An idea popped into my head recently and I don't know if it has ever been done.
Could you use a urine diverting toilet to collect solid human waste into a removable chamber that doubles as a biochar burn chamber? This would change a potentially dangerous waste product into a valuable soil amendment.
Good idea or does it suck?
Making biochar out of humanure would drive off most of the nitrogen, which is one of the main plant nutrients present in the manure, and a limiting nutrient for gardening and vegetation in general. Conventional composting would lead to much less N loss.
I think you'd be wasting the special properties of poop by burning it. I'm trying to think more in the direction of maximum utilization of human leavings rather than a more disposal mentality. Yes, it would sterilize the poo, but you'd presumably lose some of the fertilizing and certainly some of the soil/microbe feeding properties. There are other way to make it safe, or just put it where it won't be contacted by people until broken down, like burying it. I'm going to try out a trench system using biochar as deposits are made, to basically make an engineered soil. The outhouse will move along the trench. I"m thinking this could make use of complimentary attributes. Biochar, holds nutrients and improves aeration and absorbs odor, poo adds nutrients, charges char, encourages active microbial activity by giving them stuff to eat. http://turkeysong.wordpress.com/2014/07/29/soil-banking-with-biochar-latrine/ Not for everyone, but it's simple and seems like it would make good use of poo, while being safe enough and, especially with the addition of some other stuff, creating a soil that might continue to be awesome for centuries. For permanent sites, I am partial to the Ecosan urine diverting designs. Though I've never used one, it seems like a good system, easy to maintain and saves probably the great majority of the nutrients. I'm definitely all about urine diversion. It's special property of being full of soluble nutrients can be use to great advantage for fertilizing where and when you want. I think it's important to be cognizant of the possible health hazards of human feces, I'm inclined to think burning it is probably unnecessary and probably somewhat wasteful of it's potential.
John, I think that's brilliant. If without urine, with sawdust, then baked in an oven/ gasifier, even ebola would be dead. The nitrogen's mostly in the pee, so charing the #2 and sawdust wouldn't lose much N. Maybe a clay pot would be a good, heat-tolerant container. Perhaps a metal barrel would fit over the clay pot for the charring. Or it could go on a shelf inside the woodstove.
I've thought about this too in the event that the municipal sewer didn't work or the septic got full and there was no hope of it being evacuated.
Assuming that your primary goal is sanitation and not worried about nutrient loss it would be a great idea..
That is how we processed human excrement on deployments in the Military with two exceptions:
1. We used JP-8 Diesel fuel to burn it down to ash.
2. Wouldn't dare use it for anything.
My only personal consideration would be turning it into bio-char.. and not burying it on my suburban lot due to drainage/sanitary concerns.
It's material that you would just be flushing down the toilet anyway. Pun intended..
If I had land I would definitely look into composting it for a wood lot / orchard soil amendment.
I know it's been touched on, but using humanure to make biochar seems kind of like you're overdoing things. If you're already making humanure, why not just use it? Unless of course you're looking to skip the wait period and turn it into something useful, and thus not a hygiene hazard, quicker.
Personally I'd just stick with wood biochar. I can also imagine charring excrement would bring about a quite unpleasant smell lol
I've thought about this as a village scale system, or an amendment to current waste systems where solids can be filtered out, dried and treated through pyrolysis. There have been experiments in Japan which have shown pyrolysis of such solid mixed waste can greatly reduce toxicity through the biochar's ability to absorb heavy metals and other toxic substances commonly put down the drain. Separating it at the source, however, is certainly a valid idea.
This would make sense to try with solar drying toilets installed in the early earth ships, adding on a urine diverting system.
From my experience making Biochar, I wouldn't want the process anywhere near any flammable structure. Have you considered being able to remove the container from the toilet before ignition?
Drying human feces will take a lot of space and be a hygiene problem because of flies, and a smell problem. Then someone will have to collect it and put it in containers to be put into ovens to make biochar. Even dried human feces are not pleasant -- believe me, I've seen a lot because I've lived in India for over 20 years!
It seems to me a lot more hygienic, and better for soil, to simply cover feces as soon as they are produced and let them compost. No smell, no flies, and good soil amendment produced at the end.
Works at a residential alternative high school in the Himalayas SECMOL.org . "Back home" is Cape Cod, E Coast USA.
P Lyons wrote:There is work being done on this subect referred to as terra preta sanitation -
As far as I can tell, the terra preta sanitation concept doesn't convert feces to charcoal, but uses charcoal from other sources to absorb nutrients from mixed urine and feces. So it differs from the original idea of this thread.
The lactic acid bacteria method of reducing smell that is mentioned in the terra preta sanitation videos interests me. I wonder if lactic acid bacteria can reduce odor from stored urine from a urine diversion toilet.
Brian - You assessment of my post is correct, I guess I misread the original posts.
There is a relatively recent post Storing Source Separated Urine which discusses various options associated with preventing odour from source separated urine, and some good information of using lactic acid bacteria.