Urine infiltration /subsurface fertilisation in school UDDT

  • canaday
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Re: Urine infiltration /subsurface fertilisation in school UDDT

Hi Florian, (I tried to post this on Ecosanres, but for some reason it did not work.)

I have been distributing urine via perforated hoses for 12 years. You can read about this in my paper on Simple UDDTs in Sustainable Sanitation Practice
www.ecosan.at/ssp/issue-06-toilets/issue-06-toilets

Hoses can be under 10-15 cm of sawdust or sand for better aesthetics, less damage to the hose by UV light, less evaporation of nitrogen, less incidental damage from people clearing weeds, control of potential fecal contamination. At least in the rainforest, this also reduced the chances of mammals chewing holes in the hose to get at the nutrient-rich urine.

Benjamin Clouet's "Easy Shower" combines a shower into a UDDT, with drip irrigation hoses to distribute the urine + shower water


If Moldova is the least bit dry, it would be important to combine greywater with the urine, as Benjamin does.

Since Moldova is in Europe, the general consensus would be that you cannot do this, since the urine sludge(mostly stuvite) would reportadly plug the holes. I think the lack of meshes in most UDDTs also allows some amount of sawdust and other cover materials and would contribute to plugging, in combination with struvite.

Good luck with everything and please let us know how things go.

Best wishes,
Chris

Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
inodoroseco.blogspot.com
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  • Florian
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Re: Urine infiltration /subsurface fertilisation in school UDDT

Hi Chris,

thanks for your reply and the interesting paper on your experiences...

One question to the following comment:

canaday wrote: Since Moldova is in Europe, the general consensus would be that you cannot do this, since the urine sludge(mostly stuvite) would reportadly plug the holes.


As you say "reportedly" are you aware of any similar attemps in Europe?

Aside from the risk of clogging, one problem in Moldova certainly will be freezing in winter. I see 2 options to solve this:
- Distribution pipes below level of freezing; however this would only allow to reach roots of trees, probably too deep for any other plants.
- Installing a holding tank in winter to store the urine during winter and use it in summer; the whole system tend to be complex then...

After all, I am not sure if the idea really makes sense.

Happy for more experiences and comments!

Cheers, Florian


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  • canaday
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Re: Urine infiltration /subsurface fertilisation in school UDDT

Dear Florian,

Good question. I remember someone from Europe (maybe in the Ecosanres yahoogroup) saying they had tried perforated hoses and that they categorically did not work. (I do not believe there is any mention of perforated hoses in the 1998 or 2004 versions of the Ecological Sanitation book.) Before that, I was already doing it here in the Amazon and knew that it worked, at least in a warm, humid, biodiverse place.

I suspect that some organism eats the struvite here before it builds up enough to plug the holes. Sometimes I see an innocuous little black ant running along the hoses, but it may be a matter of microbes.

I have also learned to not use any connectors or Tees that insert into the hose, as these do get terribly plugged. Each hose has to have a fairly straight run to its perforations.

As I mentioned, I think it is key to have a plastic mesh in the urine funnel to keep sawdust and other cover materials out of the urine hoses a much as possible. I make the funnels from plastic bottles and can easily sew the mesh into place. Without the mesh, one would never know how much sawdust are throwing into the urine diverter.

This is a great thing to work out, since the urine disappears on its own, by gravity and fertilizes the plants we want fertilized, before fermenting and producing odors.

How deep does it freeze? Even if this only works with fruit trees, it would still be spectacular. It would be great to work out an effective, low-maintenance system that works all year. But you could also have the perforated hoses working in the warm months and some other system (as Kent Madin is developing in Mongolia) for freezing months.

Best wishes,
Chris

Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
inodoroseco.blogspot.com
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  • charlesthibodeau2030
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Re: Urine infiltration /subsurface fertilisation in school UDDT

Hello Florian,
I just want to point out three aspects relating to urine management in winter.
1. Here in Eastern Canada we have cold winter (-30 C for one week in January) and the wastewater pipes regulations force to burry the pipe under 2 meters.
2. We also have few constructed wetlands (CW) that treat wastewater from small and rural cities. They work all year long because wastewater flow enters at about 50 cm under the ground level and this is about the level all along the the CW.
3. To prevent urine pipe freezing, I think, like Chris, that mixing with the high volume and sometime hot (shower) of grey water would be an option.
Cheers,
Charles, student in ecological sanitation
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  • Florian
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Re: Urine infiltration /subsurface fertilisation in school UDDT

Hi Chris and Charles,

thanks for your answers!

