Feculence

In honour of the newest sponsor of the Mission:Emission expedition, Separett (www.separett.com) I am writing this blog whilst perched on the toilet.

Ever since reading the Humanure Handbook (www.humanurehandbook.com) I've been really interested in the concept of waterless toilets. Historically it was Thomas Crapper that came up with the idea of a water based flushing toilet during the Victorian era, and thanks to the British Empire it spread around the world. But before that we were quite happily crapping into dry toilets.

There's a massive amount of water used to flush our faeces down the drain, and like so many waste products excrement can be a useful resource for making compost, or as a source of sustainable energy when put through biodigester.

For a while I even joined a yahoo group about composting toilets. It's amazing how much traffic there was on the group, and the powerful emotional attachments people form with their composting toilets.

Put simply, if you subject your dung to a combination of warmth and aeration for about 12 months, all the pathogens in it die, and then you can use it to fertilise food crops. If you can't wait that long, then you can use it fertilise plants that wont re-enter the food chain after a few months.

The Separett toilet we'll be fitting to the bus works by separating the solids from liquids, thanks to a cleverly designed seat. It's then much easier to deal with each separately.

The urine is sterile and can be disposed of by diluting and spraying on soil. Whereas the solid waste (I love how many euphemisms there are for faecal matter) is dried by a continuous stream of air, which also takes the smell away.

Apparently composting toilets don't smell! And in my limited experience of them they really don't. I had a considerable movement at last years annual meeting of the www.vegetableoildiesel.co.uk forum, near Beaconsfield, and subsequently spent quite a long time examining the longdrop design of that one.

Certainly the smell was better than traditional cassette or chemical toilets used in campers, which reek of the blue chemical they use to break down the excreta mix.

Building one in a vehicle is more of a challenge because of the space they take up. There are plenty of people that have put them in canal boats, were the "liquid waste" can be pumped overboard, but they are a relatively rare thing in camper vehicles.

In a true composting toilet you add a bit of carbon after each use. Something like shredded paper or sawdust for instance. This prevents the nitrogen in the caca reacting to form ammonia which smells, and it also allows the pile to trap oxygen.

The Separett system is slightly different, in that the stool dried rather than composted in the toilet, and when it's full you dump the contents into a compost heap, or into a sewage system. By the time you empty it, the contents are predominantly toilet paper, as the bio-matter dramatically decreases in volume as it dries.

I'll need to install a grey water tank for the waste liquid from the sink and shower, and mix the peepee in there, but in practice we'll probably only use it for number ones if we're also doing a number two too.

Now I have to perch the laptop on the sink while I clean up. Excuse me.