Literally! Am half way through this fascinating ebook. All about recycling poo! He makes a convincing case for them, but they aren't yet possible for me to set up at home.
When the shit hits the fan and the global crisis reaches its nadir, we're going to have to first harvest our own drinking water then dispose of it safely. For that I'd check out the following:
Input: drinking water from rainwater
Output: pee and poo!