Luckily it's not as cold as Canada, but Eastern Europe also gets pretty cold in winter, water pipes are laid normally around 1 m below ground.

Good point with the hot water! We have no showers (school toilets) and also not large quantities of water to mix with the urine, but still some warm water for hand-washing, that might help to keep the freezing risk low.

So I see 2 main issues:
1) how to avoid clogging from urine precipitation? Dilution with hand-washing water may help, but perhaps not enough? Would a smaller urine settling tank that allows collecting precipitating struvite etc. work?
2) Due to the deeply buried pipes, urine could only be taken up by tree roots, and in winter it would be entirely lost. So we would have to accept that it is a mix of urine reuse and urine disposal to the groundwater...

Happy about any further comments!


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  • charlesthibodeau2030
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Re: Urine infiltration /subsurface fertilisation in school UDDT

Hello Florian,
To avoid struvite precipitation and clogging I don't really know. But you may try to contact a scientific that I met once that was really nice that works on urine management and potential ways to reuse it: www.eawag.ch/beratung/experten/detail/udertkai/index_EN
To avoid groundwater pollution in winter, maybe can you use constructed wetland for winter only? So about 80% of BOD, at least 50% of P and 50% of N would be trapped and treated. After lets's say 20 years you could reuse the wetland media as fertilizer. I'm not a wetlands specialist but I read a lot about them.
Ciao-ciao
Charles
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Re: Urine infiltration /subsurface fertilisation in school UDDT

Dear Florian,

Chris Canaday suggested some solutions against clogging in his first posting already. I am quite intrigued by his observation of insects and microorganisms feeding on the urine/struvite and keeping the holes clear (what size holes did you use, Chris, for your perforated pipes?).
But is your theory that this only works in tropical conditions and not for European soils and especially not in winter?

My other question is: you briefly mentioned your project in Moldova. How exactly are you involved in that project? Is it the same as project number 194 in our worldwide ecosan project list? (I attach the file - we will soon update it on our website as well, then it will be here and will replace the old version from February:
www.gtz.de/en/themen/umwelt-infrastruktur/wasser/30631.htm


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And maybe it is time that we report about this project in our next ecosan newsletter (for September), how about it? See my other posting here on the forum about the material collection for the next newsletter.

Regards,
Elisabeth

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  • canaday
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Re: Urine infiltration /subsurface fertilisation in school UDDT

Hi Elisabeth,

I make the perforated hoses for distributing urine with the cheapest hose that is available here--black, recycled hose for electrical connections (about $0.12/m). I puncture it every 50 cm and insert a section of a lollipop stick, which are almost always tiny pipes. This makes the holes very uniform (around 2 cm diamter) and professional-looking.

Yes, my theory is that this only works in the Tropics, thanks to biodiversity and relatively constant temperatures. SOMEONE (I think on the EcoSanReg Yahoogroup) said that this has been tried in Europe and it did not work. I also think the plastic meshes are key, to keep sawdust out.

I think it is a great idea to put the hoses however deep is needed to avoid freezing, as long as this is still accessible to trees. The hoses could be surrounded by sand, gravel and/or shredded disposable PET bottles, to avoid plugging by clay. And they could also receive most kinds of greywater (maybe not from laundries, with all the chlorine bleach). People may also feel more comfortable about this kind of food recycling, as it involves passing the nutrients through wooden filters that are meters thick (the tree trunk from the perspective of filtering). The main problem would be if someone has a water well too close.

Best wishes,
Chris

Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
inodoroseco.blogspot.com
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  • christian.rieck
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Re: Urine infiltration /subsurface fertilisation in school UDDT

Dear Florian,

we had a similar set-up in a school in Kenya. The urine from urinals and the 3 cubicles of the teachers UDDT were connected to a 150 liter tank. The handwash basin also drained into that tank. It had a tap for withdrawal (for research of the students, further storage etc. - since we were not sure if there will be an active urine reuse) and an overflow into an underground infiltration area. We had forseen the planting of fruit trees or similiar on top of this area to make use of the nutrients and water. We used a 2 inch PVC pipe, perforated it and placed it in a gravel bed about 1 foot deep. Unfortunately the teachers never really started to use the toilets for specific reasons, but the urinals were well used as well as the handwash basins. So urine and handwash water was always collected. The school was suppose to plant banana trees around the urine infiltration area but failed to do so even after many reminders (lack of ownership and lack of overall training activities).

