H不， Abe:
I have tested a UDDT in a holet since 2008.
The urine pipe in the toielts in less than 15mm. We use the normal toilet cleaning detergent to clear the deposits.
best regards
Scott

Dear Elisabeth, dear Arno, dear Fedde,

I fully agree with your statements, concerning installation and maintenance of urine diverting flush toilets. We sold nearly 150 UDT Gustavsberg water saving toilets, which are unfortunately no longer produced since 2011 because of the low quantity of sales. The production was stopped right at the time, when our sales were increasing.

We made some technical changes with the Gustavsberg toilet to simplify maintenance and to avoid clogging of the urine pipe (stainless steel urine pipe, screen for urine discharge, hand-operated pump for regular cleaning)and we have very good experiences as long as regular maintenance is assured. Most of the projects we have supplied, are research projects (Ghana, The Netherlands, Australia, Germany, Vietnam and others).

There are new developments under progress by some sanitary manufacturers, but not on the market yet. As soon as there is a legal breakthrough for urine recovery on a large scale, there will be a big market for urine diverting flush toilets and dry toilets as well. Sweden is a forward-looking model for other countries in recycling nutrients from urine for agriculture. Until then, everyone who has a private garden, is able to recycle his/her urine on a legal basis by using a dry urinal or a dry toilet with urine separation. However, before planning urine diverting facilities, the different options for urine application should be considered.

Best regards

Wolfgang

Arno: I would propose some real estate developers to install UDTs after a 10 million RMB turnover apple business to collect the urine for local farming,local customers.

Hi Abe,

Within projects together with www.WECF.eu we implemented 40 school toilets and over 1000 household toilets. I monitored them in Central Asia for 4 years.

According to my experience: the pipe diameter should be at least 50mm also for single toilets. The slope we never researched but it was clear that 1% is a risk for clogging. 3% seems to me a minimum. The pipes should very smooth inside. Normally pvc pipes were use. Also it can be recommended to rinse the pipes with vinigar to avoid cloging by urine crystals.

I hope this experience is useful for you.

Best greetings Fedde

Hi Arno

You wrote - "...Urine from the body is essentially sterile and a perfect fertiliser for plants..."

Have you considered using the urine to grow Diatom Algae in containers like plastic bags or aquarium tanks. This can be placed just outside the toilet wall or can even be used as the toilet window. In a high rise building, the urine from 10th floor can be treated on 9th floor and reused for toilet flushing on the 8th floor and so on.

Diatoms are very good food for fish and can be used to grow fish or they can be harvested for nutraceuticals, Omega-3, etc. We have a very good process to grow diatoms using urine. We are looking for people to collaborate with, we need partners who can set up the urine supply and also people who can use the Diatoms.

Regards

Bhaskar

Here is my input on the discussion about urine diversion flush toilets for office buildings in the USA:

The key to making these sanitation systems work is care in installation and regular maintenance. Most (urban and office) people assume they can continue to flush and forget and let someone else take responsibility. Also plumbers are not experienced in designing systems for urine since they think in terms of water locks and small slope gradients.

Urine is the main challenge since it is a much more voluminous product than faeces (ca 10:1). Urinals for both men and women are the first thing to install. There are many waterless urinals with relatively good odour management on the market. As to UDTs (urine diversion toilets), there are very few porcelain models – mainly Swedish and German. The most successful double flush ones in Sweden come from two companies: Wostman Ecology wostman.se/en/ and Dubbletten www.dubbletten.nu/home.html.

Separett is the most successful of all when it comes to dry UDTs (ie UDDTs) and it specialises in plastic models. www.separett.com/ These are robust, relatively simple to use and can be used in offices. They can also be modified to drop into bins below the washroom floor. Odour management is the prime feature of the Separett models that have a built in small fan. The success of these toilets is almost always centred on odour control.

In almost all cases it is the urine systems that is the killing factor in UDT projects. Urine will block pipes if allowed to stand for too long. My own recipe is to have no dips or water locks but to discharge sharply into the storage tanks. The mouth of the pipe should always be submerged to prevent a chimney effect (easily done by fixing the mouth of the pipe into a small container or bucket that never empties).

