We had a visitor to UC, yesterday, Idabelle, who is working on a distance learning course in composting toilets taken "at" Prescott College. Welcome, Idabelle.
Aimee and I built tried or three ad-hoc composting toilets at the Bale House before we came up with one that met my criteria of recycling human manure or humanure, while also meeting Aimee's criteria of looking and acting like a "proper" toilet. Most American folks, faced with this problem, buy an Ecolet or SunMar or similar model, a self-contained commercial compost toilet system. But these are expensive, generally costing upwards of $1,200. If we had an extra $1,200, we would have spent it on extra solar panels, not on sewage treatment. What are the alternative choices? Our Quaker friend Lucinda, who is in her eighties, still uses a bag of sawdust and a five gallon bucket. Lots of Unity College students live in cabins with traditional outhouses. But these can be a bit rugged, especially for visitors "from away."
We settled on a hybrid system. We used a holding tank in the crawl space, situated directly below an RV toilet that cost around $170. The low flush RV toilet created sewage too wet and lacking in organic matter to compost by itself, and so you emptied the holding tank (carefully!) every week onto sufficient other compost material ("greens and browns," for those of you who know how to layer compost), all of which was kept in an outside heap. The moisture, in Maine summers, was enough to cook the pile quickly, but not too much. In spring and winter, when things were wet, or frozen, we covered the pile with a scrap of plastic. We used a lot of straw (for a brown), and that helped with aeration and consistency. After we produced finished compost, or close to finished, we turned it, re-piled it, and left it completely alone for a further year. We thus used two piles, one in-use, one waiting out its year, piles we made with poles sticker-stacked, pretty much as was done by the Nearings at the Good Life Center and described in their books.
We never got to the point where we could have actually used this material -- we moved into the new house first, but the residents of the Bale House continue the system.
What surprised me the most about this system was how little waste was actually produced once the compost was made. Just a few buckets a year, a couple-three wheelbarrow loads, of finished compost were left. Most sewage is water. The other thing that I got out of this was that few of us ever really bother to think about sewage. We take flushing the toilet for granted. Emptying that holding tank for three years cured me of that.
Composting sewage is definitely an important solution to a couple of big problems, that of water quality and water conservation (although not so much the latter in Maine -- we have plenty of water, sometimes too much), and if we we could keep household chemicals out of it, then municipal sewage sludge and the sewage-made compost that is produced by tertiary waste water treatment facilities, would be a lot more wholesome agricultural or horticultural input than it is now. I recommend working with sewage and humanure on a small scale for anyone who wants to understand sewage disposal at any scale.
Idabelle is checking in if anyone has any information for her on compost toilets.