make compost. The definition of compost is a material that has been thermophilically and mesophilically treated to reduce pathogens by 4 logs. Neither mixed waste nor urine diverting dry toilets achieve this without additional efforts. Both can be batch mixed with proper amendments at the right scale (>1 ton) to make thermophilic composting happen. Stabilized urine diverted dry waste (by means of invertebrates or other biological means) can be post treated with urea and ash. Research work by Nordin on this topic.

Waterless toilets are an important aspect of human waste management all over the world, but we all need to be clear on what is false advertising and what is the true value. Composting toilets do not make compost. They do provide a receptable which collects pee and poo (mixed waste) or just poo (urine diverting). Mixed waste toilets have excessively high ammonia in the sludge, regardless of bulking agent. Urine diverted solid waste can be consumed by invertebrates (which are sensitive to ammonia levels).

www.researchgate.net/publication/2357166...zing_the_end-product

www.semanticscholar.org/paper/Vermicompo...9b5e47bbc87e142e3294

www.researchgate.net/publication/2603908...Helminthic_Parasites

Definition of compost per USCC
wasteadvantagemag.com/uscc-efforts-resul...by-regulators-group/
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  • Benno
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Re: Which composting toilet to choose - recommendations, please?

You did not mention the use to which you will be putting the composting toilet. The options will vary depending on number of users, location, and building design. Also availability of a safe and dedicated space for the secondary composting if you use any of the units you listed.

I agree with Geoff Hill that the smaller composting toilets are misnamed and it is misleading to call them composting toilets. One can argue that they do facilitate composting because they make the resources available rather than flushing, burying, or incinerating them, but you would need to physically transport your contributions to a sequestering bin or dedicated compost pile. Depending on number of users, this can become a tedious and unpleasant task. My experiences allow me to disagree with him about in-vessel composting though.

There are other larger, but more expensive options that successfully compost in-vessel, but require a space for a larger container in a basement or equivalent space below the bathroom. Phoenix Composting Toilets are the system I prefer. www.compostingtoilet.com Clivus Multrum, Sun Mar Centrex, are others. The Full Circle Composting Toilet is a UD batch toilet similar to the Separett but with a larger below-floor interchangeable containment vessel.

One thing to keep in mind is that the smaller the toilet and the lower the price will be inversely proportional to the amount of maintenance required for successful operation of the unit. Also, the more direct and intimate contact you will have with its contents. Batch systems such as Separett or Full Circle, require some maintenance, but it is much less objectionable than the potential for carrying open containers of sewage.

The larger “below-floor” systems have a much longer retention time in vessel. Systems like Phoenix, for example, have a multiple year retention time and assure that any material removed is the oldest. I disagree with Geoff that composting cannot take place in-vessel.

Some of the “same-floor”models require that you use a proprietary aka expensive “composting” formula to add to your contributions. This adds an ongoing cost which is not insignificant, when added to the cost of the electrical use for fans and heaters.

Of the ones on your list, I urge you to consider the Separett.
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  • geoffbhill
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Re: Which composting toilet to choose - recommendations, please?

During my Phd on the topic of waterless human waste management at the University of British Columbia (Vancouver BC) I studied for 3 years on composting toilet performance. I sampled waste from dozens of conventional (mixed waste + wood bulking agent) composting toilet units of all manufacturers in North America, including Phoenix, Sun Mar, Clivus, and others. ZERO of them produced anything that resembled compost or fit the definition of compost. Some of the units were installed in fully insulated and heated buildings like the CKChoi building, which was operated by trained and dedicated personnel. Material was too wet, not stabilized, had high ammonia, brewed pathogens, and looked and smelled like raw waste.

The peer reviewed paper is published in Journal of Environmental Management.
www.ncbi.nlm.nih.gov/pubmed/23435183

If anyone has data to show that a composting toilet makes compost, I'd be excited to see it and review it. Here is the data that is necessary to prove that a composting toilet makes compost
1: needs to have a documented thermophilic step to kill pathogens (temp sensor record) along with indicator testing (E.coli). In the absence of a proven pathogen reduction step such as temperature, the material would need to be tested for the full suite of potential pathogens including hook worm ova viability, enteric viruses, as well as the usual E.coli. E.coli testing on its own, in the absence of temperature monitoring shows very little in the way of true pathogen risk.
2: needs to be well stabilized (i.e. high Solvita value like >5 or such)
3: needs to have a low ammonia value and some nitrate should be found in the material
4: should not have offensive odors
5: should not have big turd looking shapes in it

