eThekwini Municipality is one of the leading municipalities in South Africa with regard to the provision of basic sanitation services. The municipality have selected urine diversion toilets as the preferred delivery mechanism for certain communities in their area of responsibility. The first units were installed in 2003 and there are more than 33 000 urine diversion toilets in communities outside the urban centre, built according to a constantly improving design that was initially based on a number of guiding principles. It is planned to have 47 500 installed by 2007.
The eThekwini urine diversion toilets were installed because of the municipality’s experience in the logistical difficulties and excessive cost associated with the emptying of VIP toilets. The municipality realised that they did not have a complete knowledge of urine diversion toilets, hence their request for research support. The risks associated with different disposal routes for the solids from vault need to be evaluated.
The eThekwini UD toilets have a number of unique features which were developed to suit local conditions. The basic design is a double vault composting dry toilet with urine diverted to a soak-away located near the unit. A pedestal is located above one pit, into which faeces, anal cleansing material and bulking agent are dropped. Once the first vault is full, the pedestal is moved to the hole above the second vault and the first is sealed and allowed to stand. Once the second vault is full, the first vault is opened via a back plate and manually emptied by the householder or a contractor. The emptied contents are buried on the householders property and the burial site marked by planting a tree over it. The pedestal is then returned to its position above the first vault and the second vault is closed and left to stand while the first refills. It is expected that each vault will take between 6 months and one year to fill, resulting in a range of vault contents age of between 6 months and two years at the time at which they are removed from the vault.
The principle behind this design is twofold:
- Biologically-mediated stabilisation and drying of organic material will occur in the pit, rendering it less unpleasant to handle; and
- Sufficient pathogen deactivation will occur during the standing phase to reduce the risk of disease transmission during manual emptying of the pit
The motivation for a urine-diverting design is that the volume of material that requires handling is substantially less than in a pit latrine which receives urine and often grey water as well as faeces and cleansing material. Thus a far smaller vault needs to be constructed. The smaller volume of the vault contents and their relative dryness means that they can be removed relatively easily by the householder with an appropriately sized rake or spade.
Despite the obvious benefits of the design, there are a number of unresolved scientific, technological, social and health-related questions about how the design works from a biological and mass transfer perspective, and what the real health and environmental risks are to the householder, community and any outsiders involved in the pit emptying process. In particular the risk of infection by geohelminths such as Ascaris sp. has been identified as being an important factor in calculating the benefit of sanitation provision in terms of community health and quality of life. The infection cycle can be broken by a combination of hygiene education and practice, chemotherapy and improved sanitation. The fate of Ascaris Spp. eggs in the urine diversion toilet is an important issue. Extended anaerobic conditions will result in the ultimate death of the eggs, thus burying the contents of a urine diversion toilet may be effective in breaking the infection cycle.