As part of the Mbabane Dry Sanitation and Waste Management Project, we are currently undertaking a community driven urine fertilization research. We have designed a simple odor trap using elastic balloons (the good ones!) that are connected to elastic bands which are in turn tied to the urine directing funnel. The elastic strings are stretched a little bit so that the balloon is press put on the funnel. The buoyancy of the urine water lifts the balloons and the buoyancy force extends the elastic string. This allows the urine to flow down the gap that is created. After the urine pours down the balloon is pulled back to its position by the elastic string. The strings should not be stretched too much as this will require a higher buoyancy force to lift the balloon and later on some of the urine still remains on the funnel while the balloon shuts. However, this can be arranged by common sense. Moreover, this seemed to be a problem only on the initial plastic funnel we used for conceptual development (photo shown). Later on we went to the local artisans and gave them a cone development drawing (thanks to the second year technical drawing course that i took 30 years ago) on thick paper from which they were able to manufacture the cone funnel of desired size from galvanized sheet (hope this works for some years). The urine goes easily through the funnel and retention is not a problem in the larger funnel. Second photo is also attached.

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The attached paper with photo's is another pingpong valve which was designed to block air. This was developped in 2011 for a project in India. The airlock worked well. To minimise urine residue in the siphon a little water may help.

Hi Florian,

I always observe some posts or comments/activities from you on SUSANA forum and am always curious to talk to you but did not succeed to acquire your personal e-mail address.

I am Krishna from Nepal currently living in Honolulu, Hawaii (USA). If you still remember, we got a lot of help from GTZ (ecosan team) and personally from you for the ecosan conferences that I organized in Kathmandu, Nepal, back in 2005. We also met in GTZ Eschborn headquarters during a workshop and I still remember you taking me to the festival in Frankfurt (I guess) in the evening.

Could you please forward me your e-mail address? Thank you

-- Krishna Lamichhane Honolulu, Hawaii, USA

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Hi,
I add two more photos of the mentionned test urinal in our office. I also checked for the slope of urine pipes, we use 2.5 %. Urine pipes are also ventilated (connected to the vent pipes ventilating fecal collection chambers), this hasn't been done previously.
Best regards,
Florian

Ecowaters - for the purposes of this thread are you able to post a photo or a link showing what you refer to as a "Tyvek strip trap" and/or provide some info on how to go about DIY'ing such a device?

Thanks!

I would second what Florian said: if the ball is not lifting it is likely because the opening it sits in is too large. The Rich Earth Institute has developed a portable waterless urinals using the ping-pong ball trap, and distributed many of them to our participating urine donors. The ball covers an opening slightly less than 2 cm in diameter, and it lifts very well. Previously we had trouble because the opening was too large and the ball did not lift.

--Abe

Hi,

thanks for the reply and your comments.

The smell trap works perfectly, I've tested it myself in the pilot device, which is installed in our office in Molodva and used by all male staff since 4 months. The ball lifts without problems, smell is well contained.
The questions is how long does it work well before ball and/or rubber seal needs to be changed.

If it has not worked for you, perhaps it has to do with the ratio of diameters of the ball and the sealing?

As for the urine piping, I agree it looks like the slope is not much. It's not horizontal though, I think it has about 2-3% slope. Our installations are relatively large at times, with several toilets cabins in a row, and slope needs to be optimised. I think our engineers just apply the same slope in all pipings, even though in the urinals shown in the picture, there would be enough room for a stronger slope. In our experience, 2-3% works quite well. Important is that slope is constant and that there are no horizontal bits. Of course strong slopes like 20 degrees would be on the safe side but this is not feasabile in buildings with 10 to 15 m of lenght.

Best regards, Florian

Thanks for these photos.

The ping pong ball "lifting trap" approach has not worked for us. The ball does not lift.

However, one person tells me it works for his urinal.

These are interesting urinals. I would install the connecting urine line with more slope to it--angled at least 20 degrees.
Urine will pool in a horizontal pipe and sludge will accumulate. This will create odor. We had this experience with poorly installed Wost-Man Eco-Dry urine-diverting toilet stools. We had to re-install the piping.

Hi,
I would like to share photos of a ping pong ball valve that my colleagues in Moldova now are testing in the school toilets supported by our project. So far we used condoms, the hope is that the ping pong balls work longer before they need to be replaced. It's done with ping pong balls and simple PVC pipes and rubber sealings.
It has been tested on pilot scale (cherry can urinal in our offices) for a few months and is now tested in real scale in some new school toilets.
Best regards, Florian

In the United States, various waterless urinal traps have been on the market. Most are mineral oil traps, but in simpler urinals, the rubber or "condom"-like trap appeared for awhile then was replaced by the Tyvek-strip trap. You could easily make your own.

Ecovita has sold about 400 simple waterless urinals with no trap. If the urine drains to gravel or to a tank with an angled pipe, urine odor potential is reduced.

Note the Wost-man urine-diverting toilet now features an odor trap in the urine drain.

When I worked in Trichy, India, I received an example of the urine valve shown in the picture. The casing and the funnelholder is from PVC and the soft plastic tube seems to be nylon, but I am not sure. I guess a durable material will be Goretex; since only a very small quantity is needed it may be commercially interesting. The texture of the tube has a very fine grain, possibly minimising it to stick together. The three scews are stainless steel. The funnel can be should be easy replaced when stuck and costs only a few cents. The whole thing costs less than a Euro in India. I am not working with the project, but more information can possibly be obtained from Mr Subbaraman, This email address is being protected from spambots. You need JavaScript enabled to view it. from Scope Agency.

The second photo is a combination with the closng funnel and oil seal. The point with oil seals is that the (eventual) washwater flow in the drain should be slow so the oil stays on top.
Re-using condoms (if they have been used as condoms) as suggested by smecca is a bad idea, sorry.

We have experimented with the "condom" trick as a differential valve; it works quite well - doesn't cost 30 Euros, is available everywhere, is open source, is readily replaceable and (some would say) is a reuse for the device.

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