Toilette eu de Rocket?

Partially out of mere curiosity, partly out of, 'hmm - this info could be good to have, some day...', especially if I need to move into a tiny home, decide to add a tiny guest house, or maybe even convert a box truck into an RV. Plumbing is expensive to add to a new build, or pretty much anything. Fixing plumbing faux pas can be not only expensive, but labor intensive, taking into consideration the potential water damage, mold, etc. So, other than a willow feeder, or other form of composting toilet, which can be space hogs, and/ or require going outdoors in the middle of the night, in bad weather, even if you're horribly sick, none of which are ever going to be an option, for me - I came to incinerator toilets. Buuuut, they have their drawbacks, too! They are PRICEY. They use paper liners. Annual cost* of use can be in excess of $500 - for 1 toilet and only 2 people. A solar powered one is even more expensive, and kinda highly dependent on... well - the sun. No sun, no cremation of defacation.

Then, I got to thinking about rocket stoves, and if there was a rockety-type poop-burner. I don't know if it is even feasible - but, I don't see any reason it wouldn't be... somehow. Ideas? Thoughts? This is - at least for now - just hypothetical. I think. Maybe...


*https://www.septictankhub.com/blog/incinerating-toilets/

Hey Carla;
You're thinking outside the box again... always a good idea.

This would be a pretty hard one to implement.
To start, somehow pee would need to be diverted; where would it go?
Having a reliable way for poop to get into the burn tunnel, but then close off when the fire is roaring.
But the biggest problem is... most of the time your rmh is not lit... where would the poops wait??? Wouldn't they be poopy smelling?

Perhaps instead of a Rocket burner, a homemade incinerator with a weed burner?  
BUT... Might burn the little home down if run by a novice...

Well, what if you were to dry the poop in the sun (or a designated rocket dehydrator) and then turn it into lumps to burn as fuel? They do burn cowdung in places without a lot of trees—rural India, Africa, Tibet.

Turn it into char.

Humanure char is a high-ash, high pH, product that contains lots of mineral content.

You can even begin the gasification with wet poop, but you'll get better efficiency and ease if you mix it with a dry carbonaceous media like wood dust to cut down on moisture.

The data indicates that poop+wood creates better char for soil than poop or wood alone because the wood improves the structure of the char for soil improvement and absorbs the nitrogen and phosphorous(amongst other things) that the poop provides and locks it into it's carbon skeleton to slowly release into the soil. Wood chips are better than wood dust for structure, so a blend to control moisture and add structure would, maybe, be ideal.

There is a design for an indoor willow feeder. It's implemented in Cooper Cabin here at Wheaton Labs.

Here's a peek:

https://permies.com/wiki/357815/Indoor-Willow-Feeder-plans-Cooper

M Ljin wrote:Well, what if you were to dry the poop in the sun (or a designated rocket dehydrator) and then turn it into lumps to burn as fuel? They do burn cowdung in places without a lot of trees—rural India, Africa, Tibet.

M's thinking along the same lines, (but much more clearly) than me. Particularly her comment about the rocket dehydrator concept.

Yes, a urine diverter of some sort would be essential.

Most of what makes poop 'stink', I would guess, would be moist volatile organic compounds. It seems to me that wet dog poop stinks, but sun-dried dry dog poop likely doesn't.

Once the poop is dry, (which kills most of the nasty microbes), you would still need to dispose of the results. Dog poop sort of turns into poop tootsie rolls from what I've observed, but I've never dealt with them, so I have no idea how easily they break apart. I have even less idea of the structural integrity of human dehydrated poop.  My thought would be to wrap a line of poop up in newspaper like a long version of a Christmas Cracker. Then you could feed that into a rocket stove or possibly a rocket mass heater. I think the shape of a rocket mass heater feed tube wouldn't be as convenient as something more like a batch box.

Experimentation may result in a decision that any version of this would be totally impractical, but I think it is worth thinking about. There are a lot of people out there for whom composting #2 isn't an option. Figuring out some cost effective, low energy options would be great.

Reading all your ideas gives me ideas! Many (most?) camping &/or composting toilets rely rather heavily on wood shavings or sawdust sprinkled over the poop. Most of those don't even divert the urine, because the wood absorbs the moisture from both the feces & urine. If that could be part of the rocket toilet system, it would eliminate the need to separate solids from liquids - a good thing, considering most of us women can't always separate those functions, and I, for one, am lazy enough to truly not *want* to deal with arranging or cleaning up after such a separater. Nope. Too much like work. Icky work.

The time factor & moving heavy bins, are other issues I have with the willow feeder. I'm getting older faster than I like to admit, already disabled, and by the time any of this could come to pass, I may well be living alone, so that kind of heavy lifting isn't an option - nor are stairs. However... much of the concept & design could be utilized, I think. A somewhat smaller can, outdoor access to the can, with the rocket (kiln?) near the access? No....  But, it feels like I'm onto something...

