Akvouser
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The Fossa Alterna is a shallow alternating double pit system, collecting and compos ting excreta from a dry toilet. Two shallow pits are dug next to each other (0.5 1.5 metre deep). Dry leaves are added to the pit base before use, and thereafter soil (and ash) are added after each defecation. When a pit is 3/4 full, the concrete slab and portable superstructure are placed on the second pit. Excreta is not only collected, but also (pre-) treated by filling the original pit with soil and leaving it to compost. By the time the second pit is full, the first pit is emptied after which the slab and superstructure is put back on top of it and the pit is reused. After composting, the content of the first pit can be used as fertiliser. The best compost time is more than 12 months. The material can be excavated earlier at 6 months, but is best transferred at this stage to a pit in which a tree will be planted.
*Small / medium sized - Capacity: about 0.5-0.75 m3 - Filling time: 6-12 months