Have a look at the pictures
www.flickr.com/photos/gtzecosan/sets/721...071/with/6086990592/

I think it is a good set up, however the risk of faecal cross-contamination of the urine makes the withdrawal from the tap abit questionable in terms of health risk.

Cheers
Christian

PS: you could also send an email to the SuSanA working group 5 on food security the link to this discussion for more input. send it to wg5.at.susana.org!

GIZ Uganda
Enhanced Water Security and Sanitation (ENWASS)
Sanitation for Millions
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  • Florian
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Re: Urine infiltration /subsurface fertilisation in school UDDT

Hi all,
thanks for further input to my question. I will visit our team this week, and we will certainly discuss this issue. So I will probably come back with more questions...

Elisabeth:
No it is not the project in your list. I don't know which project exactly is in your list (as no name of implementer) but I assume it is one of the local NGOs we are also cooperating with (WISDOM, SEAM) and the approach is very similar or the same as used in our project.

Our project is called ApaSan (Water Supply and Sanitation Project in Moldova) funded by the Swiss government and alrady active in Moldova since around 2000.
My company, Skat, is responsible for the project since 2008, and I myself am involved only since beginning of this year (so the achievments so far are not mine ;) ).

So far, 12 school toilets based on UDDT have been built and are working rather well (around 4.500 users). However, reuse has only been started this summer, so limited experience with this so far.
Currently our focus is on geting the reuse working (or if it not works, find alternative solutions) and also aim at supporting household sanitation in the project villages.

My colleagues have already prepared a draft susana case study, which I will have to review yet before you'll get it (s.th. that will probably cause me some nostalgia, having done that many times during my time at gtz :) ). Also a newsletter entry is possible of course. You'll here from me on that.


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  • Marijn Zandee
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Re: Urine infiltration /subsurface fertilisation in school UDDT

Florian,

Our experience with struvite is that that the crystals are very small, so I quess that if you use 2 mm holes, as Chris suggests, they will just flow out of the holes and into the soil. My guess is the main trick will be to make sure the holes do not get blocked by soil particles and by sand, dirt, insects, hair and other stuff that ends up in toilets (it is amazing what one finds in urine :-) ). So a filter is definitely needed.

I think you should have a small tank in which the urine and water are mixed before it goes into the ground. It may be an idea to have a plug in the bottom of the mixing tank so that you can drain out all the crystals and other stuff that stays behind in the mixing tank. If the outlet to the drain-pipes is about 10 cm above the bottom that will help trap sand and other larger particles so that they do not go into the lines.

If you need to bury the pipes deep to avoid freezing I do have to wonder how many nutrients will actually be used by plants, even trees. Also you will not be able to check your system. That may be the reason why this option is only for warm places, where the pipes buried very shallow.

rgds

Marijn

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  • deegener
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Re: Urine infiltration /subsurface fertilisation in school UDDT

Hi Florian and all,
I guess the school-UDDTs you mention are the ones that are listed with no. 194 and 195 in the project-list Elisabeth posted. The first ones were constructed by Thierry Umber from SDC in co-operation with wecf. Local partner-NGOs (Wisdom, Ecotox, others followed) made the awareness-raising, training of pupils, teachers and caretakers. When skat was founded they took over the work from SDC and continued to construct further school-toilets with more or less the same design and principle of implementation. As far as I know all of the School-UDDTs in Moldova use 2 chamber GRP-tanks or PE-tanks that allow storage of the urine for min. 6 months (bigger tanks for longer storage are preferable!).
I still think that in Europe collecting the urine in tanks as big as possible is the best solution. If there are problems with the reuse (acceptance, legislative as in Moldova), the urine can still be pumped out and brought to the next treatment-plant if absolutely no other users can be found. We always recommend setting up demo-gardens in the school-yard where at least parts of the urine can be reused. Usually there are also enough trees, ornamental plants, hedges etc. near the schools where (at least part of) the urine can be reused without the risk of polluting the groundwater. I can hardly imagine a gravity-fed infiltration-trench that can distribute several tons of urine per year without infiltration into the GW or killing the plants. Since the plants do not take up nutrients during winter, there should be storage of the urine anyhow.

Against clogging I recommend citric acid or vinegar and proper education of the users.

Greets from Hamburg
stefan
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