112 Organic waste recycling: technology and management
Figure 3.7 The Clivus Multrum (Rybczyski et al. 1978; reproduced by permission of the
International Development Research Centre, Canada)
Anaerobic composting
Pit latrines (or holes in the ground) are the simplest form of anaerobic
composting toilets. The excreta deposited into the pit is decomposed
anaerobically. When the pit is about two-thirds full, it is filled up with dirt and
left there for approximately 2-3 years. After this period, the excreta would be
well stabilized and the pathogens inactivated, rendering it for satisfactory use as
soil conditioner. To avoid the occurrence of obnoxious odor, ventilated
improved pit (VIP) latrines were developed (Figure 3.9) which have yielded
encouraging results in many places such as Zimbabwe (Morgan and Mara 1982)
and Botswana (Nostrand and Wilson 1983).