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

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

kimgerly wrote: I would like to dovetail on Dr. Hill’s comment in a previous post, "What is missing in these forums are the voices of people & agencies actually operating these units.”

First. Yes, composting toilet is a misnomer, as per points thoroughly enumerated by Dr. Hill.

Second. I would like to be one of the voices that can testify about is an eco sanitary, thermophilic compost toilet system operating in Portland, OR, USA. A paper I co-authored titled, "The Kailash Ecovillage project converting human excreta into organic foodstuffs and sanitized compost using new international building codes for compost toilet and urine diversion systems” was submitted for final editorial review just yesterday for publication in the forthcoming, first edition of IWA’s Blue-Green Systems, Ref: BGS-EM192R1.

This experimental composting toilet system modeled after the Water Efficiency and Sanitation Standard (WE-Stand) set forth by the International Association of Plumbing and Mechanical Officials (IAPMO); it has been operating since March 2014. We call the humanure excreta collection device the commode AKA Joe Jenkins’ Lovable Loo. Urine and human excreta are hot composted (thermophilic temperatures) in a dry-composting toilet processor system for eventual use on the community’s organic gardens. The system consists of urine collection vessels, multiple portable collection containers/commodes for excreta, toilet paper, cover material, and a compost processor. Logs returned sustained thermophilic compost temperatures. Compost and urine pathogen testing met American National Standards Institute (ANSI) and National Sanitation Foundation Standard 41 (NSF 41) requirements.


Unfortunately this is part of the problem - there is no real reason why Jenkin's humanure system should ever meet western standards. It's a basic system where limitations of added carbon and oxygen should limit the amounts of composting and pathogen kill.

And yet somehow it is still reported regularly that the system works.

So the question is why it works.

My view is that it is a combination of things - but most likely that the materials used did not have high levels of pathogens in the first place (and they were not spiked during experimentation), that the standards do not consider highly resistant pathogens that are not common in North America and that the reductions in pathogen counts (I can't remember the detail but I think the requirement is a certain log reduction) are fine if there aren't many pathogens there in the first place but nothing more than you'd get from normal die off in an enclosed container in six months.

In anything other than essentially optimal conditions, I can't see any reason for believing that it something that should be replicated, encouraged or even attempted.
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  • geoffbhill
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Re: Which composting toilet to choose - recommendations, please?

Having read through everyone's comments and pondered this topic, I have these questions of SuSanA and this forum:

1) what is the objective of this forum? Provide a place to share popular information (with limited peer-review) or deliver a public service towards increasing human health and protection of the environment (higher and more important level of peer-review)? If former, fine, call composting toilets composting toilet because of the history, familiarity, and warm fuzzy feelings this gives people when they sh!t and toss in sawdust. If the latter, then consider that there are no well documented cases where composting conditions (definition = thermophilic) occur in a vessel under a toilet seat, and thus the only reasonable thing to do is eliminate "composting" from "toilet", for the sake of human health. The definition of composting is already well set in the science and engineering literature and necessitates a thermophilic step. Continuous compost reactors (usually drums or tunnels) used in the industrial world run consistently at or above 55C. Compost toilet chambers run at ambient temperatures >99% of the time. Thus they are not composting and they do not produce compost. The reasons for this are many and described earlier and cannot be overcome except in highly managed situations such as lab experiments.

If we do our best to eliminate the term composting toilet I think this could be a structure that works:

Flush Toilet
- water to sewer or septic tank/field
- tiger toilet (pour flush)
-could be urine diverting or not, with flush water in either side

Dry Toilet (no water)
-urine diverting OR mixed waste
-toilets with or without additives (some need no additives like Ecodomeo urine diversion conveyors, some have ash / lime for pathogen destruction, some use sawdust to absorb urine if mixed waste)

There are a myriad of process than can be done to the waste from these two broad groupings, and there could be 5-10 toilet systems under each sub heading of Dry Toilet, but these can be sorted and grouped in sub categories underneath the major headings (Dry toilet - urine diverting OR Dry Toilet - mixed waste), as these types and technologies will come and go.
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  • joeturner
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Re: Which composting toilet to choose - recommendations, please?

