permaculture

[John Schinnerer <john@eco-living.net>]

Aloha,

> have anybody of you made a 'do it yourself ' compost toilet for use
> inside the house? we builded a bio cleaner for greywater cleanong
> last year, and we use it now only for the washing mashine waste
> water. now we want to redirect all the greywater to the cleaner and
> we need to separate the toilet from the sewage, that's why the
> compost toilet. we are freaks and want to use recycled materials or
> find cheap materials. any expirience with this, any schemes of such
> toilet, expirience with composting of feces with worms ?

I have heard of successful worm-based composting toilets.
No direct experience myself.

There's always the humanure bucket toilet of course.

Rather high-maintenance however, and probably the most scary to guests 
and others not used to anything but a flush toilet.

I have been pondering a design for a simplified in-house composter, to 
potentially replace a SunMar commercial unit a friend has.
This would be essentially a two-vault composter, no moving parts, once a 
chamber is full it is closed and allowed to rest for an adequate time to 
complete composting (a year would be typical).

Main issue is getting enough volume in each chamber (making the unit big 
enough) to last e.g. a year, so that one chamber can sit a year while 
the other fills.

If you can build the toilet room around the toilet, or it's a separate 
structure, that's no problem (see for example 
http://www.eco-living.net/projects/ovaloffice/ ).

If you are trying to fit it into an existing space in a typically small 
bathroom, it's more of a challenge.
I haven't done the volume calcs yet for a small household unit.  Would 
depend on how many people using it on average, plus some consideration 
of short-term higher usage (parties, gatherings, company, etc.).

For building the vaults simply and quickly I am thinking of using cement 
board, framed/stiffened on the outside by strategically placed wood or 
metal (outside framing could be scrap/salvage materials).
Hand-built ferrocement would work too, but would be messier and 
potentially awkward to build in a confined space, and more 
labor/time-intensive than buying sheets of cement board.
Either way the idea is to have little or no organic/decomposable 
material in contact with the composting contents.
Venting etc. would be as for any typical two-vault composter.
Compost removal door would ideally be through an outside wall, where 
structure and climate allow.

Chambers need a fair bit of height to them relative to other dimensions 
- broad low chambers are *not* recommended - because the humanure tends 
to pile up in a tall cone under the deposition point (the seat :-). 
That can be periodically knocked down/spread out, of course, but that 
adds maintenance overhead.

If there's a basement or crawl space below the location, vertical 
chamber volume could be put there.  If not, the whole volume, including 
adequate vertical, has to be in the existing space.
Would definitely be a 'throne' one steps up to sit on...

John S.

--

John Schinnerer - MA, Whole Systems Design
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