How hot does the burn get in a rocket? Not a rmh, but a simple rh? Something along the lines of the Liberator? If the (possibly at least partially dehydrated) poop/ sawdust were helped along with a few sticks... Maybe then, it would be doablea couple times per day, if necessary...


All these little dots... are spaces where my brain is working too hard to put words together at the same time, so I'm thinking in visuals

thomas rubino wrote:Hey Carla;
You're thinking outside the box again... always a good idea.

Muuahahaha! You, sir, have no idea, lol!!

thomas rubino wrote:Perhaps instead of a Rocket burner, a homemade incinerator with a weed burner?  

I'm not quite sure I get what you mean, there? My dad built a few incinerators, in his time, though he was definitely not a pro, and things didn't always line up quite right... But, the weed burner... you mean the little mini flame throwers for killing weeds? I'm struggling to wrap my overtired brain around this, yet it seems like it should be pretty simple. Maybe it's time to sleep on it. It's almost 2:30am, and I'm struggling to think of anything but my pillow, after my last post... so that's likely why there's only a single brain cell or two working on it. But, this whole thing is stuck in my head, now. There has to be a way...

Hi Carla, a nice thought experiment. But I think the downsides are immense. Specifically the necessary handling and drying of the material prior to incineration.
What are the arguments again using a Jenkins style dry toilet with hot composting using a couple of buckets? That way you can always have an empty bucket in the middle of the night or when you’re sick. With minimal interaction and a great end product.

I’ve used a simple two bucket urine diverting toilet. Essentially, a hole is dug in the ground to fit two buckets that touch each other. Two stones are placed one on either side for steps. Then you adjust it so that when you squat the poo goes in one bucket and the pee goes in the other. It shouldn’t be too hard to keep clean and doesn’t require any complexity in regards to how urine diverting toilets normally work. A sitting version might be possible too but may require more thought. I’m not using such a system now, but you’ve got to be on top of emptying the urine bucket frequently… after that a quick rinse will be beneficial.

Squatting isn't an option, for many - particularly for the aging &/or disabled. While we're all "aging", I don't consider myself to be "elderly", yet - but it's coming. And, I am disabled, so this really does need to be as hands-off as possible. I guess it's a good thing that at this point, it's really more a mental exercise, than anything. But, I'm not abandoning the idea, just yet.

Oh, and, um... something else to consider, in the separation of liquids & solid plan - as we age, that urine flow changes. It's involuntary. Direction becomes increasingly less sure, and consistency of stream disappears - for both men and women. So, any form of toilet we choose needs to be able to take that into consideration, too - especially if we intend it to be the last one we install, which would be the case, for me. Absolutely no steps, no squatting, and minimal handling.

At first blush, I think I'm leaning toward the dehydrate first (and possibly later char/combust) approach for a mobile installation.

I have no direct experience.  But, I did look into the incinerator toilets when my son was contemplating building out a van (in his case, the RAM [i.e. Dodge] version of a Mercedes high roof) - requests for technical support from him are common.  He works as a medical traveler, at the moment, and is pretty adventurous in his off time (mountain biking, hiking, somewhat technical mountaineering [Hood, Ranier, Shuksan, 14ers]) so a mobile base of operations could kill two or three birds with one stone - portable principal residence, adventure base camp, and eventual temporary quarters while he builds a fixed home place.  But, he decided not to go that way, at least for now, though it remains as a future option.

Anyway, the commercial incinerator toilets are, as Carla noted, decidedly un-cheap (even used), so this lateral thinking is, in my estimation, a worthwhile endeavor.  Add to this that a secondary fuel system might need to be managed (diesel, propane, maybe compressed natural gas), and the luster fades, somewhat.  Managing a bit of fire wood, especially rocket grade fire wood (i.e. twigs and branches) is simpler.

One advantage of the drying first approach is that it gives some flexibility as to when the final "treatment" occurs, if at all.  It may not always be convenient or necessary to fire up the rocket stove in warmer weather.  But, warmer weather might correlate nicely with solar gain much of the time, meaning the solar dehydrator idea would be possible.  The desiccated intermediate "product" could also be composted, if the opportunity presented itself, bypassing the final phase.

Carla's notes about the practicalities as bodies age are duly noted.

Considerable design/engineering may be needed to make such a system workable.  For inspiration, I spent most of yesterday on a scaffold with the outlet from the power vent of our composting toilet blowing near me, sometimes directly in my face (this is at our lake lot, so occasional recreational use); it could have been worse, but even though this seems to be composting pretty well at the moment, it was still a bit "fragrant" due to recent use.  Ruminating...

On edit:  It comes to mind that the prime mover of a van is probably only 1/3 thermally efficient, meaning that 2/3 (or even as much as 3/4, depending on whether diesel or gasoline, and the exact vintage of technology) of the available energy in the fuel is "waste" heat.  I wonder if an exhaust manifold "stove", similar to the old-fashioned carburetor intake air preheaters or the Model T manifold ovens, could be rigged up to provide "process heat" for the dryer?  Still with a solar dryer for when parked, though.  Still noodling on this...