I am not an expert, but some comments:
- The poo does not smell very much if the pee is separated from it.
- Saw-dust takes the smell away within seconds, but I think that conferious wood, pine and spruce, is better, but I do not know how these woods with resin effects the end-product, the compost?
- I saw myself mainly birch, but has never had an opportunity to test birch saw-dust alone.
- In our country we will have a law about water-toilets 2014. Now the firms are selling all kind of gadgets and Gizmos that has got the approval. They cost between 7.000 - 14.000 € with the work done. Never mind my feelings about this kind of money thrown at the poo.
I have thought it could be solved like this:
- Making a 'pool' that is made of stones and lime. 70 cm high, 1,4 meter broad and the length of 3 - 4 meter. The pool does not leak if it is made properly.
- Put on the bottom all kind of scrapwood, saw-dust etc.
- In spring-time emptying the buckets (that are frozen in the winter and do not smell), into the basin/pool. Need a lot of buckets, but that will not be a problem as we have some painting industry that gives very big "buckets" for free. They are plastic and clean.
- When the basin is filled with poo that has a lot of saw-dust in it, then put there leaves and whatever is at hand. After that put some 10 - 15 cm of earth and the roses growing.
There is one problem: The mixture needs oxygen. I have thought I will construct a small windmill, with a pump, (found in old cars), and a hose that I have put on the bottom of tha basin.
The next summer I need to make a new basin, and maybe a third one, but then I have the garden levelled up 70 cm when I am old and can't bend myself so well.
And in my eyes, natural stone-walls are nice-looking too. The problem is with the lime; it is not so ecological as the industry use a lot of energy when they make it, but not so much as the cement industry use.
- I have to think a little bit more about this. Maybe I should make the masonry-work on the solid rock, and thus I can see if the basin is leaking?
- Then there is the question about getting rid of water before winter-time as the bottom part of the basin can break, if there is much water and the ice will damage my masonry. Probably I have to make a tap on the bottom, so that I can tap out the water?
- I like the thought of worms as well, but I think that they can't survive, if they can't go deep into the earth when the winter is coming? Or how do they live through winter in minus 20 C?