Ecosan Systems - Highland 1 2 3 4
1. The double-vault dehydrating toilet (Mexico)
Double-vault dry toilets have been used in northern Vietnam for a long time. The toilet consists of two processing chambers covered with a squatting slab that has two drop holes, footrests and a groove for urine. At the back there are two openings for the removal of the dehydrated material.
People excrete in one of the chambers. Before the vault is used for the first time, the floor is covered with a layer of powdered earth. The purpose of this earth is to absorb moisture from the faeces and to prevent them from sticking to the floor. After each use people sprinkle two bowls of ashes over the faeces. The ashes absorb moisture, neutralize bad odours and make the faeces less attractive to flies.
Urine drains away through the groove in the slab and collects in a jar behind the toilet. Paper used for anal cleaning is dropped in a box or jar and burnt. Thus in the receptacle there are only faeces, ashes and soil. The urine is used as a fertilizer (Use of products).
When the first vault is two-thirds full, the person in charge fills the vault to the brim with dried, powdered earth, and seals the vault. The other vault now comes into use instead. When the second vault is nearly full, he or she opens and empties the first vault. The dehydrated faeces are used as fertilizer. In highlands where temperature may be cool, a storage time of 1.5 year is recommended, followed by sun drying. However, the use of a solar heater shortens the storage period (see example on page 3).
