Treatment of residuals from composting toilets without soil contact
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TOPIC: Treatment of residuals from composting toilets without soil contact

Treatment of residuals from composting toilets without soil contact 04 May 2014 13:58 #8440

  • Kevinkuhn
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Hello,

I want to ask you to gather composting techniques which can be applied without soil contact. The background is that the legislative situation in Germany is still not 100% clear about the composting of human waste. Though it is allowed in most areas on a private scale, there are no case studies about large scale composting (as far as I know). Concerns by the administrative are mostly the contamination of soils and ground water, regardless of the usage of the end material.

So my thought is to do composting without soil contact. This 'alien system' would need a blocking layer beneath to avoid leaching and, I guess, some added soil would need to be added. In the end the composting process is mainly done by micro-organisms and worms. So one would need to inject these to the alien system.

Therefore, I want to ask you if you have any experiences with such composting systems? How long does it take, compared to natural composting (in temperated climate)? How is the quality of the manure at the end? Does anyone have construction plans or photos of such a facility?

I'm mostly interested in treating residuals from composting toilets (feces+urine+wood chips+other necessary materials may be added). These are the most common dry toilets in Germany and are used for music festivals next to chemical toilets, but there is no legal disposal so far. The german environmental agency is promoting regaining of phosphorous from excreta and seeks for a long-term strategy to get independent from importing P. Therefore there is a collaborate need to create reliable, cost-benificial, safe, and legal systems to promote dry-toilets in Germany/Europe.

I am looking forward to your thoughts

Kevin
Non-Water Sanitation e.V.
www.nonwatersanitation.de

EcoToi - Rental for composting toilets for festivals and construction sites in Berlin, Germany
www.ecotoi.de

Re: Treatment of residuals from composting toilets without soil contact 04 May 2014 21:30 #8444

  • joeturner
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Windrow co-composting of faeces is very common on concrete. There is no need to inoculate with soil as the necessary microbes are already present in the faeces. Quality is variable dependent on factors such as weather, liquid in the faeces, quality of C-rich material etc. However, well functioning windrows can get to acceptable pathogen levels within 8-10 weeks with regular turning. Usually these are left subsequently to mature once stabilised.

This is a large scale site in Austria www.compost-systems.com/en/referenzen/lienz

I have not looked, but I'd be surprised if there were not large windrow composting sites of sewage sludge in Germany.
I don't work for anyone, I am a philosopher interested to think about how we think about WASH and sanitation. All thoughts are mine alone, I am responsible for any errors.

Previously trained and worked as a Soil Scientist and worked on projects composting sewage sludge.

Re: Treatment of residuals from composting toilets without soil contact 07 May 2014 11:44 #8506

  • canaday
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Hi Kevin and Joe,

Joe, how do we know that the necessary microbes are already in the feces? Do you have a publication to support this idea? I would guess, offhand, that many soil organisms cannot live in our guts, especially important varieties of fungus.

I would also think that a good community of microbes may develop over time on whatever floor is being used.

Also, in this interview about UDDTs
(www.chekhovskalashnikov.com/human-waste-disposal/)
I cite several papers showing that finished compost is one of the best cover materials for controling smell. This would also inoculate new feces with beneficial soil microbes (and potentially earthworm eggs?)

Kevin, do you think there is any chance of introducing Urine Diversion to those toilets for better phosphorus (and other nutrient) recycling and reduction of the potentially risky leachate.

So, a cement floor might be fine ... and the leachate could be treated via Constructed Wetlands.

Best wishes,
Chris Canaday
Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
inodoroseco.blogspot.com
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Re: Treatment of residuals from composting toilets without soil contact 07 May 2014 12:05 #8508

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Chris, all the large windrow faeces composting I've ever seen has been done on concrete, and there has never been any need to inoculate to drive the composting process. I therefore conclude that all the necessary microbes are either in the sludge or naturally incoculate it via the air.

It has many advantages, including the control of leachate. Many large systems have channels cut into the concrete to pump air into the windrows, but these could also be used to collect leachate. This may or may not be an issue depending on how much liquid there is in the original material to be composted - although if the faeces is too wet, it is unlikely to be economic to compost it as the amount of extra carbon-rich material needed to 'mop it up' will be very expensive. Most large systems will have some kind of system to dewater the sludge before composting, but I agree that urine diversion would also be a good choice. In a properly functioning windrow, I wouldn't expect to see much leachate as the temperature tends to drive off moisture - particularly whilst turning. Some systems actually collect any leachate and pour it back onto the windrow.