The UDT project needs to be set up backwards. Solve the challenge of what you will do with the collected urine eg a farmer. Then figure out how much he/she can use and how often. Seasonality means storage so your best friend will be someone who grows year round using a greenhouse during the winter. EAWAG (Switzerland) has developed methods for nitrification and distillation to reduce ammonia loss and reduce volume. See forum.susana.org/forum/categories/98-res...and-and-south-africa for their VUNA project.

I presume you will be flushing the faeces into the sewer system and collecting the urine separately. GIZ did set up such toilets some years back including dry urinals. The manufacturer for the UDTs was a company called Roediger Vacuum. I am not sure if they still make that model or have gone over to only vacuum systems (actually, based on what Elisabeth wrote above, they have stopped making NoMix toilets and are focussing on their vacuum toilets; I didn't know that).

Alternatives are to use vacuum toilets with or without urine diversion to reduce flush volumes. There are some Chinese models that are also UD (urine diversion). The aim in sanitation is containment and treatment (something that most treatment pants around the world fail to do properly). Adding greywater and storm water to flushed water makes for gigantic volumes – something the older cities of the world cannot cope with.

Remember the average human produces 50 L of faeces per year and 500 L of urine. The solution for faeces should be a solid waste one with thermal composting, combined with food wastes in biogas reactors, etc. For hospitals incineration toilets are advised. Urine from the body is essentially sterile and a perfect fertiliser for plants. Ideally the urine should be piped directly into gardens. Lots of options. Lots of ignorance. It’s all taboo so progress in this area is slow.

In summary: We have lots of experience with double flushing UDTs in Sweden. Problems result in urine pipes not being built properly nor are they maintained resulting in blockages. All plumbers know nothing about how urine behaves in pipes.

-- Arno

Dear Carol,

You wrote:

Although I agree that urine-diverting flush toilets likely will not replace existing flush toilets in the near future, urine-diverting flush toilets have a place in the wide array of ecosan options and should not be discouraged by researchers with experience limited to grant-supported projects.

I was not sure how to take this, whether to be offended or not, but in any case I don't see myself as a "researcher with experience limited to grant-supported projects".

The SANIRESCH project that I mentioned was indeed a research and demonstration project with the aim to study in detail and over the longer term (4 years), the operational aspects of waterless urinals and urine-diversion flush toilets of a certain kind (the Roediger NoMix toilets). I think it achieved this aim and all the results are well documented online in the SuSanA library. Only few problems with the waterless urinals but many problems with these particular toilets in this particular office setting (other experiences have been made in other settings, like Kai pointed out above for his building in Switzerland). And better experiences may well have been made with the urine diversion flush toilets of other manufacturers.

I am more than happy to hear of such successful installations (long-term), worldwide.

You also said:

Elizabeth, remember there are many successful installations of urine-diverting flush toilets that are not chronicled on the SuSanA forum.

Of course you are right, the question is though how many is "many", and where are they exactly? A few years ago, I researched this question with my team by contacting all urine diversion flush toilets suppliers on the market at that time and asking them how many of their toilets they have sold and in which countries.

The numbers we collated in this document about urine diversion flush toilets:

von Münch, E., Winker, M. (2011). Worldwide listing of suppliers for urine diversion pedestals/seats (for UDDTs or for UD flush toilets) - Appendix 3 of technology review of urine diversion components. Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH. Eschborn, Germany.
www.susana.org/lang-en/library/library?v...eitem&type=2&id=1148

You can imagine this was quite a tedious task! If someone has the time, it would be great if they could update the figures because this is now from nearly 3 years ago.

Some suppliers didn't want to disclose this information (Envirosystems in China; Berger Biotechnik for the Gustavsberg toilet) (this is due to the competitive nature of this business; understandable). The others said:

• Roediger NoMix toilet (Germany): 420
• BB Innovations, also called Dubbletten (Sweden): "Thousands" - exact number not disclosed by supplier
• Wostman (Sweden): 8000 + 400 of their newer Ecovac model

So that is a fair bit. Would be interesting to know how many of these are in Sweden and how many of them in other countries. My guess is they are 90% in Sweden and 10% in other countries. Does anyone have a guess how many of them are in the US? In Australia? In Canada?

Kind regards,
Elisabeth

Elizabeth, remember there are many successful installations of urine-diverting flush toilets that are not chronicled on the SuSanA forum.

Although I agree that urine-diverting flush toilets likely will not replace existing flush toilets in the near future, urine-diverting flush toilets have a place in the wide array of ecosan options and should not be discouraged by researchers with experience limited to grant-supported projects.

