Composting Toilet

This is the exact technique for a simple composting toilet that we use at Factor e Farm (from a Humanure Handbook, (see exact page and further pictures):

“How it works is a model of simplicity. One begins by depositing one’s organic refuse (feces and urine) into a plastic bucket, clay urn, or other non-corrodible waterproof receptacle with about a five gallon (20 liter) capacity. Food scraps may be collected in a separate receptacle, but can also be deposited into the toilet receptacle. A five gallon capacity is recommended because a larger size would be too heavy to carry when full. If five gallons is still too heavy for someone to carry, it can be emptied when half-full.

The contents of the toilet are kept covered with a clean, plant-based cover material such as rotted sawdust, peat moss, leaf mould, rice hulls, or grass clippings, in order to prevent odors, absorb urine, and eliminate any fly nuisance. Urine is deposited into the same receptacle, and as the liquid surface rises, more cover material is added so that a clean layer of organic material covers the toilet contents at all times.

A lid is kept on the toilet receptacle when not in use. The lid need not be air-tight, and a standard, hinged toilet seat is quite suitable. The lid does not necessarily prevent odor from escaping, and it does not necessarily prevent flies from gaining access to the toilet contents. Instead, the cover material does. The cover material acts as an organic lid or a “biofilter”; the physical lid (toilet seat) is used primarily for convenience and aesthetics.”

The idea of a composting toilet is to keep compost around 43-50°C (110-122°F) for at least a week, to create an environment in which beneficial microorganisms thrive and pathogenic ones die. The Humanure Handbook says, "A sound approach to pathogen destruction when composting humanure is to thermophilically compost the toilet material, then allow the compost to sit, undisturbed, for a lengthy period of time after the thermophilic heating stage has ended."

The way to accomplish this is -
 * Use sawdust to bury manure. Sawdust provides carbon and this balances the nitrogen in the faeces. A good carbon-nitrogen balance is needed for composting. The sawdust also keeps bad smells in and keeps flies away. Biochar could also profitably be used for this purpose.
 * Do not seperate urine and feces, as the urine provides moisture the microorganisms need.
 * As well as adding the buckets from the toilet to the compost heap, throw on chunky materials like straw. This traps air pockets in the compost heap.
 * Optionally, skewer the compost heap with sticks or pipes to provide more aeration.
 * Let it sit for a year before using on plants

You can read The Humanure Handbook, 3rd edition here