Worms are not found in hot composting windrows because they can't stand the temperatures, but finished compost is often stored on the soil without contamination problems and is often full of earthworms.
I don't work for anyone, I am a philosopher interested to think about how we think about WASH and sanitation. All thoughts are mine alone, I am responsible for any errors.

Previously trained and worked as a Soil Scientist and worked on projects composting sewage sludge.
Last Edit: 07 May 2014 12:07 by joeturner. Reason: language

Re: Treatment of residuals from composting toilets without soil contact 07 May 2014 14:07 #8512

  • Florian
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Kevinkuhn wrote:
Concerns by the administrative are mostly the contamination of soils and ground water, regardless of the usage of the end material.


Just a small comment to add: Kevin, these concerns are not really specific for treatment of feacal matter I think. Rather it is a very normal and standard requirement, that treatment facilities of any type of waste need to make sure there is no leakage or run-off to the environment.

Legal problems with dealing with human waste are most probbaly related to the use of the end product.
Florian Klingel
Water and Sanitation Specialist at Skat Consulting Ltd.

Re: Treatment of residuals from composting toilets without soil contact 09 May 2014 00:56 #8529

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Manure from any source is perfectly safe if composted properly. On a personal scale read The Humanure Handbook by Joe Jenkins (available online) His toilets consist of a bucket and a carbon source such as sawdust or bagasse (sugarcane) plus liberal amounts of straw in his compost pile. Buckets are emptied into the middle of the pile which quickly reaches temperatures of up to 60-65 degrees centigrade.

Even here in the US with its overkill rules and regulations, 121 F for three days is considered adequate to eliminate pathogens.

On a commercial scale, have a look at www.lawpca.org/. This facility is in Maine and it collects sewage sludge and sawdust which is placed in 210 foot long covered tunnels and turned daily for 21 days at which point it falls into a pit and is taken outside to mature for a couple of months. The end product is used by landscapers and individuals.
Saving the earth one compost heap at a time.

Re: Treatment of residuals from composting toilets without soil contact 12 May 2014 09:38 #8579

  • Geoffroy Germeau
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Dear Kevin,
We have the same issue in Belgium where it is not clearly admitted to compost fecal material on large scale. On private garden (home scale), people do what they want but a "processing path" is necessary if separate option should be promoted. On big scale, concrete floor is inevitable, and there are lots of required parameters to be analyzed to prove the product is of good quality.

We are trying to make a compost test of mobile toilet (not dried one because of availability), in a compost facility (concrete floor) to prove the quality of the compost. We wait for the administration's agreement. All the actors we met agree with the fact that the trial should be done on a minimum scale of about 100m³ to get temperature elevation.

We don't think it could be economically viable to co-compost with woodchips/sawdust/straw on big scale, so we'll try to co-compost with usual green "waste" used in the compost facility.

We got contact with Orgaworld in the Netherlands (www.orgaworld.nl) that told us the usually co-compost fecal material

In France, Meuse Compost (www.meuse-compost.com/) told us they sometimes co-compost fecal sludge with other ogranic wastes.

In France also, Trecofim (www.trecofim.com/) has a kind of co-compost facility that treat liquid fecal sludge with organic material. We wanted to visit it but we still couldn't find agreement on this..

It would be great to have/create a summary of existing facilities and technical possibilities to co-compost fecal material, that could be used to widen the legislation in European countries.

Also, it would be great to get/make a kind of manual of good practice of composting in home scale.

If anyone can help with this,

Thanks in advance,

Geoffroy
Exposantd asbl - Pôle Assainissement Durable
90, Rue du Mont Saint MArtin B-4000 Liège (BELGIQUE)
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Re: Treatment of residuals from composting toilets without soil contact 12 May 2014 16:27 #8585

  • Kevinkuhn
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Thanks to everyone for the input!

@Geoffroy: Your test sound really promising. I am curious to see the results from that. I tried to check the websites you cited, but my dutch and french is very basic. However, I really like the idea of co-composting of fecal matter. The material from composting toilets is still quite wet and adding another material could reduce leaching. I also like the concept by Trecofim.

I agree with you, that there should be a compendium of facilities and technologies available in Europe to promote nutrient regaining from fecal matter. Do you know if anybody is currently working on that?

@compost: I really like the facility of Lawpca. That sounds like a perfect system, including the sale of compost at the end of the processing. Joe posted a system in Austria where they treat the matter 8-10 weeks, to make sure that pathogens are killed. Both systems work similar but the processing rates are quite different. Do you have an explanation for that?

I could´t find any helpful pictures about the site and how they constructed it, but it sounds like a large facility with high investment costs. However, I am still looking for an low-cost option.