In order to make compost there needs to be a thermophilic stage. Never in documented literature has a composting toilet (box below a poop hole) has a toilet waste pile been found to achieve thermophilic temperatures (or really anything greater than 10C over ambient). Moreover, there are a half dozen other biochemical and design reasons why these units will never make compost including: A) short circuiting due to leachate seeping through fresh turds on the top of the pile into the bottom 'finished' zone within a few hours; B ) excess ammonia from urination preventing biological activity (the ammonia levels in most 'composting' toilets was so high that it killed nearly all life, and was almost a viable pathogen destruction method - I joking called these toilets 'toxification toilets' instead of composting toilets).

Lets not propagate inappropriate terminology. Composting toilets don't make compost. Lets call them waterless toilets or dry toilets. Compost is a special term for a material that is safe, stable, and beneficial. The material that emerges from composting toilet chambers below poo holes does not (and I daresay cannot) produce material that meets these important safety concerns.

If we continue to call composting toilets "composting toilets" we do so in the face of science at the continued risk of human health impacts due to the perception that the end-product is actually compost, a safe, stable, and beneficial substance.

We should be focusing on reclaiming nutrients from diverted urine, which self sanitize in batch storage, have 10x the nutrient value by weight compared to feces, no heavy metals, and flows by gravity. Urine diverted feces can be fed to bugs, minimized, rarely touched by humans, and post-treated with urea and or ash, for final pathogen destruction of the well stabilized 10+ year old material, prior to trash removal (screening) and subsequent land application.

Following this ethos, ToiletTech has implemented 200+ urine diverting toilet solutions at some of North America's highest use public back-country sites including Zion's Angels Landing, Whistler Canada, Mt Rainier Washington, Longs Peak Colorado, Smith Rocks State Park Oregon. Our toilets at these sites are visited hundreds to thousands of times per day. Many of these sites had failing composting toilets or evaporating toilets. Our systems reduce the operator costs to 1/5th of the original and result in very small residual waste to be managed / removed / pontificated about. Happy to share references to operators in the National Park, Forest Service, and State Park for those trying to figure out how to manage waste at high use sites.
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  • bowenarrow
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Re: Which composting toilet to choose - recommendations, please?

I would consider this post as advertising, something I would have thought was not permitted on these pages.
Ross

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Comment by moderator (EvM):
Geoff's post is deemed to be acceptable, see also here: forum.susana.org/241-composting-toilets-...let-a-misnomer#27525 and here: forum.susana.org/39-miscellaneous-any-ot...-allow-on-this-forum
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  • KaiMikkel
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Re: Which composting toilet to choose - recommendations, please?

Hear, hear! I've made similar points elsewhere on this forum and have even gone so far as to argue that what most composting (i.e. non-source-separating) toilet manufacturers are engaged in is fraud. I feel like that sector has done more to jeopardize widespread adoption of waterless toilets than perhaps any other factor. I never recommend nor advocate on behalf of non-source separating waterless toilets and feel like we as a sector should speak out more about this flawed technology and its many misrepresentations.

Kai Mikkel Førlie

Founding Member of Water-Wise Vermont (formerly Vermonters Against Toxic Sludge)
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  • geoffbhill
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Re: Which composting toilet to choose - recommendations, please?

Bowen

Toilet Tech's markets are in North America. Prior to starting this toilet business I studied composting toilets. To such a level that UBC had to bring in a European examiner to examine my thesis, as by the end of my 4 years, I had dug deeper into this shiz pile (thick with green-washing) that any other professor or researcher in North America. My PhD findings exist without bias in the publications I have provided. I spoke of the content with these.

What is missing in these forums are the voices of people & agencies actually operating these units. There are lots of voices of consultants and distributors but little opportunity for prospective buyers / users / mission critical agencies like WHO to talk to the actual people who maintain these waterless toilets day in and day out.

I am providing the opportunity for anyone to speak directly to individuals within US and Canada public agencies who operate a variety of mixed waste composting toilets, pit toilets, urine diverting dry toilets so that they can go straight to the source, avoiding the sales pitches.

Censor these postings and we go back to the greenwashing of 'compsoting' toilets.

Geoff
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  • bowenarrow
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Re: Which composting toilet to choose - recommendations, please?

