Mix water with urine in straw compost?

  • Frankle
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Mix water with urine in straw compost?

I'm building an offgrid cabin. I have a urine diverting compost toilet, and a urinal. I plan to run the urine into a straw filled barrel in the ground, with holes in the bottom feeding into a soakaway. I can also run the waste from the (very small) wash hand basin into the same waste pipe, as I think it might help to keep the waste pipe clean and clear. The run is about 7m long. I don't think there will be much soapy water going in there. My question is this: will water (with some soap/toothpaste) be unhelpful for the straw composter?
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Re: Mix water with urine in straw compost

Hi,
When I hear urine and straw, I think of this forum post by Florian from 2013:

forum.susana.org/forum/categories/170-pu...france-germany-#4280

See:
www.uritonnoir.com/
www.guardian.co.uk/artanddesign/architec...ale-urinal-festivals
www.spiegel.de/wissenschaft/mensch/apres...onnoir-a-895235.html



Anyhow, in the meantime you have probably tried it out. Did it work?
Over time you might get a build-up of struvite in your pipe which could lead to blockages. Or you might find some slimy struvite build-up with is easy to clear from your pipe.

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  • cecile
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Re: Mix water with urine in straw compost

With regards to Florian's post and the "uritonnoir" ("urine barrel").
As far as I remember I read very negative feed back about the "uritonnoir" which was used in a festival. It seems it ended up in urine leaks and smelly ponds all over the place.
It does not mean that the system is not good in itself, but the use was probably to heavy compared to the capacity of absorption of the straw bale and it also seems there was no diversion ditch.

I experienced the use of a straw filter in my house when I lived in France. The bucket was placed between the urine and grey water exhaust pipe and the planted filter. It consisted in a burried bucket with drainage holes at the bottom and filled with straw. Grey water and urine arrive in the bucket by gravity and then are discharged in the filter situated about 10 meters away. The purpose of the straw filter is to collect solids that may end up in the grey water and grease. I renewed the straw every 3 months.

What I can tell you is that the content never turned into a compost. However urine was significanlty diluted and the retention time was probably very short (which is different in your case).

I think it is not surprising because : 1) straw is one of the most resistant material (it hardly rots) 2) there is very little organic matter and you still need a good N/C balance to make compost...
But then I can't draw general conclusions with one trial only. I have also come across videos on tube where some people do pour urine in straw balls for composting purposes. You might want to be in touch with them directly.

Regards,

Cécile

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  • Frankle
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Re: Mix water with urine in straw compost

The theory I've been reading about says that (I know nothing about organic chemistry) urine has lots of nitrogen, and straw has lots of carbon. Together, it's a perfect recipe for producing good compost. Also, it says that it won't smell because the bacteria will have a 'balanced diet' of carbon and nitrogen, and won't have to give off ammonia, (the bacteria's way of reducing excess nitrogen)
My concern is that by adding water, I will be diluting the process, or possibly washing the straw and interrupting the composting-making process. I guess it depends on how much water goes in there.
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  • Frankle
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Re: Mix water with urine in straw compost

Thanks for your reply Cecile, I think you're right - the main problems with a heavy usage "urittonnoir" would be that there is nowhere for the excess liquid to go. I won't have that problem, firstly because there is a soakaway under the barrel, and secondly, because it won't be used that much.
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  • cecile
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Re: Mix water with urine in straw compost

Dear Frankle,

You are absolutely right about N in urine + C in the straw, but I would imagine you also need micro organisms (humus? earth?) and more easily degradable carbon?
But this being said I am not a chemist or biologist either.
Please document your experience, take pictures and let us know how it works whether is succeeds or fails. I find this is quite interesting to find different ways of managing urine.
Cécile

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  • Frankle
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Re: Mix water with urine in straw compost

Dear Cecile,

I have just put miscanthus into the urine composter. I read that it composts very easily, so we'll see. It will be some time before it gets tested as such, because it's serving an off grid cabin in my back garden, and we're not quite ready for guests yet.
I will post any results here!

Thanks for your interest.

Frank.
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  • toiletrevolution
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Re: Mix water with urine in straw compost

Hemp stalk is also a great material for composting. Some of our customers use it with good results. Here is a supplier www.omlet.ie/shop/chicken_keeping/poultr...iose_bedding_-_20kg/ .

Benefit is that it's soft so it breaks down quite easily and it store 4 times more moisture than wood shavings which might be handy in addition to the straw.Cheers
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