@ Joe and Chris: Indeed, I also prefer urine diversion, since it creates a more valuable product. But, they are not really common here and people don´t use the properly. Therefore the easier system of composting toilets are used, i.e. for mobile toilets. Perhaps in future there will also be mobile UDDTs.


Thanks for the input so far and I am interested in new insights and ideas from you.

Kevin
Non-Water Sanitation e.V.
www.nonwatersanitation.de

EcoToi - Rental for composting toilets for festivals and construction sites in Berlin, Germany
www.ecotoi.de

Re: Treatment of residuals from composting toilets without soil contact 12 May 2014 17:01 #8586

  • Geoffroy Germeau
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Kevin,

I don't know anybody writing a compendium about composting of fecal material, but it would be great to do it, on house-scale (how many times is it necessary to turn the pile, good or not to mix with other organic wastes, how long time, etc.) and bigger one. I would be glad to participate to such document with other people. Anybody in of the Susana team would like to coordinate?

the concept of trecofim is also used by other enterprises (like "Coved" in France) since the end of the '90s. The use the process for "wet" sludges from home-scale WWTP. it could be used for urine, but there might be loss of N. As far as I know they use straw or sawdust, which are (more and more) valuable products.

About urine diversion, a friend tried to absorb 1/4 liter of urine and it needs 1 liter of sawdust. For the festivals, he claims that if he know how much liters of beers are to be sold, he knows how much sawdust he needs to absorb the urine!

In Belgium too urine diversion is not easy to implement in public facilities because people don't know it; systems with drainage which produce lixiviat might be easier to implement.
Exposantd asbl - Pôle Assainissement Durable
90, Rue du Mont Saint MArtin B-4000 Liège (BELGIQUE)
Courriel : This e-mail address is being protected from spambots. You need JavaScript enabled to view it
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Re: Treatment of residuals from composting toilets without soil contact 12 May 2014 17:07 #8588

  • joeturner
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Kevin,

The difference is that in order to satify European sewage sludge regulations you would have to be able to prove that all of your windrow has met the standard for pathogen destruction. Whilst it might be true that pathogens are killed at 121 F for 3 days, the fact is that not all of a windrow will get to that temperature during the time period. Anyone can find areas of the windrow which have reached high temperatures, the problem is proving that all of it has.

And of course it is an almost impossible task. Hence large compost producers will turn the compost with industrial compost turners several times a week for 6-10 weeks in order to ensure that every part of the windrow has reached the area of high temperatures. They will have to show that the pathogens have been destroyed to safe levels using batch testing of the compost.

As a further note, I would say that without urine diversion or some kind of dewatering of the faeces, composting will not work adn you are very unlikely to satisfy any regulator in any EU state that it meets the criteria set down in the EU regulations and directives.
I don't work for anyone, I am a philosopher interested to think about how we think about WASH and sanitation. All thoughts are mine alone, I am responsible for any errors.

Previously trained and worked as a Soil Scientist and worked on projects composting sewage sludge.

Re: Treatment of residuals from composting toilets without soil contact 14 May 2014 09:35 #8613

  • Geoffroy Germeau
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Dear all,

Even if urine diversion is surely a good solution to lower the water content, it should be possible to co-compost toilet content with "green wastes".

The idea would be to pre-compost the "green wastes" on a normal way during 1 month to get it dryer, and then to incorporate the toilet residues mixing the windrow. The windrow will then be left to compost during 2 month, with measured temperature and mixing. Samples will be taken at the end, randomly to verify the quality (agronomic, chemical and microbial parameters).

The protocol has just been approved by the administration in charge of food safety.

We think that the issue is about the ratio between toilet residues and the co-compost.
This kind of experiment has been done before with bad milk (I don't have the paper), showing it was possible. But we have very few information about the process.

We hope it will work. The trial will begin within 1-2 month. I'll write here about the result. If anybody has more information about this kind of composting, please share!
Exposantd asbl - Pôle Assainissement Durable
90, Rue du Mont Saint MArtin B-4000 Liège (BELGIQUE)
Courriel : This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Site web : www.exposantd.be / www.assainissement-durable.be
Last Edit: 14 May 2014 10:11 by muench.

Re: Treatment of residuals from composting toilets without soil contact 16 May 2014 00:05 #8630

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Hi Geoffroy,
We use a closed system ,
waste goes into wheely bin, ( composted with worms )
urine goes to tank that is pumped out ,
then used for making struvite ...
Nothing needs to go into ground ,
regards Andy
melbourne
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