l116.
For ideas about the treatment of human waste in a closed-loop system see, for instance, Nick Grant, Mark Moodie and Chris Weedon (1996), Sewage Solutions: Answering the Call of Nature; Peter Harper and Louise Halestrap (1999), Lifting the Lid: An Ecological Approach to Toilet Systems; Patrick Whitefield (2004), The Earth Care Manual, chapter 5; and Lyla Mehta and Synne Movik (2010), Shit Matters, Practical Action Publishing.