I suppose I can believe the reports that faeces in small boxes are composting - but it does seem to me to stretch credibility and logic.

Personally the only system I'd have confidence was actually composting would be a regularly turned windrow - and even there I believe there is evidence that areas which have not reached temperature can re-inoculate areas which have.

The reason is that I believe you need the volume and correct C:N ratio to reliably get to high temperatures needed to kill pathogens - plus sufficient oxygen to allow aerobic microbial respiration. I think there is good evidence to show this in the academic literature and only anecdotal evidence supporting the idea that small, enclosed,composting toilets actually do any kind of treatment n a reproducible and reliable way.

But changing anything seems like a monumental task given how many are distributing these kinds of system.
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  • kimgerly
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Re: Which composting toilet to choose - recommendations, please?

Preface: I reiterate, this paper I mentioned in a previous post is currently under final editorial review, awaiting publication in the forthcoming IWA Blue-Green Systems Manuscript Number: BGS-EM192.

@joeturner, allow me to add some concrete performance results. For now, here’s what I can share…

After humanure was collected from the Joe Jenkins’-style 5 gallon collection vessel AKA container AKA bucket, typically, 15-20 containers were batched into a compost processor consisting of several large bins constructed of durable, unmortared concrete blocks, with a bottom constructed of a lipped concrete pad sloped toward a drain in the center to collect any leachate; any leachate was recycled into the processor. Bin interior dimensions 1.2 x 1.2 x 1.1 metres with an internal capacity of ~1.6 cubic metres.

Compost temperatures were monitored for several bins daily, after each batch of compost was added to a processor bin. Temperatures were taken at the center of the bin, 10 cm from the edge, and the internal edge of the bin, at the depth of the compost thermometer, which was 50 cm long. Even at 10 cm from the bin perimeter, the extent of the excreta, toilet paper, and high carbon additive (moist wood chips) mass being composted, temperatures above 40°C were sustained for 28 days, and above 50°C were sustained for 10 days.

As far as compost pathogen testing for fecal coliforms, results produced demonstrated a high-quality product, exceeding the US Environmental Protection Agency (USEPA) standards for Class A biosolids (<1000 fecal coliform cfu/g) for compost safety; specifically <1-20 cfu/g.

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  • geoffbhill
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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)

Great work!

This is composting in a batch process using human waste as a feedstock. This type of batch process and attention to mix can reliably achieve thermophilic temperatures.

Bucket collection of human waste is not a composting toilet.

Batch Composting is being done (process) to human waste collected dry (no flush water) and transferred elsewhere for separate processing. This is not a composting toilet. In other words the batch composting of toilet waste is not a composting toilet. I blame long term poor use of this term on the misunderstandings that abound.

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

Ok, can you tell us where and how you sampled the temperatures and where you took samples for analysis?

Because if one sticks a thermometer into the top-middle, it isn't hard to show high temperatures. It is much harder to show that all of the material has reached temperature - that normally requires thermocouples and continuous temperature collection over a significant period.

Coliforms are probably the worst thing one could measure - even if it is what the USEPA standard suggests.

Other more resistant pathogens are in no sense modelled by coliforms. EU standards specify particular microbes like strept - and that is largely because it is assumed that the nastier pathogens are not present.

I still strongly suspect that if tests had been more extensive then a Jenkins' humanure style system would not be killing resistant pathogens.

Generally speaking if one is trying to prove that a specific system is working, a range of microbial samples would be taken at different times for a suite of microbial pathogens - even if in the normal way it isn't possible to test each of them.
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  • kimgerly
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Re: Which composting toilet to choose - recommendations, please?

