Types of Composting Latrines

Composting latrines can be divided into two basic types, non urine-diverting and urine-diverting.

1. Non Urine-Diverting Latrines


The decomposition or biodegradation process in this type of latrine can occur through aerobic conditions or anaerobic conditions.


• Aerobic Composting

The first type is a single vault system. This type uses solar panels to heat the compost. An increase in temperature aids in the pathogen reduction through thermal-dependent aerobic bacteria. Sawdust and toilet paper are added to adjust the moisture content of the waste.
The second type is a double vault system which is similar to the single vault, but it has two chambers. This method allows for long-term composting.

• Anaerobic Composting

Anaerobic conditions are achieved through batch composting by eliminating the compost's exposure to oxygen.
This latrine is built as a double vault system. When one pit is filled up two-thirds of the way, it is topped with earth and anaerobic composting takes place while the second pit is in use. After the second pit is filled up, the first pit is emptied and the cycle begins again.
(Source:CEP Technical Report)


• Examples of Non Urine-Diverting Latrines:



• Fossa Alterna


The Fossa Alterna latrine consists of two permanent, partially lined shallow pits and a movable latrine slab. Fresh excreta are covered with ash and soil. After about a year of use, the first pit is covered and allowed to decompose for three to four months. Meanwhile, the second pit is used as explained above in the batch composting and the cycle is repeated.

For more information, check out the following links:
Research and surveys of people from Niassa, Mozambique with Fossa Alterna latrines
Advantages and Disadvantages of the Fossa Alterna


• ArborLoo


In this case, when the latrine is two thirds of the way full, the toilet is moved and the remaining pit is topped with composted soil, this becomes the hole for planting a tree. As the latrine is being used ash and soil should be added to reduce flies and odour. Kitchen waste can also be added to help decompose the material. This forms a nutrient-rich humus, perfect for planting a tree!

The young tree is then planted within the hole and watered and allowed to grow and mature. The most suitable trees for this are paw paw, guava, mango, avocado and mulberry. Orange, naartjie, “neem” and Moringa are also being examined. Because the latrine is linked with a tree it is called an “ArborLoo.”

Click on the following two links for great ArborLoo reference sites. These pages include pictures, diagrams, and instructions on construction.
ArborLoo Reference I
ArborLoo Reference II
2. Urine-Diverting Latrines


The composting in this type occurs through dehydration.
The first type is a single vault system that separates the urine and feces to decrease the moisture in the pit.The urine is diverted to a pit filled with gravel and sand. Lime is added to raise the pH above 10 to aid in pathogen reduction.

The second type is the double vault. It is similar to the single vault except there is a barrier between the waste that is dehydrating and the fresh excreta coming in.
(Source: EcoSan article on latrine types for hot, arid climates.)



• Example of Urine-Diverting Latrine:



• EnviroLoo


The EnviroLoo is a dehydrating latrine. Click here for a discription of the operational principles of this latrine.