In composting toilet systems either a toilet with urine diversion or no urine diversion is used (see overview in figure 12). In case of no urine diversion toilet, faeces and urine with or without toilet paper depending on the user’s habit drop into the composter located just below the toilet. In urine diversion toilet, urine is collected separately and kept in a storage tank until it is ready for use in agriculture or just treated in a soak pit or evapotranspiration bed. However, leaching from soak pit can cause heavy groundwater pollution. Faecal materials are composted or dehydrated for a long time and reused as fertiliser and soil conditioner in agriculture.

In composting toilets, low temperature composting occurs because only a small amount of materials enters every day, which is not sufficient to prevent the heat loss from the heap (Gajurel, 1998). Moreover, aeration, which is a very importantfactor in the composting process, is poor inside the material of the composting toilet, even if material with high structural stability is added, because structural material cannot be mixed with faeces properly unless they are turned mechanically. As a result, aerobic micro-organisms cannot find proper Environment to work actively. Because of low temperatures in composting toilets, other methods such as a long retention time and ash as an additive among others are applied to kill pathogens.

Urine diversion is crucial for dehydration toilets. The non-diluted faecal materials (faeces and toilet paper if used) drop into the dehydrating vault located just below the toilet and are dehydrated with the help of heat (Solar radition), ventilation and the addition of dry materials.

Figure 12: Overview of toilet systems for source control sanitation (Otterpohl 1999 - www.gdrc.org/uem/waste/oldenburg.html)