Why? We’re in drought, so we don’t have water to flush toilets. The nutrients in shit should be re-used, and that is difficult when we dilute it with loads of water and mix it with god knows what else to be shipped off somewhere to be so-called ‘treated’. Also, flushing toilets mean we are flushing nutrients into receiving water bodies (even with excellent wastewater treatment, we’re still not doing well enough). So flushing is just a stupid idea. More about this in a presentation (pdf, 5MB) I recently gave.
If you don’t know already, I have a dry toilet. I love my dry toilet. It’s indoors, I’m affluent, privileged. This is not about toilets for poor people. This is about dry toilets for everyone.
But, many people don’t like the idea of looking at their shit, so we’re trying to get the experience of the white ceramic sparkly-clean ‘flush and forget’ ‘out of sigh(t) out of mind’ toilet, with the cost-saving benefits and environment and resource recovery goodness of dry toilets. I think currently the foam flush may be our best bet.
NOTE: When I start talking to people, lots of people have lots of ideas, but invariably, these are about the user interface. I don’t care about the user interface – that is whatever you want it to be (except copious amounts of water). The colour, ceramic or plastic, sit or squat, wipe or wash, lid or hole, I don’t care. I am concerned about collecting and storing it for beneficiating later. Don’t give me your fancy ideas at the user interface unless you’ve thought through how this affects the process downstream.
What do we need the foam flush to do? (apart from the usual dignity, hygiene, yadda yadda). This really comes down to what is in the foam to make it do its job:
- Act as a lubricant.
Unlike a standard issue dry toilet that drops your nutritious product straight down, to sit there in the darkness staring back at you (apparently), this goes down an angle, to out-of-sight land. So the lubricant needs to be lubricating. No getting stuck or smear marks.
- Smell nice.
Not just like nothing, or slightly earthy, but seriously amazingly nice (ala PooPourri – I love this product! (doesn’t work in my dry toilet though))
- Contribute to the bioprocess.
Or at the least don’t impede it. This means: No bleach. Probably needs to be a neutral-ish pH (no actual soap, or acid). If it has the bugs that work well with poo, that would be epic – an inoculum, like the yeast that makes your beer, the seed that grows your tree… (see circular economy, resource recovery)
Overall, I keep coming back to giraffe spit. Or, you know, whatever lubricates our assholes (biomimicry: ‘how does nature move shit?’), but giraffe spit seems to be more PC.
Other things that may help:
- Urine diversion is important and a no-regret measure. For now, pee in the garden.
- A trap door jobbie that works with the lid to guarantee no smells coming back.
- A hydrophobic layer on the tube that helps or replaces the lubricant. Like the no-dirt layers on car windscreens, for example.
Some links that show foam flush constellations (yes, that’s a sortofa pun)
The short and sweet by treehugger.
Clivus Multrum composting toilets – according to this site, with images, the foam flush toilet eliminates the ‘dark opening’ of the waterless toilet. For some reason it ‘requires both a water and electric connection, and costs more’. I don’t see this as a real requirement. From this website:
The New England site has even more. Their pics remind me that I’m not all that keen on trying to imitate the standard shape and colour of a toilet – how boring! So I might not know exactly how to get this into mass production (nor do I care). But, colleagues at Isidima may be well placed, see for example their arumloo (still a flushing solution though currently)
This post by the Green Building Alliance (GBA) which reminds me to state clearly that after the user interface and storage bits, there is the collection and transport bits. I do not expect users to deal directly with their shit. This is also not a pit latrine solution, it needs to be above ground and easily collected – consider the weekly solid waste/trash collection idea.
Also, the trapdoor future idea is a way to deal with what the ‘S-bend’ tried to do – avoid odour. With a well functioning composting process, odour is not a problem, and instead of trying to create all sorts of fail-safes to deal with odour, I would rather have the foam solution be something that contributes to a more robust well functioning process.