Which composting toilet to choose - recommendations, please?

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

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

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.

Hi Geoff,
I am a big fan of getting terminology right. I don't think we can eliminate usage of the term "composting toilet" but we can define what we mean by it. It says "composting toilet", it doesn't say "a toilet that produces perfect, pathogen-free compost". I think the best place to come to an agreement about terms is Wikipedia. Do take a look at the current Wikipedia article on composting toilets. I was involved in improving it. If you would like to suggest improvements to it, please feel free.

This is how the summary currently reads:

A composting toilet is a type of toilet that treats human excreta by a biological process called composting. This process leads to the decomposition of organic matter and turns human excreta into compost. It is carried out by microorganisms (mainly bacteria and fungi) under controlled aerobic conditions.[2] Most composting toilets use no water for flushing and are therefore "dry toilets".

In many composting toilet designs, carbon additives such as sawdust, coconut coir, or peat moss is added after each use. This practice creates air pockets in the human excreta to promote aerobic decomposition. This also improves the carbon-to-nitrogen ratio and reduces potential odor. Most composting toilet systems rely on mesophilic composting. Longer retention time in the composting chamber also facilitates pathogen die-off. The end product can also be moved to a secondary system – usually another composting step – to allow more time for mesophilic composting to further reduce pathogens.

Composting toilets, together with the secondary composting step, produce a humus-like endproduct that can be used to enrich soil if local regulations allow this. Some composting toilets have urine diversion systems in the toilet bowl to collect the urine separately and control excess moisture. A "vermifilter toilet" is a composting toilet with flushing water where earthworms are used to promote decomposition to compost.

Composting toilets do not require a connection to septic tanks or sewer systems unlike flush toilets.[2] Common applications include national parks, remote holiday cottages, ecotourism resorts, off-grid homes and rural areas in developing countries.

en.wikipedia.org/wiki/Composting_toilet

Perhaps we should change the second sentence from "and turns human excreta into compost" to "and turns human excreta into compost-like material which may or many not still include significant amounts of pathogens". Mind you, we are writing to lay persons here so we have to be careful to keep it as simple as possible.

Regards,
Elisabeth

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(Funded via GIZ short term consultancy contract)

Dr. Elisabeth von Muench
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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).
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  • KaiMikkel
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Re: Which composting toilet to choose - recommendations, please?

Harry wrote:

Kai
Can you explain what you mean by "non - source - separating"?
Harry


Certainly. A source separating toilet segregates urine and feces at the source via a split bowl design that directs urine to the front (where it travels to its own area or storage container) and feces towards the back (where it drops straight down into its own chamber or storage container). A non-source-separating dry toilet is one in which urine and feces are deposited into the same container or chamber and thus allowed to mix. As far as I am concerned this represents a major flaw in non-source-separating dry toilet design, at least those mass-produced versions which are sold under the term "composing toilet".

Kai Mikkel Førlie

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

Hi Elisabeth!

I'm with Geoff on this. The term "composting" when used to describe a non-source separating dry toilet is a real problem out there, both in the marketplace and the minds of many people. I know that when I was researching which dry toilet design to go with for our own home I was shocked when all I could find in terms of online user reviews of dry. non-separating container-based toilets was people describing really terrible experiences with these types of toilets. The vast majority of the problem was generated from the misnomer in the name that manufacturers and retailers were using to describe these toilets: "composting toilets". As Geoff and I have pointed out, attaching the word "composting" to these toilets is seriously problematic especially, as Geoff has argued, since none are actually able to achieve the process known as "composting". Instead, they lead to the production of a nasty slurry which, aside from the associated negative odors that occur when urine and feces are allowed to mix and then stew (often times made worse thanks to heat produced by a thermal electric element which is often part of the design of these toilets), causes all kinds of maintenance and other practical problems. As I said earlier, the damage to our sector that these toilets have done (at least in North America) is immeasurable and immense. In this regard, I absolutely think that SUSANA and others should make a major effort to banish the phrase "composting toilet" from the world's sanitation lexicon. How this phrase has been allowed to exist this long is beyond me. It's false advertising of the worst sort.

Kai Mikkel Førlie

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

The commercial product "compost" should certainly undergo pfrp, but sanitisation of compost I produce at home and do not dig into my food garden is not necessary. Just like my non-thermophilic compost heap out the back of the garden, the dark toilet hole produces compost. It is not sanitised compost, my garden compost heap is full of weed seeds and the toilet compost is full of ascaris, but the US Compost Council can't tell me it isn't compost. They have standards for their producers who sell the stuff and the product itself, but not the equipment used for making it and not something I make myself for myself.

Certainly I should be aware that the compost from my composted mess of poorly mixed ingredients in my dark toilet hole is not safe to use in food production, but is it a vector of pathogens and unsafe if I put it around my fruit trees? Nope. Because I'm not selling the stuff it is still compost, I just need to be aware it is not sanitised compost. Of course, if my dark hole does not provide the necessary conditions for decomposition to take place, I am not making compost at all and my toilet is not "composting". 

Dean Satchell, M For. Sc.
Go-Eco Sustainable Solutions
www.go-eco.co.nz
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  • bowenarrow
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Re: Which composting toilet to choose - recommendations, please?

My view on this subject is that by all means create a new title but lets not forget that people out there who want to do their bit by having sustainability in mind do not want to go shopping for a toilet that has a lengthy, if academically correct, title. Basic marketing.
Also in my experience the only toilets I have ever come across in my 30 odd years of being around the Industry that have given problems are single bowl toilets where the urine is mixed and not handled separately, hence the slurry. Perhaps Urine Diverting Toilets should be the only type approved. I do not approve of the term UDDT as any Urine Diverting toilet uses water for cleaning and there is moisture from other directions as well.
I sell 2 different Pedestals for the Industry along with my own continuous system, and these Pedestals are sold as Waterless or Composting depending on the users plan. I have never had anything other positive comments about both, but I have not had any scientific examination just personal examination of the resultant "humus". No doubt if I put them to a laboratory test you would find something but nothing more than the by products of a conventional flushing sewer system.
Ross
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  • arno
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Re: Which composting toilet to choose - recommendations, please?

My take on this is that the term "composting toilet" is a misnomer from a technical/scientific point of view. Mixing urine and faeces and storing it in a container I agree makes for a primitive toilet creating major odour problems indoors and outdoors near the vent outlet. I think most people that have installed a "compost toilet" and have experienced the odour and maintenance problems, will sooner or later get rid of it never to buy a dry toilet again. But for some reason there are some stubborn manufacturers that insist their product to be superior to UDDTs. Ignorance among buyers has kept the "composting" toilets around even to this day.

I do, however, have good things to say about the Clivus multrum, especially when it comes to choosing an ecosan public toilet. This is really the only toilet that can produce its own compost - but this requires additions of carbon sources, soil bacteria and a large enough understory container such that a composting ecosystem can develop. The liquid it produces is an odourless mix of humic acid and nitrate. I find UDDTs as public toilets require continuous maintenance since most people don't know how to use them.

I recorded a testimony for the State of Vermont just on this question of composting toilets some years back.

Regards

Arno Rosemarin PhD
Stockholm Environment Institute
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