This is a global site. Experience in North America will be different to experience in the southern hemisphere and just because of bad experience in North America is no reason to say that ALL systems don't work.
I work in the field here in Australia not as an academic but as a designer and builder with over 30 years experience. I could not have survived if my experience was the same as outlined, although I quickly learned at the beginning that urine has no place in the mix, and is a valuable resource being wasted.
Change the terminology if you wish but leave advertising out.
Ross
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  • geoffbhill
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Re: Which composting toilet to choose - recommendations, please?

My literature review in my Phd was English speaking and publishing countries. Poo, pee, and the biochemistry of their bio-oxidation doesn't change dramatically with latitude or longitude. Ambient temperature changes a bit, but doesn't help it get thermophilic.

All I am advocating for is a change in terminology, yes! Composting toilets don't make compost. But there are many reasons to still design, build, and maintain waterless toilets. Just forget the dream that they make compost (definition of compost is: safe, stable, mature).

It is possible to make compost by further handling the waste from within a box below a toilet seat (often called a composting toilet).

Geoff
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  • cecile
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Re: Which composting toilet to choose - recommendations, please?

Dear Geoff,

Thank your for your feed back. I have seen what you are advocating for - further handling of waste from toilets - in the Philippines by the organisation WAND foundation. They used to collect dehydrated faeces from UD toilets and co-compost it with organic waste and earth worm.

I am quite aware of the UD toilets you have been installing, which are separation toilets followed by vermi-composting. When I was working for the manufacturer we sent the "compost" to the lab and the results were very good, and they even complied with French standards for compost.

What are your findings in terms of compost quality for the toilets you have been installing in the US and in Canada? How are the output products of the toilets used?

Best regards,

Cécile Laborderie
MAKATI Environnement
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  • HarryTams
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Re: Which composting toilet to choose - recommendations, please?

Kai
Can you explain what you mean by "non - source - separating"?
Harry
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  • HarryTams
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Re: Which composting toilet to choose - recommendations, please?

Re: "All I am advocating for is a change in terminology, yes! Composting toilets don't make compost. But there are many reasons to still design, build, and maintain waterless toilets. Just forget the dream that they make compost (definition of compost is: safe, stable, mature)."
I have been working together with University of Tasmania (Architecture and Design) to develop transportable and autonomous 1-2 person micro-dwellings (for young people) to be deployed on the same site as a family home. Waterless toilets have been utilized in few of the dwellings by customers who have decided not to seek official approval from building, planning, and /or health authorities.
Customers requiring official approval have needed to deploy the dwellings where there is access to the sewer system and all have used water flush toilets. That takes the transportability and autonominity away
I sincerely believe that the aim of waterless toilets needs to be SAFE. Urine diverting dehydrating toilets (UDDT) would be accepted by most governing authorities if the fecal material was free from pathogens. Pathogen free product from the chamber below the toilet seat could the be discarded, composted, or utilized in any manner desired by the user. Could this be be achieved by heat alone?
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  • geoffbhill
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Re: Which composting toilet to choose - recommendations, please?

Hi Elisabeth

Thanks for your input and feedback. Glad I didn't violate any forum rules. *

I do think we can change the term composting toilet to waterless toilet or dry toilet. And I think there are a number of really good reasons to change the name, all of them center around human health and preventing confusion around what is safe and what is not.

Lets first start by clarifying the definition of Compost (and thus Composting as a process to produce Compost). One of the most reputable sources on this comes from the USCC (US Compost Council). I've put the definition below starting with "Definition of Compost". In essence, composting (to make compost) requires a thermophilic step. This high temp step is the pathogen killing step. This is one of they critical aspects of composting that makes compost safe, especially when feedstocks are human waste from developing world where Ascaris ova are common and in high density in feces. Without the high temperature step, destruction of Ascaris and other pathogens is very slow (maybe years if a batch is isolated from the rest of the waste pile).

The average composting toilet has people pee and poo into a hole and add bulking after they 'go'. These are generally operated as a continuous system of one sort or another (top to bottom Phoenix, back to front Clivus etc). This mess of poorly mixed ingredients has never been documented, in the recorded English literature, to achieve thermophilic conditions. Even if 1x10^6 stars aligned and it hit 55C for a day, the system is continuous flow, so more raw waste is added to the top, and seeps down through the whole mass re-contaminating it. There are many biological and thermodynamic reasons why sporadic pee and poo and bulking agent tossed into a dark hole doesn't conspire to make the right mix and self-heat to >55C continuously (all of these are stated in my publications on this topic) 1) way too much available N and way too little biologically available carbon resulting in high ammonia levels (toxic to beneficial bacteria and all invertebrates) 2) too much water from pee (people pee more than they poo in a day) 3) rate of heat loss many times greater than rate of heat generation.