@joeturner. I don't want to offend the IWA publishers and make ALL information available until the paper achieves the final 'blessing' for publication; soon on the publishing, I hope. I also understand your reservations about the full swath of pathogens being eradicated. Allow me lower your expectations...

We did employ a best-practices procedure for drawing final composted samples, and using commercially available test kits to (key operative) benchmark this design schema.

NB: Our offering is a cursory, starting point prototype/pilot, solely funded by sweat equity. Unfortunately, here in the USA, agencies and municipalities are solicitous to fund ANYTHING until provided with a pilot. The aim of this pilot is to garner financial support for a more extensive final analysis of the end product, AND a variance that adheres to IAPMO WE-Stand AKA Green Building Code in the USA and Canada, so more rigorous analyses and results can be produced--the aim of my meeting tomorrow with the California Water Resource Board and California Recycle Professional Engineers.

I trust you can understand. Stay tuned...

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

Well I guess it is possible that you have been able to find a "sweet spot" where adding wet faeces with a high N level to a wet carbon source in a confined space is able to promote aerobic microbial respiration and effectively fully sanitise the product.

Logic suggests that ought not to be possible.
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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 agree with Geoff, let's dispense with the term "composting" toilet and instead use, as applicable, "flush" and "dry". Maintaining use of the phrase "composting toilet" is irresponsible and, as Geoff has rightly pointed out, so obviously flies in the face of the core tenets of SUSANA and its pursuit of improved public health.

Kai Mikkel Førlie

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  • goeco
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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)

Hot composting has so many variables that influence the outcome... the volume, the c:n ratio, oxygen levels, moisture levels, ambient temperature, heat exchange... in particular oxygen levels over time because these require replenishing, usually achieved through mechanical means. The interaction between variables, particularly volume and oxygen levels would be inherently difficult to consistently reproduce. I'd suggest that sample size would need to be very large to "prove" that a specific method of hot composting "works".

But in the end it is resulting pathogen levels that matter, the outcome not the process. The one tried and true method for destroying pathogens involves the variable time. High temperature is not required to destroy pathogens, provided you're willing to wait. The difference is that time is 100% reliable. The other variables don't really matter when time is involved.

In order to make compost there needs to be a thermophilic stage.


Not true.

Compost is better defined as the product, i.e. "safe, stable, mature" rather than any specific biological process to achieve that. If I make a toilet that does not involve a thermophilic stage, but I design it so the decomposed waste rests for 2+ years before being handled, why shouldn't I call it a composting toilet?

I would suggest that Elisabeth updates her definition to:

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 humus-like material, but may not destroy all pathogens. A pathogen-removing composting toilet includes processes that destroy all pathogens.


If there isn't decomposition then it isn't a composting toilet. Dehydrating human excreta doesn't involve decomposition and the result isn't a humus-like end product.

Dean Satchell, M For. Sc.
Vermifilter.com
www.vermifilter.com
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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)

High temperatures absolutely is required to kill some of the worst faecal pathogens in a faecal composting system.

Other effective systems exist. But "composting" at low temperatures with storage isn't one of them.
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  • geoffbhill
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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 US Composting Council (USCC) recently updated the definition of Compost to include the thermophilic process. They did this to protect public health from various compost producers who were negligent in adhering to pathogen reduction processes yet still able to market their (questionable) material as compost. Thank you to Ron Alexander.

wasteadvantagemag.com/uscc-efforts-resul...by-regulators-group/

Pathogen destruction through time is highly dependent on site, moisture, pH, and temperature. Time to destroy ascaris ova can be multiple years. This is not a reliable method. Most composting toilets are operated as continuous flow. Material added to top seeps down to bottom (oldest material) with urine / drainage. So time is not really achieved even here.

If material is pulled out to batch treat by "time" the operator might as well do a "Jenkins" batch compost process by adding bulking agent. Heat destroys pathogens many orders of magnitude faster than "time" treatment.

Geoff Hill
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