Hot Poop on Composting Toilets: Separett
by Lloyd Alter, Toronto on 04. 3.07
As John Laumer noted earlier, there is a lot of useful stuff in pee, but we dilute it with gallons of water, send it down big pipes mixed with everything else, and suddenly we have monstrous networks of waste piping, sewage treatment plants and water shortages feeding it all. Yet as Carol Steinfeld wrote in Liquid Gold, urine can be used "to grow food and landscapes, while protecting the environment, saving its users the cost of fertilizer, and reconnecting people to the land and the nutrient cycles that sustain them."
That's why we were so intrigued by the Swedish Separett Composting toilet that we saw at the Cottage Life Show. It separates out the urine, which can be put to use in the garden or drained to a leaching pit, and the poop, which is kept within the toilet for composting. Because the urine is removed, the volume is much smaller, and the mixture does not ferment, creating that familiar smell of overused outhouses.
Sitting on the seat activates a trap door and rotates the container below so that it fills evenly, and electric fans exhaust any smells to the outdoors, and aids in drying of the poop. (12V solar powered version available).
After three to six weeks, one opens the lid and removes the container, adds some soil, carries it out to the back forty and lets it sit for six months, in order to inactivate all human pathogens. Then it can be used as compost. (so you are going to need about six containers, or use the compostable waste bag as a liner)
We were a bit suspicious of that last aspect of it, lining up containers in the garden, but they have been doing this in Sweden since 1976 and have sold over 200,000 units. It has UL and CSA approvals, so it has been tested and deemed safe. However we think that perhaps this might not be the best unit for urban use of composting toilets, unless you have a very big backyard or balcony.
An optional 50 litre ejektortank can be used to gather the urine and dilute it 8-1 with water; connect a hose and spray it around the garden. Now available in Canada via ::Separett.ca and in the States, from ::Ecovita.
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I have some trepidation about using these in a setting where tropical disease, parasites in particular, are a major health risk. Also would be concerned about dung beetles and other detritivores not common in Sweden, spreading the goodies around.
Not to be too flippant, but it would be interesting to find out how the toilet differentiates urine from diarrhea.
This does seem to be a promising notion. This would be especially exciting as a way of diverting raw sewage from storm drain systems.
What about toilet paper?
Separett, cleans up the world...
Nobel prize next!
I want one..
Keep in mind that in most, if not all, US States and Canadian Provinces, you cannot legally spray urine (even if diluted) on your garden. It's not allowed.
As stated so many other times on Treehugger, urine is usually pathogen free.
Urine-diverting toilets keep urine separate via a drain cast into the fron the bowl. Urine naturally expresses forward or men have to aim carefully (or use a urinal).
Feces, the more significant pathogen source, process faster aerobically, so keeping the urine separate allows this to decompose faster and the pathogens to be destroyed.
There is a large body of research about this in Sweden, Germany, and China.
Urine can be discharged to a leachfield or contained for 1 to 6 months and used topically. See http://www.liquidgoldbook.com
A interesting idea for cabins and homes off the grid, but isn't soil disruption an issue as well? Most places I have lived in the US always have critter issues whenever burying anything organic. So you end up having to dig pretty deep.
For these low or no-water systems I am a little more partial to the vacuum systems... for convenience. But vacuum systems are flawed because all piping will eventually become saturated and start to smell, which is a pretty common issue in boats and RV's.
Soil disruption is not an issue if the waste has been composted in the container for 6 months as described above, because the material you are burying is already well on the way to becoming pretty ordinary inoffensive compost, of little interest to critters.
Paper goes into the composting container, and actually helps the process by aerating the contents.
This is the best way to handle human waste. However the seat should be 20 dollars max,