I will be setting up a sawdust toilet later this year, and haven't come to a conclusion about whether or not to separate urine. I'm re-reading the Humanure Handbook, and Jenkins is adamant that urine should be included. However I know there are plenty of permies who are adamant about separation. It seems the main arguments for combining are that the compost needs the moisture and the nitrogen. And the main arguments against are that it gets too wet and sloppy and smelly. So who's right?
For a simple system it should be easy to make changes if something isn't working. And obviously people have had success with both methods, so I'm just interested in hearing more details and stories. What did you start with? If it didn't work, what have you tried differently to make it work? Has anyone tried keeping urine out of the bucket, but then adding it back to the compost pile separately? Why are you convinced that your system is the right way?
I haven't seen a thread devoted to this, although there are lots of snippets in other conversations. If one exists, my apologies.
it depends. i started a thread on small scale poop processing... there s some info on separation and poop-treatment.
thing with jenkins is: you ll need some quantities of stuff and cover material. the hot composting should be safe (pathogen-reduction). but will it work when you just use the toilet a few times a week?
pathogen reduction is good. but. i remember in a podcast paul did, that the lady (author of some books on that topic) said like: i just compost the poop 3 months and that s it.
some pathogens are destroyed by a short time of (not-hot) composting. the other pathogen you ll probably never find in your toilet, unless you ll have people come over that carry certain diseases or worms.
for me, the main advantage of seperation is, that i can use the urine as fertilizer. i plan to lead a house through the wall directly into a watering can.
Thanks Tobias, I'll take another look at your thread too. I wonder what the required "production rate" is for hot composting. We'll be two people living there full time, but no kids planned.
Whatever I do, it will need to convert my girlfriend, so I definitely don't want heavy, smelly, messy buckets. I'll probably end up separating for the most part, adding a few buckets at a time to a two-bin composting station. It is an arid location (western Colorado), so I am concerned the pile will be too dry to compost at all. I'll have a bucket rinse station and will dump the rinse water on the pile. Maybe it will still get hot. Either way it will take us long enough to fill a bin that it should still get well over a year of sit time.
We do the Jenkins method of just combining poop and pee. Over time, we've got a few consistent, free sources of carbon (straw and wood shavings)-- each with their own advantages and disadvantages.
If I didn't have three kids + 2 adults using the toilet, I might be more open to separating out pee to use directly on our trees. My sons do pee quite a bit outdoors. We could use the nitrogen in the short term, which I think is the main advantage of separating out pee, which doesn't need to be composted. As it is, that would just be too complicated.
I've found combining pee and poop with a carbon source makes very good compost, pretty quickly. Our first years' compost is rich and black just 3 months after we started a new pile-- if I needed compost right now, I wouldn't hesitate to use it for trees. I guess for me the advantage is that I'm creating rich, biologically active organic material when I combine, whereas pee added directly to plants in my climate (mediterranean, with sandy soil) would be more like adding inorganic fertilizer: effective in the short term but not necessarily building the soil directly. That's my theory, at least?
If concerned about weight of the bucket, I'd recommend hay/straw as a cover material, as the bucket fills up fast and is not as heavy. Grass clippings or wood shavings have advantages because I don't have to cut them up, and they last longer-- I don't have to keep going and getting a new bucket of shavings-- but it does make the bucket heavier and I struggle to get my small kids to cover their poop properly (it's easier with large pieces of straw).
sortof-almost-off-grid in South Africa: www.concretegardener.com
two persons full time is more than enough. could you shade your pile? maybe have some solid walls and/or throw some tarp over to keep moisture (but also would slow composting process cause of reduced oxygen).
hey jo ...
soil building with urine: it works when you have ebough browns in the soil. or to feed potted plants. or as foliar feed (please research that, i never tried that).
to cut straw/hay: i ve seen people throw it on the floor and suck it with the kind of vacuum cleaner for leaves that shred the stuff and press it into a bag.
I used to have a commercial composting toilet. A big part of their design is being able to capture the nitrogen while drying out the excess water. Vent pipe, fan, some even have heaters. If I built a bucket or barrel toilet, it would have a turbine roof vent mounted to power the exhaust pipe plus some solar gain if possible to help dry it out.
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Well in the end it probably won't be a bucket system a la Jenkins. I spoke with the county septic inspector who is open to composting toilets. But my options are to buy an off the shelf unit or build a Sunny John. So I think I'll actually end up with something pretty close to what R Scott describes. Probably a detached raised structure with two built in bins, solar heat, and solar/wind powered venting. How much do you really want the stuff to dry out? Just the excess liquid that drains off? If it's like other composting I imagine you still want plenty of moisture in the material.
Instead of barrels or concrete vaults, I like the idea of having the poo drop into bins lined with straw bales - for insulation, to give the edges of the pile some extra oxygen, and maybe to soak up some of the extra liquid as well. I like straw bale compost bins in general, but it seems to be even more appropriate for humanure.
Does anyone know where to find Sunny John plans, or have the general schematic for it? Looks like sunnyjohn.com is defunct and there's not that much detailed info on the web.
I separate the pee mostly because of the odor but I also want it dry.
I plan to build a passive solar oven large enough to cook poop in.
It will have enough room for 4 to 10 5gal. black metal buckets.
It will have a large black pipe for humidity & heat ventilation.
Basically it will be a large black box with a glass cover over it.
I use a fine cedar sawdust & I keep my paper separated out too.
I also want to keep all the pee out so I don't have to cook it out later.
The pee can be added to the grey water and used in the garden irrigation.