Ecological Sanitation: A Concept
Practical Action
Critically, ecosan (if operated correctly) achieves the primary goal of minimising disease via
treating faeces (or combined faeces and urine) and separating waste from householders whilst
it contains dangerous pathogens. Crucially it also prevents these pathogens from entering the
water cycle.
Types of Ecological Sanitation
The types of ecosan toilet can be separated into two categories, dehydrating and composting.
Within these categories there is also a distinction between urine diversion (those that separate
urine from faeces to achieve a variety of benefits) and systems which mix both urine and
faeces. There are a variety of models operating in slightly different ways.
Types of treatment are split into primary and secondary treatment. Primary treatment occurs
in the ecosan facility itself (on-site) through such processes as increasing pH level or reducing
the moisture content. Secondary treatment takes place by transporting the waste to an
alternative location (off-site) for further treatment such as composting or incineration. Many
household facilities perform secondary treatment by leaving the waste in storage and not
adding further faeces i.e. an alternating pit system. If human waste is collected and mixed
together to be used on a large scale further secondary treatment should take place to ensure
it is pathogen free (some users may not take as much care managing their own facilities, to
ensure safe pathogen levels secondary treatment is highly advisable). For further details refer
to the technical brief ‘Re-use of excreta and urine from ecological sanitation’.
Specific details about a form of composting toilet are given in the Practical Action technical
brief ‘Compost toilets and eco sanitation toilets’. It is important to acknowledge that these
toilets are part of ecological sanitation and to understand the overall concept. This section
will briefly describe the characteristics of each toilet category and give some brief examples.
Dehydration Toilets
Dehydration toilets reduce the pathogen content in human excreta through a series of
processes. The moisture content is reduced (therefore these types of facility always use urine
diversion) and ash and lime are added after each use to increase the pH (above 9.5). The
dryness and high pH, combined with the time left in storage, eventually causes the die off of
all pathogens. The dryness of these facilities also means there is less of an environment for
flies to breed, creating a more pleasant environment for the user.
In areas where water is used for anal cleansing
there is a risk of the contents of dehydrating toilets
becoming too wet and therefore not operating
properly. The Kerala double vault toilet (figure 3)
contains a trough over which to wash to prevent the
contamination of the drying waste. In this system
the water is collected together with the urine.
Figure 3: Kerala double vault dehydration toilet [Illustrator: Hans Mårtensson; Source: Winblad and
Simpson-Hébert, 2004]
3