The Nature’s head is *not* a composting toilet, or a finished toilet solution
No matter what their marketing material says. It is a crap-dehydrating, piss storing toilet. And it is not, in itself a solution to the sanitation problem.
In the humanure handbook, Joseph Jenkins explains that the composting process is very slow at room temperature. The Nature’s head only stores for 30 person-days, which is not long enough.
More importantly, don’t confuse pathogen destruction with composting. A toilet like the eco-let causes pathogen destruction just by letting the stuff age for several months. In the humanure handbook there is some info in how long you need to leave humanure in order to allow various pathogens dies off – E-coli dies pretty fast, but worm eggs, for instance, take 1 to two years. From the info provided, it is apparent that 30 days will not help much.
Secondly, it gets a lot worse. Think about it for a second – the *oldest* batch is 30 days old, but the latest pile of crap is a little as 0 days old at the time when you empty it. An eco-let has multiple chambers, so that the compost that gets out has all be aged long enough, not just some of it.
And it does nothing at all with the urine. What are you supposed to do with it? And the urine will stink if left standing – ever forgotten to flush the toilet overnight with urine in it (admit it)? That’s the effect of anaerobic degradation, with the organisms producing hydrogen sulfide and other unpleasant smelling substances, which are not produced by aerobic decomposition.
Secondly, even if there were not disease causing organisms present in the urine when it was deposited, some of those organism that prefer anaerobic conditions are themselves pathogenic, capable of causing pneumonia and other illnesses, and they are bound to start growing in there sooner or later, since they are fairly common in the environment (but not in quantities high enough to cause illness).
Now I’m sure it could be useful as part of a larger sanitation scheme. And don’t think I am trying to overstate the risk of contracting a disease – the probability that someone will contract a disease from the humanure involved is never any greater than the probability that someone using the toilet is infected with a disease that can be transmitted by the fecal route.
For a more complete, but still portable option, search this blog for “pasteurize dehydrating toilet”.
Here are some links to stuff I previously said about the possibility of a pasteurize dehydrate toilet.