Composting Toilet System
Added to website: 29 June 2006
The composting toilet system is ideal for use by the Pacific Island community. It requires no water and produces valuable fertiliser from human waste. In addition it does not produce the foul smells and harmful pollution often associated with other types of toilets.
The toilet described in this booklet was built in 2006 on the island of Dravuni in the Fiji Islands by members of Coral Cay Conservation along with people from the village of Dravuni.
Workings
Human waste decomposes readily in the presence of air to produce a clean manure. It is essential to remove excess liquid to ensure air can circulate, and to prevent bad smells developing. This is achieved by allowing the waste to fall into a bin with a filter in the bottom. Below the filter a plastic tube leads out into a small wetland; the filter helps to ensure the tube does not block. The wetland is lined to prevent pollution, and planted with things like sledge and kuta which absorb water.
Filter preparation and use
The wheelie bin requires a wire mesh suspended several inches from the bottom of the bin. We rested it on the ‘shelf’ at the base of the bin, and supported it using a cut piece of large-diameter pipe. Above this is a thin layer of coconut husk which prevents solid waste passing through the mesh. On top of this should be placed a layer of completed compost from a previous bin, or if unavailable a layer of good quality soil – about 2-3 inches. Lastly some dried leaves or grass should be added to support the decomposition.
A handful of dry leaves or grass should be added every day when the toilet is in use to assist the composting process.
Ventilation
The vault containing the bin should be ventilated with a pipe at least 6 inches in diameter. This should be painted black above the roof to allow heat to assist the ventilation. A T-piece (also black) placed on top pointing with the prevailing wind will also improve ventilation.
The vault itself should be otherwise sealed to prevent flies entering, and to prevent odours. This can be achieved using bicycle tyre inner tube on the door frame against plastic on the door itself.
Plumbing
The pipe leading from the base of the bin to the wetland should be well sealed to prevent leakage; it is best to test it before use. Inside the wetland, the pipe should be drilled along its length to allow the liquid to escape. A layer of small stones surrounding the pipe will help to prevent blockages.
Composting
When the bin is full it should be removed from the vault, closed, and left in a dry well ventilated location for two to three months. Other bins must be rotated into the vault during this time. The compost should be dark, crumbly with a slightly sweet or musty smell when it is ready for spreading.
For more information including construction and photographs click here