Abe, many urine-diverting flush toilets are installed worldwide. Just 5 km from where I sit as I write this in California is a family home with two Wost-man Ecology toilets. Across the bay is another family home with a first-generation Wost-man Ecology urine-diverting flush toilet that drains to fertilize and irrigate the yard. Up in Vancouver, a third toilet (two are already installed) is going into a house where it will collect urine for a struvite-collection scheme.

Dena of Australia told an audience here in the United States last year that "urine diversion is dead. Long live urine diversion." Her evidence, she said, was that EcoSanRes no longer gets funding.
Also, her program struggled to explain to a plumber how to install one.
She also cited a public housing project that encountered user-acceptance issues. (It was established long ago in Sida publications and elsewhere that unfamiliar ecological technologies should not be prescribed in public housing situations. Usually we would not install wood-burning stoves in public housing, and eco-toilets are no different.)

The first and foremost problem we encounter with these---as with all new ecological toilets we install---is plumbers are not familiar with them and might not install them with appropriate slopes and traps unless we supervise or check their work. Odors and clogging can result. When this is corrected, the problems are corrected.
Other common issues are usage by small children and the need for user education. We supply child seats for homes with children.

Even in conventional waterless and water-flush urinals, drain lines are prone to eventual clogging, especially when groundwater is used for flushing. Appropriate slopes, line flushing, enzyme additives, and acid additives all help prevent this.

While writing my books on this topic, I have found---just as solutions activists like Cesar Añorve state---that ecological toilets are best demonstrated to the public as solutions it can elect to use. They should not be prescribed. The user who chooses the system has the most investment in its success. When these systems are prescribed, as we saw in the case of the public housing project in China with the much-publicized failures, there is less opportunity for user acceptance.

EcoSan systems installed where the user is the primary operator involve upfront maintenance that many are not accustomed to performing.

Also, some companies manufacture the toilets before understanding the nitrogen-reduction market. Waterless urine-diverting toilet stools, such as Wost-Man's, have a primary market in holiday cottages. This also is the main market for the self-contained composting toilets.
The urine-diverting flush toilets do not have this baseline market, so their manufacturers are relying on the denitrification market. This is not an easy one even for new ecological wastewater systems. (Witness the history of Solar Aquatics/Living Machines systems.)

At the same time, arbitrary factors come into play. The famous new ecologically oriented Bullitt Foundation building in Seattle, Washington was to have a waterless urine-diverting toilet draining to a composter. However, the engineer removed this from the plan because the toilet room was to be ventilated through the toilets, so the trap-less urine-diverting toilet stool would vent faster than the foam-flush toilet next to it.
This is why I now spend little time with architects simply seeking to add green features to their urban projects simply to get LEED and Living Building Challenge points.

So, Abe, with urine-diverting flush toilets, as with your composting toilets, your best chance at success is to keep it real and stick with installations with committed owners and pressing needs for zero-discharge wastewater management.

Hi Abe

At the moment, the following two papers are the best written sources of information about the NoMix system at Eawag:

Goosse, P., Steiner, M., Neuenschwander, W., Udert, K.M. (2009) NoMix-Toilettensystem. Erste Monitoringergebnisse im Forum Chriesbach. Gas Wasser Abwasser 2009(7), 567-574. (unfortunately only in German)

Lienert, J. and Larsen, T.A. (2007) Pilot projects in bathrooms: a new challenge for wastewater professionals. Water Practice & Technology 2(3).

We are planning to submit another publication soon (and in English) with further information about the NoMix system at Eawag.

About cleaning: we use diluted citric acid. In the toilets, which are flushed with groundwater, we have to use the citric acid once a month. In the toilets with rainwater, every two or three months is sufficient.

The following paper provides you with some information about precipitation problems in urine-conducting pipes and traps:

Udert, K.M., Larsen, T.A. and Gujer, W. (2003) Biologically induced precipitation in urine-collecting systems. Water Science and Technology: Water Supply 3(3), 71-78.

If you like, we can have a skype discussion together with Patrice Goosse, who is leading the monitoring at Eawag. Let me know.

Kai

Thanks so much, everyone, for your input! The SuSanA forum is such a great resource.

Carol: do you know of any resources for well-vetted maintenance plans for waterless urinals? The manufacturers all have recommendations, but I have spoken with facility managers who claim to have followed them and then were disappointed when they ended up clogging.