For urine diverting toilets, invertebrates are not able to destroy or make in-viable the eggs of hookworm. I did another paper on this topic. This low temperature invertebrate driven process results in highly degraded material, well stabilized and mature (high nitrate) but does not have a sanitization step that is reliable for human safety.

The wikipedia article about proper bulking agent, C/N, moisture, density, mixing, and all those things is important when making a batch mix of organic materials for composting (with a shovel or mixer and the various ingredients at hand), at a scale >1m^3 (and all the way up to 1000 m^3 batches), and if these aren't achieved, this batch probably won't self heat to thermophilic conditions either. The reality is that these conditions never occur, under a toilet hole, consistently enough to generate a product that can pass as compost.

SUMMARY
The term Composting and Compost imbues safety. Indeed, core to the definition of compost is a process which makes it safe. This process NEVER happens within a composting toilet. All my studies, reading, and experience show that this thermophilic process can ONLY happen after the waste is removed, is mixed properly, and thermophilic temperatures are achieved and monitored, and only with these, can we imagine making compost from toilet waste. --- For stabilized vermicompost, its possible to add urea and ash as a final sanitizaiton step... see work by Nordin.

Why would we keep the term "COMPOSTING" in front of "toilet" when they don't achieve the key principles within the definition of "COMPOST"? Doesn't this propagate confusion and elevate the risk that people will use the end-product from composting toilets as if it were already COMPOST?

Geoff


Definition of Compost: The term “Compost Product(s)” shall include EITHER of the following two numbered items: (summarized here in this publication: wasteadvantagemag.com/uscc-efforts-resul...by-regulators-group/ )

COMPOST

1) An item, material or finished article sold in commerce that meets ALL of the following criteria:

a. Is the product manufactured through the controlled aerobic, biological decomposition of biodegradable materials

b. Has undergone mesophilic and thermophilic temperatures, which significantly reduces the viability of pathogens and weed seeds, and stabilizes the carbon such that it is beneficial to plant growth

c. Is typically used as a soil amendment, but may also contribute plant nutrients

d. Bears little physical resemblance to the raw material from which it originated

e. Is an organic matter source that has the unique ability to improve the chemical, physical, and biological characteristics of soils or growing media

f. The sanitization through the generation of thermophilic heat shall meet the standards of the Processes to Further Reduce Pathogens (PFRP), as defined by the Code of Federal Regulations Title 40, Part 503, Appendix B, Section B.

2) Vermicompost/worm castings (worm manure) for which all feedstocks have been composted prior to their being fed to the worms AND which meets PFRP (Processes to Further Reduce Pathogens).


++++++++++
* Comment by moderator:

This was the response by Elisabeth to Ross on 27 May (her post has since been moved out of this thread, therefore text is copied below)

Hi Ross,
You wrote yesterday "I would consider this post as advertising, something I would have thought was not permitted on these pages."

Please clarify to me which post or which statements exactly you disagree with? I couldn't find anything objectionable in the posts above your post. To me this seems like a useful discussion about various aspects of composting toilets, including the definition of the term "composting toilet".

With regards to advertising: you are right we don't allow plain commercial advertising. But we are flexibel when it comes to discussing available projects and services.
You can find this here under Rule 10:

We do not allow plain commercial advertising. On the other hand, we do encourage private sector participation and therefore are open to posts by people working for companies selling sanitation related products and services. A technically sound introduction of sanitation-related products and services is in principle allowed in this category. For example: A user who provides helpful advice and interesting information to other forum members on composting toilets, is allowed to explain their own company’s composting toilet products and to engage with other users on discussions thereof. In other words: SuSanA members can share information about products and services related to sanitation on the SuSanA Forum, as long as it is part of a productive dialogue with other SuSanA members.


Many private sector people (like yourself) have stuck to that rule and have made interesting and meaningful contributions to this forum. So I would say the "no advertising" rule ought to be applied with caution as not all advertising is the same. Geoff's posts above are fine by me.

See also separate post about the question of advertising here: forum.susana.org/39-miscellaneous-any-ot...-allow-on-this-forum
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