Comparison of incinerating toilets
When I started the dry toilet journey I was only aware of one incinerating toilet brand. Separett was synonymous with ‘the creme de la creme of dry toilets’ – incinerating or otherwise. After visiting Mikael and his team I think my loyalty to Separett is rock solid, but it turns out there are other incinerating toilet companies out there. I have a Separett Villa 9000 to test out, but I think the designs need to change a lot for large scale urban use – read on.
Testfakta, an independent testing and research company specialising in laboratory tests and the assessment of consumer products, did a comparative study of four incinerating toilets in 2014 and again in 2018 – comparing the top end products of the companies: Ecotech (Cinderella Comfort), Separett (Separett Flame 8000), Fusa (Toamoa), and Incinolet (Incinolet TR Deluxe 1800). Some details on their website, and here and here. I didn’t read all of this, because I think these toilets are not the right designs, so I got bored, but it was interesting to see that there are multiple companies in the field.
Are incinerating toilets the way to go?
Mikael explained to me that when his father started this company, it was not concerned with environmental protection or resource recovery. It was simply about providing a solution for holiday toilets – the first world equivalent of toilets for poor people, one could say. But times are changing, and the race is on for incinerating toilet companies to create convenient ecological toilet solutions, that respect both human needs and desires and environmental requirements.
This is trickier than expected. I think we tolerate ‘roughing it’ in holiday homes, poor energy inefficiency and possibly a bit of a smell, but none of that is acceptable for everyday use. Currently I think there are only two approaches to dry toilets: either make it all go away, like the incinerating toilet and many of the ‘reinvent the toilet’ designs, or keep it all inside and together to ‘return to nature’ somehow. Both of these are problematic for large scale adoption, in my opinion.
The make it all go away approach sounds great, but needing to incinerate all that liquid, mostly from the urine, takes a lot of juice. This is why the incinerating toilets have power outputs comparative to stoves (around 1600 to 2000 Watts) and heat up to about 600 degrees Celcius. A good rule of thumb is planning for about 0.5 kg faeces per person per day, and around 1.5L of urine, per person, per day. It’s the faeces that stink and that is a health hazard, so spending all that energy on the urine seems silly.
Urine diversion is not popular – surprising until you try it.
This was the biggest and most surprising learning curve for me – I never thought urine diversion was so controversial!
When I started using a dry toilet it all went down the same hole, and it took me about a week to realise this was a dumb idea. Within a week I had 1.5L * 7 = about 10L of urine, mixed with another, say, 3kg of faeces making a bucket full of heavy, sloshy, stinky mess. And at the current rate I was going to have to deal with this mess weekly. Not cool. So for me urine diversion is a no-brainer. With urine diversion I have a dry, not stinky bucket that takes more than a month to fill up, and is less heavy to carry around. Win. Separately I have a smaller urine bucket that goes into the garden every few days.
Urine is also very valuable, it has lots of nutrients, and no pathogens. Sure, it’s only sterile upon exit and only from healthy individuals, and it can get stinky after standing around unattended, but it is much easier to deal with than faeces and my colleague and friend Dyllon Randall is doing amazing research on it – the business model for urine collection and beneficiation is proven, we really want to get our hands on your urine!
So it was really surprising to hear a general dislike of urine diversion toilets. Some people in my business network flatly refuse to make urine diversion dry toilets, saying people just refuse to use them and they’re a pain to service, and urine diversion flush toilets struggle with cross-contamination. Poo in the pee section, for example. Personally I never get the aim right and my urine ends up going down the poo hole anyway. And it looks weird, I’d like a more pleasant experience on the bog, to be honest. I’m also not convinced any men really like sitting down to pee.
Then there is the humanure movement who believe strongly that pee and poo need to go together to feed the soil. Any arguments about the high maintenance sloshy, stinky mess and the potential to contaminate the soil and groundwater with now pathogen-laden high nutrient liquids seem to fall on deaf ears. Yes, we need to return the nutrients to the soil, but we need to be careful about it and do it responsibly and appropriately for the high density impacted environments we live in. Also, not everyone wants to deal with their own shit. So this off-grid thinking is limited (I am not a fan of ‘off-grid’. Distributed, yes.)
So I was stumped: why was I fine with urine diversion if no one else seemed to get it? The answer is because I don’t have a ‘urine diversion adaptation’, I use an entirely different toilet for peeing. I have two toilets! One only for peeing (ok, it’s actually just a little 8L bucket with lid that I squat over. I’d like to say I have something fancier but this works so well I can’t see a way to improve it), and one for everything else – the bright red box (pee is fine to go in here too, when you’re doing a dump + pee, for example). By the way, I squat for peeing (solving problems related to sitting), and poo in a custom toilet that allows me to sit and daydream while my knees are high enough to still make for healthy bowel movements. #squattypotty
My perfect toilet is two toilets.
This made me conclude that toilets as we know them are badly designed altogether. I think we need a separate design for peeing – and probably separate designs for those who want to sit/squat and those who want to stand (I think standing urinals are OK as they are from the user experience perspective, right?) – and one for pooing that gets the squat angle right.
Container based sanitation (CBS): I don’t consider composting toilets as an option, because like pit latrines, even if they take longer to fill up, emptying them out is a proper mission. Fully containerised (and the ideal size here seem to converge to 20L buckets with sealing lids for transport) is non-negotiable – a person needs to be able to manage the toilet and its contents on their own. Ideally the toilets should be able to be installed with minimum modification of walls or the floor – not least because then you can move it around as you please, for cleaning or interior design changes. Or simply for storage if space is an issue. Perhaps air vents will always be needed.
Burn the poop: While I agree that faeces contributes valuable organic matter to the soil, the pathogen load worries me. So I think poop in the urban context should be incinerated. Biochar production inside the toilet, on-site would be great, and I think should be doable, and more energy efficient than the current 600 degrees job. Then separate to this something that collects the urine, and working with the current logistics challenges, have a system that precipitate the nutrients out and letting the remaining liquid go to the sewer, or seep away into the soil. The precipitated nutrients can then be collected by, say, a fertiliser or bioeconomy-related company. This is a distributed approach and needs more research, sure, but Dyllon is gaining strides, fast. My urine goes to the garden, unprocessed, and will continue to do so for as long as I can see. But I have a garden, so that’s privileged. I also think urine is great for some guerrilla urban greening even for those without gardens, but diluted 1 in 10. Undiluted urine stinks, and once the Cape Town drought is over I’ll dilute mine more as well.
There’s another aspect related to covering material – sawdust or plant material or compost or soil or ash. This could link to the urban greening that creates biomass, but I think for the urban context the incineration option will remove the need for covering material at large.
“High design with a small footprint.” – liveklein.com
The bottom line is toilets are domestic appliances, like fridges. We should be able to choose the design and consider them fashionable in the same way. I recently came across this stunning LiveKlein tiny house from Danish designer Bjarke Ingels and colleagues. I want one, so bad. Their tagline of “High design with a small footprint” is so appropriate for toilets. This is the end game.