Nadira: how much water are the families using for a rinse? Is it just water, or is anything added? How long to you think the pipes are, on average?

Elisabeth and Christian: thanks for all those links! I've been reading through them with great interest, especially the many publications on the Saniresch website. To answer Elisabeth's question about funding, the Rich Earth Institute has a very small budget which comes from private donations and government grants. We dedicate most of our resources to managing, promoting, and documenting a regional urine collection and direct reuse project, which collected 12 cubic meters of urine last year. The code revision team is all volunteer, and is made up of a diverse group of policy specialists and people who work with dry toilet systems, pulled from a variety of companies and organizations.

Kai: thank you for the invitation! I have never had the chance to go to Switzerland, but if I am ever in Zurich I will certainly come for a visit. Could you explain more about your waterless urine collection system, or refer me to an existing account if there is one? (I am particularly interested in pipe diameter, slope, and any cleaning regimen, in addition to any other aspects that you think are relevant.)

Thanks to all,
Abe

Dear Abe

As Elisabeth pointed out, quite a lot of research results exist with urine-diverting toilets, although the conclusions of the different projects are somewhat different. Thanks to the various projects on urine diversion, we know that we (or the sanitary industries) need to develop better water-flushed and better urine diverting dry toilets. New plumbing codes would be extremely helpful. Therefore, I really would like to support your efforts.

Many research projects like those at Eawag or GIZ were done with water-flushed urine-diverting toilets. Depending on the type of toilets used, these results can be very helpful for you, because these systems also use separate pipes for urine and urine-collection tanks. However, many waterflushed urine-diverting toilets do not separate water and urine very well and in this case, you cannot directly compare the problems with scaling urine diversion systems without water flushing. In the case of the NoMix toilets at Eawag, only very little flushing water entered the urine pipes and in the case of the waterless urinals no flushing water was used at all. Therefore, we might be able to provide you with some useful information for the development of guidelines for urine collection systems.

Best, Kai

Dear Abe,

I just want to make you that you didn't miss previous discussions we had here on the forum about this topic of urine diversion systems in countries of the Global North.

As you will see from my posts, I am rather skeptical about it.
Here is an exchange I had with Dena and Kai, when looking at the situation in Australia and Germany/Switzerland:
forum.susana.org/forum/categories/34-uri...ydney-australia#3840

Here again a conversation about the situation in Australia:
forum.susana.org/forum/categories/34-uri...mit=12&start=12#6223

And here some discussions about the NoMix toilets which Kai mentioned in his post above, and the results from the Saniresch project:
forum.susana.org/forum/categories/34-uri...-in-eschborn-germany

I would like to point out that the Saniresch project, which ran from 2009-2012 led by Martina Winker, came to rather conclusive results (see link above).

My points would be:

1. Don't get overly optimistic about the potential of urine diversion flush toilets in the US. Unless there are certain parameters that are quite different from Germany, Switzerland and Australia?
2. I am yet to see a situation where the economics are there to make it economically feasible to install a urine diversion flush toilet system in a context where sewers and wastewater treatment plants somewhere in the vicinity do exist.
3. Forget about the NoMix toilets (see my previous posts about this). Yes, they may work at the Eawag building, but with a lot of tender, love and care. In any case, the company has stopped producing them, so you cannot buy them anymore (except from GIZ who is getting rid of them after the end of the Saniresch project).
4. If you want a urine diversion flush toilet, then I would look for a model that uses no mechanical valve on the urine pipe. Either use the design of the Wostman toilets (which allows for some dilution with flush water) or take one that has a simple one way valve like the EcosSmellStop (see here: forum.susana.org/forum/categories/106-us...and-and-austria#3702).
5. In my opinion, if urine diversion is called for, then rather go for a dry urine diversion toilet, rather than a urine diversion toilet with flushing (see Christian's post above regarding UDDTs). Admittedly, this creates totally different issues in terms of user acceptance.
6. If you are really after a flush toilet and want to radically save water, then maybe a vacuum toilet system is more suitable (connect to biogas reactor, like we have in some other projects, e.g. here: forum.susana.org/forum/categories/98-res...my-of-sciences-china

Good luck with it all!
(how is your institute and this work on revising the plumbing codes funded by the way? Just curious)

Regards,
Elisabeth